High carriage of plasmid-mediated quinolone resistance (PMQR) genes by ESBL-producing and fluoroquinolone-resistant Escherichia coli recovered from animal waste dumps.

BACKGROUND: There has been a rise in the consumption of fluoroquinolones in human and veterinary medicine recently. This has contributed to the rising incidence of quinolone resistance in bacteria. This study aimed at the determination of the antibiotic resistance profile of ESBL-producing and fluoroquinolone-resistant E. coli (FQEC) isolated from animal waste obtained from the waste dumps of an agricultural farm and their carriage of genes encoding PMQR. METHODS AND RESULTS: Isolation of ESBL-producing E. coli from animal waste samples was done on CHROMagar ESBL, while presumptive isolates were purified, and identified via the detection of uidA gene. Susceptibility to a panel of ten antibiotics was done using the disc diffusion method, and detection of PMQR genes (qnrA, qnrB, qnrS, aac(6')-lb-cr, qepA and oqxAB) was done using monoplex and duplex PCR. Twenty-five ESBL-producing and FQEC were obtained from the cattle (6), piggery (7) and poultry (12) waste dumps of the farm. There was 100% resistance to cefpodoxime, cefotaxime, enrofloxacin, trimethoprim-sulfamethoxazole and penicillin by the isolates. The resistance to the other antibiotics was streptomycin (48%), ceftazidime (24%), while no isolate resisted amoxicillin-clavulanate and imipenem. The frequencies of PMQR genes detected were; qnrA (96%), oqxAB (96%), qnrB (92%), while  qnrS was detected in 88% (22) of the isolates. Aminoglycoside acetyltransferase (aac(6')-lb-cr) and quinolone efflux pump (qepA) were each detected in 20 (80%) of the isolates. CONCLUSIONS: This study showed that animal wastes disposed indiscriminately into dumps could be a budding 'hotspot' for multidrug resistant, ESBL-producing and fluoroquinolone-resistant E. coli carrying multiple genes encoding resistance to fluoroquinolone antibiotics.

High burden of ESBL- producing Klebsiella spp., Proteus mirabilis, Enterobacter cloacae and Pseudomonas aeruginosa in diagnosed cases of urinary tract infection in a Nigerian Teaching Hospital.

Infections of the urinary tract have been on the rise globally and these are also worsened by the increasing rate of antibiotic resistance in uropathogens. This study aimed to determine the susceptibility profile of extended spectrum ß-lactamase (ESBL)- producing uropathogens to selected antibiotics and their carriage of ESBL genes. Bacterial uropathogens were obtained from the urine bench of a Microbiology laboratory in a Teaching Hospital in South-West Nigeria. Susceptibility to antibiotics was tested using the disc diffusion method, while detection of ESBL production was done using the double disc synergy test (DDST). Detection of ESBL genes was performed by PCR. A total of 21 ESBL- producing uropathogens were obtained namely: Klebsiella pneumoniae (11), Klebsiella oxytoca (6), Proteus mirabilis (2), Enterobacter cloacae (1) and Pseudomonas aeruginosa (1). The resistance to antibiotics in the uropathogens was: imipenem (0%), gentamicin (38.1%), sulfamethoxazole-trimethoprim (52.4%), amoxicillin-clavulanate (61.9%), aztreonam (66.7%), ceftazidime (66.7%), tetracycline (90.5%), cefpodoxime (100%) and cefotaxime (100%). Altogether, 90.5% (19/21) of the isolates were multidrug resistant (MDR). Of the 21 uropathogens, 61.9% (13/21) carried bla CTX-M, 52.4% (11/21) carried bla TEM while bla SHV was detected in 47.6% (10/21) of the isolates. There was co-carriage of ESBL genes in 12 uropathogens. This study showed a high prevalence of multidrug resistance and a high carriage of ESBL genes in the ESBL- producing isolates obtained over the study period. There is a need for a review of antibiotic options in the treatment of UTI to clamp down on the ever-increasing tide of antibiotic resistance in uropathogens.

High carriage of plasmid-mediated quinolone resistance (PMQR) genes by cefotaxime-resistant Escherichia coli recovered from surface-leaking sanitary sewers.

There is a rapid rise in the incidence of quinolone resistant bacteria in Nigeria. Most studies in Nigeria have focused on isolates from the clinical settings, with few focusing on isolates of environmental origin. This study aimed to investigate the antibiogram and carriage of plasmid-mediated quinolone resistance (PMQR) genes by quinolone-resistant isolates obtained from a pool of cefotaxime-resistant Escherichia coli (E. coli) recovered from sewage leaking out of some surface-leaking sanitary sewers in a University community in Nigeria. Isolation of E. coli from the sewage samples was done on CHROMagar E. coli, after enrichment of the samples was done in Brain Heart Infusion broth amended with 6 µg/mL of cefotaxime. Identification of presumptive E. coli was done using molecular methods (detection of uidA gene), while susceptibility to antibiotics was carried out using the disc diffusion method. Detection of PMQR genes (qnrA, qnrB, qnrS, aac(6')-lb-cr, qepA and oqxAB) was carried out using primer-specific PCR. A total of 32 non-repetitive cefotaxime-resistant E. coli were obtained from the sewage, with 21 being quinolone-resistant. The quinolone-resistant isolates showed varying level of resistance to the tested antibiotics, with imipenem being the only exception with 0% resistance. The PMQR genes: aac(6')-lb-cr, qnrA, qnrB, qnrS and qepA and oqxAB were detected in 90.5%, 61.9%, 47.6%, 38.1%, 4.8% and 0% respectively of the isolates. The findings of this study showed a high level of resistance to antibiotics and carriage of PMQR genes by quinolone-resistant E. coli obtained from the leaking sanitary sewers, suggesting a potential environmental and public health concern.