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. 2019 May 21;1(1):dlz015. doi: 10.1093/jacamr/dlz015

Table 1.

Characteristics of various antibiotics on the WHO Essential Medicines List,38 characterized by administration route and CDI risk

Antibiotic Oral bioavailability/absorption (and excretion) Excretion (including biliary/faecal) following iv administration CDI risk (data from NICE evidence summary comprising three meta-analysesa)39
Amikacin NA Renal excretion. Low biliary tract concentrations versus serum.40

  1. aminoglycosides: no significant association seen

  2. not assessed

  3. not assessed
Amoxicillin ∼70% bioavailable.41 Predominantly renal. Detected in biliary system following iv administration, but lower concentrations compared with serum.41,42

  1. penicillins: no significant association seen (note subgroup analysis below)

  2. penicillins: 5 studies: OR 2.71 (95% CI 1.75–4.21)

  3. penicillins: 4 studies: OR 3.25 (95% CI 1.89–5.57)
Amoxicillin/ clavulanic acid See above. See above. Clavulanic acid excreted in urine, bile and faeces.43

  1. subgroup analysis; penicillin combination antibiotics (e.g. co-amoxiclav and piperacillin/tazobactam): 6 studies: OR 1.54 (95% CI 1.05–2.24)

  2. penicillins: 5 studies: OR 2.71 (95% CI 1.75–4.21)

  3. penicillins: 4 studies: OR 3.25 (95% CI 1.89–5.57)
Azithromycin 37% plasma bioavailability due to high tissue binding (rather than low GI absorption). Biliary excretion is a major route of elimination.44 NA

  1. macrolides: no significant association seen

  2. macrolides: 4 studies: OR 2.65 (95% CI 1.92–3.64)

  3. macrolides: 3 studies: OR 2.55 (95% CI 1.91–3.39)
Benzylpenicillin NA Predominantly renal (60%–90%). Biliary excretion is only a minor fraction.45

  1. see amoxicillin

  2. see amoxicillin

  3. see amoxicillin
Cefalexin High.46 Low biliary excretion; predominantly renal.40,46

  1. subgroup: first-generation cephalosporins, no significant association seen: OR 1.36 (95% CI 0.92–2.00)

  2. cephalosporins: 5 studies: OR 5.68 (95% CI 2.12–15.23) (also includes monobactams and carbapenems)

  3. cephalosporins: 3 studies: OR 4.47 (95% CI 1.60–12.50)
Cefixime Low (22%–54%); excreted predominantly unchanged in urine.47 NA

  1. subgroup: third-generation cephalosporins, 6 studies: OR 3.20 (95% CI 1.80–5.71)

  2. see cefalexin

  3. see cefalexin
Cefotaxime NA Predominantly renal, but high concentrations in bile.40,48,49

  1. see cefixime

  2. see cefixime

  3. see cefixime
Ceftriaxone NA High unchanged biliary excretion (∼40%–50%).40,50

  1. see cefixime

  2. see cefixime

  3. see cefixime
Chloramphenicol NA Mostly renal excretion; low active concentrations in bile.40

  1. not assessed

  2. not assessed

  3. not assessed
Ciprofloxacin 70%–80% absolute bioavailability.51 Predominantly renal; 15% via faeces after iv (mainly intestinal secretion); 1% bile.51,52

  1. quinolones: 10 studies: OR  1.66 (95% CI  1.17–2.35)

  2. quinolones: 5 studies: OR 5.50 (95% CI 4.26–7.11)

  3. quinolones: 3 studies: OR 5.65 (95% CI 4.38–7.28)
Clarithromycin High GI absorption. ∼50% absolute oral bioavailability after 250 mg dose after first-pass metabolism.53 20%–40% excreted unchanged in urine (increases with dose increase). 10%–15% in urine as metabolite. Rest is excreted in faeces.53

  1. see azithromycin

  2. see azithromycin

  3. see azithromycin
Clindamycin High concentrations in bile. 90% plasma binding. Over 90% absorption orally (absolute bioavailability 53% ± 14% for 600 mg dose).54 10% of the active drug/metabolites are excreted in the urine, 4% in the faeces; remainder is excreted as inactive metabolites (predominantly faecally).54

  1. 6 studies: OR 2.86 (95% CI   2.04–4.02)

  2. 3 studies: OR 16.80 (95% CI 7.48–37.76)

  3. 2 studies: OR 20.43 (95% CI 8.50–49.09)
Doxycycline 93%, almost all absorbed in upper GI tract. Concentrated in bile. 40% of the dose is eliminated in active form in the urine, and 32% in the faeces, after 3 days. High urinary concentrations achieved but in the presence of renal impairment, urinary elimination decreases and faecal elimination increases.55 NA

  1. no significant association seen

  2. no significant association seen

  3. no significant association seen
(Flu)cloxacillin 79% oral absorption.56 Predominantly renal. 66% if oral, 76% if parenteral, active drug in urine. Small amount in bile.56

  1. see amoxicillin

  2. see amoxicillin

  3. see amoxicillin
Gentamicin NA Renal excretion. Low bile secretion.40 Shown to have therapeutic concentrations in bile with once daily dosing.57,58

  1. see amikacin

  2. see amikacin

  3. see amikacin
Meropenem NA Penetrates biliary tract well.40,59 70% excreted within 12 h unchanged in urine; 2% faecal.59

  1. 6 studies: OR 1.84 (95% CI  1.26–2.68)

  2. see cefalexin: assessed with cephalosporins and monobactams

  3. not assessed
Metronidazole Almost complete oral absorption.60 50% in urine in active form and metabolites. 20% in faeces.61

  1. not separately assessed

  2. not separately assessed

  3. not separately assessed
Nitrofurantoin Rapidly absorbed in upper GI tract but low serum levels.62 Urinary excretion.62

  1. not separately assessed

  2. not separately assessed

  3. not separately assessed
Phenoxymethylpenicillin ∼60% absorbed.63 Renal excretion. Small amount in bile.63

  1. see benzylpenicillin

  2. see benzylpenicillin

  3. see benzylpenicillin
Piperacillin/tazobactam NA High concentrations in bile and 20% biliary excretion.40

  1. see amoxicillin/clavulanic acid

  2. see amoxicillin/clavulanic acid

  3. see amoxicillin/clavulanic acid
Sulfamethoxazole/ trimethoprim Almost 100% absorption.65 Predominantly renal.64

  1. 5 studies: OR   1.78 (95% CI  1.04–3.05)

  2. 4 studies: OR 1.81 (95% CI 1.34–2.43)

  3. 3 studies: OR 1.84 (95% CI 1.48–2.29)
Vancomycin Not usually absorbed in the blood after oral administration (unless bowel wall injury is present, e.g. pseudomembranous colitis).65 Parenteral: predominantly renal, with only 5% biliary. Oral: very low in urine. High concentrations in faeces.65

  1. not separately assessed

  2. not separately assessed

  3. not separately assessed

GI, gastrointestinal; NA, not applicable.

a

NICE evidence summary of CDI risk with broad-spectrum antibiotics. Compiled data from three meta-analyses: (i) Slimings and Riley (2014)89 reviewed hospital-associated CDI; (ii) Brown et al. (2013)90 reviewed community-associated CDI; and (iii) Deshpande et al. (2013)75 reviewed community-associated CDI.