Microbiology Flashcards
Immediate antibiotic for suspected meningitis?
Benzylpenicillin.
Beta-haemolytic gram-positive strep, Lancefield group A?
Streptococcus pyogenes
Antibiotic for pregnant woman with UTI?
Nitrofurantoin (but not in third trimester).
What nutrient agar is used to grow mycobacterium tuberculosis?
Lowenstein-Jensen
C. diff microbiology characteristics?
- anaerobic
- gram positive
- rods
Pseudomonas microbiology characteristics?
- aerobic
- rod
- non-lactose fermenting
- positive oxidase test
Proteus microbiology characteristics?
- facultatively anaerobic
- non-lactose fermenting
- negative oxidase test
- gram-negative rod
Salmonella microbiology characteristics?
- gram-negative rod
- facultatively anaerobic
- non-lactose fermenting
- negative oxidase test
Shigella microbiology characteristics?
- gram-negative rod
- facultatively anaerobic
- non-lactose fermenting
- negative oxidase test
Most common cause of infective endocarditis in adults?
- Staph aureus
- Strep viridans
- Coagulate negative staph
Strep viridans microbiology?
Optochin resistant alpha-haemolytic streptococcus.
Streptococcus pneumoniae microbiology?
Optochin sensitive alpha-haemolytic streptococcus.
Test used to distinguish between staphylococcus and streptococcus?
Catalase
Gram positive diplococcus causing meningitis?
Streptococcus pneumoniae
Gram negative diplococcus causing meningitis?
Neisseria meningitidis
Gram negative bacilli?
- E. coli
- campylobacter
- pseudomonas
- salmonella
- shigella
- proteus
Gram negative cocci?
- neisseria
- moraxella (catarrhalis)
Gram positive cocci?
- staphylococci
- streptococci
- enterococci
Gram positive bacilli?
- bacillus anthracis
- corynebacterium diphtheriae
- listeria monocytogenes
- clostridium
Intracellular bacteria?
- coxiella
- chlamydia
- rickettsia
Are the standard staphylococci / streptococci aerobic or anaerobic?
Aerobic
Coagulase positive staph?
Staph aureus
Coagulase negative staph?
Staph epidermidis
Staph saprophyticus
Alpha haemolytic strep?
- s. pneumoniae
- viridans strep
Beta haemolytic strep?
s. pyogenes
Group A strep?
s. pyogenes
Which gram positive bacilli are aerobic?
- corynebacterium diphtheriae
- listeria monocytogenes
- bacillus anthracis
Which gram positive bacilli are anaerobic?
Clostridium
How can aerobic gram negative bacilli be sub-classified?
- lactose fermenters
- non-fermenters
Are gram negative bacilli mostly aerobic or anaerobic?
Aerobic
Lactose fermenters?
- E. coli
- klebsiella
Non-fermenters?
- salmonella
- shigella
- proteus
- pseudomonas
Other aerobic gram negative bacilli?
- campylobacter
- helicobacter
- legionella
- haemophilus
Stain for mycobacteria?
Ziehl-Neelsen
How to distinguish pseudomonas from other gram negative aerobic bacilli (non-lactose fermenting)?
Oxidase test - pseudomonas is oxidase positive.
Agar for lactose fermentation?
MacConkey
Most common pathogens causing CAP?
- strep pneumoniae
2. haemophilus influenzae
What is chocolate agar?
Blood agar with haemolysed RBCs.
How is legionella tested for?
Urine antigen test.
What does acid-fast mean?
Bacilli are red stained on Ziehl-Neelsen stain, even after washing with acid and alcohol.
Bacterial causes of infection / colonisers in COPD?
- s. pneumoniae
- h. influenzae
- moraxella catarrhalis
Viral causes of infection in COPD?
- respiratory syncytial virus
- influenza
- rhinovirus
- seasonal coronaviruses
Cause of bronchiectasis?
Severe bacterial infection - whooping cough (bordatella pertussis), TB.
Colonising organisms in bronchiectasis?
- h. influenzae
- s. pneumoniae
- m. catarrhalis
- pseudomonas
Predominant colonising organism in neonates / infants with CF?
Staph aureus
Predominant colonising organism in infants / children with CF?
Haemophilus influenzae
Predominant colonising organism in older children and adults with CF?
Pseudomonas
Bacterial responsible for ‘culture negative’ endocarditis?
- coxiella burnetii
- chlamydia psittaci
Most common cause of IE in IVDU?
Staph aureus
Most common organism found in IE blood cultures?
- Staph aureus
- Strep viridans
- Staph epidermidis / staph saprophyticus.
Cause of IE found in the oral cavity?
Viridans strep
Source of coagulase negative staph in IE?
Contamination of IV lines.
Criteria for IE diagnosis?
Modified Duke’s criteria
Criteria for ‘definite’ IE?
- 2 major
- 1 major, 3 minor
- 5 minor