Streptococcus PDF

BROKENSHIRE COLLEGE, INC BACTERIOLOGY MEDICAL LABORATORY SCIENCE STREPTOCOCCUS STREPTOCOCCI...

BROKENSHIRE COLLEGE, INC BACTERIOLOGY MEDICAL LABORATORY SCIENCE STREPTOCOCCUS STREPTOCOCCI  Normal flora of human intestine  Species: E. faecalis  Gram (+) spherical cells, arranged in chains or pairs 4) LACTIC GROUP  Grayish pinpoint translucent to  Will grow on 10°C slightly opaque colonies  Non hemolytic organism  Catalase (-), oxidase (-)  Often found in dairy products  Growth is enhanced by blood,  Species: S. lactis serum or glucose incorporated in agar plate B. SMITH AND BROWN’S CLASSIFICATION  Behave-like facultative  BASED ON HEMOLYTIC PATTERN anaerobe, some species  CLASSIFICATION OF STREPTOCOCCI require increased CO2 for growth 1) ALPHA-HEMOLYTIC STREPTOCOCCI  Aerotolerant anaerobe  Partial/incomplete hemolysis (peptostreptococci) – obligate of RBC around colony anaerobe  Green discoloration around colony  ALL streptococci EXCEPT the viridans group have a  Species: S. pneumoniae (green layer of C carbohydrate – serological classification streptococci)  Young cultures are characterized by the presence of capsule 2) BETA-HEMOLYTIC STREPTOCOCCI  Are commonly found as part of normal human flora.  Complete hemolysis of RBCs around the colony  However, when these organism gain access to  Clear area/zone around normally sterile sites they can cause life threatening colony infection.  Yellow discoloration  S. pyogenes and S. pneumoniae - notorious  Species: S. pyogenes, S. pathogens agalactiae  Aerococcus, Lactobacillus, Leuconostoc and Pediococcus – resemble streptococci 3) GAMMA-HEMOLYTIC STREPTOCOCCI  NO lysis of RBCs around  Colony variation colony/red cells immediately a) Mucoid  surrounding the colony are b) Matte or rough – large amount of CHON unaffected (no change) c) Smooth/glossy – little amount of CHON  Species: E. faecalis (GROUP D) A. ACADEMIC/BERGEY’S CLASSIFICATION C. LANCEFIELD  BASED ON TEMPERATURE  BASED ON THE ANTIGENIC NATURE OF CELL WALL  CLASSIFICATION OF STREPTOCOCCI  CARBOHYDRATES – C POLYSACCHARIDE  Rebecca Lancefield – found out that C carbohydrate 1) PYOGENIC GROUP can be extracted from the streptococcal cell wall by  Will not grow neither on 10°C or 45°C placing the organism in dilute acid and heating for 10  Produce pus; mostly β-hemolytic min.  Species: Streptococcus pyogenes  CLASSIFICATION OF STREPTOCOCCI 2) VIRIDANS GROUP  Will grow at 45°C  NOT part of the lancefield group  Alpha hemolytic OR Non hemolytic  Species: S. salivarius, S. mutans, S. mitis, S.  Sanguis 3) ENTEROCOCCUS  Will grow both at 10°C and 45°C BAUTISTA 3C  GROUP A STREPTOCOCCI INFECTIONS AND DISEASES  Pathogenic to man 1) PHARYNGITIS OR TONSILITTIS – “STREP THROAT”  Not considered part of the normal flora  Acquired thru contaminated droplets by cough or sneeze  Species: S. pyogenes – “fever producing bacteria,” flesh eating bacteria (involves deeper tissues and organs)  Principal virulence factor: M-protein (type specific; 2) SCARLETT FEVER (SCARLATINA) anti-phagocytic)  Results from a throat infection with a strain of S.  Other virulence factor: pyogenes that carries a lysogenic bacteriophage. a) Protein F – mediates epithelial cell attachment  Acquired through respiratory droplet b) Lipoteichoic acid – bacterial adherence to the  Cardinal signs: diffused red rash on the upper respiratory epithelium chest and spreads to the trunk and extremities and strawberry colored-tongue ENZYMES AND TOXINS PRODUCED BY S.  Caused by the release of erythrogenic pyogenes toxin/strep pyrogenic exotoxin 1) HEMOLYSINS Red cheeks and rash Strawberry tongue A. STREPTOLYSIN O  “Oxygen labile”; highly antigenic  responsible for subsurface hemolysis on BAP  cause lysis of WBC, platelets, tissue cells  ASO test – detects recent infection w/ S. pyogenes B. STREPTOLYSIN S  “Oxygen stable”; non antigenic  responsible for surface hemolysis on BAP  DICK’S TEST (ERYTHROGENIC TOXIN)  it causes lysis of WBCs  susceptibility test for scarlet fever  (+) erythema – redness 2) DEOXYRIBONUCLEASES  degrading DNA via  SCHULTZ CHARLTON REACTION  hydrolysis of its phosphodiester backbone  diagnostic test for scarlet fever  used to diagnostic present scarlet fever 3) STREPTOKINASE  (+) “blanching phenomenon” – rash fade  a protein that binds to plasminogen and activates the production of plasmin 3) SKIN INFECTIONS  it allows the bacteria to move from clotted area  it activates a host blood-factor that dissolves  CELLULITIS fibrin clots  is a diffuse, spreading infection of subcutaneous skin tissue characterized by a defined area of redness (erythema) and accumulation of fluid (edema)  ERYSIPELAS  is an acute infection and inflammation of the dermal 4) HYALURONIDASE layer of the skin  to separate the tissue and spread the organism characterized by painful reddish patches that enlarge 5) PYROGENIC (ERYTHROGENIC) TOXINS and thicken with sharply  serotypes A, B, C defined edges  exotoxin B (cysteine protease) – degrades  may also lead to necrotizing fasciitis and proteins myositis “galloping gangrene”  RHEUMATIC FEVER  Neonatal sepsis  Postpartum infection  ACUTE GLOMERULONEPHRITIS OR BRIGHT’S  Osteomyelitis DISEASE  UTI  inflammatory disease of the renal glomeruli;  endocarditis results from the deposition of antigen-antibody complexes. DIAGNOSTIC TESTS DIAGNOSTIC TESTS  CAMP TEST  To differentiate S.agalactiae  BACITRACIN DISK TEST from other β-hemolytic  Differentiates S. pyogenes streptococci from other β-hemolytic  It uses β-lysin – producing group strain of S. aureus or disk  Result: (+) any zone of impregnated w/ β lysin inhibition  Result (+) arrow-head β-hemolysis near S.  Group C and G are also aureus growth / (+) bowtie appearance susceptible  HIPPURATE HYDROLYSIS TEST  SULFAMETHOXAZOLE-TRIMETHOPRIM TEST  S. agalactiae possesses the  Positive: Any zone of enzyme hippuricase inhibition  Reagent: sodium +ninhydrin  Negative: No Zone of  Results: (+) Purple color inhibition after adding Ninhydrin rgt  (Group A and Group B) (indicates hippurate hydrolysis)  (-) no color change  L-pyrrolidonyl-β-napththylamide (PYR) TEST GROUP C STREPTOCOCCI  L-Specific than Bacitracin test  Main source of streptokinase; animal pathogen  (+) bright/cherry red color  Species: S. equi, S. equisimilis, S. dysagalactiae, S.  (β-napththylamide) upon zoopedimicus adding 0.01% cinnamaldehyde reagent  (-) no color change GROUP D STREPTOCOCCI  Other PYR test positive organisms:  Enterococcus, Aerococcus, Gemella  Enterococci:  E. faecalis, E. faecium, E. avium, E. gallinarium GROUP B STREPTOCOCCI  Non enterococci:  Part of the normal flora of female genital tract and  S. bovis, S. equinus lower GIT  Enterococci are not highly pathogenic; cocci in  Nosocomially transmitted by unwashed hands of pairs and long chains mother or healthcare personnel.  Infection of fetuses and infants – infection during DIAGNOSTIC TEST passage through the colonized birth canal, and premature rupture of mother’s membranes  GROWTH IN BILE ESCULIN MEDIUM  Reagent: Esculin + 1-4% bile  On culture, it is grayish white mucoid w/ small zone salt of beta hemolysis  Result: (+) Black color  Species: S. agalactiae (BOTH enterococci and non  Virulence factor: capsule (sialic acid – signifiant enterococci) component of the capsule)  Enzymes: hemolysin, CAMP factor, neuraminidase, deoxyribonuclease, hyaluronidase and protease  6.5% NaCl (nutrient broth base) test  Result: (+) turbididty – DISEASES AND INFECTIONS enterococci (also PYR +)(-) non enterococci  Pneumonia  Neonatal Meningitis  LAP Test  This group of organism were found as satellites  Detects for the ability of around an organism that produces pyridoxal – E. the bacteria to hydrolyze coli, Klebsiella spp.,Enterobacter spp., yeasts Leucine-β-naphthylamide  They produce satellatism w/ Staphylococcus by enzyme leucine  Opportunistic pathogens of low virulence aminopeptidase to  Variable morphology – gram (+) to gram (-) to β-naphthylamide. gram variable; pleomorphic forms  Positive: Development of a  It causes 5-6% endocarditis red color within 1 minute after adding cinnamaldehyde reagent STREPTOCOCCUS SPP.  LABORATORY DIAGNOSIS  Negative: No color change or development of slight yellow color 1) Gram Stain (Aerococcus and Leuconostoc) 2) Culture – BAP, PEA, CNA, CAP NOTES  For isolation of Group A streptococci from throat swab, BAP w/ SXT is used to suppress the growth of  Enterococci – (+) bile esculin, growth in 6.5% NaCl. normal flora. PYR test and LAP test; vancomycin resistant  To detect genital carriage of Group B streptococci  Leuconostoc, Pediococcus, Globicatella, S. urinalis, during pregnancy, Todd Hewitt broth w/ Lactococcus – (+) growth in bile esculin and 6.5% antibiotics(gentamicin, nalidixic acid or colistin and NaCl nalidixic acis) is used to suppress vaginal flora.  All enterococci isolated from human hydrolyze PYR  Visualization of beta hemolysis is enhanced by anaerobic condition (BAP should be inoculated by  Isolation of S. bovis from a blood culture may be the stabbing the inoculating loop into the agar several first indication that the patient has an occult tumor in times) the GI tract (GI cancer)  CAP is incubated w/ 5-10% CO2  85% of Group B streptococci is (+) w/ growth in 6.5%  Abiotrophia will not grow on BAP or CAP unless NaCl but (-) in bile esculin test pyridoxal (B6) is supplied.  E. faecalis requires cyanocobalamin (B12) as growth  Streptococci has tendency to produce increase factor. amount of lactic acid and other organic acid from fermentation of sugar resulting to acidic medium and GROUP F and G eventually their growth is inhibited.  Minute streptococci w/ wide zone of beta hemolysis 3) Susceptibility Test – bacitracin disk test SXT test  Species: S. anginosus 4) CAMP and Hippurate test 5) Bile Esculin and Salt Tolerance Test  VIRIDANS STREPTOCOCCI 6) Serological Test  Alpha hemolytic streptococci that lack the a) Latex agglutination lancefield group antigens and do not fall on the b) ASO titer test criteria for S. pneumoniae, can be c) ELISA non-hemolytic. d) Co-agglutination  Oropharyngeal commensals  Opporunistic pathogens of low virulence  Streptococcus pneumoniae  Glucans and dextrans – enhance attachment to  Diplococcus/pneumococcus host cell surfaces  Gram (+) cocci in pairs, oval or lancet shape;  Laboratory tests: bile insoluble, optochin facultatively anaerobe resistant, no growth in 6.5% NaCl, (-) inulin  Causative agent of lobar pneumonia fermentation and PYR (-)  Considered part of the normal flora (25-50%) of  Species: S. mutans, S. salivarius, S. mitis the URT of preschool children  Infections: subacute endocarditis, dental carries  Most common bacterial pneumonia in elderly as (S. mutans) well as in patients w/ underlying disease.  Most common cause of bacterial meningitis in  ABIOTROPHIA adults  Pyridoxal-dependent or Vit B6 dependent and  Common isolate both as a pathogen and as a symbiotic streptococci member of the normal respiratory tract.  Formerly known as nutritionally variant  Principal virulence factor: antiphagocytic streptococci (NVS) capsular polysaccharide – type 3 strains  Thiol compounds – cystein, Vit B6 and pyridoxal   Opsonization of the capsule renders the  The antipnemococcal organism non virulent serum is mixed w/  The capsule is antigenic and can be identified w/ sputum, CSF and other appropriate antiserum; it is composed of sources along w/ hyaluronic acid. methylene blue  Alpha hemolytic colonies, mucoid, flattened with  Examined under OIO depressed center.  “dome-shaped,” glistening, wet, mucoid – young colonies 4. Mouse Virulence Death of the animal  “coin w/ a raise rim” – old colonies (due to autolytic changes)  Dimple-shaped/donut-shaped colonies 5. Inulin Fermentation (+) Fermentation  Enzymes: hemolysin, immunoglobulin A Test protease, neuraminidase and hyaluronidase INFECTIONS/DISEASES PRODUCED 1) Pneumonia  pneumonia due to S. pneumoniae is not usually a primary infection but rather a result of disturbance of the normal defense barriers. 2) Meningitis 3) Otitis media 4) Bacteremia 5) Endocarditis 6) Peritonitis DIFFERENTIAL TEST RESULT 1. Optochin Susceptibility/ P disk Test > Or = 14mm  Presumptive test  Ethylhydroxycuprein  hydrochloride  BAP (sensitivity media) 2. Bile Solubility  Confirmatory test  Differentiates pneumococcus from viridans streptococci (+) soluble  Sodium desoxycholate  When a heavy suspension of pneumococcus is added to bile salt, the cloudiness of the broth clears after 3 hrs incubation. 3. Neufeld Quellung SWELLING CAPSULE Reaction