Producing Enterobacteriaceae Isolates Research Articles

Dissemination of IncFIIK-type plasmids in multiresistant CTX-M-15-producing Enterobacteriaceae isolates from children in hospital paediatric oncology wards

In this study, extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates in children with malignancies hospitalised at a paediatric oncology department in the Czech Republic were investigated. From June 2009 to January 2010, a total of 50 ESBL-producing faecal isolates of Enterobacteriaceae were obtained from 28 patients. These isolates were characterised with regard to ESBL enzymes, plasmid-mediated quinolone resistance genes, multilocus sequence typing (MLST) and plasmids conferring resistance to cephalosporins and fluoroquinolones. ESBL-producing isolates included Klebsiella pneumoniae (n=36), Escherichia coli (n=7), Klebsiella oxytoca (n=3), Enterobacter cloacae (n=2) and Citrobacter freundii (n=2). Klebsiella pneumoniae isolates belonged to 7 MLST types, including sequence types ST280, ST321, ST323 and ST416 as well as the novel types ST626, ST627 and ST628. The multiresistant epidemic clone E. coli B2-O25b-ST131 was detected in one patient. The gene blaCTX-M-15 was found on large conjugative IncFIIK plasmids along with blaTEM-1, blaOXA-1, qnrB1, aac(6′)-Ib-cr, strA, sul2, aac(3′)-II and tet(A) genes in most isolates. Dissemination of IncFIIK plasmids among various Enterobacteriaceae isolates was considered an important aspect of nosocomial colonisation in the wards by Enterobacteriaceae species producing ESBLs. This is the first study documenting multiple antibiotic resistance elements, including qnr genes, in IncFIIK plasmids in various bacterial species isolated in a single hospital department. The results highlight the evolution of IncFIIK plasmids into new variants containing novel antibiotic resistance elements and their important role in spreading ESBL-producing bacteria among hospitalised patients.

Bloodstream infections caused by IMP-8-producing Enterobacteriaceae isolates: the need for clinical laboratory detection of metallo-β-lactamases?

A retrospective study was conducted at a Taiwanese medical center to characterize bloodstream infections caused by IMP-8 metallo-β-lactamase (MBL)-producing Enterobacteriaceae isolates and to assess the need for laboratory detection of IMP producers. We analyzed 37 patients infected with IMP-8 producers (two Escherichia coli, nine Klebsiella pneumoniae, 25 Enterobacter cloacae, and one Citrobacter freundii) and 107 patients infected with non-IMP-8 producers (eight E. coli, 26 K. pneumoniae, 70 E. cloacae, and three C. freundii) that were interpreted as carbapenem-nonsusceptible based on the updated Clinical and Laboratory Standards Institute (CLSI) 2010 guidelines. Only 18 (48.6 %) of the IMP-8 producers were regarded as potential carbapenemase producers based on the CLSI 2012 guidelines. The production of extended-spectrum β-lactamases (ESBLs) was more common in the MBL group (73.0 %) than in the non-MBL group (41.1 %). There were no significant differences in carbapenem susceptibilities, clinical characteristics, carbapenem use for empirical and definitive treatment, and mortality rates between the two groups. Eighteen IMP-8 producers could be deemed as resistant to all carbapenems [minimum inhibitory concentration (MIC) of any carbapenem ≥2 μg/mL]; patients with these isolates had a lower, but non-significant, 28-day mortality rate (27.8 %) than patients infected with non-MBL producers having similar carbapenem MICs (39.0 %) (p = 0.41). A multivariate analysis revealed severity of acute illness as the single independent variable associated with both 7-day and 28-day mortality rates (p < 0.01) for infections caused by Enterobacteriaceae with decreased carbapenem susceptibilities. Our findings suggest that the clinical detection of IMP-producing Enterobacteriaceae is not required even when the "old" CLSI criteria are used.

New Delhi Metallo-β-Lactamase 4–producingEscherichia coliin Cameroon

New Delhi Metallo-β-Lactamase 4–producing<i>Escherichia coli</i>in Cameroon

Role of moxifloxacin for the treatment of commmunity-acquired complicated intra-abdominal infections in Taiwan

Complicated intra-abdominal infections (cIAIs) are common yet serious infections that can potentially lead to substantial morbidity and morbidity. As an essential adjunct to source control, the goals of antimicrobial therapy are to promote patient recovery, reduce recurrence risk, and prevent antimicrobial resistance. The current international guidelines on the empirical treatment of community-acquired complicated IAIs were published by the Infectious Diseases Society of America (IDSA) and Surgical Infections Society (SIS) in 2010. These guidelines all recommend the use of a fluoroquinolone (ciprofloxacin or levofloxacin) plus metronidazole for mild-to-moderate- and high-severity cases. Moxifloxacin monotherapy is recommended by the current IDSA/SIS guidelines for the treatment of mild-to-moderate complicated IAIs. Moxifloxacin has demonstrated a broad spectrum coverage of both aerobic and anaerobic pathogens, good tissue penetration into the gastrointestinal tract, and a good tolerability profile. Clinical data have demonstrated that moxifloxacin is at least as effective as other standard therapeutic regimens recommended by current clinical guidelines. Due to the high rates of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and fluoroquinolone-resistant Enterobacteriaceae among isolates causing community-acquired IAIs in Asia, any fluoroquinolones (including moxifloxacin) are not recommended as drugs of choice for the empirical treatment of community-acquired IAIs, particularly in countries (China, India, Thailand, and Vietnam) with fluoroquinolone resistance rates among Escherichia coli isolates of >20%. Given the low rates of fluoroquinolone-resistant (<20%) and extended-spectrum β-lactamase (ESBL)-producing (<10%) Enterobacteriaceae isolates associated community-acquired IAIs in Taiwan, it appears that moxifloxacin is considered an appropriate first-line therapy for patients with community-acquired complicated IAIs in this country.

High prevalence of blaCTX–M in Enterobacteriaceae isolates from the Kingdom of Bahrain

Objective To determine the molecular epidemiology of extended-spectrum β-lactamase (ESBL) by testing a cohort of clinical ESBL-producing bacterial isolates that were isolated in the Kingdom of Bahrain. Methods ESBL producing Enterobacteriaceae isolates (based on phenotypic tests) were collected from Microbiology Laboratory of the Salmaniya Medical Complex, Bahrain between January-June 2006. Antibiotic susceptibility to a panel of antibiotics was performed and bla CTX-M genes were detected by multiplex PCR. Results A total of 230 isolates ( Escherichia coli, n=180; Klebsiella pneumoniae, n=50) were studied, 98% were CTX-M type. For Escherichia coli isolates, 65 (36.1%) harbored CTXM+TEM combination and 68 (37.8%) had CTX-M alone. In contrast, for Klebsiella pneumoniae isolates only 5 (10.0%) harbored the CTX-M combination, and none had CTX-M only. The bla CTX-M gene was found predominantly in urine isolates ( n=145/230; 63.0%). Sensitivity to imipenem and nitrofurantoin was 100% and 60%, respectively. CTX-M carriage was associated with the resistance to fluoroquinolones, trimethoprim-sulfamethoxazole and aminoglycosides. Conclusions Our study documentes high prevalence of CTX-M ESBL type among Escherichia coli and Klebsiella from the Kingdom of Bahrain. The apparent dissemination of CTX-M producers could represent a substantial barrier in the treatment of community-acquired infections. The use of extended-spectrum cephalosporins, quinolones, and aminoglycosides is compromised, leaving carbapenems as the therapeutic option for severe infections caused by ESBL producers.

Clinical profiles of patients colonized or infected with extended-spectrum beta-lactamase producing Enterobacteriaceae isolates: a 20 month retrospective study at a Belgian University Hospital

BackgroundDescription of the clinical pictures of patients colonized or infected by ESBL-producing Enterobacteriaceae isolates and admitted to hospital are rather scarce in Europe. However, a better delineation of the clinical patterns associated with the carriage of ESBL-producing isolates may allow healthcare providers to identify more rapidly at risk patients. This matter is of particular concern because of the growing proportion of ESBL-producing Enterobacteriaceae species isolates worldwide.MethodsWe undertook a descriptive analysis of 114 consecutive patients in whom ESBL-producing Enterobacteriaceae isolates were collected from clinical specimens over a 20-month period. Clinical data were obtained through retrospective analysis of medical record charts. Microbiological cultures were carried out by standard laboratory methods.ResultsThe proportion of ESBL-producing Enterobacteriaceae strains after exclusion of duplicate isolates was 4.5% and the incidence rate was 4.3 cases/1000 patients admitted. Healthcare-associated acquisition was important (n = 104) while community-acquisition was less frequently found (n = 10). Among the former group, two-thirds of the patients were aged over 65 years and 24% of these were living in nursing homes. Sixty-eight (65%) of the patients with healthcare-associated ESBL, were considered clinically infected. In this group, the number and severity of co-morbidities was high, particularly including diabetes mellitus and chronic renal insufficiency. Other known risk factors for ESBL colonization or infection such as prior antibiotic exposure, urinary catheter or previous hospitalisation were also often found. The four main diagnostic categories were: urinary tract infections, lower respiratory tract infections, septicaemia and intra-abdominal infections. For hospitalized patients, the median hospital length of stay was 23 days and the average mortality rate during hospitalization was 13% (Confidence Interval 95%: 7-19). Escherichia coli, by far, accounted as the most common ESBL-producing Enterobacteriaceae species (77/114; [68%]) while CTX-M-1 group was by far the most prevalent ESBL enzyme (n = 56).ConclusionIn this retrospective study, the clinical profiles of patients carrying healthcare-associated ESBL-producing Enterobacteriacae is characterized by a high prevalence rate of several major co-morbidities and potential known risk factors. Both, the length of hospital stay and overall hospital mortality rates were particularly high. A prospective case-control matched study should be designed and performed in order to control for possible inclusion bias.

Dissemination of a blaVIM-2-Carrying Integron Among Enterobacteriaceae Species in Mexico: Report from the SENTRY Antimicrobial Surveillance Program

Three VIM-2-producing Enterobacteriaceae (two Enterobacter cloacae and one Klebsiella oxytoca) isolates recovered from patients in a Mexican hospital were characterized during the SENTRY Antimicrobial Surveillance Program (2005-2007). These strains carried identical bla(VIM-2) integrons in a 450-kb plasmid. The interspecies dissemination of this bla(VIM-2)-harboring element emphasizes the potential for spread of genetic structures carrying metallo-beta-lactamases that could limit therapeutic options in this geographic region.

Dissemination of Plasmid-mediated qnr, aac(6')-Ib-cr, and qepA Genes Among 16S rRNA Methylase Producing Enterobacteriaceae in Korea

Plasmid-mediated quinolone resistance (PMQR) genes: qnr, aac(6')-Ib-cr, and qepA were investigated among 153 armA and 51 rmtB-positive transconjugants and their 204 clinical isolates of Enterobacteriaceae. Overall, qnrB4 and aac(6')-Ib-cr genes were identified in 52.3% (63 K. pneumoniae, 10 E. coli, 4 E. cloacae, and 3 E. aerogenes) and 24.8% (16 K. pneumoniae, 8 E. coli, 6 S. marcescens, 4 E. cloacae, 3 C. freundii and 1 K. oxytoca) of 153 armA-positive isolates, respectively. Four isolates of K. pneumoniae and two isolates of E. coli positive for armA co-harbored both qnrB4 and aac(6')-Ib-cr. The qepA gene was detected in 11.8% (5 E. coli and 1 K. pneumoniae) of 51 rmtB-positive clinical isolates and their transconjugants. Southern hybridization confirmed the co-localization of qepA and rmtB on a large conjugative plasmid of size between 90 to 170 kb. Inc replicon typing showed that qnrB4/6, aac(6')-Ib-cr, and qepA genes were principally disseminated by IncFIIAs, IncL/M, and IncF plasmids, respectively. This study constitutes the first report of the three known PMQR genes among the 16S rRNA methylase producing Enterobacteriaceae isolates of human origin from Korea.

High diversity of extended-spectrum -lactamases among clinical isolates of Enterobacteriaceae from Portugal

To investigate the occurrence and the diversity of Ambler class A ESBLs among Enterobacteriaceae from different Portuguese clinical settings over a 2 year period (2002-04). One hundred and nine extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae isolates from five geographically distant health institutions in Portugal were studied. ESBLs were characterized by isoelectric focussing, PCR and further sequencing. Antibiotic susceptibility testing, transfer of resistance genes and clonal diversity were determined by standard procedures. Plasmid relatedness was established by comparison of random amplified polymorphic DNA (RAPD) patterns. ESBLs were identified as TEM (46%), SHV (30%), CTX-M (22%) and GES (2%) types; TEM-24, TEM-52, SHV-12 and CTX-M-15 enzymes being the most frequently found. Inter-hospital dissemination of epidemic strains harbouring the most prevalent ESBLs was detected, including the TEM-24-producing Enterobacter aerogenes European epidemic clone. Conjugative transfer of ESBLs was achieved for 67% of isolates and epidemic plasmids containing specific bla genes were detected (bla(CTX-M-15) and bla(TEM-24)). We describe two new ESBLs, SHV-90 (A187T, G238S and E240K) and SHV-91 (P20S and E240K), and a new TEM-type enzyme conferring a phenotype resembling that of a complex mutant TEM beta-lactamase, designated as TEM-154 (M69L and R164S). The broad-spectrum beta-lactamases SHV-26, SHV-36 and TEM-110 were first observed in our country. We describe a complex ESBL epidemiology in Portugal, including widespread dissemination of known strains and plasmids coding for TEM-24 and CTX-M-15 enzymes as observed in other European countries.

Extended-spectrum β-lactamase–type SHV-12–producing Enterobacteriaceae causing septicemia in Tanzanian children: vectors for horizontal transfer of antimicrobial resistance

Septicemia caused by extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae was associated with high mortality in Tanzanian children. Conjugation experiments on the SHV-12–producing Enterobacteriaceae isolates showed that ESBL-encoding genes were transferred on large plasmids together with genes encoding resistance to aminoglycosides, resistance to ceftazidime, gentamicin, doxycycline, trimethoprim–sulfamethoxazole, and chloramphenicol.