Evaluation of screening algorithms to detect rectal colonization with carbapenemase-producing Enterobacterales in a resource-limited setting.

Objectives: To improve and rationalize the detection of carbapenemase-producing Enterobacterales (CPE) in rectal swabs in a high-prevalence and resource-constrained setting, addressing surveillance challenges typically encountered in laboratories with limited resources. Methods: A point prevalence survey (PPS) was conducted on 15 August 2022, in a provincial children's hospital in northern Vietnam. Rectal swab samples of all admitted children were collected and plated on a selective medium for carbapenem-resistant Enterobacterales (CRE). Species identification and antimicrobial susceptibility testing (AST) were performed by MALDI-TOF, and VITEK2 XL and interpreted according to CLSI breakpoints (2022). Carbapenemases were detected by the carbapenem inactivation method (CIM) and quantitative real-time PCR (qRT-PCR). Results: Rectal swab samples were obtained from 376 patients. Of 178 isolates growing on the CRE screening agar, 140 isolates were confirmed as Enterobacterales of which 118 (84.3%) isolates were resistant to meropenem and/or ertapenem. CIM and PCR showed that 90/118 (76.3%) were carbapenemase producers. Overall, 83/367 (22.6%) were colonized by CPE. Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae complex were the most common CPE detected, with NDM as the predominant carbapenemase (78/90; 86.7%). Phenotypic resistance to meropenem was the best predictor of CPE production (sensitivity 85.6%, specificity 100%) compared with ertapenem resistance (95.6% sensitivity, 36% specificity). CIM was 100% concordant with PCR in detecting carbapenemases. Conclusions: These findings underscore the effectiveness of meropenem resistance as a robust indicator of the production of carbapenemases and the reliability of the CIM method to detect such carbapenemases in resource-limited settings where the performance of molecular methods is not possible.

Fluoroquinolone-resistant Escherichia coli among the rectal flora is the predominant risk factor for severe infection after transrectal ultrasound-guided prostate biopsy: a prospective observational study.

BACKGROUND: Infection of the prostate gland following biopsy, usually with Escherichia coli, is a common complication, despite the use of antimicrobial prophylaxis. A fluoroquinolone (FQ) is commonly prescribed as prophylaxis. Worryingly, the rate of fluoroquinolone-resistant (FQ-R) E. coli species has been shown to be increasing. OBJECTIVE: This study aimed to identify risk factors associated with infection after transrectal ultrasound-guided prostate biopsy (TRUS-Bx). METHODS: This was a prospective study on patients undergoing TRUS-Bx in southeast Sweden. Prebiopsy rectal and urine cultures were obtained, and antimicrobial susceptibility and risk-group stratification were determined. Multivariate analyses were performed to identify independent risk factors for post-biopsy urinary tract infection (UTI) and FQ-R E. coli in the rectal flora. RESULTS: In all, 283 patients were included, of whom 18 (6.4%) developed post-TRUS-Bx UTIs. Of these, 10 (3.5%) had an UTI without systemic inflammatory response syndrome (SIRS) and 8 (2.8%) had a UTI with SIRS. Being in the medium- or high-risk groups of infectious complications was not an independent risk factor for UTI with SIRS after TRUS-Bx, but low-level FQ-resistance (minimum inhibitory concentration (MIC): 0.125-0.25 mg/L) or FQ-resistance (MIC > 0.5 mg/L) among E. coli in the faecal flora was. Risk for SIRS increased in parallel with increasing degrees of FQ-resistance. Significant risk factor for harbouring FQ-R E.coli was travelling outside Europe within the previous 12 months. CONCLUSION: The predominant risk factor for UTI with SIRS after TRUS-Bx was FQ-R E. coli among the faecal flora. The difficulty in identifying this type of risk factor demonstrates a need for studies on the development of a general approach either with rectal swab culture for targeted prophylaxis, or prior rectal preparation with a bactericidal agent such as povidone-iodine before TRUS-Bx to reduce the risk of FQ-R E. coli-related infection.

Rapid increase in occurrence of carbapenem-resistant Enterobacteriaceae in healthy rural residents in Shandong Province, China, from 2015 to 2017.

OBJECTIVES: The global increase in carbapenem-resistant Enterobacteriaceae (CRE) is a growing health concern. Infections caused by CRE are associated with increased mortality and length of hospital stay, emphasising the health and economic burden posed by these pathogens. Although CRE can inhabit the human gut asymptomatically, colonisation with CRE is associated with an increased risk of CRE infection and mortality. In this study, we investigated the occurrence and characteristics of CRE in faecal samples from healthy persons in 12 villages in Shandong Province, China. METHODS: Screening for CRE in faecal samples was performed by selective cultivation. Minimum inhibitory concentrations (MICs) of meropenem were determined by the agar dilution method. Multilocus sequence typing (MLST) and carbapenemase gene carriage of the isolates were determined by whole-genome sequencing. Genetic relatedness of Escherichia coli isolates was determined by core genome MLST. RESULTS: CRE carriage increased from 2.4% in 2015 to 13.4% in 2017. Most CRE isolates (93.0%) were E. coli and all carried NDM-type carbapenemases. Sequence types (STs) among the E. coli isolates were diverse. The single most common ST was the highly epidemic strain ST167, which was only observed in 2017. CONCLUSION: We report a rapid increase in occurrence of CRE (from 2.4% to 13.4%) among faecal samples collected from healthy rural residents of Shandong Province from 2015 to 2017. Colonisation with CRE is known to increase the risk of CRE infection, and the worrying deterioration of the epidemiological situation in the region reported here indicates a need for further monitoring and possible interventions.

High diversity of blaNDM-1-encoding plasmids in Klebsiella pneumoniae isolated from neonates in a Vietnamese hospital.

OBJECTIVES: The carbapenemase-encoding gene blaNDM-1 has been reported in Vietnam during the last 10 years, and blaNDM-producing Enterobacteriaceae are now silently and rapidly spreading. A key factor behind dissemination of blaNDM-1 is plasmids, mobile genetic elements that commonly carry antibiotic resistance genes and spread via conjugation. The diversity of blaNDM-1-encoding plasmids from neonates at a large Vietnamese hospital was characterized in this study. METHODS: 18 fecal Klebsiella pneumoniae and Klebsiella quasipneumoniae isolates collected from 16 neonates at a large pediatric hospital in Vietnam were studied using optical DNA mapping (ODM) and next-generation sequencing (NGS). Plasmids carrying the blaNDM-1 gene were identified by combining ODM with Cas9 restriction. The plasmids in the isolates were compared to investigate whether the same plasmid was present in different patients. RESULTS: Although the same plasmid was found in some isolates, ODM confirmed that there were at least 10 different plasmids encoding blaNDM-1 among the 18 isolates, thus indicating wide plasmid diversity. The ODM results concur with the NGS data. Interestingly, some isolates had two distinct plasmids encoding blaNDM-1 that could be readily identified with ODM. The coexistence of different plasmids carrying the same blaNDM-1 gene in a single isolate has rarely been reported, probably because of limitations in plasmid characterization techniques. CONCLUSIONS: The plasmids encoding the blaNDM-1 gene in this study cohort were diverse and may represent a similar picture in Vietnamese society. The study highlights important aspects of the usefulness of ODM for plasmid analysis.

Clonal spread of carbapenem-resistant Klebsiella pneumoniae among patients at admission and discharge at a Vietnamese neonatal intensive care unit.

BACKGROUND: The increasing prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is a growing problem globally, particularly in low- to middle-income countries (LMICs). Previous studies have shown high rates of CRE colonisation among patients at hospitals in LMICs, with increased risk of hospital-acquired infections. METHODS: We isolated carbapenem-resistant Klebsiella pneumoniae (CRKP) from faecal samples collected in 2017 from patients at admission and discharge at a Vietnamese neonatal intensive care unit (NICU). 126 CRKP were whole-genome sequenced. The phylogenetic relationship between the isolates and between clinical CRKP isolates collected in 2012-2018 at the same hospital were investigated. RESULTS: NDM-type carbapenemase-(61%) and KPC-2-encoding genes (41%) were the most common carbapenem resistance genes observed among the admission and discharge isolates. Most isolates (56%) belonged to three distinct clonal clusters of ST15, carrying blaKPC-2, blaNDM-1 and blaNDM-4, respectively. Each cluster also comprised clinical isolates from blood collected at the study hospital. The most dominant ST15 clone was shown to be related to isolates collected from the same hospital as far back as in 2012. CONCLUSIONS: Highly resistant CRKP were found colonising admission and discharge patients at a Vietnamese NICU, emphasising the importance of continued monitoring. Whole-genome sequencing revealed a population of CRKP consisting mostly of ST15 isolates in three clonally related clusters, each related to blood isolates collected from the same hospital. Furthermore, clinical isolates collected from previous years (dating back to 2012) were shown to likely be clonally descended from ST15 isolates in the largest cluster, suggesting a successful hospital strain which can colonise inpatients.

Dissemination of blaNDM-5 via IncX3 plasmids in carbapenem-resistant Enterobacteriaceae among humans and in the environment in an intensive vegetable cultivation area in eastern China.

The environment of a large-scale vegetable production area can be exposed to antibiotic residues and antibiotic-resistant bacteria (ARB) via animal manure and irrigation with contaminated water, which can facilitate the dissemination of ARB. However, the occurrence of ARB in plantation areas and their dissemination in this environment remain largely unexplored. In total, 382 samples including those from vegetable (n = 106), soil (n = 87), well water (n = 24), river water (n = 20), river sediments (n = 20), farmer feces (n = 58) and farmer hands (n = 67) were collected in 2019 from a large-scale cultivation area in Shandong, China. Selective agar plates were used to screen for carbapenem-resistant Enterobacteriaceae (CRE) and whole-genome sequencing and Southern blotting were used to characterise isolates and mobile genetic elements carrying carbapenem resistance determinants. A total of nine NDM-5-producing isolates of Escherichia coli, Klebsiella pneumoniae, and Citrobacter spp. were identified from environmental sources and human feces, all of which were multidrug-resistant. Single nucleotide polymorphism analysis suggested clonal transmission of carbapenem-resistant Citrobacter sedlakii within greenhouse soils in the area. Eight of the isolates carried closely related or identical IncX3 plasmids carrying blaNDM-5, which were shown to be conjugative via filter mating experiments, indicating the highly transmissible nature of this genetic element. Isolates of E. coli and Citrobacter freundii were detected in the feces of local farm workers and contained similar IncX3 plasmids with blaNDM-5 environmental isolates, suggesting a potential risk of CRE transfer from the work environment to the farm workers. Thus, further research is required to investigate the potential health risks associated with environmental exposure to CRE in vegetable cultivation areas.

Low incidence of antibiotic-resistant bacteria in south-east Sweden: An epidemiologic study on 9268 cases of bloodstream infection.

OBJECTIVES: The aim of this study was to investigate the epidemiology of bloodstream infections (BSI) in a Swedish setting, with focus on risk factors for BSI-associated mortality. METHODS: A 9-year (2008-2016) retrospective cohort study from electronic records of episodes of bacteremia amongst hospitalized patients in the county of Östergötland, Sweden was conducted. Data on episodes of BSI including microorganisms, antibiotic susceptibility, gender, age, hospital admissions, comorbidity, mortality and aggregated antimicrobial consumption (DDD /1,000 inhabitants/day) were collected and analyzed. Multidrug resistance (MDR) was defined as resistance to at least three groups of antibiotics. MDR bacteria and MRSA, ESBL-producing Enterobacteriaceae, vancomycin-resistant enterococci not fulfilling the MDR criteria were all defined as antimicrobial-resistant (AMR) bacteria and included in the statistical analysis of risk factors for mortality. RESULTS: In all, 9,268 cases of BSI were found. The overall 30-day all-cause mortality in the group of patients with BSI was 13%. The incidence of BSI and associated 30-day all-cause mortality per 100,000 hospital admissions increased by 66% and 17% respectively during the nine-year study period. The most common species were Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and Enterococcus faecalis. Independent risk factors for 30-day mortality were age (RR: 1.02 (CI: 1.02-1.03)) and 1, 2 or ≥3 comorbidities RR: 2.06 (CI: 1.68-2.52), 2.79 (CI: 2.27-3.42) and 2.82 (CI: 2.31-3.45) respectively. Almost 3% (n = 245) of all BSIs were caused by AMR bacteria increasing from 12 to 47 per 100,000 hospital admissions 2008-2016 (p = 0.01), but this was not associated with a corresponding increase in mortality risk (RR: 0.89 (CI: 0.81-0.97)). CONCLUSION: Comorbidity was the predominant risk factor for 30-day all-cause mortality associated with BSI in this study. The burden of AMR was low and not associated with increased mortality. Patients with BSIs caused by AMR bacteria (MDR, MRSA, ESBL and VRE) were younger, had fewer comorbidities, and the 30-day all-cause mortality was lower in this group.

Molecular and phenotypic characterization of clinical isolates belonging to a KPC-2-producing strain of ST15 Klebsiella pneumoniae from a Vietnamese pediatric hospital.

Background: Carbapenem-resistant Klebsiella pneumoniae are becoming increasingly common in hospital settings worldwide and are a source of increased morbidity, mortality and health care costs. The global epidemiology of carbapenem-resistant K. pneumoniae is characterized by different strains distributed geographically, with the strain ST258 being predominant in Europe and USA, and ST11 being most common in East Asia. ST15 is a less frequently occurring strain but has nevertheless been reported worldwide as a source of hospital outbreaks of carbapenem-resistant K. pneumoniae. Methods: In this study, whole-genome sequencing and antimicrobial susceptibility testing was used to characterize 57 clinical isolates of carbapenem-resistant K. pneumoniae belonging to a strain of ST15, which were collected at a Vietnamese pediatric hospital from February throughout September 2015. Results: Aside from the carbapenem resistance gene blaKPC-2, which was carried by all isolates, prevalence of resistance genes to other antibiotics including aminoglycosides, macrolides, quinolones, fosfomycin and trimethoprim, was also high. All isolates were multidrug-resistant. Susceptibility was highest to ceftazidime/avibactam (96%), gentamicin (91%) and tigecycline (82%). Notably, the colistin resistance rate was very high (42%). Single-nucleotide polymorphism analysis indicated that most isolates belonged to a single clone. Conclusions: The diverse variety of antibiotic resistance genes and the high antibiotic resistance rates to last-resort antibiotics such as carbapenems and colistin, is indicative of a highly adaptable strain. This emphasizes the importance of implementation of infection controls measures, continued monitoring of antibiotic resistance and prudent use of antibiotics to prevent further selection of resistant strains and the emergence of pan-resistant clones.

Inter-host Transmission of Carbapenemase-Producing Escherichia coli among Humans and Backyard Animals.

BACKGROUND: The rapidly increasing dissemination of carbapenem-resistant Enterobacteriaceae (CRE) in both humans and animals poses a global threat to public health. However, the transmission of CRE between humans and animals has not yet been well studied. OBJECTIVES: We investigated the prevalence, risk factors, and drivers of CRE transmission between humans and their backyard animals in rural China. METHODS: We conducted a comprehensive sampling strategy in 12 villages in Shandong, China. Using the household [residents and their backyard animals (farm and companion animals)] as a single surveillance unit, we assessed the prevalence of CRE at the household level and examined the factors associated with CRE carriage through a detailed questionnaire. Genetic relationships among human- and animal-derived CRE were assessed using whole-genome sequencing-based molecular methods. RESULTS: A total of 88 New Delhi metallo-ß-lactamases-type carbapenem-resistant Escherichia coli (NDM-EC), including 17 from humans, 44 from pigs, 12 from chickens, 1 from cattle, and 2 from dogs, were isolated from 65 of the 746 households examined. The remaining 12 NDM-EC were from flies in the immediate backyard environment. The NDM-EC colonization in households was significantly associated with a) the number of species of backyard animals raised/kept in the same household, and b) the use of human and/or animal feces as fertilizer. Discriminant analysis of principal components (DAPC) revealed that a large proportion of the core genomes of the NDM-EC belonged to strains from hosts other than their own, and several human isolates shared closely related core single-nucleotide polymorphisms and blaNDM genetic contexts with isolates from backyard animals. CONCLUSIONS: To our knowledge, we are the first to report evidence of direct transmission of NDM-EC between humans and animals. Given the rise of NDM-EC in community and hospital infections, combating NDM-EC transmission in backyard farm systems is needed. https://doi.org/10.1289/EHP5251.

Antimicrobial susceptibility testing and antibiotic consumption results from 16 hospitals in Viet Nam: The VINARES project 2012-2013.

OBJECTIVE: To establish a hospital-based surveillance network with national coverage for antimicrobial resistance (AMR) and antibiotic consumption in Viet Nam. METHODS: A 16-hospital network (Viet Nam Resistance: VINARES) was established and consisted of national and provincial-level hospitals across the country. Antimicrobial susceptibility testing results from routine clinical diagnostic specimens and antibiotic consumption data in Defined Daily Dose per 1000 bed days (DDD/1000 patient-days) were prospectively collected and analysed between October 2012 and September 2013. RESULTS: Data from a total of 24 732 de-duplicated clinical isolates were reported. The most common bacteria were: Escherichia coli (4437 isolates, 18%), Klebsiella spp. (3290 isolates, 13%) and Acinetobacter spp. (2895 isolates, 12%). The hospital average antibiotic consumption was 918 DDD/1000 patient-days. Third-generation cephalosporins were the most frequently used antibiotic class (223 DDD/1000 patient-days, 24%), followed by fluoroquinolones (151 DDD/1000 patient-days, 16%) and second-generation cephalosporins (112 DDD/1000 patient-days, 12%). Proportions of antibiotic resistance were high: 1098/1580 (69%) Staphylococcus aureus isolates were methicillin-resistant (MRSA); 115/344 isolates (33%) and 90/358 (25%) Streptococcus pneumoniae had reduced susceptibility to penicillin and ceftriaxone, respectively. A total of 180/2977 (6%) E. coli and 242/1526 (16%) Klebsiella pneumoniae were resistant to imipenem, respectively; 602/1826 (33%) Pseudomonas aeruginosa were resistant to ceftazidime and 578/1765 (33%) to imipenem. Of Acinetobacter spp. 1495/2138 (70%) were resistant to carbapenems and 2/333 (1%) to colistin. CONCLUSIONS: These data are valuable in providing a baseline for AMR among common bacterial pathogens in Vietnamese hospitals and to assess the impact of interventions.

Phenotypic screening for quinolone resistance in Escherichia coli.

Recent studies show that rectal colonization with low-level ciprofloxacin-resistant Escherichia coli (ciprofloxacin minimal inhibitory concentration (MIC) above the epidemiological cutoff point, but below the clinical breakpoint for resistance), i.e., in the range > 0.06-0.5 mg/L is an independent risk factor for febrile urinary tract infection after transrectal ultrasound-guided biopsy (TRUS-B) of the prostate, adding to the other risk posed by established ciprofloxacin resistance in E. coli (MIC > 0.5 mg/L) as currently defined. We aimed to identify the quinolone that by disk diffusion best discriminates phenotypic wild-type isolates (ciprofloxacin MIC ≤ 0.06 mg/L) of E. coli from isolates with acquired resistance, and to determine the resistance genotype of each isolate. The susceptibility of 108 E. coli isolates was evaluated by ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, and pefloxacin disk diffusion and correlated to ciprofloxacin MIC (broth microdilution) using EUCAST methodology. Genotypic resistance was identified by PCR and DNA sequencing. The specificity was 100% for all quinolone disks. Sensitivity varied substantially, as follows: ciprofloxacin 59%, levofloxacin 46%, moxifloxacin 59%, nalidixic acid 97%, and pefloxacin 97%. We suggest that in situations where low-level quinolone resistance might be of importance, such as when screening for quinolone resistance in fecal samples pre-TRUS-B, a pefloxacin (S ≥ 24 mm) or nalidixic acid (S ≥ 19 mm) disk, or a combination of the two, should be used. In a setting where plasmid-mediated resistance is prevalent, pefloxacin might perform better than nalidixic acid.

Dissemination of extended-spectrum ß-lactamase-producing Escherichia coli carrying mcr-1 among multiple environmental sources in rural China and associated risk to human health.

Antibiotic resistance among gram-negative bacteria is increasingly becoming a problem of global concern. Particularly problematic is the emergence of resistance to last-resort antibiotics such as carbapenems and colistin. The increasing number of reports on the plasmid-mediated colistin resistance gene mcr-1 in isolates worldwide is raising concerns for the future usefulness of this class of antibiotics. Dissemination of mcr-1 is believed to have originated mainly from animal breeding, however, the role of the environment as a transmission source is not yet fully understood. In the current study, 89 extended-spectrum ß-lactamase-producing Escherichia coli isolated from 231 samples from different environmental sources in 12 villages in a rural area of Shandong, China, were screened for mcr-1. 17 (19.1%) mcr-1-positive isolates were found from different environmental sources, aggregated in 6 villages. Plasmids of three different Inc-groups carrying mcr-1 were confirmed, indicating that the widespread geographical distribution of mcr-1 in the local area is due to a number of different plasmids. Additionally, almost a third (29.4%) of the isolates carried virulence factors associated to intestinal pathogenic E. coli. These results illustrate the high complexity of the transmission patterns of mcr-1 among different environmental matrices on a local scale and the potential for the environment to facilitate dissemination and emergence of antibiotic-resistant and virulent strains of bacteria.

High prevalence of colonisation with carbapenem-resistant Enterobacteriaceae among patients admitted to Vietnamese hospitals: Risk factors and burden of disease.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) is an increasing problem worldwide, but particularly problematic in low- and middle-income countries (LMIC) due to limitations of resources for surveillance of CRE and infection prevention and control (IPC). METHODS: A point prevalence survey (PPS) with screening for colonisation with CRE was conducted on 2233 patients admitted to neonatal, paediatric and adult care at 12 Vietnamese hospitals located in northern, central and southern Vietnam during 2017 and 2018. CRE colonisation was determined by culturing of faecal specimens on selective agar for CRE. Risk factors for CRE colonisation were evaluated. A CRE admission and discharge screening sub-study was conducted among one of the most vulnerable patient groups; infants treated at an 80-bed Neonatal ICU from March throughout June 2017 to assess CRE acquisition, hospital-acquired infection (HAI) and treatment outcome. RESULTS: A total of 1165 (52%) patients were colonised with CRE, most commonly Klebsiella pneumoniae (n = 805), Escherichia coli (n = 682) and Enterobacter spp. (n = 61). Duration of hospital stay, HAI and treatment with a carbapenem were independent risk factors for CRE colonisation. The PPS showed that the prevalence of CRE colonisation increased on average 4.2% per day and mean CRE colonisation rates increased from 13% on the day of admission to 89% at day 15 of hospital stay. At the NICU, CRE colonisation increased from 32% at admission to 87% at discharge, mortality was significantly associated (OR 5·5, P < 0·01) with CRE colonisation and HAI on admission. CONCLUSION: These data indicate that there is an epidemic spread of CRE in Vietnamese hospitals with rapid transmission to hospitalised patients.

Genomic analysis of Staphylococcus aureus along a pork production chain and in the community, Shandong Province, China.

Livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) is an increasingly important public health concern worldwide; however, data on LA-MRSA from Asian countries is scarce. As such, a comprehensive molecular epidemiological survey of S. aureus along a pork production chain and in the community was undertaken in Shandong Province, China. spa typing and whole-genome sequencing were used to survey the occurrence and potential transmission of S. aureus in various sectors, including 899 porcine samples (snout or skin swabs, carcass swabs and pork portions), 845 human nasal samples and 239 environmental samples from commercial farms, a slaughterhouse, a pork wholesale market and the surrounding community. MRSA was detected in higher frequencies in samples from two commercial pig farms (pigs, 49%; farm workers, 64%; environmental samples, 16%) than in samples from the slaughterhouse (fatteners, 8.2%; carcasses, 1.1%; operation workers, 0%; environmental samples, 3.8%), the pork wholesale market (pork, 14%; sellers, 0%) and individuals in the community (6.8%). There were significant differences in population structures, antimicrobial susceptibility profiles, and the presence of resistance and virulence genes between human- and pig-associated isolates. The phylogenetic analysis confirmed the dissemination of LA-MRSA between various segments along the pork production chain. However, MRSA of the same sequence type was not found to be disseminated between the commercial farms and the surrounding communities. Furthermore, one MRSA ST398 was observed, and a novel CC9 variant ST3597 was detected within the chain. The high MRSA carriage rates and the emergence of a new MRSA CC9 variant identified in this study highlight the need for MRSA surveillance.

Evaluating Dissemination Mechanisms of Antibiotic-Resistant Bacteria in Rural Environments in China by Using CTX-M-Producing Escherichia coli as an Indicator.

It is becoming increasingly recognized that the environment plays an important role both in the emergence and in dissemination of antibiotic-resistant bacteria (ARB), Mechanisms and factors facilitating this development are, however, not yet well understood. The high detection rate of CTX-M genes in environmental sources provides an opportunity to explore this issue. In this study, 88 CTX-M-producing Escherichia coli were isolated from 30 pig feces samples from 30 pig farms and 201 environmental samples. CTX-M-producing E. coli was detected with the following frequencies in the different types of samples: pig feces, 73%; river water, 64%; river sediment, 52%; wastewater, 31%; drinking water, 23%; outlet sediment, 21%; soil, 17%; and vegetables, 4.4%. Dissemination of CTX-M-producing E. coli to different environmental matrices was evaluated by analyzing the genetic relatedness of isolates from different environmental sources, and putative transmission routes through bird feces, pig feces, drinking water, river sediment, river water, and wastewater were hypothesized. Dissemination through these routes is likely facilitated by anthropogenic activities and environmental factors. Wild birds as potential vectors for dissemination of CTX-M-producing E. coli have the capacity to spread ARB across long distances. Regional dissemination between different environmental matrices of CTX-M-producing E. coli increases the exposure risk of humans and animals in the area.

Characterization of Clinically Relevant Strains of Extended-Spectrum ß-Lactamase-Producing Klebsiella pneumoniae Occurring in Environmental Sources in a Rural Area of China by Using Whole-Genome Sequencing.

Klebsiella pneumoniae is a gram-negative, opportunistic pathogen, and a common cause of healthcare-associated infections such as pneumonia, septicemia, and urinary tract infection. The purpose of this study was to survey the occurrence of and characterize K. pneumoniae in different environmental sources in a rural area of Shandong province, China. Two hundred and thirty-one samples from different environmental sources in 12 villages were screened for extended-spectrum ß-lactamase-(ESBL)-producing K. pneumoniae, and 14 (6%) samples were positive. All isolates were multidrug-resistant and a few of them belonged to clinically relevant strains which are known to cause hospital outbreaks worldwide. Serotypes, virulence genes, serum survival, and phagocytosis survival were analyzed and the results showed the presence of virulence factors associated with highly virulent clones and a high degree of phagocytosis survivability, indicating the potential virulence of these isolates. These results emphasize the need for further studies designed to elucidate the role of the environment in transmission and dissemination of ESBL-producing K. pneumoniae and the potential risk posed to human and environmental health.

Characterization of extended-spectrum ß-lactamase-producing Escherichia coli harboring mcr-1 and toxin genes from human fecal samples from China.

AIM: To characterize extended-spectrum ß-lactamase-producing Escherichia coli harboring the colistin resistance gene mcr-1 from human fecal samples collected in 2012 in a rural area of Shandong province, PR China. MATERIALS & METHODS: Whole-genome sequencing and antimicrobial susceptibility testing was performed on 25 mcr-1-positive isolates to determine carriage of antibiotic resistance and virulence genes, diversity and antibiotic resistance profiles. RESULTS: The isolates were highly genetically diverse and carried a large variety of different antibiotic resistance genes. The multidrug-resistance rate was high (96%). Virulence genes associated with intestinal pathogenic E. coli were carried by 32% of the isolates. CONCLUSION: Further monitoring of the epidemiological situation is necessary to ensure a preparedness for potential emergence of novel, difficult-to-treat strains and awareness of available treatment options.

Duration of travel-associated faecal colonisation with ESBL-producing Enterobacteriaceae - A one year follow-up study.

BACKGROUND: In a previous study, we found that 30% of individuals travelling outside Scandinavia acquired extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) in their faecal flora. The aim of this study was to determine the duration of travel-associated faecal colonisation with ESBL-PE, to assess risk factors for prolonged colonisation and to detect changes in antibiotic susceptibility during prolonged colonisation. METHODS: Individuals with travel-associated colonisation with ESBL-PE submitted faecal samples every 3rd month over a one-year period. A questionnaire was completed at the beginning and end of follow-up. All specimens were analysed for ESBL-PE, and all isolates underwent confirmatory phenotype testing as well as molecular characterisation of ESBL-genes. Minimum inhibitory concentrations (MIC) for beta-lactam and non-beta-lactam agents were determined using the Etest. RESULTS: Among 64 participants with travel-associated colonisation with ESBL-PE, sustained carriage was seen in 20/63 (32%), 16/63 (25%), 9/63 (14%) and 7/64 (11%) at 3, 6, 9 and 12 months after return from their journey, respectively. The majority, 44 (69%) of travellers were short-term carriers with ESBL-PE only detected in the initial post-travel stool sample. Evaluation of risk factors demonstrated a decreased risk of becoming a long-term carrier among travellers with diarrhoea while abroad and a history of a new journey during the follow-up period. High susceptible rates were demonstrated to carbapenems (97-100%), temocillin (95%), mecillinam (97%), amikacin (98%), fosfomycin (98%), nitrofurantoin (99%) and tigecycline (97%). CONCLUSION: Travel-associated faecal colonisation with ESBL-PE appears to be transient and generally brief. Diarrhoea while abroad or a new trip abroad during the follow-up period decreased the risk of becoming a long-term carrier. Only 11% of travellers who acquired ESBL-PE during their travels had sustained colonisation 12 months after return.

Mobile colistin resistance gene mcr-5 in porcine Aeromonas hydrophila.

Objectives: To characterize the mobile colistin resistance gene mcr-5 in Aeromonas hydrophila from backyard pigs in rural areas of China. Methods: Pig faecal samples from 194 households were directly tested for the presence of mcr-5 by PCR assay and the phenotypic antimicrobial susceptibility profiles of the mcr-5-positive isolates were determined using the broth dilution method. The genomic location and transferability of mcr-5 were analysed by S1-PFGE with Southern blotting and DNA hybridization, and natural transformation, respectively. One strain isolated from an mcr-5-positive sample was subjected to WGS and the stability of the mcr-5-harbouring plasmid over successive generations was examined by subculturing. Results: One mcr-5-positive A. hydrophila isolate showing resistance, with a colistin MIC of 4 mg/L, was isolated from a backyard pig faecal sample. mcr-5 was located on a 7915 bp plasmid designated pI064-2, which could naturally transform into a colistin-susceptible A. hydrophila strain of porcine origin and mediated colistin resistance in both the original isolate and its transformants. The plasmid backbone (3790 bp) of pI064-2 showed 81% nucleotide sequence identity to the corresponding region of the ColE2-type plasmid pAsa1 from Aeromonas salmonicida, while similar replication primases are widely distributed among aeromonads, Enterobacteriaceae and Pseudomonas species. Conclusions: To the best of our knowledge, this is the first identification of the novel colistin resistance gene mcr-5 in an A. hydrophila isolate from the faeces of a backyard pig. mcr-5 is expected to be able to disseminate among different bacterial species and genera.