Molecular characterization of methicillin-resistant Staphylococcus aureus strains by spa typing and pulsed field gel electrophoresis methods.

BACKGROUND: Rapid detection of sources and transmission routes by molecular methods provides key data for risk management of methicillin-resistant Staphylococcus aureus-induced infections acquired in both the community and hospitals. This study aimed to determine the clonal relationship of methicillin-resistant S. aureus strains isolated from our hospital by pulsed-field gel electrophoresis (PFGE) and Staphylococcal protein A (spa) typing methods and to identify the predominant clones in Cukurova Region, Turkey. RESULTS: All isolates analyzed by PFGE were distributed among 11 clusters. Clusters A (n = 19) and B (n = 27) were 84.1% similar and accounted for 61% of all samples. All isolates were distributed among 18 spa types, with the most common type being t030 with 31 isolates (41.3%), followed by t223 with nine isolates (12%) and t127 with seven isolates (9.3%). CONCLUSIONS: We found that t030 was the most common spa type in the area where the study was conducted, as also previously shown in studies undertaken in Turkey. However, the rate of t030 in our study was below the rates reported in the literature. We also detected some rare or sporadic spa types like t127, which has not been previously defined in our country. We consider that the spa typing and PFGE methods are useful for research on clonal relations in monitoring the changing prevalent clones in specific regions.

Molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae at a Turkish centre: Is the increase of resistance a threat for Europe?

OBJECTIVES: In recent years, carbapenem-resistant Klebsiella pneumoniae (CRKP) have become an important threat to hospitalised patients. This study aimed to identify the genetic mechanisms of carbapenem resistance in CRKP isolated from patients in a Turkish centre. METHODS: During 2013-2014, a total of 98 K. pneumoniae isolated from patients at Çukurova University Balcali Hospital (Adana, Turkey) determined phenotypically as resistant to carbapenems were screened genotypically for the presence of carbapenemase enzymes by multiplex PCR. RESULTS: Of the 98 patients for whom genetic investigation was made, 93 (94.9%) were adults, 56 (57.1%) were male and 81 (82.7%) were diagnosed as infected. The mean and median age were 51.8±20.5years and 55 years (range 1-89 years), respectively. The nosocomial infection rate was 87.8% (86/98). The mortality rate was 41.8% (41/98). Fifty-eight patients (59.2%) were admitted to intensive care units. Of the 12 non-nosocomial infections, 5 (41.7%) originated from the inpatient clinic of the urology department. The mean and median hospital length of stay (LOS) were 20.7±20.8days and 17days (range 0-90 days), respectively. The most common carbapenemase gene detected was blaOXA-48 (74.5%), followed by blaVIM (45.9%) and blaSME (37.8%). The blaNDM gene was detected in 20 isolates (20.4%). The most effective antibiotics were tigecycline and colistin, with susceptibility rates of 87.5% and 74.3%, respectively. CONCLUSIONS: Multiple resistance mechanisms were present in CRKP isolates in Turkey. Most of the isolates harboured blaOXA-48, blaVIM and blaSME genes; meanwhile, the rate of 20.4% for blaNDM is alarming.

NDM-1 and rmtC-Producing Klebsiella pneumoniae Isolates in Turkey.

BACKGROUND: The resistance of aminoglycosides in strains that produce beta-lactamase can be developed through the multidrug resistant encoding genes carried by common plasmids. Recently, the association between 16S rRNA methyltransferase resistance and beta-lactamase enzymes carried by the same plasmids has drawn increased attention from researchers, particularly the association in aminoglycoside-resistant strains with a minimum inhibitory concentration (MIC) of ≥ 256 µg/mL. OBJECTIVES: We aimed to investigate the co-existence of 16S rRNA methyltransferase and beta-lactamase genes in multidrug resistant (MDR) Klebsiella pneumoniae strains isolated from clinical samples. METHODS: We determined the molecular mechanisms of aminoglycoside resistance and its relationship with resistance to carbapenem and beta-lactam group antibiotics in 40 extended-spectrum beta-lactamase (ESBL)-positive carbapenem- and aminoglycoside-resistant K. pneumoniae strains. Multidrug resistant K. pneumoniae was isolated from various clinical samples in the faculty of medicine of Cukurova University, Turkey. First, the resistance of aminoglycoside and beta-lactam antibiotics was phenotypically investigated using the Kirby-Bauer disk diffusion test, double disk synergy test, and modified Hodge test. The MIC values of aminoglycoside were determined using the agar dilution method. Polymerase chain reaction was performed to detect the carbapenemases, ESBL, and 16S rRNA methyltransferase genes. The results were confirmed by a sequence analysis. RESULTS: Twenty K. pneumoniae strains showed resistance to amikacin, and 40 were resistant to gentamicin. The MIC value was found to be > 512 µg/mL in five amikacin-resistant strains and > 128 µg/mL in 10 gentamicin-resistant isolates. The rmtC gene, a type of 16S rRNA methyltransferase, was amplified in four isolates (MIC amikacin: > 512 µg/mL, gentamicin: > 128 µg/mL). Of these four isolates, three had the blaNDM-1 gene and all contained at least one ESBL gene. CONCLUSIONS: This study demonstrated the co-existence of rmtC and blaNDM-1 genes for the first time in Turkey. The spread of this resistant type should be monitored and limited through molecular surveillance.