Molecular studies on diarrhea-associated Escherichia coli isolated from humans and animals in Egypt

Exploring Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli in Food-Producing Animals and Animal-Derived Foods

Antimicrobials serve as crucial treatments in both veterinary and human medicine, aiding in the control and prevention of infectious diseases. However, their misuse or overuse has led to the emergence of antimicrobial resistance, posing a significant threat to public health. This review focuses on extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in animals and their associated food products, which contribute to the proliferation of antimicrobial-resistant strains. Recent research has highlighted the presence of ESBL-producing E. coli in animals and animal-derived foods, with some studies indicating genetic similarities between these isolates and those found in human infections. This underscores the urgent need to address antimicrobial resistance as a pressing public health issue. More comprehensive studies are required to understand the evolving landscape of ESBLs and to develop strategic public health policies grounded in the One Health approach, aiming to control and mitigate their prevalence effectively.

Occurrence of Escherichia coli Pathotypes in Diarrheic Calves in a Low-Income Setting

Different E. coli pathotypes are common zoonotic agents. Some of these pathotypes cause recurrent and widespread calf diarrhea and contribute to significant economic losses in the livestock sector worldwide in addition to putting humans at risk. Here, we investigated the occurrence of E. coli pathotypes in diarrheic calves in Ethiopia kept under various calf management practices. One hundred fecal samples were collected from diarrheic calves in 98 different farms. E. coli was isolated in the samples from 99 of the diarrheic calves, and virulence genes were detected in 80% of the samples. The occurrence of E. coli pathotypes in the samples was 32% ETEC, 23% STEC, 18% STEC/ETEC, 3% EPEC, 2% EAEC, and 1% EHEC. No diarrheic calves were positive for the EIEC and DAEC pathotypes. The occurrence of pathotypes was positively associated with female calves (EPEC, p = 0.006), aged less than 2 weeks (STEC, p = 0.059), and calves fed colostrum via the hand method (STEC, p = 0.008 and EAEC, p = 0.003). This study revealed that several E. coli pathotypes occurred among calves affected with diarrhea. Moreover, the presence of a mixed STEC/ETEC pathotypes infection was present in the studied low-income setting. These findings indicate a considerable risk for the zoonotic transmission from calves to humans and the options to provide the better management for younger calves in order to reduce the economic loss.

Evaluation of immunochromatography test for detection of four enteropathogens in the feces of sheep and goats in Kuwait

Background:

Diarrhea in newborn small ruminants continues to be the cause of significant financial loss in sheep and goat farms worldwide. Commercial immunochromatographic (IC) assays have been designed and evaluated to be used for the diagnosis of diarrhea in cattle; however, there are no trials to use rapid tests in small ruminants.

Aim:

This study was carried out in Kuwait to evaluate the performance of the rapid immunochromatography test (BoviD-4, BioNote, Inc, Korea) for diagnostics of Cryptosporidium, rotavirus A (RVA), bovine coronavirus (BCoV), and Escherichia coli K99 (E. coli K99) in fecal samples of sheep and goats.

Methods:

A total of 85 samples were examined using BoviD-4, and the results were compared with that of polymerase chain reaction for Cryptosporidium, RVA, and BCoV, whereas for E. coli K99 it was by isolation and identification as reference tests.

Results:

The kappa test agreement results between the BoviD-4 and reference tests were 0.870 (perfect), 0.783 (substantial), 0.728 (substantial), and 0.281 (fair) for the detection of E. coli K99, Cryptosporidium, RVA, and BCoV, respectively. The sensitivity of BoviD-4 kit was 91.2%, 80.0%, 90.0%, and 37.5% and the specificity was 88.2%, 96.0%, 96.4%, and 92.2% for Cryptosporidium, RVA, E. coli K99, and BCoV, respectively.

Conclusion:

The Bovid-4 kit can be used as a rapid pen-side test for Cryptosporidium spp., E. coli K99, and RVA in the field. Nonetheless, care must be taken while interpreting the BCoV results of the kit.

Characterization of virulence genes in Escherichia coli strains isolated from pre-weaned calves in the Republic of Korea

Background

Escherichia coli is an important cause of diarrhea in calves and its diarrheagenic properties are related to presence of certain virulence genes. In this study, the prevalence of virulence genes F5, F17, F41, sta, stx1, stx2, eae, and saa in E. coli isolated from pre-weaned calves presenting with (n= 329) or without diarrhea (n= 360) was explored using multiplex polymerase chain reaction. We also evaluated the association between detection of E. coli and the presence of diarrhea.

Results

Escherichia coli was detected in 56.3% (388/689) of the fecal samples and showed the highest prevalence (66.5%) in 21–40-day-old calves and the lowest (46.3%) among those that were 1–20 days old. The prevalence of the enterotoxigenic E. coli (ETEC) and Shiga toxin-producing E. coli (STEC) pathotypes was detected in 73.9% and 15.9%, respectively. The results showed no association between diarrhea and the presence of E. coli in general, ETEC or STEC. The F17 gene was the most frequently detected virulence factor in E. coli of calves of all ages regardless of diarrhea. Interestingly, the results show that the calves aged 41–60 days with F17-positive E. coli are at a higher risk for production of Shiga toxin (Stx1; 95% confidence intervals: 1.86–31.95; P = 0.005) compared to calves aged 1–20 days; no association between this finding and diarrhea was observed among the calves of this age group. Moreover, the virulence genes associated with the ETEC and STEC strains were not significantly associated with pathogenicity in this study cohort.

Conclusions

These results suggest that while the incidence of E. coli is age-related, there was no relationship linking E. coli virulence genes to calf age and diarrhea. Furthermore, the present study demonstrated that detection of E. coli strains either with or without virulence factors was not associated with diarrhea in pre-weaned calves.

Analysis of Resistance to Florfenicol and the Related Mechanism of Dissemination in Different Animal-Derived Bacteria

Bacterial resistance to antibiotics has become an important concern for public health. This study was aimed to investigate the characteristics and the distribution of the florfenicol-related resistance genes in bacteria isolated from four farms. A total of 106 florfenicol-resistant Gram-negative bacilli were examined for florfenicol-related resistance genes, and the positive isolates were further characterized. The antimicrobial sensitivity results showed that most of them (100, 94.33%) belonged to multidrug resistance Enterobacteriaceae. About 91.51% of the strains carried floR gene, while 4.72% carried cfr gene. According to the pulsed-field gel electrophoresis results, 34 Escherichia coli were subdivided into 22 profiles, the genetic similarity coefficient of which ranged from 80.3 to 98.0%. The multilocus sequence typing (MLST) results revealed 17 sequence types (STs), with ST10 being the most prevalent. The genome sequencing result showed that the Proteus vulgaris G32 genome consists of a 4.06-Mb chromosome, a 177,911-bp plasmid (pG32-177), and a 51,686-bp plasmid (pG32-51). A floR located in a drug-resistant region on the chromosome of P. vulgaris G32 was with IS91 family transposase, and the other floR gene on the plasmid pG32-177 was with an ISCR2 insertion sequence. The cfr gene was located on the pG32-51 flanked by IS26 element and TnpA26. This study suggested that the mobile genetic elements played an important role in the replication of resistance genes and the horizontal resistance gene transfer.

Causative agents and epidemiology of diarrhea in Korean native calves

Calf diarrhea caused by infectious agents is associated with economic losses in the cattle industry. The purpose of this study was to identify the causative agents and epidemiological characteristics of diarrhea in Korean native calves (KNC). In total, 207 diarrheal KNC aged less than 7 months were investigated. Fecal samples collected from the rectum were examined for causative agents using polymerase chain reaction (PCR) or real-time PCR and the number of oocysts were counted. Fourteen causative agents were detected from 164 of the 207 diarrheal KNC. Rotavirus was the most common agent (34.8%), followed by Eimeria spp. (31.7%), Escherichia coli (22.0%), Giardia spp. (14.0%), Clostridium difficile (9.8%), bovine viral diarrhea virus (8.5%), coronavirus (7.9%), Cryptosporidium spp. (7.3%), torovirus (6.7%), parvovirus (5.5%), norovirus (4.9%), kobuvirus (1.8%), adenovirus (1.2%), and Salmonella spp. (0.6%). About 95 (57.9%) of 164 calves were infected with a single causative agent and 42.1% were infected by multiple agents. No significant difference was observed in mortality between calves infected with a single agent and multiple agents. The occurrence of diarrhea caused by rotavirus, Eimeria spp., kobuvirus, and Giardia spp. was significantly different based on onset age, and the prevalence of diarrhea caused by rotavirus or C. difficile was significantly different between seasons. This study help the understanding of KNC diarrhea for the development of an effective strategy for disease prevention and control, especially in Eastern provinces of South Korea.

Investigation of plasmid-mediated resistance in E. coli isolated from healthy and diarrheic sheep and goats

Escherichia coli is zoonotic bacteria and the emergence of antimicrobial-resistant strains becomes a critical issue in both human and animal health globally. This study was therefore aimed to investigate the plasmid-mediated resistance in E. coli strains isolated from healthy and diarrheic sheep and goats. A total of 234 fecal samples were obtained from 157 sheep (99 healthy and 58 diarrheic) and 77 goats (32 healthy and 45 diarrheic) for the isolation and identification of E. coli. Plasmid DNA was extracted using the alkaline lysis method. Phenotypic antibiotic susceptibility profiles were determined against the three classes of antimicrobials, which resistance is mediated by plasmids (Cephalosporins, Fluoroquinolone, and Aminoglycosides) using the disc-diffusion method. The frequency of plasmid-mediated resistance genes was investigated by PCR. A total of 159 E. coli strains harbored plasmids. The isolates antibiogram showed different patterns of resistance in both healthy and diarrheic animals. A total of (82; 51.5%) E. coli strains were multidrug-resistant. rmtB gene was detected in all Aminoglycoside-resistant E. coli, and the ESBL-producing E. coli possessed different CTX-M genes. Similarly, fluoroquinolone-resistant E. coli possessed different qnr genes. On the analysis of the gyrB gene sequence of fluoroquinolone-resistant E. coli, multiple point mutations were revealed. In conclusion, a high prevalence of E. coli with high resistance patterns to antimicrobials was revealed in the current study, in addition to a wide distribution of their resistance determinants. These findings highlight the importance of sheep and goats as reservoirs for the dissemination of MDR E. coli and resistance gene horizontal transfer.

Molecular characteristics and genotypic diversity of enterohaemorrhagic Escherichia coli O157:H7 isolates in Gauteng region, South Africa

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is one of the major foodborne and waterborne pathogens causing severe diseases and outbreaks worldwide. There is scarcity of EHEC O157:H7 data in South Africa. This study was carried out to determine the molecular characteristics and genotypic diversity of EHEC O157:H7 isolates in the Gauteng region, South Africa. Samples were cultured on selective chromogenic media. Antibiotic susceptibility profile of isolates was determined using the VITEK®-2 automated system. Isolates were characterised using multiplex PCR assays and the genetic diversity was determined using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). A total of 520 samples of which 270 environmental water samples and 250 stool specimens were collected and analysed. Overall, EHEC O157:H7 was recovered from 2.3% (12/520) of samples collected. Environmental water samples and clinical stool specimens showed a prevalence of 4.07% (11/270) and 0.4% (1/250) respectively. Antibiotic susceptibility profile varied from isolates with full susceptibility to isolates with resistance to multiple antibiotics. Most resistance was detected to the penicillins, specifically ampicillin (7/12), amoxicillin (3/12) and piperacillin/Tazobactam (3/12) followed by one of the folate inhibitors, trimethoprim (3/12) and the carbapenems, imipenem and meropenem (2/12) each. Three isolates harboured a combination of Shiga-toxins (Stx)-2, intimin (eae) and enterohaemolysin (hlyA) genes, while two isolates harboured the Stx-1, Stx-2 and hlyA genes. The PFGE performed showed that EHEC O157:H7 isolates were genetically diverse, with two minor pulsotypes and eight singletons. The MLST analysis identified three sequence types (STs) (ST10, ST11 and ST1204) that have been previously reported associated with outbreaks. The STs identified in this study pose a potential public health risk to consumers of untreated environmental water and closed human contacts. There is necessity to enhance surveillance in reducing the propagation of this bacterium which is a public health problem.

Prevalence and antibiotic susceptibility patterns of enteric bacterial pathogens in human and non-human sources in an urban informal settlement in Cape Town, South Africa

Background

In light of rampant childhood diarrhoea, this study investigated bacterial pathogens from human and non-human sources in an urban informal settlement.

Meat from informal abattoirs (n = 85), river water (n = 64), and diarrheic stool (n = 66) were collected between September 2015 and May 2016. A duplex real-time PCR, gel-based PCR, and CHROMagar™STEC were used to screen Tryptic Soy Broth (TSB) for diarrheic E. coli. Standard methods were used to screen for other selected food and waterborne bacterial pathogens.

Results

Pathogens isolated from stool, meat, and surface water included Salmonella enterica (6, 5, 0%), Plesiomonas shigelloides (9, 0, 17%), Aeromonas sobria (3, 3, 0%), Campylobacter jejuni (5, 5, 0%), Shigella flexneri (17, 5, 0%), Vibrio vulnificus (0, 0, 9%), and diarrheic E. coli (21, 3, 7%) respectively. All the isolates were resistant to trimethoprim–sulphamethoxazole.

Conclusions

There was a high burden of drug resistant diarrheal pathogens in the stool, surface water and meat from informal slaughter. Integrated control measures are needed to ensure food safety and to prevent the spread of drug resistant pathogens in similar settings.

A Review of Zoonotic Pathogens of Dromedary Camels

Dromedary, or one-humped, camels Camelus dromedarius are an almost exclusively domesticated species that are common in arid areas as both beasts of burden and production animals for meat and milk. Currently, there are approximately 30 million dromedary camels, with highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability for camels to act as a point source or vector for disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and a growth in the interface with wildlife as camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that the majority of publications (65%) focused on Middle East respiratory syndrome (MERS), brucellosis, Echinococcus granulosus, and Rift Valley fever. The high fatality from MERS outbreaks during 2012-2016 elicited an immediate response from the research community as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Yersinia pestis, Coxiella burnetii, and Crimean-Congo hemorrhagic fever are just as important to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. In this review, we provide an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events.

Comparative genomic analysis of 127 Escherichia coli strains isolated from domestic animals with diarrhea in China

Background

Escherichia coli is an important pathogen that causes diarrhea in both humans and animals. To determine the relationships between putative virulence factors and pathotypes or host taxa, many molecular studies on diarrhea-associated E. coli have been reported. However, little is known regarding genome-wide variation of E. coli from animal hosts. In this study, we performed whole genome sequencing of 127 E. coli isolates from sheep and swine with diarrhea in China. We compared isolates to explore the phylogenomic relatedness based on host origin. We explored the relationships of putative virulence factors across host taxa and pathotypes. Antimicrobial resistance was also tested.

Results

The E. coli genomes in this study were diverse with clear differences in the SNP, MLST, and O serotypes. Seven putative virulence factors (VFs) were prevalent (> 95%) across the isolates, including Hcp, csgC, dsdA, feoB, fepA, guaA, and malX. Sixteen putative VFs showed significantly different distributions (P < 0.05) in strains from sheep and swine and were primarily adhesion- and toxin-related genes. Some putative VFs were co-occurrent in some specific pathotypes and O serotypes. The distribution of 4525 accessory genes of the 127 strains significantly differed (P < 0.05) between isolates obtained from the two animal species. The 127 animal isolates sequenced in this study were each classified into one of five pathotypes: EAEC, ETEC, STEC, DAEC, and EPEC, with 66.9% of isolates belonging to EAEC. Analysis of stx subtypes and a minimum spanning tree based on MLST revealed that STEC isolates from sheep and EAEC isolates from sheep and swine have low potential to infect humans. Antibiotic resistance analysis showed that the E. coli isolates were highly resistant to ampicillin and doxycycline. Isolates from southeast China were more resistant to antibiotics than isolates from northwest China. Additionally, the plasmid-mediated colist in resistance gene mcr-1 was detected in 15 isolates, including 4 from sheep in Qinghai and 11 from swine in Jiangsu.

Conclusions

Our study provides insight into the genomes of E. coli isolated from animal sources. Distinguishable differences between swine and sheep isolates at the genomic level provides a baseline for future investigations of animal E. coli pathogens.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5588-2) contains supplementary material, which is available to authorized users.

Porcine commensal Escherichia coli: a reservoir for class 1 integrons associated with IS26

Porcine faecal waste is a serious environmental pollutant. Carriage of antimicrobial-resistance genes (ARGs) and virulence-associated genes (VAGs), and the zoonotic potential of commensal Escherichia coli from swine are largely unknown. Furthermore, little is known about the role of commensal E. coli as contributors to the mobilization of ARGs between food animals and the environment. Here, we report whole-genome sequence analysis of 103 class 1 integron-positive E. coli from the faeces of healthy pigs from two commercial production facilities in New South Wales, Australia. Most strains belonged to phylogroups A and B1, and carried VAGs linked with extraintestinal infection in humans. The 103 strains belonged to 37 multilocus sequence types and clonal complex 10 featured prominently. Seventeen ARGs were detected and 97 % (100/103) of strains carried three or more ARGs. Heavy-metal-resistance genes merA, cusA and terA were also common. IS26 was observed in 98 % (101/103) of strains and was often physically associated with structurally diverse class 1 integrons that carried unique genetic features, which may be tracked. This study provides, to our knowledge, the first detailed genomic analysis and point of reference for commensal E. coli of porcine origin in Australia, facilitating tracking of specific lineages and the mobile resistance genes they carry.

Molecular Characterization and Antimicrobial Resistance Pattern of Escherichia coli Recovered from Wastewater Treatment Plants in Eastern Cape South Africa

Wastewater treatment plants (WWTPs) are designed to eliminate organic matter and pathogens but most WWTPs discharges antimicrobial resistance pathogens into aquatic milieu. The study aimed to examine the antibiotics resistant patterns and the presence of some resistance genes among E. coli isolates from WWTPs effluents. Water were collected from WWTPs final effluents, filtered through nitrocellulose membrane and the filter papers were placed on chromogenic agar plates, incubated for 24 h at 37 °C. Presumptive E. coli isolates (173) were obtained from the culture method. From the presumptive E. coli isolates screened by polymerase chain reaction (PCR), 111 isolates were positive and the positive isolates were further screened for six diarrheagenic E. coli pathotypes (EPEC, ETEC, EHEC, DAEC, EIEC, and EAEC) and from the pathotypes screened, nine isolates harboured daaE gene. The phenotypic susceptibility patterns of the 111 isolates to 12 antibiotics were determined by Kirby-Bauer disk diffusion technique. All the isolates were resistant to erythromycin and clindamycin. From the resistance genes screened, 31 isolates harboured mcr-1 gene and nine isolates harboured ermA gene. The study reveals that water samples recovered from the final effluents of WWTPs may likely be one of the major sources of antibiotic-resistant in Escherichia coli.

Genetic diversity and antibiogram profile of diarrhoeagenic Escherichia coli pathotypes isolated from human, animal, foods and associated environmental sources

INTRODUCTION

Infectious diarrhoea particularly due to pathogenic bacteria is a major health problem in developing countries, including India. Despite significant reports of diarrhoeagenic Escherichia coli (DEC) pathotypes around the globe, studies which address genetic relatedness, antibiogram profile and their correlation with respect to their isolation from different sources are sparse. The present study determines isolation and identification of DEC pathotypes from different sources, their genetic characterisation, antibiogram profile and their correlation if any.

MATERIALS AND METHODS

A total of 336 samples comprising diarrhoeic stool samples from infants (n=103), young animal (n=106), foods (n=68) and associated environmental sources (n=59) were collected from Bareilly region of India. All the samples were screened by using standard microbiological methods for the detection of E. coli. The identified E. coli were then confirmed as DEC pathotypes using polymerase chain reaction-based assays. Those DEC pathotypes identified as Enteroaggregative E. coli (EAEC) were further confirmed using HEp-2 adherence assay. All the isolated DEC pathotypes were studied for their genetic diversity using pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing was performed by using disc diffusion method as per Clinical Laboratory Standards Institute guidelines.

RESULTS AND DISCUSSION

Of the four DEC pathotypes investigated, EAEC was found to be the predominant pathogen with an isolation rate of 16.5% from infants, 17.9% from young animals, 16.2% from foods and 3.4% from the associated environmental sources. These EAEC isolates, on further characterisation, revealed predominance of 'atypical' EAEC, with an isolation rate of 10.7% from infants, 15.1% from young animals, 16.2% from foods, and 3.4% from the associated environmental sources. On PFGE analysis, discrimination was evident within DEC pathotypes as 52 unique pulsotypes were observed for 59 recovered DEC pathotypes. However, a few EAEC isolates were found to be clonal (clusters A, B, C, D, F, G, and H) irrespective of their source of isolation, suggests sharing and/or circulation among different sources. Further, a high antibiotic resistance pattern was observed among isolated DEC pathotypes as almost 86.4% of isolates were found to be resistant against ≥3 tested drugs.

Investigation of enteropathogenic Escherichia coli and Shiga toxin-producingEscherichia coli associated with hemolytic uremic syndrome in İzmir Province, Turkey

BACKGROUND/AIM

The purpose of this study was to investigate Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic Escherichia coli (EPEC) strains originating from diarrheagenic patients.

MATERIALS AND METHODS

A total of 102 patients with diarrhea between October 2012 and January 2013 were enrolled in this study. Multiplex and standard polymerase chain reactions were performed to detect and distinguish STEC and EPEC strains. O serotyping of EPEC was carried out by monovalent antisera. The O and H serotyping of STEC strains was performed at the Refik Saydam Institute, Ankara.

RESULTS

A total of 5 (3.42%) strains were identified as STEC, and 3 strains (2.05%) were atypical EPEC. One of the STEC serotypes was O157:H7 carrying VT1, Stx1A, and escv genes. The other STEC strain was identified as O174:H21, which is associated with hemolytic uremic syndrome and consists of VT2 and Stx2A genes. One of the EPEC and three of the STEC serotypes were nontypeable. The serotypes of the atypical EPEC strains were identified as O114 and O26.

CONCLUSION

To the best of our knowledge, this is the first report of O174:H21 from the İzmir region that was shown to be a Shiga toxin-producing non-O157 serotype of STEC.

Persistent spread of the rmtB 16S rRNA methyltransferase gene among Escherichia coli isolates from diseased food-producing animals in China

A total of 963 non-duplicate Escherichia coli strains isolated from food-producing animals between 2002 and 2012 were screened for the presence of the 16S rRNA methyltransferase genes. Among the positive isolates, resistance determinants to extended spectrum β-lactamases, plasmid-mediated quinolone resistance genes as well as floR and fosA/A3/C2 were detected using PCR analysis. These isolates were further subjected to antimicrobial susceptibility testing, molecular typing, PCR-based plasmid replicon typing and plasmid analysis. Of the 963 E. coli isolates, 173 (18.0%), 3 (0.3%) and 2 (0.2%) were rmtB-, armA- and rmtE-positive strains, respectively. All the 16S rRNA methyltransferase gene-positive isolates were multidrug resistant and over 90% of them carried one or more type of resistance gene. IncF (especially IncFII) and non-typeable plasmids played the main role in the dissemination of rmtB, followed by the IncN plasmids. Plasmids that harbored rmtB ranged in size from 20kb to 340kb EcoRI-RFLP testing of the 109 rmtB-positive plasmids from different years and different origins suggested that horizontal (among diverse animals) and vertical transfer of IncF, non-typeable and IncN-type plasmids were responsible for the spread of rmtB gene. In summary, our findings highlight that rmtB was the most prevalent 16S rRNA methyltransferase gene, which present persistent spread in food-producing animals in China and a diverse group of plasmids was responsible for rmtB dissemination.

Characterization of CTX-M-14-producing Escherichia coli from food-producing animals

Bacterial resistance to the third-generation cephalosporin antibiotics has become a major concern for public health. This study was aimed to determine the characteristics and distribution of bla CTX-M-14, which encodes an extended-spectrum β-lactamase, in Escherichia coli isolated from Guangdong Province, China. A total of 979 E. coli isolates isolated from healthy or diseased food-producing animals including swine and avian were examined for bla CTX-M-14 and then the bla CTX-M-14 -positive isolates were detected by other resistance determinants [extended-spectrum β-lactamase genes, plasmid-mediated quinolone resistance, rmtB, and floR] and analyzed by phylogenetic grouping analysis, PCR-based plasmid replicon typing, multilocus sequence typing, and plasmid analysis. The genetic environments of bla CTX-M-14 were also determined by PCR. The results showed that fourteen CTX-M-14-producing E. coli were identified, belonging to groups A (7/14), B1 (4/14), and D (3/14). The most predominant resistance gene was bla TEM (n = 8), followed by floR (n = 7), oqxA (n = 3), aac(6')-1b-cr (n = 2), and rmtB (n = 1). Plasmids carrying bla CTX-M-14 were classified to IncK, IncHI2, IncHI1, IncN, IncFIB, IncF or IncI1, ranged from about 30 to 200 kb, and with insertion sequence of ISEcp1, IS26, or ORF513 located upstream and IS903 downstream of bla CTX-M-14. The result of multilocus sequence typing showed that 14 isolates had 11 STs, and the 11 STs belonged to five groups. Many of the identified sequence types are reported to be common in E. coli isolates associated with extraintestinal infections in humans, suggesting possible transmission of bla CTX-M-14 between animals and humans. The difference in the flanking sequences of bla CTX-M-14 between the 2009 isolates and the early ones suggests that the resistance gene context continues to evolve in E. coli of food producing animals.

Molecular analysis and antimicrobial susceptibility of enterotoxigenic Escherichia coli from diarrheal patients

A total of 123 enterotoxigenic Escherichia coli (ETEC) isolates from diarrheal patients from June to December 2012 in Shanghai, China, were examined to determine their genetic relatedness using multilocus sequence typing and pulsed-field gel electrophoresis (PFGE) and for the presence of virulence genes and antimicrobial susceptibility. Twenty-nine sequence types (STs) and 63 PFGE patterns were identified, and results from the 2 subtyping methods correlated well. The 12 isolates of PFGE cluster B all belonged to ST-2332 and were associated with nosocomial neonatal diarrhea. Isolates of a cluster usually had the same set of virulence factors, whereas isolates of different PFGE clusters carried diverse combinations of virulence determinants. Isolates belonging to ST-2332 and ST-182 (n=9) were resistant to at least 6 antimicrobials. Our findings highlighted the need of active surveillance programs for infectious diseases collecting data at both epidemiological and genetic levels that can detect high-risk lineages of pathogens in order to rapidly identify disease outbreaks.