Epidemic and Endemic Spread ofKlebsiella pneumoniaeProducing SHV-5 Beta-Lactamase in Dubrava University Hospital, Zagreb, Croatia

Identification and molecular characterization of Escherichia coli blaSHV genes in a Chinese teaching hospital

Escherichia coli (E. coli) commonly reside in human intestine and most E. coli strains are harmless, but some serotypes cause serious food poisoning. This study identified and molecularly characterized bla_SHV genes from 490 E. coli strains with multi-drug resistance in a hospital population. PCR and molecular cloning and southern blot were performed to assess functions and localizations of this resistant E. coli gene and the pulsed-field gel electrophoresis (PFGE) was utilized to demonstrate the clonal relatedness of the positive E. coli strains. The data showed that 4 of these 490 E. coli strains (4/499, 0.8%) carried bla_SHV genes that included EC D2485 (bla_SHV-5), EC D2487 (bla_SHV-5), EC D2684 (bla_SHV-11) and EC D2616 (bla_SHV-195, a novel bla_SHV). Analysis of bla_SHV open-reading frame showed that bla_SHV-5 had a high hydrolysis activity to the broad-spectrum penicillin (ampicillin or piperacillin), ceftazidime, ceftriaxone, cefotaxime and aztreonam. bla_SHV-195 and bla_SHV-11 had similar resistant characteristics with high hydrolysis activities to ampicillin and piperacillin, but low activities to cephalosporins. Moreover, the two bla_SHV-5 genes were located on a transferable plasmid (23kb), whereas the other two bla_SHV variants (bla_SHV-11 and bla_SHV-195) seemed to be located in the chromosomal material. Both EC D2485 and EC D2487 clones isolated in 2010 had the same DNA finger printing profile and they might be the siblings of clonal dissemination. The data from the current study suggest that the novel bla_SHV and clonal dissemination may be developed, although bla_SHV genes were infrequently identified in this hospital population. The results of the work demonstrate the necessity for molecular surveillance in tracking bla_SHV-producing strains in large teaching hospital settings and emphasize the need for epidemiological monitoring.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp.

Characterization of the extended-spectrum β-lactamases and determination of the virulence factors of uropathogenic Escherichia coli strains isolated from children

BACKGROUND AND AIM

The aim of the study was to characterize ESBL-producing uropathogenic Escherichia coli (UPEC) strains isolated in children. That included the investigation of virulence factors and the analysis of the types of β-lactamases at the molecular genetic level.

MATERIAL AND METHODS

During the 2-year study period, 77 ESBL-producing E. coli strains were recovered from urine samples of febrile children with significant bacteriuria hospitalized at one Croatian hospital. Susceptibility of isolates to bactericidal serum activity was tested by Shiller and Hatch method, while adhesin expression was determined by agglutination methods. Characterization of ESBLs was performed by PCR with specific primers for ESBLs and by sequencing of bla (ESBL) genes. Genotyping of the E. coli isolates was performed by pulsed-field gel electrophoresis (PFGE).

RESULTS

Twenty-seven (35.1 %) and 50 (64.9 %) ESBL-producing UPEC strains were isolated in neonates and infants, respectively. Of 70 strains investigated for the presence of virulence factors, adhesins were detected in 48.6 % strains (8.6 % in the neonate and 40 % in the infants group) giving a statistically significant difference in adhesin expression between the two groups (p < 0.01). Hemolysin was produced by 84.3 %, whereas 70 % of strains were serum-resistant. The bla (TEM) gene was detected in 22 (28 %) and bla (SHV) gene in 57 strains (74 %), whereas bla (CTX-M) gene was detected in only two isolates (2.5%). In ten isolates, bla (TEM) and bla (SHV) were simultaneously detected. Sequencing of bla (SHV) genes revealed that SHV-5 β-lactamase was by far the most prevalent and was found in 51 strains (66 %). The strains were clonally related as demonstrated by PFGE and assigned into ten clusters.

CONCLUSIONS

Infection control measures should be employed and the consumption of expanded-spectrum cephalosporins in the hospital should be restricted.

Antibiotic susceptibility profiles and first report of TEM extended-spectrum β-lactamase in Pseudomonas fluorescens from coastal waters of the Kaštela Bay, Croatia

The aim of this study was to investigate the antibiotic susceptibility profiles and the presence of extended-spectrum-β-lactamases (ESBLs) in Pseudomonas fluorescens isolates from coastal waters of the Kaštela Bay, Croatia. Twenty-two water samples were collected during 2009. Isolates were tested for susceptibilities to 13 antibiotics by Etest. ESBL production was confirmed by double-disk synergy test carried out on Mueller-Hinton agar plates containing efflux pump inhibitor Phe-Arg-β-naphthylamide dihydrochloride. PCR and DNA sequencing analysis were used to identify ESBL-encoding genes. The transferability of cephalosporin resistance was tested by conjugation experiments. Genetic relatedness of ESBL-producing isolates was determined by random amplified polymorphic DNA (RAPD) analysis. Out of 185 P. fluorescens isolates recovered, 70 (37.8%) demonstrated multiresistance phenotype with highest rates of resistance to tetracycline (61.6%), aztreonam (31.9%), meropenem (17.3%), ceftazidime (15.1%) and cefotaxime (12.4%). Ten (5.4%) isolates were identified as ESBL producers. All isolates carried chromosomally located bla (TEM-116) gene. RAPD analysis identified four different genotypes. Here, we demonstrated a baseline profiles of antimicrobial resistance of P. fluorescens from coastal waters of the Kaštela Bay, Croatia. To our knowledge, this is the first report of the presence of TEM-type ESBL in P. fluorescens, indicating this bacterium as a reservoir of antibiotic resistance genes with clinical relevance.

Clonal spread of CTX-M-15-producing Klebsiella pneumoniae in a Croatian hospital

This study was conducted to detect and analyse the presence of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae associated with a nosocomial outbreak at a Croatian hospital. During 2007, 162 K. pneumoniae isolates with reduced susceptibility to third-generation cephalosporins were collected from various hospital units and patient specimens. Most of the strains were isolated from urine (61 %), followed by blood cultures (13 %), wound swabs (13 %), tracheal aspirates (5 %), intra-abdominal abscess aspirates (4 %), intravascular catheters (3 %) and cerebrospinal fluid (1 %). Medical wards were the most important source of the isolates (46 %); 21 % of the isolates originated from surgical intensive-care units. All patients had infections acquired during their stay in hospital. No community-acquired infections were reported. Sixty of these isolates were chosen for further analysis. A double-disc synergy test (DDST) was used to detect ESBLs. MICs were determined by the broth microdilution method according to CLSI guidelines. The transferability of ceftazidime resistance was tested by conjugation (broth mating method). PCR was used to detect alleles encoding ESBL enzymes. Plasmids encoding ESBLs were extracted with the Macherey Nagel Mini kit according to the manufacturer's recommendations. The genotypes of the strains were compared by analysis of banding patterns generated by PFGE of XbaI-digested genomic DNA. ESBLs were found by DDST in all isolates. All strains were resistant to cefuroxime, ceftazidime, cefotaxime, ceftriaxone, aztreonam, piperacillin/tazobactam and ciprofloxacin. There was variable susceptibility/resistance to cefepime and gentamicin. No resistance to ceftazidime/clavulanate and carbapenems was observed. Only six strains transferred resistance to an Escherichia coli recipient strain, with low frequency. All isolates yielded an amplicon of 545 bp with consensus MA primers. Multiplex PCR was positive for group 1 CTX-M β-lactamases. Sequencing of selected amplicons revealed the presence of bla CTX-M-15, with coding regions containing identical nucleotide sequences. Similarly to isolates from India, our isolates contained the ISEcpI insertion sequence located upstream of the bla CTX-M-15 gene, which has recently been demonstrated to mobilize 3′-adjacent genes to transfer between DNA replicons. The isolates contained a large plasmid of approximately 150 kb. The isolates were assigned to five clusters (>85 % similarity), which contained subclusters. The results of this work provided insights into the molecular epidemiology of the spread of ESBLs in K. pneumoniae involved in an outbreak at a Croatian hospital. The hospital antibiotic policy resulted in ceftriaxone being the most heavily prescribed third-generation cephalosporin, which might be expected to select for cefotaximases such as CTX-M-15.

Molecular epidemiology of multidrug resistant extended spectrum beta-lactamase producing Klebsiella pneumoniae at a Jamaican hospital, 2000-2004

BACKGROUND

The accurate identification of a pathogen beyond the species level is critical in epidemiological studies and investigations of nosocomial outbreaks of infection. The clonal relatedness of 66 multidrug resistant (MDR) strains of extended spectrum beta-lactamase (ESBL) producing K. pneumoniae isolated from clinical specimens from hospitalized patients at a Jamaican hospital during a 5 year period were determined by pulsed field gel electrophoresis (PFGE).

RESULTS

A total 10 different ESBL producing K. pneumoniae genotypes designated Clones I-X were found. The most frequently occurring strains belonged to Clones I (21/66, 32%), II (15/66, 26%), III (13/66, 20%) and IV (8/66, 12%) which accounted for 86% (57/66) of ESBL producing K. pneumoniae strains over the 5 year period. The remaining 9 (14%) cases of ESBL producing K. pneumoniae were due to strains of Clones V-X. The 4 predominant clones persisted for several years in the hospital.

CONCLUSIONS

The clonal and temporal distribution of the MDR ESBL producing K. pneumoniae strains among clinical service areas did not suggest outbreaks of the organism during the period of study. Instead the molecular epidemiology of ESBL producing K. pneumoniae at this hospital was more representative of an endemic persistence of clones of the organism with limited dissemination from patient to patient. Further studies to investigate the factors which determine the emergence and persistence of MDR ESBL producing K. pneumoniae in Jamaican hospitals and their impact on clinical and economic outcomes at such institutions would be useful.

Sensitivity and specificity of various beta-lactam antibiotics and phenotypical methods for detection of TEM, SHV and CTX-M extended-spectrum beta-lactamases

The aim of this study was to compare the sensitivity and specificity of six different beta-lactam antibiotics using five phenotypical tests for detection of extended spectrum beta-lactamases (ESBLs) based on synergism of beta-lactam antibiotics and clavulanate. Experiments were performed on a set of 80 Klebsiella pneumoniae strains and 105 Escherichia coli strains with previously characterized ESBLs (SHV, TEM and CTX-M). ESBLs were detected by five different phenotypical methods: MIC (minimum inhibitory concentration) determination of beta-lactam antibiotics with and without clavulanate, double-disk synergy test (DDST), inhibitor-potentiated disk-diffusion test (IPDDT), CLSI-Clinical and Laboratory Standard Institution (former NCCLS) combined-disk-test, and modified MAST-disk-diffusion test (MAST-DD-test). Seven antibiotics were tested as indicators of ESBL production: ceftazidime, cefotaxime, ceftriaxone, aztreonam, ceftibuten, cefpodoxime and cefepime. Ceftazidime and aztreonam were the best indicators for SHV-5, SHV-12 and TEM beta-lactamases whereas cefotaxime and ceftriaxone were the most sensitive in detection of SHV-2 and CTX-M beta-lactamases in DDST, IPDDT and CLSI test. MIC determination of beta-lactam antibiotics with and without clavulanate was the most sensitive method. DDST was the least sensitive test. Double-disk synergy test, which is the most frequently used test for detection of ESBLs in routine laboratories, was the least sensitive independently of the indicator antibiotic. Since MIC determination is a very laborious and time consuming method, we would recommend the NCCLS combined disk test or IPDD test for detection of ESBLs in routine laboratories with 5 mm zone augmentation breakpoint.