Characterization of extended-spectrum beta-lactamases produced by Escherichia coli isolated from hospitalized and nonhospitalized patients: emergence of CTX-M-15-producing strains causing urinary tract infections

Prevalence and Diversity of Antibiotic Resistant Escherichia coli From Anthropogenic-Impacted Larut River

Aquatic environments, under frequent anthropogenic pressure, could serve as reservoirs that provide an ideal condition for the acquisition and dissemination of antibiotic resistance genetic determinants. We investigated the prevalence and diversity of antibiotic-resistant Escherichia coli by focusing on their genetic diversity, virulence, and resistance genes in anthropogenic-impacted Larut River. The abundance of E. coli ranged from (estimated count) Est 1 to 4.7 × 105 (colony-forming units per 100 ml) CFU 100 ml−1 to Est 1 to 4.1 × 105 CFU 100 ml−1 with phylogenetic group B1 (46.72%), and A (34.39%) being the most predominant. The prevalence of multiple antibiotic resistance phenotypes of E. coli, with the presence of tet and sul resistance genes, was higher in wastewater effluents than in the river waters. These findings suggested that E. coli could be an important carrier of the resistance genes in freshwater river environments. The phylogenetic composition of E. coli and resistance genes was associated with physicochemical properties and antibiotic residues. These findings indicated that the anthropogenic inputs exerted an effect on the E. coli phylogroup composition, diversification of multiple antibiotic resistance phenotypes, and the distribution of resistance genes in the Larut River.

Quantitative Risk Assessment for the Introduction of Carbapenem-Resistant Enterobacteriaceae (CPE) into Dutch Livestock Farms

Early detection of emerging carbapenem-resistant Enterobacteriaceae (CPE) in food-producing animals is essential to control the spread of CPE. We assessed the risk of CPE introduction from imported livestock, livestock feed, companion animals, hospital patients, and returning travelers into livestock farms in The Netherlands, including (1) broiler, (2) broiler breeder, (3) fattening pig, (4) breeding pig, (5) farrow-to-finish pig, and (6) veal calf farms. The expected annual number of introductions was calculated from the number of farms exposed to each CPE source and the probability that at least one animal in an exposed farm is colonized. The total number of farms with CPE colonization was estimated to be the highest for fattening pig farms, whereas the probability of introduction for an individual farm was the highest for broiler farms. Livestock feed and imported livestock are the most likely sources of CPE introduction into Dutch livestock farms. Sensitivity analysis indicated that the number of fattening pig farms determined the number of high introductions in fattening pigs from feed, and that uncertainty on CPE prevalence impacted the absolute risk estimate for all farm types. The results of this study can be used to inform risk-based surveillance for CPE in livestock farms.

Antimicrobial Resistance Profiling and Molecular Epidemiological Analysis of Extended Spectrum β-Lactamases Produced by Extraintestinal Invasive Escherichia coli Isolates From Ethiopia: The Presence of International High-Risk Clones ST131 and ST410 Revealed

The treatment of invasive Escherichia coli infections is a challenge because of the emergence and rapid spread of multidrug resistant strains. Particular problems are those strains that produce extended spectrum β-lactamases (ESBL’s). Although the global characterization of these enzymes is advanced, knowledge of their molecular basis among clinical E. coli isolates in Ethiopia is extremely limited. This study intends to address this knowledge gap. The study combines antimicrobial resistance profiling and molecular epidemiology of ESBL genes among 204 E. coli clinical isolates collected from patient urine, blood, and pus at four geographically distinct health facilities in Ethiopia. All isolates exhibited multidrug resistance, with extensive resistance to ampicillin and first to fourth line generation cephalosporins and sulfamethoxazole-trimethoprim and ciprofloxacin. Extended spectrum β-lactamase genes were detected in 189 strains, and all but one were positive for CTX-Ms β-lactamases. Genes encoding for the group-1 CTX-Ms enzymes were most prolific, and CTX-M-15 was the most common ESBL identified. Group-9 CTX-Ms including CTX-M-14 and CTX-27 were detected only in 12 isolates and SHV ESBL types were identified in just 8 isolates. Bacterial typing revealed a high amount of strains associated with the B2 phylogenetic group. Crucially, the international high risk clones ST131 and ST410 were among the sequence types identified. This first time study revealed a high prevalence of CTX-M type ESBL’s circulating among E. coli clinical isolates in Ethiopia. Critically, they are associated with multidrug resistance phenotypes and high-risk clones first characterized in other parts of the world.

Genetic but No Phenotypic Associations between Biocide Tolerance and Antibiotic Resistance in Escherichia coli from German Broiler Fattening Farms

Biocides are frequently applied as disinfectants in animal husbandry to prevent the transmission of drug-resistant bacteria and to control zoonotic diseases. Concerns have been raised, that their use may contribute to the selection and persistence of antimicrobial-resistant bacteria. Especially, extended-spectrum β-lactamase- and AmpC β-lactamase-producing Escherichia coli have become a global health threat. In our study, 29 ESBL-/AmpC-producing and 64 NON-ESBL-/AmpC-producing E.coli isolates from three German broiler fattening farms collected in 2016 following regular cleaning and disinfection were phylogenetically characterized by whole genome sequencing, analyzed for phylogenetic distribution of virulence-associated genes, and screened for determinants of and associations between biocide tolerance and antibiotic resistance. Of the 30 known and two unknown sequence types detected, ST117 and ST297 were the most common genotypes. These STs are recognized worldwide as pandemic lineages causing disease in humans and poultry. Virulence determinants associated with extraintestinal pathogenic E.coli showed variable phylogenetic distribution patterns. Isolates with reduced biocide susceptibility were rarely found on the tested farms. Nine isolates displayed elevated MICs and/or MBCs of formaldehyde, chlorocresol, peroxyacetic acid, or benzalkonium chloride. Antibiotic resistance to ampicillin, trimethoprim, and sulfamethoxazole was most prevalent. The majority of ESBL-/AmpC-producing isolates carried bla_CTX-M (55%) or bla_CMY-2 (24%) genes. Phenotypic biocide tolerance and antibiotic resistance were not interlinked. However, biocide and metal resistance determinants were found on mobile genetic elements together with antibiotic resistance genes raising concerns that biocides used in the food industry may lead to selection pressure for strains carrying acquired resistance determinants to different antimicrobials.

Fecal Carriage and Genetic Characterization of CTX-M-1/9/1-Producing Escherichia coli From Healthy Humans in Hangzhou, China

CTX-M-199, a novel chimeric β-lactamase which mediated resistance to sulbactam and tazobactam, was recently identified in Hangzhou, China. This study investigated the prevalence of fecal carriage of bacteria producing CTX-M-199 and other CTX-M-1/9/1-type enzymes among healthy individuals and characterized the genetic features of bla_{CTX–M–1/9/1}-bearing mobile elements. A total of 74 Enterobacterales strains carrying various bla_{CTX–M–1/9/1} genes, including bla_CTX–M–64 (n = 40, carriage rate of 0.74%), bla_{CTX–M–199} (n = 23, 0.40%), bla_{CTX–M–123} (n = 5, 0.10%), novel bla_{CTX–M–153} (n = 5, 0.10%), and bla_{CTX–M–132} (n = 2, 0.04%), were isolated from 68 out of 5,000 (1.36%) fecal samples of healthy adults in Hangzhou City. Phylogenetic analysis based on whole-genome sequencing data showed that 72 bla_{CTX–M–1/9/1}-bearing Escherichia coli isolates were clustered into four major clades, three of which included CTX-M-199 producers. Sixty out of 75 bla_{CTX–M–1/9/1} genes were located on plasmids belonging to four Inc types: IncI2, IncI1, IncFIB, and IncHI2. The bla_{CTX–M–199} genes were harbored by three of the four types of plasmids except for IncHI2. All these bla_{CTX–M–1/9/1} genes were carried on an ISEcp1-mediated transposition unit. In conclusion, human fecal carriage of bla_{CTX–M–1/9/1} was low in healthy populations of China. The ISEcp1 was commonly associated with bla_{CTX–M–1/9/1} and may mediate its transmission on various mobile elements. Our findings provide insights into the dissemination and the development of further measures for the control of pathogens producing CTX-M-1/9/1-type enzymes.

Extended Spectrum Beta Lactamase (ESBL), blaTEM,blaSHV and blaCTX-M, Resistance Genes in Community and Healthcare Associated Gram Negative Bacteria from Osun State, Nigeria

BACKGROUND

Extended Spectrum Beta Lactamase (ESBL) production in gram negative bacteria confers multiple antibiotic resistance, adversely affecting antimicrobial therapy in infected individuals. ESBLs result from mutations in β-lactamases encoded mainly by the bla_TEM,bla_SHV and bla_CTX-M genes. The prevalence of ESBL producing bacteria has been on the increase globally, especially its upsurge among isolates from community-acquired infections has been observed.

AIM

To determine ESBL prevalence and identify ESBL genes among clinical isolates in Osun State, Nigeria.

MATERIAL AND METHODS

A cross-sectional study was carried out from August 2016 - July 2017 in Osun State, Nigeria. Three hundred and sixty Gram-negative bacteria recovered from clinical samples obtained from both community and healthcare-associated infections were tested. They included 147 Escherichia coli (40.8%), 116 Klebsiella spp (32.2%), 44 Pseudomonas aeruginosa (12.2%) and 23 Proteus vulgaris (6.4%) isolates. Others were Acinetobacter baumannii, Serratia rubidae, Citrobacter spp, Enterobacter spp and Salmonella typhi. Disk diffusion antibiotic susceptibility testing was carried out, isolates were screened for ESBL production and confirmed using standard laboratory procedures. ESBLs resistance genes were identified by Polymerase Chain Reaction (PCR).

RESULTS

All isolates demonstrated multiple antibiotic resistance. Resistance to ampicillin, amoxicillin with clavulanate and erythromycin was 100%, whereas resistance to Imipenem was very low (5.0%). The overall prevalence of ESBL producers was 41.4% with Klebsiella spp as the highest ESBL producing Enterobacteriacaea. ESBL producers were more prevalent among the hospital pathogens than community pathogens, 58% vs. 29.5% (p=0.003). ESBL genes were detected in all ESBL producers with the bla_CTX-M gene predominating (47.0%) followed by bla_TEM (30.9%) and bla_SHV gene was the least, 22.1%. The bla_CTX-M gene was also the most prevalent in the healthcare pathogens (62%) but it accounted for only 25% in those of community origin.

CONCLUSION

A high prevalence of ESBL producing gram-negative organisms occurs both in healthcare and in the community in our environment with the CTX-M variant predominating. Efforts to control the spread of these pathogens should be addressed.

Trends in antimicrobial resistance over 10 years among key bacterial pathogens from Canadian hospitals: results of the CANWARD study 2007-16

OBJECTIVES

We sought to analyse 10 years of longitudinal surveillance data (2007-16) from the CANWARD study and describe emerging trends in antimicrobial resistance for key bacterial pathogens across Canada.

METHODS

Longitudinal data from CANWARD study sites that contributed isolates every year from 2007 to 2016 were analysed to identify trends in antimicrobial resistance over time using univariate tests of trend and multivariate regression models to account for the effects of patient demographics.

RESULTS

Statistically significant increases occurred in the proportion of Escherichia coli isolates resistant to extended-spectrum cephalosporins, amoxicillin/clavulanate, trimethoprim/sulfamethoxazole and ciprofloxacin. Similarly, the proportion of Klebsiella pneumoniae isolates resistant to extended-spectrum cephalosporins, amoxicillin/clavulanate, trimethoprim/sulfamethoxazole, ciprofloxacin and carbapenems increased during the study. The proportion of Enterobacter cloacae isolates resistant to ceftazidime and trimethoprim/sulfamethoxazole increased. The proportion of both ESBL-positive E. coli and K. pneumoniae (including bloodstream isolates) increased significantly between 2007 and 2016. A reduction in the proportion of Pseudomonas aeruginosa that were ciprofloxacin, cefepime, colistin, amikacin and gentamicin resistant and an increase in the proportion of P. aeruginosa isolates non-susceptible to meropenem were observed. The proportion of isolates of Staphylococcus aureus non-susceptible to clarithromycin, clindamycin and trimethoprim/sulfamethoxazole decreased over time while an increase in the proportion of isolates of Streptococcus pneumoniae non-susceptible to clarithromycin, clindamycin and doxycycline was observed.

CONCLUSIONS

Increases in Enterobacteriaceae resistance to multiple classes of antimicrobials, increases in ESBL-positive E. coli and K. pneumoniae, and the small but significant increase in carbapenem-resistant K. pneumoniae were the most remarkable changes in antimicrobial resistance observed from 2007 to 2016 in Canada.

Antimicrobial resistant and extended-spectrum ß-lactamase (ESBL) producing Escherichia coli isolated from fecal samples of African dromedary camels

This study was conducted to determine the distribution of antimicrobial resistance among Escherichia coli isolated from feces of healthy dromedary camels in Kenya. A total of 162 fecal samples were cultivated for E. coli. Samples were also subcultivated to detect E. coli with extended-spectrum ß-lactamases (ESBLs). Antimicrobial susceptibility testing (AST) was performed by disk diffusion using a panel of 16 antimicrobials. In addition, isolates were screened for the presence of the plasmid-mediated colistin resistance genes mcr-1 to mcr-5.

Samples from 20 (12.4%) of the camels contained antimicrobial resistant (AMR) E. coli, and 85% of the AMR isolates were multidrug resistant (MDR). The highest frequency of resistance was observed to tetracycline (11.7%), followed by ampicillin and streptomycin (both 10.5%), and sulfamethoxazole/trimethoprim (9.9%). Two (1.2%) of the isolates showed intermediate resistance to cefazolin and streptomycin, respectively. All the isolates were susceptible to amoxycillin/clavulanic acid, ciprofloxacin, fosfomycin, aztreonam and kanamycin, and 86.4% of the isolates were susceptible to all 16 antimicrobials used in this study. The prevalence of fecal carriage of ESBL producing E. coli was 0.6%. PCR and amplicon sequencing showed that the ESBL producer belonged to E. coli phylogenetic group A, sequence type (ST) 48, and harbored bla_CTX-M-15. None of the isolates contained mcr genes. The results indicate that dromedary camels in Kenya may be reservoirs of AMR E. coli, including ESBL producers, that could potentially be transmitted to humans by direct contact or via the food chain.

Extended-spectrum beta-lactamases and plasmid diversity in urinary isolates of Escherichia coli in Croatia: a nation-wide, multicentric, retrospective study

In recent years, a dramatic increase in the prevalence of Escherichia coli strains producing extended-spectrum β-lactamases (ESBLs) has been observed - both in the community and in healthcare settings. This multicentric study aimed to characterize ESBLs produced by E. coli isolates causing hospital-onset and community urinary tract infections, as well as to compare their antimicrobial sensitivity patterns, β-lactamase content and plasmid types. Phenotypic tests for the detection of ESBLs and plasmid-mediated AmpC β-lactamases were initially pursued, followed by molecular detection of resistance genes, plasmid characterization, genotyping with pulsed-field gel electrophoresis and whole genome sequencing (WGS). The isolates exhibited high level of resistance to expanded-spectrum cephalosporins (ESC) and carried CTX-M (cefotaximase-Munich) or TEM (Temoniera) β-lactamases. All six representative isolates subjected to WGS belonged to the widespread clone ST131. In conclusion, our study demonstrated dissemination of group 1 CTX-M positive E. coli in different geographic regions of Croatia, but also different components of the health care systems (hospitals, nursing homes and the community) and confirmed the switch from SHV-2 (suphydril variant) and SHV-5 ESBLs to the nation-wide predominance of group 1 CTX-M β-lactamases. Different plasmids were shown to be associated with the dissemination of bla_CTX-M genes in different geographic regions of Croatia.

Characterization of O25b-ST131 Escherichia coli Clone Producing CTX-M-15, DHA-4, and CMY-42 in Urinary Tract Infections in a Tunisian Island

The dissemination of extended-spectrum β-lactamases encoding genes in Escherichia coli, especially in the uropathogenic O25b-ST131 E. coli clone, constitutes a real concern. We aimed to identify the molecular mechanisms of resistance to cephalosporins among E. coli clinical isolates and to estimate the prevalence of the uropathogenic O25b-ST131 clone in our study. Forty-two cephalosporin-resistant E. coli implicated in urinary tract infections were collected from the Regional Hospital of a southeastern Tunisian Island from April 2015 to August 2016. Molecular screening of β-lactamases encoding genes by PCR and sequencing showed that the majority of our isolates harbored bla_CTX-M gene (bla_CTX-M-15 [n = 36], bla_CTX-M-14 [n = 2]). Nevertheless, the bla_SHV, bla_TEM, and bla_OXA-1 genes were not detected. Various class C β-lactamases encoding genes were observed in association or not with bla_CTX-M genes and were as follows: bla_ampC (n = 14), bla_CMY-42 (n = 7), bla_CMY-2 (n = 1), and bla_DHA-4 (n = 1). The research of O25b-ST131 clone was carried out by duplex PCR (pabB and trpA genes) and revealed that most of our isolates (n = 30) belonged to this clone. We also noted that the majority of our isolates belonged to the B2 phylogenetic group (n = 32), five isolates to the B1 phylogenetic group, three isolates to the D phylogenetic group, and only two isolates belonged to the A phylogenetic group. Our study provides new epidemiological information about E. coli clinical isolates in this area. Indeed, this is the first report of CTX-M-14 producing O25b-ST131 E. coli in our country and the first report of DHA-4 and CMY-42 producing E. coli in Tunisia.

Genomic Epidemiology of Major Extraintestinal Pathogenic Escherichia coli Lineages Causing Urinary Tract Infections in Young Women Across Canada

BACKGROUND

A few extraintestinal pathogenic Escherichia coli (ExPEC) multilocus sequence types (STs) cause the majority of community-acquired urinary tract infections (UTIs). We examine the genomic epidemiology of major ExPEC lineages, specifically factors associated with intestinal acquisition.

METHODS

A total of 385 women with UTI caused by E. coli across Canada were asked about their diet, travel, and other exposures. Genome sequencing was used to determine both ST and genomic similarity. Logistic regression was used to identify factors associated with the acquisition of and infection with major ExPEC STs relative to minor ExPEC STs.

RESULTS

ST131, ST69, ST73, ST127, and ST95 were responsible for 54% of all UTIs. Seven UTI clusters were identified, but genomes from the ST95, ST127, and ST420 clusters exhibited as few as 3 single nucleotide variations across the entire genome, suggesting recent acquisition. Furthermore, we identified a cluster of UTIs caused by 6 genetically-related ST1193 isolates carrying mutations in gyrA and parC. The acquisition of and infection with ST69, ST95, ST127, and ST131 were all associated with increased travel. The consumption of high-risk foods such as raw meat or vegetables, undercooked eggs, and seafood was associated with acquisition of and infection with ST69, ST127, and ST131, respectively.

CONCLUSIONS

Reservoirs may aid in the dissemination of pandemic ExPEC lineages in the community. Identifying ExPEC reservoirs may help prevent future emergence and dissemination of high-risk lineages within the community setting.

Multilocus sequence typing and bla ESBL characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolated from healthy humans and swine in Northern Thailand

Purpose

Here, we investigated the genetic relationships and characteristics of extended- spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli) isolates from healthy hosts, humans in the community and swine among the livestock of Amphor Mueang, Lamphun Province, Thailand.

Patients and methods

Four hundred and nine rectal swabs were collected from healthy people and swine. A total of 212 ESBL-E. coli was isolated and phenotypically confirmed by a combination disk method. Putative ESBL-encoding genes, including bla_CTX-M, bla_TEM, and bla_SHV, were examined by multiplex-PCR. Randomly selected 42 ESBL-E. coli isolates were whole genome sequenced to characterize the ESBL-encoding genes and identify additional antimicrobial resistance genes. The genetic relatedness of 212 ESBL-E. coli was investigated by multilocus sequence typing.

Results

Overall, bla_CTX-M was the dominant ESBL-encoding gene found in 95.75% of the isolates, followed by bla_TEM (60.85%) and bla_SHV (2.40%). While bla_CTX-M-55 was the most common bla_ESBL subgroup found in this study. Whole genome sequencing showed a total of 15 different antimicrobial resistance genes other than bla_ESBL, including sul, qnr, aph(3ʹ)-Ia, among the selected 42 ESBL-E. coli isolates. Over half of the ESBL-E. coli (56.60%) carried bla_CTX-M co-existing with bla_TEM. The most common sequence types (STs) identified from human isolates were ST131, ST101, and ST70 while those isolated from swine were ST10, ST48, and ST131. ST131 strains carrying bla_CTX-M were the major isolated ESBL-E. coli strains, supporting a previous study that considered this strain truly pathogenic. Noticeably, 66.51% of ESBL-E. coli strains shared 19 identical STs, including a host-restricted ST131 between humans and swine, suggesting that transmission between these two hosts might be possible.

Conclusion

Proof of a direct transfer of ESBL-E. coli from animals to humans, or vice versa, is required for further elucidation. The ESBL-E. coli isolated from both types of healthy hosts may serve as a reservoir for community-acquired antimicrobial resistance.

Phenotypic and genotypic characterization of multi-drug-resistant Escherichia coli isolates harboring blaCTX-M group extended-spectrum β-lactamases recovered from pediatric patients in Shenzhen, southern China

Aims and Objectives: The emergence and spread of extended-spectrum β-lactamases (ESBLs) particularly CTX-M producing multi-drug-resistant (MDR) Escherichia coli (E. coli) is one of the greatest challenges for community health globally. The study investigated the phenotypic and genotypic characteristics of ESBLs-producing E. coli recovered from pediatric patients from Shenzhen Children’s Hospital, China.

Materials and methods: Present study, a total of 2,670 isolates of E. coli were collected from Shenzhen Children’s Hospital, China of which 950 were ESBLs producer. ESBLs production was confirmed by using the combination disc diffusion method, and antimicrobial susceptibility test was detected. In addition, β-lactamase-producing genes and co-existence of carbapenem/colistin resistance genes were determined by PCR assay and sequencing. The diversity and phylogenetic relationship were determined by multi-locus sequence typing method.

Results: Thirty-five percent (n=950) prevalence of ESBLs-producing E. coli we reported in Shenzhen, China of which 50 ESBLs producing E. coli were randomly selected for a further characterization. All 50 ESBLs- producing E. coli isolates revealed MDR phenotype and 100% were resistant to Ampicillin/sulbactam, Ampicillin, Cefazolin, and Ceftriaxone. All 50 ESBLs producers harbored at least one type of β-lactamase gene particular bla_CTX-M. The PCR and sequencing revealed the most common CTX-M subtype was bla_CTX-M-15 (n=18), followed by bla_CTX-M-14 (n=16), bla_CTX-M-90 (n=9), bla_CTX-M-55 (n=3), bla_CTX-M-27, bla_CTX-M-101, and bla_CTX-M-211 each (n=1). Co-existence of bla_CTX-M with bla_TEM, bla_SHV, bla_GES, and bla_VEB was detected in few isolates. Among identified sequence types, ST131 (12%) was more dominant in ESBLs-producing E. coli. Phylogenetic group A was the most prominent group among the ESBLs-producing E. coli based on multiplex PCR.

Conclusion: Our study shows the prevalence of bla_CTX-M gene in ESBLs-producing E. coli in pediatric patients in Shenzhen, China. We highlight the importance to monitor the emergence and trends of ESBLs-producing isolates in a pediatric healthcare setting.

Distribution of ExPEC Virulence Factors, bla CTX-M, fosA3, and mcr-1 in Escherichia coli Isolated From Commercialized Chicken Carcasses

Pathogenic Escherichia coli found in humans and poultry carcasses harbor similar virulence and resistance genes. The present study aimed to analyze the distribution of extraintestinal pathogenic E. coli (ExPEC) virulence factors (VF), bla_CTX−M groups, fosA3, and mcr-1 genes in E. coli isolated from commercialized chicken carcasses in southern Brazil and to evaluate their pathogenic risk. A total of 409 E. coli strains were isolated and characterized for genes encoding virulence factors described in ExPEC. Results of antimicrobial susceptibility testing confirmed that the strains were resistant to β-lactams, fosfomycin, colistin, and others resistance groups. The highest prevalence of VFs was observed in isolates belonging to the CTX-M groups, especially the CTX-M-2 group, when compared to those in other susceptible strains or strains with different mechanisms of resistance. Furthermore, ESBL strains were found to be 1.40 times more likely to contain three to five ExPEC virulence genes than non-ESBL strains. Our findings revealed the successful conjugation between ESBL-producing E. coli isolated from chicken carcass and the E. coli recipient strain J53, which suggested that genetic determinants encoding CTX-M enzymes may have originated from animals and could be transmitted to humans via food chain. In summary, chicken meat is a potential reservoir of MDR E. coli strains harboring resistance and virulence genes that could pose serious risks to human public health.

International high-risk clones of Klebsiella pneumoniae KPC-2/CC258 and Escherichia coli CTX-M-15/CC10 in urban lake waters

The emergence of high-risk clones of multidrug-resistant (MDR) bacteria in aquatic environments has generated an important public health problem, creating an urgent need to strengthen surveillance. This study reports the occurrence of clinically significant MDR Enterobacteriaceae and non-fermentative bacteria carrying carbapenemases (KPC-2), extended-spectrum β-lactamases (CTX-M) and plasmid-mediated quinolone resistance (PMQR) genes in urban lakes and reservoirs, in Southeastern Brazil. In this regard, the detection of hospital-associated lineages of KPC-2-producing Klebsiella pneumoniae belonging to the international clonal complex CC258 (ST11) and CTX-M-15-producing Escherichia coli belonging to the international CC10 (ST617), in an urban lake, is reported for the first time. Whole genome sequencing (WGS) analysis of KPC-2-producing K. pneumoniae ST11 revealed that bla_KPC-2 gene was carried by an IncN plasmid on a Tn4401b element. This study support that aquatic environments with public access can act as reservoirs of clinically important MDR bacteria, constituting a potential risk to human and animal health. On the other hand, the detection of high-risk clones highlights the extra-hospital spread of clinically significant bacteria into urban aquatic environments.

Comparative Genomic Analysis of Globally Dominant ST131 Clone with Other Epidemiologically Successful Extraintestinal Pathogenic Escherichia coli (ExPEC) Lineages

Escherichia coli sequence type 131 (ST131), a pandemic clone responsible for the high incidence of extraintestinal pathogenic E. coli (ExPEC) infections, has been known widely for its contribution to the worldwide dissemination of multidrug resistance. Although other ExPEC-associated and extended-spectrum-β-lactamase (ESBL)-producing E. coli clones, such as ST38, ST405, and ST648 have been studied widely, no comparative genomic data with respect to other genotypes exist for ST131. In this study, comparative genomic analysis was performed for 99 ST131 E. coli strains with 40 genomes from three other STs, including ST38 (n = 12), ST405 (n = 10), and ST648 (n = 18), and functional studies were performed on five in-house strains corresponding to the four STs. Phylogenomic analysis results from this study corroborated with the sequence type-specific clonality. Results from the genome-wide resistance profiling confirmed that all strains were inherently multidrug resistant. ST131 genomes showed unique virulence profiles, and analysis of mobile genetic elements and their associated methyltransferases (MTases) has revealed that several of them were missing from the majority of the non-ST131 strains. Despite the fact that non-ST131 strains lacked few essential genes belonging to the serum resistome, the in-house strains representing all four STs demonstrated similar resistance levels to serum antibactericidal activity. Core genome analysis data revealed that non-ST131 strains usually lacked several ST131-defined genomic coordinates, and a significant number of genes were missing from the core of the ST131 genomes. Data from this study reinforce adaptive diversification of E. coli strains belonging to the ST131 lineage and provide new insights into the molecular mechanisms underlying clonal diversification of the ST131 lineage.

E. coli, particularly the ST131 extraintestinal pathogenic E. coli (ExPEC) lineage, is an important cause of community- and hospital-acquired infections, such as urinary tract infections, surgical site infections, bloodstream infections, and sepsis. The treatment of infections caused by ExPEC has become very challenging due to the emergence of resistance to the first-line as well as the last-resort antibiotics. This study analyzes E. coli ST131 against three other important and globally distributed ExPEC lineages (ST38, ST405, and ST648) that also produced extended-spectrum β-lactamase (ESBL). This is perhaps the first study that employs the high-throughput whole-genome sequence-based approach to compare and study the genomic features of these four ExPEC lineages in relation to their functional properties. Findings from this study highlight the differences in the genomic coordinates of ST131 with respect to the other STs considered here. Results from this comparative genomics study can help in advancing the understanding of ST131 evolution and also offer a framework towards future developments in pathogen identification and targeted therapeutics to prevent diseases caused by this pandemic E. coli ST131 clone.

Plasmid-Mediated Novel blaNDM-17 Gene Encoding a Carbapenemase with Enhanced Activity in a Sequence Type 48 Escherichia coli Strain

Carbapenem-resistant Enterobacteriaceae (CRE) have spread worldwide, leaving very few treatment options available. New Delhi metallo-beta-lactamase (NDM) is the main carbapenemase mediating CRE resistance and is of increasing concern. NDM-positive Enterobacteriaceae of human origin are frequently identified; however, the emergence of NDM, and particularly novel variants, in bacteria of food animal origin has never been reported. Here, we characterize a novel NDM variant (assigned NDM-17) identified in a β-lactam-resistant sequence type 48 (ST48) Escherichia coli strain that was isolated from a chicken in China. Compared to NDM-1, NDM-17 had three amino acid substitutions (V88L, M154L, and E170K) that confer significantly enhanced carbapenemase activity. Compared to NDM-5, NDM-17 had only one amino acid substitution (E170K) and slightly increased isolate resistance to carbapenem, as indicated by increased MIC values. The gene encoding NDM-17 (bla_NDM-17) was located on an IncX3 plasmid, which was readily transferrable to recipient E. coli strain J53 by conjugation, suggesting the possibility of the rapid dissemination of bla_NDM-17 Enzyme kinetics showed that NDM-17 could hydrolyze all β-lactams tested, except for aztreonam, and had a significantly higher affinity for all β-lactams tested than did NDM-5. The emergence of this novel NDM variant could pose a threat to public health because of its transferability and enhanced carbapenemase activity.

Antimicrobial Resistance and Molecular Epidemiology of ESBL-Producing Escherichia coli Isolated from Outpatients in Town Hospitals of Shandong Province, China

This study aimed to investigate antimicrobial resistance and molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) isolated from outpatients in town hospitals of Shandong province, China. Antimicrobial susceptibility of ESBL-producing E. coli was tested using the disk diffusion and resistance genes encoding for β-lactamases (bla_TEM, bla_CTXM, and bla_SHV) were detected by polymerase chain reaction (PCR). Multilocus sequence typing (ST) of ESBL-producing E. coli was analyzed in this study. Our results showed that of 320 E. coli isolates, 201 carried ESBL genes (201/320, 62.8%), and these isolates all carried bla_CTX-M genes, the most common being bla_CTX-M-14 (116/201, 57.7%), followed by bla_CTX-M-55 (47/201, 23.4%) and bla_CTX-M-15 (31/201, 15.4%). ESBL-producing E. coli exhibited highly resistant to penicillin derivatives, fluoroquinolones, folate pathway inhibitors, and third-generation cephalosporins, but no carbapenem-resistant isolates were found in this study. Forty-two STs were found among the 201 ESBL-producing E. coli, and the most common ST was ST131 (27/201, 13.4%), followed by ST405 (19/201, 9.5%) and ST69 (15/201, 7.5%). Taken together, a high isolation rate of ESBL-producing E. coli (62.8%) was found among outpatients in town hospitals. bla_CTX-M gene was most dominant and was composed of a variety of subtypes. No dominant ST was detected among ESBL-producing E. coli, indicating that these ESBL-producing E. coli isolates derive from different clones.

Antibiotic Susceptibilities and Genetic Characteristics of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Isolates from Stools of Pediatric Diarrhea Patients in Surabaya, Indonesia

The purpose of this study was to investigate extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from pediatric (aged 0 to 3 years) diarrhea patients in Surabaya, Indonesia, where this kind of survey is rare; our study included assessment of their antibiotic susceptibilities, as well as ESBL typing, multilocus sequence typing (MLST), and diarrheagenic E. coli (DEC)-typing. ESBL-producing E. coli were detected in 18.8% of all the samples. Many ESBL-producing E. coli had significantly lower susceptibility to gentamicin (p ＜ 0.0001) and the quinolones nalidixic acid (p＝0.004) and ciprofloxacin (p ＜ 0.0001) than non-producers. In ESBL-producing E. coli, 84.0% of strains expressed CTX-M-15 alone or in combination with other ESBL types. MLST revealed that 24.0% of ESBL-producers had sequence type 617, all of which expressed the CTX-M-15 gene; we also detected expression of 3 DEC-related genes: 2 enteroaggregative E. coli genes and 1 enteropathogenic E. coli gene. In conclusion, CTX-M-15-type ESBL-producing E. coli ST617 appear to have spread to Indonesia.

Sequence Type 48 Escherichia coli Carrying the blaCTX-M-1 IncI1/ST3 Plasmid in Drinking Water in France

Drinking water has rarely been recognized as a source of antimicrobial resistance for humans, and only in low-income countries. Here, a sequence type 48 Escherichia coli isolate carrying the blaCTX-M-1 IncI1/ST3 plasmid was recovered from drinking water in France. This plasmid was similar to other blaCTX-M-1 IncI1/ST3 plasmids found previously in animals and humans. Our findings highlight the possible human transfer of extended-spectrum β-lactamase (ESBL) genes through drinking water in high-income countries.

Reservoirs of Extraintestinal Pathogenic Escherichia coli

Several potential reservoirs for the Escherichia coli strains that cause most human extraintestinal infections (extraintestinal pathogenic E. coli; ExPEC) have been identified, including the human intestinal tract and various non-human reservoirs, such as companion animals, food animals, retail meat products, sewage, and other environmental sources. Understanding ExPEC reservoirs, chains of transmission, transmission dynamics, and epidemiologic associations will assist greatly in finding ways to reduce the ExPEC-associated disease burden. The need to clarify the ecological behavior of ExPEC is all the more urgent because environmental reservoirs may contribute to acquisition of antimicrobial resistance determinants and selection for and amplification of resistant ExPEC. In this chapter, we review the evidence for different ExPEC reservoirs, with particular attention to food and food animals, and discuss the public health implications of these reservoirs for ExPEC dissemination and transmission.

Escherichia coli β-Lactamases: What Really Matters

Escherichia coli strains belonging to diverse pathotypes have increasingly been recognized as a major public health concern. The β-lactam antibiotics have been used successfully to treat infections caused by pathogenic E. coli. However, currently, the utility of β-lactams is being challenged severely by a large number of hydrolytic enzymes – the β-lactamases expressed by bacteria. The menace is further compounded by the highly flexible genome of E. coli, and propensity of resistance dissemination through horizontal gene transfer and clonal spread. Successful management of infections caused by such resistant strains requires an understanding of the diversity of β-lactamases, their unambiguous detection, and molecular mechanisms underlying their expression and spread with regard to the most relevant information about individual bacterial species. Thus, this review comprises first such effort in this direction for E. coli, a bacterial species known to be associated with production of diverse classes of β-lactamases. The review also highlights the role of commensal E. coli as a potential but under-estimated reservoir of β-lactamases-encoding genes.

Epidemic potential of Escherichia coli ST131 and Klebsiella pneumoniae ST258: a systematic review and meta-analysis

OBJECTIVES

Observational studies have suggested that Escherichia coli sequence type (ST) 131 and Klebsiella pneumoniae ST258 have hyperendemic properties. This would be obvious from continuously high incidence and/or prevalence of carriage or infection with these bacteria in specific patient populations. Hyperendemicity could result from increased transmissibility, longer duration of infectiousness, and/or higher pathogenic potential as compared with other lineages of the same species. The aim of our research is to quantitatively estimate these critical parameters for E. coli ST131 and K. pneumoniae ST258, in order to investigate whether E. coli ST131 and K. pneumoniae ST258 are truly hyperendemic clones.

PRIMARY OUTCOME MEASURES

A systematic literature search was performed to assess the evidence of transmissibility, duration of infectiousness, and pathogenicity for E. coli ST131 and K. pneumoniae ST258. Meta-regression was performed to quantify these characteristics.

RESULTS

The systematic literature search yielded 639 articles, of which 19 data sources provided information on transmissibility (E. coli ST131 n=9; K. pneumoniae ST258 n=10)), 2 on duration of infectiousness (E. coli ST131 n=2), and 324 on pathogenicity (E. coli ST131 n=285; K. pneumoniae ST258 n=39). Available data on duration of carriage and on transmissibility were insufficient for quantitative assessment. In multivariable meta-regression E. coli isolates causing infection were associated with ST131, compared to isolates only causing colonisation, suggesting that E. coli ST131 can be considered more pathogenic than non-ST131 isolates. Date of isolation, location and resistance mechanism also influenced the prevalence of ST131. E. coli ST131 was 3.2 (95% CI 2.0 to 5.0) times more pathogenic than non-ST131. For K. pneumoniae ST258 there were not enough data for meta-regression assessing the influence of colonisation versus infection on ST258 prevalence.

CONCLUSIONS

With the currently available data, it cannot be confirmed nor rejected, that E. coli ST131 or K. pneumoniae ST258 are hyperendemic clones.

Carriage of Extended-Spectrum Beta-Lactamase-Plasmids Does Not Reduce Fitness but Enhances Virulence in Some Strains of Pandemic E. coli Lineages

Pathogenic ESBL-producing E. coli lineages occur frequently worldwide, not only in a human health context but in animals and the environment, also in settings with low antimicrobial pressures. This study investigated the fitness costs of ESBL-plasmids and their influence on chromosomally encoded features associated with virulence, such as those involved in the planktonic and sessile behaviors of ST131 and ST648 E. coli. ESBL-plasmid-carrying wild-type E. coli strains, their corresponding ESBL-plasmid-“cured” variants (PCV), and complementary ESBL-carrying transformants were comparatively analyzed using growth curves, Omnilog® phenotype microarray (PM) assays, macrocolony and biofilm formation, swimming motility, and RNA sequence analysis. Growth curves and PM results pointed toward similar growth and metabolic behaviors among the strains. Phenotypic differences in some strains were detected, including enhanced curli fimbriae and/or cellulose production as well as a reduced swimming capacity of some ESBL-carrying strains, as compared to their respective PCVs. RNA sequencing mostly confirmed the phenotypic results, suggesting that the chromosomally encoded csgD pathway is a key factor involved. These results contradict the hypothesis that ESBL-plasmid-carriage leads to a fitness loss in ESBL-carrying strains. Instead, the results indicate an influence of some ESBL-plasmids on chromosomally encoded features associated with virulence in some E. coli strains. In conclusion, apart from antibiotic resistance selective advantages, ESBL-plasmid-carriage may also lead to enhanced virulence or adaption to specific habitats in some strains of pandemic ESBL-producing E. coli lineages.

Asymptomatic faecal carriage of ESBL producing enterobacteriaceae in Hungarian healthy individuals and in long-term care applicants: A shift towards CTX-M producers in the community

Background Faecal carriage of extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae in healthy individuals was examined and compared to previous results obtained in such individuals a few years earlier. Methods Faecal samples from 779 individuals screened for employment purposes and from 225 applicants to long-term care (LTC) were screened between November 2013 and May 2014. Results The overall rate of faecal carriage was 3.0% (30/1004). The carriage rate was significantly higher in applicants for LTC (5.3% vs 2.3%; p = 0.019). All isolates carried CTX-M ESBLs, with an overwhelming dominance of blaCTX-M-15 (84.4%) in both groups and in both E. coli and Klebsiella pneumoniae. Conclusions The prevalences were comparable to those in the earlier study, but a marked decrease of the diversity of ESBL genes in E. coli from the employment screening group was found, suggesting that the ESBL-producing isolates originating from diverse sources are being replaced by highly successful blaCTX-M-15 producing strains.

Heat resistance in extended-spectrum beta-lactamase-producing Escherichia coli may favor environmental survival in a hospital setting

Nosocomial infections caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are a major concern worldwide. There is an urgent need to identify bacterial factors promoting survival and persistence of these organisms in the nosocomial environment. Here, we describe the presence of a gene cluster, containing the Clp ATPase ClpK, within a collection of Danish ESBL-producing E. coli isolates. The cluster conferred thermoprotection upon the isolates, and thus might facilitate survival on medical devices exposed to semi-high temperatures in a hospital setting.

The Widespread Presence of a Multidrug-Resistant Escherichia coli ST131 Clade among Community-Associated and Hospitalized Patients

BACKGROUND & AIMS

The extent of entry of multidrug-resistant Escherichia coli from the community into the hospital and subsequent clonal spread amongst patients is unclear. To investigate the extent and direction of clonal spread of these bacteria within a large teaching hospital, we prospectively genotyped multidrug-resistant E. coli obtained from community- and hospital associated patient groups and compared the distribution of diverse genetic markers.

METHODS

A total of 222 E. coli, classified as multi-drug resistant according to national guidelines, were retrieved from both screening (n = 184) and non-screening clinical cultures (n = 38) from outpatients and patients hospitalized for various periods. All isolates were routinely genotyped using an amplified fragment length polymorphism (AFLP) assay and real-time PCR for CTX-M genes. Multi-locus sequence typing was additionally performed to confirm clusters. Based on demographics, patients were categorized into two groups: patients that were not hospitalized or less than 72 hours at time of strain isolation (group I) and patients that were hospitalized for at least 72 hours (group II).

RESULTS

Genotyping showed that most multi-drug resistant E. coli either had unique AFLP profiles or grouped in small clusters of maximally 8 isolates. We identified one large ST131 clade comprising 31% of all isolates, containing several AFLP clusters with similar profiles. Although different AFLP clusters were found in the two patient groups, overall genetic heterogeneity was similar (35% vs 28% of isolates containing unique AFLP profiles, respectively). In addition, similar distributions of CTX-M groups, including CTX-M 15 (40% and 44% of isolates in group I and II, respectively) and ST131 (32% and 30% of isolates, respectively) were found.

CONCLUSION

We conclude that multi-drug resistant E. coli from the CTX-M 15 associated lineage ST131 are widespread amongst both community- and hospital associated patient groups, with similar genetic diversity and similar distributions of genetic markers.

[Prevalence and risk factors for extended-spectrum β-lactamase-producing Escherichia coli causing community-onset urinary tract infections in Colombia]

INTRODUCTION

Urinary tract infections (UTI) are common in the community. However, information of resistant isolates in this context is limited in Latin America. This study aims to determine the prevalence and risk factors associated with community-onset UTI (CO-UTI) caused by extended-spectrum β-lactamase (ESBL)-Producing Escherichia coli in Colombia.

MATERIALS AND METHODS

A case-control study was conducted between August and December of 2011 in three Colombian tertiary-care institutions. All patients who were admitted to the Emergency Department with a probable diagnosis of CO-UTI were invited to participate. All participating patients were asked for a urine sample. ESBL confirmatory test, antibiotic susceptibility, and molecular epidemiology were performed in these E.coli isolates (Real Time-PCR for bla genes, repetitive element palindromic PCR [rep-PCR], multilocus sequence typing [MLST] and virulence factors by PCR). Clinical and epidemiological information was recorded, and a statistical analysis was performed.

RESULTS

Of the 2124 recruited patients, 629 had a positive urine culture, 431 of which grew E.coli; 54 were positive for ESBL, of which 29 were CTX-M-15. The majority of ESBL isolates were susceptible to ertapenem, phosphomycin and amikacin. Complicated UTI was strongly associated with ESBL-producing E.coli infections (OR=3.89; 95%CI: 1.10-13.89; P=.03). CTX-M-15-producing E.coli showed 10 different pulsotypes, 65% were PT1 or PT4, and corresponded to ST131. Most of these isolates had 8 out of the 9 analysed virulence factors.

DISCUSSION

E.coli harbouring bla_CTX-M-15 associated with ST131 is still frequent in Colombia. The presence of complicated CO-UTI increases the risk of ESBL-producing E.coli, and must be taken into account in order to provide an adequate empirical therapy.

Extended-spectrum ß-Lactamase-producing Enterobacteriaceae as a Common Cause of Urinary Tract Infections in Sri Lanka

Background

Extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-PE) are increasingly reported as pathogens in urinary tract infections (UTIs). However, in Sri Lanka, the clinical and molecular epidemiology of ESBL-PE implicated in UTIs has not been well described.

Materials and Methods

We conducted prospective, laboratory-based surveillance from October to December 2013 at a tertiary care hospital in southern Sri Lanka and enrolled patients ≥1 year of age with clinically relevant UTIs due to ESBL-PE. Isolate identity, antimicrobial drug susceptibility, and ESBL production were determined. Presence of ß-lactamase genes, bla_SHV, bla_TEM, and bla_CTX-M, was identified by polymerase chain reaction.

Results

During the study period, Enterobacteriaceae were detected in 184 urine samples, with 74 (40.2%) being ESBL producers. Among 47 patients with ESBL-PE who had medical records available, 38 (80.9%) had clinically significant UTIs. Most UTIs (63.2%) were community acquired and 34.2% were in patients with diabetes. Among 36 cultured ESBL-PE isolates, significant susceptibility (>80%) was only retained to amikacin and the carbapenems. The group 1 bla_CTX-M gene was present in 90.0% of Escherichia coli isolates and all Klebsiella pneumoniae and Enterobacter cloacae isolates. The bla_SHV and bla_TEM genes were more common in K. pneumoniae (75% and 50%) and E. cloacae (50% and 50%) isolates than in E. coli (10% and 20%) isolates, respectively.

Conclusion

The majority of UTIs caused by ESBL-PE were acquired in the community and due to organisms carrying the group 1 CTX-M ß-lactamase. Further epidemiologic studies of infections due to ESBL-PE are urgently needed to better prevent and treat these infections in South Asia.

Multidrug-Resistant and Extended Spectrum Beta-Lactamase-Producing Escherichia coli in Dutch Surface Water and Wastewater

OBJECTIVE

The goal of the current study was to gain insight into the prevalence and concentrations of antimicrobial resistant (AMR) Escherichia coli in Dutch surface water, and to explore the role of wastewater as AMR contamination source.

METHODS

The prevalence of AMR E. coli was determined in 113 surface water samples obtained from 30 different water bodies, and in 33 wastewater samples obtained at five health care institutions (HCIs), seven municipal wastewater treatment plants (mWWTPs), and an airport WWTP. Overall, 846 surface water and 313 wastewater E. coli isolates were analysed with respect to susceptibility to eight antimicrobials (representing seven different classes): ampicillin, cefotaxime, tetracycline, ciprofloxacin, streptomycin, sulfamethoxazole, trimethoprim, and chloramphenicol.

RESULTS

Among surface water isolates, 26% were resistant to at least one class of antimicrobials, and 11% were multidrug-resistant (MDR). In wastewater, the proportions of AMR/MDR E. coli were 76%/62% at HCIs, 69%/19% at the airport WWTP, and 37%/27% and 31%/20% in mWWTP influents and effluents, respectively. Median concentrations of MDR E. coli were 2.2×10(2), 4.0×10(4), 1.8×10(7), and 4.1×10(7) cfu/l in surface water, WWTP effluents, WWTP influents and HCI wastewater, respectively. The different resistance types occurred with similar frequencies among E. coli from surface water and E. coli from municipal wastewater. By contrast, among E. coli from HCI wastewater, resistance to cefotaxime and resistance to ciprofloxacin were significantly overrepresented compared to E. coli from municipal wastewater and surface water. Most cefotaxime-resistant E. coliisolates produced ESBL. In two of the mWWTP, ESBL-producing variants were detected that were identical with respect to phylogenetic group, sequence type, AMR-profile, and ESBL-genotype to variants from HCI wastewater discharged onto the same sewer and sampled on the same day (A1/ST23/CTX-M-1, B23/ST131/CTX-M-15, D2/ST405/CTX-M-15).

CONCLUSION

In conclusion, our data show that MDR E. coli are omnipresent in Dutch surface water, and indicate that municipal wastewater significantly contributes to this occurrence.

Evaluation of a Method Using Three Genomic Guided Escherichia coli Markers for Phylogenetic Typing of E. coli Isolates of Various Genetic Backgrounds

Genotyping and characterization of bacterial isolates are essential steps in the identification and control of antibiotic-resistant bacterial infections. Recently, one novel genotyping method using three genomic guided Escherichia coli markers (GIG-EM), dinG, tonB, and dipeptide permease (DPP), was reported. Because GIG-EM has not been fully evaluated using clinical isolates, we assessed this typing method with 72 E. coli collection of reference (ECOR) environmental E. coli reference strains and 63 E. coli isolates of various genetic backgrounds. In this study, we designated 768 bp of dinG, 745 bp of tonB, and 655 bp of DPP target sequences for use in the typing method. Concatenations of the processed marker sequences were used to draw GIG-EM phylogenetic trees. E. coli isolates with identical sequence types as identified by the conventional multilocus sequence typing (MLST) method were localized to the same branch of the GIG-EM phylogenetic tree. Sixteen clinical E. coli isolates were utilized as test isolates without prior characterization by conventional MLST and phylogenetic grouping before GIG-EM typing. Of these, 14 clinical isolates were assigned to a branch including only isolates of a pandemic clone, E. coli B2-ST131-O25b, and these results were confirmed by conventional typing methods. Our results suggested that the GIG-EM typing method and its application to phylogenetic trees might be useful tools for the molecular characterization and determination of the genetic relationships among E. coli isolates.

Nationwide high prevalence of CTX-M and an increase of CTX-M-55 in Escherichia coli isolated from patients with community-onset infections in Chinese county hospitals

BACKGROUND

In order to investigate the epidemiology, molecular characteristics, and distribution of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Escherichia coli from community-onset infections in Chinese county hospitals.

METHODS

E. coli isolates were collected from patients with community-onset infections in 30 county hospitals. ESBL activity was confirmed by double-disc diffusion. Genetic confirmation and molecular typing of ESBL- and AmpC-producing isolates was determined by PCR and DNA sequencing. ESBL-positive isolates were further characterised by multi-locus sequence typing.

RESULTS

Of 550 E. coli isolates, 256 (46.5%) carried ESBL genes and all were of the CTX-M type. The prevalence of ESBL-producing strains varied from 30.2% to 57.0% across different regions of China. Overall, 12 bla CTX-M subtypes were detected; the most abundant were bla CTX-M-14 (163/256 isolates, 64.5%), bla CTX-M-55 (47/256, 18.4%), and bla CTX-M-15 (31/256, 12.1%). CMY-2-like AmpC β-lactamases were detected in 11 strains, three of which co-existed with bla CTX-M. A total of 64 sequence types (STs) were detected in 256 ESBL-producing strains, including nine that were new. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%).

CONCLUSIONS

This study revealed that the widespread prevalence of ESBLs among outpatient infections has reached a high level in county hospitals. The CTX-M genotype was most dominant, comprising a variety of subtypes. This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China. No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.

Recombination blurs phylogenetic groups routine assignment in Escherichia coli: setting the record straight

The characterization of population structures plays a main role for understanding outbreaks and the dynamics of bacterial spreading. In Escherichia coli, the widely used combination of multiplex-PCR scheme together with goeBURST has some limitations. The purpose of this study is to show that the combination of different phylogenetic approaches based on concatenated sequences of MLST genes results in a more precise assignment of E. coli phylogenetic groups, complete understanding of population structure and reconstruction of ancestral clones. A collection of 80 Escherichia coli strains of different origins was analyzed following the Clermont and Doumith's multiplex-PCR schemes. Doumith's multiplex-PCR showed only 1.7% of misassignment, whereas Clermont's-2000 protocol reached 14.0%, although the discrepancies reached 30% and 38.7% respectively when recombinant C, F and E phylogroups were considered. Therefore, correct phylogroup attribution is highly variable and depends on the clonal composition of the sample. As far as population structure of these E. coli strains, including 48 E. coli genomes from GenBank, goeBURST provides a quite dispersed population structure; whereas NeighborNet approach reveals a complex population structure. MLST-based eBURST can infer different founder genotypes, for instance ST23/ST88 could be detected as the founder genotypes for STC23; however, phylogenetic reconstructions might suggest ST410 as the ancestor clone and several evolutionary trajectories with different founders. To improve our routine understanding of E. coli molecular epidemiology, we propose a strategy based on three successive steps; first, to discriminate three main groups A/B1/C, D/F/E and B2 following Doumith's protocol; second, visualization of population structure based on MLST genes according to goeBURST, using NeighborNet to establish more complex relationships among STs; and third, to perform, a cost-free characterization of evolutionary trajectories in variants emerging along the clonal expansion using parsimony methods of phylogenetic analysis.

Molecular characterization of Escherichia coli isolates from patients with urinary tract infections in Palestine

Antibiotic resistance of Escherichia coli isolated from urinary tract infections (UTIs) is increasing worldwide. A total of 41 E. coli isolates were obtained from urine samples from hospitalized patients with a UTI in three hospitals in the northern districts of the West Bank, Palestine during March and June 2011. Resistance rates were: erythromycin (95 %), trimethoprim–sulfamethoxazole (59 %), ciprofloxacin (56 %), gentamicin (27 %), imipenem (22 %), amoxicillin (93 %), amoxicillin–clavulanic acid (32 %), ceftazidime (66 %) and cefotaxime (71 %). No meropenem-resistant isolates were identified in this study. Among the isolates, phylogenetic group B2 was observed in 13 isolates, D in 12 isolates, A in 11 isolates and B1 in five isolates. Thirty-five of the isolates were positive for an extended-spectrum β-lactamase phenotype. Among these isolates, the bla CTX-M gene was detected in 25, and eight harboured the bla TEM gene. None of the isolates contained the bla SHV gene. Transformation experiments indicated that some of the β-lactamase genes (i.e. bla CTX-M and bla TEM) with co-resistance to erythromycin and gentamicin were plasmid encoded and transmissible. Apart from this, enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) revealed that the 41 isolates were genetically diverse and comprised a heterogeneous population with 11 ERIC-PCR profiles at a 60 % similarity level.

Molecular characteristics of extended-spectrum β-lactamase-producing Escherichia coli in Riyadh: emergence of CTX-M-15-producing E. coli ST131

BACKGROUND

The prevalence of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) has increased recently. The aim of this study was to further characterise and to assess the occurrence of ESBL-EC in Riyadh, to use pulsed field gel electrophoresis (PFGE) typing to investigate the epidemiology of ESBL-EC and to determine the prevalence of ST131 in ESBL-EC.

METHODS

A total of 152 E. coli isolates were collected at a tertiary hospital in Riyadh from September 2010 to June 2011. Genotypic and phenotypic methods were used to characterise ESBLs. PFGE was used to determine genetic relatedness. Detection of ST131 and CTX-M-like ESBLs was performed using real-time PCR.

RESULTS

Of 152 strains, 31 were positive for ESBLs by phenotypic methods. The blaCTX-M-15 gene was highly prevalent (30/31 strains, 96.77%) among the 31 ESBL-positive E. coli strains. The blaCTX-M-27 gene was detected in one strain. Twenty (64.5%) out of 31 of ESBL-EC were ST131. PFGE revealed 29 different pulsotypes.

CONCLUSIONS

Our study documented the high prevalence of ESBLs in E. coli isolates, with CTX-M-15 as the predominant ESBL gene. ST131 clone producing CTX-M-15 has a major presence in our hospital. The high prevalence of CTX-M producers was not due to the spread of a single clone. To the best of our knowledge, this study represents the first report of CTX-M-15 and CTX-M-27 β-lactamases and the detection of the ST131 clone in Saudi E. coli isolates.

Epidemiology of extended-spectrum β-lactamase-producing Escherichia coli in Sweden 2007-2011

Extended-spectrum β-lactamase (ESBL) -producing Enterobacteriaceae have been notifiable according to the Swedish Communicable Disease Act since 2007. A major increase in the number of cases has been observed, with 2099 cases in 2007 and 7225 cases in 2012. The majority of the isolates are Escherichia coli. Additionally, Swedish data on the prevalence of ESBL-producing invasive isolates of E. coli are available through EARS-Net, and through biannual point prevalence studies, where molecular characterization of isolates from the entire country is carried out. This paper describes major trends in the Swedish epidemiology of ESBL-producing E. coli in the period 2007-2012. Isolates from the point prevalence studies were subjected to antimicrobial susceptibility testing, ESBL genotyping, pulsed-field gel electrophoresis, multi-locus sequence typing and phylogenetic grouping with PCR. The distribution of sequence types, resistance genes and susceptibility levels were all stable over the three study periods. The dominating resistance gene conferring ESBL was blaCTX -M-15 , found in 54-58% of the isolates. ST131 represented 34-38% of the isolates. Other major sequence types were ST38, ST69, ST405, ST617 and ST648, each representing 2-6% of the isolates. Phylogenetic group B2 was the most common, and was observed in 41-47% of the isolates. However, among ST131 isolates the B2 phylogenetic group represented 90-98% of the isolates. The most important epidemiological difference seen over time was that the median age of infected women decreased from 62 to 52 years (p <0.0001) and infected men from 67 to 64 years. A potential explanation might be the shift towards a higher proportion of community-acquired infections in individuals lacking comorbidities.

Detection of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli on flies at poultry farms

In the Netherlands, extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli bacteria are highly prevalent in poultry, and chicken meat has been implicated as a source of ESBL-producing E. coli present in the human population. The current study describes the isolation of ESBL-producing E. coli from house flies and blow flies caught at two poultry farms, offering a potential alternative route of transmission of ESBL-producing E. coli from poultry to humans. Overall, 87 flies were analyzed in 19 pools. ESBL-producing E. coli bacteria were detected in two fly pools (10.5%): a pool of three blow flies from a broiler farm and a pool of eight house flies from a laying-hen farm. From each positive fly pool, six isolates were characterized and compared with isolates obtained from manure (n = 53) sampled at both farms and rinse water (n = 10) from the broiler farm. Among six fly isolates from the broiler farm, four different types were detected with respect to phylogenetic group, sequence type (ST), and ESBL genotype: A0/ST3519/SHV-12, A1/ST10/SHV-12, A1/ST58/SHV-12, and B1/ST448/CTX-M-1. These types, as well as six additional types, were also present in manure and/or rinse water at the same farm. At the laying-hen farm, all fly and manure isolates were identical, carrying blaTEM-52 in an A1/ST48 genetic background. The data imply that flies acquire ESBL-producing E. coli at poultry farms, warranting further evaluation of the contribution of flies to dissemination of ESBL-producing E. coli in the community.

Extraintestinal pathogenic Escherichia coli: an update on antimicrobial resistance, laboratory diagnosis and treatment

Escherichia coli remains one of the most frequent causes of nosocomial and community-acquired bacterial infections including urinary tract infections, enteric infections and systemic infections in humans. Extraintestinal pathogenic E. coli (ExPEC) had emerged during the 2000s as an important player in the resistance to antibiotics, especially to the cephalosporins and fluoroquinolones. Most importantly, among ExPEC is the increasing recognition of isolates producing 'newer β-lactamases' that consist of plasmid-mediated AmpC β-lactamases (e.g., CMY), extended-spectrum β-lactamases (e.g., CTX-M) and carbapenemases (e.g., New Delhi metallo-β-lactamase, Klebsiella pneumonaie carbapenemase and OXA-48). This review will highlight recent aspects on antimicrobial resistance in ExPEC, including the laboratory detection of these isolates, and describe some treatment options for infections due to antimicrobial-resistant isolates.

CTX-M-type β-lactamases: a successful story of antibiotic resistance

Production of extended-spectrum β-lactamases (ESBLs) is the principal mechanism of resistance to oxyimino-cephalosporins evolved by members of the family Enterobacteriaceae. Among the several ESBLs emerged among clinical pathogens, the CTX-M-type enzymes have proved the most successful in terms of promiscuity and diffusion in different epidemiological settings, where they have largely replaced and outnumbered other types of ESBLs. Originated by the capture and mobilization of chromosomal β-lactamase genes of strains of Kluyvera species, the blaCTX-M genes have become associated with a variety of mobile genetic elements that have mediated rapid and efficient inter-replicon and cell-to-cell dissemination involving highly successful enterobacterial lineages (e.g. Escherichia coli ST131 and ST405, or Klebsiella pneumoniae CC11 and ST147) to yield high-risk multiresistant clones that have spread on a global scale. The CTX-Mβ-lactamase lineage exhibits a striking plasticity, with a large number of allelic variants belonging in several sublineages, which can be associated with functional heterogeneity of clinical relevance. This review article provides an update on CTX-M-type ESBLs, with focus on structural and functional diversity, epidemiology and clinical significance.

Extended-spectrum cephalosporin-resistant Gram-negative organisms in livestock: an emerging problem for human health?

Escherichia coli, Salmonella spp. and Acinetobacter spp. are important human pathogens. Serious infections due to these organisms are usually treated with extended-spectrum cephalosporins (ESCs). However, in the past two decades we have faced a rapid increasing of infections and colonization caused by ESC-resistant (ESC-R) isolates due to production of extended-spectrum-β-lactamases (ESBLs), plasmid-mediated AmpCs (pAmpCs) and/or carbapenemase enzymes. This situation limits drastically our therapeutic armamentarium and puts under peril the human health. Animals are considered as potential reservoirs of multidrug-resistant (MDR) Gram-negative organisms. The massive and indiscriminate use of antibiotics in veterinary medicine has contributed to the selection of ESC-R E. coli, ESC-R Salmonella spp. and, to less extent, MDR Acinetobacter spp. among animals, food, and environment. This complex scenario is responsible for the expansion of these MDR organisms which may have life-threatening clinical significance. Nowadays, the prevalence of food-producing animals carrying ESC-R E. coli and ESC-R Salmonella (especially those producing CTX-M-type ESBLs and the CMY-2 pAmpC) has reached worryingly high values. More recently, the appearance of carbapenem-resistant isolates (i.e., VIM-1-producing Enterobacteriaceae and NDM-1 or OXA-23-producing Acinetobacter spp.) in livestock has even drawn greater concerns. In this review, we describe the aspects related to the spread of the above MDR organisms among pigs, cattle, and poultry, focusing on epidemiology, molecular mechanisms of resistance, impact of antibiotic use, and strategies to contain the overall problem. The link and the impact of ESC-R organisms of livestock origin for the human scenario are also discussed.

Virulence potential and adherence properties of Escherichia coli that produce CTX-M and NDM β-lactamases

The success of certain sequence types such as ST131 that produce CTX-M or NDM β-lactamases, and ST405 that produce CTX-M β-lactamases, among extraintestinal Escherichia coli (ExPEC) had previously been linked to a combination of antimicrobial resistance and certain virulence factors. The adherence properties of these sequence types to gastro-intestinal epithelial cells had not been investigated. A study was therefore designed to investigate the phylogenetic groups, virulence factors and adherence properties of E. coli sequence types ST101, ST131 and ST405 that produce CTX-M-15 and NDM-1. Our results show that ST131 was positive for phylogenetic group B2, ST101 for B1 and ST404 for D. ST131 had more virulence factors than ST101 or ST405. Interestingly, ST101 adhered more avidly to HEp-2 and Caco-2 cells than did ST131 and ST405. Our study showed that adherence to gastro-intestinal cells did not seem to play an important role in the worldwide epidemiological success of ST131 and ST405. The exact role of ExPEC-associated virulence genes is unknown and it is unlikely that one set of factors determines the virulence properties and epidemiological success of certain sequence types. Future investigations should be undertaken to study the microbiological and ecological factors that make certain sequence types among ExPEC such successful pathogens.

Detection of Salmonella enterica isolates producing CTX-M Cephalosporinase in U.S. livestock populations

We report the detection of Salmonella carrying bla(CTX-M) in U.S. livestock populations. We identified 12 of 2,034 (0.6%) Salmonella isolates originating from turkeys, horses, and pigs from at least 6 U.S. states, all carrying bla(CTX-M-1), many on a pandemic sequence type 1 IncN plasmid.