Gram-positive cocci and diseases
|Name of Gram-positive cocci||Diseases|
|Staphylococcus aureus||Surgical-site infections, skin infection, hospital-acquired pneumonia, osteomyelitis, toxic-shock syndrome, necrotizing fasciitis, food-poisoning, infective arthritis|
|Streptococcus pyogenes||Acute pharyngitis (strep-sore throat), impetigo, erysipelas, necrotizing fasciitis, myositis,|
|Streptococcus pneumoniae||Bacterial pneumonia, meningitis, otitis media, sinusitis, bronchitis, bacteremia, scarlet fever, rheumatic fever, post-streptococcal glomerulonephritis, and streptococcal toxic shock syndrome|
|Streptococcus agalactiae||Postpartum infection and neonatal sepsis|
|Enterococcus faecalis||Urinary tract infections, bacteremia, ocular infections, mitral valve endocarditis, meningitis (rarely)|
Staphylococcus saprophyticus causes urinary tract infections (UTI), especially cystitis in sexually active young women.
The viridans streptococci are another important Gram-positive cocci comprising a large group of bacteria and are commensals of mouth.
Enterococcus is gram-positive cocci in chains and is catalase negative. It causes infections of Urinary tract and biliary tract.
Streptococcus agalactiae (GBS), is a beta-hemolytic, CAMP test positive, gram-positive cocci. It can cause severe infection in newborns.
Furazolidone disk test is used to differentiate staphylococci (sensitive) from micrococci (resistant).
Major virulence factors of S. aureus are capsule, teichoic acid, protein A, enterotoxin, TSST-1, coagulase, hyaluronidase, etc.
S. pneumoniae virulence factors include capsular polysaccharide, C carbohydrate antigen, pneumolysin, autolysin.
Pus aspirate is the preferred sample. S. aureus, Strep pyogenes, and members of Enterobacteriaceae are major pathogens.
Pneumococcal urinary antigen testing is a rapid assay that detects Streptococcus pneumoniae antigen (C-polysaccharide) in the urine of patients.
Major virulence factors of S.pyogenes are adhesions, M protein, hemolysins, pyrogenic exotoxins and spreading factors.
Micrococcus is lysostaphin and furazolidone resistant, bacitracin sensitive and microdase positive. Find the results of Staphylococcus.
This group A beta-hemolytic streptococci is bacitracin sensitive and causes strep sore throat, rheumatic fever, and PSGN.
Staphylococci are catalase positive, gram positive cocci in clusters but Streptococci are catalase negative and may appear in pairs or chains.
Campylobacter jejuni, Listeria monocytogenes, Gardnerella vaginalis, and Streptococcus agalactiae are positive for hippurate hydrolysis test.
Beta hemolytic streptococci are arranged into twenty (20) groups A-U without I and J (i.e. A through H and K through V).
Bile-esculin test is widely used to differentiate Enterococci and Non-enterococcus group D streptococci from non-group D viridans group streptococci.
Salt tolerance test determines the ability of an organism to grow in high concentrations of salt (6.5%).
Some gram-positive cocci such as Enterococcus produces enzyme L-pyrroglutamylaminopeptidase that hydrolyze PYR substrate.
Catalase test is used to distinguish among Gram-positive cocci. Staphylococci are catalase-positive but Streptococci are catalase-negative.
Gram positive bacteria appear purple and gram-negative bacteria appear pink when stained by Gram-staining methods.
Rapid latex agglutination test for the qualitative and semi-quantitative determination of anti-streptolysin-O antibodies (ASO) in serum.
Novobiocin test is used to differentiate CONS and presumptively identify the isolate as Staphylococcus saprophyticus (novobiocin resistant).
Optochin (ethylhydrocupreine hydrochloride) lyses pneumococci (positive) but alpha-streptococci are resistant (negative).
Bile solubility test differentiates S. pneumoniae (positive) from alpha-hemolytic streptococci (negative).
Bacitracin test differentiates S. pyogenes (inhibited) from other beta-hemolytic streptococci.
Pneumococcus is lanceolate shaped gram-positive cocci and causes pneumonia and meningitis. Its is optochin sensitive and bile soluble.
Catalase test, oxidase test, MUG test, optochin sensitivity test, bacitracin sensitivity test, coagulase test, etc are some of the common biochemical tests.
Bacteria exist in four basic morphologies: cocci; rod-shaped cells, or bacilli; spiral-shaped cells, or spirilla; and comma-shaped cells, or vibrios.
Teichoic acids are fibers of glycerol phosphate or ribitol phosphate and is located in the cell-wall of gram-positive bacteria.
Frequent colonizer of skin, S. aureus is a major cause of surgical wound infection. This gram-positive cocci is catalase and coagulase +ve.