Community-onset extended-spectrum-β-lactamase-producing Escherichia coli sequence type 131 at two Korean community hospitals: The spread of multidrug-resistant E. coli to the community via healthcare facilities

Distribution of Extended-Spectrum-β-Lactamase-Producing Diarrheagenic Escherichia coli Clonal Complex 10 Isolates from Patients with Diarrhea in the Republic of Korea

ESBL-producing E. coli is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic E. coli isolates were identified, and clonal complex (CC) 10 was the predominant clone (n = 57). This study aimed to characterize the ESBL-producing pathogenic E. coli CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 (n = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were blaCTX-M-15 (n = 31, 55%) and blaCTX-M-14 (n = 15, 27%). Most blaCTXM genes (n = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included ISEcp1 (complete or incomplete) and IS903 or orf477. Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic E. coli CC10 has been consistently isolated, with CTX-M-15-producing E. coli O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic E. coli CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing E. coli CC10 strains.

Clinical and microbiological characteristics of men with nonobstructive acute pyelonephritis: A multicenter retrospective observational study

To investigate the differences in clinical and microbiological features in men hospitalized with community-acquired (CA) and healthcare-associated (HA) nonobstructive acute pyelonephritis (APN), as well as the predictive factors associated with bacteremia.Men discharged from urological centers with nonobstructive APN were identified using an electronic medical records system. We compared the clinical and microbiological data between subjects with CA-APN and HA-APN.Of the 245 men with nonobstructive APN, 175 had CA-APN, and 70 had HA-APN. The HA group was significantly older, had a longer hospital stay, and had more underlying diseases, bacteremia, and intensive care unit admissions than the CA group. The most commonly cultured microorganism was Escherichia coli. The susceptibility of the cultured bacteria to fluoroquinolone was 68.7% in the CA group and 45.3% in the HA group (P = .005). The proportion of extended-spectrum beta-lactamase-producing bacteria was 22.7% for CA and 53.5% for HA (P < .001). The sensitivity to piperacillin/tazobactam was 94.9% for CA and 90.0% for HA, and the sensitivity to amikacin was more than 95% for both groups. The multivariate analysis revealed that an age ≥65 years and chronic liver disease were independent predictive factors for bacteremia.The incidence of antibiotic resistance and bacteremia was higher in the HA group than in the CA group. However, resistance to fluoroquinolone and the presence of extended-spectrum beta-lactamase-producing bacteria were high in both groups. Piperacillin/tazobactam and amikacin may be suitable treatment options in men with nonobstructive APN.

Risk Factors for Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Community-Onset Bloodstream Infection: Impact on Long-Term Care Hospitals in Korea

Background

The prevalence of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) in the community has increased worldwide due to multifactorial reasons. ESBL-EC bloodstream infection (BSI) complicates the decision for proper antimicrobial administration. In this multicenter study, we investigated the prevalence, risk factors, and molecular background of community-onset (CO) ESBL-EC BSI.

Methods

We included data for all episodes of ESBL-EC BSI of community origin from May 2016 to April 2017 obtained from the Korean national antimicrobial resistance surveillance system, which comprises six sentinel hospitals. Data, including previous history of admission and use of antimicrobials and medical devices before BSI, were collected, along with microbiological analysis results.

Results

Among 1,189 patients with CO BSI caused by E. coli, 316 (27%) were identified as ESBL producers. History of admission, especially to a long-term care hospital (LTCH), and previous use of β-lactams/β-lactamase inhibitors, carbapenem, lincosamide, aminoglycoside, and extended-spectrum cephalosporin were independent risk factors for CO ESBL-EC BSI; admission to an LTCH showed the highest odds ratio (3.8, 95% confidence interval 2.3-6.1). The most common genotype was CTX-M-15 (N=131, 41%), followed by CTX-M-14 (N=86, 27%). ST131 was the most common sequence type among ESBL-EC groups (57%).

Conclusions

In Korea, 27% of CO E. coli BSI were caused by ESBL producers. From perspectives of empirical treatment and infection control, history of admission to an LTCH and antimicrobial use should be noted.

Prevalence and Molecular Epidemiology of Extended-Spectrum-β-Lactamase (ESBL)-Producing Escherichia coli From Multiple Sectors of the Swine Industry in Korea: A Korean Nationwide Monitoring Program for a One Health Approach to Combat Antimicrobial Resistance

Background

One health is a flexible concept with many facets, including the environment, community, and the nosocomial super-bacteria resistance network. We investigated the molecular prevalence of extended-spectrum-β-lactamase-producing Escherichia coli (ESBL-EC) in workers, livestock, and the farm environment in Korea.

Methods

ESBL-EC isolates were obtained from samples from 19 swine farms, 35 retail stores, seven slaughterhouses, and 45 related workers throughout Korea from August 2017 to July 2018, using ChromID ESBL (BioM?rieux, Marcy l’Etoile, France) agar and enrichment broth. The presence of ESBL and mobilized colistin resistance (mcr) genes and antimicrobial resistance were determined. Clonality was evaluated with pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Results

In total, 232 ESBL-EC isolates were obtained from 1,614 non-duplicated samples (14.4% positive rate). The ESBL-EC isolates showed regional and source-related differences. bla_CTX-M-55 (N=100), bla_CTX-M-14 (N=65), bla_CTX-M-15 (N=33), and bla_CTX-M-65 (N=23) were common ESBL types. The ESBL-EC isolates showed high resistance rates for various antimicrobial classes; however, all isolates were susceptible to carbapenem. One swine-originating colistin-resistant isolate did not carry any known mcr gene. PFGE was successful for 197 of the 232 isolates, and most PFGE types were heterogeneous, except for some dominant PFGE types (O, R, T, U, and V). MLST of 88 isolates was performed for representative PFGE types; however, no dominant sequence type was observed.

Conclusions

The proportion of ESBL-EC in swine industry-related samples was significant, and the isolates harbored common clinical ESBL gene types. These molecular epidemiologic data could provide important evidence for antimicrobial-resistance control through a one health approach.

Prevalence and Molecular Epidemiology of Extended-Spectrum-β-Lactamase (ESBL)-Producing Escherichia coli from Multiple Sectors of Poultry Industry in Korea

The aim of this study was to investigate the molecular epidemiology of extended-spectrum-β-lactamase producing Escherichia coli (ESBL-EC) from poultry, the poultry farm environment, and workers in Korea. A total of 1376 non-duplicate samples were collected from 21 poultry farms, 20 retail stores, 6 slaughterhouses, and 111 workers in a nationwide study in Korea from January 2019 to August 2019. The overall positive rate of ESBL-EC was 6.8%, with variable positive rates according to sources (0.9% of worker, 5.2% of poultry, 10.0% of chicken meat, and 14.3% of environment). Common ESBL types were CTX-M-55 and CTX-M-14 in a total of 93 ESBL-EC isolates. Whole genome sequencing revealed that 84 ESBL-EC isolates had an outstanding accumulation of numerous antimicrobial resistance (AMR) genes associated with resistance to various classes of antimicrobials for human use and well-known antimicrobial gene (ARG)-carrying plasmids. Core gene multi locus sequence typing, using 2390 core genes, indicated no dominant clone or common type in each province. In conclusion, the isolation rates of ESBL-EC were not negligible in the poultry industry-related samples, sharing common ESBL types of human ESBL-EC isolates in Korea.

Non-carbapenem antimicrobial therapy in young infant with urinary tract infections caused by community-acquired extended-spectrum β-lactamase-producing Escherichia coli

BACKGROUND

The frequency of urinary tract infections (UTIs) caused by community-acquired extended-spectrum β-lactamase (CA-ESBL)-producing Enterobacteriaceae is increasing worldwide. Increased carbapenem use may lead to selection of carbapenem-resistant organisms, resulting in dire consequences for hospitals. We compared the outcomes of non-carbapenem antimicrobial therapy on UTIs caused by CA-ESBL-producing and non-producing Escherichia coli (E. coli) in infants younger than 6 months of age.

METHODS

We conducted a retrospective chart review, from January 2010 to December 2018, in infants (0-6 months old) with diagnosed UTIs caused by CA-ESBL-producing and non-producing E. coli at the Pusan National University Children's Hospital. Chart reviews were completed for patients whose urine sample had been collected using urinary catheterization. We treated all patients using non-carbapenem antimicrobials. Two weeks after therapy completion, clinical states were evaluated.

RESULTS

There were 105 and 582 patients diagnosed with UTIs caused by CA-ESBL-producing and non-producing E. coli, respectively. The mean age at diagnosis in ESBL and non-ESBL groups was 2.7 ± 1.6 and 2.8 ± 1.1 months (P = 0.711), respectively. There were no significant differences between ESBL and non-ESBL groups in the duration of fever (1.2 ± 0.5 and 1.2 ± 0.4 days, respectively, P = 0.761) or clinical cure states post therapy (101/105 and 567/582, respectively, P = 0.513).

CONCLUSION

This study found no significant differences in treatment outcomes between ESBL and non-ESBL groups treated with non-carbapenem antimicrobials. Therefore, initially administered non-carbapenem antimicrobials can be continued in patients with UTIs caused by CA-ESBL-producing E. coli who show clinical improvement.

The characteristic and relationship of Escherichia coli isolated from urine and stones in patients with calcium oxalate stones

Previous clinical studies have shown that Escherichia coli (E. coli) predominated in urine and stone culture from calcium oxalate (CaOx) stone disease. The characteristic and relationship between E. coli isolated from urine cultures (EUC) and stone cultures (ESC) are compared. 83 E. coli (33 EUC and 50 ESC, respectively) from 66 CaOx stone patients were recruited in the study. E. coli in urine and stones from those patients were assessed by antimicrobial susceptibility test, genotyping and phylogenetic grouping. Furthermore, whole genome sequencing and comparative genomic analysis in paired ESC and EUC isolated strains from eight patients were carried out. The E. coli strains from ESC and EUC were not only multidrug resistant (MDR), but also had the similar pattern of resistant genes. The dominant phylogenetic group was B2, which was found in 54.0% of the ESC samples and 69.7% of the EUC samples, respectively. The virulence genes of E. coli, which isolated from stones and urine in the same patients, were highly homologous and largely consistent. Meanwhile, these E. coli strains were located in the same clade originated from a common ancestor. ESC and EUC isolated from patients with CaOx stones had a high prevalence of phylogenetic groups B2. Bacterial strains isolated from urine and stones in the same patient had consistent antimicrobial susceptibility profiles, genotyping, phylogenetic groups, virulence and resistance genes, also with high sequence co-linearity and close relationships.

Dissemination of IncF group F1:A2:B20 plasmid-harbouring multidrug-resistant Escherichia coli ST131 before the acquisition of blaCTX-M in Japan

OBJECTIVES

The Escherichia coli O25-ST131 clone is responsible for global dissemination of the bla_CTX-M gene. However, the prevalence of this clone in the digestive tract, devoid of antimicrobial selection, and its molecular epidemiology remain unclear. In this study, we examined the origin of bla_CTX-M-positive E. coli O25-ST131 and its distribution.

METHODS

We separately sequenced the chromosomal and plasmid genomes of 50 E. coli O25 isolates obtained from faecal samples of patients with diarrhoea in Japan.

RESULTS

Although 36 (72%) of 50 E. coli O25 isolates were ST131, only 6 harboured bla_CTX-M. According to the fimH and ybbW sequences and fluoroquinolone susceptibility, H30R1 isolates were dominant (27/36; 75%) and possessed IncFII-FIA-FIB with FAB formula subtype F1:A2:B20 plasmids at a high frequency (24/27; 89%). The F1:A2:B20 plasmids possessed more resistance genes such as bla_TEM-1, aminoglycoside resistance genes and trimethoprim/sulfamethoxazole resistance genes compared with non-F1:A2:B20 plasmids. In contrast, only one bla_CTX-M-14 gene was located on the F1:A2:B20 plasmids, whereas the other three were located on IncFII (F4:A-:B-) (n = 1) and IncZ (n = 2) plasmids. Two H30Rx-ST131 isolates harboured bla_CTX-M-15: one was on the chromosome and the other on the IncFIA-R plasmid. The stability and conjugation ability of the F1:A2:B20 plasmids were compared with those of non-F1:A2:B20 plasmids, which revealed higher stability but lower conjugative ability.

CONCLUSIONS

These results suggest that E. coli H30R1-ST131 is a multidrug-resistant clone containing several resistance genes in the F1:A2:B20 plasmid, which were widely distributed before the acquisition of bla_CTX-M.

National Surveillance of Antimicrobial Susceptibility of Bacteremic Gram-Negative Bacteria with Emphasis on Community-Acquired Resistant Isolates: Report from the 2019 Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART)

A multicenter collection of bacteremic isolates of Escherichia coli (n = 423), Klebsiella pneumoniae (n = 372), Pseudomonas aeruginosa (n = 300), and Acinetobacter baumannii complex (n = 199) was analyzed for susceptibility. Xpert Carba-R assay and sequencing for mcr genes were performed for carbapenem- or colistin-resistant isolates. Nineteen (67.8%) carbapenem-resistant K. pneumoniae (n = 28) and one (20%) carbapenem-resistant E. coli (n = 5) isolate harbored bla _KPC (n = 17), bla _OXA-48 (n = 2), and bla _VIM (n = 1) genes.

Molecular epidemiology of antimicrobial resistant microorganisms in the 21th century: a review of the literature

Healthcare-associated infections (HAIs) are the most frequent and severe complication acquired in healthcare settings with high impact in terms of morbidity, mortality and costs. Many bacteria could be implicated in these infections, but, expecially multidrug resistance bacteria could play an important role. Many microbial typing technologies have been developed until to the the bacterial whole-genome sequencing and the choice of a molecular typing method therefore will depend on the skill level and resources of the laboratory and the aim and scale of the investigation. In several studies the molecular investigation of pathogens involved in HAIs was performed with many microorganisms identified as causative agents such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Clostridium difficile, Acinetobacter spp., Enterobacter spp., Enterococcus spp., Staphylococcus aureus and several more minor species. Here, we will describe the most and least frequently reported clonal complex, sequence types and ribotypes with their worldwide geographic distribution for the most important species involved in HAIs.

Clinically Relevant Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates From Food Animals in South Korea

Extended-spectrum β-lactam antimicrobials have been broadly used in food animals and humans to control infectious diseases. However, the emergence and rapid spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, mainly Escherichia coli, have seriously threatened global health in recent decades. In this study, we determined the prevalence, antimicrobial susceptibility, and genetic properties of ESBL-producing E. coli (ESBL-EC) strains isolated from food animals in South Korea. A total of 150 fecal samples from healthy chickens (n = 34), pigs (n = 59), and cattle (n = 57) were screened from January to July 2018. Among these, 77 non-duplicate cefotaxime-resistant ESBL-EC strains were isolated from 32 chicken, 41 pig, and 4 cattle samples, with the corresponding occurrence rates of 94.1, 69.5, and 7.0%, respectively. All the isolates showed multidrug resistance (MDR) and produced at least one type of β-lactamase, including CTX-M (98.7%) and TEM (40.3%). CTX-M-14 (53.1%), CTX-M-55 (53.7%), and CTX-M-65 (50.0%) were the predominant genotypes in the chicken, pig, and cattle samples, respectively. Multilocus sequence typing revealed 46 different sequence types (STs), including the human-associated extraintestinal pathogenic E. coli ST131 (n = 2), ST10 (n = 5), ST38 (n = 1), ST410 (n = 4), ST354 (n = 2), ST58 (n = 3), ST117 (n = 1), and ST457 (n = 1). To the best of our knowledge, this is the first report of pandemic E. coli ST131 in non-human isolates in South Korea. Our results demonstrate the high prevalence and diversity of MDR-ESBL-EC in food animals and highlight them as potential pathogenic ESBL-EC reservoirs that may pose a high risk to human health.

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Clinical Prediction Score for Community-Onset Bloodstream Infections Caused by Extended-Spectrum Beta-Lactamase-Producing Escherichia coli and Klebsiella Species

BACKGROUND

This study aimed to identify the predictors and build a prediction score for community-onset bloodstream infections (CO-BSIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella species.

METHODS

All CO-BSIs caused by E. coli and Klebsiella species from 2012 to 2015 were grouped into derivation (BSIs from 2012 to 2014) and validation (BSIs in 2015) cohorts. A prediction score was built using the coefficients of the multivariate logistic regression model from the derivation cohort.

RESULTS

The study included 886 CO-BSIs (594 and 292 in the derivation and validation cohorts, respectively). The independent predictors of CO-BSIs caused by ESBL-producing E. coli and Klebsiella species included: 1) identification of ESBL-producing microorganisms from any clinical culture within one year of admission, 2) beta-lactam or fluoroquinolone treatment within 30 days (with 2 or more courses within 90 days; with 1 course within 90 days), 3) hospitalization within one year, 4) the presence of an indwelling urinary catheter at the time of admission. The area under the curve (AUC) of the clinical prediction score was 0.72 (95% confidence interval [CI], 0.68-0.77). In the validation cohort, the AUC was 0.70 (95% CI, 0.63-0.77).

CONCLUSIONS

The results of this study suggest a simple and easy-to-use scoring system to predict CO-BSIs caused by ESBL-producing E. coli and Klebsiella species.

The role of wildlife (wild birds) in the global transmission of antimicrobial resistance genes

Antimicrobial resistance is an urgent global health challenge in human and veterinary medicine. Wild animals are not directly exposed to clinically relevant antibiotics; however, antibacterial resistance in wild animals has been increasingly reported worldwide in parallel to the situation in human and veterinary medicine. This underlies the complexity of bacterial resistance in wild animals and the possible interspecies transmission between humans, domestic animals, the environment, and wildlife. This review summarizes the current data on expanded-spectrum β-lactamase (ESBL), AmpC β-lactamase, carbapenemase, and colistin resistance genes in Enterobacteriaceae isolates of wildlife origin. The aim of this review is to better understand the important role of wild animals as reservoirs and vectors in the global dissemination of crucial clinical antibacterial resistance. In this regard, continued surveillance is urgently needed worldwide.

Trends in South Korean antimicrobial use and association with changes in Escherichia coli resistance rates: 12-year ecological study using a nationwide surveillance and antimicrobial prescription database

The purpose of this study is to determine the correlation between use of antimicrobials, such as fluoroquinolone, cefoxitin, and cefotaxime, and Escherichia coli resistance using a nationwide database. Nationwide data on antimicrobial consumption for 12 years (2002 to 2013) were acquired from a database of subjects (n = 1,025,340) included in the National Health Insurance Service-National Sample Cohort. National antimicrobial resistance rates of E. coli were obtained from the Korean Antimicrobial Resistance Monitoring System, which has been administered by the Korean Centers for Disease Control and Prevention since 2002. Fluoroquinolone-resistance rates of E. coli isolated from general hospitals have continuously increased since 2002 and were correlated with nationwide fluoroquinolone use (r = 0.82, P = 0.0012) or ciprofloxacin use (r = 0.90, P<0.0001). Cefotaxime-resistance rates of E. coli isolated from general hospitals markedly increased since 2008 and were correlated with nationwide cefotaxime use (r = 0.94, P<0.0001) or third-generation cephalosporin use (r = 0.96, P<0.0001). Cefoxitin-resistance rates of E. coli isolated from general hospitals peaked in 2010 and significantly correlated with cephamycin use at a two-year interval (r = 0.64, P = 0.0256). In conclusion, consumption of antimicrobials such as fluoroquinolone, cefoxitin, and cefotaxime is well correlated with the resistance rates of E. coli to these agents. This study provides background data for national antimicrobial management policies to reduce antimicrobial resistance.

Descriptive Epidemiology of Acute Pyelonephritis in Korea, 2010-2014: Population-based Study

BACKGROUND

Acute pyelonephritis (APN) is one of the most common community-acquired bacterial infections. Recent increases of antimicrobial resistance in urinary pathogens might have changed the other epidemiologic characteristics of APN. The objective of this study was to describe the current epidemiology of APN in Korea, using the entire population.

METHODS

From the claims database of the Health Insurance Review and Assessment Service in Korea, the patients with International Classification of Diseases, 10th Revision codes N10 (acute tubulo-interstitial nephritis) or N12 (tubulo-interstitial nephritis, neither acute nor chronic) as the primary discharge diagnosis during 2010-2014 were analyzed, with two or more claims during a 14-day period considered as a single episode.

RESULTS

The annual incidence rate of APN per 10,000 persons was 39.1 and was on the increase year to year (35.6 in 2010; 36.7 in 2011; 38.9 in 2012; 40.1 in 2013; 43.8 in 2014, P = 0.004). The increasing trend was observed in both inpatients (P = 0.014) and outpatients (P = 0.004); in both men (P = 0.042) and women (P = 0.003); and those aged under 55 years (P = 0.014) and 55 years or higher (P = 0.003). Eleven times more women were diagnosed and treated with APN than men (men vs. women, 6.5 vs. 71.3), and one of every 4.1 patients was hospitalized (inpatients vs. outpatients, 9.6 vs. 29.4). The recurrence rate was 15.8%, and the median duration from a sporadic episode (i.e., no episode in the preceding 12 months) to the first recurrence was 44 days. The recurrence probability increased with the number of previous recurrences. The average medical cost per inpatient episode was USD 1,144, which was 12.9 times higher than that per outpatient episode (USD 89).

CONCLUSION

The epidemiology of APN in Korea has been changing with an increasing incidence rate.

Clinical and Molecular Correlates of Escherichia coli Bloodstream Infection from Two Geographically Diverse Centers in Rochester, Minnesota, and Singapore

Escherichia coli bacteremia is caused mainly by sequence type complex 131 (STc131) and two clades within its fluoroquinolone-resistance-associated H30 subclone, H30R1 and H30Rx. We examined clinical and molecular correlates of E. coli bacteremia in two geographically distinct centers. We retrospectively studied 251 unique E. coli bloodstream isolates from 246 patients (48 from the Mayo Clinic, Rochester, MN [MN], and 198 from Tan Tock Seng Hospital, Singapore [SG]), from October 2013 through March 2014. Isolates underwent PCR for phylogroup, STc, bla_CTX-M type, and virulence gene profiles, and medical records were reviewed. Although STc131 accounted for 25 to 27% of all E. coli bacteremia isolates at each site, its extended-spectrum-β-lactamase (ESBL)-associated H30Rx clade was more prominent in SG than in MN (15% versus 4%; P = 0.04). In SG only, patients with STc131 (versus other E. coli STc isolates) were more likely to receive inactive initial antibiotics (odds ratio, 2.8; P = 0.005); this was true specifically for patients with H30Rx (odds ratio, 7.0; P = 0.005). H30Rx comprised 16% of community-onset bacteremia episodes in SG but none in MN. In SG, virulence scores were higher for H30Rx than for H30R1, non-H30 STc131, and non-STc131 isolates (P < 0.02 for all comparisons). At neither site did mortality differ by clonal status. The ESBL-associated H30Rx clade was more prevalent and more often of community onset in SG, where it predicted inactive empirical treatment. The clonal distribution varies geographically and has potentially important clinical implications. Rapid susceptibility testing and clonal diagnostics for H30/H30Rx might facilitate earlier prescribing of active therapy.

Risk factors and molecular features of sequence type (ST) 131 extended-Spectrum-β-lactamase-producing Escherichia coli in community-onset female genital tract infections

BACKGROUND

Escherichia coli (E. coli) is known to cause urinary tract infection (UTI) and meningitis in neonates, as well as existing as a commensal flora of the human gut. Extended-spectrum β-lactamase (ESBL)-producing E. coli has increased in the community with the spread of CTX-M type ESBL-producing sequence type 131 (ST131)-O25-H30Rx E. coli clone. The role of ESBL-producing E. coli in female genital tract infection has not been elucidated. The clinical and molecular features of E. coli isolated from community-onset female genital tract infections were evaluated to elucidate the current burden in the community, focusing on the highly virulent and multidrug-resistant ST131 clone.

METHODS

We collected and sequenced 91 non-duplicated E. coli isolates from the female genital tract of 514 patients with community-onset vaginitis. ESBL genotypes were identified by PCR and confirmed to be ESBL-producers by sequencing methods. ST131 clones were screened by PCR for O16-ST131 and O25b-ST131. Pulsed-field gel electrophoresis (PFGE) and PCR-based replicon typing (PBRT) were conducted in ESBL producers. Independent clinical risk factors associated with acquiring ESBL-producing E. coli and ST131 clone were analyzed using multivariate logistic regression analysis.

RESULTS

Of the 514 consecutive specimens obtained from the infected female genital tract, 17.7% (91/514) had E. coli infection, of which 19.8% (18/91) were ESBL producers. CTX-M-15 was the most common type (n = 15). O25b-ST131 and O16-ST131 clones accounted for 15.4% (14/91) and 6.6% (6/91), respectively. In plasmid analysis, ten isolates succeeded in conjugation and plasmid types were IncFII (n = 4), IncFI (n = 3), IncI1-Iγ (n = 3) with one non-typable case. Compared to ESBL-nonproducing E. coli, ESBL-producing E. coli acquisition was strongly associated with recurrent vaginitis (OR 40.130; 95% CI 9.980-161.366), UTI (OR 18.915; 95% CI 5.469-65.411), and antibiotics treatment (OR 68.390; 95% CI 14.870-314.531).

CONCLUSION

A dominant clone of CTX-M type ESBL-producing E. coli in conjugative plasmids seems to be circulating in the community and considerable number of ST131 E. coli in the genital tract of Korean women was noted. Sustained monitoring of molecular epidemiology and control of the high-risk group is needed to prevent ESBL-producing E. coli from spreading throughout the community.

Epidemiology and treatment of antimicrobialresistant gram-negative bacteria in Korea

Antimicrobial resistance is becoming one of the greatest challenges to public health worldwide. Infections by antimicrobial-resistant organisms could result in the failure of treatment, increased medical costs, prolonged hospital stays, and an increased socioeconomic burden. Antimicrobial usage in Korea remains heavy, even after much effort to reduce their use. According to the Korean antimicrobial resistance surveillance system, the resistance rates of many bacteria are increasing. The resistance rate of Acinetobacter baumannii to imipenem in Korea increased to 85% in 2015, representing a major public threat. The reports of increased carbapenem resistance in Enterobacteriaceae are worrisome. More importantly, some carbapenem-resistant Enterobacteriaceae may result from the production of carbapenemases, which break down carbapenems. There are relatively few treatment options for extensively drug-resistant A. baumannii and carbapenem-resistant Enterobacteriaceae. Most reports are retrospective observational studies. Because there are little published data from randomized controlled trials, more data assessing antimicrobial treatment for extensively drug-resistant A. baumannii and carbapenem-resistant Enterobacteriaceae are needed to make treatment recommendations.

Extended-spectrum β-lactamase-producing Escherichia coli bacteremia: Comparison of pediatric and adult populations

BACKGROUND/PURPOSE

The prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing worldwide. This study investigated the clinical features and bacteriology of pediatric patients with ESBL-producing E. coli bacteremia and compared their characteristics with those of adult patients.

METHODS

Clinical and laboratory data from all of the 41 patients aged ≤18 years diagnosed with E. coli bacteremia were collected over 5 years. Patients aged >18 years diagnosed with E. coli bacteremia, matched 1:1 for calendar time, were enrolled as the adult group. All E. coli isolates were tested for their blaCTX-M group and sequence type 131 (ST131). A novel seven-single nucleotide polymorphism-based clonotyping test was applied to detect the septatypes of each isolate.

RESULTS

In the adult group, patients with ESBL-producing E. coli bacteremia had more previous hospitalizations and antimicrobial agent use than did those with non-ESBL-producing E. coli bacteremia, but these differences were not found in pediatric group. In the pediatric group, the proportion of isolates producing CTX-M group 9 was higher than that in the adult group (85.7% vs. 42.9%; p < 0.05). Among both groups, there were more E. coli ST131 in ESBL isolates in than there were non-ESBL isolates. The distribution of septatypes was more homogenous in ESBL-producing E. coli among the pediatric patients than among the adult patients.

CONCLUSION

ST131 was the major clone causing E. coli bacteremia in both pediatric and adult populations. The pediatric population demonstrated a higher number of isolates producing CTX-M group 9 with more homogenous septatypes compared with the adult population.