Microman Flashcards
When is Sensitivity testing of the causative organism is important ?
For deep or invasive infections and/or those not responding to treatment. Please send relevant samples – especially blood cultures wherever possible BEFORE antibiotics are given.
When deciding on antibiotic treatment what is it important to check a patient has ?
A previous positive ALERT organism like an ESBL, MRSA, CPE etc Check to see if patients have travelled abroad – especially recently (within 12 weeks): they may be at risk of different infections or infections with different resistance patterns to local patterns
Therapeutic drug monitoring is required for what drugs ?
Gentamicin & Vancomycin
Are there restricted antibiotics ?
Yes e.g. meropenem
If a patient is not improving on antibiotic treatment what should you check?
Check: correct antibiotic(s), dose, route. Have you got source control or is there an abscess, deep infection, medical device with biofilm or new infection or selection out of resistant strains?
Before you call microbiology for advice what information should you know?
Main complaint & history; current & recent antibiotic history
Initial assessment & Investigations; radiology, samples to determine infection focus
CRP, WCC; results & trends
Renal function; allergy
Observations (NEWS, SEPSIS 6, CURB65 etc)
MICRO
What are the main organisms which cause meningitis ?
Pneumococcus, meningococcus & if ≥60 years: Listeria
What is the main cause of encephalitis ?
Herpes simplex
What antiobitc group are both pneumococci and meningococci sensitive too ?
Penicillin
Why is ceftriaxone chosen as the 1st line treatment of meningitis ?
- Because of the need for high CSF levels to be maintained & the ease of dosing (twice a day).
- It also provides better cover for the rare strain that may have borderline sensitivity to penicillin
What antibiotics is listeria resistant to and what is it sensitive to ?
Resistant to cephalosporins and sensitive to amoxicillin
What is the high dose & frequent dosing (4 hourly) of amoxicillin needed for treatment of meningitis caused by listeria ?
Because of the need for high CSF antibiotic levels
What antibiotic could be used instead of amoxicillin in the treatment of meningitis but is not used in tayside ?
Ampicillin
What drug is herpes simplex sensitive to and what mode must it be given as ?
IV aciclovir
What are the main micro-organisms which cause epiglottitis ?
Haemophilus influenzae and streptococci
What are the main micro-organisms which cause tonsillitis ?
Group A streptococci
What are the main micro-organisms which cause Sinusitis ?
Pneumococcus
What are the main micro-organisms which cause Acute ottitis media ?
Pneumococcus, Haemophilus influenzae
What are all beta-haemolytic streptococci [groups A B C & G] exquisitely sensitive to?
Penicillin
In ENT infections Pneumococci & meningococci are sensitive to penicillin but amoxicillin has better absorption when given by what route ?
Orally
What are Most (77%) Haemophilus influenzae are sensitive to and state what the commenst resistance this organism has to that antibiotic and therefore state why a different antibiotic is used to treat life-threatening illnesses such as epiglottitis
- Most are sensitive to amoxicillin (not penicillin).
- Commonest resistance is betalactamase production.
- Life threatening illnesses like epiglottitis are therefore treated with ceftriaxone for high tissue levels, ease of dosing and better empiric cover for those that are amoxicillin resistant
What are Most (97%) Haemophilus influenzae and 87% of pneumococci sensitive to ?
Doxycycline
What are the main causative organisms of mild/moderate Community acquired pneumonia (CAP)?
Pneumococcus and Haemophilus influenzae
What are the main causative organisms of severe CAP?
Pneumococcus, Haemophilus influenzae, coliforms and atypicals (Legionella, Mycoplasma, Chlamydia pneumoniae, Coxiella)
Remember Staph aureus pneumonia post influenza and the PVL producing strains of Staph aureus that can produce severe pneumonia in children and young adults especially please contact micro/make clear on form to add extra tests for this
What are the main causative organisms of an acute exacerbation of COPD?
Pneumococcus and Haemophilus influenzae
What are the main causative organisms of hospital acquired pneumonias (HAP)?
Pneumococcus, Haemophilus influenzae and coliforms. Legionella can be hospital acquired
Co-amoxiclav provides cover for what organisms for those with a severe CAP?
Haemophilus influenzae & coliforms (not ESBLs or CPEs though)
Doxycycline is used for covering what type of organisms in CAP with the exception of what?
Atypicals (not used for Legionella)
Levofloxacin use is restricted to what CAP protocol and what organism cover does it provide ?
Its use is restricted to severe CAP protocol and has good cover against MSSA, Haemophilus influenzae, pneumococci, coliforms & legionella
What type of cover in pneumonia treatment does clarthiromycin provide ?
Atypical cover
In Pneumonia treatment which is preferred - doxycycline or clarthiromycin?
Doxycycline
For Native valve acute endocarditis what is the main causative organism and what should be done ?
Staph.aureus - take 2 sets blood cultures & start antibiotic within the hour
What is the main causative organisms of native valve subacute endocarditis and what tests should be done if the patient is stable ?
Viridans streptococci, enterococci :3 sets blood cultures 6 hours apart if patient stable
What are the main causative organisms of prosthetic valve endocarditis ?
MRSA and coagulase negative staphylococci
What drugs are MRSA resistant to ?
Flucloxacillin and all beta lacatams
What may coagulase negative staphylococci be resistant to ?
The have an unpredictable resistance to flucloxacillin
What are the important points to remember about endocarditis treatment ?
- Needs high dose IV antibiotics
- Prolonged duration of antibiotics (4-6weeks)
- Bactericidal antibiotics should be used (rather than slowing growth) to penetrate vegetations, eliminate bacteraemia and reduce risk of septic emboli
For acute native valve endocarditis Staph. Aureus is targeted with high dose flucloxacillin because ?
valve destruction & emboli are a risk
Most enterococci are sensitive to what drug? despite this what is still required ?
Most Enterococci are sensitive to amoxicillin but testing is required
Staph aureus bacteraemias are treated with what and why?
2 weeks IV therapy to prevent native valve endocarditis
Line removal is required in when what organisms are causing a CVC infection?
fungal, coliform, Pseudomonas, Staph aureus
What is the causative organisms of C.diff ?
Clostridum difficile
What are the main causative organisms of Peritonitis/biliary tract sepsis/intrabdominal infections?
Polymicrobial coliforms, anaerobes & enterococci
What are the main causative organisms of Spontaneous bacterial peritionitis?
coliforms +/- anaerobes, sometimes Strep pneumonia
Give 2 examples of non-infectious causes of diarrhoea
E.coli 0157 and campylobacter
What are the important points to remember about E.coli 0157 infections ?
- Notify Health Protection & Infection Control on suspicion
- Discuss children with bloody diarrhoea/HUS/confirmed 0157 with on call paediatric doctor. Discuss adults who are unwell with possible/confirmed HUS with Infectious Diseases
- HUS is more common in under 5s and over 65s year olds. Most develop 6-8 days post onset of symptoms- unlikely after >14 days
- It is more common in those with bloody diarrhoea or who are unwell Faeces for culture & reference laboratory tests
- Haematology; FBC, film for fragmented blood cells for suspected HUS or confirmed 0157
- Biochemistry: U&E, LDH, CRP for baseline assessment
What antibiotic are anerobes generally sensitive to ?
Metronidazole
what antibiotics are coliforms generally sensitive to ?
gentamicin and most to aztreonam
Only 47% of E coli are sensitive to what antibiotic and therefore why is this important to remember when treating GI infections ?
Only 47% of E coli are sensitive to amoxicillin; when you stop gentamicin you may not have adequate gram negative cover
65% of E coli are sensitive to what?
Co-trimoxazole and trimethoprim (which can be used as a single agent rather than co-trimoxazole in uncomplicated UTI)
Enterococci are sensitive to co-trimoxazole but what is required first ?
Testing because they rarely cause infection without coliforms
ESBLs are resistant to most what?
penicillins & cephalosporins including aztreonam, co-amoxiclav & pip-tazobactam
Most ESBLs are sensitive to what?
temocillin (& meropenem available on infection specialist advice only)
Sensitivity of ESBLs to co-trimoxazole is what?
Unpredictable
What are the main causative organisms of uncomplicated female lower UTI’s and male (uncatheterised) UTI’s?
Coliforms and Enterococci
What are the main causative organisms of complicated UTI infections such as pyelonephritis, urosepsis?
coliforms, Pseudomonas aeruginosa, enterococc
Why should you NOT send a catheter urine sample unless you consider this to be a source of infection and the patient has signs or symptoms of infection?
They will nearly always yield bacteria, treatment does not improve outcome & may lead to side effects (&C difficile)
if complicated infection, or male UTI what investigations should you send for ?
Send blood cultures and urine for culture
Do uncomplicated UTI’s in females always require cultures ?
No unless recurrent UTI’s
Why should Nitrofurantion not be used for anything other than uncomplicated lower UTIs in females & uncatheterised males?
Because it has no kidney tissue penetration & is not excreted in urine in renal impairment
What antibiotic can be used for oral treatment of ESBLs where pivmecillinam, co-trimoxazole, nitrofurantion or other agents can’t be used
Fosfomycin
What are the main causative organisms of cellulitis ?
Staph aureus, group A & other beta-haemolytic streptococci
What is the main causative organism of acute diabetic foot infections ?
Staph. aureus
What is the main causative organisms of, Diabetic foot acute on chronic polymicrobial, infections?
Staph aureus, coliforms & anaerobes
For skin and soft tissue infections flucloxacillin will cover what ?
beta-haemolytic streptococci (A C &G); so penicillin is not required in addition
For skin and soft tissue infections doxycycline will cover what ?
most Staph aureus (including MRSA) & beta-haemolytic streptococci
For skin and soft tissue infections co-trimoxazole will cover what?
67% of coliforms and 98% of Staph aureus (including MRSA)
What is the guidelines for taking samples from skin and soft tissue infections ?
- If severe or systemic infection take blood cultures.
- Swab wounds having removed superficial debris.
- Flora on surface of wound may be different to that causing infection. ==> Wound swabs cannot distinguish between infection and colonisation.
- Previous exposure to antibiotics may select out coliforms and Pseudomonas in particular. Colonisation does not need or respond to antibiotic treatment.
What is the main causative organism of septic arthritis/osteomyelitis ?
Staph. aureus
When investigating/treating septic arthritis/osteomyelitis what should you do?
Send blood cultures (before antibiotics where possible), joint aspirates/washouts & bone samples. Consider any distant foci of infection
What is important to remember just as in endocarditis treatment for the treatment of septic arthritis/ osteomyelitis ?
- Need high doses (iv)
- prolonged duration (4-6 weeks)
- bactericidal (killing rather than slowing growth) to penetrate joint and tissue, eliminate bacteraemia & reduce risk of septic emboli
Gram negative ‘coliforms’ (eg E coli, Klebsiella, Enterobacter, Proteus) & Pseudomonas aeruginosa are sensitive to what?
Gentmamicin and most to azteornam
Extended Spectrum Beta Lactamases (ESBL) are resistant to what?
most penicillins (including co-amoxiclav, piperacillin-tazobactam & aztreonam)
What antibiotics have cover for ESBL’s ?
Temocillin, pivmecillinam (& meropenem)
What do Temocillin & ertapenem not cover ?
Pseudomonas
why is metronidazole not needed when using Pip-tazobactam, co-amoxiclav (& meropenem)?
Because they have anaerobic cover
What does Temocillin & aztreonam not cover ?
Thye have no anaerobic or gram positive cover
Carbapenemase producing enterobacteriacae (CPE) are resistant to what?
penicillins, cephalosporins, pip-tazobactam, aztreonam, temocillin, carbapenems & often other classes of antibiotics – gentamicin, ciprofloxacin, co-trimoxazole
Early detection (screening/single room of those having healthcare from outside Scotland & screening patients form other Scottish hospitals), strict adherence to standard & transmission based infection control precautions & prudent prescribing including of meropenem must be in place to reduce impact of spread of these virtually untreatable bacteria.
Anaerobes are generally sensitive to what?
metronidazole (and co-amoxiclav, clindamycin, pip-tazobactam & meropenem)
Gram positives like Staph aureus (MSSA, MRSA), streps & enterococci are sensitive to vancomycin (except VREs): when is vanocymycin used ?
use restricted to penicillin allergy or penicillin resistant strains
MRSA is resistant to what?
All beta-lactams (penicillins, flucloxacillin, pip-tazobactam, cephalosporins & meropenem)
VRE are resistant to what?
vancomycin & meropenem
Beta-haemolytic streps (groups A C G) are sensitive to what?
Penicillin & flucloxacillin
