ESBL-Positive Enterobacteria Isolates in Drinking Water

To the Editor: Extended-spectrum β-lactamase (ESBL)– producing members of the family Enterobacteriaceae (enterobacteria) are a worldwide problem (1), but little data are available from central Africa (2). In recent years, ESBL-producing Enterobacteriaceae isolates have shifted from the hospital to the community and the environment (1). The aim of this study was to assess the presence of ESBL-producing Enterobacteriaceae isolates in sachet-packaged water bags sold as drinking water in the streets of Kinshasa, the capital of Democratic Republic of the Congo. In November 2009 and June 2010, a total of 101 sachet-packaged water bags were bought from street vendors in 9 of 24 municipalities (covering residential areas and slums) of the city of Kinshasa. The bags were transported in ice coolers and processed within 4 hours of collection. We fi ltered 100 mL of each sample through 0.45-μm pore size fi lters (Sartorius, Goettingen, Germany). The fi lters were then transferred to an agar plate containing mEndoLES agar (Difco, Franklin Lakes, NJ, USA) and incubated at 35°C for 24 hours. Growing colonies were subcultured on Kligler iron agar (Oxoid, Cambridge, UK), and gram-negative glucose-fermenting isolates were identifi ed to the species level and assessed for antimicrobial drug susceptibility with Microscan NBC42 panels). Isolates labeled by Microscan as ESBL producers were confi rmed by the double-disk method, which compared 1 disk containing cefotaxime with 1 disk containing cefotaxime and clavulanic acid and 1 disk containing ceftazidime with 1 disk containing ceftazidime and clavulanic acid (Rosco Diagnostica, Taastrup, Denmark), according to the Clinical and Laboratory Standards Institute guidelines (3). We used Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 700603 as control strains. Detection and identifi cation of ESBL-producing bla genes were carried out by using a commercial multiplex ligation PCR microarray CT 101 (CheckPoints Health BV, Wageningen, the Netherlands) (4). A total of 101 sachet-packaged water bags were purchased at random from different vendors: 88 sealed and branded bags (of 68 different brands) and 13 hand-tied unbranded bags. The precise origin of the water could not be determined because vendors are unlicensed resellers and most producers are not registered. Water bags lacked essential information such as contact addresses, batch number, and production and expiration dates. Because we also observed empty branded sheets of bags for sale on the market, we assumed that many of the branded bags are simply fi lled with tap water or water from other supplies without any prior …