Surveillance of antibiotic resistance in urinary coliforms in Greater Lincolnshire, U.K. and the potential for temocillin, ertapenem and mecillinam usage

Abstract number: P678

Vicca A.F., Cowling P., Brightman C.A.J., Youngs E.R., Stoddart B., Loudon K.W.

Objective: Surveillance of antibiotic sensitivity patterns in resistant urinary coliforms for a large, rural population over a recent six month period.

Method: Lincolnshire is England's second largest county with an area of >500 hectares and a largely rural population of >1 million. It is covered by a single-managed microbiology service which uses U.K. Health Protection Agency national standard operating procedures, disc diffusion sensitivity testing to BSAC standards and collects sensitivity data on one IT database. This was interrogated for all urinary coliforms from hospital and community patients that required second line sensitivity testing over the period of March to August 2008 and sensitivities of these isolates to 16 routinely tested antibiotics were recorded.

Results: Of 16,944 urinary coliform isolates from hospitals and community tested March-August 2008, 806 (4.8%) were multi-resistant requiring second line sensitivity tests. Percentage sensitivities against 16 antibiotics are shown in the figure (AMC = amoxicillin clavulanate; AMX = amoxicillin; ATM = aztreonam; CAZ = ceftazidime; CFX = cefalexin; CIP = ciprofloxacin; CPO = cefpodoxime; CTX = cefotaxime; CXM = cefuroxime; ERT = ertapenem; GEN = gentamicin; MEC = mecillinam; NIT = nitrofurantoin; TAZ = piperacillin-tazobactam; TEM = temocillin; TMP = trimethoprim). Sensitivity to temocillin, ertapenem and mecillinam was 95.8%, 95.4% and 83.6% for all multi-resistant isolates, 92.7%, 90.6% and 83.3% for all gentamicin resistant isolates (n = 96), 93.5%, 95.7% and 92.4% for all ciprofloxacin resistant isolates (n = 184). 108 (0.6% of total isolates, 13.4% of resistant isolates) were extended spectrum beta lactamase (ESBL) producers and 32 (0.2% of total, 4.0% of resistant) were Enterobacter, Citrobacter, Morganella, or Serratia genera. Sensitivities against these four genera and ESBLs were highest (>95%) for temocillin, ertapenem and mecillinam.

Number resistant coliforms tested

Conclusion: In our large, predominantly rural, population, temocillin and ertapenem show the lowest resistance rates of 16 antibiotics routinely tested in resistant urinary coliforms. For ESBL producers and Enterobacter, Citrobacter, Morganella, Serratia genera, temocillin, ertapenem and mecillinam have very low resistance rates. Mecillinam is available as an oral preparation but sensitivity testing in ESBLs may be unreliable. Temocillin and ertapenem are good options for the treatment of antibiotic multi-resistant urinary pathogens in hospital patients.