Bacteria Flashcards
Staphlococcus aureus
S. aureus
Category : gram + cocci
S & S : Skin infection, osteomyelitis, endocarditis, arthritis, pneumonia, sepsis, food poisoning, toxic shock syndrome (fever, hypotension, rash)
Pathogenesis : Local infection/abscess in punctured skin or entrance throught the resp tract. Capsule, protein A, cell wall, enzymes, hemolysins, toxins A-E
Work-up : Gram stains- looks like grape clusters. Catalase +, coagulase +
Management : *I&D of lesions. *Antibiotics nafcillin, oxacillin and vancomycin are preferred due to penicillin-resistance in some strains.
Streptococcus pneumonia
S. pneumonia
Category : gram + cocci
S & S : Pneumonia, meningitis, sinusitis, otitis media, bacteremia/sepsis
Pathogenesis : Common flora in nasopharynx of healthy individual-general debilitation causes susceptibility to either exogenous or endogenous infection. Capsule, pili, autolysin, pneumolysin, choline-binding protein A
Work-up : Microscopy of swab (blood, pus, sputum, spinal fluid), occurs in pairs, lancet-shaped; blood agar, aerobic
Management : *Prevention: vaccine for susceptible populations
*Infection: antibiotics- penicillin G
-OR- vancomycin, ceftriaxone, cefotaxime (for penicillin resistant strains)
Listeria monocytogenes
L. monocytogenes
Category : gram + rods
S & S : Spontaneous abortion, septicemia, meningitis, neonatal meningitis
Pathogenesis : Enters cells through phagocytosis- changes the cell function to allow intracellular travel.
*Food-born: dairy products, ground meats, poultry.
*From mother to fetus/infant
Work-up : Identified in lab as small colony with tumbling motility. Catalase +.
Management : *Prevention: proper food prep. No vaccine.
*Infection: antibiotics ampicillin and trimethoprim/sulfamethoxazole
Escherichia coli
E. coli
Category : gram - rod
S & S : UTI (dysuria, hematuria, pyuria); bacteremia, sepsis; diarrhea: bloody or watery, abdominal pain; meningitis
Pathogenesis : fecal - oral route; fecal - vaginal route
Work-up : intestinal difficult to detect in lab because E coli is part of normal intestinal flora. Extraintestinal specimens cultured and analyzed in lab.
Management : *Prevention: no vaccine, careful food and water consumption *infection: antibiotic sensitivity testing recommended due to resistance.
*electrolyte balance & water
Vibrio cholerae
V. cholerae
Category : gram - rod
S & S : Cholera: “rice-water” stools, dehydration
Pathogenesis : adheres to small intestine, releases cholera toxin; drinking contaminated water/food; hemolysins
Work-up : grows on blood or MacConkey agar; Oxidase +
Management : *treat for dehydration (electrolytes and fluid) prior to confirmation of illness since pt can die within hours of diarrhea onset.
*Doxycycline
Neisseria gonorrhoeae
N. gonorrhoeae
Category : gram - cocci
S & S : Gonorrhea: urethritis, discharge, urodynia, gonococcal salpingitis, PID; ophthalmia neonatorum: conjunctivitis in newborn; septic arthritis
Pathogenesis : STI; vaginal birth; adhesion of gonococcus to epithelial cells of mucus membranes
Work-up : kidney-bean shaped diplococci visible with neutrophils in urethral exudate. Oxidase +.
Management : Infection: antibiotics (ceftriaxone, erythromycin in newborn eyes just in case); prevention: no vaccine, safe sex
Yersinia pestis
Y. pestis
*The Plague
Category : gram - rod
S & S : Bubonic (buboes in groin, axillae, BP drops –> sepsis and death if not treated); Pneumonic (lungs, purulent pneumonia, incr transmission rate)
Pathogenesis : flea (animal reservoir; humans = dead end host); ingestion of contaminated tissue; respiratory
Work-up : gram-stain, culture from bubo or sputum
Management : 1st = streptomycin or gentamicin, tetracycline as alternative
Clostridium botulinum
C. botulinum
- Food poisoning (botulism)
Category : gram + rod
S & S : blocks acetylcholine –> flaccid paralysis, vomiting, diarrhea
Pathogenesis : ingestion of exotoxin (found in soil, water sediments, improperly preserved food)
Work-up : cultured and ID by anaerobic methods
Management : antitoxin (horse antiserum) - blocks toxin from circulating (blood)
Treponema pallidum
T. pallidum
*Syphilis
Category : gram - spiral
S & S :
primary - within 2-10 weeks: hard, painless ulcer
secondary - <10 weeks 2nd lesion - red maculopapular rash (palms, soles, anogenital regions, armpits, mouth
tertiary - gummas in liver, skin, bones
Congenital - death and spontaneous abortion - development with sphyilis - CNS and structural abnormalities
Pathogenesis : sexual contact; infectious lesion on skin or mucous membrane of genitals; congenital - through placenta
Work-up : not gram stain! darkfield exam = motile spirochetes, serologic tests
Management : Penicillin G, erythromycin, tetracycline
Mycobacterium tuberculosis
M. tuberculosis
*TB
Category : classified as acid-fast Gram-positive bacteria due to their lack of an outer cell membrane.
S & S : lesion in lung:
fibrotic/calcified OR break down, spread via lymph and blood
Pathogenesis : survives and grows in host macrophages; viable but dormant for years; immunosuppression = activity; transmission via aerosol droplets
Work-up : acid-fast so use Ziehl-Neelsen stain; nucleic probes in DNA through PCR, cultured on Lowenstein-Jensen agar
Management : long tx: combined abx (6 mo): Isoniazid, Rifampin, Pyrazinamide, Ethambutol
Rickettsia rickettsii
*Rocky Mountain Spotted Fever (ticks)
Category : gram - unicellular
S & S : high fever, malaise, rash (palms and soles –> covering entire body); rash may convert to macular, then petechial, then hemorrhagic
Pathogenesis : transmitted to human by bite of infected wood or dog tick; killing host cell (endothelial); focal thrombi; small hemorrhages and hemodynamic disturbances
Work-up : very difficult: serologic tests based on presence of antibodies (neg in the first 7-10 days); clinical decision to treat must be based on clinical ground (hx and PE)
Management : Doxycycline
