GRAM POSITIVE COCCI Flashcards
Staphylococci overview - What are the general characteristics of staphylococci?
gram-positive cocci grows in grape-like clusters
Staphylococcus epidermidis - What is the role of Staphylococcus epidermidis in human health?
Normal flora of skin and mucosa; occasionally pathogenic.
Staphylococcus Aureus - What is the pathogenic role of Staphylococcus aureus?
It is pathogenic and often found as normal flora, causing serious infections, in immunocompromised individuals, like:
- pneumonia
- osteomyelitis
- sepsis, particularly in immunocompromised individuals.
Staphylococcus Saprophyticus - Where is Staphylococcus saprophyticus found and what infections does it cause?
Found in the environment and on skin; causes urinary infections.
Staphylococcus Aureus Colony Growth - How does Staphylococcus aureus grow in culture?
Produces 2-3 mm colonies in 24 hours on simple media (agar, blood-agar) at 37ºC.
Staphylococcus Aureus Toxins - Name the main toxins produced by Staphylococcus aureus.
Cytotoxins (α, β, δ, γ, P-V leukocidin)
- enterotoxins (A-E, G-I)
- exfoliative toxins (ETA, ETB)
- Toxic Shock Syndrome Toxin 1.
Staphylococcus Aureus Enzymes - What enzymes are produced by Staphylococcus aureus?
- Coagulase
- Beta-lactamase (penicillinase)
- hyaluronidase
- staphylokinase
Staphylococcus Aureus Resistance - Why is Staphylococcus aureus concerning in hospitals?
85-90% of strains are penicillin-resistant and it causes nosocomial infections, often in immunocompromised patients.
Staphylococcus Aureus Disease Manifestations - What diseases does Staphylococcus aureus cause?
Localized purulent infections
- Pustules
- boils
- pneumonia, endocarditis, septicima
- toxic shock syndrome, food poisoning, scalded skin syndrome.
Staphylococcus Epidermidis Infections - In which patients can Staphylococcus epidermidis become pathogenic?
In immunocompromised patients, it can cause:
- post-operative infections
- endocarditis
-shunt infections.
Streptococci Overview - What are the general characteristics of Streptococci?
Gram-positive cocci, usually in pairs or chains, fastidious in nutritional requirements (blood agar).
Streptococcus Haemolysis Types - What are the types of haemolysis in streptococci?
- Alpha-haemolysis (greenish-brown zone)
- beta-haemolysis (clear zone)
- non-hemolytic strains.
Streptococci Lancefield Classification - How are streptococci classified?
- haemolytic properties (alpha, beta, non-hemolytic)
- carbohydrate C-antigen (Groups A-T).
Streptococcus M-protein - What is the role of M-protein in beta-haemolytic streptococci?
M-protein is an important virulence factor, antiphagocytic, and degrades complement C3b
- It is found mainly in Group A streptococci.
Streptococcus pyogenes Overview - What group and hemolysis type is Streptococcus pyogenes, and what diseases does it cause?
Group A, beta-hemolytic; causes sore throat, skin infections, puerperal fever, septicaemia
- complications: acute glomerulonephritis and rheumatic fever.
Streptococcus pyogenes Toxins - What toxins are produced by Streptococcus pyogenes and their effects?
Streptolysins (O and S) - toxic for neutrophils and macrophages
- Streptococcal Pyrogenic Exotoxins (SpeA, SpeB, SpeC) - cause scarlet fever rash.
Streptococcus pyogenes Enzyme - What enzyme does Streptococcus pyogenes produce, and what is its effect?
Hyaluronidase - helps spread infection by breaking down connective tissue.
Streptococcus pyogenes Antibiotic Sensitivity - What antibiotic is most effective against Streptococcus pyogenes?
Penicillin G, as most strains are sensitive to it.
Streptococcus agalactiae (Group B) - What infections does Streptococcus agalactiae (Group B) cause in neonates (newborns)?
Early septicaemia (high fatality) and delayed meningitis (with potential neurological effects).
Streptococcus faecalis (Group D) - What infections can Streptococcus faecalis (Enterococcus) cause?
Urinary tract infections, septicaemia, endocarditis, and meningitis, often resistant to many antibiotics.
Viridans Streptococci -Where are Viridans streptococci found and what do they cause?
Found in the oral cavity; may cause endocarditis in people with damaged heart valves.
Streptococcus pneumoniae - What disease does Streptococcus pneumoniae cause, and who is at higher risk?
Causes lobar pneumonia and meningitis
- more common in infants, the elderly, and alcoholics.
Pneumococcal Vaccine -How can Streptococcus pneumoniae infections be prevented?
Vaccination with a polyvalent pneumococcal vaccine (23 serotypes) for high-risk individuals like the elderly and alcoholics.
Neisseria meningitidis Overview - What infections does Neisseria meningitidis cause?
- Meningitis
- septicaemia
- Waterhouse-Friderichsen syndrome (adrenal hemorrhage).
Neisseria meningitidis Vaccine - What vaccine prevents Neisseria meningitidis infections?
Conjugated vaccine for serogroups A, C, Y, and W135, recommended for children and high-risk individuals.
Neisseria meningitidis Serogroups - What are the main serogroups of Neisseria meningitidis?
A, B, C, X, Y, W135.
Neisseria gonorrhoeae Infections - What diseases are caused by Neisseria gonorrhoeae?
- Genital infections (gonorrhoea)
- pelvic inflammatory disease (PID)
- disseminated gonococcal infection (DGI)
- neonatal infections (ophthalmia neonatorum).
Gonorrhoea Diagnosis - How is Neisseria gonorrhoeae diagnosed?
Gram stain of urethral discharge (men) or culture from swabs (women), using selective media like Thayer-Martin agar.
Gonorrhoea Treatment - What is the recommended treatment for gonorrhoea?
Ceftriaxone or cefixime with doxycycline or azithromycin.
Gonorrhoea Resistance - What is a growing concern regarding Neisseria gonorrhoeae treatment?
Increasing resistance to penicillin, especially in Southeast Asia, West Africa, and parts of the U.S. and Canada.
