Bacterial Skin infections I Flashcards
Streptococcus pyogenes General
- Causes Decubitus ulcers,Pressure/Bed Sore
- Gram positive cocci, chains, Catalase negative,M & T proteins, Group A
Streptococcus pyogenes Virulence factors
-Exotoxin, Streptolysins/Streptokinase, Deoxyribonuclease, Hyaluronidase
-antiphagocytic capsule,adherence,M‐protein
• immune system evasion (SEP B)
Streptococcus pyogenes Clinical Manifestations
-Impetigo, Pharyngitis, ERYSIPELAS, Cellulitis, Necrotizing fasciitis, SCARLET FEVER
Staph Epidermis found on what items
Prosthetic devices, catheters
Staph Epidermis Pathogenesis
Slime production, Biofilm,
Pseudomonas aeruginosa General
-skin and BURN infections
-Gram‐negative rod, Motile, Oxidase positive, nosocomial, strict aerobe, nonfermenting, aquatic environments,lactose negative
• fruity aroma
• Multi‐drug resistance
-Green pigment
Pseudomonas aeruginosa Transmission/epidemiology
-soil, water, food, on plants
–survives many disinfectants
• Transmission: invasive device (Foley catheter), destruction of protective structure (ie. skin)
Pseudomonas aeruginosa Virulence factors
biofilm (alginate), quorum sensing, enzymes & toxins, degradative enzymes,type III secretion system, proteases, hemolysins
Enterobacteriaceae General
Gram neg rod, normal gut flora, rarely cause cellulitis
Haemophilus influenzae General
Gram negative rods/coccobacilli, X and V factor –
• Disease Associations: Meningitis,Osteomyelitis,Epiglottitis,Otitis media, RARE CAUSE OF CELLULITIS
What bacteria causes Decubitus ulcers Pressure/Bed Sore
-MIXED FLORA • Pseudomonas • Staphylococcus sp. • Streptococcus sp. • Corynebacterium sp.
Causes of Chronic Ulcers
Mycobacterium tuberculosis • M. fortuitum complex • M. marinum • M. ulcerans • M. leprae • Nocardia brasiliensis • Corynebacterium diphtheriae
Mycobacterium General
Gram positive cell wall, Acid fast, Slow growth
Mycobacterium fortuitum complex -what type of people
Injecting drug users
Mycobacterium MARINUM-where contracted
swimming pool granuloma
– “aquarium or fish tank
Mycobacteria
Mycobacterium leprae General
-obligate intracellular: peripheral nerves,skin, nasal mucosa
-slow incubation period:3–5 years
-no in vitro growth: mouse foot pads,
armadillos
Mycobacterium leprae Virulence factors
-cell wall, mycolic acids & wax D, acid fast positive
-obligate intracellular
–inhibition of phagosome‐lysosome fusion
– drug resistance
Mycobacterium leprae Diagnosis
PCR, clinical, NO CULTURE
Mycobacterium leprae Clinical manifestations
HANSENS DISEASE-tuberculoid, lepromatous
Nocardia brasiliensis General
branching, intracellular, opportunist, partial acid‐fast, beaded Gram (+) bacilli
Nocardia brasiliensis Clinical Manifestations
Chronic ulcer
Corynebacterium diphtheriae General
pleomorphic Gram (+) bacilli -cutaneous diptheria: – unimmunized population – over‐crowding conditions • chronic ulcer
Corynebacterium diphtheriae Virulence
• diphtheria toxin – inhibits protein synthesis • cutaneous diphtheria – rare – unimmunized population – over‐crowding conditions
Propionibacterium acnes General
Gram (+) bacilli (related to Corynebacterium)
• slow‐growing, non‐spore forming, anaerobic
• produce lactic acid, propionic acid, acetic acid
from glucose
• Normal skin flora
Propionibacterium acnes Clinical Manifestations
-mostly on face, upper thorax
• cause acne
– produces inflammatory mediators resulting in papules, pustules, lesions typical of inflammatory acne
– usually self‐limiting
Diabetic foot Infection caused by what bacteria?
Polymicrobial:
– S. aureus
– Enterococcus sp.
– Enterobacteriaceae
– Group B Streptococci
-Streptococcus agalactiae
– anaerobic bacilliFasciitis caused by what bacteria?
- Clostridium perfringens
- S. pyogenes
