Cocci

Cocci 5 pathogenic cocci/ pyogenic cocci - G+: staphylococcus S. aureus streptococcus S. pyogenes, S. pneumoniae - G-: Neisseria N. meningitidis, N. gonorrhea

(I) Staphylococcus

Staphylococcus Primary reservoir >30 species -Human carriers -Nasopharynx, throat, skin >30 species - main bacteria in the nosocomial infection - S. aureus: the most virulent species - S. epidermidis: opportunistic pathogen - S. saprophyticus: rarely cause human diseases

Thermostable nuclease Comparison Properties S. Aureus S. Epidermidis S. saprophyticus Pigment Golden yellow white citrine Coagulase + - Mannitol Thermostable nuclease Hemolysin SPA pathogenicity strong weak

Biological characteristics Grape like-clusters, no capsule Facultative anaerobes Liposoluble pigments Hemolysis Resistance

Pathogenicity (S. aureus) Virulence factors invasiveness - surface structure SPA - invasive enzymes coagulase Toxin---exotoxins - hemolysins/ Staphylolysin - leukocidin - Staphylococcal enterotoxin - toxic shock syndrome toxin-1, TSST-1 - exfoliative toxin/ epidemolytic toxin

SPA inhibits phagocytosis IgG Fc receptor PHAGOCYTE BACTERIUM Fab Fc Free protein A binds to Fc of IgG, blocking Fc receptors and is thus anti-phagocytic.

Pathogenicity (S. aureus) Disease Invasive infection/ pyogenic infection - local infection: lesion is limited in local area - organ infection: pneumonia, meningitis - systemic infection: septicemia, pyemia Bactermia (from abscess, wound, burn) , Osteomyelitis (tibia) ,Pneumonia

folliculitis Boil/ furuncle

Impetigo---staph skin infection, multiple pustules (small skin abscesses) carbuncle

Pseudomembranous Enteritis, PME Pseudomembranous Colitis

Pathogenicity (S. aureus) Disease Toxin-associated diseases - food poisoning (enterotoxin) - TSS (TSST-1) sudden high fever, shock, kidney failure, red skin rash - SSSS (exfoliative toxin) staphylococcal scalded skin syndrome - staphylococcal enterocolitis- dysbacteriosis

Staphylococcal scalded skin syndrome (SSSS) - most often occurs in infants and young children Low mortality rate Skin blister---denudation (like scald)

Laboratory diagnosis Direct examination: Gram Stain Primary media: BAP Differential Tests. Mannitol Salts Coagulase DNase Enterotoxin Antibiotic Sensitivity (plasmid, B lactamase) : penicillin /methicillin/vancomycin API STAPH Kit

Staphylococcus epidermidis coagulase negative staphylococci Staphylococcus epidermidis Major component skin flora Opportunistic infections (less common than S.aureus) urinary tract infection (UTl) septicemia wound infection Nosocomial infections bacterial endocarditis Identification Non-hemolytic (sheep blood agar) Does not ferment mannitol Coagulase-negative Staphylococcus saprophyticus urinary tract infections

(II) Streptococcus Widely exist: Diseases: -water, air, feces, human nasopharynx Diseases: -pyogenic infection - scarlet fever -streptococcal hypersensitive disease - rheumativ fever

- G+, arranged in chains (II) Streptococcus - Nutrient requirement: high *fastidious (flesh-eating bacteria) - Facultative/ obligate anaerobe - On blood agar: *different hemolysis - Catalase negative (staphylococci +)

Classificaton based on hemolytic activity - α-hemolytic strep incomplete hemolysis opportunistic pathogens - β-hemolytic strep complete hemolysis main human pathogens -γ-hemolytic strep no hemolysis no pathogenicity

Hemolysis alpha beta gamma

Classificaton Antigenic structure - polysaccharide antigens (C Ag) * group-specific antigen * 20 groups (A-H, K-V) * group A main human pathogens - surface protein antigens (M Ag) * type-specific antigen * group A>80 serotypes

Pathogenicity (Step. Group A) Virulence factors Surface structure - LTA: adhere to host cells - M- protein - Peptidoglycan

Lipoteichoic Acid and F-protein fibronectin epithelial cells

M protein IMMUNE Complement IgG M protein NON-IMMUNE peptidoglycan fibrinogen r

Pathogenicity (Step. Group A) Virulence factors Invasive enzymes - hyaluronidase (spreading factor) - streptokinase (SK) - streptodornase (SD) Toxins---exotoxins - streptolysin (hemolysin) - erythrogenic toxin Erythrogenic toxins ---pyrogenic exotoxin scarlet fever toxin - protein - serotype A, B, C - scarlet fever

streptolysins Properties Streptolysin O (SLO) Streptolysin S (SLS) O2 Oxygen-labile Oxygen-stable Antigenicity Strong (ASO test) weak Biological Destroy WBC, platelet virulence of Mφ, NC Destroy WBC virulence of many tissues Chemical Protein (MW 60 000) Polypeptide (28 aa)

Anti-SLO test (ASO test) A neutralization test between the toxin (SLO) and its specific anti-toxin (ASO) which is used to diagnose or monitor rheumatic fever caused by group A strep.

Pathogenicity (Strep. Group A) Disease 3 types of infections - pyogenic infection: skin & subcutaneous infection, impetigo, lymphangitis, septicemia - toxin-associated diseases pharyngitis--scarlet fever - hypersensitive disease acute glomerulonephritis, rheumatic fever

pyogenic infection Acute tonsillitis--- Erysipelas Abscess with surrounding cellulitis Erysipelas Acute tonsillitis--- There is a risk of developing rheumatic fever Erysipelas on the cheek

toxin-associated diseases Strawberry tongue Paly around mouth Red rash

Diseases caused by other streptococci Group B strep. - neonatal infection - adult infections: endometritis, pneumonia, meningitis, endocarditis Group C strep. - epidemic sore throat, acute glomerulonephritis Group G strep. - sore throat, cellulitis, erysipelas Group D strep. - nosocomial infection, urinary infection, biliary tract infection, peritonitis

Laboratory diagnosis Direct examination: Gram Stain Primary culture ASO Tests.

Prevention and treatment Treat the pharyngitis and tonsillitis in time Antibiotics: penicillin for the first choice

(III) Pneumococcus

Characteristics Morphology & cultivation properties - G+, arranged in pairs, bullet shape - capsule: polysaccharide - blood agar or chocolate blood agar, festidious - α-hemolysis - autolysis - bile solubility test: + *distinguish from other α-hemolytic strep. - ferment inulin

Pathogenicity Virulence factors - capsule - pneumolysin & neuraminidase - Surface protein adhesin and secretory IgA protease. - Teichoic acid and the Peptidoglycan fragment, phosphorylchorine .

Pathogenicity Main disease - pneumonia *particularly young and old *after damage to upper respiratory tract e.g. following viral infection - bacteremia - meningitis - middle ear infections (otitis media)

Laboratory diagnosis + - Differentiate S. pneumoniae from other α-hemolytic strep. - bile solubility test - optochin sensitivity test -capsule swollen reaction - animal test + -

Treatment & prevention (S. pneumoniae) Sensitive to a wide range of antimicrobial agents, but resistance is common: penicllin, erythromycin, chloramphenicol, sulphonamides, clindamycin, vancmycin Prevention polysaccharide vaccine 14 capsule types mixed vaccine

Not optochin sensitive Bile solubility test Not optochin sensitive optochin sensitive Streptex antiserum Quellung reaction using antisera capsule "fixed" visible microscopically Latex agglutination - streptococci

(IV) Neisseria Genus Neisseria > 10 species N. Meningitidis - meningitis - low prevalence but high mortality N. Gonorrhoeae - human gonorrhea - high prevalence but low mortality

Biological characteristics G-, coffee bean-shaped or kidney-shaped, in pairs Capsules and pili Fastidious Resistance: very low Polymorphonuclear cells

Biological characteristics Oxidase positive Culture: 5-10% CO2 Thayer Martin. selective chocolate agar heated blood

Pathogenesis--meningococcus Virulence factors -pili: attach to nasopharyngeal mucosa -capsule -endotoxin: damage capillary blood vessel Transmission -respiratory droplets Disease - epidemic cerebrospinal meningitis

Pathogenesis--gonococcus Virulence factors -pili -IgA, protease -outer membrane protein (OMP) -LPS Transmission -sexual contact -indirect contact (basin, towel, etc) Disease - gonorrhea

X LPS PILI Capsule N. meningitidis N. gonorrhoeae Virulence Factors Similar, but – Differences in utilization LPS LPS IgA protease Capsule PILI Opacity (OPA) proteins Outer Membrane Proteins Hemolysin IgA protease PILI Opacity (OPA) proteins Outer Membrane Proteins X NO capsule NO hemolysin

Neisseria gonorrhoeae After 2-14 days Found only in man Gonorrhea: second most common venereal disease Using the Gram stain in patient specimens, the organisms are most often observed in polymorphonuclear leukocytes Gram stain of pure culture Urethral exudate

Neisseria gonorrhoeae adults -transmission: STD (sexually tranmitted disease) -clinical dsease: genitourinary tranct infection urethritis, prostatitis, epididymitis (male) cervix inflammatin (female) infertility newborns -ophthalmia neonatorum

Neisseria gonorrhoeae Pili = key in anchorage of organisms to mucosal epithelium. Nonpiliated gonococci are avirulent OUTER MEMBRANE PROTEINS Porin proteins (Por) = prevent phagolysosome fusion & allow intracellular survival [ also called protein I] Opacity proteins (Opa) = binding of organisms to epithelium [also called protein II] Reduction-modifiable proteins (Rmp) = protection against bactericidal antibodies [ also called protein III]

Bartholin’s Duct Urethritis

Disseminated gonococcal infection (DGI). Fever, polyarthritis (or monoarticular septic arthritis), and/or dermatitis (pustules on a hemorrhagic base). Purulent conjunctivitis/Ophthalmia neonatorum Infection in newborns during vaginal delivery

Smear Antibiotic therapy polymorphonuclear cell G- cocci, many in cells Culture Antibiotic therapy lactamase-resistant cephalosporin e.g. ceftriaxone resistant strains common produce lactamases destroy penicillin

Prevention and treatment penicillin 1% silver nitrate--- ophthalmia neonatorum

Neisseria meningitidis Meningococcal meninigitis Neisseria meningitidis resides in man only usually sporadic cases mostly young children outbreaks adults crowded conditions e.g. army barracks 1-4 days Second most common meningitis pneumococcus, most common Fatal if untreated Responds well to antibiotic therapy penicillin Upper respiratory tract infection adhesion pili Bloodstream Brain

Diagnosis spinal fluid Gram negative diplococci within polymorphonuclear cells meningococcal antigens Culture Thayer Martin agar

Prevention capsule inhibit phagocytosis anti-capsular antibodies stop infection antigenic variation serogroups vaccine multiple serogroups

Pseudomonas aeruginosa

Pseudomonas aeruginosa Widely distributed in nature Frequently present in small numbers in the normal intestinal flora and on the skin Commonly present in moist environments in hospitals It is primarily a nosocomial pathogen

Typical Organisms Gram- rod Unipolar flagellum (1~3) ---- actively mobile Occurs as single bacteria, in pairs, and occasionally in short chain Capsule Pili in strains obtained from clinical specimens

Culture Grow readily on many types of culture media Smooth and round colonies Multiple colony types in one culture Fluorescent greenish color Sometimes produce a sweet or grape-like or corn taco-like odor

Culture Obligate aerobic Grow well at 37~42℃and no growth at 4℃ Produce water-soluble pigments Pyocyanin; Pyoverdin; Pyorubin; Pyomelanin Produce hemolysin Oxidase-positive Ferment glucose but not other carbohydrates

Diverse sites of infection by P aeruginosa

Who are at risk? People with cystic fibrosis Burn victims Individuals with cancer Patients requiring extensive stays in intensive care units

Control and Treatment The spread of Pseudomonas is best controlled by cleaning and disinfecting medical equipment. In burn patients, topical therapy of the burn with antimicrobial agents such as silver sulfadiazine, coupled with surgical debridement, has markedly reduced sepsis. Susceptibility testing is essential. The combination of gentamicin and carbenicillin can be very effective in patients with acute P aeruginosa infections.

Summary Concepts -Pathogenic/ pyogenic cocci -ASO test Pathogenicity of 5 pathogenic cocci