Gram Negative and Other Bacteria Flashcards
Neisseria gonorrhoeae
gram-negative diplococci, ferment glucose, no capsule
produce IgA protease
within polymorphonuclear lwukocytes
sexually transmitted
gonorrhea, septic arthritis, neonatal conjuctivitis, PID
Fitz-Hugh-Curtis syndrome
treatment: ceftriaxone (+ azithromycin or doxyxyline for possible chlamydia coinfection)
Neisseria meningitidis
gram negative diplococci, ferment glucose and maltose, capsule
vaccine (none for type B)
transmitted through respiratory and oral secretions
meningococcemia and meningitis, Waterhouse-Friderichsen syndrome
treatment: ceftriaxone or penicillin G
rifampin, ciproflaxacin or ceftriaxone prohylaxis in close contacts
Haemophilus influenzae
small gram-negative coccoid rods
aerosol transmission; produces IgA protease
cause Epiglottitis (“cherry red” in children), Meningitis, Otitis media, Pneumonia (EMOP)
non-typeable strains - mucosal infections (otitis media, conjunctivitis, bronchitis)
capsular (polyribosylribitol phosphate) type B - invasive disease (meningitis, pneumonia)
culture on chocolate agar with factor V (NAD+, produced by S. aureus) and factor X (hematin)
treatment: meningitis with ceftriaxone; rifampin for prophylaxis in close contacts
vaccine - contains type B capsular polysaccharide conjugated to diphtheria toxoid - given at 2-18 months of age (prevent meningitis)
Legionella pneumophila
gram-negative rod - use silver stain
grow on charcoal yeast extract with iron and cysteine
aerosol transmission from environmental water source habitat; no person-to-person transmission
detected by presence of antigen in urine; labs show hyponatremia
Legionnaires’ disease - severe pneumonia, fever, GI and CNS syndrome
Pontiac fever - mild flu-like syndrome
Pseudomonas aeruginosa
gram-negative aerobic rods
non-lactose fermenting, oxidase positive, blue-green pigment, grape-like odor
water source, burn infections
PSEUDO
Pneumonia - in CF with biofilm if chronic
Sepsis - black lesions on skin
External otitis - swimmer’s ear, malignant in diabetics
UTI
Drug use and Diabetic Osteomyelitis
hot tub folliculitis
produces endotoxin (fever, shock) and exotoxin A (inactivates EF-2)
treatment: aminoglycoside + extended-spectrum penicllin (piperacillin, ticarcillin)
E. coli virulence factors
fimbriae - cystitis and pylonephritis
K capsuel - pneumonia, neonatal meniningitis
LPS endotoxin - septic shock
Klebsiella
gram-negative rod, fast lactose fermenter
intestinal flora
causes lobar pneumonia in alcoholics and diabetics when aspirated; nosocomial UTIs
mucoid colonies caused by abundant polysaccharide capsule
red “currant jelly” sputum
Salmonella
gram negative rod, lactose nonfermenter, oxidase negative
have flagella, can disseminate hematogenously
many animal reservoirs
produces hydrogen sulfide
invades intestinal mucosa and causes a monocytic response –> can cause bloody diarrhea
Typhi - typhoid fever, only in humans - rose spots on the abdomen, fever, headache, and diarrhea - can remain in gallbladder and cause a carrier state
Shigella
gram negative rod, lactose nonfermenter, oxidase negative
no flagella; cell to cell transmission, no hematogenous spread
only reservoirs are humans and primates
invades intestinal mucosa and causes PMN infiltration –> often causes bloody diarrhea
Campylobacter jejuni
gram-negative comma shaped
grows in 42 C, oxidase positive
causes bloody diarrhea, especially in children
fecal-oral transmission through food (poultry, raw meat, unpasteurized milk); puppy feces
common antecedent to Guillain-Barre syndrome and reactive arthritis
Vibrio cholerae
gram-negative comma shape
grows in alkaline media, oxidase positive
produces profuse rice-water diarrhea via toxin that permanently activates Gs, increase cAMP
endemic to developing countries
prompt oral rehydration is necessary
Yersinia enterocolitica
gram-negative
causes mesenteric adenitis that can mimic Crohn’s or appendicitis
transmitted from pet feces, contaminated milk or pork
Helicobacter pylori
gram-negative curved rod, urease positive, oxidase positive
causes gastritis and up to 90% of duodenal ulcers
treatment: PPI, clarithromycin, amoxicillin or metronidazole
Leptospira interrogans
spirochete
found in water contaminated with animal urine
causes leptospirosis: flu-like symptoms, jaundice, photophobia with conjuctivitis
prevalent among surfers and in the tropics (Hawaii)
Weil’s disease: severe form with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage, anemia
Borrelia burgdorferi
spirochete - only visualized using aniline dyes (Wright’s or Giemsa)
transmitted by Ixodes tick; natural reservoir is mouse (important to tick life cycle)
common in NE US
3 stages:
1) erythema chronicum migrans, flu-like symptoms
2) neurologic (facial nerve palsy), cardiac (AV nodal block)
3) musculoskeletal (chronic monoarthritis and migratory polyarthritis), neurological (encephalopathy and polyneuropathy), cutaneous manifestations
