1. Staphylococci

2. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Case Study uA 19-year-old woman complained of fever, flank pain, dysuria, urgency to urinate, and blood-tinged urine uA urinalysis revealed many white blood cells and white blood cell casts uA urine culture grew 45,000 CFU/ml of white nonhemolytic colonies on blood agar; no growth appeared on MacConkey’s agar uThe organism was catalase-positive and slide-and-tube–coagulase negative uIt produced no zone of inhibition in the presence of a novobiocin disc

3. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Points to Consider uWhat clinical manifestation does the patient present? uHow would you characterize this group of organisms? uWhat factors contribute to the virulence of this group of organisms? uWhat other factors would you consider to determine the clinical significance of this group of organisms? uOther points to consider

4. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Staphylococcus : General Characteristics  Gram-positive spherical cells (0.5- 1.5  m) in singles, pairs, and clusters uAppear as “bunches of grapes” Scanning electron micrograph of staphylococci Gram-stained smear of staphylococci from colony

5. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uNonmotile uNon–spore-forming uNonencapsulated uCatalase-producing Staphylococcus : General Characteristics

6. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uApproximately 33 species u14 to 17 species associated with humans uSeveral veterinary pathogens uSpecies initially differentiated by the coagulase test Genus Staphylococcus

7. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uS. aureus uS. intermedius uS. hyicus uS. delphini uS. schleiferi Veterinary pathogens Animal-associated species Human pathogen Coagulase-Positive Staphylococci

8. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uS. capitis uS. caprae uS. sciuri uS. hominis uS. schlieferi uS. cohnii uS. xylosus uS.epidermidis uS. saprophyticus uS. haemolyticus uS. lugdunensis uS. kloosii uS. saccharolyticus uS. simulans Coagulase-Negative Staphylococci

9. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uHabitat: anterior nares (carriers) uPrimary pathogen of the genus uProduce superficial to systemic infections uMode of transmission: traumatic introduction uPredisposing conditions 4Chronic infections 4Indwelling devices 4Skin injuries 4Immune response defects Clinically Significant Staphylococci: Staphytoccus aureus

10. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Virulence Factors: Extracellular Enzymes uHemolysins: hemolyze RBCs 4Alpha: platelets/WBCs/tissue 4Beta (hot/cold): sphingomyelin of RBCs 4Gamma: host cell membranes 4Delta: less lethal uLeukocidin (Panton-Valentine): kill PMNs uEnterotoxins 4A/D: food poisoning 4F: TSSAT 4B: pseudomembranous enterocolitis

11. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Virulence Factors: Extracellular Enzymes uExfoliatin 4Epidermolytic toxin 4Phage group II staphylococci 4SSS or Ritters Disease uTSST-1: Toxic shock syndrome toxin-1 4Multisystem disease 4High fever 4Hypotension 4Shock

12. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Virulence Factors: Extracellular Enzymes uHyaluronidase: connective tissue uStaphylokinase: fibrinolysin uCoagulase: virulence marker uLipase: allows colonization uPenicillinase: confers resistance

13. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uSkin and wound 4Impetigo 4Furuncles 4Carbuncles 4Boils 4Surgical wound infections uFood poisoning uScalded skin syndrome Bullous impetigo Staphylococcus aureus: Clinical Infections

14. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uToxic shock syndrome uOther infections 4Respiratory (less often) 4Bacteremia 4Osteomyelitis Staphylococcus aureus: Clinical Infections

15. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Coagulase-Negative Staphylococci uHabitat: skin and mucous membranes uApproximately 33 species uCommon human isolates 4S. epidermidis 4S. saprophyticus 4S. haemolyticus

16. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Coagulase-Negative Staphylococci: Staphylococcus epidermidis uHabitat: skin and mucous membranes uCell wall: glycerol-teichoic acids uVirulence factor: “slime” uMode of transmission: implantation of medical devices such as catheters, shunts, and prosthetic devices uInfections are acquired nosocomially uSerious infections among immunosuppressed patients may occur

17. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uHabitat: skin and mucosal membranes of the genitourinary tract uCommon cause of urinary tract infections in young, sexually active females uWhen present in urine cultures, may be found in low numbers, but significant Coagulase-Negative Staphylococci: Staphylococcus saprophyticus

18. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Other Gram-Positive Cocci uHabitat: skin and mucous membranes uRarely implicated in infections uS. haemolyticus associated with wound infections, bacteremia, and endocarditis uS. lugdunensis and S. schleiferi are also found to be opportunists

19. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Laboratory Diagnosis: Specimen Collection and Handling uSamples must be taken from the actual site of infection uPrevent delay in transport of collected material from infected sites uTransport in appropriate collection device that would prevent drying and minimize growth of contaminating organisms

20. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Microscopic Examination 4Gram-positive cocci 4pairs and clusters 4Numerous polymorphonuclear cells (PMNs) Insert Figure 10-1 Laboratory Diagnosis: Direct Smear Examination

21. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Laboratory Diagnosis: Cultural Characteristics uColony morphology 4Smooth, butyrous, white to yellow, creamy 4S. aureus may produce hemolysis on blood agar S. aureus

22. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Laboratory Diagnosis: Cultural Characteristics uCoagulase-negative staphylococci 4Smooth, creamy, white 4Small-to medium- sized, usually non-hemolytic uS. saprophyticus 4Smooth, creamy, may produce a yellow pigment

23. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uPrinciple: tests for enzyme catalase 2 H 2 O 2 2 H 2 O + O 2 uDrop H 2 O 2 onto smear uBubbling = POS (Most bacteria, O 2 generated) uNo bubbling = NEG (Streptococci and other lactic acid bacteria, no O 2 generated) Identification Tests: Catalase

24. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uDetects enzyme coagulase 4Cell-bound “clumping factor” 4Extracellular enzyme “free coagulase” uTwo methods 4 Slide test 4Tube test Slide coagulase test detects clumping factor Identification Tests: Coagulase Test

25. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Tube test detects the extracellular enzyme “free coagulase” Identification Tests: Coagulase Test

26. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Novobiocin Susceptibility Test uTest to differentiate coagulase- negative staphylococci from S.saprophyticus from urine samples 4S. saprophyticus is resistant (top) 4Other CNS are susceptible

27. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Schematic Diagram for Identifying Staphylococcal Species

28. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. uFor non–beta-lactamase producing S. aureus (methicillin- susceptible) 4Penicillinase-resistant synthetic penicillins (methicillin, nafcillin, oxacillin, dicloxacillin) uFor methicillin -resistant S. aureus (MRSA) and methicillin- resistant S. epidermidis (MRSE) 4Vancomycin combined with rifampin or gentamicin uEmergence of vancomycin resistance Antimicrobial Susceptibility

29. W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company. Points to Remember uGeneral characteristics of staphylococcal species uInfections produced by pathogenic species uMicroscopic and colony morphology uTests used to identify these species uEmergence of resistant strains