Prevalence of rectal carriage of extended-spectrum β-lactamase-producingEscherichia coliamong elderly people in community settings in China

Extended-Spectrum Beta-Lactamase- and Plasmidic AmpC-Producing Enterobacterales among the Faecal Samples in the Bulgarian Community

The aim of the present work was to genetically characterise cefotaxime-resistant enterobacteria isolated from community carriers in Bulgaria. In total, 717 faecal samples from children and adults in five medical centres in Sofia, Pleven and Burgas were examined. Antimicrobial susceptibility was evaluated by the disk diffusion method. blaESBL or plasmidic AmpC (pAmpC) genes were detected by PCR and sequencing. MLST and ERIC-PCR were used to detect clonal relatedness. Among the faecal samples, 140 cefotaxime-resistant enterobacteria were found. The most frequently detected species was Escherichia coli (77.9%, 109/140 samples), followed by Klebsiella pneumoniae (7.9%, 11/140). Among the isolates, blaCTX-M-15 (37.1%) was predominant, followed by blaCTX-M-3 (19.2%), blaCTX-M-14 (10%), and blaCTX-M-27 (4.3 %). Genes encoding pAmpC were observed in 11.4% (blaDHA-1, 16/140) and in 1.4% (blaCMY-2, 2/140). The frequency of ESBL and pAmpC producers among the subjects was 14.6% and 2.5%, respectively. No carbapenem-resistant isolates were found. Four main clonal complexes (CC131, CC10, CC38, and CC155) were detected among E. coli isolates. The most common type was ST131, phylogroup B2 (16.5%). The increased frequency of ESBL- and pAmpC-producing enterobacteria in the community is a prerequisite for treatment failures of the associated infections and a good background for further studies.

Extended spectrum beta-lactamase carriage among elderly residents of a long-term care facility in Beirut

BACKGROUND

Antimicrobial resistance is an emerging problem worldwide, endangering antimicrobials efficacy and resulting in high rates of morbidity and mortality. It is one of the major concerns that health care facilities are facing nowadays. Mainly, extended-spectrum beta-lactamases (ESBL)-producing Enterobacterales play a role in hydrolyzing β-lactams, specifically the third-generation cephalosporins. This study aimed to investigate the prevalence of fecal carriage and molecular characterization of ESBL-producing Enterobacterales among Lebanese elderly residents in a long-term care facility (Dar Al-Ajaza Al Islamia Hospital).

METHODS

Rectal culture swab specimens were collected from 132 patients at Dar Al Ajaza Al Islamia hospital between January 2019 till June 2020. The phenotype of ESBL producers was confirmed by a modified double disc synergy test and antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. Genotypically, multiplex polymerase chain reaction was used to detect the ESBL genes.

RESULTS

The main Enterobacterales strain observed was E coli (90.15%) followed by Klebsiella pneumoniae (4.54%) and Klebsiella oxytoca (3.80%). It has been found that the ESBL percentage rate has decreased when compared to a study conducted previously at the same hospital. Moreover, the predominant ESBL gene was CTX-M (cefotaximase).

CONCLUSIONS

This study is the first to demonstrate the improved current status of ESBL in one long-term care facility. In addition, the CTX-M is still the major type in ESBL-producing organisms.

High level of colonization with 3rd-generation cephalosporin-resistant Enterobacterales in African community settings, Ghana

A cross-sectional survey was conducted in eight Ghanaian communities to investigate the extent of intestinal colonization with 3^rd-generation cephalosporin-resistant Enterobacterales. The study collected faecal samples and corresponding lifestyle data from 736 healthy residents to assess the occurrence of cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae, with a focus on genotypes of plasmid-mediated ESBLs, AmpCs, and carbapenemases. The results showed that 371 participants (50.4%) carried 3^rd-generation cephalosporin-resistant E. coli (n=362) and K. pneumoniae (n=9). Most of these were ESBL-producing E. coli (n=352, 94.9%), carrying CTX-M genes (96.0%, n=338/352), mostly for CTX-M-15 (98.9%, n=334/338). Nine participants (1.2%) carried AmpC-producing E. coli that harboured bla_DHA-1 or blaCMY-2 genes, and two participants (0.3%) each carried a carbapenem-resistant E. coli that harboured both bla_NDM-1 and bla_CMY-2. Quinolone-resistant O25b: ST131 E. coli were recovered from six participants (0.8%) and were all CTX-M-15 ESBL-producers. Having a household toilet facility was significantly associated with a reduced risk of intestinal colonization (adjusted odds ratio, 0.71; 95% CI, 0.48-0.99; P-value=0.0095) in multivariate analysis. These findings raise serious public health concerns, and effective control of the spread of antibiotic-resistant bacteria is possible by providing better sanitary conditions for communities.

OUP accepted manuscript

Objectives

The widespread intestinal carriage of ESBL-producing Escherichia coli (ESBL E. coli) among both patients and healthy individuals is alarming. However, the global prevalence and trend of this MDR bacterium in healthcare settings remains undetermined. To address this knowledge gap, we performed a comparative meta-analysis of the prevalence in community and healthcare settings.

Methods

Our systematic review included 133 articles published between 1 January 2000 and 22 April 2021 and indexed in PubMed, EMBASE or Google Scholar. A random-effects meta-analysis was performed to obtain the global pooled prevalence (community and healthcare settings). Subgroup meta-analyses were performed by grouping studies using the WHO regions and 5 year intervals of the study period.

Results

We found that 21.1% (95% CI, 19.1%–23.2%) of inpatients in healthcare settings and 17.6% (95% CI, 15.3%–19.8%) of healthy individuals worldwide carried ESBL E. coli in their intestine. The global carriage rate in healthcare settings increased 3-fold from 7% (95% CI, 3.7%–10.3%) in 2001–05 to 25.7% (95% CI, 19.5%–32.0%) in 2016–20, whereas in community settings it increased 10-fold from 2.6% (95% CI, 1.2%–4.0%) to 26.4% (95% CI, 17.0%–35.9%) over the same period.

Conclusions

The global and regional human intestinal ESBL E. coli carriage is increasing in both community and healthcare settings. Carriage rates were generally higher in healthcare than in community settings. Key relevant health organizations should perform surveillance and implement preventive measures to address the spread of ESBL E. coli in both settings.

The global prevalence and trend of human intestinal carriage of ESBL-producing Escherichia coli in the community

OBJECTIVES

Intestinal colonization by ESBL Escherichia coli and its association with community-acquired MDR infections is of great concern. This review determined the worldwide prevalence of human faecal ESBL E. coli carriage and its trend in the community over the past two decades.

METHODS

A systematic literature search was conducted using PubMed, EMBASE and Google Scholar to retrieve articles published between 1 January 2000 and 13 February 2020 that contained data on the prevalence of faecal carriage of ESBL E. coli among healthy individuals. A cumulative (for the whole period) meta-analysis was used to estimate the global and regional pooled prevalence rates. Articles were grouped into study periods of 3 years, and subgroup meta-analyses were undertaken to examine the global pooled prevalence over time.

RESULTS

Sixty-two articles covering 29 872 healthy persons were included in this meta-analysis. The cumulative (2003-18) global pooled prevalence of ESBL E. coli intestinal carriage in the community was 16.5% (95% CI 14.3%-18.7%; P  <  0.001). The pooled prevalence showed an upward trend, increasing from 2.6% (95% CI 1.6%-4.0%) in 2003-05 to 21.1% (95% CI 15.8%-27.0%) in 2015-18. Over the whole period, the highest carriage rate was observed in South-East Asia (27%; 95% CI 2.9%-51.3%), while the lowest occurred in Europe (6.0%; 95% CI 4.6%-7.5%).

CONCLUSIONS

Globally, an 8-fold increase in the intestinal carriage rate of ESBL E. coli in the community has occurred over the past two decades. Prevention of its spread may require new therapeutic and public health strategies.

Selection of ESBL-Producing E. coli in a Mouse Intestinal Colonization Model

Asymptomatic human carriage of antimicrobially drug-resistant pathogens prior to infection is increasing worldwide. Further investigation into the role of this fecal reservoir is important for combatting the increasing antimicrobial resistance problems. Additionally, the damage on the intestinal microflora due to antimicrobial treatment is still not fully understood. Animal models are powerful tools to investigate bacterial colonization subsequent to antibiotic treatment. In this chapter we present a mouse-intestinal colonization model designed to investigate how antibiotics select for an ESBL-producing E. coli isolate. The model can be used to study how antibiotics with varying effect on the intestinal flora promote the establishment of the multidrug-resistant E. coli. Colonization is successfully investigated by sampling and culturing stool during the days following administration of antibiotics. Following culturing, a precise identification of the bacterial strain found in mice feces is applied to ensure that the isolate found is in fact identical to the strain used for inoculation. For this purpose random amplified of polymorphic DNA (RAPD) PCR specifically developed for E. coli is applied. This method allows us to distinguish E. coli with more than 99.95% genome similarity using a duplex PCR method.

To check or not to check. Rectal ESBL colonization in hospitalized elderly patients

BACKGROUND

The worldwide spread of extended-spectrum-beta-lactamase (ESBL) producing bacteria has affected health care. ESBL confers resistance to the majority of beta-lactam antibiotics.

MATERIALS AND METHODS

We intended to quantify the rates of rectal ESBL-positive and negative patients that eventually developed fever and urinary tract infection (UTI). All rectal ESBL-positive patients were to be initially treated with the conventional antibiotics that have anti-ESBL activity (amikacin or ertapenem), while ESBL-negative patients were given ceftriaxone.

RESULTS

Most patients were rectal ESBL-positive (60.7%). Fever was in 51% patients; 67.8% of them developed signs and symptoms of UTI. Most patients with UTI were urinary ESBL-positive (79%), most rectal ESBL-negative patients were urinary ESBL-negative (75%), (χ² = 18.5, df = 1, P < .001). Overall mortality was higher in the febrile group (39, 34.8%) versus the afebrile (1, 0.9%) (χ² = 42, df = 1, P < .001). The mortality rate in the febrile group was significantly higher in the rectal ESBL-positive patients (χ2 = 7.5, df = 1, P = .006).

DISCUSSION

The direct correlation of rectal ESBL-positive and negative and respectively urinary ESBL-positive and negative patients' advocate for the use of antibiotics with anti-ESBL activity as an empiric treatment of rectal ESBL-positive patients with suspected UTI.

CONCLUSION

In our opinion, it is worthwhile to identify rectal ESBL-positivity on hospital admission.

Extended-spectrum β-lactamase-producing Escherichia coli contributes to the survival of cefotaxime-susceptible E. coli under high concentrations of cefotaxime by acquisition of increased AmpC expression

Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-E) are becoming increasingly widespread in Vietnam. Antibiotics are detected in many Vietnamese foods; however, the effect of ESBL-E and antibiotic consumption on intestinal bacteria has not been studied sufficiently. Here, we investigated the effect of oral administration of ESBL-E (TB19) and cefotaxime on luminescence-emitting cefotaxime-sensitive E. coli (X14). Mice were given water containing TB19 and then received three injections of 1.0 × 108 CFU of X14 harboring a luciferase gene. The mice were administered 100 μg of cefotaxime and luminescent bacteria were monitored over 24 h, following which luminescent bacteria were isolated from mouse feces. Luminescence continued to be detected in mice administered TB19 24 h after cefotaxime ingestion. Fecal analysis revealed two types of luminescent colonies: cefoxitin-resistant E. coli (X14-R) and Pseudomonas aeruginosa. Pulse-field gel electrophoresis confirmed that X14-R was a clonal strain of X14, suggesting that X14 survived using ESBLs originating from TB19 and acquired cefoxitin resistance due to cefotaxime consumption. Moreover, in vitro analysis of X14 indicated that expression of the ampC gene was upregulated by cefotaxime. Overall, ESBL-E and cefotaxime promoted the expansion of cefoxitin-resistant E. coli in the absence of plasmid-mediated gene transfer.

Prevalence of antimicrobial resistant Escherichia coli from patients with suspected urinary tract infection in primary care, Denmark

BACKGROUND

Escherichia coli is the most common pathogen causing Urinary Tract Infections (UTI). Data from the current National Surveillance program in Denmark (DANMAP) may not accurately represent the prevalence of resistant E. coli in primary care, because only urine samples from complicated cases may be forwarded to the microbiological departments at hospitals for diagnostic examination. The aim of this study was to assess the prevalence of resistant E. coli to the most commonly used antimicrobial agents in primary care in a consecutive sample of patients from general practice.

METHODS

Observational study carried out from December 2014 to December 2015. Thirty-nine general practices from The Capital Region of Denmark included adult patients with urinary tract symptoms and suspected UTI. All urine samples were sent to the central laboratory Statens Serum Institut (SSI). Significant bacteriuria was interpreted according to the European Urinalysis Standards. Susceptibility testing was performed and interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) standards.

RESULTS

From the 39 general practices 505 patients were recruited. Completed data were obtained from 485 (96%) patients. According to the European Urinalysis Standards, 261 (54%) patients had positive bacteriuria. The most common uropathogen in patients with uncomplicated (uUTI) and complicated (cUTI) urinary tract infection was E. coli 105 (69%) and 76 (70%), respectively. Eighty-two (45%) of 181 E. coli isolates were resistant to at least one of the tested antibiotics and 50 out of 82 isolates were resistant to two or more antimicrobial agents. The highest resistance-rate was found against ampicillin 34% (95% CI 24;42) in uUTI and 36% (24;46) in cUTI. There were no differences in the distribution of resistance between uncomplicated and complicated cases. The prevalence of resistance was similar to the one reported in DANMAP 2014.

CONCLUSION

In E. coli from uUTI there is high resistance rates to antimicrobial agents commonly used in primary care. There was no difference in the distribution of resistant E. coli in suspected uUTI vs cUTI. In Denmark, data from the National Surveillance program DANMAP can guide the decision for choice of antibiotic in patients with suspected UTI seeking care in primary care.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02249273 .

Comparison of rates of fecal colonization with extended-spectrum beta-lactamase-producing enterobacteria among patients in different wards, outpatients and medical students

Because asymptomatic carriage of extended-spectrum beta-lactamase (ESBL) producers is a risk factor for infection, data on colonization dynamics are important when planning infection control. This study investigated fecal colonization with ESBL producers among inpatients, outpatients and medical students and compares the characteristics of ESBL producers among these groups. Carriage rates were investigated in 5581 fecal samples; 4343 from inpatients (330, 1397, 619 and 1864 from adult ICUs [intensive care units], adult non-ICUs, pediatric ICUs and pediatric non-ICUs, respectively), 814 from outpatients and 424 from screening of medical students. ESBL producers were characterized by co-resistance, integrons carried, and aminoglycoside resistance and ESBL genes. Dynamic regression models were built to identify relationships between combinations of time series of monthly antibiotic consumption, prevalence of carriers and infected subjects. Inpatients, ICU patients and adults showed higher prevalence than outpatients, non-ICU patients or children (7.4%, 9.3% and 12.0% vs. 3.1%, 6.1% and 4.1%, respectively). Klebsiella pneumoniae was more frequent in ICU patients; dominance of CTX-M-15 producers was more marked in adult than in pediatric inpatients. ESBL carriage was shown to be a consequence of infection in adults in the time-series analysis; antibiotic consumption had little effect. The epidemiology of colonization with ESBL producers differed between pediatric ICU, adult ICU and adult non-ICU patients. In adults, carriage of ESBL producers seems to be the consequence of infection, especially in ICU patients; the main source of colonization is nosocomial acquisition. In contrast, children are less likely to acquire colonizer strains in hospitals; importation of ESBL producers by colonized children seems to be significant.

Fecal carriage of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella spp. in a Turkish community

BACKGROUND/AIM

The aim of this study was to determine the prevalence of fecal carriage of extended-spectrum beta-lactamase (ESBL)-producing bacteria, enzyme types, and risk factors affecting colonization.

MATERIALS AND METHODS

A total of 576 stool samples from outpatients were examined between October 2012 and May 2013. Screening was done with selective EMB plates. ESBL were detected by double-disk synergy and confirmed agar strip gradient methods. Enzyme types were determined by PCR.

RESULTS

The prevalence of fecal carriage was found as 30% (173 of 576). Recent use of antibiotics, hospitalization and surgical operation, diabetes, crowded household populations, and old age were associated with higher carriage rates. Of the ESBL-producing bacteria, 87.5% were positive for bla_CTX-M genes. Of the bla_CTX-M gene-positive isolates, 95.2% were positive for bla_CTX-M-1 genes; among these, 82.2% were positive for bla_CTX-M-3 and 67.7% were positive for bla_CTX-M-15 genes while 62.5% isolates were positive for both bla_CTX-M-3 and bla_CTX-M-15 genes Conclusions: A high rate (30%) of fecal carriage of ESBL bacteria was found in an adult population. The predominant beta-lactamase enzyme types were CTX-M-3 and CTX-M-15.

Comparison of antibiotic resistant Escherichia coli obtained from drinking water sources in northern Tanzania: a cross-sectional study

Background

Antimicrobial resistance (AMR) is a growing and significant threat to public health on a global scale. Escherichia coli comprises Gram-negative, fecal-borne pathogenic and commensal bacteria that are frequently associated with antibiotic resistance. AMR E. coli can be ingested via food, water and direct contact with fecal contamination.

Methods

We estimated the prevalence of AMR Escherichia coli from select drinking water sources in northern Tanzania. Water samples (n = 155) were collected and plated onto Hi-Crome E. coli and MacConkey agar. Presumptive E. coli were confirmed by using a uidA PCR assay. Antibiotic susceptibility breakpoint assays were used to determine the resistance patterns of each isolate for 10 antibiotics. Isolates were also characterized by select PCR genotyping and macro-restriction digest assays.

Results

E. coli was isolated from 71 % of the water samples, and of the 1819 E. coli tested, 46.9 % were resistant to one or more antibiotics. Resistance to ampicillin, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim was significantly higher (15–30 %) compared to other tested antibiotics (0–6 %; P < 0.05). Of the β-lactam-resistant isolates, bla_TEM-1 was predominant (67 %) followed by bla_CTX-M (17.7 %) and bla_SHV-1 (6.0 %). Among the tetracycline-resistant isolates, tet(A) was predominant (57.4 %) followed by tet(B) (24.0 %). E. coli isolates obtained from these water sources were genetically diverse with few matching macro-restriction digest patterns.

Conclusion

Water supplies in northern Tanzania may be a source of AMR E. coli for people and animals. Further studies are needed to identify the source of these contaminants and devise effective intervention strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0870-9) contains supplementary material, which is available to authorized users.

Fecal Carriage of Extended-Spectrum β-Lactamases in Healthy Humans, Poultry, and Wild Birds in León, Nicaragua-A Shared Pool of blaCTX-M Genes and Possible Interspecies Clonal Spread of Extended-Spectrum β-Lactamases-Producing Escherichia coli

Antibiotic-resistant bacteria are a major concern in the healthcare of today, especially the increasing number of gram-negative bacteria producing β-lactamases such as extended-spectrum β-lactamases (ESBLs). However, little is known about the relationship of ESBL producers in humans and domestic and wild birds, especially in a low-income setting. Therefore, we studied the fecal carriage of ESBL-producing Escherichia coli and Klebsiella pneumoniae in healthy humans, poultry, and wild birds in the vicinity of León, Nicaragua. Three hundred fecal samples were collected during December 2012 from humans (n = 100), poultry (n = 100) and wild birds (n = 100). The samples were examined for ESBL-producing E. coli and K. pneumoniae, revealing the prevalence of 27% in humans, 13% in poultry, and 8% in wild birds. Further characterization of the ESBL-producing isolates was performed through polymerase chain reaction (PCR) (NDM, CTX-M), epidemiological typing (ERIC2-PCR), multilocus sequence typing, and sequencing. ESBL producers harbored bla_CTX-M-2, bla_CTX-M-15, bla_CTX-M-22, and bla_CTX-M-3 genotypes. The bla_CTX-M-15 constituted the absolute majority of ESBL genes among all samples. ERIC-PCR demonstrated highly related E. coli clones among humans, poultry, and wild birds. Clinically relevant E. coli clone ST648 was found in humans and poultry. There is a shared pool of bla_CTX-M genes between humans and domesticated and wild birds in Nicaragua, and the results suggest shared clones of ESBL-producing E. coli. The study adds to the notion that wild birds and poultry can pick up antibiotic-resistant bacteria of human origin and function as a melting pot of resistance. Structured surveillance programs of antimicrobial resistance and a more regulated prescription of antibiotics are warranted in Nicaragua.

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.

Dissemination of the multidrug-resistant extended-spectrum β-lactamase-producing Escherichia coli O25b-ST131 clone and the role of house crow (Corvus splendens) foraging on hospital waste in Bangladesh

Two hundred and thirty-eight faecal samples from crows foraging on hospital wastes were analysed for extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. ESBL-producing crow isolates were characterized and compared with 31 patient isolates. Among the crows, 59% carried ESBL producers. These included Escherichia coli, Klebsiella pneumoniae, Raoultella terrigena and Enterobacter cloacae harbouring the genes for CTX-M-1, CTX-M-15, CTX-M-55, CTX-M-79, and CTX-M-14. Human isolates carried only the CTX-M-15 gene. Two-thirds of crow E. coli isolates and all human E. coli isolates were multidrug resistant. Crows and patients shared E. coli sequence types, including the epidemic E. coli O25b-ST131 clone. The scavenging behaviour of crows at poorly managed hospital waste dumps made them potential reservoirs of antibiotic resistance, including ESBLs.

Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China

Objectives

The objectives of this study were to determine CTX-M-producing Escherichia coli ST131 strain prevalence in stool specimens from healthy subjects in central China and to molecularly characterize clonal groups.

Methods

From November 2013 to January 2014, stool specimens from healthy individuals in Hunan Province were screened for ESBL-producing E. coli using chromogenic medium and CTX-M genotypes and phylogenetic groups were determined. ST131 clonal groups were detected by PCR and characterized for antibiotic resistance, fimH, gyrA and parC alleles, plasmid-mediated quinolone resistance determinants, virulence genotypes and PFGE patterns.

Results

Among 563 subjects, 287 (51.0%) exhibited the presence of faecal ESBL-producing E. coli, all of which produced CTX-M enzymes. The most common CTX-M genotypes were CTX-M-14 (48.4%), CTX-M-15 (27.5%) and CTX-M-27 (15.0%). Of the 287 CTX-M-producing isolates, 32 (11.1%) belonged to the ST131 clone. O16-ST131 isolates were dominant (75%) and contained the fimH41 allele. The remaining eight (25%) ST131 isolates were of the O25b subgroup and contained fimH30 or fimH41. Ciprofloxacin resistance was found in 100% of the O25b-ST131 isolates, whereas only 8% of the O16-ST131 isolates were resistant. All of the O25b-ST131 isolates except one showed gyrA1AB and parC1aAB mutations; most of the O16-ST131 isolates had gyrA1A and parC1b mutations. The virulence genotypes of O16-ST131 resembled those of the O25b-ST131 isolates. The 32 ST131 isolates formed one large group at the 64% similarity level. They comprised 15 PFGE groups (defined at ≥85% similarity).

Conclusions

O16-ST131 isolates have emerged as the predominant type of ST131 isolate in faecal CTX-M-producing E. coli in healthy individuals in China.

High prevalence and risk factors of fecal carriage of CTX-M type extended-spectrum beta-lactamase-producing Enterobacteriaceae from healthy rural residents of Taian, China

The study was carried out to understand the prevalence of CTX-M type extended-spectrum beta-lactamase (ESBL)-harboring Enterobacteriaceae and to analyze risk factors related with fecal carriage in healthy rural residents in Taian, China. A total of 620 stool samples were collected from rural residents. The ESBL-positive Enterobacteriaceae was screened using ChromID ESBL agar, and then further confirmed by double-disk diffusion. The CTX-M genes were determined using polymerase chain reaction. The risk factors associated with fecal carriage of CTX-M-positive isolates were analyzed using the standard statistic methods. 458 isolates carrying CTX-M gene (458/620, 73.9%) were obtained from different individuals, and the most dominant genotype was CTX-M-9 group (303/458, 66.2%). The dominant species were Escherichia coli (E. coli; 403/458, 88.0%) and Klebsiella pneumoniae (K. pneumoniae; 26/458, 5.7%) among the isolates carrying CTX-M genes. All the CTX-M producers were resistant to ampicillin, cefazolin, cefuroxime, and ceftriaxone, but were all susceptible to biapenem, imipenem, and meropenem. The results of multivariate logistic regression model identified the enrollment in formal education (OR 2.321; 95% CI 1.302–3.768; P= 0.039), the hospitalization history within the last 6 months (OR 1.753; 95% CI 1.127–2.584; P= 0.031) and the antibiotics use within the last 6 months (OR 1.892; 95% CI 1.242–2.903; P= 0.034). The three variables were significantly associated with carriage of CTX-M ESBL producers (x² = 21.21; df = 3; P< 0.001). The prevalence of fecal carriage of CTX-M ESBL-producing Enterobacteriaceae among healthy rural humans in Taian was high, and the recent antibiotic use and hospitalization history may be the important contributors.

Extended spectrum beta-lactamase carriage state among elderly nursing home residents in Beirut

Introduction. ESBL-producing Enterobacteriaceae can cause severe infections, but they are also isolated from the stool of asymptomatic subjects. Faecal carriage of such organism is poorly understood. Methods. First phase of the study was cross-sectional with prevalence and epidemiology of ESBL faecal carriage in two nursing homes in Beirut: 57 residents in the first (NH1) and 151 residents in the second (NH2). In second phase, faecal swabs from cohort of NH1 residents were examined for carriage at six-week intervals over three-month period. Residents' charts were reviewed to assess carriage risk factors. Results. Over 3 consecutive samplings at NH1, 81% of residents were at least one-time carriers with 50% at the first round, 60.4% at the second, and 74.5% at the last one. At NH2, 68.2% of residents were carriers. Constipation (in NH1) and antibiotic intake (in NH2) were significantly associated with higher ESBL faecal carriage while the length of stay at the nursing home (in NH2) was associated with less carriage. Conclusion. Faecal carriage of ESBL-producing Enterobacteriaceae is high among nursing home patients in Beirut. The rate of carriage changes rapidly and significantly over time either with multiple factors playing a possible role like outbreak spreading, antibiotic, and health care system exposure.

High Prevalence of CTX-M Beta-Lactamases in Enterobacteriaceae from Healthy Individuals in Guangzhou, China

This study aimed to determine the prevalence of extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae and to characterize the genetic composition of ESBL determinants among Enterobacteriaceae isolates from healthy people in Guangzhou, China. A total of 200 rectal swab samples were collected from healthy asymptomatic individuals and tested for ESBL production using ChromID ESBL agar. Phenotypic ESBL producers were screened for blaCTX-M, blaTEM, and blaSHV genes using PCR and DNA sequencing. The prevalence of ESBL-producing Enterobacteriaceae among rectal swab samples was 69.5%. All ESBL-producing isolates harbored blaCTX-M genes (n=138) except for one isolate that harbored blaSHV-2a. Eleven CTX-M ESBL genes were detected. The most predominant CTX-M-type genes were blaCTX-M-14 (n=82), followed by blaCTX-M-55 (n=19), blaCTX-M-65 (n=10), and blaCTX-M-27 (n=9). Isolates carrying blaCTX-M-38,-3,-15,-14b,-98,-121 and -123 were also identified. Molecular homology analysis of the selected isolates was performed by phylogenetic grouping and multilocus sequence typing and indicated that the predominant clone belonged to A-CC10. This study showed a high rate of CTX-M-type ESBL genes among Enterobacteriaceae isolates from healthy individuals in China.

Multidrug-resistant Gram-negative bacteria: a product of globalization

Global trade and mobility of people has increased rapidly over the last 20 years. This has had profound consequences for the evolution and the movement of antibiotic resistance genes. There is increasing exposure of populations all around the world to resistant bacteria arising in the emerging economies. Arguably the most important development of the last two decades in the field of antibiotic resistance is the emergence and spread of extended-spectrum β-lactamases (ESBLs) of the CTX-M group. A consequence of the very high rates of ESBL production among Enterobacteriaceae in Asian countries is that there is a substantial use of carbapenem antibiotics, resulting in the emergence of plasmid-mediated resistance to carbapenems. This article reviews the emergence and spread of multidrug-resistant Gram-negative bacteria, focuses on three particular carbapenemases--imipenem carbapenemases, Klebsiella pneumoniae carbapenemase, and New Delhi metallo-β-lactamase--and highlights the importance of control of antibiotic use.

Wide dissemination of extended-spectrum β-lactamase-producing Escherichia coli in community residents in the Indochinese peninsula

Recent studies have reported a widespread distribution of extended-spectrum β-lactamase (ESBL)-producing bacteria, not only in the nosocomial setting, but also in the community; some local communities in Southeast Asia have been reported to show a high prevalence of ESBL-producing bacteria. However, the details regarding the quantitative/qualitative state of ESBL-producing bacterial spread in Southeast Asia are currently unclear. Thus, the aim of this study was to assess the state of ESBL-producing bacterial spread in community residents from the Indochinese peninsula, as a representative region of Southeast Asia. In order to achieve this aim, local community residents in Laos and Vietnam were examined for fecal carriage of ESBL-producing Enterobacteriaceae, and the findings were compared with data from a previous study in Thailand which was conducted in the same manner as this study. Between 47.0%–70.2% of the Laotian and Vietnamese residents carried ESBL-producing CTX-M genotype Enterobacteriaceae. The most common sub-genotypes of CTX-M were CTX-M-1 (33.0%–47.5%) and CTX-M-9 (47.5%–64.1%), and these rates were similar among all three countries. Taken together, these results confirmed that ESBL-producing Enterobacteriaceae are widely disseminated in Indochinese countries, such as Thailand, Laos, and Vietnam.

Varying high levels of faecal carriage of extended-spectrum beta-lactamase producing Enterobacteriaceae in rural villages in Shandong, China: implications for global health

Antibiotic resistance is considered a major threat to global health and is affected by many factors, of which antibiotic use is probably one of the more important. Other factors include hygiene, crowding and travel. The rapid resistance spread in Gram-negative bacteria, in particular extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae (ESBL-E), is a global challenge, leading to increased mortality, morbidity and health systems costs worldwide. Knowledge about resistance in commensal flora is limited, including in China. Our aim was to establish the faecal carriage rates of ESBL-E and find its association with known and suspected risk factors in rural residents of all ages in three socio-economically different counties in the Shandong Province, China. Faecal samples and risk-factor information (questionnaire) were collected in 2012. ESBL-E carriage was screened using ChromID ESBL agar. Risk factors were analysed using standard statistical methods. Data from 1000 individuals from three counties and in total 18 villages showed a high and varying level of ESBL-E carriage. Overall, 42% were ESBL-E carriers. At county level the carriage rates were 49%, 45% and 31%, respectively, and when comparing individual villages (n = 18) the rate varied from 22% to 64%. The high level of ESBL-E carriage among rural residents in China is an indication of an exploding global challenge in the years to come as resistance spreads among bacteria and travels around the world with the movement of people and freight. A high carriage rate of ESBL-E increases the risk of infection with multi-resistant bacteria, and thus the need for usage of last resort antibiotics, such as carbapenems and colistin, in the treatment of common infections.

The inoculum effect of antibiotics against CTX-M-extended-spectrum β-lactamase-producing Escherichia coli

BACKGROUND

Questions remain regarding the use of the cephalosporins to treat infections caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. For example, should ceftazidime or cefepime be used to treat infections with CTX-M ESBL-producing organisms with low MICs (minimum inhibitory concentrations), according to the new Clinical and Laboratory Standards Institute's (CLSI) recommendations for susceptibility testing? Some studies have reported that in vitro MICs of cephalosporins increase as the inoculum increases, which is the inoculum effect; however, most of the enzymes studied were SHV and TEM. In this study, we aimed to investigate the inoculum effect on ceftazidime, cefepime and four other β-lactam agents against CTX-M-ESBLs-producing Escherichia coli.

METHODS

Antibiotic susceptibilities were determined using broth microdilution MIC methodology according to the CLSI recommended with standard and 100-fold-higher inocula.

RESULTS

An inoculum effect on meropenem and cefminox was not detected. The size of the inoculum affected piperacillin/tazobactam activity against only 4 strains, all CTX-M-14 genotypes. The inoculum size affected the activity of ceftazidime, cefepime and cefotaxime against 35%, 85%, 100% of strains, respectively. Among the strains with an inoculum effect, CTX-M-14 was the most common ESBL genotype.

CONCLUSIONS

These findings suggest that meropenem is the most active compound against serious infections caused by Escherichia coli producing ESBLs. Cefminox and piperacillin-tazobactam exhibit strong activity against many strains. Until further studies are performed, clinicians should be aware that third- and fourth-generation cephalosporins (such as ceftazidime and cefepime) are not reliable for serious infections even though in vitro tests indicate susceptibility.

CTX-M-137, a hybrid of CTX-M-14-like and CTX-M-15-like β-lactamases identified in an Escherichia coli clinical isolate

OBJECTIVES

To characterize a novel CTX-M chimera, CTX-M-137, from Escherichia coli clinical isolates in China.

METHODS

Isolates were collected from five hospitals between 22 February 2009 and 20 December 2011. Resistance genes were investigated by PCR. blaCTX-M-137 was cloned and purified for kinetic measurements. Conjugation experiments, S1-PFGE and Southern blotting were performed to study the plasmid harbouring blaCTX-M-137. The genetic environment of blaCTX-M-137 was determined by genomic cloning and sequencing.

RESULTS

A total of 247 cephalosporin-resistant E. coli were identified. blaCTX-M group genes were the most prevalent extended-spectrum β-lactamase (ESBL) genes, with 71 isolates harbouring blaCTX-M-1 group genes and 137 isolates harbouring blaCTX-M-9 group genes. A novel chimera of CTX-M-14-like and CTX-M-15-like ESBLs, designated CTX-M-137, was identified from a 60-year-old man with a urinary tract infection. The N-terminus of CTX-M-137 matched CTX-M-14 and the C-terminus matched CTX-M-15. CTX-M-137 conferred resistance to ceftazidime, cefotaxime and aztreonam. Purified CTX-M-137 showed good hydrolytic activity against ceftazidime and cefotaxime, and was inhibited by clavulanic acid. The blaCTX-M-137 was carried on an ∼83 kb IncI1 plasmid. blaCTX-M-137 was carried on a complete transposition unit ISEcp1-blaCTX-M-137-Δorf477 inserted into yagA, which is part of the IncI1 plasmid backbone.

CONCLUSIONS

We identified a novel CTX-M chimera, CTX-M-137, with a CTX-M-14-like N-terminus and a CTX-M-15-like C-terminus. Our findings suggest an ongoing diversification of CTX-M-type ESBLs through recombination events.

Trends in human fecal carriage of extended-spectrum β-lactamases in the community: toward the globalization of CTX-M

In the last 10 years, extended-spectrum β-lactamase-producing enterobacteria (ESBL-E) have become one of the main challenges for antibiotic treatment of enterobacterial infections, largely because of the current CTX-M enzyme pandemic. However, most studies have focused on hospitalized patients, though today it appears that the community is strongly affected as well. We therefore decided to devote our investigation to trends in ESBL-E fecal carriage rates and comprehensively reviewed data from studies conducted on healthy populations in various parts of the world. We show that (i) community ESBL-E fecal carriage, which was unknown before the turn of the millennium, has since increased significantly everywhere, with developing countries being the most affected; (ii) intercontinental travel may have emphasized and globalized the issue; and (iii) CTX-M enzymes, especially CTX-M-15, are the dominant type of ESBL. Altogether, these results suggest that CTX-M carriage is evolving toward a global pandemic but is still insufficiently described. Only a better knowledge of its dynamics and biology will lead to further development of appropriate control measures.

Risk factors of fecal carriage with extended-spectrum β-lactamase-producing Enterobacteriaceae in hospitalized patients

BACKGROUND

Colonization of multidrug-resistant microorganisms is a potential source of cross transmission and subsequent infection. Screening of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) is not yet a routine practice in most hospitals.

METHODS

The purpose of this study was to investigate the risk factors of fecal carriage of ESBL-E in hospitalized patients. A total of 174 samples (from 97 patients) was collected. Screening test was accomplished using commercial chromogenic medium (ChromID ESBL agar; bioMérieux, Marcy l'Etoile, France). The presence of ESBLs of grown isolates was confirmed by Clinical and Laboratory Standards Institute guidelines. Analysis of the risk factors of ESBL-E carriage was performed by multivariate logistic regression.

RESULTS

Among the risk factors, multivariate analysis demonstrated that prolonged hospitalization (≥90 days) (odds ratio [OR], 6.76; 95% confidence interval [CI]: 1.17-39.23; P = .033), prolonged intensive care unit stay (≥14 days) (OR, 4.78; 95% CI: 1.70-13.42; P = .003), and methicillin-resistant Staphylococcus aureus carriage (OR, 3.29; 95% CI: 1.20-9.01; P = .020) were found to be significantly associated with fecal carriers.

CONCLUSION

This study clarified the characteristics and the risk factors of hospitalized patients carrying ESBL-E. In addition, the cost-benefit of routine screening in addition to methicillin-resistant Staphylococcus aureus and vancomycin-resitant Enterococci needs to be assessed.

Risk factors for community-acquired urinary tract infections caused by ESBL-producing enterobacteriaceae--a case-control study in a low prevalence country

Community-acquired urinary tract infection (CA-UTI) is the most common infection caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, but the clinical epidemiology of these infections in low prevalence countries is largely unknown. A population based case-control study was conducted to assess risk factors for CA-UTI caused by ESBL-producing E. coli or K. pneumoniae. The study was carried out in a source population in Eastern Norway, a country with a low prevalence of infections caused by ESBL-producing Enterobacteriaceae. The study population comprised 100 cases and 190 controls with CA-UTI caused by ESBL-producing and non-ESBL-producing E. coli or K. pneumoniae, respectively. The following independent risk factors of ESBL-positive UTIs were identified: Travel to Asia, The Middle East or Africa either during the past six weeks (Odds ratio (OR) = 21; 95% confidence interval (CI): 4.5–97) or during the past 6 weeks to 24 months (OR = 2.3; 95% CI: 1.1–4.4), recent use of fluoroquinolones (OR = 16; 95% CI: 3.2–80) and β-lactams (except mecillinam) (OR = 5.0; 95% CI: 2.1–12), diabetes mellitus (OR = 3.2; 95% CI: 1.0–11) and recreational freshwater swimming the past year (OR = 2.1; 95% CI: 1.0–4.0). Factors associated with decreased risk were increasing number of fish meals per week (OR = 0.68 per fish meal; 95% CI: 0.51–0.90) and age (OR = 0.89 per 5 year increase; 95% CI: 0.82–0.97). In conclusion, we have identified risk factors that elucidate mechanisms and routes for dissemination of ESBL-producing Enterobacteriaceae in a low prevalence country, which can be used to guide appropriate treatment of CA-UTI and targeted infection control measures.

Travel-associated faecal colonization with ESBL-producing Enterobacteriaceae: incidence and risk factors

OBJECTIVES

To study the acquisition of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) among the faecal flora during travel, with a focus on risk factors, antibiotic susceptibility and ESBL-encoding genes.

METHODS

An observational prospective multicentre cohort study of individuals attending vaccination clinics in south-east Sweden was performed, in which the submission of faecal samples and questionnaires before and after travelling outside Scandinavia was requested. Faecal samples were screened for ESBL-PE by culturing on ChromID ESBL and an in-house method. ESBL-PE was confirmed by phenotypic and genotypic methods. Susceptibility testing was performed with the Etest. Individuals who acquired ESBL-PE during travel (travel-associated carriers) were compared with non-carriers regarding risk factors, and unadjusted and adjusted ORs after manual stepwise elimination were calculated using logistic regression.

RESULTS

Of 262 enrolled individuals, 2.4% were colonized before travel. Among 226 evaluable participants, ESBL-PE was detected in the post-travel samples from 68 (30%) travellers. The most important risk factor in the final model was the geographic area visited: Indian subcontinent (OR 24.8, P < 0.001), Asia (OR 8.63, P < 0.001) and Africa north of the equator (OR 4.94, P = 0.002). Age and gastrointestinal symptoms also affected the risk significantly. Multiresistance was seen in 77 (66%) of the ESBL-PE isolates, predominantly a combination of reduced susceptibility to third-generation cephalosporins, trimethoprim/sulfamethoxazole and aminoglycosides. The most common species and ESBL-encoding gene were Escherichia coli (90%) and CTX-M (73%), respectively.

CONCLUSION

Acquisition of multiresistant ESBL-PE among the faecal flora during international travel is common. The geographical area visited has the highest impact on ESBL-PE acquisition.

The role of the natural environment in the emergence of antibiotic resistance in gram-negative bacteria

During the past 10 years, multidrug-resistant Gram-negative Enterobacteriaceae have become a substantial challenge to infection control. It has been suggested by clinicians that the effectiveness of antibiotics is in such rapid decline that, depending on the pathogen concerned, their future utility can be measured in decades or even years. Unless the rise in antibiotic resistance can be reversed, we can expect to see a substantial rise in incurable infection and fatality in both developed and developing regions. Antibiotic resistance develops through complex interactions, with resistance arising by de-novo mutation under clinical antibiotic selection or frequently by acquisition of mobile genes that have evolved over time in bacteria in the environment. The reservoir of resistance genes in the environment is due to a mix of naturally occurring resistance and those present in animal and human waste and the selective effects of pollutants, which can co-select for mobile genetic elements carrying multiple resistant genes. Less attention has been given to how anthropogenic activity might be causing evolution of antibiotic resistance in the environment. Although the economics of the pharmaceutical industry continue to restrict investment in novel biomedical responses, action must be taken to avoid the conjunction of factors that promote evolution and spread of antibiotic resistance.

Characteristics of extended-spectrum β-lactamase- and carbapenemase-producing Enterobacteriaceae Isolates from rivers and lakes in Switzerland

One of the currently most relevant resistance mechanisms in Enterobacteriaceae is the production of enzymes that lead to modern expanded-spectrum cephalosporin and even carbapenem resistance, mainly extended-spectrum β-lactamases (ESBLs) and carbapenemases. A worrisome aspect is the spread of ESBL and carbapenemase producers into the environment. The aim of the present study was to assess the occurrence of ESBL- and carbapenemase-producing Enterobacteriaceae and to further characterize ESBL- and carbapenemase-producing Enterobacteriaceae in rivers and lakes in Switzerland. ESBL-producing Enterobacteriaceae were detected in 21 (36.2%) of the 58 bodies of water sampled. One river sample tested positive for a carbapenemase-producing Klebsiella pneumoniae subsp. pneumoniae strain. Seventy-four individual strains expressing an ESBL phenotype were isolated. Species identification revealed 60 Escherichia coli strains, seven Klebsiella pneumoniae subsp. pneumoniae strains, five Raoultella planticola strains, one Enterobacter cloacae strain, and one Enterobacter amnigenus strain. Three strains were identified as SHV-12 ESBL producers, and 71 strains carried genes encoding CTX-M ESBLs. Of the 71 strains with CTX-M ESBL genes, 8 isolates expressed CTX-M-1, three produced CTX-M-3, 46 produced CTX-M-15, three produced CTX-M-55, one produced CTX-M-79, six produced CTX-M-14, and four produced CTX-M-27. Three of the four CTX-M-27 producers belonged to the multiresistant pandemic sequence type E. coli B2:ST131 that is strongly associated with potentially severe infections in humans and animals.

The novel CTX-M-116 β-lactamase gene discovered in Proteus mirabilis is composed of parts of the CTX-M-22 and CTX-M-23 genes

The novel β-lactamase gene bla(CTX-M-116) was identified in a Proteus mirabilis nosocomial isolate recovered from the urine of a patient in Moscow in 2005. DNA sequence analysis showed bla(CTX-M-116) to be a hybrid gene consisting of 5' bla(CTX-M-23) (nucleotides 1 to 278) and 3' bla(CTX-M-22) (nucleotides 286 to 876) moieties separated by an intervening putative site of recombination (GTTAAAT). A retrospective analysis of available bla(CTX-M) genes in the GenBank database revealed 19 bla(CTX-M) genes that display the same hybrid structure.

Fecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae in Korean community and hospital settings

PURPOSE

The assessment and early recognition of risk factors for infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are important for infection control and proper treatment. The aim of the present study was to investigate the prevalence of fecal carriage of ESBL-E in healthy individuals and hospitalized high-risk patients in Korea and to compare the characteristics of ESBL-E in these two groups.

METHODS

A total of 384 samples from 290 healthy individuals and 94 high-risk patients were collected. The screening of ESBL-E was performed using a commercial chromogenic medium. Bacterial identification and antibiotic susceptibility testing were performed using the Vitek 2 system.

RESULTS

The prevalence of ESBL-E carriage was 20.3 % in healthy individuals and 42.5 % in high-risk patients. Escherichia coli comprised a large majority (96.6 %) of the isolates from healthy individuals, but Klebsiella pneumoniae was more commonly detected (45.0 %) in high-risk patients than in healthy individuals. K. pneumoniae isolates exhibited significantly higher resistance to ceftazidime, ampicillin, and carbapenem, and E. coli exhibited higher resistance to cefotaxime. E. coli from high-risk patients exhibited significantly higher resistance to levofloxacin and cefepime than that from healthy individuals.

CONCLUSIONS

We demonstrated the high prevalence of ESBL-E carriage in Korea and clarified the characteristics of ESBL-E carriage in healthy individuals and high-risk patients. The distribution and antibiotic susceptibility of colonizing ESBL-E were different between the group of healthy individuals and the high-risk patients. Active surveillance of ESBL-E carriage is suggested for infection control, and the use of chromogenic agar appears to be an efficient method.

Epidemiology and genetics of CTX-M extended-spectrum β-lactamases in Gram-negative bacteria

CTX-M enzymes, the plasmid-mediated cefotaximases, constitute a rapidly growing family of extended-spectrum β-lactamases (ESBLs) with significant clinical impact. CTX-Ms are found in at least 26 bacterial species, particularly in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. At least 109 members in CTX-M family are identified and can be divided into seven clusters based on their phylogeny. CTX-M-15 and CTX-M-14 are the most dominant variants. Chromosome-encoded intrinsic cefotaximases in Kluyvera spp. are proposed to be the progenitors of CTX-Ms, while ISEcp1, ISCR1 and plasmid are closely associated with their mobilization and dissemination.

Proportion of extended-spectrum ß-lactamase-producing Enterobacteriaceae in community setting in Ngaoundere, Cameroon

BACKGROUND

There is no information regarding the resistance mechanisms of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae in community setting in Cameroon. The current study aimed to determine the proportion of ESBLs in Enterobacteriaceae isolated in the community and to analyse some risk factors associated with ESBL carriage.

METHODS

Faecal samples were collected from 208 different outpatients and 150 healthy student volunteers between 3 January and 3 April 2009. Enterobacterial isolates resistant to third-generation cephalosporins were screened for ESBL production by the double-disk synergy test. Presumptive ESBL-producing isolates with positive synergy test were identified by Mass Spectrometry using the BioTyper MALDI-TOF. For such ESBL positive isolates, antibiotic susceptibility was determined by the Vitek 2 system. PCR and sequencing were performed for the detection of different types of ESBL genes in presumptive ESBL-producing isolates. Statistical methods were used for the univariate calculation of risk factors.

RESULTS

During the study period, a total of 358 faecal samples were analysed; 58 of such samples (16%) showed an ESBL phenotype and were confirmed by PCR. The proportion of ESBL producers in faecal carriage was statistically different between outpatients and student volunteers (23.1% vs. 6.7%: p < 0.000). According to a univariate analysis, previous use of antibiotics (ciprofloxacin) appeared to be a risk factor for ESBL carriage (p < 0.05).Escherichia coli was the species most frequently isolated among the ESBL producers in outpatients (66.7%) and student volunteers (90%). Isolates showed additional resistance to gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole but none of them was resistant to temocillin, amikacin or meropenem. Most of the strains (97%) produced a CTX-M group 1 enzymes [CTX-M-15 (98%) or CTX-M-1 (2%)] and the remaining strains produced SHV-12 enzyme (3%).

CONCLUSIONS

The use of drugs such as amoxicillin, ciprofloxacin and trimethoprim/sulfamethoxazole does not seem appropriate for empirical treatment because of emerging resistance. The implementation in Cameroon or in other African countries of methods of screening ESBL-producing organisms in routine laboratories is of great importance in order for us to offer patients appropriate treatment and for infection control efforts to succeed.

Molecular identification of extended-spectrum-β-lactamase genes from Enterobacteriaceae isolated from healthy human carriers in Switzerland

In this study, fecal samples from 586 healthy humans were investigated to determine the occurrence of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae in Swiss people. A total of 5.8% of the human fecal samples yielded ESBL producers, and all of the 34 isolated strains were Escherichia coli. PCR analysis revealed that 14 strains produced CTX-M-15, 10 produced CTX-M-1, 7 strains produced CTX-M-14, and 2 strains produced CTX-M-2 ESBLs. One strain produced SHV-12 ESBL. Of the 34 isolates, 15 produced additional TEM-1 broad-spectrum β-lactamases. By serotyping, a high degree of diversity among the strains was found.

Rectal carriage of extended-spectrum beta-lactamase-producing gram-negative bacilli in community settings in Madagascar

Background

Extended-spectrum ß-lactamase-producing Enterobacteria (ESBL-PE) emerged at the end of the 1980s, causing nosocomial outbreaks and/or hyperendemic situations in hospitals and long-term care facilities. In recent years, community-acquired infections due to ESBL-PE have spread worldwide, especially across developing countries including Madagascar.

Objectives

This study aimed to determine the prevalence and risk factors of intestinal carriage of ESBL-PE in the community of Antananarivo.

Methods

Non-hospitalized patients were recruited in three health centers in different socio economic settings. Fresh stool collected were immediately plated on Drigalski agar containing 3 mg/liter of ceftriaxone. Gram-negative bacilli species were identified and ESBL production was tested by a double disk diffusion (cefotaxime and ceftazidime +/− clavulanate) assay. Characterization of ESBLs were perfomed by PCR and direct sequencing . Molecular epidemiology was analysed by Rep-PCR and ERIC-PCR.

Results

484 patients were screened (sex ratio  = 1.03, median age 28 years). 53 ESBL-PE were isolated from 49 patients (carrier rate 10.1%). The isolates included Escherichia coli (31), Klebsiella pneumoniae (14), Enterobacter cloacae (3), Citrobacter freundii (3), Kluyvera spp. (1) and Pantoae sp.(1). In multivariate analysis, only the socioeconomic status of the head of household was independently associated with ESBL-PE carriage, poverty being the predominant risk factor.

Conclusions

The prevalence of carriage of ESBL in the community of Antananarivo is one of the highest reported worldwide. This alarming spread of resistance genes should be stopped urgently by improving hygiene and streamlining the distribution and consumption of antibiotics.

High prevalence of bla(CTX-M) extended-spectrum β-lactamase genes in Escherichia coli isolates from pets and emergence of CTX-M-64 in China

As a cause of community-acquired infections, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli constitute an emerging public-health concern. Few data on the molecular epidemiology of ESBL-producing E. coli isolates from pets are available in China. Detection and characterization of ESBL genes (bla(CTX-M), bla(SHV) and bla(TEM)) was conducted among 240 E. coli isolates recovered from healthy and sick pets in South China from 2007 to 2008. The clonal relatedness of ESBL-producing E. coli isolates was assessed by pulsed field gel electrophoresis. ESBL-encoding genes were identified in 97 (40.4%) of the 240 isolates and 96 (40.0%) of them harbored CTX-M. The most common CTX-M types were CTX-M-14 (n = 45) and CTX-M-55 (n = 24). The recently reported CTX-M-64 was identified in three isolates. Isolates producing CTX-M-27, -15, -65, -24, -3 and -9 were also identified. Ten isolates carried two or three CTX-M types, with the combination of CTX-M-14 and CTX-M-55 being the most frequent (n = 6). ISEcp1 was identified in the upstream region of 93 out of the 107 bla(CTX-M) genes (86.9%). The sequence of the spacer region (45 bp) between ISEcp1 and the start codon of all bla(CTX-M-55) genes (except four) was identical to that of bla(CTX-M-64). No major clonal relatedness was observed among these CTX-M producers. It is suggested that the horizontal transfer of bla(CTX-M) genes, mediated by mobile elements, contributes to their dissemination among E. coli isolates from pets. Our finding of high prevalence of ESBL in E. coli of companion animal origin illustrates the importance of molecular surveillance in tracking CTX-M-producing E. coli strains in pets.

Molecular characterization and antimicrobial susceptibility testing of Escherichia coli isolates from patients with urinary tract infections in 20 Chinese hospitals

A total of 222 urinary Escherichia coli isolates from 20 tertiary hospitals in 15 different provinces and 4 municipalities in mainland China were characterized by antimicrobial susceptibility, phylogrouping, and the presence of plasmid-mediated quinolone resistance genes. A subset of 138 suspected extended-spectrum cephalosporinase (ESC) producers were examined for genes encoding cephalosporin resistance. Forty-three isolates harboring bla(CTX-M-14) or bla(CTX-M-15) were analyzed by pulsed-field gel electrophoresis (PFGE), and plasmids containing these genes were typed using PCR-based replicon typing (PBRT). Thirteen phylogroup B2 bla(CTX-M-14)- and bla(CTX-M-15)-positive isolates were analyzed by multilocus sequence typing (MLST). A frequent occurrence of resistance (>46%) was observed toward cephalosporins, gentamicin, and fluoroquinolones. Among the 222 isolates, 4 qnrS1, 4 qepA, and 16 aac(6')-Ib-cr genes were confirmed. Four major phylogroups (A, B1, B2, and D) and nontypeable isolates (NTs) were found among the isolates, with phylogroup D (54%) being the most common phylogroup. A total of 110 (80%) of the 138 screened isolates harbored bla(CTX-M) genes, with bla(CTX-M-14) (71%) and bla(CTX-M-15) (24%) being the most prevalent of these genes. Nine of the 13 CTX-M-15- or CTX-M-14-containing B2 isolates belonged to ST131. PFGE typing showed a high level of diversity, and plasmid analysis indicated a very large pool of different resistance plasmids mediating the spread of bla(CTX-M) genes in mainland China. An equally very high frequency of resistance and equally high levels of diversity in phylogroups, PFGE types, and plasmids were observed among community- and hospital-acquired E. coli isolates, indicating the presence of a large reservoir in the community and a long-term spread of cephalosporin resistance in China.

Analysis of risk factors for a high prevalence of extended-spectrum {beta}-lactamase-producing Enterobacteriaceae in asymptomatic individuals in rural Thailand

The prevalence of and risk factors associated with extended-spectrum β-lactamase (ESBL)-producing micro-organisms have not been well studied in healthy individuals. The aim of this study was to determine this in healthy individuals in Thailand. Stool samples and questionnaires obtained from 445 participants from three provinces in Thailand were analysed. The antimicrobial susceptibility of the isolates was assessed using phenotypic and genotypic methods. PCR analysis was performed to detect and group the bla(CTX-M) genes. The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae in the three provinces was as follows: 29.3 % in Nan (43/147), 29.9 % in Nakhon Si Thammarat (43/144) and 50.6 % in Kanchanaburi (78/154) (P<0.001). Of the 445 samples, 33 (7.4 %), 1 (0.2 %) and 127 (28.5 %) isolates belonged to the bla(CTX-M) gene groups I, III and IV, respectively. Escherichia coli was the predominant member of the Enterobacteriaceae producing CTX-M-type ESBLs (40/43, 39/43 and 70/78 isolates in Nan, Nakhon Si Thammarat and Kanchanaburi, respectively). No statistically significant association was observed between the presence of ESBL-producing bacteria and gender, age, education, food habits or antibiotic usage. However, the provinces that had the highest prevalence of ESBL-producing Enterobacteriaceae also had the highest prevalence of use and purchase of antibiotics without a prescription. Thus, this study revealed that faecal carriage of ESBL-producing Enterobacteriaceae is very high in asymptomatic individuals in Thailand, with some variations among the provinces. This high prevalence may be linked to antibiotic abuse.

Clinical and economic outcomes associated with community-acquired intra-abdominal infections caused by extended spectrum beta-lactamase (ESBL) producing bacteria in China

BACKGROUND

To compare clinical and economic outcomes in patients with community-acquired intra-abdominal infection (IAI) due to extended spectrum beta-lactamase (ESBL) producing (ESBL-positive) bacteria versus non-ESBL-producing (ESBL-negative) bacteria in China.

METHODS

This was a retrospective chart review study of patients hospitalized with community-acquired IAI due to ESBL-positive or ESBL-negative infections caused by Escherichia coli or Klebsiella spp. Data were collected from six hospitals in China that participated in the Study for Monitoring Antibiotic Resistance Trends (SMART) during 2006-2007. Outcomes included clinical response at discharge and following first-line antibiotic, number of antibiotic agents and classes, duration of hospitalization, and overall hospitalization and intravenous antibiotic costs.

RESULTS

Of the 85 patients included in the study, 32 (37.6%) had ESBL-positive and 53 (62.4%) had ESBL-negative infections; E. coli was responsible for 77.6% of infections. Infection resolved at discharge in 30 (93.8%) ESBL-positive and 48 (90.6%) ESBL-negative patients (P = NS). Fewer ESBL-positive patients achieved complete response following first-line antibiotics (56.3% versus 83.0%; P = 0.01). ESBL-positive patients required longer antibiotic treatment, more antibiotics, longer hospitalization (24.3 versus 14.6 days; 1.67-fold ratio; P = 0.001), and incurred higher hospitalization costs ( yen24,604 vs. yen13,788; $3604 vs. $2020; 1.78-fold ratio; P < 0.001).

CONCLUSIONS

Patients with ESBL-positive infection had similar resolution rates at discharge compared to those with ESBL-negative infection, despite poorer first-line antibiotic response. However, ESBL-positive infection led to significantly greater hospitalization cost and intravenous antibiotic cost, and longer hospital stay.