Extended-spectrum β-lactamase producing Escherichia coli: changing epidemiology and clinical impact

blaCTX-M-15 carried by IncF-type plasmids is the dominant ESBL gene in Escherichia coli and Klebsiella pneumoniae at a hospital in Ghana

Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases (ESBLs) are among the most multidrug-resistant pathogens in hospitals and are spreading worldwide. Horizontal gene transfer and spread of high-risk clones are involved in ESBL dissemination. Investigation of the resistance phenotypes of 101 consecutive clinical E. coli (n=58) and K. pneumoniae (n=43) isolated at the Komfo Anokye Teaching Hospital in Ghana over 3 months revealed 63 (62%) with an ESBL phenotype. All 63 had a blaCTX-M gene, and sequence analysis showed that 62 of these were blaCTX-M-15. blaCTX-M-15 was linked to ISEcp1 and orf477Δ in all isolates, and most isolates also carried blaTEM, aac(3)-II, aacA4cr, and/or blaOXA-30 genes on IncF plasmids. XbaI/pulsed-field electrophoresis showed heterogeneity among isolates of both species, suggesting that blaCTX-M-15 dissemination is caused by horizontal gene transfer rather than clonal spread of these species in Ghana.

Antimicrobial Non-Susceptibility of Escherichia coli from Outpatients and Patients Visiting Emergency Rooms in Taiwan

Longitudinal nationwide surveillance data on antimicrobial non-susceptibility and prevalence of extended-spectrum β-lactamases (ESBLs) as well as AmpC β-lactamases producers among Escherichia coli from different sources in the community settings are limited. Such data may impact treatment practice. The present study investigated E. coli from outpatients and patients visiting emergency rooms collected by the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program. A total of 3481 E. coli isolates were studied, including 2153 (61.9%) from urine and 1125 (32.3%) from blood samples. These isolates were collected biennially between 2002 and 2012 from a total of 28 hospitals located in different geographic regions of Taiwan. Minimum inhibitory concentrations (MIC) were determined using methods recommended by the Clinical Laboratory Standards Institute (CLSI). The prevalence and factors associated with the presence of ESBL and AmpC β-lactamase-producers were determined. Significant increases in non-susceptibility to most β-lactams and ciprofloxacin occurred during the study period. By 2012, non-susceptibility to cefotaxime and ciprofloxacin reached 21.1% and 26.9%, respectively. The prevalence of ESBL- and AmpC- producers also increased from 4.0% and 5.3%, respectively, in 2002–2004, to 10.7% for both in 2010–2012 (P < 0.001). The predominant ESBL and AmpC β-lactamase genes were CTX-M and CMY-types, respectively. Non-susceptibility of urine isolates to nitrofurantoin remained at around 8% and to fosfomycin was low (0.7%) but to cefazolin (based on the 2014 CLSI urine criteria) increased from 11.5% in 2002–2004 to 23.9% in 2010–2012 (P <0.001). Non-susceptibility of isolates from different specimen types was generally similar, but isolates from elderly patients were significantly more resistant to most antimicrobial agents and associated with the presence of ESBL- and AmpC- β-lactamases. An additional concern is that decreased ciprofloxacin susceptibility (MIC 0.12–1 mg/L) was as high as 25% in isolates from all age groups, including those from pediatric patients. Our data indicated that there is a need to re-evaluate appropriate treatment selection for community-acquired infections in Taiwan. Identification of community reservoirs of multidrug-resistant E. coli is also warranted.

Prevalence and Risk Factors for Colonization With Extended-Spectrum Cephalosporin-Resistant Escherichia coli in Children Attending Daycare Centers: A Cohort Study in the Netherlands

BACKGROUND

The purpose of this study was to determine the prevalence and risk factors for colonization with extended-spectrum cephalosporin-resistant (ESC-R) Escherichia coli in daycare center (DCC)-attending children.

METHODS

This is a prospective cohort study including 44 DCCs in the Netherlands, combining DCC characteristics and monthly collected stool samples from their attendees, and was performed in 2010-2012. During a 22-month study period, 852 stool samples were collected and screened for ESC-R E coli. Risk factors were studied using logistic regression analysis.

RESULTS

In DCC-attending children (<4 years old), the overall prevalence of ESC-R E coli was 4.5%, and it was 8% in <1-year-old attendees. Among the 38 children carrying ESC-R E coli, the most common types were blaCMY-2 (26%), blaCTX-M-1 (16%), and chromosomal AmpC type 3 promoter mutants (13%). Extended-spectrum cephalosporin-resistant E coli was less common in DCCs where stricter hygiene protocols were enforced, eg, not allowing ill children to enter the DCC (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.14-0.84), performing extra checks on handwashing of ill children (OR, 0.42; 95% CI, 0.20-0.87), and reporting suspected outbreaks to local health authorities (OR, 0.27; 95% CI, 0.11-0.69).

CONCLUSIONS

The distribution of ESC-R E coli types in DCCs differs from that of the general population. Extended-spectrum cephalosporin-resistant E coli carriage in DCC-attending children is associated with the hygiene policies enforced in the DCC. Although our results are not conclusive enough to change current DCC practice beyond ensuring compliance with standing policies, they generated hypotheses and defined the degree of ESC resistance among DCC attendees, which may influence empiric antibiotic therapy choices, and tracked the increasing trend in ESC resistance.

Infection control implications of heterogeneous resistance mechanisms in carbapenem-resistant Enterobacteriaceae (CRE)

The Centers for Disease Control and Prevention (CDC) defines carbapenem-resistant Enterobacteriaceae (CRE) based upon a phenotypic demonstration of carbapenem resistance. However, considerable heterogeneity exists within this definitional umbrella. CRE may mechanistically differ by whether they do or do not produce carbapenemases. Moreover, patients can acquire CRE through multiple pathways: endogenously through antibiotic selective pressure on intestinal microbiota, exogenously through horizontal transmission or through a combination of these factors. Some evidence suggests that non-carbapenemase-producing CRE may be more frequently acquired by antibiotic exposure and carbapenemase-producing CRE via horizontal transmission, but definitive data are lacking. This review examines types of CRE resistance mechanisms, antibiotic exposure and horizontal transmission pathways of CRE acquisition, and the implications of these heterogeneities to the development of evidence-based CRE healthcare epidemiology policies. In our Expert Commentary & Five-Year View, we outline specific nosocomial CRE knowledge gaps and potential methodological approaches for their resolution.

Extended-spectrum β-lactamase infections during pregnancy: a growing threat

Extended-spectrum β-lactamases (ESBLs) are rapidly evolving plasmid transferrable enzymes that confer unique patterns of antibiotic resistance on various bacterial species. Such organisms pose special challenges to laboratory identification, as well as antibiotic selection, administration, and follow-up. Although such infections are increasingly common in the obstetric population, issues surrounding ESBLs are not widely recognized by practicing obstetricians, and controversies exist regarding diagnosis and management. This article provides the practitioner with a summary of clinically pertinent information that will assist in the proper care of pregnant patients with ESBL infection.

Intestinal decolonization of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBL): a retrospective observational study in patients at risk for infection and a brief review of the literature

Background

Multidrug-resistant Escherichia coli and other enteric bacteria producing extended-spectrum β-lactamases (ESBL) have emerged as an important cause of invasive infection. Targeting the primary (intestinal) niche by decolonization may be a valuable approach to decrease the risk of relapsing infections and to reduce transmission of ESBL-producing enteric pathogens.

Methods

In a retrospective observational study we evaluated the efficacy of intestinal decolonization treatment using orally administered colistin or other non-absorbable agents given for 2 to 4 weeks in adult patients with previous relapsing infection and persistent intestinal colonization with ESBL-positive Enterobacteriaceae (ESBL-E). Eradication success was defined as negative rectal swab or stool culture at the end of treatment and at follow up-2 weeks after treatment discontinuation.

Results

First-line decolonization treatment led to eradication of ESBL-E in 19/45 patients (42 %, 7/18 low-dose [4 × 1 million units] colistin, 3/12 high-dose [4 × 2 million units] colistin, 9/15 rifaximin [2 × 400 mg]), and secondary/salvage treatment was successful in 8/13 patients (62 %, 20 treatment episodes). Late follow-up showed that 7/13 patients (54 %) with successful initial or salvage decolonization became recolonized within 3 months after post-treatment assessment while all eight of the patients failing initial or salvage decolonization treatment with late follow-up remained colonized. A narrative review of the literature confirms the limited efficacy of non-absorbable antibiotics including conventional selective digestive tract decolonization (SDD)-like combination regimens for eradicating multidrug-resistant enteric bacteria from the intestinal tract.

Conclusions

At present, there is no clear evidence of a significant decolonization efficacy using single-drug treatment with oral non-absorbable antibiotics. More effective regimens are needed and a better definition of at risk patients is required for planning meaningful randomized controlled studies in this field.

Pathogenic Escherichia coli producing Extended-Spectrum β-Lactamases isolated from surface water and wastewater

To assess public health risks from environmental exposure to Extended-Spectrum β-Lactamases (ESBL)-producing bacteria, it is necessary to have insight in the proportion of relative harmless commensal variants and potentially pathogenic ones (which may directly cause disease). In the current study, 170 ESBL-producing E. coli from Dutch wastewater (n = 82) and surface water (n = 88) were characterized with respect to ESBL-genotype, phylogenetic group, resistance phenotype and virulence markers associated with enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), extraintesinal E. coli (ExPEC), and Shiga toxin-producing E. coli (STEC). Overall, 17.1% of all ESBL-producing E. coli were suspected pathogenic variants. Suspected ExPECs constituted 8.8% of all ESBL-producing variants and 8.3% were potential gastrointestinal pathogens (4.1% EAEC, 1.8% EPEC, 1.2% EIEC, 1.2% ETEC, no STEC). Suspected pathogens were significantly associated with ESBL-genotype CTX-M-15 (X² = 14.7, P < 0.001) and phylogenetic group B2 (X² = 23.5, P < 0.001). Finally, 84% of the pathogenic ESBL-producing E. coli isolates were resistant to three or more different classes of antibiotics. In conclusion, this study demonstrates that the aquatic environment is a potential reservoir of E. coli variants that combine ESBL-genes, a high level of multi-drug resistance and virulence factors, and therewith pose a health risk to humans upon exposure.

Stenotrophomonas maltophilia Infections in Adults: Primary Bacteremia and Pneumonia

Background:

Stenotrophomonas maltophilia is the third most frequent non-fermentative Gram-negative bacilli in nosocomial infections, and usually causes severe infections such as primary bacteremia and pneumonia.

Objectives:

The current study aimed to compare the demographic and clinical characteristics, microbiological findings and final outcomes of the patients with primary bacteremia and nosocomial pneumonia caused by S. maltophilia.

Patients and Methods:

The current study retrospectively evaluated patients aged 18 years and above with primary bacteremia and nosocomial pneumonia caused by S. maltophilia from January 2006 to December 2013. Medical records of patients, including reports of clinical microbiology and hospital infection control committee, were evaluated.

Results:

A total of 71 patients with S. maltophilia nosocomial infections, 35 (49.3%) primary bacteremia and 36 (50.7%) pneumonia, were diagnosed. There were no significant differences in gender, age, and co-morbid diseases, except chronic obstructive pulmonary disease; this infection was significantly higher in patients with pneumonia. A slightly higher 14-day mortality was found in patients with pneumonia, but the difference was not statistically significant. Inappropriate antibiotic use and presence of multiple organ dysfunction syndrome were found as independent risk factors for 14-day mortality in multivariate analysis.

Conclusions:

A slightly higher mortality in patients with pneumonia, caused by S. maltophilia, was strived to explain by advanced age, higher acute physiology and chronic health evaluation (APACHE II) and sepsis related organ failure assessment (SOFA) score, and also higher inappropriate antibiotic use.

Prevalence and characteristics of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae isolated from rural well water in Taian, China, 2014

The production of extended-spectrum beta-lactamase (ESBL) is one of the major antimicrobial resistance mechanisms in Enterobacteriaceae, and the increasing number of ESBL-producing Enterobacteriaceae isolated from water environments has posed a serious threat to the public health. The study aimed to analyze prevalence and characterization of ESBL-producing Enterobacteriaceae from rural well waters in Taian, China. A total of 10 isolates expressing an ESBL phenotype, including 9 Escherichia coli (E. coli) and 1 Klebsiella pneumoniae (K. pneumoniae) was obtained from 4 (4%) out of the 100 sampled wells. ESBL genotype revealed that 9 expressed CTX-M-15 and 1 produced CTX-M-27. Five out of 8 ESBL-producing E. coli expressing CTX-M-15 belonged to ST10, which are mostly detected from human feces in China. Importantly, the only strain of CTX-M-27-producing E. coli belonged to multi-locus sequence type B2:131 (ST131), which may be related with severe infection in humans and animals.

Antimicrobial resistance in hospital-acquired gram-negative bacterial infections

Aerobic gram-negative bacilli, including the family of Enterobacteriaceae and non-lactose fermenting bacteria such as Pseudomonas and Acinetobacter species, are major causes of hospital-acquired infections. The rate of antibiotic resistance among these pathogens has accelerated dramatically in recent years and has reached pandemic scale. It is no longer uncommon to encounter gram-negative infections that are untreatable using conventional antibiotics in hospitalized patients. In this review, we provide a summary of the major classes of gram-negative bacilli and their key mechanisms of antimicrobial resistance, discuss approaches to the treatment of these difficult infections, and outline methods to slow the further spread of resistance mechanisms.

In vitro activities of 21 antimicrobial agents alone and in combination with aminoglycosides or fluoroquinolones against extended-spectrum-β-lactamase-producing Escherichia coli isolates causing bacteremia

We evaluated the in vitro activity of various antimicrobials alone and in combination against 291 extended-spectrum-β-lactamase-producing Escherichia coli (ESBL-EC) isolates causing bacteremia in South Korean hospitals. Ceftazidime, cefepime, and piperacillin-tazobactam in combination with amikacin showed greater activity than found in combination with ciprofloxacin. In settings with a high prevalence of ESBL-producing pathogens, combination aminoglycoside antimicrobial therapy, especially with amikacin, may be considered for empirical therapy against suspected Gram-negative sepsis as a carbapenem-saving strategy.

Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates in Mongolia

BACKGROUND/PURPOSE

The aim of this study was to determine the molecular characteristics of β-lactamase genes in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates from Mongolia.

METHODS

Fifty-six ESBL-producing Enterobacteriaceae isolates were collected, of which 46 were Escherichia coli, seven were Klebsiella pneumoniae, and three were K. oxytoca. Minimum inhibitory concentrations for selected antibiotics were tested using the agar dilution method, and the β-lactamase genes were determined using polymerase chain reaction combined with sequencing. Pulsed-field gel electrophoresis (PFGE) was used for genotyping all isolates, and phylogenetic grouping was performed on ESBL-producing E. coli isolates. Conjugation tests combined with plasmid digestion assays were used to determine whether there was a horizontal spread in Mongolia.

RESULTS

Among the 56 ESBL-producing isolates, 43 isolates (76.8%) were resistant to fluoroquinolones, but all isolates were susceptible to carbapenems and amikacin. The polymerase chain reaction sequencing results showed that the dominant CTX-M genotype was CTX-M-15 (19/46, 41.3%) in the ESBL-producing E. coli isolates. By contrast, CTX-M-14 and CTX-M-3 were the major genotypes found in Klebsiella spp. Phylogenetic analysis revealed that 21 ESBL-producing E. coli isolates belonged to group D (21/46, 45.6%), followed by group A (13/46, 28.3%), group B2 (11/46, 23.9%), and group B1 (1/46, 2.2%). Only four E. coli isolates (4/46, 8.7%) belonged to the ST131 clone. PFGE showed that the ESBL-producing Enterobacteriaceae were genetically unrelated. The conjugation assay showed that two plasmids harboring CTX-M-15 in E. coli isolates were genetic unrelated, whereas seven plasmids harboring CTX-M-14 (5/7 and 2/7) and four plasmids harboring CTX-M-55 (4/4) showed genetic relatedness, indicating the dissemination of resistance plasmids in this area.

ESBL Escherichia coli Ventriculitis after Aneurysm Clipping: A Rare and Difficult Therapeutic Challenge

Background. Extended spectrum beta-lactamase (ESBL) produced Escherichia coli (E. coli) ventriculitis is a rare infection of the central nervous system, with increasing rarity in the adult population. The therapeutic strategy to achieve cure may need to involve a combination of intraventricular and intravenous (IV) therapy. Objective. To describe a case of ESBL E. coli meningitis/ventriculitis in an adult and outline the antimicrobial therapy that leads to cure. Methods. We retrospectively reviewed the records of a patient admitted to the neurosurgical department for aneurysmal subarachnoid hemorrhage, who developed ESBL E. coli ventriculitis. Results. A 55-year-old female, admitted for a Fisher grade 3, World Federation of Neurological Surgeons grade 1, subarachnoid hemorrhage, developed ESBL E. coli ventriculitis requiring a combination of intraventricular gentamicin and high dose intravenous meropenem for clearance. Cerebrospinal fluid clearance occurred at 7 days after initiation of combined therapy. The patient remained shunt dependent. Conclusions. Meningitis and ventriculitis caused by ESBL E. coli species are rare and pose significant challenges to the treating physician. Early consideration for combined intraventricular and IV therapy should be made.

Risk factors and scoring system for predicting bacterial resistance to cefepime as used empirically in haematology wards

OBJECTIVES

Bacterial resistance is of growing concern in haematology wards. As the inappropriate administration of empirical antibacterial may alter survival, we studied risk factors for resistance to our usual empirical first-line antibacterial therapy, cefepime.

METHODS

We retrospectively studied 103 first episodes of bacteraemia recorded in our haematology department over 2.5 years. Risk factors for cefepime-resistance were identified by multivariate logistic regression with backward selection (P < 0.05). A scoring system for predicting cefepime-resistance was built on independent factor, with an internal validation by the bootstrap resampling technique.

RESULTS

38 (37%) episodes were due to Gram-negative bacteria. Fifty (49%) were due to bacteria resistant to cefepime. Cefepime resistance was significantly associated with a decreased survival at day 30 (P < 0.05). Three risk factors were independently associated with cefepime-resistance: acute lymphoblastic leukaemia; ≥18 days since hospital admission; and receipt of any β-lactam in the last month. Patients with ≥2 of these risk factors had a probability of 86% (CI 95%, 25 to 100%) to carry a cefepime-resistant strain.

CONCLUSION

Using our scoring system should reduce the indication of very broad antibacterial regimens in the empirical, first-line treatment of febrile hematology patients in more than 80% of the cases.

War wound treatment complications due to transfer of an IncN plasmid harboring bla(OXA-181) from Morganella morganii to CTX-M-27-producing sequence type 131 Escherichia coli

A 22-year-old male developed a recurrent sacral abscess associated with embedded shrapnel following a blast injury. Cultures grew extended-spectrum β-lactamase (ESBL)-producing, carbapenem-susceptible Escherichia coli. Ertapenem was administered, but the infection recurred after each course of antibiotics. Initial surgical interventions were unsuccessful, and subsequent cultures yielded E. coli and Morganella morganii, both nonsusceptible to carbapenems. The isolates were Carba NP test negative, gave ambiguous results with the modified Hodge test, and amplified the bla(OXA48)-like gene by real-time PCR. All E. coli isolates were sequence type 131 (ST131), carried nine resistance genes (including bla(CTX-M-27)) on an IncF plasmid, and were identical by genome sequencing, except for 150 kb of plasmid DNA in carbapenem-nonsusceptible isolates only. Sixty kilobases of this was shared by M. morganii and represented an IncN plasmid harboring bla(OXA-181). In M. morganii, the gene was flanked by IS3000 and ISKpn19, but in all but one of the E. coli isolates containing bla(OXA-181), a second copy of ISKpn19 had inserted adjacent to IS3000. To the best of our knowledge, this is the first report of bla(OXA-181) in the virulent ST131 clonal group and carried by the promiscuous IncN family of plasmids. The tendency of M. morganii to have high MICs of imipenem, a bla(OXA-181) substrate profile that includes penicillins but not extended-spectrum cephalosporins, and weak carbapenemase activity almost resulted in the presence of bla(OXA-181) being overlooked. We highlight the importance of surveillance for carbapenem resistance in all species, even those with intrinsic resistances, and the value of advanced molecular techniques in detecting subtle genetic changes.

The Challenge of Antimicrobial Resistance in Managing Intra-Abdominal Infections

BACKGROUND

In recent years, there has been a worldwide increase in infections caused by microorganisms resistant to multiple antimicrobial agents.

METHODS

In the past few decades, an increased prevalence of infections caused by antibiotic-resistant pathogens, including Enterococcus spp., carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella spp., carbapenemase-producing Klebsiella pneumoniae, and resistant Candida spp., also has been observed among intra-abdominal infections (IAIs).

RESULTS

The increasing prevalence of multi-drug resistance is responsible for a substantial increase in morbidity and mortality rates associated with IAIs.

CONCLUSIONS

It is necessary for every surgeon treating IAIs to understand the underlying epidemiology and clinical consequences of antimicrobial resistance. Emergence of drug resistance, combined with the lack of new agents in the drug development pipeline, indicates that judicious antimicrobial management will be necessary to preserve the utility of the drugs available currently.

Agriculture and food animals as a source of antimicrobial-resistant bacteria

One of the major breakthroughs in the history of medicine is undoubtedly the discovery of antibiotics. Their use in animal husbandry and veterinary medicine has resulted in healthier and more productive farm animals, ensuring the welfare and health of both animals and humans. Unfortunately, from the first use of penicillin, the resistance countdown started to tick. Nowadays, the infections caused by antibiotic-resistant bacteria are increasing, and resistance to antibiotics is probably the major public health problem. Antibiotic use in farm animals has been criticized for contributing to the emergence of resistance. The use and misuse of antibiotics in farm animal settings as growth promoters or as nonspecific means of infection prevention and treatment has boosted antibiotic consumption and resistance among bacteria in the animal habitat. This reservoir of resistance can be transmitted directly or indirectly to humans through food consumption and direct or indirect contact. Resistant bacteria can cause serious health effects directly or via the transmission of the antibiotic resistance traits to pathogens, causing illnesses that are difficult to treat and that therefore have higher morbidity and mortality rates. In addition, the selection and proliferation of antibiotic-resistant strains can be disseminated to the environment via animal waste, enhancing the resistance reservoir that exists in the environmental microbiome. In this review, an effort is made to highlight the various factors that contribute to the emergence of antibiotic resistance in farm animals and to provide some insights into possible solutions to this major health issue.

Multidrug resistance found in extended-spectrum beta-lactamase-producing Enterobacteriaceae from rural water reservoirs in Guantao, China

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae have been isolated from humans and animals across the world. However, data on prevalence of ESBL-producing Enterobacteriaceae from rural water reservoirs is limited. This study aimed to isolate and characterize ESBL-producing Enterobacteriaceae in rural water reservoirs in Guantao, China. ESBL-producing Enterobacteriaceae were found in 5 (16.7%) of 30 sampled rural water reservoirs. Sixty-six individual isolates expressing an ESBL phenotype were obtained in the present study. Species identification showed that 42 representatives of Escherichia coli, 17 Klebsiella pneumoniae, 4 Raoultella planticola, and 3 Enterobacter cloacae. Twenty isolates contained a single bla gene, including CTX-M (17 strains), TEM (2 strains), and SHV (1 strain). Forty-six isolates contained more than one type of beta-lactamase genes. ESBL-producing Enterobacteriaceae isolated in this study were all multidrug resistant. These findings indicated that the serious contamination of ESBL-producing Enterobacteriaceae in rural water reservoirs existed in Guantao, China.

Clinical epidemiology and molecular analysis of extended-spectrum-β-lactamase-producing Escherichia coli in Nepal: characteristics of sequence types 131 and 648

Recently, CTX-M-type extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli strains have emerged worldwide. In particular, E. coli with O antigen type 25 (O25) and sequence type 131 (ST131), which is often associated with the CTX-M-15 ESBL, has been increasingly reported globally; however, epidemiology reports on ESBL-producing E. coli in Asia are limited. Patients with clinical isolates of ESBL-producing E. coli in the Tribhuvan University teaching hospital in Kathmandu, Nepal, were included in this study. Whole-genome sequencing of the isolates was conducted to analyze multilocus sequence types, phylotypes, virulence genotypes, O25b-ST131 clones, and distribution of acquired drug resistance genes. During the study period, 105 patients with ESBL-producing E. coli isolation were identified, and the majority (90%) of these isolates were CTX-M-15 positive. The most dominant ST was ST131 (n = 54; 51.4%), followed by ST648 (n = 15; 14.3%). All ST131 isolates were identified as O25b-ST131 clones, subclone H30-Rx. Three ST groups (ST131, ST648, and non-ST131/648) were compared in further analyses. ST648 isolates had a proportionally higher resistance to non-β-lactam antibiotics and featured drug-resistant genes more frequently than ST131 or non-ST131/648 isolates. ST131 possessed the most virulence genes, followed by ST648. The clinical characteristics were similar among groups. More than 38% of ESBL-producing E. coli isolates were from the outpatient clinic, and pregnant patients comprised 24% of ESBL-producing E. coli cases. We revealed that the high resistance of ESBL-producing E. coli to multiple classes of antibiotics in Nepal is driven mainly by CTX-M-producing ST131 and ST648. Their immense prevalence in the communities is a matter of great concern.

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.

Knowledge and understanding of antibiotic resistance and the risk of becoming a carrier when travelling abroad: A qualitative study of Swedish travellers

Background: Increasing globalisation, with the migration of people, animals and food across national borders increases the risk of the spread of antibiotic-resistant bacteria. To avoid becoming a carrier of antibiotic-resistant bacteria when travelling, knowledge about antibiotic resistance is important. Materials and methods: We aimed to describe the knowledge and understanding of antibiotic-resistant bacteria, and of the risk for becoming a carrier of such bacteria, among Swedish travellers before their travel to high-risk areas. A questionnaire with three open-ended questions was distributed to 100 individuals before departure. Results: The travellers’ answers were analysed using content analysis, resulting in the theme ‘To be an insecure traveller who takes control over one’s own journey’. Our results showed that the travellers were aware of what the term ‘antimicrobial resistance’ meant, but did not understand its real significance, nor the consequences for the individual nor for society. They also distanced themselves from the problem. Few thought that their travel would entail a risk of becoming a carrier of resistant bacteria. The lack of knowledge caused an uncertainty among the travellers, whom tried to master the situation by using coping strategies. They proposed a number of measures to prevent carriership. The measures were general and primarily aimed at avoiding illness abroad, particularly acute gastro-intestinal infection. Conclusions:In health care and vaccination clinics, there is a need for improved information for persons intending to travel to high-risk areas, both about the risks of contracting antibiotic- resistant bacteria and about effective preventive measures.

[Update on outbreaks reported from neonatal intensive care units: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa]

In terms of the unique risk profile, the clinical course of nosocomial infections, and the most prevalent bacterial pathogens, literature on outbreaks of potentially pathogenic bacteria on neonatal intensive care units (NICUs) needs to be analyzed separately from reports derived from other intensive care units. With the purpose of updating important information for those involved in outbreak management and fostering preventive efforts, this article summarizes the results of a systematic literature analysis, referring to an earlier publication by Gastmeier et al. This review focuses on NICU outbreaks caused by Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa.

Surveillance of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae at a comprehensive cancer center in Japan, 2009-2013

We examined the results of surveillance of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, which are pathogens known to cause nosocomial outbreaks, at a comprehensive cancer center in Japan over a 5-year period. We found that the admission prevalence and the incidence of ESBL-producing E coli increased during the study period, in contrast with ESBL-producing K pneumoniae, in which the parameters remained low throughout the study period.

Detection of the SHV genotype polymorphism of the extended-spectrum β-lactamase-producing Gram-negative bacterium

The prevalence of extended-spectrum β-lactamases (ESBLs) is due to the extensive usage of the extended-spectrum cephalosporins and leads to huge financial loss worldwide, whilst presenting a challenge to the clinical treatment. The aim of the present study was to delineate the frequency of ESBL occurrence in Enterobacteriaceae and confirm the SHV genotype. A random collection of 153 Escherichia coli isolates (E. coli) and 70 Klebsiella pneumoniae isolates were tested. The amplification products obtained by polymerase chain reaction were sequenced. Isolates with novel mutations were transformed to E. coli DH5 α. The minimum inhibitory concentration (MIC) was obtained by a microdilution method. The relevance ratio of ESBL was 67.7% and the proportion of the SHV β-lactamase gene (bla_SHV) was 18.5%. A new genotype of β-lactamase was demonstrated and submitted to GenBank. A total of 12 mutational sites were found in 28 ESBL-producing isolates, including four nonsense mutations. Sensitive-rates of 28 ESBL-producing isolates to imipenem were 100%, and resistant-rates to penicillin, amoxicillin and oxacillin were 100%. The MIC of DH5 α-F8 to penicillin, oxacillin, cefoxitin, cefotaxime, cefepime, cefoperazone/sulbactam, imipenem and netilmicin was 512, 512, 2, 0.03, 0.06, 4, 0.015 and 32 respectively. In conclusion, ESBL and SHV-28 is the most prevalent bla. Imipenem is the most effective antibiotic to ESBL, and the 4th-generation cephalosporins and β-lactamase inhibitor compound are also effective. ESBL is mediated by plasmids and able to spread among different Enterobacteriaceae. In conclusion, new mutations of the bla_SHV gene exist from at least 2010.

Antimicrobial resistance: risk associated with antibiotic overuse and initiatives to reduce the problem

Antimicrobial resistance is a global public health challenge, which has accelerated by the overuse of antibiotics worldwide. Increased antimicrobial resistance is the cause of severe infections, complications, longer hospital stays and increased mortality. Overprescribing of antibiotics is associated with an increased risk of adverse effects, more frequent re-attendance and increased medicalization of self-limiting conditions. Antibiotic overprescribing is a particular problem in primary care, where viruses cause most infections. About 90% of all antibiotic prescriptions are issued by general practitioners, and respiratory tract infections are the leading reason for prescribing. Multifaceted interventions to reduce overuse of antibiotics have been found to be effective and better than single initiatives. Interventions should encompass the enforcement of the policy of prohibiting the over-the-counter sale of antibiotics, the use of antimicrobial stewardship programmes, the active participation of clinicians in audits, the utilization of valid rapid point-of-care tests, the promotion of delayed antibiotic prescribing strategies, the enhancement of communication skills with patients with the aid of information brochures and the performance of more pragmatic studies in primary care with outcomes that are of clinicians' interest, such as complications and clinical outcomes.

Overview of ESBL-producing Enterobacteriaceae from a Nordic perspective

Extended spectrum β-lactamases (ESBL) are increasing rapidly worldwide. E. coli producing CTX-M type ESBLs are the most common clinically encountered. The majority of E. coli ESBL infections are represented by urinary tract infections, but they can also cause severe infections, for example, in the blood stream and central nervous system. Since E. coli is a common colonizer of the normal gut microbiota, increasing prevalence of ESBL-producing strains is particularly worrisome. Once disseminated in the community, containment of this resistance type will be challenging. The driver of ESBL-producing Enterobacteriaceae (EPE) is debated. Some suggest that the ESBL genes were introduced to particularly successful bacterial clones. Others imply that very successful plasmids drive the rapid dissemination. More research and epidemiological studies of strain types, plasmids and mobile genetic elements are needed for these questions to be answered. In order to combat, or at least slow down, the worrisome trend of increasing numbers of EPE more knowledge is also needed on persistence of EPE in carriers as well as better understanding of how antibiotic treatment and other risk factors affect persistence and further dissemination. This review aims at giving an overview of this global problem from a Nordic perspective.

Epidemiology of Enterobacteriaceae producing CTX-M type extended spectrum β-lactamase (ESBL)

Over the past 20 years, some Enterobacteriaceae mainly Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis have demonstrated acquisition of plasmids secreting ESBL. CTX-M type ESBL have been isolated worldwide and their incidence has increased dramatically and is still increasing leading to a major therapeutic issue. Currently more than 150 allelic variants of CTX-M have been identified. These enzymes are classified in five major phylogenetic groups based on their gene sequences: CTX-M -1, CTX-M-2, CTX-M-8, CTX-M-9, CTX-M-25; two additional groups have been reported recently: CTX-M-74 and CTX-M-75. The important dissemination of these enzymes has led to an increased use of carbapenems. Their global community and nosocomial dissemination is often associated with a virulent E. coli clone ST131 producing CTX-M-15.

Increased expression levels of chromosomal AmpC β-lactamase in clinical Escherichia coli isolates and their effect on susceptibility to extended-spectrum cephalosporins

Forty-nine clinical Escherichia coli isolates, both extended-spectrum β-lactamase (ESBL) negative and ESBL positive, were studied to investigate whether increased AmpC expression is a mechanism involved in cefoxitin resistance and if this influences the third-generation cephalosporin activity. Nine of 33 (27.2%) cefoxitin-resistant (minimum inhibitory concentration [MIC] >8 mg/L) isolates showed hyperproduction of chromosomal AmpC (c-AmpC) based on (1) at least two positive tests using AmpC inhibitors, (2) mutations in the promoter/attenuator regions, and (3) a 6.1- to 163-fold increase in c-ampC expression by quantitative reverse transcription-polymerase chain reaction. In ESBL-negative isolates, MICs of ceftazidime and cefotaxime were mostly above the wild-type (WT) level, but below the S/I breakpoint (EUCAST guideline), except for one isolate with MICs of 4 mg/L. No plasmid-mediated AmpCs were found. Periplasmic extracts of nine c-AmpC hyperproducers were preincubated with or without cefuroxime or ceftazidime and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cefuroxime and ceftazidime were stable to hydrolysis but acted as inhibitors of the enzyme. None of these isolates showed loss of porins. Thus, cefoxitin resistance has low specificity for detecting upregulated c-AmpC production. c-AmpC hyperproducing E. coli is mostly still susceptible to third-generation cephalosporins but less than WT E. coli. Surveillance of cefoxitin-resistant E. coli to monitor developments in the activity of third-generation cephalosporins against c-AmpC hyperproducers is warranted.

Faecal carriage of extended-spectrumβ-lactamase (ESBL)-producing enterobacteria in liver disease patients from two hospitals in Egypt and France: a comparative epidemiological study

This study aimed to assess and compare the epidemiology of faecal carriage of extended spectrumβ-lactamase-producing enterobacteria (ESBL-E) in Hepatology departments of two hospitals specializing in liver diseases, Theodor Bilharz Research Institute (TBRI) in Cairo (Egypt) and Beaujon Hospital (Bj) in Clichy (France). CTX-M groups were identified by PCR, and TEM and SHV derivatives with the check-point system. Phylogenetic groups ofE. coliwere determined by multiplex PCR, and clone ST131 by PCR of genepabB. Prevalence of ESBL-E was 77·6% (45/58) in TBRI and 6·5% (13/199) in Bj (P < 10−7). Previous hospitalization was more common (P = 0·003) in Bj patients (93%) than in TBRI patients (45%) suggesting high prevalence of ESBL-E in the Egyptian community. The presence ofE. coliB2 ST131 among ESBL-E faecalE. coliin Egypt confirms its pervasiveness in the community and raises concern regarding this highly virulent and resistant clone.

Extended-spectrum β-lactamase-producing Escherichia coli isolation among older adults: epidemiology and outcomes

Clinical outcomes of older and younger adults with extended-spectrum β-lactamase-producing Escherichia coli isolation were compared. Two hundred thirty-two older adults (aged ≥65 years), and 145 younger adults with infection were identified between February 2010 and July 2011. After controlling for the propensity score and receipt of effective therapy, older adults were not at increased risk for adverse outcomes.

Inhibitor-resistant TEM- and OXA-1-producing Escherichia coli isolates resistant to amoxicillin-clavulanate are more clonal and possess lower virulence gene content than susceptible clinical isolates

In a previous prospective multicenter study in Spain, we found that OXA-1 and inhibitor-resistant TEM (IRT) β-lactamases constitute the most common plasmid-borne mechanisms of genuine amoxicillin-clavulanate (AMC) resistance in Escherichia coli. In the present study, we investigated the population structure and virulence traits of clinical AMC-resistant E. coli strains expressing OXA-1 or IRT and compared these traits to those in a control group of clinical AMC-susceptible E. coli isolates. All OXA-1-producing (n = 67) and IRT-producing (n = 45) isolates were matched by geographical and temporal origin to the AMC-susceptible control set (n = 56). We performed multilocus sequence typing and phylogenetic group characterization for each isolate and then studied the isolates for the presence of 49 virulence factors (VFs) by PCR and sequencing. The most prevalent clone detected was distinct for each group: group C isolates of sequence type (ST) 88 (C/ST88) were the most common in OXA-1 producers, B2/ST131 isolates were the most common in IRT producers, and B2/ST73 isolates were the most common in AMC-susceptible isolates. The median numbers of isolates per ST were 3.72 in OXA-1 producers, 2.04 in IRT producers, and 1.69 in AMC-susceptible isolates; the proportions of STs represented by one unique isolate in each group were 19.4%, 31.1%, and 48.2%, respectively. The sum of all VFs detected, calculated as a virulence score, was significantly higher in AMC-susceptible isolates than OXA-1 and IRT producers (means, 12.5 versus 8.3 and 8.2, respectively). Our findings suggest that IRT- and OXA-1-producing E. coli isolates resistant to AMC have a different and less diverse population structure than AMC-susceptible clinical E. coli isolates. The AMC-susceptible population also contains more VFs than AMC-resistant isolates.

[The threat of the carbapenemase-producing enterobacteriaceae in Spain: positioning report of the SEIMC study groups, GEIH and GEMARA]

The emergence and spread of carbapenemase-producing Enterobacteriaceae (CPE), as the current paradigm of extensive drug-resistance and multi-drug resistance to antibiotics, is a serious threat to patient health and public health. The increase in OXA-48- and VIM-1-producing Klebsiella pneumoniae isolates represents the greatest impact of CPE in Spain. This evidence has lead the members of a representative panel of the Spanish Study Groups of Nosocomial Infections and Mechanisms of Action and Resistance to Antimicrobials of the Spanish Society of Clinical Microbiology and Infectious Diseases (GEIH/GEMARA-SEIMC) to make a position statement expressing the need for: (i) definitive and coordinated action by all health professionals and authorities involved, and (ii) an adaptation of health systems to facilitate their early control and minimize their impact.

Impact of extended-spectrum β-lactamase-producing organisms on clinical and economic outcomes in patients with urinary tract infection

OBJECTIVE

To compare clinical and economic outcomes between patients with urinary tract infection (UTI) due to extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella species (ESBL-EK) versus patients with non-ESBL-EK UTI.

PATIENTS AND METHODS

Eighty-four (3.6%) of 2345 patients admitted between September 1, 2011 and August 31, 2012 with UTI were positive for ESBL-EK. Fifty-five ESBL-EK UTI (cases) and matched controls (non-ESBL-EK UTI) were included in the analysis. Clinical and economic outcomes were compared between cases and controls for statistical significance.

RESULTS

Cases were more likely to have diabetes mellitus, a history of recurrent UTIs, recently received antibiotics, recently been hospitalized, and had previous isolation of an ESBL-producing organism compared with controls. Failure of initial antibiotic regimen (62% vs 6%; P < 0.001) and time to appropriate antibiotic therapy (51 vs 2.5 hours; P < 0.001) were greater in cases. The median cost of care was greater (additional $3658; P = 0.02) and the median length of stay (LOS) prolonged for cases (6 vs 4 days; P = 0.02) despite similar hospital reimbursement (additional $469; P = 0.56). Although not significant, infection-related mortality (7.2% vs 1.8%) and 30-day UTI readmission (7.2% vs 3.6%) were higher in ESBL-EK cases.

CONCLUSIONS

UTI caused by ESBL-EK is associated with significant clinical and economic burden. The cost of care and LOS of patients with ESBL-EK UTI were 1.5 times those caused by non-ESBL-EK. Importantly, the additional cost of care is a liability to the hospital, as this is not offset by reimbursement. Appropriate and timely initial antibiotics may minimize the ESBL-EK impact on outcomes of patients with UTI.

Characterization of third-generation cephalosporin-resistant Escherichia coli from bloodstream infections in Denmark

The aim of the study was to investigate the molecular epidemiology of 87 third-generation cephalosporin-resistant Escherichia coli (3GC-R Ec) from bloodstream infections in Denmark from 2009. Sixty-eight of the 87 isolates were extended-spectrum beta-lactamase (ESBL) producers, whereas 17 isolates featured AmpC mutations only (without a coexpressed ESBL enzyme) and 2 isolates were producing CMY-22. The majority (82%) of the ESBL-producing isolates in our study were CTX-M-15 producers and primarily belonged to phylogroup B2 (54.4%) or D (23.5%). Further, one of the two CMY-22-producing isolates belonged to B2, whereas only few of the other AmpCs isolates belonged to B2 and D. Pulsed-field gel electrophoresis revealed that both clonal and nonclonal spread of 3GC-R Ec occurred. ST131 was detected in 50% of ESBL-producing isolates. The remaining ESBL-producing isolates belonged to 17 other sequence types (STs), including several other internationally spreading STs (e.g., ST10, ST69, and ST405). The majority (93%) of the ESBL-producing isolates and one of the CMY-22-producing isolates were multiresistant. In conclusion, 3GC-R in bacteriaemic E. coli in Denmark was mostly due to ESBL production, overexpression of AmpC, and to a lesser extent to plasmid-mediated AmpC. The worldwide disseminated CTX-M-15-ST131 was strongly represented in this collection of Danish, bacteriaemic E. coli isolates.

Clinical impact of fluoroquinolone-resistant Escherichia coli in the fecal flora of hematological patients with neutropenia and levofloxacin prophylaxis

BACKGROUND

Fluoroquinolone prophylaxis in patients with neutropenia and hematological malignancies is said to be effective on febrile netropenia (FN)-related infection and mortality; however, the emergence of antibiotic resistance has become a concern. Ciprofloxacin and levofloxacin prophylaxis are most commonly recommended. A significant increase in the rate of quinolone-resistant Escherichia coli in fecal flora has been reported following ciprofloxacin prophylaxis. The acquisition of quinolone-resistant E. coli after levofloxacin use has not been evaluated.

METHODS

We prospectively examined the incidence of quinolone-resistant E. coli isolates recovered from stool cultures before and after levofloxacin prophylaxis in patients with neutropenia from August 2011 to May 2013. Some patients received chemotherapy multiple times.

RESULTS

In this trial, 68 patients were registered. Levofloxacin-resistant E. coli isolates were detected from 11 and 13 of all patients before and after the prophylaxis, respectively. However, this was not statistically significant (P = 0.65). Multiple prophylaxis for sequential chemotherapy did not induce additional quinolone resistance among E. coli isolates. Interestingly, quinolone-resistant E. coli, most of which were extended-spectrum β-lactamase (ESBL) producers, were already detected in approximately 20% of all patients before the initiation of prophylaxis. FN-related bacteremia developed in 2 patients, accompanied by a good prognosis.

CONCLUSIONS

Levofloxacin prophylaxis for neutropenia did not result in a significant acquisition of quinolone-resistant E. coli. However, we detected previous colonization of quinolone-resistant E. coli before prophylaxis, which possibly reflects the spread of ESBL. The epidemic spread of resistant E. coli as a local factor may influence strategies toward the use of quinolone prophylaxis.

Food Safety: Emerging Pathogens

This article presents information related to emerging pathogens that are foodborne or have the potential to be foodborne including bacteria, viruses, and parasites. The phenotypic characteristics of these pathogens, their epidemiology, prevalence in foods, and transmission routes to humans as well as means for their control are also discussed.

Healthcare-associated infections in a department of urology: incidence and patterns of antibiotic resistance

OBJECTIVE

Healthcare-associated infections (HAIs) constitute a potentially severe complication which implies higher costs. A full knowledge of their microbiological characteristics and risk factors is of paramount importance for adequate management. The purpose of this study was to carry out an analysis of HAIs in patients admitted to a department of urology.

MATERIAL AND METHODS

Between November 2011 and October 2012, a prospective observational study was carried out analysing HAIs in patients admitted to the urology department of a tertiary care university hospital in Spain, reviewing the incidence and types of HAIs, the microorganisms isolated and patterns of resistance to antibiotics. Risk factors for HAIs were also evaluated.

RESULTS

HAIs were seen in 110 (6.5%) out of 1701 patients. Hypertension, a higher American Society of Anesthesiologists (ASA) score and surgery showed a statistical association with a higher risk of HAIs, and patients who underwent radical cystectomy had a high incidence of HAIs (10 out of 14). The most common HAIs were urinary tract infections (66.1%), followed by surgical site infections (16.5%), intra-abdominal abscesses (10.4%) and venous catheter-associated bacteraemia (6.1%). The most frequently isolated microorganisms were Escherichia coli (31.8%), then Enterococcus (17.6%) and Pseudomonas (12.9%). Escherichia coli showed resistance rates of 48.1% for ampicillin/amoxicillin plus β-lactamase inhibitor, 51.9% for fluoroquinolones, and 33.3% were extended-spectrum β-lactamase-producing E. coli. Pseudomonas aeruginosa showed a resistance rate of 36.4% for fluoroquinolones and carbapenems.

CONCLUSIONS

HAIs usually occur in patients with risk factors. Radical cystectomy is associated with a high incidence of HAIs. Microorganisms associated with HAIs show high rates of resistance, which must be taken into account when selecting appropriate antibiotic therapy.

Prevalence of extended-spectrum β-lactamase-producing multidrug-resistant Escherichia coli among isolates from community-acquired infections and in silico structural modeling of an ESBL protein

Escherichia coli is a common major cause of bacterial infections in tea tribe patients of the northeast region of Assam, India. In this study, we documented multidrug resistance (MDR) and the prevalence of extended-spectrum β-lactamases (ESBLs) among 148 E. coli strains that were isolated from bacterial infections in tea tribe patients who had a history of self-medication. High prevalence of resistance to ampicillin (82%), amoxicillin (68%), cefixime (60%), norfloxacin (60%), nalidixic acid (60%), and co-trimoxazole (53%) was observed. Of 148 E. coli isolates, 38 (26%) were confirmed as ESBL producers. The ESBL genes were sequenced from highly resistant ESBL producing E. coli isolates. Molecular modeling was performed using MODELLER 9v10 software to determine the three-dimensional structure of a protein. This result indicates that the prevailing reason for the high prevalence of antibiotic resistance in this community is prior exposure to low-quality antibiotics, hence MDR in E. coli is increasing. ESBLs are enzymes that are produced by resistant bacteria that hydrolyze advanced generations of cephalosporin antibiotics and cause resistance, even in patients with community-acquired infections. So our results provide a framework for understanding the structure and possible binding sites of ESBL proteins for drug targeting, and the results were found to be reliable.

Molecular epidemiology of CTX-M producing Enterobacteriaceae isolated from bloodstream infections in Rio de Janeiro, Brazil: emergence of CTX-M-15

Objective

The present study was designed to evaluate the molecular epidemiology of CTX-M producing Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli isolated from bloodstream infections at tertiary care hospitals in the State of Rio de Janeiro, Brazil.

Material and methods

A total of 231 nonduplicate Enterobacteriaceae were isolated from five Brazilian hospitals between September 2007 and September 2008. The antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical Laboratory Standard Institute. Isolates showing resistance to third-generation cephalosporins were screened for ESBL activity by the double-disk synergy test. The presence of bla_CTX-M, bla_CTX-M-15 and bla_KPC genes was determined by Polymerase Chain Reaction (PCR) amplification and DNA sequencing. The molecular typing of CTX-M producing isolates was performed by pulsed-field gel electrophoresis (PFGE).

Results and discussion

Ninety-three isolates were screened as ESBL positive and 85 (91%) were found to carry CTX-M-type, as follows: K. pneumoniae 59 (49%), E. cloacae 15 (42%), and E. coli 11 (15%). Ten isolates resistant for carbapenems in K. pneumoniae were bla_KPC-2 gene positive. Among CTX-M type isolates, CTX-M-15 was predominant in more than 50% of isolates for K. pneumoniae, E. coli, and E. cloacae. PFGE analysis of CTX-M producing isolates showed the predominance of CTX-M-15 in 10 of 24 pulsotypes in K. pneumoniae, 6 of 13 in E. cloacae and 3 of 6 in E. coli. CTX-M-15 was also predominant among KPC producing isolates. In conclusion, this study showed that CTX-M-15 was circulating in Rio de Janeiro state in 2007–2008. This data reinforce the need for continuing surveillance because this scenario may have changed over the years.