Causative agents of inflammatory suppurative and septical infections

Causative agents of inflammatory, suppurative and septical infections DEPARTMENT OF MICROBIOLOGY AND VIROLOGY PIROGOV’S RSMU

Aerobic and facultative anaerobic bacteria (the main species) Staphylococci • Streptococci • • • • • Pseudomonas Proteus Klebsiella Staphylococcus aureus S. epidermidis S. saprophyticus Streptococcus pyogenes S. faecalis (enterococcus) S. . sanguis, S. . mutans, S. mitis P. aeruginosa P. vulgaris K. pneumoniae K. ozenae

Staphylococci • Famaly Micrococcaceae • Genus Staphylococсus • Species > 30 Coagulasa+ S. aureus, S. intermedius Coagulasa - S. epidermidis, S. saprophyticus, S. hominis, S. capitis, S. warneri, S. haemolyticus

Staphylococci • Staphylococcus aureus The name aureus means “golden" refers to bronze pigmentation of colonies (other are white). • S. saprophyticus is unique in that it apparently causes only urinary tract infections. • In Gram stain Staphylococcus look like clusters of grapes (staphylo from Greek word for grape clusters)

Staphylococcus aureus

S. epidermidis

S. aureus S. epidermidis

Disease caused by Staphylococci • • • Skin and soft tissue infection Furuncles Wound infections (traumatic, surgical) Endocarditis Cellulites Brain abscess Central nervous system infections Osteomyelitis Arthritis Musculoskeletal infection

Pus-producing

Staphylococcus-infections

Factors of Pathogenicity • • • Toxin-related disease Toxin shock syndrome (TSS) Scalded skin syndrome (SSS) Food poisoning (gastroenteritis) Perinatal infections of the mother and your babi Neonatal infections (sepsis) Factors: Leukocidin Hemolisins Enterotoxin Exfoliatin Enzymes • Coagulase Hyaluronidasa Catalase • -lactomase Lecithinase Phosphatase

Catalase Bubbing upon the addition of hydrogen peroxide is indicative of the presens of catalase for this organisms

Staphylococcus hemolysins (blood agar)

Superantigens TSS-toxin and Enterotoxin

The diagnostic tests • Morphology: cluster of large Gram-positiv cocci. A few strains possess microscopiccally visible capsules. • Bacteriology: culturing a specimen of pas on agg yolk with salt. • Biochemical testing: Staphylococci ferment a number sugars, producing acid but no gas • VPT+, indol-negativ, liquefy gelatin • Serological test: the reaction of toxin-neutralisation

Treatment • Staphylococci are resistent to penicillin • Semisynthetic penicillins and cephalosporins are resistant to -lactomase and may be useful. Methicillin - with this property • However, methicillin-resistance has shreed to all hospitals and ofen requeresthe use of • vancomycin • cyprofloxacin, • rifampicin

Prevention • Antiserum (immune globulin) • Vaccine (toxoid) • Anti-staphylococcal bacteriophage

Streptococci

Streptococci • Streptococci are Gram-positive cocci arranged in chains or pairs

The classification • I. Streptococci are divided by the type of hemolysis: • Alpha- hemolytic produce a greenish discoloration with partial hemolysis (S. pneumoniae, viridans-group) • Beta- hemolytic produce a sharply defined clear, colourless zone (S. agalactiae) • Gamma or nonhemolytic streptococci (S. fecalis – Enterococci)

S. pyogenes blood agar

Classification Lancefield groups • Streptococci may be grouped serologically according to their major cell-wall carbohydrate antigens ( groups A - T) • A. - Streptococcus pyogenes B. - Streptococcus agalactiae D. H. - S. faecium, S. fecalis (Enterococci) C. - Streptococcus equisimilis - S. sanguis K. - S. salivaris • Viridans group: S. mitis, S. mutans

Streptococcus pyogenes

S. faecalis

Disease caused by streptococci • Group A S. pyogenus causes upper respiratory tract infections, “strep throat”, scarlet fever, rheumatic fever, pyoderma • Group B S. agalactiae causes neonatal sepsis • Group C and G cause abscess • Group D causes bacterial endocarditis and dental caries

Group A streptococci

Group B

Factors of pathogenicity • M. protein (acts by ingibiting phagocytosis) • Hemolysins: streptolysin “O”(oxygen labile) and “S” (stable) Erithrogenic (scarlating) toxin • • Streptokinase (fibrinolysin) • Streptodornase causes depolymerisation of DNA • Hyaluronidase • Proteinase

Scarlet toxin

Abscess

Streptococcus pneumoniae

S. pneumoniae

Pleuritis S. pneumoniae

rheumfev

Impetigo

Keratit

Erysipelas

Scarlet (S. pyogenes)

Pseudomonas aeruginosa • P. aeruginosa is ubiquitous opportunistic pathogen (in soil, water) • P. aeruginosa produced a number of pigments the best known being pyocyanin. • The infections caused by P. aeruginosa: • osteomyelitis, burn wound infection, • urinary tract infection (predisposing factor – kidney stones), • septicemia, pneumoniae, • meningitis (neurosurgical operations)

Pseudomonas aeruginosa

Factors of Pathogenicity • Pili (adherence, colonisation) • Flagellum (motility) • Endotoxin (stimulates vasoactive peptides, activates clotting) • Exotoxin A – histo- or cytotoxin (tissue damage, shock) • Elastase (cleavage of elastin, collagen, Ig) • Phospholipase C (tissue damage)

The diagnostic tests • Morphology: they are Gram-negative rods • Diagnosis by cultere: P. aeruginosa is obligate aerobe, grows well on ordinary media, producing colonies with bluish green pigment • Biochemical testing: catalase+, oxidase+, indol-, H 2 S-

Pseudomonas aeruginosa

Proteus swarms on solid culture media (bismuth sulphite agar. Colinies spreed on the surface of the plate to form a thin filmy layer