streptococci. general character gram positive cocci arranged in chains catalase test negative...
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General character
Gram positive cocci arranged in chains Catalase test negative Fastidious Facultative anaerobes Penicillin sensitive (Streptococcus faecalis ) Resistant to AG (GENTAMICIN )
Most important pathogen Distinguished by bacitracin test (sensitive) Some are capsulated (hyaluronic acid)
epidemiology
Acquired through infected respiratory droplet Direct contact _ Skin , hand Indirect contact _contaminated objects Spread enhanced by poverty
overcrowding
poor ventilation
Source of infection
A - Patient with active disease – tonsillitis Convalescent carriers – throat
B - Asymptomatic carriers (20% -school children ) – throat
Prevalent in children – 3 – 8 yrs
VIRULENCE FACTORES
A- CELL ASSOCIATED
1- M protein (antiphagocytic) -
originates from cytoplasmic membrane
produces protective type specific abs
2- lipoteichoic acid adhesion factor for attachment
3- hyaluronic acid capsule - antiphagocytic
3- STREPTOKINASE (fibrinolysin) Thrombotic disease – coronary thrombosis
4- DNAases A , B , C , D. AntiDNAase B - DIAGNOSE SKIN infections
5- HYALURONIDASE – spread factor
6- LIPOPROTEINASE – opacity factor
B- EXTRACELLULAR PRODUCTS1- SREPTOLYSINS OR HAEMOLYSIN
Streptolysin o antigenic , ASO , oxygen labile
Streptolysin s oxygen stable, non antigenic
2- Erythrogenic toxin (SPE )SUPERANTIGENBacteriophage – 3 types , A – B- C .SCARLET FEVER
B- EXTRACELLULAR PRODUCTS
DISEASESA - SAPURATIVE
A- SAPURATIVE 1- TONSILITIS / PHARINGITIS2- PERITONSILAR ABSCESS(QUINSY)3- OTITIS MEDIA4- ADENITIS5- IMPETIGO (PYODERMA)6- SCARLET FEVER7- CELLULITIS8- PUERPERAL SEPSIS9- INVASIVE SOFT TISSUE INFECTIOS
NECROTISING FASCITIS , MYOSITIS , TSS10 - BACTERIMIA
B- NON- SUPPURATIVE (DELAYED SEQUELAE)
1- RHEUMATIC FEVER :
autoimmune disease
follows throat infection only
recur (M – SEROTYPES)
2- ACUTE GLOMERULONEPHRITIS
Ag – Ab complexes
May follow both throat or skin infection
NO recurrence
B-NON SUPPURATIVE (DELAED SEQUELAE)
CULTURE - IDENTIFICATION
BLOOD-AGAR (AEROBIC- ANAEROBIC) BETA- HAEMOLYSIS (COMPLETE ) ID
– BACITRACIN SENSITIVITY– LANCEFIELDS GROUPING (CELL WALL CHO-
Ag)– STREPTEX
SEROLOGY
ASO-TITRE– RHEUMATIC FEVER– ACUTE GLOMERULONEPHRITIS
Anti-DNAase B– RECENT GROUP -A INFECTIONS (SKIN)
GROUP C AND G STREPT.
SORE THROAT SKIN INFECTION WOUND INFECTION SOFT – TISSUE GENITAL – INFECTION CELLULITIS SEPTICAEMIA
GROUP-B STREPTOCOCCUS(SREPT. AGALACTIAE)
RESERVOIR- COLON (RECTUM) 10-40 % FEMALE . CARRIER (VAGINA) 70% - NEOBORN – COLONISED DURING
BIRTH < 1% GET INVIASIVE INFECTION
DISEASES
A – EARLY ONSET (24 – 48 h )
RISK – FACTORS
RUPTURED MEMBRANES (>18h
PREMATURITY
PROM (< 37 WEEKS)
MULTIPLE BIRTH (TWINS)
LOW BIRTH WEIGHT
B- LATE – ONSET
HOSPITAL- AQUIRED (NOSOCOMIAL)
MENNGITIS IN FULL – TERM NEONAT.
BETTER PROGNOSIS
MORTALITY
INFECTIONS IN ADULTS
POST-PARTUM SEPSIS CHORIOAMNIONITIS IMMUNOCOMPROMISED
– SEPSIS– CELLULITIS– ARTHRITIS– PNEUMONIA
TREATMENTPREVENTION
PENICILLIN OR AMPICILLIN + GENTAMICIN SCREEN- PREGNANT W. (35-37 W) CARRIER – PROPHYLAXIES
– IV- PENICILLIN – AT LABOUR
GROUP – D STREPT.NORMAL INTESTINAL FLORA
A- ENTEROCOCCIGROW IN 40% BILE-ACID,6.5% NACLPENICILLIN RESISTENTAMPICILLIN SENSITIVE- E. FAECALIS : 80% - 90% INFECTI.- E. FAECIUM : MANY AMPICILLIN R.
B- NON-ENTEROCOCCIPENICILLIN SENSETIVESTREPT . BOVIS
DISEASES
URINARY TRACT INFECTIONS ENDOCARDITIS WOUND INFECTIONS
TREATMENT
AMPICILLIN + GENTAMICIN
VANCOMYCIN ( VRE )
S.PNEUMONIAE
PNEUMONIABACTEREMIAMENINGITISSEPTIC
ARTHRITISPERITONITIS
OTITIS MEDIASINUSITISCONJUNCTIVITIS
BRONCITIS
GRAM POSITIVE DIPLOCOCCI
POLYSACCHARIDE CAPSULES (85) ANTIPHAGOSITIC OPSONIZING ANTIBODIES ANTCAPSULAR AB. ARE PROTECTIVE PNEUMOLYSIN
RISK FACTORS
CEREBRAL IMPAIRMENT VIRAL INFECTION OLD AGE HEART FAILURE SPLENECTOMY SCA , MULTIPLE MYLOMA , HIV SKULL FRACTURE
DIAGNOSISSPUTUM , BLOOD , CSF
MICROSCOPY QUELLUNG REACTION BILE SOLUBLE OPTOCHIN SENSETIVE BLOOD CULTURE + IN 15% LATEX AGGLUTINATION SENSETIVITY TEST