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level: Gram Negative Bacteria

Questions and Answers List

level questions: Gram Negative Bacteria

QuestionAnswer
NeisseriaUnique Small Gram –ve diplococci Oxidase positive Grow best at 35-37°C, humid CO2 Environment N.Gonorrhea and N.Menigitidis
Why does a vaccine exist for N. meningitidis but not N. gonorrhoeae?N. meningitidis Capsular proteins are used as vaccine N. gonorrhoeae does not have a true capsule Surface proteins of N. gonorrhoeae have not been useful for production of a vaccine
n. gonorrheaGram -ve diplococci Oxidase +ve Cannot grow on nutrient Agar Humans are only natural host 2nd to chlamydia as most common sexually transmitted disease Transmitted primarily by sexual contact Die rapidly if specimen dries
What is the major reservoir of N.gonorrhea?Asymptomatic infected woman (men
n. meningitidisGram -ve diplococci Oxidase +ve mortality rate close to 100% (10% if treated quickly and correctly) transmitted by respiratory droplets among people in prolonged close contact Variable growth on nutrient agar
eikenella corrodensSmall, nonmotile, non-spore forming, gram –ve rods Blood/chocolate agar Capnophilic: 5-10% CO2 Bleach like odor Transmission: bite from infected person (introduction of organism into deep tissue)
kingella kingaegram –ve fastidious, oxidase +ve coccobacilli Resemble Neisseria and reside in oropharynx Septic arthritis in children (2nd to S. aureus) and endocarditis
pasteurellaceae familyHaemophilus and Pastereurella
HaemophilusRequires blood for growth on agar H.influenza - originally thought to be the cause of the influensa Differentiation dependent on X or V factor
Pasteruellafacultative anaerobic, fermentative coccobacilli P. multocida (many-killing) P. canis (dogs) Most human infections from animal contact (bites)
PseudomonasMotile, straight or slightly curved Gram –ve rods, arranged in pairs Aerobic respiration (can use nitrate or arginine as an alternate electron acceptor) Cytochrome oxidase (used to differentiate from enterobacteriaceae) Common in cystic fibrosis patients Produce diffusible pigments for preliminary ID (blue pyocyanin, yellow-green pyoverdin, pyorubin red-brown)
P.aeruginosaPseudomonas External otitis (swimmer's ear) Malignant external otitis: primarily elderly or diabetic ppl, damages cranial nerves and bones, may be life threatening
Acinetobacter spp.Pseudomonas Strictly aerobic, oxidase -ve, plump Gram –ve, coccobacilli Can survive on moisturized and dried surfaces (unusual for gram -ve) Part of normal oropharyngeal flora Most human infections caused by A.baumannii "Can close clinics faster than inspectors"
CampylobacterGram -ve comma shaped microaerophilic rods Causes gastroenteritis (most common cause) and septicemia Lab: elevated tem (42 degrees), microaerophilic (5-7% O2 and 5-10% CO2) C.jejuni, C.coli, C.upsaliensis (contact with dogs)
HelicobacterGram -ve rods Gastic helicobacter and enterohepatic helicobacter
Gastric helicobacterMost important -> H.pylori: gastritis, peptic ulcer and B-cell lymphomas
bordetellaB.pertusis (whooping cough): humans only Inhalation of aerosols Use adhesins to attach to epithelial cells Incubation period: 7-10 days
BrucellaGram -ve, non-fermenting zoonotic (contaminated food, direct contact with infected animal) Non-motile non-encapsulated Facultative or strictly aerobic Complex growth media Predilection for erythritol (breast, uterus, placenta) BSL-3 Antibody detection: IgM initially -> IgG, IgA
LegionellaGram -ve rod (short bacilli) Obligate aerobe Enriched cysteine and iron Dieterle Silver Stain Aerosols