Transition Microbiology Revision Flashcards
Define virulence
Degree of pathogenicity
Name the 4 bacteria shapes
Coccus
Bacillus
Fusiform
Spirochaete
What is the structure / appearance of gram positive bacteria? What type of toxin do they produce?
Purple
Thick peptidoglycan layer
Produce exotoxin inside cell and export out
What is the structure / appearance of gram negative bacteria? What type of toxin do they produce?
Pink
Thin peptidoglycan layer + LPS in outer membrane
Produce endotoxin
What is the appearance of strep on film?
Purple gram positive cocci in chains
How are strep classified? Be specific
Haemolysis
Alpha partial - green - viridans, pneumoniae
Beta complete - clear - group A strep pyogenes
Gamma none - group B enterococci
How are staph classified? Be specific
Coagulate
\+ve = aureus -ve = others e.g. epidermidis
What is the appearance of staph on film?
Purple gram positive cocci in clusters
What is the best antibiotic against s. aureus? What is used in allergies?
Fluclox
Allergy vanco
What is the appearance of clostridium on film?
Gram positive anaerobic bacilli
Produces spores
What is the best antibiotic against clostridium?
Metronidazole
What is the appearance of neisseria (gonococcus and meningitides) on film?
Gram negative aerobic diplococci
How are gram negative bacilli classified?
Lactose positive = coliform
Lactose negative = h. pylori, pseudomonas
What is a coliform? Include examples
Gram negative aerobic bacilli. Some are gut commensals e.g. e.coli, Klebsiella, proteus, enterobacter. Some are pathogens e.g. salmonella, shigella, e.coli 0157
What antibiotic is used against coliforms?
IV genta then switch to PO co-trimoxazole
Name the 2 strict aerobes
Pseudomonas, legionella
What antibiotic is used against strict anaerobes?
Metronidazole
Name the 4 C antibiotics? What is the risk?
Cephalosporins e.g. ceftriaxone
Co-amoxiclav
Ciprofloxacin
Clindamycin
C. diff
What are the 2 components of co-amoxiclav? What gram negative bacilli does it not protect against?
Amoxicillin + clavulanic acid
Pseudomonas
How are penicillins excreted? What is their mechanism?
Renal
Inhibit beta lactamase
Give an example of a cephalosporin. What is their mechanism?
Ceftriaxone
Inhibit beta lactamase
What antibiotic is only effective against gram positives?
Vancomycin
What is the mechanism of vancomycin?
What type of bacteria is it active against?
What routes is it available?
Inhibits peptidoglycan synthesis
Only gram positives
Only IV
How is gentamicin excreted? What is it effective against? What are the side effects? What is used if genta is contraindicated? When is genta contraindicated?
Kidneys Gram negative aerobes Kidney / CNVIII damage Aztreonam CKD / pregnant
Give an example of a tetracycline
What routes is it available?
How is it excreted?
When is it contraindicated?
Doxycycline
PO only
Liver
Pregnancy and children
What is metronidazole active against?
True anaerobes and some protozoa
Which antibiotic inhibits folic acid synthesis?
Trimethoprim
Define sepsis
Life-threatening organ dysfunction due to dysregulated host response to infection
What would an ABG show in sepsis? Why?
Metabolic acidosis
Lactic acid from hypoperfusion and anaerobic metabolism
What effect does sepsis have on TPR, CO and the circulation volume?
Decreased TPR
Decreased CO
Hyperdynamic circulation
How is sepsis diagnosed?
NEWS >5 + presumed infection
qSOFA is only used as a prognostic indicator in ICU. T or F
True
What is the sepsis 6? What time frame should it be done in?
Less than 1 hour
Oxygen IV empirical ABx Blood culture Fluid 0.9% 500ml NaCL FBC, lactate, biochemistry Monitor UO
How many fluid boluses should be given in sepsis? What type of fluid should never be given?
Till normal BP
Never 5% dextrose
In sepsis management, if hypotension persists despite euvolaemia, what drugs (name and class) should be initiated? By what route?
Inotrope/ vasoconstrictor;
Noradrenaline alpha agonist
Adrenaline alpha/ beta agonist
Central venous catheter
What is the management of mild and severe CAP? Include penicillin allergies
Mild
1st PO amox
2nd PO doxy
Severe
1st IV co-amox + PO doxy
2nd IV levofloxacin
What test is done to diagnose C. diff?
Stool toxin test
What is the management of severe and non-severe c. diff?
Non-severe PO metron
Severe PO vanco
What is c. diff infection? Why does it recur?
ABx induced pseudomembranous colitis
Spores
What is the management of peritonitis? Include penicillin allergy, what each is against and the PO switch
Amox - gram +ve enterococci
Genta - coliforms
Metron - anaerobes
Allergy vanco + genta + metron
PO switch to co-trimox + metron
What criteria diagnoses endocarditis? What investigations (par blood tests) are done?
Duke criteria
6 cultures
Echo
What is the commonest cause of the following endocarditis scenarios
- Native valve acute
- Native valve subacute
- Intra-op
- Prosthetic valve
- PWID
- Native valve acute S. AUREUS
- Native valve subacute VIRIDANS / ENTEROCOCCI
- Intra-op EPIDERMIDIS
- Prosthetic valve EPIDERMIDIS
- PWID S. AUREUS
What valve is effected in PWID endocarditis?
Tricuspid
What is the management of the following endocarditis scenarios?
- Mild native valve
- Septic native valve
- Prosthetic valve
How long are ABx given?
- Mild native valve IV amox + genta
- Septic native valve IV fluclox
- Prosthetic valve IV vanco + PO rifampicin + IV genta
6 weeks
What is the management of severe and non severe HAP?
Non-severe PO amox + metron
Severe AGM
What is the management of mild and severe DM foot? Include penicillin allergy
Mild
1st fluclox
2nd doxy
Severe
1st fluclox + metron
2nd doxy + metron
What is the bacillus cereus buzzword? What is the management?
Reheated rice
no ABx
What infection is associated with petting zoos and BBQs?
E coli 0157
What is the management of E coli O157 infection? What are the complications?
No ABx
HUS
AKI
“Disproportionate pain to wound”
Necrotizing fasciitis
Define septic shock
Hypotension on vasopressor + lactate>2 despite euvolemia
What is the likely organism and Mx of septic arthritis and osteomyelitis?
IV 4-6wk fluclox
