Resistance to Antibiotics in Injured Coliforms Isolated from Drinking Water

Abstract

Abstract:We studied the antibiotic sensitivity of injured coliforms isolated from drinking water of La Plata, Argentina. The antibiotic sensitivity test by the agar diffusion method were proved in: Klebsiella oxytoca (14 strains), Enterobacter aerogenes (4 strains) and Enterobacter cloacae genomic group 3 (14 strains). We found that while these impaired total coliforms were sensitive to piperacillin-tazobactam (TAZ), netilmicin (NTL), ofloxacin (OFLX), and norfloxacin (NFLX) (100%), they had resistant to aminopenicillin-sulbactam (AMS) and nitrofurantoin (NIT) (100%). The resistance to antibiotics demonstrated in these strains would point to the need to promote a rational and judicious use of antimicrobial agents while at the same time implementing a program of active vigilance aimed at ensuring the highest quality of drinking water throughout the system. Key words: Injured coliforms, Water, Antibiotics, ResistanceThe microbiological quality of water destined for human consumption is evaluated in an indirect fashion by screening for the presence of so-called indicators of fecal contamination. Accordingly, during more than the last 80 years the coliform bacterial group has been employed in this way for the assessment of the sanitary quality of drinking water. Nevertheless, the failure to detect the presence of these indicator organisms constitutes an insufficient criterion for concluding that a sample of water is bacteriologically pure since these same coliforms, when injured, may show up as negative in the conventional assays normally employed while still remaining potentially viable. Such sublethal modifications in the bacterial phenotype are thought to arise as the result of environmental influences of both a biotic and an abiotic nature and can furthermore be accompanied by alterations in the wild-type pattern of susceptibility to antimicrobial agents. In this regard, although antibioticresistant strains of enterobacteria have been found in aquatic surroundings in the wild and in wastewater (7,10,14), little is known regarding the prevalence of injured Through the use of m-T7 agar, especially formulated for the rescue of impaired bacteria, we isolated injured coliforms from the drinking-water distribution network of La Plata (l). These isolates, once identified, proved to be of the following species: Klebsiella oxytoca [14 strains], Enterobacter aerogenes [4 strains] and E. cloacae genomic group 3 [14 strains]. The objective of the current work was to study the antibiotic sensitivity of the injured enterobacteria within the public water supply in La Plata city, Buenos Aires, Argentina.For the isolation of injured coliforms from drinkingwater samples, we employed the membrane-filtration technique (2) and at the same time measured the pH and free-chlorine concentration of each specimen. With water derived from each source throughout the city, the

Occurrence of antimicrobial-resistant Enterobacteriaceae in water from different sources in a subtropical region of Argentina

“…Even when only one ampicillin-resistant Escherichia coli strain was isolated from drinking water in our work, other authors from Germany (Schwartz et al, 2003) and from Argentina (Córdoba et al, 2001) have found many strains resistant to several antibiotics in the same kind of samples.…”

“…The presence of several antibiotic compounds in both sewage treatment plants effluents and surface waters result most likely from applications in human medicine than from veterinary uses (Hirsch et al, 1999). Added to this fact, bacteria with acquired resistance have been also found in surface water, ground water, and drinking water in different countries (McKeon et al, 1995;Schwartz et al, 2003;Córdoba et al, 2001).…”

“…Enterobacteriaceae members are broadly distributed in the environment and they are etiological agents of a great number of infectious diseases (Schreckenberger et al, 1999). Antimicrobial-resistant enterobacteria have been isolated from a variety of sources (Boon et al, 1999;Córdoba et al, 2001;Sayah et al, 2005), but up to now there is not any data about this topic in a subtropical area characterized by a great diversity of aquatic ecosystems.…”

Influencing factors in the occurrence of injured coliforms in the drinking water distribution system in the city of La Plata, Argentina

“…The regrowth of these species can decrease water quality and generate public health problems Có rdoba et al 2001).…”

Injured coliforms in swimming pools : How big a threat?

“…Pathogenic bacteria may be more resistant than indicator bacteria to chlorine and may even overgrow indicator bacteria, creating a veiled threat [8] . Moreover, a previous study revealed that injured bacteria can also harbor antimicrobial resistance [9] .…”