Lactic acid bacteria from kefir grains: Potential probiotics with antagonistic activity against multidrug resistant Gram-negative bacteria

Aims@#This study aimed to isolate and identify lactobacilli strains that have antagonistic activity against multidrug resistant (MDR) isolates of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and evaluate their probiotic properties.@*Methodology and results@#Twenty-one Lactobacillus isolates were collected, and their antimicrobial activity was assessed by agar well diffusion, broth microdilution and time-kill test. The probiotic potential of the isolates was evaluated as well. The bacterial culture and cell free supernatant (CFS) of all isolates exhibited antibacterial activity against all MDR isolates. Out of 21 isolates, 4 isolates (A31, B35, S20 and S25) displayed the highest antimicrobial activity and further evaluated. The minimum inhibitory percentages of CFS from selected isolates against pathogens ranged from 10 to 30% and the bactericidal percentages ranged from 20 to 50%. The inhibitory activity of CFS was not changed after heating but abrogated as the pH neutralized. The growth kinetic of the MDR pathogens was significantly reduced in the presence of the CFS of all isolates. The isolates had a less than 1-log reduction in their viability in acid tolerance test and could grow in the presence of 0.3% bile salts. Strains S20, S25 and B35 exhibited high coaggregation with E. coli (51.7-73.3%), P. aeruginosa (53.7-69.3%) and K. pneumoniae (49.7-65.3%). Molecular identification revealed that the isolates were Lactobacillus rhamnosus (B35) and Lactobacillus paracasei (S20, S25, A31). @*Conclusion, significance and impact of study@#The results suggest that these lactobacilli isolates may have potential applications for controlling and preventing colonization of infections caused by MDR pathogens.

[ survey of extended spectrum beta lactamase producing Enterobacteriaceae in hospital effluents]

Background: Beta-lactams are the largest group of antibiotics used by hospitals to treat infections caused by Gram-negative bacteria. Enterobacteriaceae, natural microbiota of the human gastrointestinal tract, represent a large part of bacterial communities colonizing hospital effluents, and they could be a source of genes encoding extended-spectrum-beta-lactamases [ESBLs]. Those genes may be transmitted to other bacteria present in sewage and the environment

Materials and methods: In this descriptive study, the isolated strains were identified by biochemical methods in accordance with Bergey's manual of systematic bacteriology. Screening and phenotypic confirmatory test for ESBL production were performed using standard double disc diffusion methods. Each initial ESBL screening test isolate was investigated for the presence of bla CTX-M genes via polymerase chain reaction [PCR] using gene-specific primers

Results: Of 108 bacterial isolates, 52 [48%] were phenotypically ESBL-positive, but only 32 [29.63%] isolates harbored bla CTX-M gene. Escherichia coli and Citrobacter spp. were the most frequently identified ESBL-positive strains

Conclusion: The results showed that ESBL-genes were presented in the hospital wastewater and could be threat for public health

[Detection of antibiotic resistant Gram negative bacteria and plasmid profiling of multi-drug resistant isolates in hospital effluents]

Waste effluents from hospitals contain high numbers of resistant bacteria. Among resistant strains' Gram negative bacilli are able to survive for a long time in the environment and act as natural reservoirs of resistant genes. The aim of this study was to determine the prevalence of antibiotic resistant Gram negative bacilli and the plasmid profile of multi resistant bacteria in hospital effluents. In this experimental study, the antibiotic resistance patterns of the isolated strains were assayed by disc diffusion method. The isolates were identified by biochemical methods in accordance with Bergey's Manual of Systematic Bacteriology. Plasmid extraction was carried out by alkaline lysis technique. A total of 320 bacterial isolates were picked from the sewage samples. Gram-negative rods represented the main bulk [62.5%], followed by Gram-positive rods [34.4%] and Gram positive cocci [3.1%]. The most common isolates were Escherichia coli [33%] followed by Psudomonas aeruginosa [17 %]. The gram-negative rods were tested for their susceptibility for eight antibiotics. The results showed that gentamicin and cefttriaxone were the most effective antibiotics and ampicillin had the least efficacy. The results also showed that all of the isolates were multi-drug resistant and 6% of them were resistant to all of the tested antibiotics. Isolates with high multi-drug resistance profiles were found to possess multiple plasmids with sizes in the range of 1.5 to 24.5 KB. The results show that the multi-drug resistant bacteria are present in the hospital waste and could be threat for public health

[Isolation and molecular identification of an antibiotic resistant acinetobacter sp. from hospital sewage and its plasmid profile]

The emergence of antimicrobial-resistant genes and the indiscriminate use of antibiotics contribute to the dissemination of resistant pathogens in the environment. The objective of the present study was isolation and molecular identification of antibiotic resistant bacteria from the hospital sewage and investigation of the role of plasmid in resistance mechanism. In this experimental study, the antibiotic resistance patterns of the isolated strains from hospital effluent samples were assayed by disc diffusion method. The selected isolate was identified by morphological and biochemical methods in accordance with Bergey's Manual of Systematic Bacteriology. Phylogenetic analysis was performed based on 16S rRNA gene sequences. Plasmid extraction was carried out by alkaline lysis technique and curing of plasmids performed by Ethidium bromide. Ten bacterial strains were isolated from hospital sewage. Results of antibiotic susceptibility test showed that all of the isolates were multi-drug resistant. One of the isolates [ST1] was resistant to all of the tested antibiotics. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Acinetobacter then designated as Acinetobacter sp. HM_C. Phylogenetically the closest relative of strain was Acinetobacter baumanni IARI-V-4. Curing experiments by Ethidium bromide caused the elimination of all plasmids. The sensitivity of the plasmid cured ST1 to gentamycin, and amikacin indicated that the genes encoding resistance to gentamycin, and amikacin were located on plasmid. Hospital effluents are important materials in dissemination of multidrug resistant bacteria and their resistant genes into the environment