Occurrence of antimicrobial resistance and virulence genes, and distribution of enterococcal clonal complex 17 from animals and human beings in Korea

Integrating loop-mediated isothermal amplification with lateral flow assay to achieve a highly sensitive method for detecting Streptococcus suis Genome in raw pork

Streptococcus suis (S.suis), a zoonotic foodborne pathogen prevalent in Southeast Asia, poses a substantial threat to human and animal health because of its ability to cause severe and life-threatening illnesses. To address this challenge, a rapid and highly sensitive detection platform for S. suis in raw pork was developed by integrating loop-mediated isothermal amplification (LAMP) and a lateral flow assay (LFA), S. suis LAMP-LFA. LAMP reactions targeting the S. suis glutamate dehydrogenase (gdh) gene were optimized for specific detection of S. suis within 45 min at an isothermal temperature of 65 °C. The assay exhibited marked sensitivity, with a detection limit of 100 fg for genomic DNA extracted from S. suis cultures. Notably, this method showed no cross-reactivity with other bacterial contaminants commonly found in raw pork. The resulting LAMP amplicons were effectively detected using LFA, with a test limit of 101 CFU per 25 g of raw pork. S. suis LAMP-LFA proved to be highly specific and reliable, with no false-positives detected in spiked pork samples or pork samples containing other bacterial contaminants. Due to its high sensitivity, specificity, and rapid turnaround time, the proposed technique has immense potential as a field-deployable screening test for S. suis detection in raw pork, contributing to enhanced food safety and public health protection.

Antimicrobial Resistance Profiles of Enterococcus faecium and Enterococcus faecalis Isolated from Healthy Dogs and Cats in South Korea

Enterococcus spp. are typically found in the gastrointestinal tracts of humans and animals. However, they have the potential to produce opportunistic infections that can be transmitted to humans or other animals, along with acquired antibiotic resistance. In this study, we aimed to investigate the antimicrobial resistance profiles of Enterococcus faecium and Enterococcus faecalis isolates obtained from companion animal dogs and cats in Korea during 2020-2022. The resistance rates in E. faecalis towards most of the tested antimicrobials were relatively higher than those in E. faecium isolated from dogs and cats. We found relatively higher resistance rates to tetracycline (65.2% vs. 75.2%) and erythromycin (39.5% vs. 49.6%) in E. faecalis isolated from cats compared to those from dogs. However, in E. faecium, the resistance rates towards tetracycline (35.6% vs. 31.5%) and erythromycin (40.3% vs. 35.2%) were comparatively higher for dog isolates than cats. No or very few E. faecium and E. faecalis isolates were found to be resistant to daptomycin, florfenicol, tigecycline, and quinupristin/dalfopristin. Multidrug resistance (MDR) was higher in E. faecalis recovered from cats (44%) and dogs (33.9%) than in E. faecium isolated from cats (24.1%) and dogs (20.5%). Moreover, MDR patterns in E. faecalis isolates from dogs (27.2%) and cats (35.2%) were shown to encompass five or more antimicrobials. However, E. faecium isolates from dogs (at 13.4%) and cats (at 14.8%) were resistant to five or more antimicrobials. Taken together, the prevalence of antimicrobial-resistant enterococci in companion animals presents a potential public health concern.

Prevalence, antimicrobial resistance pattern, and associated factors of Salmonella and Shigella among under five diarrheic children attending public health facilities in Debre Markos town, Northwest Ethiopia

Background

Under five children are at risk of diarrhea-associated morbidity and mortality. Salmonella and Shigella are major causes of diarrhea in under-five children, especially in developing countries. This study aimed to assess the prevalence, antimicrobial resistance pattern, and associated factors of Salmonella and Shigella among under-five diarrheic children in Debre Markos town public health facilities.

Methods

A cross-sectional study was conducted at public health facilities in Debre Markos town using a consecutive convenient sampling technique. Data on socio-demographic and associated factors were collected using a structured questionnaire. Salmonella serovars and Shigella species were identified using MacConkey, Xylose Lysine Deoxycholate, Salmonella Shigella agar, and biochemical tests. The antimicrobial resistance pattern was determined by using the modified Kirby-Bauer disk diffusion technique.

Results

The overall prevalence of Salmonella and Shigella was 11.7% (26/222; 95% CI = 7.2-17.5%). Isolated Salmonella serovars showed a higher rate of resistance (85.7%, 6/7) for both Ampicillin and Amoxicillin/Clavulanic acid while Shigella isolates showed a higher resistance rate to Amoxicillin/Clavulanic acid (78.9%, 15/19) and Ampicillin (73.7%, 14/19). The overall multidrug resistance (MDR) rate of Salmonella and Shigella isolates was 88.5% (23/26). Parent/guardian educational status ≤ elementary school (AOR = 3.783; 95% CI = 1.28-11.19; P = 0.016), presence of two or more under-five children in the family (AOR = 8.999; 95% CI = 2.93-27.69; P < 0.001), unimproved source of drinking water (AOR = 5.010; 95% CI = 1.56-16.10; P = 0.007), the habit of storing cooked foods for later use (AOR = 3.199; 95% CI = 1.07-9.54; P = 0.037), attendance of the child at social gatherings (AOR = 5.387; 95% CI = 1.78-16.35; P = 0.003), and infrequent child fingernail trimming (every ≥ 2 weeks; AOR = 4.693; 95% CI = 1.47-14.94; P = 0.009) showed statistically significant association with the prevalence of culture-confirmed Salmonella and Shigella isolates.

Conclusion

The prevalence of culture-confirmed Salmonella and Shigella isolates was significantly high in the study area. Salmonella and Shigella isolates exhibited a high rate of MDR pattern. Parent/guardian education level below the elementary school, the presence of two or more under-five children in the family, using unimproved water source, a habit of storing cooked food, and infrequent fingernail trimming were independent predictors of culture-confirmed Salmonella and Shigella. Therefore, besides public health measures, regular surveillance of the prevalence and antimicrobial resistance pattern of Salmonella and Shigella should be routinely practiced in the study setting.

Prevalence and antimicrobial resistance patterns of Enterococcus species isolated from laying hens in Lusaka and Copperbelt provinces of Zambia: a call for AMR surveillance in the poultry sector

Background

The use of antimicrobials in layer poultry production for improved production, growth promotion, prophylaxis and treatment purposes has contributed to the development of antimicrobial resistance (AMR) in poultry. In Zambia, there is a paucity of information on the prevalence and AMR patterns of Enterococcus species isolated from laying hens.

Objectives

This study investigated the prevalence and AMR patterns of enterococci isolated in layer hens in Lusaka and Copperbelt provinces of Zambia.

Methods

A cross-sectional study was conducted from September 2020 to April 2021. Three hundred and sixty-five pooled cloacal swab samples were collected from 77 layer poultry farms. Enterococci identification and confirmation were performed using Analytical Profile Index (API 20 STREP) and 16S rRNA sequencing, respectively. A panel of nine antibiotics was used for antibiotic susceptibility testing and interpreted according to the CLSI 2020 guidelines. Data were analysed using SPSS version 23 and WHONET 2020.

Results

A total of 308 (83%) single Enterococcus species isolates were obtained and showed resistance to tetracycline (80.5%), erythromycin (53.6%), quinupristin/dalfopristin (53.2%), ampicillin (36.72%), vancomycin (32.8%), linezolid (30.2%), ciprofloxacin (11.0%), nitrofurantoin (6.5%) and chloramphenicol (3.9%). The prevalence of enterococci resistant to at least one antibiotic was 99.4% (n = 306), of which 86% (n = 265) were MDR.

Conclusions

This study found a high prevalence of antimicrobial-resistant enterococci. The presence of MDR requires urgent intervention and implementation of AMR surveillance strategies and antimicrobial stewardship programmes in layer poultry production in Zambia.

Longitudinal Analysis of Antimicrobial Resistance among Enterococcus Species Isolated from Australian Beef Cattle Faeces at Feedlot Entry and Exit

Enterococcus faecium are commensal bacteria inhabiting the gastrointestinal tract of animals and humans and an important cause of drug-resistant nosocomial infections. This longitudinal study aimed to determine whether changes in the antimicrobial resistance (AMR) phenotype and genotype occurred among Enterococcus spp. isolated from cattle rectal samples obtained at the entry to and exit from an Australian feedlot. The samples obtained at the feedlot induction yielded enterococci (104/150; 69.3%), speciated as E. hirae (90/104; 86.5%), E. faecium (9/104; 8.7%), E. mundtii (3/104; 2.9%), E. durans, and E. casseliflavus (1/104; 1.0% each). AMR was observed to lincomycin (63/104; 60.6%), daptomycin (26/104; 25.0%), nitrofurantoin (9/104; 8.7%), ciprofloxacin (7/104; 6.7%), tetracycline (5/104; 4.8%), tigecycline (4/104; 3.9%), and quinupristin/dalfopristin (3/104; 2.9%). From the rectal swab samples collected at the abattoir from the same animals (i.e., the feedlot exit), the enterococci recovery was significantly higher (144/150; 96.0%), with a marked shift in species distribution dominated by E. faecium (117/144; 81.3%). However, the prevalence of AMR to individual antimicrobials remained largely static between the entry and exit except for the increased resistance to nitrofurantoin (77/144; 53.5%) and quinupristin/dalfopristin (26/144; 18.1%). Overall, 13 AMR genes were observed among the 62 E. faecium isolates. These included aac(6')Ii, aac(6')-Iid, and ant(6)-Ia (aminoglycosides); eatAv, lnu(G), vat(E), msr(C), and erm(B) (macrolides, lincosamides, and streptogramins); efmA (fluoroquinolones); and tet(45), tet(L), tet(M), and tet(S) (tetracyclines). The results confirm the presence of fluoroquinolone- and streptogramin-resistant enterococci in cattle faeces at the feedlot entry in the absence of antimicrobial selection pressure. E. faecium, exhibiting increased nitrofurantoin resistance, became the dominant Enterococcus spp. during the feeding period.

Antimicrobial Resistance, Biofilm Formation, and Virulence Genes in Enterococcus Species from Small Backyard Chicken Flocks

Backyard birds are small flocks that are more common in developing countries. They are used for poultry meat and egg production. However, they are also implicated in the maintenance and transmission of several zoonotic diseases, including multidrug-resistant bacteria. Enterococci are one of the most common zoonotic bacteria. They colonize numerous body sites and cause a wide range of serious nosocomial infections in humans. Therefore, the objective of the present study was to investigate the diversity in Enterococcus spp. in healthy birds and to determine the occurrence of multidrug resistance (MDR), multi-locus sequence types, and virulence genes and biofilm formation. From March 2019 to December 2020, cloacal swabs were collected from 15 healthy backyard broiler flocks. A total of 90 enterococci strains were recovered and classified according to the 16S rRNA sequence into Enterococcus faecalis (50%); Enterococcus faecium (33.33%), Enterococcus hirae (13.33%), and Enterococcus avium (3.33%). The isolates exhibited high resistance to tetracycline (55.6%), erythromycin (31.1%), and ampicillin (30%). However, all of the isolates were susceptible to linezolid. Multidrug resistance (MDR) was identified in 30 (33.3%) isolates. The enterococci AMR-associated genes ermB, ermA, tetM, tetL, vanA, cat, and pbp5 were identified in 24 (26.6%), 11 (12.2%), 39 (43.3%), 34 (37.7%), 1 (1.1%), 4 (4.4%), and 23 (25.5%) isolates, respectively. Of the 90 enterococci, 21 (23.3%), 27 (30%), and 36 (40%) isolates showed the presence of cylA, gelE, and agg virulence-associated genes, respectively. Seventy-three (81.1%) isolates exhibited biofilm formation. A statistically significant correlation was obtained for biofilm formation versus the MAR index and MDR. Multi-locus sequence typing (MLST) identified eleven and eight different STs for E. faecalis and E. faecium, respectively. Seven different rep-family plasmid genes (rep1–2, rep3, rep5–6, rep9, and rep11) were detected in the MDR enterococci. Two-thirds (20/30; 66.6%) of the enterococci were positive for one or two rep-families. In conclusion, the results show that healthy backyard chickens could act as a reservoir for MDR and virulent Enterococcus spp. Thus, an effective antimicrobial stewardship program and further studies using a One Health approach are required to investigate the role of backyard chickens as vectors for AMR transmission to humans.

Pet husbandry as a risk factor for colonization or infection with MDR organisms: a systematic meta-analysis

BACKGROUND

MDR organisms (MDROs) pose a relevant risk for patients in modern healthcare. Although ownership of pet animals is common and owners and pets commonly live in close contact, it is still unclear whether pet ownership may be considered as a risk factor for MDRO acquisition prior to hospitalization.

METHODS

We performed three separate meta-analyses in accordance with the PRISMA guidelines, assessing contact to pets as a risk factor for acquisition of MRSA, VRE and MDR Gram-negatives [namely third-generation cephalosporin-resistant Enterobacterales (3GCRE) and carbapenem-resistant Enterobacterales (CRE)].

RESULTS

We calculated an increased risk of MRSA carriage for dog owners [risk ratio (RR) 2.28, 95% CI 1.47-3.56]. Meta-analysis did not show a significantly higher risk for 3GCRE colonization among owners of different pet species compared with non-pet owners (RR 1.18, 95% CI 0.83-1.68 for pet owners in general, RR 0.88, 95% CI 0.56-1.40 for dog owners, RR 1.16, 95% CI 0.58-2.34 for cat owners, RR 1.34, 95% CI 0.43-4.18 for rodent owners, RR 0.91, 95% CI 0.38-2.18 for bird owners, and RR 2.34, 95% CI 0.33-16.63 for lizard/frog owners). For VRE, there were insufficient data to perform a meta-analysis.

CONCLUSIONS

Our analyses suggest contact to pet animals is a risk factor for MRSA, but not for 3GCRE/CRE acquisition. Evaluation of the underlying literature suggested a possible role of pet animals as: (i) vectors for the transmission of MDROs between livestock and humans; as well as (ii) a reservoir for MDROs. Pets, therefore, may promote transmission and reinfection of humans.

Nationwide Surveillance on Antimicrobial Resistance Profiles of Enterococcus faecium and Enterococcus faecalis Isolated from Healthy Food Animals in South Korea, 2010 to 2019

Intestinal commensal bacteria are considered good indicators for monitoring antimicrobial resistance. We investigated the antimicrobial resistance profiles and resistance trends of Enterococcus faecium and Enterococcus faecalis isolated from food animals in Korea between 2010 and 2019. E. faecium and E. faecalis, isolated from chickens and pigs, respectively, presented a relatively high resistance rate to most of the tested antimicrobials. We observed high ciprofloxacin (67.9%), tetracycline (61.7%), erythromycin (59.5%), and tylosin (53.0%) resistance in E. faecium isolated from chickens. Similarly, more than half of the E. faecalis isolates from pigs and chickens were resistant to erythromycin, tetracycline and tylosin. Notably, we observed ampicillin, daptomycin, tigecycline and linezolid resistance in a relatively small proportion of enterococcal isolates. Additionally, the enterococcal strains exhibited an increasing but fluctuating resistance trend (p < 0.05) to some of the tested antimicrobials including daptomycin and/or linezolid. E. faecalis showed higher Multidrug resistance (MDR) rates than E. faecium in cattle (19.7% vs. 8.6%, respectively) and pigs (63.6% vs. 15.6%, respectively), whereas a comparable MDR rate (≈60.0%) was noted in E. faecium and E. faecalis isolated from chickens. Collectively, the presence of antimicrobial-resistant Enterococcus in food animals poses a potential risk to public health.

Multidrug Resistance in Pasteurellaceae Associated With Bovine Respiratory Disease Mortalities in North America From 2011 to 2016

Multidrug-resistant (MDR; resistance to ≥3 antimicrobial classes) members of the Pasteurellaceae family may compromise the efficacy of therapies used to prevent and treat bovine respiratory disease (BRD) in feedlot cattle. This study examined the prevalence of multidrug resistance in strains of Mannheimia haemolytica and Pasteurella multocida collected from BRD cattle mortalities in North America. Isolates of M. haemolytica (n = 147) and P. multocida (n = 70) spanning 69 Alberta feedlots from 2011 to 2016 and two United States feedlots from 2011 to 2012 were examined for antimicrobial resistance (AMR) in association with integrative and conjugative elements (ICEs). Overall, resistance was high in both bacterial species with an increase in the prevalence of MDR isolates between 2011 and 2016. Resistance to >7 antimicrobial drugs occurred in 31% of M. haemolytica and 83% of P. multocida isolates. Resistance to sulfadimethoxine, trimethoprim/sulfamethoxazole, neomycin, clindamycin oxytetracycline, spectinomycin, tylosin, tilmicosin, and tulathromycin was most common. Although >80% of strains harbored three or more ICE-associated genes, only 12% of M. haemolytica and 77% of P. multocida contained all six, reflecting the diversity of ICEs. There was evidence of clonal spread as P. multocida and M. haemolytica isolates with the same pulsed-field gel electrophoresis profile from the United States in 2011 were isolated in Alberta in 2015–2016. This work highlights that MDR strains of Pasteurellaceae containing ICEs are widespread and may be contributing to BRD therapy failure in feedlot cattle. Given the antimicrobial resistance gene profiles identified, these MDR isolates may be selected for by the use of macrolides, tetracyclines, and/or in-feed supplements containing heavy metals.

Distribution and antimicrobial resistance profiles of bacterial species in stray dogs, hospital-admitted dogs, and veterinary staff in South Korea

Transferring antimicrobial-resistant bacteria from companion animals to human hosts has become increasingly common. Data regarding antimicrobial susceptibility could help veterinarians to select the most appropriate antibiotic treatment. However, standardized and ongoing surveys regarding antimicrobial resistance remain limited. In this study, we investigated the antimicrobial-susceptibility patterns and trends of bacteria isolated from stray dogs, hospital-admitted dogs, and veterinary staff in South Korea from 2018 to 2019. The minimum inhibitory concentrations of different antimicrobials for Staphylococcus spp., Enterobacterales, and Enterococcus spp. were determined to establish representatives of different antibiotic classes relevant for treatment or surveillance. For coagulase-positive and -negative Staphylococci, resistance to gentamicin was <27 %, while that to ampicillin and penicillin was high (33-80 %). The mecA-detection rates among staphylococcal isolates were 28.5 %, 42.6 %, and 32 % from stray dogs, hospital-admitted dogs, and veterinary staffs, respectively. For Enterobacterales, resistance to carbapenems was low (0-6%). A total of 31.2 % and 18.9 % of Enterobacterales isolates from stray dogs and hospital-admitted dogs were confirmed to possess at least one of bla_CTX-M, bla_SHV, or bla_TEM. Additionally, Enterococcus spp. isolates showed no resistance to vancomycin. These results demonstrate that dogs are commonly colonized with antimicrobial-resistant bacteria and highlight the need for further investigation.

Occurrence, Antimicrobial Resistance and Molecular Diversity of Enterococcus faecium in Processed Pork Meat Products in Korea

Because Enterococcus faecium is an important nosocomial pathogen and sentinel organism for tracking antimicrobial resistance, information on the contamination and antimicrobial resistance patterns of E. faecium in food are essential to public health and food safety. We analyzed the occurrence of E. faecium in retail pork meat products (n = 124), and antimicrobial resistance of 30 E. faecium isolates were examined against 14 antimicrobials using the broth dilution test and disc diffusion test. Rep-PCR-based molecular diversity was also analyzed using Deviersilab. The highest contamination of enterococci was observed for minced pork meat but most of the E. faecium was isolated from meatball-type frozen pork meat products (FP). Incidences of antimicrobial-resistant E. faecium against erythromycin, clindamycin and nitrofurantoin were 80%, 50% and 20%, respectively. No vancomycin-resistant enterococci were analyzed. Rep-PCR showed distinctive clusters with a similarity ≥ 98%, consisting of 18 E. faecium isolates from FP manufactured in seven companies. The analyzed data on the contamination and antimicrobial resistance patterns combined with molecular typing can be useful to derive risk management of antimicrobial-resistant enterococci in food.

Antimicrobial-Resistant Enterococcus faecium and Enterococcus faecalis Isolated From Healthy Thoroughbred Racehorses in Japan

In this study, the occurrence of antimicrobial-resistant (AMR) enterococci was evaluated in Thoroughbred (TB) racehorses in Japan. Fecal samples were collected from 212 healthy TB racehorses at the Miho and Ritto Training Centers of the Japan Racing Association from March 2017 to August 2018. Isolation and identification were performed by enterococcus selective medium and confirmed to the species using MALDI-TOF MS. Enterococcus faecium and E. faecalis isolates were subjected to antimicrobial susceptibility test against 11 antimicrobials by minimum inhibitory concentration based on recommendation from Clinical and Laboratory Standards Institute guidelines. Among 583 enterococcus isolates, E. faecium and E. faecalis were identified for 48.2% (281/583) and 7.4% (43/583), respectively. One isolate that was representing E. faecium (153 isolates) and E. faecalis (31 isolates) from each sample was selected for antimicrobial susceptibility test. The highest rate of resistance for E. faecium isolates was observed against enrofloxacin (57.5%; 88/153), followed by streptomycin (32.0%; 49/153), kanamycin (18.3%; 28/153), gentamycin (5.9%; 9/153), erythromycin (5.9%; 9/153), and oxytetracycline (4.6%; 7/153). For E. faecium isolates, the highest resistance was observed against streptomycin (90.3%; 28/31), followed by kanamycin (41.9%; 13/31), gentamycin (29.0%; 9/31), lincomycin (9.7%; 3/31), oxytetracycline (6.5%; 2/31), erythromycin (6.5%; 2/31), tylosin (6.5%; 2/31), enrofloxacin (6.5%; 2/31), and chloramphenicol (3.2%; 1/31). The results indicated that enrofloxacin and aminoglycosides were highly resistant among tested antimicrobials. Continuous monitoring studies are useful to increase the awareness of the potential for AMR bacteria to arise from imprudent use of antimicrobials in TB racehorses in Japan.

Quantifying Human Health Risks from Virginiamycin Use in Food Animals in China

Virginiamycin (VM), a streptogramin antibiotic, has been used to promote healthy growth and treat illnesses in farm animals in the United States and other countries. The combination streptogramin Quinupristin-Dalfopristin (QD) was approved in the United States in 1999 for treating patients with vancomycin-resistant Enterococcus faecium (VREF) infections. Many chickens and swine test positive for QD-resistant E. faecium, raising concerns that using VM in food animals might select for streptogramin-resistant strains of E. faecium that could compromise QD effectiveness in treating human VREF infections. Such concerns have prompted bans and phase-outs of VM as growth promoters in the United States and Europe. This study quantitatively estimates potential human health risks from QD-resistant VREF infections due to VM use in food animals in China. Plausible conservative (risk-maximizing) quantitative risk estimates are derived for future uses, assuming 100% resistance to linezolid and daptomycin and 100% prescription rate of QD to high-level (VanA) VREF-infected patients. Up to one shortened life every few decades to every few thousand years might occur in China from VM use in animals, although the most likely risk is zero (e.g., if resistance is not transferred from bacteria in food animals to bacteria infecting human patients). Sensitivity and probabilistic uncertainty analyses suggest that this conclusion is robust to several data gaps and uncertainties. Potential future human health risks from VM use in animals in China appear to be small or zero, even if QD is eventually approved for use in human patients.

Genetic characterization of high-level aminoglycoside-resistant Enterococcus faecalis and Enterococcus faecium isolated from retail chicken meat

Retail chicken meat can play a role in the transfer of drug resistance to humans through the handling or ingestion of improperly cooked meat contaminated with resistant enterococci. In fact, high-level aminoglycoside-resistance (HLAR) in enterococci identified in human cases. Therefore, the prevalence and genetic characterization of HLAR in enterococci in retail chicken meat were investigated in this study. Of the 345 enterococci strains, 29 (8.7%) showed HLAR. All HLAR in enterococci carried at least 1 of 2 aminoglycoside-modifying enzyme genes, aac(6')Ie-aph(2″)-Ia and ant(6)-Ia. Among the 13 isolates that carried aac(6')Ie-aph(2″)-Ia, 3 had pattern A, with IS256 at both ends, and the other 10 had pattern D, without IS256 at both ends. All HLAR in enterococci also showed multidrug resistance. Among the 24 erythromycin-resistant enterococci, 19 (79.2%) harbored the ermB gene, and one (4.2%) harbored both the ermB and ermA genes. A total of 21 enterococci were tetracycline-resistant and harbored one or more of the following tetracycline resistance genes tet(M), tet(L), and tet(O). The Int-Tn gene was detected in one isolate (3.4%) carrying the tet(M) and ermB genes. All 4 chloramphenicol-resistant isolates carried either the phenicol resistance gene cfr alone (one isolate), both cfr and fexA (one isolate), or both fexA and optrA (2 isolates). Four efflux pump genes, efr(A), efr(B), emeA, and lsa, were detected in all HLAR in Enterococcus faecalis isolates. These results improve our understanding of the transmission dynamics of HLAR in enterococci from non-hospital sources to humans.

Comparative analysis of Enterococcus faecalis and Enterococcus faecium strains isolated from clinical samples and traditional cheese types in the Northwest of Iran: antimicrobial susceptibility and virulence traits

This research was conducted using 50 samples of popular traditional cheeses and 160 enterococcal clinical isolates. Phenotypic and genotypic methods used for identification of enterococci. Then, the incidences of antibacterial resistance and virulence traits were investigated. In total, 165 E. faecalis and 43 E. faecium obtained from traditional cheeses and different clinical isolates were analyzed in the study. Antibiotic susceptibility testing revealed 175(84.1%) isolates with multi-drug resistance (MDR) patterns, which was more common among clinical sources. The predominant virulence profile, including gelE, asa1 and cpd was detected within 47 (22.6%) of the MDR isolates. Our results showed that traditional cheeses and clinical E. faecalis isolates have distinct patterns of virulence traits. The identified enterococci with antibiotic resistance and associated virulence factors, could provide a potential risk to the public health.

Occurrence of enterococci harbouring clinically important antibiotic resistance genes in the aquatic environment in Gauteng, South Africa

The development of antibiotic resistance and dissemination of its determinants is an emerging public health problem as it compromises treatment options of infections that were, until recently, treatable. Investigation of outbreaks of vancomycin resistant enterococci (VRE) suggests that the environment serves as a significant reservoir for antibiotic resistance genes (ARGs). However, there is a paucity of data regarding the presence of ARGs in the water sources in South Africa. In this study, water samples collected from wastewater treatment plants (WWTPs), surface water and hospital sewage were screened for enterococci harbouring genes conferring resistance to four classes of antibiotics. Enterococci isolates harbouring ARGs were detected in raw influent and treated wastewater discharge from WWTPs and hospital sewage water. Plasmid and transposon encoded ermB (macrolide), tetM and tetL (tetracycline) as well as aph(3')-IIIa (aminoglycosides) genes were frequently detected among the isolates, especially in E. faecalis. The presence of enterococci harbouring ARGs in the treated wastewater suggest that ARGs are discharged into the environment where their proliferation could be perpetuated. Among the enterococci clonal complexes (CCs) recovered from wastewater were E. faecium CC17 (ST18), which is frequently associated with hospital outbreaks and a novel E. faecalis sequence type (ST), ST780.

Characteristics of High-Level Ciprofloxacin-Resistant Enterococcus faecalis and Enterococcus faecium from Retail Chicken Meat in Korea

Genes encoding ciprofloxacin resistance in enterococci in animals may be transferred to bacteria in the animal gut and to zoonotic bacteria where they could pose a human health hazard. The objective of this study was to characterize antimicrobial resistance in high-level ciprofloxacin-resistant (HLCR) Enterococcus faecalis and Enterococcus faecium isolated from retail chicken meat. A total of 345 enterococci (335 E. faecalis and 10 E. faecium) were isolated from 200 chicken meat samples. Of these, 85 E. faecalis isolates and 1 E. faecium isolate were confirmed as HLCR enterococci. All 86 HLCR enterococci displayed gyrA- parC point mutations consisting of S83I-S80I (94.2%, 81 isolates), S83F-S80I (2.3%, 2 isolates), S83Y-S80I (2.3%, 2 isolates), and S83Y-S80F (1.2%, 1 isolate). Sixty-one (72.9%) of the 86 HLCR enterococci showed multidrug resistance to three to six classes of antimicrobial agents. Multilocus sequence typing revealed that E. faecalis had 17 different sequence types (ST) and E. faecium had 1 different ST, with ST256 observed most often (44 isolates, 51.8%). Although these results cannot exclude the possibility that pathotypes of enterococci isolated from chicken might represent transmission to or from humans, the foodborne HLCR E. faecalis indicated that the food chain is a potential route of enterococcal infection in humans.

Comparison of the loads and antibiotic-resistance profiles of Enterococcus species from conventional and organic chicken carcasses in South Korea

Antibiotic-resistant bacteria in poultry meat are a threat to public health. In this study, we compared the Enterococcus spp. loads and antibiotic-resistance profiles between carcasses of conventionally and organically raised chickens. A total of 144 chicken carcasses (72 conventional and 72 organic) was collected from local retail markets in Seoul, South Korea. Overall, 77.7% (112 of 144; 75% conventional and 80% organic) of chicken carcasses were positive for Enterococcus. The mean loads of Enterococcus spp. were greater in conventional chicken carcasses, at 2.9 ± 0.4 log CFU/mL, than those in organic chicken carcasses, at 1.78 ± 0.3 log CFU/mL (p < 0.05). A total of 104 isolates (52 from conventional and 52 from organic chicken carcasses) was randomly selected for further analysis. The predominant species was Enterococcus faecalis in both conventional and organic chicken carcasses (57.7 and 76.9%, respectively; P > 0.05). Rates of resistance to ciprofloxacin and erythromycin, which are used in veterinary medicine in South Korea, were significantly higher in conventional chicken carcasses than in organic chicken carcasses. However, we found no difference between the rates of resistance to antibiotics such as vancomycin and tigecycline, which were not registered for use in veterinary medicine in South Korea, of Enterococcus isolates from conventional and organic chicken carcasses. In addition, although multidrug resistant isolates were obtained from both types of chicken samples, the prevalence of samples positive for Enterococcus was significantly higher in conventional chicken carcasses than in organic chicken carcasses (P < 0.05). The most common multidrug resistance pattern was erythromycin-tetracycline-rifampicin in conventional chicken carcasses and quinupristin-dalfopristin-tetracycline-rifampicin in organic chicken carcasses. A high level of gentamicin resistance was observed in isolates from not only conventional (5.8%) but also organic chicken (1.9%) carcasses, with no significant difference in rates between them (P > 0.05). Despite this, our results suggest that organic food certification is effective in reducing fecal contamination and the burden of antibiotic-resistant Enterococcus spp. in chicken carcasses.

Prevalence of virulence genes in Enterococcus species isolated from companion animals and livestock

Enterococcus species have developed from being commensal bacteria to leading pathogens that cause infections in humans and animals. The gastrointestinal tract of mammals is the normal habitat of these species. Virulence factors are proteins that are produced by the bacterium which are used to enhance their pathogenicity. The objectives of this study were to isolate Enterococcus spp. from livestock and companion animals, differentiate between the different sub-species and detect the presence of important virulence genes. Rectal and saliva swabs were collected from dogs and cats, whereas only rectal swabs were collected from cattle and cloacal swabs from chickens. Presumptive Enterococcus was selected using Bile Esculin Azide (BEA) agar, and Enterococcus species were confirmed using the polymerase chain reaction (PCR) by amplifying the tuf gene. In order to differentiate between E. faecalis and E. faecium, a multiplex PCR was used to detect the SodA gene. The genes responsible for gelatinase production (gelE) and for conjugation (ccf) were also detected using PCR. Out of 211 animal swabs, 182 (86%) were positive for the tuf gene. Overall, there were 55 isolates of E. faecalis (30%) compared to 22 isolates of E. faecium (12%). The virulence genes had a prevalence of 52% and 36% for gelE and ccf, respectively, in all animal hosts. The results demonstrated that chicken cloacal samples had the highest prevalence for E. faecalis, gelE and ccf genes compared to all the other isolates detected from other animal hosts. The results also demonstrated a statistically significant (p < 0.05) association between the prevalence of virulence genes (gelE and ccf) and animal species from which Enterococcus spp. was isolated. We provided evidence that healthy livestock and companion animals can harbour pathogenic Enterococcus that can be transferred via the food chain as well as through close association such as petting and licking of humans. This study partially demonstrated that Enterococci spp. are capable of evolving from being simple commensal bacteria to becoming pathogens that cause infection in humans and animals through the acquisition of virulence factors through mobile genetic elements.

An Investigation of Enterococcus Species Isolated from the African Buffalo (Syncerus caffer) in Serengeti National Park, Tanzania

We isolated Enterococcus species that colonized in the African buffalo (Syncerus caffer) in order to investigate their genetic relatedness and antimicrobial susceptibility. A total of 219 isolates were obtained and a 16S rRNA gene sequence analysis showed they were classified into Enterococcus avium, E. casseliflavus, E. faecalis, E. faecium, E. hirae, or E. mundtii. Multilocus sequence typing of E. faecalis and E. faecium isolates indicated that some of the isolates showed an evolutionary distance that was far from the primary founders. The antimicrobial susceptibility of the enterococcal isolates suggested that the significant transmission of antimicrobial resistance via human intervention had not yet occurred.

Antimicrobial resistance and virulence profile of enterococci isolated from poultry and cattle sources in Nigeria

This study investigated the occurrence, antimicrobial resistance and virulence of Enterococcus from poultry and cattle farms. Three hundred and ninety samples: cloacal/rectal swabs (n = 260) and manure (n = 130] were processed for recovery of Enterococcus species. Standard bacteriological methods were used to isolate, identify and characterize Enterococcus species for antimicrobial susceptibility and expression of virulence traits. Detection of antibiotic resistance and virulence genes was carried out by polymerase chain reaction. Enterococcus was recovered from 167 (42.8%) of the 390 samples tested with a predominance of Enterococcus faecium (27.7%). Other species detected were Enterococcus gallinarum, Enterococcus faecalis, Enterococcus hirae, Enterococcus raffinosus, Enterococcus avium, Enterococcus casseliflavus, Enterococcus mundtii and Enterococcus durans. All the isolates tested were susceptible to vancomycin, but resistance to tetracycline, erythromycin, ampicillin and gentamicin was also observed among 61.0, 61.0, 45.1 and 32.7% of the isolates, respectively. Sixty (53.1%) of the isolates were multidrug resistant presenting as 24 different resistance patterns with resistance to gentamicin-erythromycin-streptomycin-tetracycline (CN-ERY-STR-TET) being the most common (n = 11) pattern. In addition to expression of virulence traits (haemolysin, gelatinase, biofilm production), antibiotic resistance (tetK, tetL, tetM, tetO and ermB) and virulence (asa1, gelE, cylA) genes were detected among the isolates. Also, in vitro transfer of resistance determinants was observed among 75% of the isolates tested. Our data revealed poultry, cattle and manure in this area are hosts to varying Enterococcus species harbouring virulence and resistance determinants that can be transferred to other organisms and also are important for causing nosocomial infection.

Antimicrobial resistance and virulence profiles of Enterococcus spp. isolated from horses in korea

Antimicrobial-resistant (AR) enterococci have emerged as leading nosocomial pathogens. Transmission of AR Enterococci from animals to humans has been demonstrated. However, there is limited information on the transmission of enterococci from horses to humans. To address this issue, we characterized 260 enterococci isolated from horse-associated samples in Korea in 2013 based on their AR profiles and virulence traits. AR profiling revealed an average ratio of AR enterococci of 23.8%. Seven isolates (2.7%) were multidrug-resistant Enterococcus faecalis. Most tetracycline-resistant enterococci harbored either tetM or tetL or both genes; genes conferring resistance to other antimicrobials were detected at low rates. Biofilm formation and gelatinase activity were observed in 51.1% and 47.7% of isolates, respectively; most were E. faecalis harboring the gelE gene. Evidence of transmission of AR enterococci between horses and their environments was provided by pulsed-field gel electrophoresis, and highlights the risk of AR enterococcus transmission to horse riders and handlers through close contact.

Virulence Genes among Enterococcus faecalis and Enterococcus faecium Isolated from Coastal Beaches and Human and Nonhuman Sources in Southern California and Puerto Rico

Most Enterococcus faecalis and E. faecium are harmless to humans; however, strains harboring virulence genes, including esp, gelE, cylA, asa1, and hyl, have been associated with human infections. E. faecalis and E. faecium are present in beach waters worldwide, yet little is known about their virulence potential. Here, multiplex PCR was used to compare the distribution of virulence genes among E. faecalis and E. faecium isolated from beaches in Southern California and Puerto Rico to isolates from potential sources including humans, animals, birds, and plants. All five virulence genes were found in E. faecalis and E. faecium from beach water, mostly among E. faecalis. gelE was the most common among isolates from all source types. There was a lower incidence of asa1, esp, cylA, and hyl genes among isolates from beach water, sewage, septage, urban runoff, sea wrack, and eelgrass as compared to human isolates, indicating that virulent strains of E. faecalis and E. faecium may not be widely disseminated at beaches. A higher frequency of asa1 and esp among E. faecalis from dogs and of asa1 among birds (mostly seagull) suggests that further studies on the distribution and virulence potential of strains carrying these genes may be warranted.

Antimicrobial resistance pattern and genetic correlation in Enterococcus faecium isolated from healthy volunteers

Enterococci are known as a cause of nosocomial infections and this aptitude is intensified by the growth of antibiotic resistance. In the present study, Enterococcus faecium isolates from healthy volunteers were considered to determine the antibiotic resistance profiles and genetic correlation. A total 91 normal flora isolates of enterococci were included in this study. Identification of Enterococcus genus and species were done by biochemical and PCR methods, respectively. Sensitivity for 10 antibiotics was determined and genetic relatedness of all isolates was assessed using Repetitive Element Palindromic PCR (REP-PCR) followed by Pulse Field Gel Electrophoresis (PFGE) on the representative patterns. None of the isolates were resistant to teicoplanin, vancomycin, quinupristin-dalfopristin, linezolid, chloramphenicol, ampicillin and high-level gentamicin. On the other hand, the resistance rate was detected in 30.7%, 23%, and 3.29% of isolates for erythromycin, tetracycline and ciprofloxacin, respectively. The results of PFGE showed 19 (61.5% of our isolates) common types (CT) and 35 (38.5%) single types (ST) amongst the isolates. This is the first study to describe antibiotic resistance pattern and genetic relationship among normal flora enterococci in Iran. This study showed no prevalence of Vancomycin Resistant Enterococci (VRE) and high degrees of diversity among normal flora isolates by genotyping using PFGE.

Prevalence of antimicrobial resistance in faecal enterococci from vet-visiting pets and assessment of risk factors

The objective of this study was to determine the prevalence of antimicrobial resistance (AMR) exhibited by enterococci isolated from faeces of pets and its underlying risk factors. From September 2009 to May 2012, rectal swabs were collected from 74 dogs and 17 cats, selected from the population of animals visiting the Veterinary Hospital of University of Porto, UPVet, through a systematic random procedure. Animal owners answered a questionnaire about the risk factors that could influence the presence of AMR in faecal enterococci. Enterococci isolation, identification and antimicrobial (AM) susceptibility testing were performed. Data analyses of multilevel, univariable and multivariable generalised linear mixed models were conducted. From all enterococci isolated (n=315), 61 per cent were considered multidrug-resistant, whereas only 9.2 per cent were susceptible to all AMs tested. Highest resistance was found to tetracycline (67.0 per cent), rifampicin (60.3 per cent), azithromycin (58.4 per cent), quinupristin/dalfopristin (54.0 per cent) and erythromycin (53.0 per cent). Previous fluoroquinolone treatments and coprophagic habits were the features more consistently associated with the presence of AMR for three (chloramphenicol, ciprofloxacin and azithromycin) and seven (tetracycline, rifampicin, gentamicin, chloramphenicol, ciprofloxacin, erythromycin and azithromycin), respectively, out of nine AMs assessed. Evaluating risk factors that determine the presence of drug-resistant bacteria in pets, a possible source of resistance determinants to human beings, is crucial for the selection of appropriate treatment guidelines by veterinary practitioners.

Molecular characterization of vancomycin-resistant Enterococcus faecium strains isolated from carriage and clinical samples in a tertiary hospital, Turkey

This study aimed to determine the presence of vancomycin resistance (vanA and vanB) and virulence genes (esp, asa1, gelE, ace, hyl, cylA, cpd and ebpA) in vancomycin-resistant Enterococcus faecium (VREfm) strains and to analyse the clonal relationships among the strains. E. faecium strains were identified from rectal and clinical specimens by biochemical tests and the API-20 Strep kit. Susceptibility testing was performed using disc-diffusion and broth-dilution methods. PFGE was used for molecular typing of the VREfm strains. The vancomycin resistance and virulence genes were amplified by two-step multiplex PCR. All 55 VREfm isolates were resistant to penicillin G, ampicillin and high-level gentamicin but were susceptible to quinupristin/dalfopristin and linezolid. Multiplex PCR analysis indicated that all isolates harboured vanA and that 41 (75 %) were positive for virulence genes. The esp gene was the most common virulence factor and was detected in nine (41 %) invasive and 32 (96.7 %) non-invasive isolates. Multiple virulence genes were observed only in two non-invasive isolates; one harboured esp and ebpA and the other harboured esp, ebpA, asa1, gelE and cpd. PFGE typing yielded 16 different types, seven of which were clusters with two to 14 strains each. The clustering rates of the rectal swab, blood and urine isolates were 72.7 %, 61.5 % and 87.5 %, respectively. The genetic similarity observed among the VREfm isolates indicated cross-transmission in the hospital. Further studies on the virulence factors present in the strains might provide insight into the acquisition of these traits and their contribution to increased prevalence of VREfm.

Co-colonization of vanA and vanB Enterococcus faecium of clonal complex 17 in a patient with bacteremia due to vanA E. faecium

A 53-year-old Vietnamese man with liver cirrhosis was transferred from a Vietnamese hospital to our tertiary care hospital in Korea in order to undergo a liver transplantation. Bacteremia due to vanA Enterococcus faecium was diagnosed, and stool surveillance cultures for vancomycin-resistant enterococci (VRE) were positive for both vanA and vanB E. faecium. Pulsed-field gel electrophoresis analysis revealed that the 2 vanA VRE isolates from the blood and stool were clonal, but the vanB VRE was unrelated to the vanA VRE. vanA and vanB VRE were ST64 and ST18, single-allele variations of clonal complex 17, respectively. This is the first case report of vanA VRE bacteremia in a Vietnamese patient and demonstrates the reemergence of vanB VRE since a single outbreak occurred 15years ago in Korea. The reemergence of vanB VRE emphasizes the importance of VRE genotyping to prevent the spread of new VRE strains.

Prevalence and characterization of Staphylococcus aureus and Staphylococcus pseudintermedius isolated from companion animals and environment in the veterinary teaching hospital in Zambia, Africa

The Republic of Zambia consists of only one veterinary teaching school at the University of Zambia (UNZA) where students and veterinarians are exposed to many bacterial pathogens including Staphylococcus aureus (SA) and Staphylococcus pseudintermedius (SP). The aim of this study was the characterization and antimicrobial susceptibility profile of eleven SA and 48 SP isolates from the veterinary hospitals' in- and outpatients and the environment. No isolate was resistant to cefoxitin by disk diffusion test and the corresponding resistance gene mecA was not found. In contrast, the resistance rates of SA to penicillin (63.6%) and trimethoprim-sulfamethoxazole (36.4%) and SP to penicillin (52.1%) and tetracycline (25.0%) were the highest. A variety of sequence types (STs) without a predominant type including numerous novel types were determined, especially for SP (39.6%). The spa typing provided a clonal assignment for all SAs (100%) and 24 SPs (50%) with three and two novel types, respectively. This study has provided an overview of SA and SP in the veterinary teaching hospital at UNZA. However, for a better understanding of these species regarding pathogenesis and transmission, further studies on the prevalence and characterization of SA and SP from veterinary staff, pet owners, and farm animals in Zambia is needed.

High-level aminoglycoside resistance and virulence characteristics among Enterococci isolated from recreational beaches in Malaysia

We report the first study on the occurrence of high-level aminoglycoside-resistant (HLAR) Enterococci in coastal bathing waters and beach sand in Malaysia. None of the encountered isolates were resistant to high levels of gentamicin (500 μg/mL). However, high-level resistance to kanamycin (2,000 μg/mL) was observed in 14.2 % of tested isolates, the highest proportions observed being among beach sand isolates. High-level resistance to kanamycin was higher among Enterococcus faecalis and Enterococcus faecium than Enterococcus spp. Chi-square analysis showed no significant association between responses to tested antibiotics and the species allocation or source of isolation of all tested Enterococci. The species classification of encountered Enterococci resistance to vancomycin was highest among Enterococcus spp. (5.89 %) followed by E. faecium (4.785) and least among E. faecalis. A total of 160 isolates were also tested for virulence characteristics. On the whole, caseinase production was profoundly highest (15.01 %) while the least prevalent virulence characteristic observed among tested beach Enterococci was haemolysis of rabbit blood (3.65 %). A strong association was observed between the source of isolation and responses for each of caseinase (C = 0.47, V = 0.53) and slime (C = 0.50, V = 0.58) assays. Analysis of obtained spearman's coefficient showed a strong correlation between caseinase and each of the slime production (p = 0.04), gelatinase (p = 0.0035) and haemolytic activity on horse blood (p = 0.004), respectively. Suggestively, these are the main virulent characteristics of the studied beach Enterococci. Our findings suggest that recreational beaches may contribute to the dissemination of Enterococci with HLAR and virulence characteristics.