bacterial iddentificaton Flashcards
draw the diagram fo all the gram positive bacteria
what does a double zone of hemolysis n blood agar denote ?
clostridium pefergenines
What is the first step in identifying streptococci in the lab?
Determine if the bacterium is Gram-positive cocci and catalase-negative.
What test differentiates Streptococcus from Staphylococcus?
The catalase test. Streptococcus is catalase-negative, while Staphylococcus is catalase-positive.
How do you differentiate Viridans streptococci from Streptococcus pneumoniae
Viridans streptococci: Optochin-resistant, bile-insoluble.
Streptococcus pneumoniae: Optochin-sensitive, bile-soluble.
What infections are caused by Viridans streptococci?
Dental caries and subacute endocarditis.
What infections are caused by Streptococcus pneumoniae?
Meningitis, otitis media, pneumonia, and sinusitis.
MOPS
How do you differentiate Group A Streptococcus (GAS) from Group B Streptococcus (GBS)?
GAS (Streptococcus pyogenes): PYR-positive, bacitracin-sensitive
GBS (Streptococcus agalactiae): PYR-negative, CAMP-positive
What diseases are caused by Streptococcus pyogenes (GAS)?
Scarlet fever, rheumatic fever, PSGN (post-streptococcal glomerulonephritis)
What diseases are caused by Streptococcus agalactiae (GBS)?
Neonatal sepsis & meningitis, UTI.
How do you differentiate Enterococcus from Streptococcus gallolyticus
Enterococcus: Grows in bile & 6.5% NaCl, PYR-positive.
Streptococcus gallolyticus: Grows in bile but NOT 6.5% NaCl, PYR-negative.
What infections are associated with Enterococcus?
UTI, cholecystitis, and subacute endocarditis.
What infections are caused by Staphylococcus aureus?
Inflammatory diseases: Skin infections, organ abscesses, pneumonia, infective endocarditis, septic arthritis, osteomyelitis.
Toxin-mediated diseases: Toxic shock syndrome (TSST-1), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (enterotoxins).
What is MRSA, and why is it important?
Methicillin-resistant Staphylococcus aureus (MRSA) is a serious cause of hospital- and community-acquired infections.
Resistance is due to altered penicillin-binding proteins (mecA gene).
Some strains release Panton-Valentine leukocidin (PVL), which kills leukocytes and causes tissue necrosis.
What is Staphylococcal Toxic Shock Syndrome (TSS)?
Caused by TSST-1 superantigen
Binds MHC II and T-cell receptor, leading to cytokine storm
Symptoms: Fever, vomiting, diarrhea, rash, desquamation, shock, multi-organ failure
Risk factors: Prolonged tampon use, nasal packing
