High-risk clonal lineages among extended-spectrum ß-lactamase producing Escherichia coli and Klebsiella pneumoniae from urban and rural stagnant water samples in Tunisia.

This study sought to investigate the occurrence and subsequently to characterize extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae from urban and rural stagnant water samples during the wet season (December to February) in several regions of northern Tunisia. From 56 stagnant water samples, 14 ESBL-producing Enterobacteriaceae were recovered, including 9 Escherichia coli, 3 Klebsiella pneumoniae, and 2 K. oxytoca. Most isolates were multidrug-resistant, with ESBL production primarily encoded by blaCTX-M-15 (n = 8) and blaCTX-M-1 (n = 4) followed by blaCTX-M-55 (n = 1) and blaTEM-26 (n = 1). One K. pneumoniae isolate co-harbored blaKPC and blaCTX-M-15 genes. Class 1 integrons were detected in 4 isolates, however, sul1, sul2, and aac(6')-Ib-cr genes were detected in eleven, two, and four isolates, respectively. The nine E. coli isolates belonged to seven sequence types namely, B2/ST131 (3 isolates), A/ST164, A/ST10, A/ST224, A/ST38, A/ST155, and A/ST69 (each of them one isolate). The three K. pneumoniae isolates were assigned to three sequence types: ST101, ST405 (harboring CTX-M-15 and KPC), and ST1564. Overall, the phenotypic and genotypic traits of collected isolates mirror the molecular epidemiology of ESBL-producing enterobacteria in Tunisia and highlight the potential role of stagnant water in both urban and rural areas as a reservoir of ESBL-producing Enterobacteriaceae.

Selection and Characterization of Bacteriocinogenic Lactic Acid Bacteria from the Intestine of Gilthead Seabream (Sparus aurata) and Whiting Fish (Merlangius merlangus): Promising Strains for Aquaculture Probiotic and Food Bio-Preservation.

This study sought to evaluate the probiotic properties and the food preservation ability of lactic acid bacteria isolates collected from the intestines of wild marine fishes (gilthead seabream (Sparus aurata) (n = 60) and whiting fish (Merlangius merlangus) (n = 40)) from the Mediterranean sea in the area of Mostaganem city, Algeria. Forty-two isolates were identified as: Enterococcus durans (n = 19), Enterococcus faecium (n = 15), Enterococcus faecalis (n = 4), Lactococcus lactis subp. lactis (n = 3), and Lactobacillus plantarum (n = 1). All isolates showed inhibition to at least one indicator strain, especially against Listeria monocytogenes, Staphylococcus aureus, Paenibacillus larvae, Vibrio alginolyticus, Enterococcus faecalis, Bacillus cereus, and Bacillus subtilis. In all collected isolates, PCR analysis of enterocin-encoding genes showed the following genes: entP (n = 21), ent1071A/B (n = 11), entB (n = 8), entL50A/B (n = 7), entAS48 (n = 5), and entX (n = 1). Interestingly, 15 isolates harbored more than one ent gene. Antimicrobial susceptibility, phenotypic virulence, and genes encoding virulence factors were investigated by PCR. Resistance to tetracycline (n = 8: tetL + tetK), erythromycin (n = 7: 5 ermA, 2 msrA, and 1 mef(A/E)), ciprofloxacin (n = 1), gentamicin (n = 1: aac(6')-aph(2″)), and linezolid (n = 1) were observed. Three isolates were gelatinase producers and eight were α-hemolytic. Three E. durans and one E. faecium harbored the hyl gene. Eight isolates showing safety properties (susceptible to clinically relevant antibiotics, free of genes encoding virulence factors) were tested to select probiotic candidates. They showed high tolerance to low pH and bile salt, hydrophobicity power, and co-culture ability. The eight isolates showed important phenotypic and genotypic traits enabling them to be promising probiotic candidates or food bio-conservers and starter cultures.

Occurrence of High-Risk Clonal Lineages ST58, ST69, ST224, and ST410 among Extended-Spectrum ß-Lactamase-Producing Escherichia coli Isolated from Healthy Free-Range Chickens (Gallus gallus domesticus) in a Rural Region in Tunisia.

Antimicrobial-resistant Escherichia coli isolates have emerged in various ecologic compartments and evolved to spread globally. We sought to (1.) investigate the occurrence of ESBL-producing E. coli (ESBL-Ec) in feces from free-range chickens in a rural region and (2.) characterize the genetic background of antimicrobial resistance and the genetic relatedness of collected isolates. Ninety-five feces swabs from free-range chickens associated with two households (House 1/House 2) in a rural region in northern Tunisia were collected. Samples were screened to recover ESBL-Ec, and collected isolates were characterized for phenotype/genotype of antimicrobial resistance, integrons, and molecular typing (pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST)). Overall, 47 ESBL-Ec were identified, with the following genes detected: 35 blaCTX-M-1, 5 blaCTX-M-55, 5 blaCTX-M-15, 1 blaSHV-2, and 1 blaSHV-12. Resistance to fluoroquinolones, tetracycline, sulfonamides, and colistin was encoded by aac(6')-Ib-cr (n = 21), qnrB (n = 1), and qnrS (n = 2); tetA (n = 17)/tetB (n = 26); sul1 (n = 29)/sul2 (n = 18); and mcr-2 (n = 2) genes, respectively. PFGE and MLST identified genetic homogeneity of isolates in House 1; however, isolates from House 2 were heterogeneous. Notably, among nine identified sequence types, ST58, ST69, ST224, and ST410 belong to pandemic high-risk clonal lineages associated with extrapathogenic E. coli. Minor clones belonging to ST410 and ST471 were shared by chickens from both households. The virulence genes fyuA, fimH, papGIII, and iutA were detected in 35, 47, 17, and 23 isolates, respectively. Findings indicate a high occurrence of ESBL-Ec in free-range chickens and highlight the occurrence of pandemic zoonotic clones.

Hiding in plain sight-wildlife as a neglected reservoir and pathway for the spread of antimicrobial resistance: a narrative review.

Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant 'hotspots' of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant bacteria and genes as they originate and emanate from livestock and human hosts have been extensively studied over the past 30 years, numerous ecological niches have received considerably less attention. In the current descriptive review, the authors have sought to highlight the importance of wildlife as sources/reservoirs, pathways and receptors of ARB/ARGs in the environment, thus paving the way for future primary research in these areas.

Species distribution and genes encoding antimicrobial resistance in enterococcus spp. isolates from rabbits residing in diverse ecosystems: A new reservoir of linezolid and vancomycin resistance.

AIMS: Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it seems that rearing conditions have important impact on emergence and spread of antimicrobial-resistant bacteria. Thus, the authors sought to (1) assess the role of rabbits residing across diverse ecosystems as potential reservoirs of antimicrobial-resistant enterococci and (2) investigate the genetic background of detected resistances. METHODS AND RESULTS: Faecal samples from 60 healthy farmed rabbits (one farm), 35 laboratory rabbits and 31 wild rabbits were analysed. Overall, 97 enterococci isolates were accumulated, as follows: 44 E. faecium, 37 E. faecalis, 7 E. gallinarum, 5 E. durans and 4 E. avium. E. faecalis isolates were statistically associated with farm rabbits and wild rabbits (p < 0.05). High rates of resistance were observed for tetracycline (60.8%; tetM [n = 48; 81.3%], tetO [n = 7; 11.8%] and tetL [n = 1; 1.7%]), erythromycin (43.3%; msr(A) [n = 14; 33.3%] and ermB [n = 13; 31%]), ampicillin (29.9%), streptomycin (26.8%; ant(6)-Ia [n = 3, 11.5%]) and vancomycin (21.6%; vanA [one E. faecium + one E. faecalis; 9.5%]). Low frequencies of resistance were observed for teicoplanin (9.2%), linezolid (8.2%), ciprofloxacin (7.2%) and gentamicin (1%; aac(6')-Ie-aph(2″)-Ia). Resistance to ampicillin and vancomycin was associated with laboratory rabbits (p < 0.05). Int-Tn (Tn916/1545) was detected in 27 (27.8%) isolates, of which 10 isolates co-harboured tetM and ermB genes, while 16 comprised tetM. CONCLUSION: Findings indicate that clinically relevant enterococci species isolated from rabbits are frequently resistant to antimicrobials and harbour a range of genes associated with the Tn916/1545 family. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the high rates of antimicrobial-resistant enterococci from rabbits and the occurrence of both vancomycin- and linezolid-resistant isolates, potentially representing a very serious threat to human and animal health.

Genetic Background of Antimicrobial Resistance in Multiantimicrobial-Resistant Escherichia coli Isolates from Feces of Healthy Broiler Chickens in Tunisia.

Multiantimicrobial-resistant Escherichia coli isolates are a global human health problem causing increasing morbidity and mortality. Genes encoding antimicrobial resistance are mainly harbored on mobile genetic elements (MGEs) such as transposons and plasmids as well as integrons, which enhance their rapid spread. The aim of this study was to characterize 83 multiantimicrobial-resistant E. coli isolates recovered from healthy broiler chickens. Among 78 tetracycline-resistant isolates, the tetA, tetB, and tetC genes were detected in 59 (75.6%), 14 (17.9%), and one (1.2%) isolates, respectively. The sul1, sul2, and sul3 genes were detected 31 (46.2%), 16 (23.8%), and 6 (8.9%) isolates, respectively, among 67 sulfonamide-resistant isolates. The PCR-based replicon typing method showed plasmids in 29 isolates, IncFIB (19), IncI1-Iγ (17), IncF (14), IncK (14), IncFIC (10), IncP (8), IncY (3), IncHI2 (1), and IncX (1). The class 1 and 2 integrons were detected in 57 and 2 isolates, respectively; one isolate harbored both integrons. Seven and one gene cassette arrays were identified in class 1 and class 2 integrons, respectively. Our findings show that multiantimicrobial-resistant E. coli isolates from chickens serve as reservoirs of highly diverse and abundant tet and sul genes and plasmid replicons. Such isolates and MGEs pose a potential health threat to the public and animal farming.