Prevalence Of Carbapenemases Research Articles

Prevalence of carbapenemases among Gram-negative bacteria in Tunisia: first report of KPC-2 producing Acinetobacter baumannii.

The rapid evolution of the antibacterial resistance problem worldwide, including the Mediterranean countries, constitutes a real threat to public health. This study aims to characterize carbapenemase encoding genes among Gram-negative bacteria collected from some Tunisian hospitals. Twenty-two clinical carbapenem-resistant Gram-negative bacteria were recovered, and identified by the matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) method. Antibiotic resistance was tested by disk diffusion method on Muller-Hinton Agar. The minimum inhibitory concentration (MIC) for imipenem was revealed by the E-test method. Carbapenemase encoding genes were screened by polymerase chain reaction (PCR). Genetic relatedness was performed by the pulsed field gel electrophoresis (PFGE) method. Our isolates, identified as K. pneumoniae (n = 7), P. mirabilis (n = 1), A. baumannii (n = 13), and P. aeruginosa (n = 1), presented high MIC values for imipenem. Enterobacerales were resistant to carbapenems due to OXA-48 production. Only, four K. pneumoniae harbored the blaNDM-1 gene. VIM-2 production was detected in P. aeruginosa. However, OXA-23 production was observed in A. baumannii isolates, one of which co-produced the KPC-2 enzyme that was identified for the first time in Tunisia in this species. A high genetic diversity was demonstrated by pulsed-field gel electrophoresis in K. pneumoniae and A. baumannii after XbaI and ApaI digestion respectively. Our findings highlight the spread of various unrelated clones of carbapenemase-producers in some Tunisian hospitals as well as the spread of several carbapenemase types.

Proteus mirabilis – analysis of a concealed source of carbapenemases and development of a diagnostic algorithm for detection

ObjectivesTo analyse carbapenemases in Proteus mirabilis and assess the performance of carbapenemase detection assays. MethodsEighty-one clinical P. mirabilis isolates with high-level resistance at least to ampicillin (>32 mg/L) or previous detection of carbapenemases were selected and investigated by three susceptibility testing methods (microdilution, automated susceptibility testing, and disk diffusion), six phenotypic carbapenemase assays (CARBA NP, modified carbapenemase inactivation method [CIM], modified zinc-supplemented CIM, simplified CIM, faropenem, and carbapenem-containing agar), two immunochromatographic assays, and whole-genome sequencing. ResultsCarbapenemases were detected in 43 of 81 isolates (OXA-48-like [n = 13]; OXA-23 [n = 12]; OXA-58 [n = 12]; New Delhi metallo-β-lactamase (NDM) [n = 2]; Verona integron–encoded metallo-β-lactamase (VIM) [n = 2]; Imipenemase (IMP) [n = 1]; Klebsiella pneumoniae carbapenemase (KPC) [n = 1]). Carbapenemase-producing Proteus were frequently susceptible to ertapenem (26/43; 60%), meropenem (28/43; 65%), ceftazidime (33/43; 77%), and some even to piperacillin-tazobactam (9/43; 21%). Sensitivity/specificity of phenotypic tests were 30% (CI: 17–46%)/89% (CI: 75–97%) for CARBA NP, 74% (CI: 60–85%)/82% (CI: 67–91%) for faropenem, 91% (CI: 78–97%)/82% (CI: 66–92%) for simplified CIM, and 93% (CI: 81–99%)/100% (CI: 91–100%) for modified zinc-supplemented CIM. An algorithm for improved detection was developed, which demonstrated sensitivity/specificity of 100% (CI: 92–100%)/100% (CI: 91–100%) on the 81 isolates, and 100% (CI: 29–100%)/100% (CI: 96–100%) in a prospective analysis of additional 91 isolates. Interestingly, several OXA-23-producing isolates belonged to the same clonal lineage reported previously from France. DiscussionCurrent susceptibility testing methods and phenotypic tests frequently fail to detect carbapenemases in P. mirabilis, which could result in inadequate antibiotic treatment. In addition, the non-inclusion of blaOXA-23/OXA-58 in many molecular carbapenemase assays further impedes their detection. Therefore, the prevalence of carbapenemases in P. mirabilis is likely underestimated. With the herein proposed algorithm, carbapenemase-producing Proteus can be easily identified.

Prevalence of Carbapenemase and Extended-Spectrum β-Lactamase Producing Enterobacteriaceae: A Cross-Sectional Study.

Enterobacteriaceae have been classified as severely drug resistant bacteria by the World Health Organization due to their extensive production and dissemination of carbapenemases (CPs) and extended-spectrum β-lactamases (ESBL). The current study was conducted with the aim to determine the prevalence of CP- and ESBL-producing Enterobacteriaceae, as well as their antibiotic susceptibility profiles. For this, a hospital-based study was conducted which included 384 participants with bacterial infections. The collection and processing of specimens was conducted per standard microbiological protocol. The samples were inoculated on agar media plates to obtain the bacterial growths, and if they were positive for any bacterial growth, the antibiotic susceptibility testing was performed using disk diffusion method to check their antibiotic susceptibility patterns. The double disc diffusion as well as carbapenem inhibition techniques were used to examine the CP enzymes. Multiplex real-time PCR technique was performed to identify three distinct genetic types of CPs that have been identified in the Enterobacteriaceae (KPC, NDM, and OXA-48). A majority of participants (58.3%) in the current study were living in urban areas. A total of 227 (59.1%) patients were hospitalized. Furthermore, 26.04% of the patients were determined to be suffering from infections with Enterobacteriaceae. Escherichia coli was the most prevalent (9.1%) isolate overall, followed by Klebsiella pneumoniae (8.07%), Acinetobacter baumannii (2.6%), Pseudomonas aeruginosa (3.1%), Enterobacter cloacae (1.3%), Proteus spp. (1.3%), and Morganella spp. (0.5%). The studied patients were suffering from urinary tract infections (48.6%), blood stream infections (32.2%), wounds infection (11.9%), and respiratory infections (7.03%), confirmed with bacterial cultures. The resistance against carbapenems was seen in 31.4% of E. coli isolates, 25.8% in K. pneumoniae, 50% in P. aeruginosa, 25% in A. baumannii, and 20% in E. cloacae isolates. Such high rates of CP- and ESBL-producing Enterobacteriaceae are alarming, suggesting high spread in the study area. It is advised to implement better infection prevention and control strategies and conduct further nationwide screening of the carriers of these pathogens. This might help in reducing the burden of highly resistant bugs.

The Occurrence and Characterization of Class I, II, and III Integrons Among Carbapenemase-Producing Clinical Strains of Acinetobacter baumannii in Tehran, Iran

Background: Acinetobacter baumannii has emerged as a critical pathogen with high morbidity and mortality in long-term hospitalized patients who stay in intensive care units. Carbapenemases and integrons are two critical DNA elements that contribute to the emergence of multidrug-resistant (MDR) A. baumannii. Objectives: The current study aimed at characterization and molecular detection of class 1, 2, and 3 integrons among carbapenemase-producing A. baumannii strains recovered from a clinical setting in Tehran, Iran. Methods: A total of 65 non-replicated clinical strains were considered in this study. Class 1, 2, and 3 carbapenemase genes and clonal relatedness of the isolates were investigated by PCR assay. Results: The prevalence of carbapenemases was as follows: blaOXA23 (92.31%), blaVIM (69.23%), and blaNDM (1.54%). In addition, PCR sequencing confirmed the presence of gene cassette arrays consisting of aacA4-catB8-aadA1 (12/46, 26.09%), aadB-aadA1 (26.09%, 12/46), arr2-cm1A5 (30.43%, 14/46), and dfrA1-aadA1 (7.39%, 8/46) in class 1 integron and dfrA1-sat2 (52.94%, 9/17), and sat2-aadA1 (47.06%, 8/17) in class 2 integron. Sequence-based typing of both blaOXA-51-like and ampC revealed the following distribution of three different clone types among isolates: clonal complex (CC) 10 (46.15%, 30/65), CC2 (40%, 26/65), and CC3 (13.85%, 9/65). Statistical analysis showed that the presence of the intI1, blaOXA23, blaVIM, or blaNDM genes can significantly increase the acquiring MDR phenotypes in A. baumannii isolates. Conclusions: High prevalence of carbapenemase-producing A. baumannii harboring integrons is alarming public health. It seems that class 1 integron can be served as a predictive biomarker for the presence of MDR phenotypes in the clinical setting. However, integrons do not carry carbapenemases in these strains.

English

BACKGROUND The Carbapenemase Resistant Enterobacteriaceae (CRE) are associated with high rates of morbidity and mortality particularly amongst critically ill patients. Hence rapid laboratory detection of CRE hospitalized patients is highly desirable. The vast majority of carbapenemases belong to three of the four known classes of beta lactamases namely Ambler class A, Ambler class B metallobetalactamases (MBL) and Ambler class Doxacillinases (OXAs). The purpose of this study was to determine the prevalence of carbapenemases producing Enterobacteriaceae in clinical isolates in MBS hospital, Kota. METHODS This study was conducted in the Department of Microbiology at MBS Hospital, Kota from June 2020 to December 2020. 68 non repeat isolates (MDR) that were resistant to imipenem (10 mg) according to CLSI breakpoint were included in the present study. RESULTS Out of 68 imipenem resistant Enterobacteriaceae, 52 were carbapenemase producing as detected by Modified Hodge Test. As per our study, the prevalence of carbapenemase producing Enterobacteriaceae was 20.8%. Most commonly seen in K. pneumoniae isolated from urine and swab of critically ill and debilitated patients of surgical ward. CONCLUSIONS Curbing irrational usage of antimicrobials in India is urgently required. Thus, aggressive infection control efforts have been effective at decreasing rates of infections with KPC-producing bacteria in intensive care units and long-term acute care hospitals. Bundled interventions including enhanced environmental cleaning, active surveillance culturing and contact precautions, as well as antimicrobial stewardship are important in controlling KPC-producing bacteria. KEY WORDS Multi Drug Resistance Enterobacteriaceae (MDRE), Klebsiella Producing Carbapenemase (KPC), Carbapenem Resistant Enterobacteriaceae (CRE), Metallo Beta Lactamase (MBL), Modified Hodge Test (MHT)

Prevalence of carbapenemases and ESBL encoding genes among K. pneumoniae isolates obtained from an educational hospital in Ahvaz, Southwestern Iran

BackgroundK. pneumoniae is a gram-negative pathogen that common cause of nosocomial infections. The rapid spread of multi-drug resistant (MDR) K. pneumoniae is an important issue. This study aimed to identify carbapenemases (Klebsiella pneumoniae carbapenemase [KPC], oxacillinase- 48 [OXA-48], New Delhi metallo-β-lactamase-1 [NDM-1]), oxacillinase-181 [OXA-181] and extended-spectrum beta-lactamases (ESBL) (CTX-M-15) were identified among K. pneumoniae isolates in Ahvaz, Iran. MethodsIn this cross-sectional study, conducted from July 2018 to July 2019, isolates of K. pneumoniae obtained from various clinical samples. All Gram-negative bacilli isolates were differentiated on species level by standard biochemical tests. In following, antibiotic susceptibility testing by disk diffusion method, ESBLs, carbapenemase, metallo-beta-lactamase and blaCTX-M-15, blaKPC, blaOXA-48, blaNDM, and blaOXA-181 genes were performed. ResultsIn total, 120 clinical isolates of K. pneumoniae were obtained. The most effective antibiotics for K. pneumoniae isolates were colistin, imipenem, and doripenem, with 98.3%, 64.1%, and 64.1% susceptibility. Thirty-one isolates (25%) were resistant to meropenem disc and considered as carbapenem-resistant. A total of 78 isolates (65%) were ESBLs by double-disc synergy test (DDST) and 25 isolates (20.8%) produced metallo-beta-lactamase. Among 31 (25%) carbapenem-resistant isolates, 22 isolates (71%) hydrolyzed the meropenem and classified as carbapenemase producers. PCR assays revealed that prevalence of blaCTX-M-15, blaKPC, blaOXA-48, blaNDM, and blaOXA-181 genes was 36.7%, 10%, 64.15%, 1.7% and 8.3%, respectively. ConclusionThis study found a high prevalence of MDR K. pneumoniae harboring MBL and ESBL genes. It is recommended that local periodic. Surveys are performed for controlling antimicrobial resistance.

Molecular Detection of Carbapenem Resistant Gram Negative Bacterial Isolates from Dogs

Background: Carbapenems are beta-lactam antibiotics that are considered as the last line of therapy against multidrug resistant extended spectrum beta-lactamase. The resistance to carbapenems predominantly through carbapenemase is one of the most important emerging health problems worldwide in the therapy of clinical infections. The objective of the present study is to determine the presence of carbapenemase encoding genes among Gram- negative bacterial spp. associated with clinical infections in dogs. Methods: 30 Escherichia coli, 11 Klebsiella pneumoniae and three Pseudomonas aeruginosa isolated from urine, swabs from lesional skin and anterior vagina of dogs presented with different clinical ailments formed the samples for the study. Polymerase chain reaction was carried out to detect the presence of carbapenemase encoding genes viz., KPC, NDM, OXA, VIM and IMP among the isolates.Result: Out of the 44 Gram- negative isolates tested, 28 (76.3%) were positive for at least one tested carbapenemase gene. The highest frequency of carbapenemase recorded was for NDM followed by OXA-181, KPC, OXA-48 and VIM. Our study identified a high prevalence of carbapenemases among companion animals like dogs which could act as potential source of transmission of these resistance bacteria or their genomes to humans.

Molecular Epidemiology of Carbapenem-Resistant Enterobacterales Strains Isolated from Blood Cultures in Antalya, Turkey

The aim of this study was to investigate the prevalence of carbapenemase and CTX-M genes among 330 blood culture isolates of Enterobacterales with reduced susceptibility to at least 1 carbapenem, between 2010 and 2015. BD Max CRE assay and in-house PCR were used to detect carbapenemase and CTX-M genes. At least 1 carbapenemase gene was detected among 113 (74.3%) of the 152 carbapenem resistant isolates. The OXA-48 (69.7%) was the most common carbapenemase followed by VIM, NDM and IMP, whereas no tested isolates were KPC-positive. Eighty-six isolates (56.6%) had CTX-M and 65 had both OXA-48 and CTX-M. Carbapenemase production in Enterobacterales was significantly increased in years (P < .05). Our study indicates that there is ongoing endemic circulation of the OXA-48 producing organism in our facility. It is noteworthy that more than half of the OXA-48 producing strains also produced CTX-M enzyme.

Carbapenemases in Acinetobacter baumannii. Review of their dissemination in Latin America

Carbapenem resistance in gram-negative bacteria by production of carbapenemases is one of the most challenging issues regarding healthcare worldwide. We review the epidemiology and prevalence of carbapenemases in carbapenem-resistant Acinetobacter baumannii isolates from Latin American countries. High resistance rates to antimicrobial agents, particularly to carbapenems, are observed in this region. OXA-23 is the most widely disseminated class D-carbapenemase; it is present in all the countries of the region and is frequently associated to endemic clones CC113/CC79, CC104/CC15, CC110/ST25 and CC109/CC1. The emergence of OXA-72 and NDM-1 represents a novel finding which is observed simultaneously and without clonal relatedness in different countries, some of which are distant from one another, whereas OXA-143 is only present in Brazil. Further collaborative intraregional studies would provide a better understanding of these issues in most of the countries and thus, policies to control the spread of these isolates could be implemented.

Prevalence of carbapenemase in Enterobacteriaceae with decreased susceptibility to carbapenems isolated in a tertiary referral hospital

ABSTRACT Infections caused by carbapenem-resistant Enterobacteriaceae are a serious public health issue. This work aims to analyze the resistance mechanisms related to Enterobacteriaceae with decreased susceptibility to carbapenems isolated at the Hospital Julia Kubitschek (HJK) of the Minas Gerais State Founding Hospital [Fundacao Hospitalar do Estado de Minas Gerais (FHEMIG)], Brazil. Seventy-one strains with reduced susceptibility to carbapenems were found, and 45/71 (63.4%) were Klebsiella pneumoniae carbapenems (KPC) producers.

Prevalence and impact of Carbapenemase-encoding genes in Clinical isolates of Carbepenem-Resistant Pseudomonas aeruginosa

Multidrug resistant Pseudomonas aeruginosa (MDRPA) and carbapenem-resistant Pseudomonas auruginosa (CRPA) are difficult to treat. Carbapenem resistance is due to multiple mechanisms and among these mechanisms production of carbapenemases is the most important. The aim of this study was investigating the prevalence of carbapenemase encoding genes that were associated with CRPA. Bacterial isolation, identification and antibiotic sensitivity were performed. Selected CRPA isolates were investigated for the presence of specific carbepenemase- encoding genes. Gene mutation was enhanced by exposure of the bacterial cells to UV radiation. Among the investigated CRPA isolates (12/22, 54.5%) were harboring genes for carbapenemases production. KPC, VIM, IMP genes were detected in (11/22, 50%), (5/22, 22.7%) and (4/22, 18.2%) respectively, while SME, NDM-1(using two pairs of primers) and OXA genes were not detected in any of the tested CRPA isolates. In the absence of KPC, IMP and VIM genes in bacterial mutants, MIC for carbapenems were decreased from ≥16 to ≤2 mg/L. The prevalence of cabapenamase encoding genes was relatively high in the current study, which was reported in association with high mortality rate. In contrast to a recent publication, KPC and IMP genes were detected in Kuwait hospitals and their impact on resistance was proved.

First report of an Escherichia coli strain from swine carrying an OXA-181 carbapenemase and the colistin resistance determinant MCR-1

Plasmid-mediated resistance to carbapenems and colistin in Enterobacteriaceae represents an emerging public health threat. Although animals have been identified as a relevant source of multidrug-resistant (MDR) bacteria, there are only a few reports on the presence of carbapenemases in animal isolates. In this study, 7850 faecal Escherichia coli isolates obtained from 2160 pigs were screened for carbapenem non-susceptibility using Mueller–Hinton agar supplemented with meropenem. Eleven isolates showed growth on meropenem-containing agar but only two proved positive by PCR for a carbapenemase gene, namely blaOXA-48-like. The two isolates were obtained from different pigs housed at the same farm in Italy and were not genetically related by multilocus sequence typing (MLST), comprising ST359 and ST641. Whole-genome sequencing revealed the presence of blaOXA-181 in both isolates; in addition, the colistin resistance gene mcr-1 and aminoglycoside resistance gene armA were found in one isolate. The blaOXA-181 resistance gene was located on a 51.5-kb non-conjugative plasmid of replicon type IncX3 and the mcr-1 gene on a 33.3-kb transferable IncX4 plasmid. The high nucleotide similarity (>99%) of plasmids pEcIHIT31346-OXA-181 and pEcIHIT31346-MCR-1 to published plasmids from various human and animal sources suggests that specific antibiotic resistance plasmids are circulating among E. coli strains worldwide and across vertebrate species barriers. Although carbapenems are not licensed for use in livestock and the overall prevalence of carbapenemases in porcine E. coli appears to be low, the current findings indicate that even pigs can host MDR strains with accumulated plasmid-mediated resistance against several last-line antibiotics.

Prevalence of Carbapenemases among Klebsiella Pneumoniae Strains Isolated from Respiratory Tract Specimens

Background: The intensive use of carbapenems has resulted in the emergence of carbapenem-resistant isolates. Carbapenemase-producing Klebsiella pneumoniae has rapidly emerged as a major pathogen among carbapenemase-producing bacteria. Objectives: We aimed to characterize 28 Klebsiella pneumoniae strains isolated from respiratory specimens in Assiut University Hospitals, Egypt from May 2015 to August 2015. Methodology: We characterized the antimicrobial susceptibility profile of Klebsiella pneumoniae by disk diffusion method. Detection of carbapenemase genes (blaKPC-1, blaVIM-1, blaVIM-2, blaIMP-1, blaIMP-2, and bla-SPM-1) was performed by polymerase chain reaction. Results: Patients infected by Klebsiella pneumoniae experienced different types of respiratory infections. Carbapenemase genes were detected in 12 (43%) Klebsiella pneumoniae isolates. blaKPC-1 was found in 9 (32%) isolates, blaVIM-1 was detected in two (7%) isolates, and blaIMP-1 gene was expressed by two (7%) isolates. blaVIM-2, blaIMP-2, and blaSPM-1 genes were not expressed by any of the isolates. Carbapenemase-producing Klebsiella pneumoniae showed higher resistance rates to carbapenems and other antibiotics. Conclusion: The high resistance rates in our carbapenemase-producing strains impose limitations in the therapeutic options available. This should alert the medical authorities of our University to establish rigorous methods for more efficiently control the dissemination of antimicrobial resistance genes in the hospital environment.

Characterization of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae from a healthcare region in Hong Kong.

Carbapenem-resistant Enterobacteriaceae represents a major public health issue. This study investigated the clonality and resistance mechanisms of 92 carbapenem-resistant E. coli (n = 21) and K. pneumoniae (n = 71) isolates collected consecutively from clinical specimens and patients at high risk of carriage between 2010 and 2012 in a healthcare region in Hong Kong. Combined disk tests (CDTs) and the Carba NP test were used for phenotypic detection of carbapenemases. PCR assays were used to detect carbapenemase genes. All isolates were intermediate or resistant to at least one carbapenem. Nine (9.8%) isolates were genotypic carbapenemase producers and included six K. pneumoniae (one ST1306/bla IMP-4, one ST889/bla IMP-4, two ST11/bla KPC-2, one ST258/bla KPC-2, one ST483/bla NDM-1) and three E. coli (one ST131/bla IMP-4, two ST744/ bla NDM-1) isolates. All nine isolates carrying carbapenemase genes could be detected by the CDTs and the Carba NP test. PCR identified bla CTX-M and bla AmpC alone or in combination in 77.8% (7/9) and 96.4% (80/83) of the carbapenemase-producers and non-producers, respectively. Porin loss was detected in 22.2% (2/9) and 59.0% (49/83) of the carbapenemase-producers and non-producers, respectively. Overall, the E. coli clones were diverse (14 different STs), but 36.6% (26/71) of the K. pneumoniae isolates belonged to ST11. In conclusion, the prevalence of carbapenemases among carbapenem-nonsusceptible E. coli and K. pneumoniae remained low in Hong Kong. Porin loss combined with AmpC and/or CTX-M type ESBL was the major mechanism of carbapenem resistance in the study population.

Screening for Klebsiella pneumoniae producing carbapenemase (KPC) in Prato (Italy)

In this study, the prevalence of carbapenemase in the area of Prato (Italy), from January 2011 to August 2013, is reported. Samples showing carbapenem resistance were tested for lactamase production with disc diffusion and molecular methods. Totally, 48 out of 1542 patients with K. pneumoniae showed carbapenem resistance (42 KPC 5 MBL and 1 OXA-48).

Epidemiology of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii in Mediterranean countries.

The emergence and global spread of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii are of great concern to health services worldwide. These β-lactamases hydrolyse almost all β-lactams, are plasmid-encoded, and are easily transferable among bacterial species. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 types. Their current extensive spread worldwide in Enterobacteriaceae is an important source of concern. Infections caused by these bacteria have limited treatment options and have been associated with high mortality rates. Carbapenemase producers are mainly identified among Klebsiella pneumoniae, Escherichia coli, and A. baumannii and still mostly in hospital settings and rarely in the community. The Mediterranean region is of interest due to a great diversity and population mixing. The prevalence of carbapenemases is particularly high, with this area constituting one of the most important reservoirs. The types of carbapenemase vary among countries, partially depending on the population exchange relationship between the regions and the possible reservoirs of each carbapenemase. This review described the epidemiology of carbapenemases produced by enterobacteria and A. baumannii in this part of the world highlighting the worrisome situation and the need to screen and detect these enzymes to prevent and control their dissemination.

Comparison of phenotypic methods for the detection of IMP producing enterobacteriaceae in queensland

Background The prevalence of carbapenemase producing enterobacteriaceae (CPE), particularly IMP producers (IMP), in Australia is increasing. Optimal methods for detection of IMP CPE are unknown. We compare six phenotypic methods to determine the most sensitive method for the detection of IMP CPE. Methods We tested 25 molecularly confirmed IMP CPE producers, including 16 Enterobacter cloacae , collected from Queensland Health hospitals. The following methods were performed: disc susceptibility testing (DST), minimum inhibitory concentrations (MICs) by E-test, broth microdilution (BMD) and Vitek 2, modified hodge test (MHT) and Carba NP test. Results Meropenem MIC range (MIC 50/90 ) was 0.25->32 (4/16), 0.25-32(2/16), 1->16(>16/>16) for BMD, E-test and Vitek 2, respectively. Seventeen percent of isolates had a Vitek 2 meropenem MIC between 1-2 |xg/mL. Using EUCAST breakpoints, all isolates tested resistant by Ertapenem E-test and all except for one isolate was resistant by ertapenem DST. CLSI breakpoints increased detection of CPE with meropenem and imipenem. Carba NP test and MHT provided positive results for all isolates. Conclusion: Our results indicate that isolates with a Vitek 2 meropenem MIC of ≥1 μg/mL should undergo further phenotypic testing. Ertapenem DST, ertapenem E-test, Carba NP test and MHT are the most sensitive methods for detection of IMP CPE.

Types and Prevalence of Carbapenem-Resistant Acinetobacter calcoaceticus-Acinetobacter baumannii Complex in Northern Taiwan

The frequency of the carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii (CRACB) complex increases annually in our hospitals. However, the types and prevalence of carbapenemases among isolates still remain unclear. In this study, we identified and collected 672 carbapenem-resistant isolates from a medical center in Northern Taiwan between April and December of 2010. There were 577 genospecies 2 (Acinetobacter baumannii), 79 genospecies 13TU, and 16 genospecies 3 isolates. The isolates had an acquired blaOXA-24-like gene, which was confirmed by sequencing for the encoded OXA-72 carbapenemase, and were often associated with high-level carbapenem resistance. These CRACB complex isolates remained susceptible to colistin (100%). The genotyping of isolates was conducted using pulsed-field gel electrophoresis with ApaI digestion. In most clonally related groups, patients were from both branch hospitals. The results indicate that interhospital dissemination of clones occurred. This study provides updated data on the types and prevalence of the CRACB complex. In addition, it presents a warning on the emergence and spread of CRACB complex harboring blaOXA-24-like genes in northern Taiwan.

Detection of Carbapenemase-Encoding Genes Among Clinical Isolates of Pseudomonas aeruginosa in a Chinese Burn Unit

The carbapenemases have recently emerged as molecules implicated in one of the most feared bacterial resistance mechanisms because of their ability to hydrolyze virtually all lactamase agents and their highly mobile genes. This study aimed to investigate the prevalence of carbapenemase and antimicrobial susceptibilities of Pseudomonas aeruginosa isolated from burn patients in Chongqing, China. Antimicrobial susceptibility of 111 isolates was determined by the disc agar diffusion test and the agar dilution method. Random Amplification of Polymorphic DNA polymerase chain reaction analysis revealed 111 P. aeruginosa 42 genotypes. Carbapenemase genes were amplified by polymerase chain reaction and the sequence verified by blast. Ninety-three of 111 (83.8%) isolates were resistant to imipenem; all of them had developed multidrug resistance and exhibited higher resistant rates compared with the imipenem-susceptible Pseudomonas. Ciprofloxacin was the most effective antipseudomonal agent. Thirty-three of the isolates were identified to contain the metallo-β-lactamase blaIMP-4 gene and belong to different Random Amplification of Polymorphic DNA polymerase chain reactiongenotypes. In conclusion, the high prevalence of multidrug resistance (94.6%) and the production of blaIMP-4 genes in P. aeruginosa isolates in burn patients highlight the necessity of considering these issues in burn hospitals.