Carbapenemase -producing Pseudomonas aeruginosa isolates from Turkey: first report of P. aeruginosa high-risk clones with VIM-5- and IMP-7-type carbapenemases in a tertiary hospital.

We investigated the presence of carbapenemases in carbapenem-resistant Pseudomonas aeruginosa isolates, which were collected over a 14-month period in a Turkish hospital, with in-depth molecular characterization of carbapenemase-producing isolates. Among 45 study isolates, 2 isolates were identified as carbapenemase producers by both Carba NP and Carbapenem Inactivation Method tests, and only 1 of them gave a positive result in polymerase chain reaction tests for a carbapenemase gene (blaVIM). Whole genome sequencing of the 2 isolates revealed the presence of blaVIM-5 gene in an ST308 isolate, while the other one expressed IMP-7 in an ST357 isolate; both STs are considered high-risk clones. The 2 carbapenemase-producing isolates were multidrug resistant, as they harbored other resistance determinants, including a variant of the recently described plasmid-encoded fluoroquinolone resistance determinant crpP gene, crpP-2. We report for the first time P. aeruginosa high-risk clones carrying VIM-5- and IMP-7-type carbapenemases with multiple resistance determinants in Turkey.

Evaluation of Teicoplanin Resistance Detected by Automated System in Coagulase Negative Staphylococci: A Comparison with Gradient Test and Broth Microdilution Methods.

Upon the observation of an increase in teicoplanin resistance rates in coagulase negative staphylococci (CoNS) isolates determined by the automated system, we aimed to compare the automated system and gradient test methods with the gold standard broth microdilution method. In addition, the effect of standard antimicrobial susceptibility guidelines on teicoplanin susceptibility test results in CoNS was investigated. A total of 81 CoNS isolates, 52 resistant and 29 susceptible to teicoplanin determined by automated system (Phoenix, Becton Dickinson, USA), were tested. The minimum inhibitory concentration (MIC) values were determined by gradient test (M.I.C. Evaluators, OXOID, UK) and broth microdilution methods. Susceptibility categories were determined according to EUCAST and CLSI criteria and the results were compared. Among 29 isolates found to be susceptible by automated system, one isolate was found resistant by gradient and broth microdilution tests. Of the 52 resistant isolates determined by automated system, 12 (23%) were found to be resistant by gradient test and 22 (42.3%) were resistant by broth microdilution. According to CLSI criteria, no resistant isolates were detected by broth microdilution and six isolates were intermediately susceptible while, two isolates were detected to be resistant and five isolates were found to be intermediately susceptible by the gradient test. In conclusion, compared to microdilution, teicoplanin resistance was detected at a higher rate in CoNS isolates by the automated system used. On the other hand, the gradient test method which is frequently used for confirmation was not reliable in MIC values close to the EUCAST breakpoint values (4 µg/mL). In addition, lower resistance rates were observed when the CLSI breakpoints were used in gradient test and broth microdilution methods.

Comparison of Carba NP-Direct, Carbapenem Inactivation Method, and ß-CARBA Tests for Detection of Carbapenemase Production in Enterobacteriaceae.

Rapid and accurate detection of carbapenemase-producing isolates are extremely important for management of antimicrobial therapy and the implementation of infection control measures. We evaluated the performance of Carba NP-direct, carbapenem inactivation method (CIM), and the commercial ß-CARBA tests for detection of carbapenemase production in Enterobacteriaceae. Enterobacteriaceae isolates with previously characterized carbapenemase types (n = 110) and non-carbapenemase-producing Escherichia coli (n = 15) isolates were tested. Sensitivities of Carba NP-direct, CIM, and ß-CARBA tests were 99.0%, 92.7%, and 93.6%, respectively, while specificity was 100% for all three tests. For ß-CARBA test, a 60-min incubation time instead of 30 increased the sensitivity to 98.1%, and lessened false negativity, particularly with OXA-48-like producers. Our results showed that Carba NP-direct, CIM, and ß-CARBA tests are useful tools for the reliable detection of carbapenemase activity in enterobacterial isolates. Carba NP-direct is a simple, rapid, and low-cost test for routine use.

VIM-1, VIM-2, and GES-5 Carbapenemases Among Pseudomonas aeruginosa Isolates at a Tertiary Hospital in Istanbul, Turkey.

Worldwide increase in carbapenem resistance and transferable carbapenemases are significant challenges in treatment of Pseudomonas aeruginosa infections. In this study, investigation of carbapenemase production in carbapenem-resistant P. aeruginosa isolates recovered from clinical specimens in a tertiary hospital was aimed. A total of 84 carbapenem-resistant P. aeruginosa isolates were examined. "Carbapenem inactivation method" (CIM) was used for phenotypic detection of carbapenemase production. The existence of blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48, and blaGES genes was investigated by polymerase chain reaction (PCR). Subtypes of the detected genes were identified by sequence analysis. Arbitrarily primed PCR (AP-PCR) was performed to evaluate the clonal relationship among the isolates. The presence of high-risk clones in carbapenemase producers was investigated by Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Three isolates (3.5%) were identified as carbapenemase producers by CIM tests, while PCR tests demonstrated three isolates carrying carbapenemase genes as well. blaVIM gene was found in two isolates and blaGES gene was found in one isolate. Sequence analysis demonstrated that the carbapenemases were VIM-1, VIM-2, and GES-5. AP-PCR yielded high clonal diversity among the isolates. According to MALDI-TOF MS analysis, none of the carbapenemase-producing strains belonged to the high-risk clones. In conclusion, the presence of VIM-1, VIM-2, and GES-5 type carbapenemases in P. aeruginosa isolates was demonstrated for the first time in our hospital, GES-5 being reported for the second time in Turkey. Our results will lead strategies for controlling the spread of carbapenemases and contribute to epidemiological data from Turkey.

Evaluation of the Carbapenem Inactivation Method for Detection of Carbapenemase-Producing Gram-Negative Bacteria in Comparison with the RAPIDEC CARBA NP.

Timely detection of carbapenemases by both phenotypic and genotypic methods is essential for developing strategies to control the spread of infections by carbapenem-resistant isolates and related morbidity and mortality. The aim of this study was to compare the performance of a commercial kit, the RAPIDEC® CARBA NP, and an in-house technique, the carbapenem inactivation method (CIM), against a panel of 136 carbapenemase- and noncarbapenemase-producing Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa isolates. RAPIDEC CARBA NP displayed 99% sensitivity and 100% specificity, whereas the sensitivity and specificity were 78% and 100% for the CIM test, respectively. A slight modification of the CIM test, a prolonged incubation time of 4 hours instead of two, increased the sensitivity of the test to 90% by diminishing false negativity particularly for A. baumannii. In conclusion, both tests possess a high performance and are practical for the detection of carbapenemases. Although RAPIDEC CARBA NP is a more rapid and reliable method, the CIM test may represent a useful tool for microbiology laboratories due to its simplicity and availability at any laboratory with low cost.

Corynebacterium propinquum bronchopneumonia in a child with ataxia telangiectasia.

Nondiphtherial Corynebacterium species isolated from clinical specimens are usually considered as contaminants by many clinicians when reported by microbiologists. However, an increasing number of studies have confirmed the importance of Corynebacterium spp. in the etiology of a variety of infectious processes. In this report, we present a case of bronchopneumonia caused by Corynebacterium propinquum. The infection occurred in a seven-year-old child who had a history of immunosuppression due to ataxia telangiectasia. The purulent sputum of the patient yielded a large number of polymorphonuclear leucocytes with abundant gram-positive coryneform bacilli in gram staining and pure growth of coryneform bacteria in culture. Definitive identification as C. propinquum was made by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing. C. propinquum should be recognized as a potential pathogen and included in the etiologic diagnostic algorithm, particularly in patients with immunosuppressive conditions.