Determining frequency of genes of CTX-M and CTX-M-15 of producing Enterobacteriaceae of isolated extended-spectrum beta-lactamases from clinical samples of patients referred to training hospitals of Medical Sciences University, Khorramabad, Iran

Molecular study on virulence and resistance genes of ST131 clone (uropathogenic/enteropathogenic Escherichia coli) hybrids in children

Aim: To analyze ST131 clones and other characteristics in uropathogenic and atypical enteropathogenic Escherichia coli hybrids. Methods: Samples were collected from children with urinary tract infections and underwent testing for antimicrobial susceptibility, multidrug resistance and extended-spectrum β-lactamases, in vitro biofilm formation and virulence, resistance genes, hybrid pathotypes and ST131 clones. Results: E. coli isolates showed high levels of antibiotic resistance, extended-spectrum β-lactamase production, virulence genes, multidrug resistance and biofilm formation. Four (5.0%) isolates were identified as uropathogenic/atypical enteropathogenic E. coli hybrids, all of which belonged to the high-risk ST131 clone. Conclusion: Our results provide promising insights about hybrid isolates and should be addressed to improve prevention measures for hybrid pathotypes.

Assessing the Load, Virulence and Antibiotic-Resistant Traits of ESBL/Ampc E. coli from Broilers Raised on Conventional, Antibiotic-Free, and Organic Farms

Poultry is the most likely source of livestock-associated Extended Spectrum Beta-Lactamase (ESBL) and plasmid-mediated AmpC (pAmpC)-producing E. coli (EC) for humans. We tested the hypothesis that farming methods have an impact on the load of ESBL/pAmpC-EC in the gut of broilers at slaughter. Isolates (n = 156) of antibiotic-free (AF), organic (O), and conventional (C) animals were characterized for antibiotic susceptibility and antibiotic resistance genes. Thirteen isolates were whole-genome sequenced. The average loads of ESBL/pAmpC-EC in cecal contents were 4.17 Log CFU/g for AF; 2.85 Log CFU/g for O; and 3.88 Log CFU/g for C type (p < 0.001). ESBL/pAmpC-EC isolates showed resistance to antibiotic classes historically used in poultry, including penicillins, tetracyclines, quinolones, and sulfonamides. Isolates from O and AF farms harbored a lower proportion of resistance to antibiotics than isolates from C farms. Among the determinants for ESBL/pAmpC, CTX-M-1 prevailed (42.7%), followed by TEM-type (29%) and SHV (19.8%). Avian pathogenic E. coli (APEC), belonging to ST117 and ST349, were identified in the collection. These data confirm the possible role of a broiler as an ESBL/AmpC EC and APEC reservoir for humans. Overall, our study suggests that antibiotic-free and organic production may contribute to a reduced exposure to ESBL/AmpC EC for the consumer.

Natural epiestriol-16 act as potential lead molecule against prospective molecular targets of multidrug resistant Acinetobacter baumannii-Insight from in silico modelling and in vitro investigations

The current study aimed to identify putative drug targets of multidrug resistant Acinetobacter baumannii (MDRAb) and study the therapeutic potential of natural epiestriol-16 by computer aided virtual screening and in vitro studies. The clinical isolates (n = 5) showed extreme dug resistance to carbapenems and colistins (p ≤ .05). Computational screening suggested that out of 236 natural molecules selected, 06 leads were qualified for drug likeliness, pharmacokinetic features and one potential molecule namely natural epiestriol-16 (16b-Hydroxy-17a-estradiol) exhibited significant binding potential towards four prioritised drug targets in comparison with the binding of faropenem to their usual target. Natural epiestriol demonstrated profound binding to the outer membrane protein (Omp38), protein RecA (RecA), orotate phosphoribosyltransferase (PyrE) and orotidine 5'-phosphate decarboxylase (PyrF) with binding energy of -6.0, -7.3, -7.3 and -8.0 kcal/mol respectively. MD simulations suggested that 16-epiestriol-receptor complexes demonstrated stability throughout the simulation. The growth curve and time kill assays revealed that MDRAb showed resistance to faropenem and polymyxin-B and the pure epiestriol-16 showed significant inhibitory properties at a concentration of 200 μg/mL (p ≤ .5). Thus, natural epiestriol-16 can be used as potential inhibitor against the prioritised targets of MDRAb and this study provide insight for drug development against carbapenem and colistin resistant A. baumannii.

Antibiotic-resistant commensal Escherichia coli are less frequently isolated from poultry raised using non-conventional management systems than from conventional broiler

Poultry production is the fastest growing meat sector worldwide. In the last five years, growing concerns have been expressed by international health agencies and consumers about the transmission of antibiotic-resistant bacteria from poultry meat to human. Consequently, poultry producers have adopted alternative production systems based on reduced antibiotic usage, including organic and antibiotic-free (AF) production. However, the effect of these production systems on the antibiotic resistance of the gut flora in slaughtered poultry has been poorly investigated. We hypothesized that organic and AF production systems reduce the risk of antibiotic resistance in the commensal Escherichia coli of broilers at slaughter compared with conventional production. Cecal content from broilers raised in conventional (292), AF (291), or organic (272) flocks (855 broilers in total) belonging to the same company was sampled. E. coli loads [colony-forming units (CFU/g)] and numbers of E. coli resistant to nalidixic acid (E. coli^nal) were determined for each sample. Antibiotic susceptibility of one isolate per sample was evaluated using the disc diffusion method; colistin resistance was determined by using the broth microdilution method. The differences in bacterial loads from the three production types were evaluated using one-way ANOVA. Differences in the proportion of resistant isolates in the three production lines were evaluated using Pearson's χ² or Fisher's test. The strength of the association was evaluated by using odds ratio (OR), with the conventional production type as a reference (OR = 1). Overall, the analysis revealed a high level of resistance (50% or higher) to ampicillin, cefazolin, sulfonamides, nalidixic acid, and tetracycline, independently of the production type. High proportion of ciprofloxacin resistance (52%) was observed, with 4.5% isolates resistant to cefotaxime and 1.8% resistant to colistin. The average loads (log CFU/g cecal content) of E. coli^nal were determined as 6.84 for AF, 6.38 for organic type, and 7.27 for conventional type. The difference was significant (p < 0.00001). Interestingly, broilers from AF flocks had higher E. coli^nal loads than broilers from organic flocks. This trend (conventional > AF > organic) was confirmed by qualitative data. However, the magnitude of the effect, measured as a reduced risk of resistance, varied broadly for the antibiotics tested. These findings suggest that poultry production systems alternative to the conventional broiler production are associated with reduced frequency of antibiotic-resistant E. coli among the commensal gut flora, posing a lower risk to the environment and the consumer.