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18 terms

skin and wound infections

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Streptococcus pyogenes, group A
Gram + cocci in chains, beta hemolytic colony, Skin infection, Impetigo, cellulitis, erysipelas; may be accompanied by Scarlet fever, Culture and biochem ID; antigenic confirm, Hyaluronic acid capsule; antiphagocytic; Erythrogenic toxin (Scarlet fever rash); Streptolysin O and S (cytotoxic), "Group A strep"
Staphylococcus aureus
Gram + cocci in clusters, yellowish beta hemolytic colony, Skalded skin syndrome (Toxic Epidermal Necrolysis under 5 yo), Exfoliatin toxins destructive to epithelial cells; localized red rash (may follow conjunctivitis or URT infection), Culture and biochem ID; antigenic confirm; need suscept test, Toxins & invasive enzymes inc. coagulase, fibrinolysin, lipase, proteases; coagulase +, Large fluid-filled bullae follow rash which burst , epidermis peels, 85% are beta-lactam resistant; 30% are MRSA and increasing
Streptococcus pyogenes, group A
Gram + cocci in chains, beta hemolytic colony, Necrotizing fascitis and Streptococcal TSS, Acute toxic and necrotic tissue invasion; rapid destruction of muscle and fat; high fever, prominent pain; life threatening, Culture and biochem ID; antigenic confirm, Hyaluronic acid capsule; antiphagocytic; Erythrogenic toxin (Scarlet fever rash); Streptolysin O and S (cytotoxic), Aggressive antimicrobic (penicillin) and surgical debridement
Enterococcus faecalis
Gram + cocci, Surgical wound infection, Frequent cause, Need susceptibility test, Multi-drug resistant strains, including vancomycin resistance (VRE)
Escherichia coli
Gram - bacilli, Infrequent; inflammation and purulent discharge; nosocomial (ex., bedsore), Routine culture and biochem ID, susceptibility test, 2 types, UTI or enterotoxic e coli
Staphylococcus epidermis
Gram + cocci, Wound/incision infection, infrequent, Coagulase -, Predominant norma flora of skin
Vibrio vulnificus
Gram - curved bacilli, Cellulitis (wound infection), Severe skin/tissue infection, hemorrhagic bullae, necrotizing fascitis; seawater contaminating a break in the skin, Infrequent (100 cases/yr of V. vulnificus); found in warm coastal seawater; fatality 15%,
Acinetobacter baumannii
Gram - bacilli, Post-traumatic wound abscess (and septicemia), Opportunistic - Afghanistan & Iraq, Vietnam; natural and nosocomial, McConkey, quick ID and suscept test, Prolonged survival on surfaces (cleanliness impt); from soil & water, Increasingly resistant; 35% susceptible to imipenem only, 4% resistant to all drugs (WRAMC 2004)
Bacteroides fragilis
Gram - bacilli, anaerobe, often pleomorphic, Deep wound abscesses, Especially when contaminated with endogenous material, Culture anaerobically; special handling (opportunistic), More from battlefield wounds (trauma),
Bacillus anthrax
Gram - bacilli, SF, cutaneous anthrax, Spores enter through cut, produces papule, then vescicle, then necrotic lesion (black scab); can lead to systemic infection, blood agar, Lethal toxin, Highly infectious; easily aerosolized; Wool-sorter's disease and biothreat agent; 95% of cases, 20% mortality; vaccine protects against toxin, Responds well to early antibiotic treatment
Herpes simplex virus
Types 1,2; DNA virus, Herpes, Fever blisters, cold sores, gingivostomatitis, keratoconjunctivitis, genital lesions, meningitis (neonate), Cell culture and immunodiagnostic, Held in check by cell-mediated immunity (CMI); first lesion most severe; hides in nerve ganglia; usually recurs from stressor, Acyclovir to relieve symptoms (goes back to latency); no vaccine
Herpes zoster virus
DNA virus, chicken pox, shingles, 1st chicken pox: vessicle-type skin lesions mostly on trunk; 2nd shingles: reemerges after hiding, small closely-spaced vessicles in area served by infected nerve, Cell culture and immunodiagnostic, Acquired via resp tract; may hide in nerve ganglia; held in check by CMI; common areas for shingles: under breast, shoulder blade, thigh, Vaccine for chicken pox available
Epstein-Barr virus (a herpes virus)
DNA virus, Infectious mononucleosis, Fever, pharyngitis, fatigue; 1-2 months, Antibody test and clinical signs, Usually asymptomatic, usually symptomacit in adolescence, young adulthood; suspected for latency, chronic diseases, Treat symptoms, no vaccine or antiviral
Norwalk virus (Norovirus)
Gastroenteritis, Vomiting and diarrhea; 18-48h incubation; transmitted by food, water, vomitus, 30-50% of epidemic (100s of people) nonbacterial gastroenteritis; usually older children and adults; schools, camps, cruise ships, etc.,
Variola major (of Orthopox family)
DNA virus, small pox, Rash to macules to vesicles to pustules to scabs; 30% mortality, Touch prep slide from vesicles or pustules; rule out Varicella-Zoster virus, Lesions on face, mouth, hands, palms, forearms, spreads to lower extremities in 7-16d
Candida albicans
yeast, cutaneious, nails, Found in axilla, groin, mammary folds, interdigital; inflammation possible (diaper rash); nails become hardened, thickened, brownish, striated, Generally none needed, KOH wet prep, culture, biochem ID, Normal flora, opportunistic, mild infections unless immunocompromised
Microsporum, Trichophyton, Epidermophyton
molds, Tinea capitis, tinea pedis, tinea corporus, Tinea capitis: "ringworm" of scalp, tinea pedis: athlete's foot, tinea corporus: jock itch, KOH wet prep, Dermatophytic molds
Sporothrix schenckii
fungus, Sporothrichosis, Skin and subcutaneous fungal infection; small, nontender, moveable, primary lesion; multiple secondary lesions along lymph channels, Primary lesion 3w after injury; may become chronic; from soil, wood, vegetation, risk to outdoor workers