Staphylococcus Eva L Dizon M D FPPS FPIDSP

Staphylococcus Eva L. Dizon, M. D. , FPPS, FPIDSP

Staphylococcus Staphyle- Bunch of grapes 0. 5 to 1 um Non motile Aerobic or Facultative Anaerobic Catalase positive Grow in media containing 10% Na. Cl at temp 18 to 40 C Present on the skin and mucuos membrane

Species S. aureus S. epidermidis S. saphrophyticus S. capitis S. haemolyticus Micrococcus sp Stomatococcus mucilaginosus Alloiococcus otitidis

Physiology and Structure

Structure

Structure CAPSULE- loose fitting polysaccharide layer (slime layer) - protects bacteria by inhibiting and phagocytosis chemotaxis - facilitates adherence of bacteria to catheters and synthetic materials PEPTIDOGLYCAN- half of the cell wall - consist of layers of glycan chains with alternating subunits of N –acetylmuramic acid and N- acetylglucosamine - has endotoxin like activity

Structure TEICHOIC ACID- phosphate containing polymers bound to peptidoglycan layer or to cytplasmic membrane S. aureus - mediates the attachment of. Ribitolstaphylococcus teichoic acid with N-acetylglucosamine to mucosal surfaces ( Polysaccharide A) S. epidermidis glycerol teichoic acid with glucosyl residues (polysaccharide B)-

PROTEIN A- covalentlylinked to peptidoglycan - has affinity to Fc receptor of Ig - blocks opsonization and phagocytosis

Structure COAGULASE and other SURFACE PROTEIN -Clumping factor or Bound coagulase binds fibrinogen convert to insoluble fibrin causing staphylococcus to clump - collagen , elastin and fibronectin binding protein CYTOPLASMIC MEMBRANE- osmotic barrier for the cell and provides an anchorage for the biosynthetic and respiratory enzyme

Toxins A. 5 Cytolytic or membrane damage toxin 1. Alpha 2. Beta 3. Gamma 4. Delta 5. Panton Valentine B. 2 Exfoliative toxin C. 8 Enterotoxin D. Toxic Shock Syndrome Toxin(TSST 1)

Cytotoxins Lyse neutrophils release of lysosomal enzymes damage sorrounding tissues Alpha toxin – disrupts the smooth muscle in blood vessels - toxic to erythrocytes, hepatocytes, platelets, cultivated cells - integrates to host cell membrane pores efflux of K and influx of Na, Ca osmotic swelling cell lysis - septic shock

Cytotoxin Beta Toxin - Sphingomyelinase C - specific for sphingomyelin and lysophosphatidylcholine - toxic to RBC, WBC, Macrophage and fibroblast - catalyze hydrolysis of membrane phospholipids in susceptible cells - tissue destruction and abscess formation Delta toxin- disrupts cell membrane - toxic to variety of cells

Cytotoxin Gamma toxin and Panton Valentine -both damage membrane of susceptible cells - lyze nuetrophils and macrophages - cell lysis is mediated by pore formation -Cause necrotizing skin infection --PVL -potent leukotoxicity

Exfoliative toxin ETA - heat stable ETB – heat labile Serine protease Exposure splitting of desmosomes or intercellular bridges in the stratum granulosum epidermis Common in neonates – ETA and ETB binds to GM 4 like glycolipids present in neonates

Enterotoxin A-E, G-I Stable to heating , resistant to hydrolysis Enterotoxin A – most commonly associated with disease Enterotoxin C and D- contaminated milk products Enterotoxin B- Pseudomembranous colitis Superantigens

TSST-1 Formerly pyrogenic exotoxin C and entertoxin F Induce cytokine release from macrophage and T lymphocytes Increase sensitivity to endotoxin Produce leakage of endothelial cells Penetrate mucosal barrier

Staphylococcal enzymes Coagulase Bound convert fibrinogen insoluble fibrin Free react with globulin plasma factor to form staphylothrombin Clumping Cause formation of fibrin layer around abscess protecting staphylococcus from phagocytosis

Staphylococcal enzymes Catalase- catalyze the conversion of toxic hydrogen peroxide to water and oxygen Hyalurodinase- hydrolyzes hyaluronic acid in acellular matrix of connective tissue spread

Staphylococcal enzymes Fibrinolysin- staphylokinase. Dissolve fibrin clot- aid in bacterial spreading Lipases hydrolyse lipid to ensure survival in sebaceous areas of the body Nuclease Penicillinase- plasmid Fatty acid modifying enzyme (FAME)antibacterial lipid- prolonged bacterial survival

Epidemiology Transient colonizer of skin Nasal carriage – anterior nasopharynx Persistent carrier – hospital personnel Killed by high temperature and disinfectant Direct contact, fomites Handwashing

Sites of infection

Ritters disease or SSSS Perioral erythema spread body bullous desquamation Nikolsky sign Bullous impetigo – localized form of SSSS - localized blister - culture positive

SSSS most commonly in children and neonates. Starts abruptly with perioral (around the mouth) erythema with sunburn-like rash rapidly turning bright red spreading to bullae (large vesicle appearing as a circumscribed area) in 2 -3 days and desquamating (peeling) within 5 days.

Staphylococcal food poisoning Ham , salted pork, custard, potato sald, ice cream Hands, Nasal carriage I. P. – 4 hrs Vomiting, diarrhea, abd. pain

Toxic shock syndrome Growth of organism in vagina or wound release of TSST-1 Fever, macular erythematous rashes, hypotension, multiorgan involvement, desquamation of palm and sole

TSS

Cutaneous infection Impetigo Folliculitis Furuncle Carbuncle Wound infection

Folliculitis - superficial folliculitis is essentially a staphylococcal impetigo in which a small area of erythema develops around a hair follicle and subsequently becomes a dome-shaped pustule. Carbuncle - a deep-seated pyogenic infection of the skin and subcutaneous tissues.

Impetigo - a contagious superficial pyoderma, caused by S. aureus and Streptococcus pyogenes, that begins with a superficial flaccid vesicle which ruptures and forms a thick yellowish crust, most commonly occurring in the face.

Others Bacteremia Endocarditis Pneumonia Empyema Osteomyelitis Septic arthritis

Pneumonia

S. Epidermidis and CNS Endocarditis- native or artificial valves Catheter and shunt infection Prosthetic joint infection UTI

Laboratory diagnosis Microscopy Culture Grow rapidly within 24 hours Large, golden, smooth colonies Blood Agar- hemolysis Selective media- add Na. Cl 7. 5% Mannitol – fermented by S. aureus Serology Insensitive Antibody against teichoic acid Bacteremia. Endocarditis After 2 weeks

Culture – S. aureus

S. epidermidis S. saphrophyticus

Coagulase test Showing positive (upper tube) and negative (lower tube) coagulase tests.

Mannitol Salt Agar test

Identification Biochemical testing Coagulase Heat stable nuclease Alkaline phospatase Mannitol fermentation test

Treatment and Prevention Semisynthetic penicillinase resistant penicillin Resistance ( mecgene A –codes for PBP 2’)

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