Multiresistance, beta-lactamase-encoding genes and bacterial diversity in hospital wastewater in Rio de Janeiro, Brazil.

AIMS: To investigate the bacterial diversity, antimicrobial resistance patterns and types of beta-lactamase genes in Gram-negative bacteria isolated from a hospital sewage treatment plant. METHODS AND RESULTS: Between July and December 2008, we collected samples from influent, clarifier tank effluent and chlorine contact tank effluent from a sewage treatment plant service of a hospital located in the city of Rio de Janeiro, Brazil. Of the 221 isolates identified, 40% were characterized as extended-spectrum beta-lactamase (ESBL) producers. Nonpathogenic micro-organisms and some pathogenic genera were quantified. The most common ESBL-producing isolates were Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli. The bla(TEM), bla(SHV) and bla(CTX-M) genes were detected in 82, 48 and 67% of bacterial isolates, respectively. CONCLUSIONS: Results showed that hospital wastewater treatment plant is not suitable systems for the removal of all antibiotic-resistant micro-organisms present in hospital wastewaters. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides evidence that bacteria resistant to multiple antibiotics and their resistance genes that are usually present in the hospital can reach the environment, even after the use of hospital wastewater treatment plants.

Detection of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in effluents and sludge of a hospital sewage treatment plant.

AIMS: To detect ESBL (extended-spectrum beta-lactamase)-producing Klebsiella pneumoniae present in the effluents and sludge of a hospital sewage treatment plant, evaluating the treatment plant's potential to remove these micro-organisms. METHODS AND RESULTS: Twenty samples (crude sewage, UASB reactor effluent, filtered effluent and sludge) were collected in the period from May to December 2006, in order to analyse antimicrobial susceptibility and to check ESBL production, the disc-diffusion and the combined disc methods were used. Total and faecal coliform concentrations were also determined. ESBL-producing K. pneumoniae were detected in all samples analysed, representing 46 x 5% of the total strains isolated. Among the non-ESBL-producing strains, 26% were multiresistant and one strain resistant to eight of the nine antimicrobials tested was detected in the treated effluent. CONCLUSIONS: The hospital wastewater treatment plant did not show a satisfactory efficacy in removing pathogenic micro-organisms, allowing for the dissemination of multiresistant bacteria into the environment. SIGNIFICANCE AND IMPACT OF THE STUDY: The inefficacy of hospital wastewater treatment plants can result in routes of dissemination of multiresistant bacteria and their genes of resistance into the environment, thus contaminating water resources, and having serious negative impact on public health.

Evaluation of a RAPD-based typing scheme in a molecular epidemiology study of Vibrio cholerae O1, Brazil.

AIMS: To evaluate the utility of random amplification of polymorphic DNA (RAPD) technique for routine practice in public health laboratories for epidemiological studies of Vibrio cholerae O1 isolates. MATERIALS AND RESULTS: Seventy-nine strains were examined by PCR for the toxin genes (ctx A, zot and ace), virulence-associated genes (tcp A and tox T) and RAPD sequences. Except for one strain (no. 1123) from the Amazonas State, all the strains analysed carried the genes ctx A, zot, ace, tcp A and tox T. RAPD fingerprinting revealed variability but no correlation with serotype, biotype or geographical origin of the isolates was found. CONCLUSION: A standardized RAPD method does not enable the establishment of a pattern data bank for the identification of V. cholerae O1 strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The simplicity and discriminative capacity of this technique make it useful for detecting genetic diversity among micro-organisms from a defined group or for outbreak investigation.

[The emergence of multiple antimicrobial resistance in Vibrio cholerae isolated from gastroenteritis patients in Ceará, Brazil]. / Emergência da múltipla resistência a antimicrobianos em Vibrio cholerae isolados de pacientes com gastroenterite no Ceará, Brasil.

Of 7058 Vibrio cholerae strains recovered from patients suspected of cholera in the State of Ceará between December 1991 and September 1993, two were resistant to antimicrobials (Ampicillin, erythromycin, trimethoprim-sulfamethoxazole, tetracycline) and to vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine). From the bacteriological standpoint, one strain was identified as V. cholerae serogroup O:1, biotype El Tor, serovar Inaba, and another as V. cholerae serogroup O:22, biochemically classified as Heiberg type II. It was shown that only in the serogroup O:1 strain, multiple resistance was encoded by a plasmid transferrable by conjugation to Escherichia coli K12 and a sensitive strains of V. cholerae O1 and non-O1, with at a frequency between 8 x 10(-2) and 5 x 10(-6). The plasmid, with a molecular weight of 147 Kb, encoded both multiple resistance to antimicrobials and the vibriostatic compound (O/129), compatible with descriptions reported in other parts of world.