X - Gram-Negative Bacteria Flashcards
Gram (-) diplococci, encapsulated, ferments maltose and glucose, kidney bean-shaped, large polysaccharide capsule, oxidase (+) on chocolate agar
Neisseria meningitidis
Neisseria meningitidis: Location
upper respiratory tract, humans - only natural host
Neisseria meningitidis: Transmission
respiratory droplets, close quarters (military, dormitories, camps)
Neisseria meningitidis: Virulence factors
antiphagocytic polysaccharide capsule, endotoxin (LPS), IgA protease, complement deficiencies in the late-acting complement components (C5-C9)
Neisseria meningitidis: Diseases
meningitis, meningococcemia, Waterhouse-Friderichsen
Most common cause of meningitis among children 2-18 y.o.
Neisseria meningitidis
Fever, headache, stiff neck, increased level of PMNs in spinal fluid
Meningitis (Neisseria meningitidis)
Dissemination of meningococci into the bloodstream, multiorgan disease, consumptive coagulopathy, petechial or purpuric rash (purpura fulminans)
Meningococcemia
Most severe form of meningococcemia, high fever, shock, widespread purpura, disseminated intravascular coagulation, thrombocytopenia, adrenal insufficiency (bilateral hemorrhagic destruction of the adrenal glands)
Waterhouse-Friderichsen
Neisseria meningitidis: Treatment
Penicillin G, Ceftriaxone
Neisseria meningitidis: Prevention
capsular polysaccharide (A, C, Y, W-135) coupled to a carrier protein (diphtheria toxoid) to enhance immunogenicity, Rifampin chemoprophylaxis for close contacts
Gram (-) diplococci, ferments glucose only, kidney bean-shaped, insignificant capsule, oxidase (+) on Thayer-Martin medium
Neisseria gonorrhoeae
Neisseria gonorrhoeae: Location
genital tract
Neisseria gonorrhoeae: Transmission
sexual contact, passage through the birth canal
Neisseria gonorrhoeae: Virulence factors
pili, lipo-oligosaccharide (LOS), complement deficiencies in the late-acting complement components (C5-C9), usual co-infection with C. trachomatis
Neisseria gonorrhoeae: Localized
ophthalmia neonatorum, gonococcal urethritis, pelvic inflammatory disease
Neisseria gonorrhoeae: Disseminated
septic arthritis
Purulent conjunctivitis in newborns
Ophthalmia Neonatorum
Most common cause of urethritis
Neisseria gonorrhoeae
Urethritis and epididymitis in men
Gonococcal Urethritis
Most common cause of PID
Neisseria gonorrhoeae
Complications of PID
sterility, ectopic pregnancy, chronic pelvic pain dyspareunia, Fitz-Hugh-Curtis
Violin-string adhesions, complication of PID
Fitz-Hugh-Curtis
Most common cause of septic arthritis in sexually active adults
Neisseria gonorrhoeae
Arthritis, tenosynovitis, pustules on the skin
Septic Arthritis (Neisseria gonorrhoeae)
Neisseria gonorrhoeae: Treatment
Ceftriaxone + Doxycycline (C. trachomatis co-infection)
Neisseria gonorrhoeae: Prevention
barrier contraception, treat sexual partner, erythromycin ointment or silver nitrate to prevent conjunctivitis
Cause culture (-) subacute bacterial endocarditis in patients with pre-existing heart disease
Eikenella corrodens, Kingella kingae
HACEK Organisms
Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae
Gram (-) coccobacillary rods, enriched chocolate agar, polyribitol phosphate capsule, requires factor X (hemin) and V (NAD) for growth, satellite phenomenon around S. aureus
Haemophilus influenza type B
Haemophilus influenza type B: Location
upper respiratory tract
Haemophilus influenza type B: Transmission
respiratory droplets
Haemophilus influenza type B: Pathogenesis
type b (polyribitol phosphate), IgA protease, children 6-12 mos. (decline in maternal IgG and immature immune system)
Sinusitis, otitis media, pneumonia, meningitis, epiglottitis, COPD exacerbations
Haemophilus influenza type B
Most common cause of epiglottitis, cherry red epiglottis, thumb sign
Haemophilus influenza type B
Most common cause of COPD exacerbations
Haemophilus influenza type B
Laryngotracheobronchitis (Croup): Etiology
Parainfluenza Virus 1 & 2
Laryngotracheobronchitis (Croup): Radiographic Sign
Steeple Sign
Laryngotracheobronchitis (Croup): Treatment
Racemic Epinephrine
Haemophilus influenza type B: Treatment
Ceftriaxone
Haemophilus influenza type B: Prevention
HiB vaccine containing te type b capsular polysaccharide conjugated to diphtheria toxoid (2-18 mos.)
Gram (-) rods, Bordet-Gengou/Regan-Lowe agar, whooping cough
Bordatella pertussis
Bordatella pertussis: Location
upper respiratory tract
Bordatella pertussis: Transmission
respiratory droplets
Bacterial Croup: Etiology
Bordatella pertussis
Bordatella pertussis Virulence Factors: Mediates attachment
Filamentus Hemagglutinin
Bordatella pertussis Virulence Factors: Causes ADP-ribosylation and lymphocytosis
Pertussis Toxin - inactivates Gi (turns off the “off button”)
Bordatella pertussis Virulence Factors: Inhibits phagocytic activity
False Adenylate Cyclase
Bordatella pertussis Virulence Factors: Damages ciliated cells, causes whooping
Tracheal Cytotoxin
Paroxysmal pattern of hacking coughs, accompanied by production of copious amounts of mucus, cough ends with an inspiratory “whoop”
Pertussis (Tuspirina)
Pertussis: Incubation
7-10 days
Pertussis: Catarrhal Phase
1-2 weeks
Pertussis: Rhinorrhea, malaise, fever, sneezing, anorexia, best time for blood CS
Catarrhal Phase
Pertussis: Paroxysmal Phase
2-4 weeks
Pertussis: Repetitive cough with whoops, vomiting, leukocytosis
Paroxysmal Phase
Pertussis: Convalescent Phase
3-4 weeks
Pertussis: Diminished paroxysmal cough, development of secondary complications (pneumonia, seizures, encephalopathy)
Convalescent Phase
Bordatella pertussis: Treatment
Erythromycin
Bordatella pertussis: Prevention
acellular vaccine combination with diphtheria and tetanus toxoids (DTaP)
Gram (-) rods, poorly gram staining, silver stain, charcoal yeast agar (iron, cysteine), airconditioning, facultative intracellular bacteria, rapid urinary antigen test
Legionella pneumophila
Facultative Intracellular Bacteria
Salmonella, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia
Legionella pneumophila: Location
environmental water sources
Legionella pneumophila: Transmission
aerosol from water source (no human-to-human transmission)
Legionella pneumophila: Sole virulence factor
Endotoxin
Replicates intracellularly, eliminated by cell-mediated immunity, inhibits lysosomal fusion
Legionella pneumophila
Legionella pneumophila: Risk Factors
old age, smoking, high alcohol intake, immunosuppression
Pneumonia, confusion, non-bloody diarrhea, hyponatremia, proteinuria, hematuria
Atypical Pneumonia (Legionella pneumophila)
Mild, flu-like illness caused by Legionella pneumophila
Pontiac Fever
Legionella pneumophila: Treatment
Azithromycin, Erythromycin
Legionella pneumophila: Prevention
reduce cigarette and alcohol consumption, eliminate aerosols from water sources, high temperatures and hyperchlorination of hospital water supply
Facultative gram (-) rods, lactose fermenter on EMB or MacConkey’s agar, green sheen on EMB agar (metallic sheen), acid slant and acid butt on TSI without H2S, typing by O and H antigens
Escherichia coli
Lactose fermenters
Citrobacter, Klebsiella, Escherichia coli, Enterobacter
Escherichia coli: Location
colon, vagina, urethra
Escherichia coli: Transmission
ascending UTI, neonatal meningitis, fecal-oral
Escherichia coli: Virulence Factors
pili, flagellum (H), capsule (K), endotoxin (O), enterotoxins - HST & HLT (watery diarrhea), verotoxin (Shiga-like) bloody diarrhea in HUS