Characterization of Antibiotic Resistant Coliform Bacteria and Resistance Genes Isolated from Samples of Smoothie Drinks and Raw Milk

Multidrug-resistance and extended-spectrum beta-lactamase-producing lactose-fermenting enterobacteriaceae in the human-dairy interface in northwest Ethiopia

BACKGROUND

Antimicrobial resistance (AMR) is among the top public health concerns in the globe. Estimating the prevalence of multidrug resistance (MDR), MDR index (MDR-I) and extended-spectrum beta-lactamase (ESBL)-producing lactose fermenting Enterobacteriaceae (LFE) is important in designing strategies to combat AMR. Thus, this study was designed to determine the status of MDR, MDR-I and ESBL-producing LFE isolated from the human-dairy interface in the northwestern part of Ethiopia, where such information is lacking.

METHODOLOGY

A cross-sectional study was conducted from June 2022 to August 2023 by analyzing 362 samples consisting of raw pooled milk (58), milk container swabs (58), milker's hand swabs (58), farm sewage (57), milker's stool (47), and cow's feces (84). The samples were analyzed using standard bacteriological methods. The antimicrobial susceptibility patterns and ESBL production ability of the LFE isolates were screened using the Kirby-Bauer disk diffusion method, and candidate isolates passing the screening criteria were phenotypically confirmed by using cefotaxime (30 μg) and cefotaxime /clavulanic acid (30 μg/10 μg) combined-disk diffusion test. The isolates were further characterized genotypically using multiplex polymerase chain reaction targeting the three ESBL-encoding- genes namely blaTEM, blaSHV, and blaCTX-M.

RESULTS

A total of 375 bacterial isolates were identified and the proportion of MDR and ESBL-producing bacterial isolates were 70.7 and 21.3%, respectively. The MDR-I varied from 0.0 to 0.81 with an average of 0.30. The ESBL production was detected in all sample types. Genotypically, the majority of the isolates (97.5%), which were positive on the phenotypic test, were carrying one or more of the three genes.

CONCLUSION

A high proportion of the bacterial isolates were MDR; had high MDR-I and were positive for ESBL production. The findings provide evidence that the human-dairy interface is one of the important reservoirs of AMR traits. Therefore, the implementation of AMR mitigation strategies is highly needed in the area.

Occurrence of Antibiotic Resistant Bacteria in Flours and Different Plant Powders Used in Cuisine

In recent years, several alimentary diseases have been connected with the consumption or tasting of raw flour and dough. Microbiological quality concern is also raising due to increased consumer demand for plant powders, while some of them can be consumed without prior thermal processing. In this study, we have focused on the occurrence of antibiotic-resistant coliform bacteria and enterococci in flour, plant powder and dough from Slovak retail. Our results indicated the presence of both total and antibiotic-resistant coliform bacteria and enterococci in the flour and powder samples. Lower numbers of the total, as well as resistant bacteria, were detected in flours compared to plant powders. Coliform bacteria isolates were predominantly identified as Klebsiella spp. and Enterobacter spp. Ampicillin resistance appeared in 97% of isolates followed by chloramphenicol resistance (22%) and tetracycline resistance (17%). The presence of the bla_SHV gene was confirmed in 13% of isolates. The tetA and tetE genes were present in 25% of isolates of coliform bacteria. The presence of enterococci was detected only in plant powders. Antibiotic-resistant strains were identified as the following: Enterococcus casseliflavus, E. gallinarium and E. faecium. Despite the isolates showing resistance to vancomycin, the presence of the vanA gene was not detected. The majority of antibiotic-resistant isolates belonged to the group of medium biofilm producers. None of these isolates showed efflux pump overproduction. Antibiotic-resistant coliform bacteria and enterococci were not detected in the processed doughs.