Special Pathogens Flashcards

Question

***_B. mallei Technical Clues_***

Answer 1

* • Gram-negative coccobacilli * • Characteristic very slow growth on SBA and little if any growth * MAC * • Oxidase variable * • Non-motile * • Catalase positive

Answer 2

* B. pertussis is small GNCB * B. parapertussis and B. bronchiseptica are more rod shaped * Bordetella species do not gram stain well * Safranin counterstain should be extended for better visualization * Bordet-Gengou (BG) is a potato-based agar with sheep blood and glycerol * Starch neutralizes toxic materials present in specimen * Does not contain peptones because these may be inhibitory * Cephalexin, methicillin, or oxacillin may be added for selectivity * oShelf life 5 days * Regan-Lowe media contains charcoal and horse blood * Available as semisolid transport/enrichment media and solid media * for isolation * May contain cephalexin and/or amphotericin B for selectivity * Shelf life 4-8 weeks

Answer 3

* Whooping cough * Respiratory infection characterized by paroxysmal cough, posttussive vomiting, and inspiratory whoop * Incubation period: 7-10 days; range 5-28 * 3 stages of disease * 1.Catarrhal: nonspecific cold symptoms (1-2 weeks) * 2.Paroxysmal: severe coughing spells that end in an inspiratory whoop (2-6 weeks) * 3.Convalescent: decreasing frequency of coughs, though viral infections can trigger paroxysms (1-12 weeks) * Cough may last more than 10 weeks * Complications include pneumonia, rib fractures, incontinence, syncope

Answer 4

* Small GNRs or coccobacilli, pleomorphic, X factor independent spp. appear as long filaments * Facultative anaerobes * Non motile and non spore formers * Oxidase positive (in contrast to Enterobacteriaceae * Catalase and nitrate positive * All require preformed growth factors found in blood * X factor heme/hemin (protoporphyrin IX) or * V factor NAD or NADP or * X and V both * With the exception of H. ducreyi and H. aphrophilus, * all need V factor * On BAP grow as satellite colonies around S. aureus * β-hemolytic on horse, bovine or rabbit blood but * NOT on she * ep blood (H. hemolyticus, H. * parahemolyticus and H. pittmaniae) * Growth produces pungent or “mouse-nest” smell * Increased CO2 (5-10%) * Capsule Virulence factor * Serotypes a-f * Haemophilus influenzae serotype b (Hib)

Answer 5

* H. influenzae type b (meningitis, cellulitis * epiglottitis, pneumonia, septic arthritis) * H. aegyptius (Koch-Weeks bacillus, pink eye) * H. influenzae biotype aegyptius (Brazilian purpuric fever) * H. parainfluenzae (endogenous) * H ducreyi (chancroid) * H. aphrophilus (HACEK, endocarditis) * Haemophilus – Blood loving * Require X and V factors found in blood X factor is hemin, hematin * V factor is nicotinamide-adenine dinucleotide (NAD) * All para species – require only V factor * Haemophilus parainfluenzae * Produces X factor, requires V factor * H. aegyptius causes conjunctivitis

Answer 6

* Capsule * Serotypes a a-f * IgA protease * Cleaves IgA on mucous membranes * Outer membrane proteins and lipopolysaccharide ( Not well defined * Antibody to these proteins is somewhat protective * LPS paralyzes the cilia * Can’t clear the lungs * Adherence * Pili and other structures

Answer 7

* Legionnaire’s Disease * Route of infection: aerosol * Symptoms: Cough, shortness of breath, fever, muscle aches, headaches * Onset: 2 -10 days post- exposure * Disease: Pneumonia * Isolation of agent: Possible * Outcome: 5% - 40% mortality * Pontiac Fever * Route of infection: aerosol * Symptoms: Fever, muscle aches * Onset: 24 – 72 h post-exposure * Disease: Flu-like illness * Pathogenicity Factors * Biofilms * Replication within host phagocytic cells * Others: iron acquisition, cytotoxins * Monoclonal subtyping of L. pneumophila * serogroup 1 * MLST – flaA, pilE, asd, mip, mompS, proA genes * AFLP

Answer 8

* Motile, gram-negative rods * Asaccharolytic, amino acids used as energy source * Obligate aerobe * Nutritionally fastidious, L-cysteine dependent * Optimal growth @ 35 * Growth enhanced by iron, humidity * If you pretreat sample, use low pH KCL-HCL buffer, 4 mins, at room temperature or heat at 50°C for 30 mins * Use selective and non-selective media: * VAP or BMPA * BCYEα * Incubate at 35°C, humidity, CO2 * (2-5%) * Read days 1-5 and day 14

Answer 9

* Causes acute, localized infections such as otitis media, sinusitis, and bronchopneumonia * Causes a large amount of lower RT infections in elderly patients with COPD

Answer 10

* Cultured on blood and chocolate agar * White/grey colonies, waxy surface * Hockey puck test – able to push the colony across the plate * Specimen types include: inner ear fluid, sputum, and blood * Key * Not able to ferment glucose, sucrose, maltose, and lactose * Positive DNase * Oxidase Positive * Nitrate Positive * M. catarrhalis is often mistaken for N.catarrhalis * M.catarrhalis strains can tolerate lower temperatures and will grow well at 28˚C

Answer 11

* GN coccal or diplococci, aerobic, non-motile * Growth optimal at 35° with humidity, CO, stimulates growth or maybe obligate for initial isolation * Oxidase positive * Difficult to separate. Usually ID as "Nesseria species" unless isolated from systemic source or pure culture * Choc or BA if sample sterile * Modified Thayer-Martin if non sterile sample

Answer 12

* Neisseria Gonorrhea * Neisseria Menigiditis

Answer 13

* Colony on SBA at 35°C, 18-24hr * Flat or slightly raised, grey to white * Undulate edge may show curling resembling a “Medusa head” * Surface has “ground glass” appearance * “Tenacious” or “sticky” * Non-hemolytic * Large Gram-positive rod * Usually non-encapsulated, often in long chains * Cells are more easily decolorized with age * Oval spores, central to sub-terminal, with no swelling of cell * Rapidly growing, flat, “ground-glass” colonies on SBA * Large Gram-positive, aerobic rods * Non-hemolytic * Non-motile * (Catalase positive)

Answer 14

* Inhalation * Gastrointestinal * Cutaneous

Answer 15

* 32% Neonatal sepsis and meningitis * 31% Febrile gastroenteritis * 26% Sepsis in compromised hosts * Motility described as tumbling end over end is viewed microscopically in a hanging drop preparation and umbrella like when viewed in tube cultures grown at room temperature * Facultative anaerobes * Optimum growth temperature * 30-37°C * Can grow at 4°C

Answer 16

* Gram positive, nonsporeforming, short rods * Rod shaped seen individually or in short chains or may appear as coccobacilli * Difficult to stain and may even appear as gram-negative * Motile at 28C by peritrichous flagella, not very motile at 37C * Buffered Listeria Enrichment Broth * Supplements * Nalidixic acid: inhibits Gram negative spp. * Does not ininhibit Pseudomonas or Proteus spp. * Acriflavine: inhibits many other Gram (+) bacteria, parasites, and fungi * Cycloheximide: inhibits yeasts and molds * Very toxic * Can be substituted by pimaricin (a.k.a. matamycin) * Umbrella Motility * Although all are considered to be potentially virulent, serovars 4b, 1/2b, and 1/2a account for 96% of human disease.

Answer 17

* For C. diphtherias to cause diphtheria an exotoxin must be produced. * It is a heat-labile polypeptide produced during lysogeny of a β phage that carries the "tox” gene. * Alkaline pH of 7.8- 8.0, aerobic conditions, and a low * environmental iron level are essential for toxin production * (occurs late in the growth of the organism). * The toxin inhibits protein synthesis * C. ulcerans toxigenic strains may produce a disease * similar to, but less severe than diphtheria. * J-K Group commonly cause infections in those with * underlying disease. * Diseases include bacteremia, meningitis, peritonitis, wound * infections, etc. * It is becoming more and more of a problem. * C. pseudotuberculosis found in those with exposure to * animals. * Can cause pneumonia or lymphadenitis. * Produces a different exotoxin than C. diphtheriae.

Answer 18

* Gram positive rods * Catalase positive * Non-acid fast * Non-spore forming * Aerobic or facultative anaerobic * Fastidious * Corynebacterium diphtheriae and diphtheroids (look like C. diphtheriae) are Gram positive club shaped rods. * Loeffler‘s agar slant contains serum and egg that enhance the formation of metachromatic granules (polymerized polyphosphoric acid) in C. diphtheriae. Also called Babes-Ernst granules. They are visualized by staining with methylene blue. * A medium containing tellurite should be used to select for Corynebacterium and other gram positive organisms while it inhibits gram negative organisms. Two kinds are used: Cystine tellurite which has a longer shelf life. * Elek plate: To prove that an isolate can cause diphtheria, one must demonstrate toxin production. * Tinsdale medium helps to differentiate amongst the Corynebacterium. Colonies on either appear black or gray due to tellurite reduction. * 3 morphological types of C. diphtheriae are found on tellurite containing media: * Mitis – black colonies with a gray periphery * Gravis – large, gray colonies * Intermedius – small, dull gray to black. * All produce an immunologically identical toxin. * Incubation -35-370 C for 24 hours. * They prefer a pH of 7.8-8.0 for good growth. * They require access to oxygen (poor AnO2 growth). * Biochemistry * Catalase + * Non-motile * C. ulcerans is urease + vs C. dphtheriae which is -; C. pseudotuberculosis is usually +

Answer 19

* Gram-negative coccobacilli or rods; bipolar staining * Nonmotile; Facultatively anaerobic * related to Actinobacter and Haemophilus * Exist in the upper respiratory and GI tract of cats, dogs, domesticated and wild animals * Species of importance : P. multocida, P.haemolytica, P. * pneumotropica, P.ureae * Pasteurella multocida: causative agent in human infection

Answer 20

* Zoonosis, virulent to animals and birds * Fowl Cholera in Poultry * Atrophic rhinitis in Pigs * Shipping fever * Bovine hemorrhagic septicemia * human infections * Local abscess * Meningitis * RT infections * Animal Bites

Answer 21

* Specimens * Swabs from bite wounds * CSF in case of meningitis * Secretions or sputum in case of RT infections * Culture * Blood agar * Chocolate agar * Microscopy Gram staining reveals GNCB * Identification * Cultural and Biochemical tests * Catalase, oxidase + * Indole + * Urease - * ODC + * Growth on MacConkey - * Acid from sucrose, mannitol +

Answer 22

* Thin to slender gram-negative bacilli * Tapered ends * Cytochrome oxidase-variable; gliding motility * “Capnocytophaga” [eater of CO2] * Found as oropharyngeal flora in humans and other primates * Pathogenic for humans * rRNA superfamily V (“Cytophaga – Flavobacterium - Bacteroides” group

Answer 23

* Risk Factors (all) * Dog ownership or contact * Snoggling * Underlying disease * Asplenia * Physician Awareness * Patient Awareness * Laboratory ID * Conventional methods: SLOW

Answer 24

* Pleomorphic, facultatively anaerobic, gram-negative bacterium * Causes two diseases * **Haverhill fever (rare)** * Associated with consumption of contaminated milk, water * High incidence of pharyngitis with vomiting * **Rat-bite fever (common)** * Abrupt onset of high fever, headaches, arthralgia * Rashes develop over extremities (palms, soles) * Diagnosis is dependent upon: * A good medical history (rat or animal exposure) * Using optimal culture conditions to recover bacteria from blood, aspirates, or wounds

Answer 25

* Requires 10% - 20% serum for growth * GNB in chains, filaments, sometimes with bulbous swellings * Growth in thioglycollate broth producing “puff balls” * Positive DFA test with polyclonal ab to S. moniliformis * Rapid ID: * PCR/ESI – MS * 16S rRNA

Answer 26

* ‘Erysipelas’ [a disease] and ‘thrix’ [a hair or thread]; ‘rhusius’ [reddish] and ‘pathus’ [disease]: ‘erysipelas thread of red disease’ * Gram-positive rods [can decolorize easily] * Slender rods with rounded ends; can form long filaments, short chains or in pairs in a “V” formation * Non-motile * Oxidase and catalase-negative * Ecologic habitat: marine fish, molluscs, birds, and farm animals incl. swine, sheep, cattle, and horses * Member of the Fimicutes, family Erysipelothricaceae

Answer 27

* Causes three major syndromes: * Erysipeloid (cutaneous form) resembling cellulitis * Usually on hands or fingers * Well-defined lesion, slightly raised, violaceous zone * Diffuse cutaneous form * More generalized than cutaneous; bullae may form * Fever common plus joint pain * Blood cultures are often negative * Septicemia w/wo endocarditis

Answer 28

* Facultatively anaerobic * On TSA, colonies are very small after 24-48h incubation * Can produce α-hemolysis on BAP * Produces H2S on TSI * “Test tube brush” growth in gelatin stab [no gelatinase] * Most often confused with Listeria

Answer 29

* Cellulitis * Endocarditis, meningitis, arthritis * aquaculture in south east asia

Answer 30

* Gram-positive, β-hemolytic * Non-motile cocci * PYR, CAMP, ADH, and Esc+ * Often mis-ID by conventional/rapid systems * Rapid ID: * 16S rRNA * Cpn60

Answer 31

* Fastidious, Gram-negative bacilli * * Require an increased CO2 (5%-10%) environment * * Indigenous to the oral cavity / upper respiratory tract * * Opportunists in immunocompromised hosts

Answer 32

* Capnophilic, fermentative, non-motile, gram-negative coccobacillus * * Some strains require “V” factor (NAD) * * Oxidase-negative, catalase-negative * * Acid produced from: glucose, maltose, sucrose, lactose, and trehalose * * ONPG-positive * * ADH, LDC, and ODC-negative; urea-negative

Answer 33

* Capnophilic, gram-negative, non-motile coccobacilli * * Fermentative, fails to grow on MacConkey or enteric media * * Oxidase-negative, catalase-positive * * Does not require “X” or “V” factor for growth * * ONPG-negative * * ODC, LDC, and ADH-negative; urea-negative

Answer 34

* Capnophilic (5%-7% CO2), gram-negative but can be gram-variable; non-motile * * Highly pleomorphic, cells may appear swollen with a tteardrop, dumbbell and lollypop-shap)ed cells. Can form rosettes from blood cultures. * * Oxidase-positive, catalase-negative; indole-positive * * Pitting variable on chocolate agar; often requires 48 – 72 hrs growth * * Grows on chocolate agar but not on MacConkey agar

Answer 35

* Fastidious coccobacilli * Gram negative * Grow best with increased CO2 and hemin * Non-motile * Oxidase positive * Nonsaccharolytic * Resemble Moraxella sp. * Catalase-negative * Often produce yellow pigment * 45% of isolates pit or corrode the surface of the agar * In broth media, they may adhere to sides of the tube * and produce granules * Bleach-like odor given off from agar surface

Answer 36

* Coccobacillary to short rods appearing * in pairs and short chains * * Nonmotile * * Nutritionally fastidious * * Oxidase positive, catalase-negative * * Ferments glucose, maltose not sucrose * * May produce yellow-brown pigment * * May pit the agar * * Isolated from blood, bone, joint fluid, urine and wounds * * Most isolates from children \<5 years * * Susceptible to penicillin and most antibiotics

Special Pathogens Flashcards

(62 cards)