antibiotics Flashcards
eTG treatment regimen for empirical treatment of suspected infective endocarditis
benzylpenicillin 1.8g iv Q4h \+ flucloxacillin 2g iv Q4h \+ gentamicin iv over 3-5 minutes
eTG empirical therapy for meningitis
- ceftriaxone 2g iv Q12h OR cefotaxime 2g iv Q6h
- anaphylaxis to penicillins: use moxifloxacin 400mg iv daily
maybe 2. benzylpenicillin 2.4g Q4h (if suspecting Listeria monocytogenes, which is intrinsically resistant to cephalosporins) *suspect in patients older than 50 years, immunocompromised, pregnant or debilitated, those with hazardous ETOH consumption
2nd line: if benpen hypersensitive, use TMP-SMX 5+25mg/kg up to 480+2400mg iv Q8h
maybe 3. add vancomycin if G+ diplococci are seen / if pneumococcal antigen assay of CSF is positive / or if pt has known or suspected otitis media or sinusitis / or recently treated with a beta-lactam in case of strep pneumoniae resistance / or if G+ resembling staph / or if LP is contra-indicated
25-30mg/kg iv loading dose
*practically good to administer after cephalosporin due to long infusion time required
directed therapy for meningitis
1 Neisseria meningitidis ‘meningococcal’
- ceftriaxone 2g iv Q12h for 5/7 OR cefotaxime 2g iv Q6h for 5/7
In penicillin hypersensitivity: use ciprofloxacin 400mg iv Q8h for 5/7 - stop dexamethasone therapy
- if only benpen was used, won’t clear nasopharyngeal carriage: requires abx clearance of pt and close contacts. Options are:
- ciprofloxacin 500mg oral as a single dose
- ceftriaxone 250mg IM as a single dose (preferred in pregnant women)
- rifampicin 600mg oral, Q12h for 2 days (preferred in neonates) *contra-indicated in pregnancy and severe liver disease
First, determine MIC of penicillin, ceftriaxone and cefotaxime; MIC <0.125mg/L means it can be treated with penicillins
- benzylpenicillin 2.4g iv Q4h for 10-14 days
For strains penicillin resistant (MIC =/> than 0.125mg/L) but ceftriaxone/cefotaxime susceptible (MIC < 1.0mg/L) use:
1: ceftriaxone 2g iv Q12h for 10-14 days OR cefotaxime 2g iv Q6h for 10-14 days
For strains pen res (MIC =/> 0.125mg/L) and ceftriaxone or cefotaxime (MIC 1.0-2.0 mg/L):
- add moxifloxacin or vancomycin to ceftriaxone or cefotaxime:
moxifloxacin 400mg iv daily for 10-14 days OR vancomycin iv for 10-14 days
If MIC of ceftriaxone or cefotaxime is >2.0mg/L: moxifloxacin 400mg iv daily for 10-14 days
Use ceftriaxone 2g iv Q12h for 7/7 OR cefotaxime 2g iv Q6h for 7/7
If then susceptibility to benpen is confirmed and not pen hypersensitive use:
- de-escalate therapy to benpen 2.4g iv Q4h for 7/7. For immediate hypersensitive patients use:
ciprofloxacin 400mg iv Q8h 7/7
then if under 5 years, give catch-up Hib vaccines once recovered
if they weren’t treated with ceftriaxone/cefotaxime/ciprofloxacin, then give:
rifampicin 600mg oral daily for 4/7. If rifampicin is contra-indicated (pregnancy, severe liver disease), give ceftriaxone 1g IM or IV daily for 2/7
1: benzylpenicillin 2.4g iv Q4h
second line (if pen hypersensitive):
- TMP-SMX 5+25mg/kg up to 480+2400mg iv Q8h
Duration of therapy: 3/52, 6/52 in immunocompromised. For treatment beyond 3/52, as long as no clinical features of infection remain and they can tolerate it, they can go on TMP-SMX (adult more than 60 kg: 320+1600 mg; adult 40 to 60 kg: 240+1200 mg; child 1 month or older: 6+30 mg/kg up to 240+1200 mg) orally, 12-hourly
Cease dexamethasone
#5 Streptococcus agalactiae (Group B strep meningitis epi: most common cause of meningitis in neonates, occasional in adults benzylpenicillin 2.4 g (child: 60 mg/kg up to 2.4 g) intravenously, 4-hourly for at least 14 days; extend to 21 days for complicated infection. *check dosing for neonates
- cause of acute bacterial meningitis especially in SE Asia
- treat like strep pneumoniae but ensure dexamethasone is given early (before or with first abx dose) to reduce risk of severe hearing loss
- gram-negative rods
- iatrogenic entry e.g. neurosurgery, trauma, ventricular shunts
*inc WCC on CSF in absence of clinical features of bacterial infection is not convincing
1st: vancomycin 25-30mg/kg iv loading dose
+
ceftazidime 2g iv q8h OR cefepime 2g iv Q8h
If culture positive, duration of treatment is 10-21 days:
shorter duration if: coagulase-negative staphylococci or Cutibacterium acnes (formerly Proprionibacterium acnes) / if few systemic symptoms / if minimal CSF pleiocytosis or normal CSF glucose concentrations
If CSF cultures are negative after 5-7 days, stop abx and monitor pt
With repeat CSF +ve cultures despite appropriate abx therapy, continue treatment for 10-14 days after the last positive BC
If ongoing, remove the device, consider intraventricular abx
- sub-acute, chronic illness of headaches, fever and altered mental state
caused by Cryptococcus gattii (immunocompetent) OR cryptococcus neoformans (immunocompromised). Can cause mass lesions in the brain ‘cryptococcomas’. Suspect undiagnosed HIV
May need repeat LP for off-loading CSF as can get high pressures which can cause vision and hearing loss. e.g. in pts with recurrent headaches, new seizures, symptoms and signs of raised ICP, or documented high opening pressures.
Drug therapy:
phases: induction, consolidation, eradication (or suppression for those who are persistently immunocompromised)
Induction therapy (2-6/52 duration, depending on culture conversion, presence of cryptococcomas, whether the pt is immunocompromised, and the species of Cryptococcus ), use:
- amphotericin B liposomal 3-4mg/kg iv daily OR amphotericin B lipid complex 5mg/kg iv daily OR amphotericin B desoxycholate 0.7-1 mg/kg iv daily
PLUS
flucytosine 25mg/kg oral Q6h *monitor plasma conc. and FBE for bone marrow suppression OR if oral therapy is not tolerated: flucytosine 25mg/kg iv Q6h.
alternative therapies are:
amphotericin w/o flucytosine and high-dose fluconazole w or w/o flucytosine
For consolidation and eradication therapy,
fluconazole: 400-800mg oral daily.
*fluconazole can cause nausea at high doses. A dose of 400mg daily is suitable for most patients
Higher doses may be required in heavier patients and when induction therapy cannot be completed.
For consolidation phase: 400-800mg daily (induction + consolidation phase duration of treatment should be at least 10 weeks)
for eradication phase: 200-400mg daily
*expert advice if fluconazole resistant.
total duration is 12-18 months depending on whether patient remains immunocompromised, and resolution of cerebral cryptococcomas
refer to eTG if patient is being treated for HIV: eradication therapy needs to continue for at least 1 year and until CD4 count is more than 100 cells/microlitre for =/>3 months
- vancomycin 25-30mg/kg loading PLUS
- ceftazadime 2g iv Q8h OR cefepime 2g iv Q8h
- usually caused by Angiostrongylus cantonensis, sometimes by Gnathostoma species
- confirm eosinophils on CSF by Giemsa strain: standard CSF stains can’t distinguish between eosinophils and neutrophils
Angiostrongylus cantonensis:
from eating snails and slugs in eastern Australia
steroids improve symptoms
benefits of antihelminth treatment with steroids is thought to be of benefit if started within 3 weeks of exposure
Recurrent benign lymphocytic meningitis
caused by HSV type II (‘Mollaret meningitis’) from eTG however, anecdotal experience suggests valaciclovir or famciclovir may be helpful as episodic or suppressive therapy in patients with frequent confirmed recurrences.
eTG treatment of brain abscess and subdural empyema
Causes:
in immunocompetent:
- polymicrobial: microaerophilic cocci including strep anginosus (milleri) group (this and s. constellatus and s. intermedius) and anaerobic bacteria
- ear infection: gram-negative bacilli
- after trauma or surgery, often staph aureus
- in immunocompromised: Nocardia spp, toxoplasma gondii and fungi such as Cryptococcus species, Aspergillus spp, or Scedosporium spp are more likely
Management:
- surgical opinion for MCS sample and drainage
- ceftriaxone 2g iv Q12h OR cefotaxime 2g iv Q6h PLUS metronidazole 500mg iv Q8h
For those with inc. risk of MRSA:
- give vancomycin iv
for brain abscess after surgery,
- give vancomyin iv PLUS ceftazidime 2g iv Q8h or cefepime 2g iv Q8h
Ongoing management:
usually 4-8 weeks, with minimum of 2/52 of iv treatment
Oral treatments with appropriate penetration need to be used: TMP-SMX, moxifloxacin)
*beta-lactams have poor oral bioavailability and poor BBB penetration
treatment of GI infections
- abx not indicated for community diarrhoea
- abx not indicated for child with bloody diarrhoea without fever or sepsis
- obtain faecal MCS before starting
Treatment:
1. ciprofloxacin 500mg oral, Q12h for 3 days OR norfloxacin 400mg oral, Q12h for 3 days
If disease likely acquired in area with quinolone resistance e.g. SE Asia or oral suspension is required, consider:
azithromycin 500mg oral daily for 3/7
If oral therapy is not tolerated or absorption is likely to be impaired, consider:
ceftriaxone 2g iv daily for 3 days
Treatment of serratia
Aminoglycoside + anti-pseudomonal beta lactam e.g 4th generation cephalosporin
bugs where lines need to be removed
s aureus, candidaemia, sometimes pseudomonas
treating campylobacter causing diarrhoea
gram negative rods, similar to vibrio
from: unpasteurised milk, contaminated poultry or water, contact with contaminated pets or farm animals
fever, stomach cramps, bloody diarrhoea
complications: GBS, meningitis, UTI, sepsis, reactive arthritis
path: campylobacter stool specimen
treatment:
indicated in severe disease, pregnancy, immunocompromised, or the elderly
azithromycin 500mg daily for 3/7 OR
*ciprofloxacin 500mg BD for 3/7 OR
*norfloxacin 400mg BD for 3/7
*not for children - impact on cartilage development
clostridium difficile
risk factors:
- broad-spectrum antibiotic tx e.g. cephalosporins, lincosamides, quinolones; hospitalisations, chemotherapy, use of PPIs.
Dx:
- micro evidence of toxin-producing C. difficile in stools
- colonoscopy or histology findings consistent with pseudomembranous colitis
Testing indicated when:
- bloody diarrhoea, or prolonged symptoms
- immunocompromised
- in an outbreak setting
Ix:
NAAT -> PCR
then EIA
rifampicin side effects
N/V/D
hepatitis
red-orange discolouration of fluids, jaundice, dark urine, pale faeces
