S. aureus Biofilms

Staphylococcus aureus ALL STAPHYLOCOCCI are:ALL STAPHYLOCOCCI are: 1. Gram-positive 1. Gram-positive 2. Cocci 2. Cocci 3. Clusters (Grape clusters) 3. Clusters (Grape clusters)

Levels of Infection ColonizationColonization Skin infectionsSkin infections Metastatic InfectionsMetastatic Infections ToxinosesToxinoses

Colonization AsymptomaticAsymptomatic The nares and throat of % of normal healthy adults are colonizedThe nares and throat of % of normal healthy adults are colonized Adhesins involved in colonizationAdhesins involved in colonization This can result in spread of the infection to othersThis can result in spread of the infection to others AutoinoculationAutoinoculation

S. aureus infections Skin infection. Can be caused by autoinoculation or spread from person-to-person (sometimes animal-to-person)Skin infection. Can be caused by autoinoculation or spread from person-to-person (sometimes animal-to-person) S. aureus is the most common cause of pyogenic skin infectionsS. aureus is the most common cause of pyogenic skin infections –Folliculitis –Furuncle –Carbuncle –Impetigo –Cellulitis –Necrotizing Fasciitis

Folliculitis Superficial infection of the hair follicleSuperficial infection of the hair follicle Self-limitingSelf-limiting

Furuncle Deeper-seated than folliculitisDeeper-seated than folliculitis Pyogenic - abscessPyogenic - abscess

Carbuncle Furuncles fused together

Impetigo ContagiousContagious Usually on faceUsually on face Bullous impetigo - larger bullae, may be on bodyBullous impetigo - larger bullae, may be on body

Cellulitis Cellulitis is usually associated with StreptococcusCellulitis is usually associated with Streptococcus Can accompany foot ulcers in diabetic patientsCan accompany foot ulcers in diabetic patients Deep tissue infectionDeep tissue infection Subcutaneous or submucosalSubcutaneous or submucosal

Necrotizing Fasciitis Infection of the superficial muscle fascia and adjacent subcutaneous tissue. More often caused by Group A Strep

Metastatic S. aureus infections EndocarditisEndocarditis Pneumonia (nosocomial, CF-related, post-influenza)Pneumonia (nosocomial, CF-related, post-influenza) PyomyositisPyomyositis Epidural abscessEpidural abscess Brain abscessBrain abscess OsteomyelitisOsteomyelitis

OSTEOMYELITIS Collagen binding proteinCollagen binding protein

S. aureus Toxinoses Toxic shock syndromeToxic shock syndrome Scalded skin syndromeScalded skin syndrome Food poisoningFood poisoning

Toxic Shock Syndrome Associated with tampon use in early 80’s - ignored for a while but is re-emergingAssociated with tampon use in early 80’s - ignored for a while but is re-emerging Soccer shoes in EnglandSoccer shoes in England Must be colonized with a TSST-producing strain and must lack antibodiesMust be colonized with a TSST-producing strain and must lack antibodies High fever, flushing, sloughing of skin on extremetiesHigh fever, flushing, sloughing of skin on extremeties

Staphylococcal superantigens

Scalded Skin Syndrome Usually in children and neonatesUsually in children and neonates Erythema & sunburn-like rashErythema & sunburn-like rash Desquamation due to exfoliatin toxinDesquamation due to exfoliatin toxin

Food Poisoning Food poisoning vs. food infection: staphylococcal enterotoxins (SEA, SEB etc.)Food poisoning vs. food infection: staphylococcal enterotoxins (SEA, SEB etc.) 2-6 hours between ingestion and symptoms2-6 hours between ingestion and symptoms The toxin mainly induces vomitingThe toxin mainly induces vomiting Staph is salt tolerant & can grow in foods that other bacteria can’t like hamStaph is salt tolerant & can grow in foods that other bacteria can’t like ham

Antibiotic resistance in S. aureus 1940 Penicillin 1944  -lactamase 1960 Methicillin/ Oxacillin 1970’s mecA Vancomycin 1996-VISA 2002 VanA 2000’s Daptomycin

S. aureus: The “Superbug”

S. aureus Biofilms Diabetic foot ulcer Endocarditis Catheter

Jefferson et al. AAC 49(6); 2467

55 yo wm with Type II DM had severe osteoarthritis of the rt knee for years. 03/07 underwent rt total knee replacement. PostOp course uncomplicated. Did well until 5/07 when he developed increasing pain, swelling, and erythema of rt knee joint. Aspiration of knee joint revealed frank pus. Culture grew MSSA. Patient admitted and treated with IV vancomycin (penicillin allergy). ID consulted and recommended removal of joint hardware followed by prolonged IV vanc. Patient and family decided against joint removal and opted for debridment and prolonged antibiotics. The joint was irrigated and debrided. Patient received 6 wks IV vanc with rifampin followed by 2 mos PO bactrim. Joint improved without significant pain and patient was able to ambulate patients PC stopped bactrim. 5 days later, patient presented with increasing erythema, pain and swelling of the knee joint w/ fevers. Aspiration of the joint revealed frank pus and cultures grew MSSA. He was taken to the OR and all joint hardware was removed, an antibiotic spacer was placed, and he will receive an additional 6 wks vanc and rifampin before consideration of joint replacement.

Inserted synthetic devices Polysaccharide intercellular adhesin PIA/PNAG

What controls biofilm formation in S. aureus?

NaCl EtOH Glucose External, environmental factorsExternal, environmental factors –Ethanol, NaCl, glucose Internal regulatorsInternal regulators –IcaR,  B, SarA Phase variationPhase variation –IS elements icaC icaB icaA icaR BB SarA icaR - - IcaA icaD D IcaC IcaB ? O2O2 S 

Bioinformatics Approach Different strains have different biofilm-forming capacities.Different strains have different biofilm-forming capacities. Can we predict biofilm formation based on sequence analysis?Can we predict biofilm formation based on sequence analysis?