Download presentation
Presentation is loading. Please wait.
Published byFrancine Gaines Modified over 9 years ago
3
Penetration of the skin by micro-organisms is difficult—Part of the innate defense Wounds provide the most common access through the skin. Disease production in infected wounds depends on › How virulent infecting organisms are › How many organisms infect the wound › Is the host immunocompetent › Nature of the wound Does it contain crushed material or foreign material
4
Leading cause of wound infections Symptoms › Bacteria are pyogenic › Infection causes Inflammation Fever › Some strains produce toxic shock syndrome More than 30 recognized strains
5
Causative Agent: S. aureus Virulence due to the production of extracellular products Coagulase Causes blood clotting to evade phagocytosis Clumping factor Aids in bacterial wound colonization Protein A Hide bacteria from phagocytic cells toxin Produces hole in host cell membrane
6
Treatment › Many strains develop resistance to antibiotics Many strains treated with anti β lactamase penicillins and vancomycin Vancomycin resistant strain identified in 1997 Epidemiology 30% to 100% due to patient’s own flora › Factors associated with infection include Advanced age Immunosupression or poor general health Prolonged postoperative hospital stay
7
Primary pathogen is S. pyogenes › Also known as “flesh eaters” Β hemolytic, Gram-positive cocci in chains › Can cause rapidly deteriorating disease and death Common cause of wound infections › Not a lot of antimicrobial resistance: early penicillin Two extracellular products are responsible for virulence Pyrogenic exotoxin A superantigen : toxic shock Exotoxin B necrotizing fasciitis
8
P. aeruginosa Major cause of nosocomial infections › Lung infections › Burn infections Community acquired infections include › Rash and external ear infections › Infection of foot bones › Eye infections › Heart valve infections › Lung biofilms
9
Pathogenesis › Some strains produce enzymes and toxins to enhance virulence Exoenzyme S Toxin A Phosphlipase C Epidemiology › P. aeruginosa is widespread in nature Prevention and Treatment › Prevention involves elimination of sources of bacteria › P. aeruginosa is multi-drug resistant › Medications must be administered intravenously at high doses
10
Symptoms › Divided into early and late symptoms › Early symptoms Restlessness Irritability Difficulty swallowing Contraction of jaw muscles Convulsions Particularly in children › Later symptoms Increased muscle involvement Pain Difficulty breathing Death
11
Causative Agent › Clostridium tetini Anaerobic Gram-negative Bacillus Spore former 25% mortality rate; rare in the developed world › tetanospasmin toxin blocks inhibition of motor neurons, causing paralysis Prevention: vaccination, treatment: antitoxin Bacterial spores prevalent in dirt and dust and gastro intestinal tract of humans and other animals
12
Causative Agent › Several species of Clostridium Most common offender, C. perfrigens Encapsulated, Gram-negative bacillus Endospores of causative bacillus are innumerable › Spores found in nearly all soil or dusty surface › Normal flora of intestinal tract and vagina Primarily disease of wartime › Due to neglected wounds containing debris › Treat with hyperbaric oxygen, antibiotics (penicillin)
13
Causative Agent › Actinomyces israelii Filamentous, anaerobic, slow growing Pathogenesis › A. israelii cannot penetrate healthy mucosa › Infection is characterized by cycles Abscess formation → scarring → formation of sinus tracts › Disease progresses to skin and can penetrate bone or central nervous system Epidemiology › Can be normal flora Prevention and Treatment › No proven prevention › Responds to numerous antibacterials Penicillin and tetracycline
14
Causative Agent › Pasteurella multocida Gram-negative Coccobacillus Rounder bacillus shape Most are encapsulated Bite infections from numerous animals › Fowl Cholera, animal reservoir Symptoms › Spreading redness › Tenderness › Swelling of adjacent tissues › Pus discharge
15
Causative Agent › Bartonella henselae Gram-negative bacillus Symptoms › Disease begins within a week › Painful enlargement of lymph nodes › Fever Epidemiology › Zoonotic disease Cats infected by flea bite › Infections treated with amipicillin
16
Causative Agent › Streptobacillus moniliformis Gram-negative,Bacillus Symptoms › Bite wound usually heals without complication › Development of chills, fever, head and muscle ache and vomiting 2 to 10 days after healing Majority of cases are self limiting 7% - 10% of untreated cases are fatal
17
Causative Agent › Sporothrix schenckii Dimorphic fungus Lives in soil and on vegetation Associated with puncture wound from vegetation Sporadic: › rare in healthy people › Untreated cases may become chronic › Itroconazole and amphotericin B
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.