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Infecciones bacterianas, Page 2

Incidence of blaNDM-1 gene in Escherichia coli isolates at a tertiary care referral hospital in Northeast India.

Incidence of blaNDM-1 gene in Escherichia coli isolates at a tertiary care referral hospital in Northeast India.

Indian J Med Microbiol. 2013 Jul-Sep;31(3):250-6

Authors: Bora A, Ahmed GU, Hazarika NK, Prasad KN, Shukla SK, Randhawa V, Sarma JB

Abstract
Purpose: Increasing reports on New Delhi metallo-β-lactamase-1 (NDM-1) producing Escherichia coli constitute a serious threat to global health since it is found to be highly resistant to most of the currently available antibiotics including carbapenems. This study has been performed to find out the incidence blaNDM-1 in E. coli isolates recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. Materials and Methods: A total of 270 non-duplicated E. coli isolates were recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. All isolates with reduced susceptibility to meropenem or ertapenem (diameter of zones of inhibition, ≤21 mm) were further phenotypically confirmed for carbapenemase production by modified Hodge test. All screened isolates were also subjected to the polymerase chain reaction detection of blaNDM-1 gene and additional bla genes coding for transmission electron microscopy, SHV, CTX-M, and AmpC. Results: Out of 270 E. coli isolates, 14 were screened for carbapenemase production on the basis of their reduced susceptibility to meropenem or ertapenem. All screened isolates were found to be positive for blaNDM-1 . Each of the blaNDM-1 possessing isolate was also positive for two or more additional bla genes, such as blaTEM , blaCTX-M and blaAmpC . Phylogenetic analysis showed very less variation in blaNDM-1 gene with respect to blaNDM-1 possessing E. coli isolates from other parts of India and abroad. Conclusions: Our findings highlight the incidence of blaNDM-1 in E. coli isolates with a reduced susceptibility to meropenem or ertapenem.

PMID: 23883710 [PubMed – in process]

High prevalence of the epidemic Clostridium difficile PCR ribotype 078 in Iberian free-range pigs.

High prevalence of the epidemic Clostridium difficile PCR ribotype 078 in Iberian free-range pigs.

Res Vet Sci. 2013 Jul 19;

Authors: Alvarez-Pérez S, Blanco JL, Peláez T, Astorga RJ, Harmanus C, Kuijper E, García ME

Abstract
Previous studies in intensively raised piglets have detected a high prevalence of the epidemic Clostridium difficile PCR ribotype 078. In this article we present a longitudinal survey of C. difficile colonisation in a population of Iberian pigs reared under a free-range system. A total of 160 faecal samples from 20 piglets belonging to different litters were obtained by weekly sampling. C. difficile was recovered from samples collected at different times throughout the survey from a 90% of piglets, resulting in an overall prevalence of 25.6% in the studied samples. Most positive samples (75.6%) came from ⩽15-day animals, but some piglets shed C. difficile even on day +50. All isolates were ribotype 078, harboured toxin-encoding genes and showed in vitro resistance to several fluoroquinolones. A majority of isolates (80.5%) were also high-level resistant to ertapenem, and four metronidazole heteroresistant isolates (9.8%) were detected. In conclusion, Iberian free-range pigs can be a potential reservoir of epidemic antimicrobial-resistant strains of C. difficile, showing a prevalence rate similar to that found for intensively raised animals.

PMID: 23876331 [PubMed – as supplied by publisher]

Comparison of in vitro efficacy of ertapenem, imipenem and meropenem in the infections caused by the Enterobacteriaceae strains family.

Comparison of in vitro efficacy of ertapenem, imipenem and meropenem in the infections caused by the Enterobacteriaceae strains family.

Anaesthesiol Intensive Ther. 2013 Apr-Jun;45(2):67-72

Authors: Guzek A, Tomaszewski D, Rybicki Z, Truszczyński A, Barański M, Korzeniewski K

Abstract
BACKGROUND: The members of the bacterial Enterobacteriaceae family play an important role in the aetiology of many hospital infections. Some of them are able to produce β-lactamase, an enzyme which induces the resistance of those bacteria to penicillins, cephalosporins and, in severe infections, to penicillins with β-lactamase inhibitors. In this situation, the carbapenems become the drugs of choice. The objective of this study was to analyse the in vitro efficacy of three carbapenems: ertapenem, imipenem and meropenem against bacterial species of the Enterobacteriaceae family.
METHODS: A total of 99 bacterial species (including ten bacterial species producing the ESBL mechanism), isolated between September 2011 and March 2012 from diagnostic material collected from patients of surgical clinics in the department of motoskeletal system infections and the critical care unit, hospitalised in the Military Institute of Medicine in Warsaw, were analysed. The values of MIC 50 and MIC 90 were recorded.
RESULTS: All isolated bacterial species were susceptible to meropenem. One strain of Morganella morganii was resistant to imipenem, while one strain of Enterobacter cloaceae and one strain of Klebsiella pneumoniae were resistant to ertapenem. In the Enterobacteriaceae ESBL(-) group, the values of MIC 50 were 0.006 μg mL-1 for ertapenem, 0.19 μg mL⁻¹ for imipenem, and 0.032 μg mL⁻¹ for meropenem, and the MIC 90 values were: 0.25 μg mL⁻¹, 0.5 μg mL⁻¹ and 0.125 μg mL⁻¹, respectively. In the Enterobacteriaceae ESBL(+) group, the values of MIC 50 were 0.38 μg mL⁻¹, 0.25 μg mL⁻¹, 0.064 μg mL⁻¹, and the values of MIC 90 were 0.5 μg mL⁻¹, 0.25 μg mL⁻¹ and 0.125 μg mL⁻¹, respectively.
CONCLUSIONS: All analysed carbapenems had high in vitro efficacy against both Enterobacteriaceae ESBL(-) and Enterobacteriaceae ESBL(+) bacterial species.

PMID: 23877897 [PubMed – in process]

Antibiotic rotation for febrile neutropenic patients with hematological malignancies: clinical significance of antibiotic heterogeneity.

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Antibiotic rotation for febrile neutropenic patients with hematological malignancies: clinical significance of antibiotic heterogeneity.

PLoS One. 2013;8(1):e54190

Authors: Chong Y, Shimoda S, Yakushiji H, Ito Y, Miyamoto T, Kamimura T, Shimono N, Akashi K

Abstract
BACKGROUND: Our unit adopted the single administration of cefepime as the initial treatment for febrile episodes in neutropenic patients with hematological malignancies. However, recently, cefepime-resistant gram-negative bacteremia, including those with extended-spectrum β-lactamase (ESBL)-producers, was frequently observed in these patients. Therefore, we instituted a rotation of primary antibiotics for febrile neutropenic patients in an attempt to control antibiotic resistance.
METHODS: This prospective trial was performed from August 2008 through March 2011 at our unit. After a pre-intervention period, in which cefepime was used as the initial agent for febrile neutropenia, 4 primary antibiotics, namely, piperacillin-tazobactam, ciprofloxacin, meropenem, and cefepime, were rotated at 1-month intervals over 20 months. Blood and surveillance cultures were conducted for febrile episodes, in order to assess the etiology, the resistance pattern (particularly to cefepime), and the prognosis.
RESULTS: In this trial, 219 patients were registered. A 65.9% reduction in the use of cefepime occurred after the antibiotic rotation. In the surveillance stool cultures, the detection rate of cefepime-resistant gram-negative isolates, of which ESBL-producers were predominant, declined significantly after the intervention (8.5 vs 0.9 episodes per 1000 patient days before and after intervention respectively, P<0.01). Interestingly, ESBL-related bacteremia was not detected after the initiation of the trial (1.7 vs 0.0 episodes per 1000 patient days before and after intervention respectively, P<0.01). Infection-related mortality was comparable between the 2 periods.
CONCLUSIONS: We implemented a monthly rotation of primary antibiotics for febrile neutropenic patients. An antibiotic heterogeneity strategy, mainly performed as a cycling regimen, would be useful for controlling antimicrobial resistance among patients treated for febrile neutropenia.

PMID: 23372683 [PubMed – indexed for MEDLINE]

Kinetic Features of L,D-Transpeptidase Inactivation Critical for β-Lactam Antibacterial Activity.

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Kinetic Features of L,D-Transpeptidase Inactivation Critical for β-Lactam Antibacterial Activity.

PLoS One. 2013;8(7):e67831

Authors: Triboulet S, Dubée V, Lecoq L, Bougault C, Mainardi JL, Rice LB, Ethève-Quelquejeu M, Gutmann L, Marie A, Dubost L, Hugonnet JE, Simorre JP, Arthur M

Abstract
Active-site serine D,D-transpeptidases belonging to the penicillin-binding protein family (PBPs) have been considered for a long time as essential for peptidoglycan cross-linking in all bacteria. However, bypass of the PBPs by an L,D-transpeptidase (Ldtfm) conveys high-level resistance to β-lactams of the penam class in Enterococcus faecium with a minimal inhibitory concentration (MIC) of ampicillin >2,000 µg/ml. Unexpectedly, Ldtfm does not confer resistance to β-lactams of the carbapenem class (imipenem MIC = 0.5 µg/ml) whereas cephems display residual activity (ceftriaxone MIC = 128 µg/ml). Mass spectrometry, fluorescence kinetics, and NMR chemical shift perturbation experiments were performed to explore the basis for this specificity and identify β-lactam features that are critical for efficient L,D-transpeptidase inactivation. We show that imipenem, ceftriaxone, and ampicillin acylate Ldtfm by formation of a thioester bond between the active-site cysteine and the β-lactam-ring carbonyl. However, slow acylation and slow acylenzyme hydrolysis resulted in partial Ldtfm inactivation by ampicillin and ceftriaxone. For ampicillin, Ldtfm acylation was followed by rupture of the C(5)-C(6) bond of the β-lactam ring and formation of a secondary acylenzyme prone to hydrolysis. The saturable step of the catalytic cycle was the reversible formation of a tetrahedral intermediate (oxyanion) without significant accumulation of a non-covalent complex. In agreement, a derivative of Ldtfm blocked in acylation bound ertapenem (a carbapenem), ceftriaxone, and ampicillin with similar low affinities. Thus, oxyanion and acylenzyme stabilization are both critical for rapid L,D-transpeptidase inactivation and antibacterial activity. These results pave the way for optimization of the β-lactam scaffold for L,D-transpeptidase-inactivation.

PMID: 23861815 [PubMed – in process]

Outbreak Caused by an Ertapenem-Resistant, CTX-M-15-Producing Klebsiella pneumoniae ST101 Clone Carrying an OmpK36 Porin Variant.

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Outbreak Caused by an Ertapenem-Resistant, CTX-M-15-Producing Klebsiella pneumoniae ST101 Clone Carrying an OmpK36 Porin Variant.

J Clin Microbiol. 2013 Jul 12;

Authors: Poulou A, Voulgari E, Vrioni G, Koumaki V, Xidopoulos G, Chatzipantazi V, Markou F, Tsakris A

Abstract
Although numerous studies have documented outbreaks of carbapenem-resistant Klebsiella pneumoniae (CRKP) possessing various carbapenemases, reports on outbreaks due to CRKP possessing extended-spectrum β-lactamases (ESBLs) and/or AmpCs with porin lesions are limited. We describe an outbreak caused by an ertapenem-resistant, CTX-M-15-producing K. pneumoniae clonal strain expressing an OmpK36 porin variant. From May 2012-November 2012, 37 ertapenem-resistant, phenotypically-negative for carbapenemase production K. pneumoniae isolates were recovered from 19 patients hospitalized in the intensive care unit of a Greek hospital. The isolates were either susceptible or intermediate to other carbapenems and resistant to all remaining β-lactams but cefotetan. Phenotypic and molecular analysis revealed in all isolates the presence of blaCTX-M-15 gene on a conjugative 100-kb plasmid, disruption in the expression of the ompK35 gene and the production of an Ompk36 porin variant. The index case was a patient admitted from another hospital. Active surveillance upon admission and on a weekly basis was immediately initiated; environmental samples were also periodically tested. Molecular typing showed that all clinical isolates as well as two ertapenem-resistant K. pneumoniae environmental isolates belonged to the same clonal type and were assigned to MLST sequence type ST101. As all colonized/infected patients were hospitalized in overlapping periods, cross-infection was considered as the main route for the dissemination of the outbreak strain. Despite reinforcement of infection control measures and active surveillance the outbreak lasted approximately 7 months. Identification of hidden carriers upon admission and by screening on weekly basis was found valuable for early recognition and subsequent successful management of the outbreak.

PMID: 23850951 [PubMed – as supplied by publisher]

A Combined Disk Test for Direct Differentiation of Carbapenemase-Producing Enterobacteriacae in Surveillance Rectal Swabs.

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A Combined Disk Test for Direct Differentiation of Carbapenemase-Producing Enterobacteriacae in Surveillance Rectal Swabs.

J Clin Microbiol. 2013 Jul 10;

Authors: Pournaras S, Zarkotou O, Poulou A, Kristo I, Vrioni G, Themeli-Digalaki K, Tsakris A

Abstract
Carbapenemase-producing Enterobacteriaceae (CPE) are rapidly spreading worldwide. Early detection of CPE fecal carriers is essential for effective infection control. We evaluated the performance of a combined meropenem disk test (CDT) for rapidly differentiating CPE, directly from rectal swabs. The screening method was applied in 189 rectal swabs from hospitalized patients at high-risk. Swabs were suspended in 1 ml saline and cultured for confluent growth onto a MacConkey agar plate with meropenem disk (MER) alone, MER plus phenyl boronic acid (PBA), MER plus EDTA and MER plus PBA and EDTA. Inhibition zone ≤25 mm around MER alone indicated carriage of carbapenem-resistant organism. Furthermore, ≥5 mm difference in the inhibition zone between MER without and with inhibitors (PBA, EDTA or both) was considered positive result for detectng KPC, metallo-β-lactamase (MBL) or both carbapenemases, respectively. For comparison, rectal suspensions were tested using MacConkey plates with ertapenem disks (MacERT) and PCR (PCR-S) for carbapenemase genes. Of the 189 samples, 97 were genotypically confirmed CPE-positive by any of the three protocols tested. CDT, MacERT and PCR-S exhibited sensitivities 94.8%, 96.9% and 94.8% and specificities 100%, 98.9% and 100%, respectively, for detecting CPE-positive swabs. Moreover, CDT differentiated correctly the production of KPC, MBL or both carbapenemases in 78 of the 97 (80.4 %) CPE-positive rectal swabs. Our results demonstrate that CDT may provide a simple and inexpensive method to detect and differentiate the carbapenemase type within a single day, without requiring further testing and additional delay, supporting the timely implementation of infection control measures.

PMID: 23843486 [PubMed – as supplied by publisher]

Etiology, Extended-spectrum β-lactamase Rates and Antimicrobial Susceptibility of Gram-negative Bacilli Causing Intra-abdominal Infections in Patients in General Pediatric and Pediatric Intensive Care Units-Global Data From The Study for Monitoring Antimicrobial Resistance Trends 2008 to 2010.

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Etiology, Extended-spectrum β-lactamase Rates and Antimicrobial Susceptibility of Gram-negative Bacilli Causing Intra-abdominal Infections in Patients in General Pediatric and Pediatric Intensive Care Units-Global Data From The Study for Monitoring Antimicrobial Resistance Trends 2008 to 2010.

Pediatr Infect Dis J. 2013 Jun;32(6):636-40

Authors: Badal RE, Bouchillon SK, Lob SH, Hackel MA, Hawser SP, Hoban DJ

Abstract
BACKGROUND: Antimicrobial resistance has been increasing for several years and is often higher in intensive care units (ICUs) than in other facilities. The spread of extended-spectrum β-lactamases (ESBLs) in particular has profoundly impacted antimicrobial efficacy and usage. The Study for Monitoring Antimicrobial Resistance Trends has monitored the in vitro activity of ertapenem and several comparators against aerobic gram-negative bacteria from intra-abdominal infections (IAIs) for many years. This report summarizes susceptibility levels and epidemiology for key IAI pathogens cultured from general pediatric medical wards and pediatric ICUs globally.
METHODS: 1248 gram-negative bacteria were collected from pediatric IAIs by 113 labs in 40 countries from 2008 to 2010. Susceptibility was determined by Clinical and Laboratory Standards Institute broth microdilution. Susceptibility rates (%S) were determined for species with ≥10 isolates.
RESULTS: Sixty-two percent of isolates came from general pediatric wards and 38% from pediatric ICUs. The overall ESBL-positive rate was 11.0% for Escherichia coli and 38.9% for Klebsiella pneumoniae; the ESBL-positive rate for E. coli was twice as high in ICU as non-ICU. Most study drugs inhibited >90% of ESBL-negative isolates, but only the carbapenems inhibited >90% of ESBL-positive E. coli and only imipenem inhibited >90% of ESBL-positive K. pneumoniae.
CONCLUSIONS: Amikacin, imipenem and ertapenem were the most active against gram-negative bacteria from pediatric IAIs, followed closely by the fluoroquinolones and cefepime. Other cephalosporins were often <90% active. ESBL rates were 38.9% for K. pneumoniae and 11.0% for E. coli. Therapy for pediatric IAIs should take into consideration local ESBL rates because only carbapenems inhibited most of these pathogens.

PMID: 23838732 [PubMed – in process]