1
Q
5 Morphologic characteristics of Staphylococcus aureus
A
Gram-positive cocci
Catalase+
Coagulase+
Beta-hemolytic
Mannitol fermenter (turns salt agar yellow)
2
Q
Main virulence factor associated with Staph aureus — component of cell wall which binds Fc region of Abs and prevents complement activation thus preventing opsonization and phagocytosis
A
Protein A
3
Q
What area of the body does Staph aureus tend to colonize?
A
Nares (nose)
4
Q
What are the 5 inflammatory diseases caused by Staph Aureus?
A
- Post-viral bacterial pneumonia (patchy infiltrate on CXR)
- Septic arthritis (#1 cause)
- Large erythematous abscesses
- Rapid onset bacterial endocarditis (IV drug use, often tricuspid valve)
- Osteomyelitis in adults (#1 cause)
5
Q
3 morphologic features of Staphylococcus epidermidis and saprophyticus
A
Gram+
Catalase+
Urease+
Coagulase -
6
Q
What morphologic feature differentiates Staphylococcus aureus from Staph epidermidis and saprophyticus?
A
Staph aureus is coagulase+
Epidermidis and saprophyticus are coagulase -
7
Q
What organism is a part of normal skin flora and tends to infect hardware, orthopedic joints, heart implants, catheters, etc.?
What virulence factor contributes to its ability to do this?
A
- Staphylococcus epidermidis
- Polysaccharide capsule: ability to form biofilms to stick to metal and plastic surfaces
8
Q
What organism is associated with contamination of blood cultures?
A
Staph epidermidis
9
Q
What is the major clinical manifestation of staphylococcus saprophyticus?
A
UTI’s in sexually active females (2nd most common cause to E.coli) “Honeymoon cystitis”
10
Q
Morphologic features of streptococcus pyogenes (group A strep)
A
Gram+ cocci in chains
Microaerophilic
Hyaluronic acid capsule
Beta-hemolytic
11
Q
5 Virulence factors associated with S. pyogenes (Group A strep)
A
M-protein (anti-phagocytic, humoral response - Abs to heart)
Streptococcal pyrogenic exotoxin
Streptolysin O
Streptokinase
DNA-ase
12
Q
Clinical manifestations of strep pyogenes infection (note which ones are toxin-mediated vs. M-protein mediated)
A
Pyogenic infections:
Impetigo, strep throat, erysipelas, cellulitis
Toxin-mediated:
Scarlet fever, TSLS, Necrotizing fasciitis
M protein-mediated:
Rheumatic fever = polyarthritis, endocarditis (mitral valve), nodules on extensor surfaces, erythema marginatum, sydenham’s chorea [JONES]
Post-streptococcal glomerulonephritis:
Facial edema, hematuria (“cola” colored urine), HTN
13
Q
How would you test for a group A strep infection?
A
ASO antibody titer
14
Q
3 symptoms of Scarlet fever?
Caused by what toxin?
A
- Strawberry tongue
- Pharyngitis
- Widespread rash that spares the face
- Caused by streptococcal pyrogenic exotoxin (SPE)
15
Q
Which superantigens mediate TSLS vs. Necrotizing fasciitis in strep pyogenes infections?
A
- TSLS = SpeA, SpeC
- Nec Fasc = SpeB
16
Q
Post-streptococcal glomerulonephritis tends to occur after what type of strep pyogenes infection(s)?
A
Either pharyngitis OR superficial infection like impetigo
17
Q
Rheumatic fever tends to occur after what type of strep pyogenes infection(s)?
A
Pharyngitis only (NOT impetigo!)
18
Q
What organism tends to cause serious infections in newborns, thus pregnant mothers should be swabbed at ~35 weeks?
A
Streptococcus agalactiae (group B strep)
19
Q
Morphologic features of strep agalactiae and distinguishing tests?
A
Gram+ cocci in chains
Facultative anaerobe
Beta-hemolytic
Polysaccharide capsule
cAMP test + (increasing zone of hemolysis when plated w/ S. aureus)
Hippurate test +
20
Q
Clinical manifestations of streptococcus agalactiae (Group B strep)
A
- Neonatal meningitis (no nuchal rigidity!) = #1 cause
- Strep throat (pharyngitis)
- Pneumonia
21
Q
Morphologic features of streptococcus pneumoniae?
A
Gram + diplococci
Polysaccharide capsule = major VF
Alpha-hemolytic
Facultative anaerobe
Optochin-sensitive
Bile-soluble
22
Q
Characteristic feature of otitis media caused by streptococcus pneumoniae
A
Bullous meringitis
23
Q
Major virulence factors of strep pneumoniae?
A
- Polysaccharide capsule
- IgA protease = allows colonization and invasion of mucosa!
24
Q
Diagnosis of strep pneumoniae involves the ____ reaction, which turns blue in the presence of strep pneumo
A
Quelling
25
Clinical manifestations of streptococcus pneumoniae?
#1 cause of what conditions?
#1 cause of MOPS:
- Meningitis
- Otitis media
- Pneumonia - often lower lobes, PMN-rich **rust-colored sputum**
- Sinusitis
26
Morphologic features of streptococcus viridans?
How to distinguish from Strep pneumoniae?
Gram+ cocci in chains
Facultative anaerobe
Alpha-hemolytic
**Optochin-resistant** (allows to distinguish from S. pneumonia)
**Bile-resistant** (allows to distinguish from S. pneumonia)
**No capsule!** (allows to distinguish from S. pneumonia)
27
Major virulence factor associated with streptococcus viridans?
Allows it to do what?
Extracellular **dextrans** —\> adheres to platelets, especially in damaged heart valves (i.e., most often **mitral valve**)
28
Clinical manifestations of streptococcus viridans?
- Dental caries (strep mutans)
- Subacute bacterial endocarditis (only affects previously damaged heart valve — usually **mitral valve**) - Strep Sanguineous
29
Morphologic features of S. bovis
Gram+ cocci in chains
Facultative anaerobe
Usually **gamma-hemolytic**
Grows on bile (Bile resistant)
30
Clinical manifestations of S. bovis
**Same as enterococcus:**
**-** Subacute bacterial endocarditis
- UTI
- Biliary tract infection
31
S. bovis has a strong affilitation with what type of neoplasm?
Colorectal neoplasms
32
Morphologic features of Enterococcus faecalis and faecium?
- G+ cocci in chains
- Facultative anaerobe
- Usually gamma-hemolytic
- Grows on bile and 6.5% NaCl
- **Hugely abx resistant (VRE), nosocomial infections**
33
Morphologic features of Bacillus anthracis?
Gram+ rods in chains **(unique!)**
Protein capsule **(poly-D-glutamate)**
**Aerobe** (but can grow w/o O2 so is **facultative anaerobe**)
Spore-former
34
Differentiate the 2 toxins associated with bacillus anthracis
**Lethal factor** — protease **exotoxin** that stimulates macrophage release of **TNF** and **IL-1B** contributing to **death**
**Edema factor** — acts on adenylate cyclase to **increase cAMP (intracellulary)** —\> massive edema (resists phagocytosis)
35
Complication of GI anthrax?
Necrosis of intestines --\> vomiting, abdominal pain and **bloody diarrhea**
36
Characteristic lesion associated with cutaneous B. anthracis infection?
Black eschar with surrounding (ring) erythema
37
Describe pulmonary anthrax
Known as what disease?
X-ray finding and progression?
- Caused by **spore** inhalation (wool sorter’s disease)
- Nonspecific symptoms at first, progresses to **mediastinal LNs ---\> MEDIASTINAL HEMORRHAGE**
**- Characteristic WIDENED mediastinum on CXR**,
38
Characteristics of bacillus cereus?
Often seen in what condition, caused by?
**Aerobic**
**Spore-forming**
Motile
**No** capsule!
**Food poisoning** from **reheating fried rice** — vomiting and diarrhea (heat labile vs. heat stable toxin)
39
Oxygen-status of all clostridium species
Obligate anaerobes: cannot survive around O2
40
Morphologic features of Clostridium tetani
Gram+
**Flagellated (H-Ag+)**
Spore-forming
41
Describe tetanus toxin associated with Clostridium tetani and its MOA?
- Tetanospasmin - released from vegetated spores at puncture site, travels **retograde,** goes from peripheral motor nerves to spinal cord.
- Acts as a **protease** on SNARE, inhibiting GABA and Glycine (inhibitory NTs) —\> muscle spasm (spastic paralysis)
42
Characteristic features of *C. tetani* infection
- Spastic paralysis leading to rigidity
- Rhesus sardonicus (lock jaw)
- Opisthotonus (exaggerated arching of back)
43
Morphologic fefatures of clostridium botulinum
Gram+
**Obligate anaerobe** (flourishes inside **canned foods**)
Flagellated (H-Ag)
Spore-former
44
Clinical features of *C. botulinum* infection in adults and infants?
Early sx's?
Adults: **DESCENDING** flaccid paralysis (**only affects PNS**), starts with diplopia, ptosis as initial symptoms
Infants: floppy baby syndrome
45
Pathogenesis of C.botulinum infection in adults vs. infants
**Adults**: ingestion of **preformed toxin** (once it has germinated in improperly canned food), toxin then **inhibits ACh** nerves — toxin is a **protease** that attacks SNARE protein
**Infants**: ingest **honey** that contains **SPORES**
46
Morphologic features of Clostridium difficile
Gram+
Spore former
Motile (H-Ag)
47
Describe the 2 exotoxins associated with *C.difficile* and what they cause.
**Exotoxin A** = binds brush border — inflammation, cell death, and **watery diarrhea**
**Exotoxin B** = disrupts cytokskeleton integrity, by depolymerizing actin — enterocyte destruction and necrosis —\> **yellowish grey exudate** called **pseudomembranous colitis**
48
How is *C. difficile* definitively diagnosed?
Look for **TOXIN** via **PCR assay of stoo**l
49
Morphologic features of *Clostridium perfringens*
Where is it found and associated with?
Gram+
Spore former
Non-motile! (found in dirt and soil - associated with combat wounds and motorcycle accidents)
50
Diseases associated with Clostridium perfringens and their pathogenesis
- **Gas gangrene (myonecrosis)** — **crackling sound on palpation** due to **alpha-toxin lecithinase (phospholipase)** that attacks PM leading to RBC hemolysis
- **Food poisoning** — **late-onset** watery diarrhea — ingest spores which then germinate in gut
51
Morphologic features of *Corynebacterium diphtheriae?*
Transmitted how?
- Gram+ rod, but **non-spore** forming
- **Club-shaped (VERY pleomorphic)**
**- Bacteriophage-derived toxin (MUST be lysogenized)**
- Facultative anaerobe
- Catalase+
- **Aerosol transmission**
52
Describe the *Corynebacterium diphtheriae* toxin MOA?
What must happen to the toxin for it to be active?
What are the clinical manifestations?
- Must first be **lysogenized** by a **temperate bacteriophage!**
- Acts by **ribosylation** — **inhibits EF-2** to inhibit protein synthesis —\> **gray pseudomembrane formation** over throat and tonsils
- Can cause airway **obstruction** and “**Bull’s neck” LAD**
- Other effects: **myocarditis (A-V conduction block and dysrhythmia)**, local paralysis (**starting in posterior oropharynx**) d/t myelin damage
53
Diagnosis of *C.diptheria* requires plating on what media?
How would you differentiate toxic vs. nontoxic strains?
- Swab membranes and plate on **Tellurite** and **Loeffler’s agar/media**
- Differentiate strains based on **Elek’s test**
54
Morphologic characteristics of *Listeria monocytogenes?*
Gram+ bacilli
**Beta-hemolytic**
Motile via flagella (**H-Ag**) — **“tumbling”** motility
**Catalase+**
**Facultative intracellular**
55
Risks for contracting *Listeria monocytogenes?*
Prefers what type of enviornment?
- Can survive in **cold** environments — contaminates refrigerated items like milk and soft cheeses
**- Pregnant women** at risk - may lead to **termination or disease in newborn,** can give baby meningitis (meningitis **also occurs in elderly** with this)
56
What major VF allows *L. monocytogenes* to escape the phagolysosome?
Listeriolysin O
57
What conditions are associated with *Moraxella catarrhalis* infection?
- **Otitis media** in pediatric patients (\<3 y/o)
- **COPD** exacerbations
- **URIs** in elderly
58
Morphologic features of Neisseria
- Gram-negative **diploccoci**
- Oxidase+
- Grows on **chocolate agar,** does NOT grow on blood agar
59
Since Neisseria cannot be grown on plain blood agar, what are the culture requirements for plating Neisseria?
Chocolate agar (heated blood agar)
VPN agar (Thayer Martin) = **selective agar**
60
Virulence factors associated with Neisseria?
**Pilli** — allow attachment to mucosa, antigenic variation
**IgA protease** — facilitates survival on mucosal surfaces Opa proteins
61
Which species of Neisseria is encapsulated (polysaccharide)?
How is it transmitted?
Where does it colonize first?
- Neisseria meningiditis
- Spread by respiratory droplets — first **colonizes nasopharynx**
62
Neisseria meningiditis ferments ____ and \_\_\_\_\_\_.
Most infections are caused by type _____ because it is not included in the vaccine.
\_\_\_\_\_ patients are at increased risk for this disease
- Glucose; **maltose** (only meningitidis ferments)
- Type **B**
- Asplenic and sickle cell
63
*Neisseria meningitidis* invades hematogenously leading to a massive immune response generated by what?
Leads to?,
- **LOS** proteins in envelope, which **bleb off** — causes inflammatory response --\> increased permability --\> leaky capillaries and hypovolemia
- **Petechial rash** indicative of thrombocytopenia (can lead to **DIC**) —\> eventual hypovolemic shock
64
What is Waterhouse-Fridrichson syndrome?
Occurs due to infection with?
Occurs with Neisseria meningiditis — characterized by hemorrhage/infarction of **adrenals**
65
Morphologic features of *Neisseria gonorrhoeae?*
Ferments what?
- Gram-negative cocci
- **Facultative intracellular (likes to infect PMNs)**
- Note that it is **NOT** encapsulated,
- **Only** ferments **glucose** (unlike N.meningiditis which is encapsulated and ferments glucose+maltose)
66
Clinical manifestations in *N.gonorrhoeae* in males vs. females?
Can spread to the perineum and form?
Manifestations in the infant?
**Males:** urethritis, white purulent discharge —\> **prostatitis, orchitis**
**Females:** can cause **PID** —\> **purulent white THICK discharge,** scarring, infertility, ectopic pregnancy,
**Fitz-Hugh Curtis** syndrome (**violin string adhesions on liver**) = PID spread to peritoneum
**Both** may exhibit polyarthritis (knees, often **ASYMMETRIC**)
Note that it can also be passed to baby during delivery causing **early onset conjunctivitis (5-7 days after birth)**
67
Fast vs. slow lactose fermenters?
**Fast:** Klebsiella, E.coli, Enterobacter
**Slow:** Citrobacter, Serratia
68
What 3 bacteria are urease+?
1) Klebsiella pneumoniae
2) Proteus mirabilis
3) Helicobacter pylori
69
Which 2 bacteria exhibit the following diarrheal manifestation:
Lack of cell wall invasion — entertoxin release leads to watery diarrhea
- ETEC
- Vibrio cholerae
70
Which 3 bacteria exhibit the following diarrheal manifestation:
Invasion of intestinal epithelium — adhere, invade, toxin release —\> system response results in local WBC infiltraton (leukocytes in stool), fever, and cell death causing blood diarrhea
Enteroinvasive *E. coli (EIEC)*
*Shigella*
S*almonella* enteriditis
71
Which 3 bacteria exhibit the following diarrheal manifestation:
Invasion of lymph nodes and bloodstream — WBC, RBC, abdominal pain; systemic response can lead to sepsis and bacteremia
1) S. typhi
2) Y. enterocolitica
3) C. jejuni
72
Describe characteristics of *Enterobacter cloacae?*
Ferments what?
Causes what infections?
Part of normal flora - cause **pneumonia, UTI** (multi-drug resistant nosocomial infections)
Ferments **lactose** (forms pink cultures on MacConkey agar)
Motile
73
Describe characteristics of *Serratia marcescens* infection?
Morphologic and lab characterisitcs?
- Often infects wounds, causes pneumonia, UTIs (multi-drug resistant nosocomial infections)
- Catalase positive
- Very motile
- Red pigment on culture
74
*Klebsiella pneumoniae* is an enteric with the potential to cause pneumonia, UTI, etc. and like other enterics, ferments lactose. What are the other morphologic features of Klebsiella?
Polysaccharide capsule (O-Ag)
## Footnote
**Immotile (unique!)**
**Urease+**
75
Characteristic findings for someone with a Klebsiella pneumonia?
What is seen on CXR?
- Bulging fissure on CXR
- **Currant jelly-thick sputum**
- Cavitary lesions — may originally suspect Tb
76
Morphologic features of *Salmonella typhi and enteritidis?*
Grows on what agar and appears how?
Gram-negative bacilli - **non-lactose fermenter**
**Motile** (H-Ag) and **Capsule** (Vi Ag)
Produces **H2S** —\> black colonies on **Hektoen agar**
**Acid labile - easily degraded by stomach**
Faculatative intracellular (in macrophages)
77
Where would you find *S. typhi* in chronic carriers?
Gallbladder
78
Clinical features of *Salmonella typhi* infection?
#1 cause of what?
- Rose-colored macules on abdomen
- Osteomyelitis in pts with sickle cell (#1 cause)
- Pea soup-diarrhea
79
Morphologic features of Salmonella enteriditis?
Has what to increase infectivity?
Gram-negative bacilli and **non-lactose fermenter**
Motile
Produces **H2S** —\> black colonies on Hektoen agar
Encapsulated (**Vi antigen**)
Acid-labile
Facultative intracellular (within macrophages)
Type III secretion system to **increase infectivity**
80
Clinical features of Salmonella enteriditis?
Acquire infection how?
- Acquired by eating **undercooked chicken**
- Causes **inflammatory diarrhea**
81
How would you differentiate Shigella from Salmonella infection in terms of plating?
**- Green colonies** on Hektoen agar INDOLE POSITIVE (Salmonella colonies are black)
82
Morphologic features of Shigella?
Transmission?
Which cells take this organism up once inside intestine?
- Gram-negative bacilli, unencapsulated, **Acid stable**
- **NON-**motile
- **NO lactose fermentation** and **NO H2S production**
- **Fecal-oral transmission**
- Taken up by **M cells**
- Type III secretion system
83
MOA of shiga toxin?
Inhibits **60s portion** of ribosomes — inhibits protein synthesis and killing intestinal epithelial cells (bloody diarrhea)
84
Clinical manifestations of *Shigella* infection
- Causes **bloody diarrhea** (inflammatory containing RBCs and WBCs)
- Damages endothelial cells within **glomerulus,** which activates platelets and causes **aggregation --\> thrombocytopenia**
- Shiga toxin may cause **hemolytic uremic syndrome** **(HUS)** in young patients (most common **under 10 y/o**) —\> **glomerular damage**, **thrombocytopenia**
85
Morphologic characteristics of *E.coli?*
Seen how on EMB agar?
Gram-negative bacilli
Catalase+
Facultative anaerobic
**Lactose fermenter** (pink MacConkey agar)
Siderophore
**Indole+ (Green on EMB agar)**
Encapsulated (**K-Ag**) and Flagella (**H-Ag**)
86
Which type of E.coli infection is often derived from undercooked meat and causes bloody diarrhea, and is also the only E.coli that does not ferment sorbitol?
EHEC
87
Describe the toxin associated with EHEC?
What strain is associated with outbreaks?
- **Shiga-like toxin** — causes **hemolytic uremic syndrome** (**HUS**) and **hemorrhagic colitis**
- **O157:H7** Ag associated with outbreaks
88
Describe the illness and toxin associated with ETEC?
Caused by what toxins?
- **Traveler’s diarrhea** from drinking contaminated water - causes **watery diarrhea**
- Heat **labile** —\> increased cAMP (similar to cholera toxin)
- Heat **stable** —\> increased cGMP
89
Characteristics of *Yersinia enterocolitica* infection?
Whom does it commonly affect?
Found where and transmitted via?
Morphological characteristics?
- Found in **puppy feces and milk products** — commonly affects toddlers leading to bloody diarrhea, fever, leukocytosis
- Resistant to cold temps (similar to *Listeria*)
- Gram negative bacilli
- **Bipolar (safety pin) staining**
- Encapsulated
90
Which bacterial infection can mimic an appendicitis?
- *Salmonella typhi*
- *Yersinia enterocolitica*
91
Characteristics of *Yersinia pestis;* causes what?
Reservoir and vector?
How does it inhibit phagocytosis?
- Reservoir = rodents and vector = fleas
- Bubonic plague —\> **buboes (LAD)**
- Endotoxin—\> necrosis of tissues and abscesses of organs
- Yersinia outer proteins (YOPs) secreted via type III secretion system, **inhibit** phagocytosis
92
Characteristics of *Campylobacter jejuni*?
Main reservoir?
Transmission?
- **Thermophilic (prefers warm temps)**
- **Curved** gram-negative rod
- Oxidase+
- Main reservoir = intestinal tract of animals (poultry)
- Fecal-oral transmission; contaminated water or ingestion of raw milk
93
Clinical manifestations of *Campylobacter jejuni?*
Post-infection complication?
- Bloody diarrhea, bacteremia d/t invasiveness, reactive arthritis (**Reiter’s syndrome**)
- Post-complication = Guillain Barre —\> ascending paralysis
94
Characteristics of *Bacteroides fragilis*
Gram-negative bacillus
Anaerobic
Normal flora of GI tract
NO lipid A!
95
Clinical manifestations of Bacteroides fragilis?
May complicate what?
- **Secondary infection** following abdominal trauma and/or localized abscesses
- May complicate abortion, tubo-ovarian abscess, IUD
96
Clinical manifestations of Bacteroides melaninogenicus and fusobacterium?
- **Melaninogenicus** - can cause a necrotizing anaerobic pneumonia, following- GI aspiration; may also exhibit pneumonic and periodontal manifestations
- **Fusobacterium** may have similar disease manifestations and rarely the etiology of otitis media
97
Characteristics of vibrio cholerae, parahemolyticus, and vulnificus?
Endemic where?
Grows on what medium?
- Gram-negative bacillus
- Endemic to developing countries (SE Asia)
- **“Comma” shaped**, grows on alkaline medium (**acid labile**)
- Oxidase+
98
Transmission and clinical manifestations of *V**ibrio cholerae?*
- Fecal-oral transmission via contaminated food/water
- Causes **profuse** watery diarrhea (**"rice water"** stool)
99
Main virulence factor and pathogenesis of *V**ibrio cholerae?*
- Fimbriae attach to intestinal wall and cholera toxin is released —\> **increased cAMP** —\> secretion of **water and Cl-** into lumen [other virulence factors: mucinase, motile via H-Ag]
100
What 2 bacteria are at high risk of transmission via contaminated seafood, typically oysters?
Which causes Acute gastroenteritis?
Which causes fulminating septicemia leading to death?
- *Vibrio parahemolyticus* --\> **fulminating septicemia** --\> Death
- *Vibrio vulnificus* --\> **Acute Gastroenteritis**
101
Morphologic characteristics of Helicobacter pylori?
Major virulence factor?
Strains expressing which toxin allows them to better colonize the gastric body?
- Curved Gram-negative bacilli
- Motile (allows them to move through **viscous** mucus)
- Oxidase+
- Urease+ = **major VF** (important for reducing acidity of environment)
- **CagA** expressing strains can effectively colonize the gastric body and cause **multifocal atrophic gastritis**
102
Clinical manifestations of H.pylori?
Increased risk for what cancers?
How is it transmitted?
What part of the stomach are they most often found?
- Duodenal ulcers (causes **95%** of duodenal ulcers)
- Fecal-oral transmission
- Increased risk of gastric adenocarcinoma, MALTomas
- Most often found in the **antrum**
103
Morphologic characteristics of *Pseudomonas aeruginosa?*
Produces what pigment?
Distinguishable odor?
- Gram-negative rod, **obligate aerobe**
- Oxidase+
- Catalase+
- Encapsulated
- Produces **pyocyanin and pyoverdin** —\> blue/green pigment
- Fruity **grape odor**
104
What distinguishes psuedomonas aeruginosa from other enterics?
Thrives in what enviornments?
- It is an **obligate aerobe** while most others are facultative anaerobes
- Thrives in **acquatic enviornments**, hot tub folliculitis
105
Clinical manifestations of *P**seudomonas aeruginosa?*
#1 cause of?
Affects patients with CF, IV drug users, and diabetics how?
(Hint: mnemonic BE PSEUDO)
- Complication of **B**urns
- **E**ndocarditis (frequently **right herat valve** in **IV drug abusers**)
- **P**neumonia (#1 cause of **gram-negative** nosocomial pneuomina; **CF** pt's and **immunocompromised**)
- **S**epsis (infected catheters)
- **E**xternal malignant otitis media
- **U**TIs (nosocomial)
- **D**iabetic **O**steomyselitis (IV drug users and children develop seconary to puncture wounds of foot)
106
What is the pseudomonas toxin?
MOA?
What is it similar to?
**- Exotoxin A** is **similar** to **Diphtheria toxin**
- **I****nactivates EF-2 by ribosylation**; leads to**inhibition of protein synthesis**
107
Characteristics of *P**roteus mirabilis?*
Characteristic odor?
May cause what type of infection?
- Gram-negative rod
- **Urease+**
- H2S+
- Facultative anaerobe
- **Swarming motility**, may have **fishy odor**
- Staghorn calculi
- May cause **UTI**
108
Proteus mirabilis cross-reacts with what other bacterial species?
Rickettsia
109
Characteristics of *Bordetella pertussis?*
How does it cause infection?
- Gram-negative rod
- **Filamentous hemagglutinin** pilus attaches to **ciliated epithelial cells** of the **bronchi** and releases toxins
110
Pathogenesis of *Bordetella pertussis* toxins?
- **Pertussis toxin:** Ribosylates Gi (disabling it) —\> increased cAMP
- **Adenylate Cyclase toxin:** Increases cAMP [same MOA as edema factor]
- Increased cAMP **disables chemokine receptor** for lymphocytes, leading to **Lymphocytosis** (increased WBC)
**- Tracheal toxin:** Damages **ciliated cell** in respiratory epithelium
111
Clinical findings associated with *Bordetella pertussis?*
Describe each stage/phase.
During which stage is the disease most contagious?
1) **Catarrhal stage**: lasts from **1-2 wks** of nonspecific findings including low-grade fever, conjunctival injection (red eyes), lacrimation, and mild cough
- Disease is **most contagious** during this stage
2) **Paroxysmal stage:** fever subsides and pt's develop the **characteristic cough -** intense bouts of nonprodutive forceful cough, can last **2 weeks - 2 months**
3) **Convalescent phase:** attacks becomes less frequent w/ a gradual reduction in symptoms; can last **up to 3 months**
112
Characteristics of *Haemophilus influenzae?*
What is special about the medium needed to plate it?
VFs?
Transmission?
- Gram-negative rod (**coccobacilliary shape**)
- Grown on **chocolate agar** with **factor V (NAD+)** and **X**
- VFs = Pilli, IgA protease, capsule (6 types)
- Aerosol transmission
113
Clinical manifestations of encapsulated *Haemophilus influenzae*
- Epiglottitis: inspiratory stridor, drooling, “**cherry-red epiglottis**”
- Otitis media
- Meningitis (**type B capsule only - most virulent**)
- Sepsis (**most common** in asplenic or sickle cell patients)
- Septic arthritis in **infants**
114
Clinical manifestations of nonencapsulated *Haemophilus influenzae*
Lack of invasiveness, so just causes **COPD exacerbations**, **otitis media**, and **sinusitis**
115
Clinical manifestations of Haemophilus ducreyi
Transmitted how?
**Chancroid (STI)** — painful genital ulcer rapid, **unilateral** painful inguinal LAD
116
Morphologic characteristics of *Legionella pneumophilia?*
How to visualize?
Needs what to grow on plate?
How is it transmitted?
- Gram-negative rod, but needs **silver stain** to be visualized
- Oxidase+
- Charcoal yeast with **cysteine and iron** for plating
- Facultative intracellular (inside **amoebas**)
- Aerosolized contaminated water is **inhaled** (i.e., air conditioners, produce mist machines, and shower heads)
117
How are infections with *Legionella pneumophilia* diagnosed?
Rapid **urine** Ag test
118
Clinical manifestations of the 2 types of infections with Legionella pneumophilia
**1) Legionnaire’s disease** — more common in smokers; atypical pneumonia with unilobar patchy infiltrate, hyponatremia, headache, confusion, diarrhea, high fever (\>104 F)
**2) Pontiac fever** — headache, myalgias, and malaise, followed by fever and chills - more self-limited
119
Morphologic characteristics of *Bartonella henselae?*
How to visualize?
- Gram-negative rod (zoonotic)
- Warthin starry silver stain
120
What diseases are caused by *Bartonella henselae* and what are their clinical features?
**Cat-scratch disease**: fever, painful regional LNs - **axillary lymphadenitis**, occurs in immunocompetent
**Bacillary angiomatosis:** also transmitted by cat scratches, occurs in immunocompromised **(HIV)** — fever, chills, HA, raised red vesicular lesions (similar to Kaposi sarc)
121
Characteristics of *Brucella?*
Found where and trasnmitted how?
- Gram-negative rod (zoonotic)
- Found in farm animals
- Direct contact w/ infected animal meat or ingestion of infected dairy products
- Facultative intracellular in macrophages
122
Clinical features of *Brucella* infection?
Characteristic of this infection?
**- UNDULATING fever** (characteristic), chills, anorexia, backache, and headache
- Since it colonizes macrophages, it causes **hepatosplenomegaly** and LAD
123
Characteristics of *Francisella tularensis?*
Vector and rervoir?
Why is this bacteria so dangerous?
- Gram-negative rod (**coccobacilli**)
- Encapsulated (**antiphagocytic)**
- Facultative intracellular in macrophages
- Vectors: ticks and deerfly
- Reservoirs: rabbits, squirrels
- POTENTIAL BIOTERRORISM AGENT — one of the most infectious pathogenic agents
124
Clinical features of infection with *Francisella tularensis?*
Can have a presentation similar to what other disease?
**- Ulceroglandular tularemia** — Painful ulcer with black base (center with caseating necrosis), fever, LAD, systemic symptoms
- Symptoms almost identical to **bubonic plague**
**- Pneumonia tularemia** — high mortality rate; via inhalation or through blood. Severe atypical pneumonia
125
Morphologic features of *Pastuerella multicoda?*
Where is it found normally?
- Gram-negative rod
- **NOT facultative intracellular:** part of normal oral mucosa flora of domestic (i.e., cats/dogs) and wild animals
- Catalase+
- Oxidase+
- Sheep’s blood agar
- Encapsulated -
- Bipolar staining (safety pin) - like yersinia
126
Clinical features of *Pasteruella multicoda* infection?
How is it most commonly transmitted?
- **Cellulitis** within 24 hours of bite; may progress to osteomyelitis
- Most frequent wound infection following a **cat** or **dog bite**
127
What differentiates *Pasteurella multicoda* from other zoonotics?
It is **NOT** facultative intracellular
128
Morphologic features of *Mycobacterium tuberculosis?*
Transmitted how?
- Acid-fast (mycolic acid in cell wall) - stains **red**
- Carbol fuscin stain
- Slow growing on Loenstein-Jensen medium
- Obligate aerobe
- Facultative intracellular (macrophages)
- Transmission via **inhalation**
129
Virulence factors of *Mycobacterium tuberculosis?*
- Cell wall has **glycolipids** allows for **clumping** of bacteria into **serpentine formation** called **cord factor.**
- **Cord factor** protects from destruction by eliciting **caseating granulomas (tubercles)** by increasing **TNF** and other **cytokines,** which activate **macrophages**
- **Sulfatides** prevent phagolysosome fusion
130
Clinical features of *Mycobacterium tuberculosis* primary infection?
What are the 3 outcomes of primary infection?
- Healed **primary infection** affects lungs (usually lower or middle lobe), lesions become **fibrotic** and eventually **calcify** as do **draining LNs,** together forms Ghon complex = **hilar lymphadenopathy + peripheral granulomatous lesion** in **middle** or **lower lung lobe**
**_3 outcomes:_**
1) **Healed latent infection** —\> fibrosis and + PPD (type IV HSR)
2) **Systemic infection** (miliary Tb) —\> fulminant multiorgan failure
3) **Reactivation Tb** —\> d/t immunosuppression —\> TNF activation; affects **upper lobes** leading to **hemoptysis, night sweats** (classic sx), Pots disease, meningitis, tuberculoma
131
Characteristics of Mycobacterium avium complex; how is it acquired?
Who does it affect most often?
Causes what?
- Acquired from environment
- Key player for immunocompromised
- AIDS pts with CD4 \<50, elderly smokers
- Causes nodularities and bronchiectasis in middle aged non-smokers
- Lymphadenitis in kids
132
Characteristics of Ureaplasma urealyticum?
Causes what?
- Pleomorphic, no cell wall, requires cholesterol, **urease (+)**
- Non-gonococcal **urethritis**: burning dysuria, yellow mucoid urethral discharge
133
Characteristics of *Mycobacterium leprae?*
Main reservoir?
Thrives in?
* Acid-fast (carbol fuscion stain)
* Non-motile
* Facultative intracellular
* Mycolic acids in cell wall
* Thrives in **cool temps**
* **Main reservoir:** armadillos
134
What are the 2 clinical presentation(s) with *Mycobacterium leprae* infection and the features of each
**Tuberculoid:** Th1 cell-mediated — macrophage-contained; **well-demarcated** skin plaque; **localized superficial**, unilateral **skin** and **nerve** involvement
**Lepromatous:** Th2 cells, but **no cell-mediated response.** Not contained in macrophages and high chance of human-human transmission.
- **G****love/stocking neuropathy**, lesions on**extensor surfaces**, profound facial deformity (leonine facies),**saddlenose deformity**, and internal testicular damage (leading to**infertility**)
135
Characteristics of *Borrelia burgdorferi?*
Vector, reservoir and obligatory host?
- Spirochete
- Microaerophilic
- Wright stain and Giemsa stain + ELISA and Western blot (CMMRS)
**- Ixodes tick** is vector; reservoirs are **mice**, obligatory hosts are deer
136
Clinical features of Borrelia burgdorferi infection?
Describe each stage.
1. **Early localized stage:** Erythema chronicum migrans (bullseye rash), fever, chills
2. **Early disseminated stage:** mutliple smaller ECMs, Heart block (myocarditis), bilateral Bell’s palsy, brief attacks of arthritis of large joints (knee)
3. **Late stage:** chronic arthritis, encephalopathy
\*Lyme Disease
137
Characteristics of *Leptospira interrogans?*
Endemic where?
Where is it found and how do people get infected?
- Spirochete - "Ice tong" or "question mark shaped"
- Aerobic
- Endemic in tropical areas (i.e., Hawaii)
- Found in water contaminated with animal urine; associated with **water sports**
138
Clinical features of *Leptospira interrogans* infection.
Describe each phase?
What is the severe illness it may cause?
1) **L****eptospiremic phase:**bacteria invade the**blood**and**CSF**and cause**abrupt onset**of**high fever**, headache, malaise, and severe myalgias; classically the**conjunctiva are red**and pt has**photophobia**
2) **I****mmune phase:**appearance of**IgM Ab,**pts may develop meningismus; CSF exam reveals an**elevated WBC count**
- **Weil's disease:** or **infectious jaundice**, involving **renal failure**, hepatitis w/ jaundice, mental status changes, and **hemorrhage** in many organs
139
Characteristics of *Treponema pallidum*
How is diagnosis of infection made?
Transmitted?
Reservoir?
- Spirochete
- Dark field microscopy needed for direct visualization
- Use **VDRL or RPR** (**non-specific**) followed by **confirmatory FTA-Ab** test (**specific**)
- Reservoir = humans (only)
- Sexually (STD) --\> Causes syphilis
140
Clinical manifestations of adult syphilis; primary and secondary.
**Primary:** painless genital chancre (skin ulcer) erupts **3-6 weeks** at site of inoculation; chancre is firm, ulcerated painless lesion w/ a punched-out base and rolled edges; resolves over **4-6 weeks**
**Secondary:** untreated patients enter the **bacteremic stage** after about 6 **weeks,** becomes **systemic**: maculopapular rash on **palms/soles** within weeks to months, **condyloma latum (wart-like lesions)** on mucous membranes (i.e., vulva and scrotum); generalized LAD, weight loss, fever and almost any organ can be affected
141
Clinical features of congenital syphilis
- Anterior bowing of tibia (saber shins)
- Saddle nose
- Hutchinson teeth and Mulberry molars,
- Deafness,
- Widespread rash, rhinitis, and hepatosplenomegaly (characteristic of **early congenital syphilis**)
142
What is the Jarisch Herxheimer rxn?
When you first treat syphilis with penicillin, symptoms may worsen prior to improving — fever, chills, HA
143
Characteristics Chlamydia trachomatis
- Gram-negative obligate intracellular
- **No** peptidoglycan or muramic acid (cannot grow on media)
- Giemsa stain to visualize
- Dx with NAAT test (PCR)
- Exists in 2 forms: Elementary body and Initial body
144
Clinical features of 3 groups of Chlamydia trachomatis
Is the most common and leading cause of what?
**A-C:** Blindness (**leading cause** worldwide!) - \*A-B-SEE\*
**D-K:** characteristic **watery** discharge, cervicitis, epididymitis, **PID**, neonatal transfer—\> conjunctivitis, pneumonia (**most common STD**)
**L1-L3:** lymphogranuloma venaerum - painless genital ulcer, tender LAD in inguinal region
145
Complications of *C. trachomatis* infection
**- Reactive arthritis (Reiter’s syndrome)** “Can’t see, can’t pee, can’t climb a tree” — conjunctivitis, urethritis, arthritis
**- Fitz Hugh Curtis syndrome** (perihepatitis): infection of **liver capsule** w/ sx's of RUQ pain
146
Clinical features of Chlamydia pneumoniae and psittaci?
How are they transmitted?
**Pneumoniae** species is TWAR; causes atypical pneumonia in young adults; transmitted via **respiratory route**
**Psittaci** causes pneumonia 1-3 weeks after exposure; transmission by **bird droppings** or **dust from feathers** (think parrots, vets, and workers in poultry slaughterhouse or pet-shop)
147
Characteristics *Coxiella burnetti*
Reservoir and transmission
What does it cause and the classic findings?
Complications caused by this infection?
- Gram negative rod
- Obligate intracellular
- Contained in **spores** in animal poop (resistance to heat, exists extracellularly, and non-arthropod transmission)
- Aerosol transmission
- Causes **Q fever** — abrupt onset of fever, soaking sweats, headache, viral-like pneumonia (cough), w/ **NO RASH!**
**- Complication:** granulomatous **hepatitis** and culture negative **endocarditis**
148
Clinical features of Gardnerella vaginalis?
What are the classic signs and how is it diagnosed?
- Gram negative bacillus that causes **bacterial vaginosis** (bacterial overgrowth of normal **anaerobic** flora creates a suitable enviornment for growth *Garnerella*)
- Burning, pruritis (itching) of labia, dysuria (burning), and a copious, **foul-smelling** vaginal discharge w/ **fishy odor**
- Dx via KOH whiff test or **Clue cells** (epithelial cells coated in bacteria)
149
Characteristics of *Mycoplasma pneumoniae*
What is seen on CXR?
- **NO** cell wall - won’t gram-stain
- Grows on **Eatons agar**
- **Only bacteria with CHOLESTEROL in cell membrane**
- CXR reveals **streaky infiltrate**, which usually looks worse than the clinical sx's and PE suggests
150
Clinical features of *Mycoplasma pneumoniae* infection?
Who's most often affected?
Diagnosed how?
Associated with what other pathologies?
- Causes “**walking pneumonia”** with patchy infiltrate and **tracheobronchitis**
- Increased incidence in young adults and military recruits - close quarters
- Dx via **cold agluttinins** (clumped RBCs in cold temps) - **IgM**, may also see bullous meringitis on PE
- Associated with **erythema multiforme** and **Steven Johnson syndrome**
151
General *Rickettsia* morphology
Tropism for?
Diagnose how?
- Gram-negative (**coccobacillary**) but doesn’t stain well (pleomorphic)
- Obligate intracellular
- **Tropism** for **endo**thelial cells that line blood vessels
- Unable to produce **NAD or CoA**; rely on eukaryotic cells
- **Dx** with **Weil Felix agglutination** test; Cultiure: chick yolk sac; Serology
152
Clinical features of early undetermined Rickettsia infection?
Prodromal headache and fever, vasculitis/rash
153
Clinical features of *Rickettsia prowazekii* infection?
How is it transmitted?
What type of Typhus?
- Rash **starting on trunk** and spreading to extremities, **SPARES hands/feet**; myalgia, arthralgia, encephalitis, dizziness, confusion, coma
- Affects military recruits and POWs
- Spread by louse poop that gets into scratches
- Causes **EPIDEMIC typhus** (OX-19) — widespread rampant outbreak
154
Clinical features of *Rickettsia rickettsii* infection
How is it transmitted and what is the reservoir?
Weil-Felix Ag findings?
- Rocky Mtn Spotted Fever, **OX-19, OX-2** (Weil-Felix Ags)
- Transmission via dermacentor ticks (wood or dog ticks)
- Reservoir = dogs, rabbits and rodents
- Rash takes 2-14 days to develop, **extends from extremities —\> centrally**; headache, fever, myalgias
155
Clinical features of Rickettsia akari infection?
Weil-Felix Ags?
Reservoir and transmission?
- **Rickettsial pox:** mild, self-limiting fever; blister at bite site then vesicular rash and headache — **Weil Felix NEGATIVE**
- Reservoir = house mice
- Transmission = mites (live on house mice)
156
What condition is very similar to Rocky Mtn Spotted Fever but is NOT associated with a rash?
Erlichiosis
157
A male smoker presents with pneumonia, high fever, diarrhea, hyponatremia, and neurological symptoms, including headache and confusion.
What organism and disease do you suspect?
Gram positive or negative?
Legionella (Gram negative) --\> Legionnaire's Disease
158
How is Francisella tularensis transmitted?
Main reservoir for this bacteria?
Other modes of transmission?
- Transmitted via **Dermacentor tick**
- Main reservoir = **rabbits**
- Can be **aerosolized** and potentially used in **bioterrorism**
159
Once Francisella tularensis is acquired what occurs?
- Causes **painful ulcer**
- Macrophages pick it up and travel through lymph system to the reticulo-endothelial organs
- Causes **granulomas w/ caseating necrosis** in the **reticulo-endothelial organs (spleen, liver, and LNs)**
- Regional lymphadenopathy
160
What type of bacteria is Francisella tularensis?
Gram negative coccobacilli
161
What type of bacteria is Pasteurella multocida?
Positive lab tests?
Grows well on what agar?
Demonstrates what staining?
- Gram negative
- **Oxidase positive**
- **Catalase positive**
- **5% sheeps blood agar**
- **Bipolar staining (safety pin staining)**
162
Main reservoir for Pasteurella multocida?
How is it transmitted?
Virulence factor?
- Respiratory tract of small animals - Dogs and cats
- Transmitted via **dog and cat bites**
- **Capsule** is its VF
163
What occurs after infection with Pasteurella multocida?
What are long-term consequences?
- **Cellulitis** around bite withing **24 hours of infection**
- May develop into **necrotizing fascitis** or **OSTEOMYELITIS**
164
What are the toxin mediated diseases caused by Staph Aureus?
Toxin responsible for each?
- **Scalded skin syndrome/impetigo**: exfoliative toxin (protease)
- **Toxic shock syndrome:** TSST a superantigen
- **Staph food poisoning**: rapid onset w/ vomiting and associated with meats and mayonnaise left out too long
165
How do differentiate Group A and Group B streptococcus using Bacitracin?
- Group **A = Bacitracin SENSITIVE**
- Group **B = Bacitracin RESISTANT**
166
Which tests allows for us to distinguish Streptococcus Agalactiae (Group B) from all other strep?
cAMP test **postive** --\> Group B plated with S. aureus it has a **increasing zone of hemolysis**
167
What morphology will some RBCs have in *Shigella* infection?
Aggregates of platelets protruding from endothelium, lyse RBCs as they pass by, cutting some in half ---\> **Shistocytes! (look like helmets)**
168
Primary cause of meningitis in infants from 3-36 months?
*Influenza **type b***
169
What does a false positive PPD skin test indicate?
Some people from other countries may have had **BCG vaccine**
170
What is Pott's disease?
Tuberculosis infection affecting the **vertebrae,** usually in **thoracic** and **lumbar spine** ---\> **destroying IV discs** and then **adjacent vertebral bodies**
171
What is Tertiary Syphilis?
How long does it take to develop and what are the 3 general categories of pathologic finidings?
- Develops over **6-40 years**, w/ slow inflammatory damage to organ tissue, small BVs, and nerve tissue: grouped into **3 general categories.**
1) **Gummatous**: occurs **3-10 yrs** after 1° = localized granulomatous lesions, which necrose and become fibrotic
2) **CV syphilis**: occurs at least **10 yrs** after 1° = aneurysm in ascending aorta or aortic arch; chronic inflammatory destruction of **vasa vasorum**
3) **Neurosyphilis:** subacute meningitis, meningovascular syphills (cerebrovascular occlusion), **Tabes dorsalis** (damage to posterior columns and dorsal roots) leading to **odd gait**, general paresis, and the **A****rgyll-Roberston pupil =** accomodating, but non-reactive.
172
Describe the life cycle of *Chlamydia* and its 2 forms.
- **Elementary body**: metabollically inert (does not divide), infectious particle, attaches to and enters (via endocytosis) columnar epithelial cells that line mucous membranes
- **Reticulate body (initial body):** once inside host cell, inhibits phagosome-lysosome fusion, grows in size and forms IB, can reproduce via binary fission and uses host ATP
- Host cell liberates the EB, which can now infect more cells
173
*C. trachomatis* can be passed to babies during delivery causing what infections?
What is the timeline for these symptoms and how can it be distinguished from gonorrhea?
How is diagnosis of each infection made?
- **Inclusion conjunctivitis:** purulent yellow discharge and swelling of eyelids usually **5-14 days** after birth
- Dx made by demonstating basophilic **intracytoplasmic inclusion bodies** in cells taken from scrapings
**- Infant pneumonia:** usually occurs at **4-11 weeks** of life; initally presenting w/ upper respiratory sx's followed by rapid breathing, cough, and respiratory distress (**gonorrhea** presents **2-3 days** after birth)
174
What is special about the Rickettsial disease caused by *Coxiella burnetii?*
Only ricketssial disease that causes pneumonia and in which there is **NO rash!**
175
What is the HACEK group of bacteria that are known to cause endocarditis?
**H**aemophilus species
**A**ctinobacillus species
**C**ardiobacterium species
**E**ikenella species
**K**ingella species
176
Which organism is the #1 cause of bacterial bronchitis and pneumonia in teenagers and young adults?
*Mycoplasma pneumoniae*
177
What kind of infection is caused by *Rickettsia typhi*?
Reservoir and is transmitted how?
- Causes **endemic** flea-borne typhus: fever, headache, and a flat and sometimes bumpy (maculopapular) rash. Milder sx's than **epidemic typhus** (caused by *Rickettisia prowazekii)*
- Reservoir = rodents
- Transmission = rat flea (*Xenopsylla cheopi*)
178
What are the 4 D's of Botulism?
1. Diplopia (double vision)
2. Dysarthria (difficulty talking)
3. Dysphonia (abnormal voice quality, pitch or intensity)
4. Dysphagia (trouble swallowing)
179
What is the JONES criteria for Rheumatic Fever?
J = joints (polyarthritis)
O = Myocarditis and pericarditis
N = nodules on extensor surfaces
E = Erythema marginatum
S = Sydenham's Chorea
180
What is caused by *Klebsiella granulomatis?*
Where is this infection endemic?
What are the signs and symptoms?
- Granuloma inguinale
- **Endemic** in **rural areas** of some **developing countries**
- Begins as a raised papular lesion of the genitalia
- Eventually ulcerates and develops abundant granulation tissue, mainfesting as a **painless**, beefy red ucler that bleeds readily on contact
181
What is caused by *Haemophilus ducreyi?*
Where is it most commonly seen?
- **Chancroid** = **Painful** genital ulcer **with exudate**, **inguinal adenopathy**
"It's so painful, you "**do cry"**
- Most common in tropical and subtropical areas among lower SE groups. One of the most common causes of genital ulcers in **Africa** and **SE Asia**
182
Morphology of actinomyces israelii
Gram+ filamentous branching rod
Obligate anaerobe
183
Clinical manifestations of actinomyces israelii infection?
Part of which normal flora?
What is the catalyst for infection?
Part of normal flora of oral cavity
Jaw trauma (such as with dental work) causes infection.
Starts as a lump and proceeds to form abscess.
Can then infect sinus tracts and drainage of yellow sulfur granule material
184
Morphology of Nocardia asteroides
Gram+ filamentous branching rod
Weakly acid-fast d/t mycolic acids
Obligate aerobe
Catalase+
Urease+
Found in soil but does **NOT** form spores
185
Clinical manifestations of Nocardia asteroides; who is primarily affected?
What are the 3 main infection sites
Primarily affects immunocompromised —\> HIV pts, transplant pts, pts on glucocorticoids
Affects men \> women
3 main sites of infection:
- Pulmonary: PNA with lung abscesses (cavitary lesions)
- CNS: brain abscesses
- Cutaneous: pyogenic, indurated lesions (at risk when dirt gets in wounds)
186
Why is it clinically significant to note if organisms are catalase+?
People with chronic granulomatous disease (CGD) are at **increased risk** of infection with catalase+ organisms
187
A 52 yo patient with diabetic neuropathy is admitted to the MICU. He begins spiking a fever the day before while a patient in the dialysis unit. He is now hypotensive. You diagnose a urinary tract infection due to a urea-splitting agent.
Which bacteria is most likely in this setting?
Proteus mirabilis
188
What are the characteristics of *Acinetobacter baumannii**?*
Where are they most often seen and what kind of infections do they cause?
Why are they so unique in the healthcare setting?
- Aerobic, gram-negative
- Can survive for extended periods on enviornmental surfaces, increasing its transmission in healthcare settings
- **Pneumonia**, Line-related bacteremia, UTI, **burn/wound infections**, eye infections
- At times **may appear gram-positive** and may even be **misidentified** as ***Neisseria* species**
189
Which bacteria is an obligate aerobe, gram-negative rod and produces a green fluorescent pigment (pyoverdin) and blue pigment (pyocyanin), which gives colonies and infected wound dressings a greenish-blue coloration?
*Pseudomonas aeruginosa*
