Microbiology > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

Anaerobes

A
  • infections are close to mucosal surface
  • foul odor
  • produce large quantities of gas
  • black color or brick-red fluorescence
  • anaerobic infections are usually polymicrobial
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2
Q

G+ spore-forming rods

A

Clostridium genus

catalase negative (unlike bacillus)

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3
Q

C. perfringens

A
  • boxcar shaped
  • double zone of beta hemolysis
  • Type A: ingestion of toxin that causes diarrhea and cramps
  • Type C: bloody diarrhea with necrotic inflammation of the small intestine (can be fatal)
  • can cause myonecrosis aka gas gangrene
  • most common isolate in blood cultures
  • Egg yolk agar: opaque zone around colony (lecithinase)
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4
Q

C. botulinum

A
  • from canned foods
  • causes flaccid paralysis
  • botulism
  • ingestion of preformed botulin toxin, babies eating honey, wounds
  • Toxin A is used for Botox
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5
Q

C. tetani

A
  • heavy swarming with terminal spores
  • neurtotoxin inhibits nuerotransmitters
  • tetanus
  • spastic/rigid paralysis
  • TDaP vaccine
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6
Q

C. difficile

A
  • most common isolate in antibiotic-associated diarrhea
  • can cause colitis
  • develops because normal flora is destroyed by antimicrobials
  • nosocomial
  • test for toxin production
  • CCFA is selective: yellow round glass colonies
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7
Q

G+ non-spore forming rods

A

Actinomyces
Bifidobacterium
Propionibacterium (P. acnes is a frequent contaminent in blood cultures)

-all three can cause actinomycosis which is when sinus tracts erupt to the surface and drain pus that contains sulfur granules

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8
Q

G- anaerobic bacilli

A

Bacteroides (most common)
Prevotella
Porphyromonas
Fusobacterium

G- anaerobic cocci (veillonella)

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9
Q

Bacteroides fragilis

A
  • # 1 NF bacteria in human colon
  • # 1 causative agent in peritonitis and intra-abdominal abcesses

B. ureolyticus may pit agar

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10
Q

Prevotella melaninogneica

A
  • # 1 bacteria of gingiva (also in vagina)

- turns to a brown-black color over 2-3 weeks

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11
Q

Porphyromonas

A
  • normal flora of the mouth & GU tract

- head/neck infections

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12
Q

Fusobacterium

A
  • oral flora, also in GI, GU, and URT
  • sores, foot ulcers, etc
  • Lemierre’s disease- can cause clots in jugular vein
  • both species fluoresces chartreuse
  • resistant to vancomycin
  • F. nucleatum- long/thin with pointed ends. lipase negative.
  • F. necrophorum- has rounded ends. lipase positive.
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13
Q

Anaerobic cocci

A

Peptostreptococcus

  • brain abscesses, meningitis, pneumonia, and gingivitis
  • SPS test: Peptostreptococcus is sensitive & Peptoniphilus is resistant
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14
Q

Anaerobic testing

A
  • best cultures are tissue biopsy or needle aspiration
  • rapid processing due to drying out and exposure to O2
  • PRAS media to isolate since most anaerobic infections are polymicrobial
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15
Q

Anaerobic chambers

A
  • H2 (5-10%)
  • CO2 (5-10%)
  • N2 (80-90%)
  • palladium coated alumina pellets remove any residual O2
  • dessicant absorbs excess water
  • indicator: blue or pink when O2 present
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16
Q

KVLB agar

A

eliminates most Gram negative via kanamycin & most Gram positive via vanco

Kanamycin: sensitivity indicated Bacteroides (except B. fragilis) or Fuso & Veillonella

Vancomycin: sensitivity indicates G+ bacillus or Porphyromonas

Prevotella & B. fragillis are resistant to V & K (black color)

Colistin disc (not on agar): sensitivity indicates same as kanamycin plus Prevotella

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17
Q

BBE agar

A
  • bile

- B. fragilis group

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18
Q

Fluorescence

A
  • Porphyromonas & Prevotella: brick-red
  • Fusobacterium & C. dif: chartreuse
  • Veillonella: red
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19
Q

Spot indole test

A
  • blue-green = positive

- P. acnes is the only one

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20
Q

Spirochetes

A
  • helical shaped
  • unicellular motile bacteria
  • usually treat with doxy or tetracycline
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21
Q

Leptospira

A
  • tightly coiled
  • L. interrogans causes Leptospirosis (Swineherd’s disease)
  • severe systematic disease = Weil’s disease
  • zoonotic disease, excreted in urine
  • Fletcher’s agar
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22
Q

Borrelia

A
  • loosely coiled
  • anthropod borne (Ixodes tick)
  • Kelly medium
  • microaerophillic
  • requires fatty acids for growth
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23
Q

B. recurrentis

A
  • relapsing fever
  • can be seen in PB
  • death of spirochetes can cause sudden endotoxin release (Jarisch-Herxheimer rxn = flu-like symptoms)
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24
Q

B. burgdorferi

A
  • Lyme’s disease
  • Stage 1: bulls-eye rash
  • Stage 2: arthritis, meningitis, lesions
  • Stage 3: chronic lesions, neurological symptoms, permanent disability
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25
Treponema pallidum
- Syphillis | - can cross placenta (all treponemals can)
26
T. pallidium: pertenue
- Yaws - nonvenereal - lesions on face
27
T. pallidum: endemicum
- Endemic syphillis (bejei) - contact with contaminated eating utensils - resembles Yaws
28
T. pallidum: carateum
- Pinta | - ulcerative/papulo lesions that depigment skin
29
Syphillis
- gay male sex - Primary: chancre at infection site (penis or vagina/cervix) - contains spirochetes that can be seen in dark field microscopy - Secondary: widespread macular rash (syphilitic roseola) on palms/soles of feet and condylomata kata (most gray-white plagues with spirochetes) - Latent: pt is asymptomatic but still infectious - Tertiary (late): late complications such as CNA issues - Congenital- intrauterine that causes facial abnormalities such as Hutchinson's teeth
30
Chlamydia
- obligate intracellular parasites | - two forms: elementary body (infectious phase) and reticulate body (replicate/non-infectious phase)
31
C. trachomatis
- most common bacterial STD in the US - males: urethral discharge, urethritis, conjunctivitis, prostatitis, etc. - females: cervicitis, PID, conjunctivitis, discharge, can cause infertility - often asymptomatic** - other infections: neonatal (Reiter syndrome, passed through birth canal), Lymphogranuloma Venereum (bubo formation, genital/anal papule), Trachoma (blindness..#1 cause of avoidable blindness) - humans only reservoir - to dx, mucosa scraping (1st morning urine/vaginal swabs are best)
32
C. pneumoniae
- TWAR - via respiratory droplets - endotoxin - life cycle promotes infection - survive in macrophages - cause recurrent or persistant infections
33
C. psittaci
- bird chlamydia - parrot fever - pneumonia in humans - via respiratory droplets
34
Rickettsiae
- obligate intracellular bacteria - transmission through ticks - Spotted fever & Typhus group
35
Spotted Fever Group
- R. rickettsii: Rocky Mt Spotted Fever - ticks: D. variabilis & D. andersoni - flu-like symptoms with rash on ankles/wrist- NOT FACE - R. konorii: Boutonneuse Fever aka Mediterranean spotted fever - reservoirs are ticks and dogs - rash on palms/soles of feet/body/face - Taches noires: black spots at primary site of infection
36
Typhus group
- R. typhi: endemic typhus aka murine typhus - oriental rat/cat flea - flea poops on skin and scratching infects the bite - R. prowazekii: epidemic louse-borne tyhpus aka Brill-Zinsser disease - human louse/squirrel flea/louse - rash all over-including face
37
Rickettsialpox
- R. akari - reservoir is house mouse - vector is mouse mite - papules form at bite and progresses to a pustule - rash everywhere except for palms/soles
38
Scrub Typhus
- causative agent is Orientia tsutsugamushi - vector- chigger - reservoir is rat - tache noire at site of inoculation - rash IS NOT on face, soles, palms
39
Anaplasmataceae family
- Ehrlichia: dogs infected with brown dog ticks - asymptomatic in humans - can form morulae in cells (in WBC) - Lone star tick
40
Coxiella
- C. burnetti - Query fever - livestock are reservoirs - bioterrorism agent
41
Mycoplasma
- smallest free-living organisms in nature - do not possess cell walls so cannot Gram stain and extremely sensitive to drying - resistant to cell wall antibiotics (PCN) - slow growing, fastidious (need cholesterol & fatty acids) - dacron swab or freeze @ -70 degrees C - spread via close contact (aerosols) - look like fried eggs on agar
42
M. pneumoniae
bronchitis/pharyngitis - walking pneumonia (atypical pneumonia- usually asymptomatic) - adheres to oropharynx cells - isolation always indicates pathogenicity - typically not cultured- uses serology - rx = erythromycin or Z-pak
43
M. hominis
- urogenital - requires arginine - normal flora-opportunistic pathogen - rx = clindamycin
44
ureaplasma
- urogenital infections - meningitis of newborns - urethritis in men - requires urea - rx = erythromycin
45
ID of Mycoplasma
- on A8 agar: look for fried egg appearance for M. hominis & irregular shaped colonies for ureaplasma - in liquid media- look for pH change which will turn pink
46
Mycobacteria
- non-motile - non-spore forming - cell wall has high lipid content (mycolic acid) so its resistant to Gram stain - aerobic - requires complex media - divided into two groups: M. tb complex (both are catalase neg and inhibited by NAP) & nonTb mycobacteria (NTMs) and then M. leprae is by itself
47
M. bovis
- MTB complex - primary in cattle - transmission via ingestion of contaminated milk or airborne - inhibited by T2H and pyrazinamidase (differentiate from M. TB) - niacin neg - doesnt reduce nitrate
48
M. tuberculosis
- MTB complex - primary TB - transmitted via airborne droplet - bacteria gets phagocytsed and can still multiply (+PPD test) - reactivation can occur in advanced age, immunocompromised, and malnutrition pts (night chills common symptom) - slow grower: raised dry rough appearance - cord factor - optimal growth: 35-37 degrees - only non-pigment producer that is positive niacin accumulation and reduces nitrate - positive pyrazinamidase - converts to nicotinic acid (yellow color) - treatment: 9 course regimen of isoniazid & rifampin
49
Miliary tb
spread of bacteria from lungs to bloodstream (M. tb)
50
M. avium/M. intracellulare
- most common NTM causing tb in the US - pulmonary disease that resembles TB - slow growing - associated with HIV/AIDS pts - growth in T2H media M. avium subsp. paraTB: Johne's disease- chronic diarrhea in livestock
51
M. kansasii
- 2nd most common cause of NTM lung disease in US - slow grower - photochromogenic - reduces nitrate** - produces pyrazinamidase
52
Photoreactivitiy
photochromogens: carotene pigment upon exposure to light scotochromogens: pale yellow to orange color in dark or light nonchromogenic: buff of lack of color
53
M. genavense
- AIDS pts | - enteritis, genital, and soft tissue infections
54
M. haemophilum
- immunocompromised pts - not pulmonary - lymphadenitis and nodules (cutaneous)
55
M. malmoenese
chronic pulmonary disease and cervical lymphadenitis
56
M. marinum
-cutaneous infections due to contain with salt water or inadequate chlorinated water aka swimming pool granuloma -positive pyrazinamidase
57
M. scrofulaceum
- cervical lymphadenitis in children - scotochromogen - positive urease (differentiates from M. gordonae)
58
M. simulae
- pulmonary disease in pts with preexisting lung conditions - parts of Texas - photochromogenic and produces niacin
59
M. szulgai
- pulmonary disease similar to TB | - photochromic
60
M. ulcerans
- nodule that develops into ulcers | - nonchromogenic buff colonies
61
M. xenopi
- recovered from hot and cold water temp birds and taps - can grow at 42 degrees - pulmonary - scotochromic
62
M. gordonae
- found in tap water and soil aka tap water bacillus** - found in clinical specimens but not pathogen - scotochromogen
63
Rapid growing species (more than 7 days)
- M. chelonae: M. abscesses group - opportunistic infections - cutaneous - only rapid grower to be be negative for iron uptake - more drug resistance than others in this group - + 3-day arylsulfatase test and will grow on MAC - doesnt reduce nitrate
64
M. leprae
- Hansen's disease (leprosy) - two types - tuberculoid-skin lesions and nerve involvement but spontaneous recovery and - lepromateous- skin lesions and progressive nerve damange that can lead to deformities and can be fatal - person to person transmission - armadillo,mouse feet
65
specimen collection
early morning respiratory specimen on 3 consecutive days (only 2/3 need to be positive for confirmatory)
66
digestion/decontamination
- digestion: liquefy the sample so the bacteria can absorb nutrients in media decontamination: allow the chemical agent to kill non-mycobacterial organisms (mycobacteria survive due to high lipid cellular walls) - samples collected aseptically do not require this (CSF, pleural fluid, joint fluid) - agents: NAOH & acetyl-cysteine
67
Staining
acid fast stain (Ziehl-Neelsen) 1. carbofuchsin while heating 2. acid alcohol (decolorized) 3. methylene blue (counter stain) blue background with red organism** kinyoun stain is the same except without heat
68
Medias
Lowenstein-Jensen media American Thoracic Society media Middlebrook media all contain malachite green which suppresses the growth of G+ organisms
69
BACTEC system
culturing system of mycobacteria amount of labeled CO2 is detected and interpreted as a growth index
70
MGIT
same principle as BACTEC but measures O2 consumption via fluorescence
Microbiology
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