Effects of overexpression of carbapenem OXA-48 on drug resistance,adaptability of bacterial strain and Toll-like receptor signaling pathway of host cell / 中国生物制品学杂志

@#Objective To investigate the effects of overexpression of OXA-48 on drug resistance,adaptability of bacterial strain and Toll-like receptor(TLR)signaling pathway of host cells. Methods The recombinant plasmid pET32a(+)-OXA-48was transformed into E.coli BL21(DE3),and the recombinant strain pET32a(+)-OXA-48-BL21(DE3)was identified by colony PCR and sequencing. Taking A_(600)(0. 3,0. 5 and 0. 7),IPTG final concentration(0. 4,0. 6 and 0. 8mmol/L)and induction time(2,4 and 6 h)as variables and mRNA transcription level as response value,an orthogonal experiment with three factors and three levels was designed to optimize the induced expression conditions of the plasmid. The drug resistance of recombinant strain pET32a(+)-OXA-48-BL21(DE3)to Imipenem(IPM),Meropenem(MEM),Ceftriaxone(CRO)and Cefepime(FEP)was detected by disk diffusion method;The adaptability was detected by biofilm formation test and serum resistance test. Mouse alveolar macrophages(MH-S)were infected with pET32a(+)-OXA-48-BL21(DE3),pET32a(+)-BL21(DE3)and E.coli BL21(DE3)strains,respectively. The mRNA transcription levels of TLR2,TLR4 and NF-кB(p65)genes were detected by qRT-PCR method,and the expressions of Interleukin-6(IL-6),IL-10,tumor necrosis factor-α(TNF-α)and transforming growth factor-β(TGF-β)were detected by ELISA. Results The recombinant strain pET32a(+)-OXA-48-BL21(DE3)was constructed correctly as identified by colony PCR and sequencing. The optimum induction conditions were as follows:A_(600)of 0. 3,IPTG final concentration of 0. 6 mmol/L and induction time of 2 h. Compared with pET32a(+)-BL21(DE3)strain,the resistance of recombinant strain pET32a(+)-OXA-48-BL21(DE3)to IPM,MEM,CRO and FEP significantly decreased(t = 7. 14～22. 32,P < 0. 05),the biofilm formed significantly increased(t = 15. 69,P < 0. 05),and the survival rate in serum significantly increased(t = 10. 60,P < 0. 05);The mRNA transcription level of TLR2 gene in MH-S cells infected with pET32a(+)-OXA-48-BL21(DE3)significantly increased 24 h after infection(t = 5. 77,P < 0. 05),while the mRNA transcription level of TLR4 and NF-кB(p65)genes(t = 3. 71～10. 06,P < 0. 05)and the expression level of IL-6 significantly increased 12 and 24 h after infection. Compared with the normal group,the expression of IL-6and TNF-α in MH-S cells infected with pET32a(+)-OXA-48-BL21(DE3)increased significantly at 6,12 and 24 h after infection(t = 7. 90 ～ 13. 44 and 5. 40～6. 32 respectively,each P < 0. 01),while the expression of IL-10 decreased significantly(t = 3. 15～4. 08,each P < 0. 05). There was no significant difference in the expression of TGF-β(t = 0. 013～1. 41,each P > 0. 05). The expression of IL-6 was significantly higher than that in pET32a(+)-BL21(DE3)group at 12 and 24 h after infection(t = 2. 92 and 3. 79 respectively,each P < 0.05) Conclusion Overexpression of OXA-48 can reduce bacterial drug resistance,improve bacterial adaptability and the transcription level of factors related to TLR signaling pathway in host cells,and affect the expression level of downstream cytokines in host cells.

Caracterización fenotípica y molecular de cepas de Klebsiella pneumoniae productores de carbapenemasas tipo OXA-48 circulantes en Chile

Introducción: La aparición y diseminación de Enterobacterales resistentes a carbapenémicos ha generado un gran impacto en las infecciones asociadas a la atención de salud en el mundo. Recientemente, en Chile se detectó un brote por Klebsiella pneumoniae productora de carbapenemasas tipo oxacilinasas (OXA) de la subfamilia tipo OXA-48, reportándose los primeros casos en pacientes hospitalizados mayoritariamente en la zona norte del país. Objetivo: Determinar los perfiles fenotípicos, genotípicos y de susceptibilidad antimicrobiana de 16 cepas referidas durante mayo del año 2021 desde las regiones de Antofagasta y Metropolitana al Laboratorio de Referencia del Instituto de Salud Pública. Metodología: Las cepas provenientes de muestras clínicas fueron analizadas mediante técnicas tradicionales (Kirby-Bauer y epsilometría) y automatizadas, además de técnicas colorimétricas, inmunocromatográficas y moleculares (RPC y PFGE). Resultados: Se detectó la presencia de los genes blaoxa-48 y blaoxa-232 con una resistencia inusual, tanto a carbapenémicos (ertapenem, imipenem y meropenem) como a cefalosporinas (cefepime, cefotaxima y ceftazidima), además de piperacilina/tazobactam y temocilina. Se detectaron dos subtipos por PFGE, siendo predominante el clon CL-Kpn-Spe-329 (93,8%) con dos mecanismos de resistencia identificados: carbapenemasa y β-lactamasa de espectro extendido (BLEE). Conclusión: Ante esta alerta epidemiológica es necesario unificar criterios existentes en la red asistencial nacional para la oportuna detección, vigilancia y control de posibles brotes de cepas productores de oxacilinasa tipo OXA-48.

Background: The appearance and spread of carbapenems-resistant Enterobacterales have generated a major impact on health care-associated infections worldwide. Recently, a Klebsiella pneumoniae outbreak expressing OXA-48 like-carbapenemases was detected in Chile, the first reported cases corresponded to hospitalized patients mainly from northern Chile. Aim: To characterize the phenotypic and genotypic profiles of antimicrobial susceptibility of 16 clinical isolates referred during May 2021 from Antofagasta and Metropolitan regions to the Reference Laboratory of Instituto de Salud Publica. Methods: Antimicrobial susceptibility of all strains was analyzed using traditional (Kirby-Bauer and epsilometry) and automated methods, and complemented with colorimetric, immunochromatographic and molecular (PCR and PFGE) techniques. Results: As a result of the genetic characterization, blaoxa-48 and blaoxa-232 genes were detected, showing the isolates an unusual resistance profile to both carbapenems (ertapenem, imipenem, and meropenem) and cephalosporins (cefepime, cefotaxime, and ceftazidine), as well as piperacillin/ tazobactam and temocillin. Two subtypes were detected by PFGE, with a predominant clone CL-Kpn-Spe-329 (93.8%), with two resistance mechanisms identified: carbapenemase and extended-spectrum β-lactamase (ESBL). Conclusion: Due to this epidemiological alert, it is essential the establishment of national guidelines for early detection, surveillance, and control of future outbreaks of OXA-48 like carbapenemases isolates.

Susceptibility testing for aztreonam plus ceftazidime/avibactam combination: A general guidance for clinical microbiology laboratories in India

Metallo beta-lactamases-producing Gram-negative infection is often challenging and there is no defined treatment option. In recent years, the combination of aztreonam with ceftazidime-avibactam has gained much clinical attention mainly for MBL-producing Enterobacterales, while MBL-producing P. aeruginosa and A. baumannii are likely to be resistant. A consensus susceptibility testing method for this triple combination has yet to be recommended. Various methods such as broth disk elution, disk stacking, gradient strip stacking, and strip crossing have been proposed for testing this combination. Among them, broth disk elution and strip based testing methods showed good correlation with the broth micro-dilution method.

Primer reporte de Enterobacterales dobles productores de carbapenemasas en hospitales de Paraguay. Año 2021

RESUMEN Las carbapenemasas se encuentran ampliamente distribuidas en nuestro país, tanto en bacilos gramnegativos fermentadores como no fermentadores. Durante 2021, se ha reportado incremento de cepas con estas enzimas. Con el objetivo de evaluar la doble producción de carbapenemasas en Enterobacterales y comunicar su circulación, fue puesta a punto una PCR convencional múltiple. Estudio retrospectivo en 128 aislamientos provenientes de 20 centros colaboradores de la Red Nacional de Vigilancia de la RAM (Capital, Central e interior del país), remitidos al LCSP entre febrero y setiembre de 2021, para confirmación y genotipificación de carbapenemasas. Se realizaron pruebas fenotípicas y colorimétricas con sustratos específicos, y pruebas genotípicas (PCR convencional múltiple) para la detección simultánea de varios genes de resistencia (bla NDM, bla KPC, bla OXA-48-like, bla IMP y bla VIM). De los 128 aislamientos estudiados, 107 correspondieron a Klebsiella pneumoniae, 14 a Enterobacter cloacae complex, entre otros; aislados en mayor frecuencia de muestras de orina (30%), respiratorias (30%), sangre y catéter (24%). Los genes de resistencia a los carbapenemes detectados fueron: bla NDM (77,3%), bla KPC (17,2%); siendo confirmada la doble producción de carbapenemasas en 7 aislamientos (5,5%) provenientes de 4 centros diferentes de la capital de país y uno de Central; 6 de ellas (K. pneumoniae) con bla NDM+bla KPC y 1 (E. cloacae complex) con bla NDM+bla OXA-48-like; confirmando circulación de Enterobacterales dobles productores de carbapenemasas en el país (KPC+NDM y OXA+NDM); hallazgos que obligan a proveer de capacidades de detección, de manera a que se puedan tomar medidas oportunas y eficaces de contención y control.

ABSTRACT Carbapenemases are widely distributed in our country, both in fermenting and non-fermenting gram-negative bacilli. During 2021, an increase in strains with these enzymes has been reported. In order to evaluate the double production of carbapenemases in Enterobacterales and communicate their circulation, a multiple conventional PCR was set up. Retrospective study carried out in 128 isolates from 20 collaborating centers of the National AMR Surveillance Network (Capital, Central and interior of the country), sent to the LCSP between February and September 2021, for confirmation and genotyping of carbapenemases. Phenotypic and colorimetric tests were performed with specific substrates, as well as genotypic tests (multiple conventional PCR) for the simultaneous detection of several resistance genes (blaNDM, blaKPC, blaOXA-48-like, blaIMP and blaVIM). Of the 128 isolates studied, 107 corresponded to Klebsiella pneumoniae, 14 to Enterobacter cloacae complex, among others; isolated in higher frequency from urine (30%), respiratory (30%), blood and catheter (24%) samples. The genes for resistance to carbapenems detected were: blaNDM (77.3%), blaKPC (17.2%); the double production of carbapenemases was confirmed in 7 isolates (5.5%) from 4 different centers in the capital of the country and one in Central; 6 of them (K. pneumoniae) with blaNDM + blaKPC and 1 (E. cloacae complex) with blaNDM + blaOXA-48-like; confirming circulation of double Enterobacterales producers of carbapenemases in the country (KPC + NDM and OXA + NDM); findings that require the provision of detection capabilities, so that timely and effective containment and control measures can be taken.

First Clinical Cases of OXA-48-Producing Klebsiella pneumoniae in Peru / Primeros casos clínicos de infecciones por Klebsiella pneumoniae productora de OXA-48 en Perú

Background: Carbapenemase-producing Enterobacteriaceae(CPE) represents a global public health concern and systemic infectionsassociatedwithOXA-48 carbapenemase are increasingly being reported in Latin America. Here, we present the first 2 cases of systemic infections by OXA-48-ProducingKlebsiellapneumoniaein Peru. A favorable clinical response was observed after targeted treatment with colistin as a backbone.

Introducción: Las enterobacterias productoras de carbapenemasas (EPC) representan un problema de salud pública y cada vez hay más reportes de infecciones sistémicas asociadas con la carbapenemasa OXA-48 en America Latina. Presentamos los primeros 2 casos de infecciones sistémicas por Klebsiella pneumoniae productora de OXA-48 en Perú. Se observó una respuesta clínica favorable luego del tratamiento dirigido con colistina como base.

Prevalence of carbapenemase production in Pseudomonas aeruginosa isolates causing clinical infections in Lagos University Teaching Hospital, Nigeria

Background: Pseudomonas aeruginosa has been highly associated with carbapenem resistance in which carbapenemases has been suggested to be a major contributory factor. Hence the objective of this study was to phenotypically detect KPC-type carbapenemase, metallo-ß-lactamase and OXA-48 carbapenemase production in clinical isolates of P. aeruginosa in Lagos University Teaching Hospital (LUTH), Nigeria Methodology: One hundred and seventy-one P. aeruginosa isolates consecutively recovered from clinical specimens of patients with infections at the Medical Microbiology and Parasitology laboratory of the hospital were identified using MicrobactTM 24E kit. Preliminary screening for carbapenem resistance was determined by the disc diffusion method on Mueller-Hinton agar using single discs of meropenem and imipenem. Phenotypic detection of carbapenemase production among carbapenem-resistant isolates was performed by the combination disc test of meropenem-phenylboronic acid (MRPBO) and meropenem-dipicolinic acid (MRPDP) as recommended by EUCAST 2013 guideline. Results: Out of the 171 P. aeruginosa isolates, 35 (20.5%) were carbapenem non-susceptible (resistant) while carbapenemase production was detected in 27 (77.1%) of these carbapenem resistant isolates, and no enzyme was detected in 8 (22.9%). Of the 27 carbapenemase producing isolates, 22 (81.5%) produced MBL, 1 (3.7%) produced KPC, while 4 (14.8%) produced both KPC and MBL enzymes. Conclusion: This study revealed that carbapenem resistance among P. aeruginosa clinical isolates in our institution is gradually increasing. The mechanism for this rise is associated with carbapenemases, with MBL being the major carbapenemase involved. There is the need to ensure strict compliance with the LUTH infection control guidelines in order to check the rising incidence of infection caused by carbapenem resistant P. aeruginosa

Rapid Identification of OXA-48-like, KPC, NDM, and VIM Carbapenemase-Producing Enterobacteriaceae From Culture: Evaluation of the RESIST-4 O.K.N.V. Multiplex Lateral Flow Assay

There is an urgent need for accurate and rapid diagnostic assays capable of identifying carbapenemase-producing Enterobacteriaceae (CPE). We assessed the performance of the RESIST-4 O.K.N.V. (OKNV) assay (Coris BioConcept, Gembloux, Belgium) for the identification of oxacillinase (OXA)-48-like-, Klebsiella pneumoniae carbapenemase (KPC)-, New Delhi metallo-β-lactamase (NDM)-, and Verona integron-encoded metallo-β-lactamase (VIM)-producing Enterobacteriaceae grown on sheep blood agar (SBA) and the CHROMagar KPC medium. Sixty-five carbapenem-resistant Enterobacteriaceae (CRE) isolates with characterized carbapenemase content were used to evaluate the OKNV assay. The assay correctly identified all 30 isolates that produced one of the four targeted carbapenemase families. Additionally, it correctly identified 15 isolates that co-produced KPC and NDM, VIM and NDM or OXA-48-like and NDM, but failed to identify an NDM-1 and OXA-232 co-producing Klebsiella pneumoniae isolate. All 16 non-carbapenemase-producing CRE and four CPE isolates exhibited negative results, and no cross-reaction was observed. Overall, the sensitivity and specificity of the assay were 97.8% and 100%, respectively. The OKNV assay is an accurate and rapid assay for identifying OXA-48-like, KPC, NDM, and VIM carbapenemases produced by Enterobacteriaceae isolates cultured on both SBA and the CHROMagar KPC media in the clinical microbiology laboratory.

Will ceftazidime/avibactam plus aztreonam be effective for NDM and OXA-48-Like producing organisms: Lessons learnt from In vitro study

Introduction: Carbapenem resistance (CR) in Klebsiella pneumoniae is mainly mediated by bla NDM and bla OXA-48 carbapenemases. Newer Food and Drug Administration-approved antimicrobial ceftazidime/avibactam (C/A) has a potent activity against bla OXA-48-like producers. However, its activity is limited in organisms co-producing bla NDM and bla OXA-48-like. Addition of aztreonam (ATM) to C/A potentially expands the spectrum of coverage for carbapenemase co-producers. With this, we aimed to determine the synergistic activity of combination of C/A plus ATM against bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48-like producing CR Klebsiella pneumoniae (CRKp). Materials and Methods: A total of 12 isolates of CRKp-harbouring genes encoding bla NDM and bla OXA-48-like were tested. Minimum inhibitory concentrations (MICs) were determined for several antimicrobial agents, including C/A (0.5�?g/ml) by broth microdilution method. Checkerboard assay was performed for the combination of C/A plus ATM at varying concentrations. Fold differences in the MIC of C/A with and without addition of ATM were determined to infer synergistic effects. Results: MIC of C/A and ATM ranged from 0.5 to >8 ?g/ml and 64 to 2048 ?g/ml, respectively. Two isolates were susceptible to C/A with MIC of 0.5 and 1 ?g/ml, while others were resistant with MIC of >8 ?g/ml. Synergistic effects of >8-fold MIC difference in C/A MIC were noted with addition of ATM at 4 ?g/ml. This was observed for all CRKp with profiles of bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48-like genes, which was a promising effect. Notably, all five of the colistin-resistant CRKp were inhibited with >8-fold MIC difference in the combination of C/A plus ATM at 4 ?g/ml. Conclusion: With the increasing burden of CRKp, the use of C/A with ATM combination seems to be very promising, especially for bla NDM, bla OXA-48-like and co-producers of bla NDM + bla OXA-48like carbapenemases.

Colistin-sparing approaches with newer antimicrobials to treat carbapenem-resistant organisms: Current evidence and future prospects

Antimicrobial resistance is on the rise across the globe. Increasing incidence of infections due to carbapenem resistance organisms is becoming difficult to treat, due to the limited availability of therapeutic agents. Very few agents such as colistin, fosfomycin, tigecycline and minocycline are widely used, despite its toxicity. However, with the availability of novel antimicrobials, beta-lactam/beta-lactamase inhibitor-based and non-beta-lactam-based agents could be of great relief. This review covers three important aspects which include (i) current management of carbapenem-resistant infections, (ii) determination of specific types of carbapenemases produced by multidrug-resistant and extensively drug-resistant Gram-negative pathogens and (iii) the currently available novel beta-lactam/beta-lactamase inhibitors and non-beta-lactam-based agents' laboratory findings, clinical outcome and implications.

Molecular detection of Enterobacteriaceae isolates producing blaOXA-48 and blaOXA-181 genes: A single centre study

@#Introduction: OXA-48, a carbapenem-hydrolysing class D β-lactamase, and its variant, OXA-181, are increasingly reported worldwide. This study aimed to describe the prevalence and distribution of OXA-48 and OXA-181 carbapenem-resistant Enterobacteriaceae (CRE) in a tertiary medical centre in Malaysia. Materials & Methods: A total of 13,098 Enterobacteriaceae isolates from various clinical samples were sent to our laboratory between January 2011 and December 2012. Of these, 90 demonstrated reduced susceptibility to at least one carbapenem and were included in this study. Only 88 isolates were successfully subcultured on blood agar (BA). Another 2 isolates failed to grow and were excluded. Of the 88, 2 isolates had the same identification number (repetitive isolates); therefore, 1 isolate was excluded from further analyses. Only 87 isolates were subjected to molecular detection of the blaOXA-48 and blaOXA-181 genes by polymerase chain reaction. Results: Eighty-seven non-repetitive isolates grew following subculture on BA. Of these, 9 (10.34%) were positive for OXA-48 (7 Klebsiella pneumoniae, 2 Escherichia coli). Each isolate originated from different patients. All patients had a history of treatment with at least one cephalosporin and/or carbapenem prior to the isolation of OXA-48 CRE. OXA-181 was detected in one (1.15%) out of the 87 isolates; Conclusions: The prevalence of OXA-48 and OXA-181 CRE among all Enterobacteriaceae isolates in our institution is 0.069% and 0.008%, respectively. Nevertheless, our findings suggest that OXA48 and OXA-181 carbapenemases appear to be important and possibly under-recognised causes of carbapenem resistance in Malaysia.

Performance of "RESIST-3 O.K.N. K-SeT" immunochromatographic assay for the detection of OXA-48 like, KPC, and NDM carbapenemases in Klebsiella pneumoniae in Turkey

ABSTRACT In this study, the performance of the "RESIST-3 O.K.N. K-SeT" (Coris BioConcept, Gembloux, Belgium) immunochromatographic assay was evaluated in 132 Klebsiella pneumoniae comprising 102 carbapenem resistant and 30 carbapenem susceptible isolates. Genotypically known isolates of Gram negative bacteria (n = 22) including various species were also tested by the assay as controls. The isolates tested by the immunochromatographic assay and also were run PCR for bla KPC, bla IMP, bla VIM, bla NDM, and bla OXA-48. The rates of bla NDM, bla OXA-48, and bla KPC in carbapenem resistant isolates were found at 52.9%, 39.2%, and 2.0%, respectively. Both bla NDM and bla OXA-48 were found in six (5.9%) isolates. The results of the assay showed 100% concordance with those obtained by PCR in 132 K. pneumoniae. The agreement between the two methods was found to be identical at the isolate level. The assay also correctly detected all genotypically known isolates of Escherichia coli, Serratia marcescens, Citrobacter freundii, Enterobacter cloacae, K. pneumoniae carrying bla KPC, bla NDM, and/or bla OXA-48. On the other hand, the assay did not exhibit any cross-reaction in control isolates harboring bla IMP and bla VIM. We conclude that the RESIST-3 O.K.N. K-SeT is a reliable, rapid, and user friendly test and we recommend it for routine diagnostic laboratories.

Rapid detection of the commonly encountered carbapenemases (New Delhi metallo-?-lactamase, OXA-48/181) directly from various clinical samples using multiplex real-time polymerase chain reaction assay

Background: Resistance due to New Delhi metallo-?-lactamase (NDM) and OXA-48/181 continues to emerge as a threat which is associated with nosocomial outbreaks and is a serious healthcare concern. Phenotypic detection being laborious and time-consuming requires rapid detection of NDM and OXA-48/181, which is achieved through real-time polymerase chain reaction (RT-PCR). Materials and Methods: In this study, RT-PCR assay was developed to simultaneously detect NDM and OXA-48/181. The assay was validated on 102 non-duplicate, phenotypically characterised clinical samples. Results: The assay showed a sensitivity and specificity of 97% and 100% for the detection of carbapenemases in comparison to conventional PCR. The in-house developed multiplex RT-PCR would help to rule-in the presence of NDM and OXA-48/181. Conclusions: Rapid detection of these carbapenemases would be assist in better patient management, in terms of accurate antimicrobial treatment, help in cohorting infected from uninfected patient to prevent spread.

Molecular Characterization of Extended Spectrum β-Lactamases, Ampccephalosporinases and Carbapenemases in Klebsiellapneumoniae Causing Bacteremia at Charles Nicolle Hospital of Tunisia.

Purpose of the Study: This study was conducted to detect and characterize the genes encoding extended spectrum β-lactamases and associated β-lactamases (carbapenemases and Ambler Class C β-lactamases). Patients and Methods: In 2011, out of the 65 non-duplicative Klebsiellapneumoniae collected from blood culture at Charles Nicolle hospital of Tunisia, 36 were resistant to 3rd generation cephalosporin. Results: All strains showed a double disk synergy test positive. They were mainly isolated in intensive care unit (31%). They were frequently resistant to most antibiotics tested, except colistin and tigecyclin. Five isolates (13%) showed reduced susceptibility to carbapenems. blaCTX-M-15 was harbored by 35 strains and blaSHV-12 by one. blaCTX-M-15 were associated with blaTEM-1 (n=21), blaOXA-48 and blaCMY-2 (n=1) and blaOXA-48and blaTEM-1 (n=4). The conjugation wassuccessfulfor4/5 strains (3 harboring blaCTX-M-15 and one blaSHV-12). The plasmids carrying the blaCTX-M-15 were assigned to IncN or IncL/M only for 2 strains. The remaining blaCTX-M-15-carrying plasmid was negative for all of the replicons tested as well as the blaSHV-12-carrying plasmid. Conclusion: Our results confirm the spread of CTX-M-15 in our institution. To our knowledge, this is the first report of K. pneumoniae coproducing CTX-M-15, CMY-2 and OXA-48. The implementation of preventive measures against the spread of these multiresistant bacteria is needed.

Distribution of beta-Lactamase Genes Among Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated From Patients in Turkey

BACKGROUND: The emergence of carbapenem-resistant Klebsiella pneumoniae poses a serious problem to antibiotic management. We investigated the beta-lactamases in a group of carbapenem-resistant K. pneumoniae clinical isolates from Turkey. METHODS: Thirty-seven strains of K. pneumoniae isolated from various clinical specimens were analyzed by antimicrobial susceptibility testing, PCR for the detection of beta-lactamase genes, DNA sequencing, and repetitive extragenic palindronic (REP)-PCR analysis. RESULTS: All 37 isolates were resistant to ampicillin, ampicillin/sulbactam, piperacillin, piperacillin/tazobactam, ceftazidime, cefoperazone/sulbactam, cefepime, imipenem, and meropenem. The lowest resistance rates were observed for colistin (2.7%), tigecycline (11%), and amikacin (19%). According to PCR and sequencing results, 98% (36/37) of strains carried at least one carbapenemase gene, with 32 (86%) carrying OXA-48 and 7 (19%) carrying NDM-1. No other carbapenemase genes were identified. All strains carried a CTX-M-2-like beta-lactamase, and some carried SHV- (97%), TEM- (9%), and CTX-M-1-like (62%) beta-lactamases. Sequence analysis of bla(TEM) genes identified a bla(TEM-166) with an amino acid change at position 53 (Arg53Gly) from bla(TEM-1b), the first report of a mutation in this region. REP-PCR analysis revealed that there were seven different clonal groups, and temporo-spatial links were identified within these groups. CONCLUSIONS: Combinations of beta-lactamases were found in all strains, with the most common being OXA-48, SHV, TEM, and CTX-M-type (76% of strains). We have reported, for the first time, a high prevalence of the NDM-1 (19%) carbapenemase in carbapenem-resistant K. pneumoniae from Turkey. These enzymes often co-exist with other beta-lactamases, such as TEM, SHV, and CTX-M beta-lactamases.

Emergence and Spread of OXA-48-Like Carbapenemase-Producing Enterobacteriaceae / 병원감염관리

Since 2001, ten more OXA-48 variants have been identified. Shewanella spp. has been thought to be the original host for OXA-48-like enzymes. These enzymes strongly hydrolyze penicillins and weakly hydrolyze carbapenems, with very weak activity against broad-spectrum cephalosporins. The OXA-48-like genes are always plasmid-borne and have been located in insertion sequences. OXA-48-like carbapenemases have been identified mainly from Turkey, North African countries, the Middle East, and India. Furthermore, the emergence and outbreak of OXA-48-like producers in Korea have been reported recently. Because some OXA-48-like-producing Enterobacteriaceae isolates do not exhibit resistance to broad-spectrum cephalosporins and only decreased susceptibility to carbapenems, their detection can be difficult. Adequate screening and detection methods are required to prevent and control the dissemination of OXA-48-like-producing Enterobacteriaceae.