Aminoglycoside-resistant staphylococci in Greece: Prevalence and resistance mechanisms

Department of Microbiology, University Hospital of Larissa, Mezourlo, 41110 Larissa, Greece.
European Journal of Clinical Microbiology (Impact Factor: 2.67). 05/2011; 30(5):701-5. DOI: 10.1007/s10096-010-1132-7
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Available from: Zoe H Dailiana, Oct 04, 2015
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    • "50% of CNS isolates there existed a correlation between the phenotype of amikacin resistance and the genotype [13]. According to recommendations of EUCAST (2012) [10], the isolates demonstrating gentamicin resistance are to be treated as having a general aminoglycoside resistance with the exception of streptomycin, as this one is most probably coded by the aac(6′)/aph(2″) gene the product of which modifies antibiotics such as gentamicin, kanamycin, tobramycin and amikacin [22]. The phenotype of gentamicin resistance, despite the missing aac(6′)/aph(2″) gene, may be caused by the presence of other genes coding aminoglycoside resistance which were not determined in the method used. "
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    ABSTRACT: Multi-drug resistant coagulaso-negative staphylococci (CNS) have become an increasing problem in nosocomial infections connected with the presence of medical devices. The paper aimed to analyze the prevalence of antibiotic resistance in CNS isolated from invasive infection in very low birth weight (VLBW) neonates. Continuous prospective target surveillance of infections was conducted in 2009 at two Polish NICUs that participated in the Polish Neonatology Surveillance Network (PNSN). The study covered 386 neonates with VLBW (<=1500 g), among which 262 cases of invasive infection were detected with predominance of CNS (123; 47%). Altogether, 100 CNS strains were analyzed. The resistance phenotypes were determined according to EUCAST. Resistance genes: mecA, ermA, ermB, ermC, mrsA, aac(6[prime])/aph(2[prime][prime]), ant(4[prime])-Ia and aph(3[prime])-IIIa were detected using multiplex PCR. The most common species was S. epidermidis (63%), then S. haemolyticus (28%) and other CNS (9%). Among S. epidermidis, 98% of isolates were resistant to methicillin, 90% to erythromycin, 39% to clindamycin, 95% to gentamicin, 60% to amikacin, 36% to ofloxacin, 2% to tigecycline, 3% to linezolid and 13% to teicoplanin. Among S. haemolyticus isolates, 100% were resistant to methicillin, erythromycin and gentamicin, 18% to clindamycin, 50% to amikacin, 86% to ofloxacin, 14% to tigecycline and 4% to teicoplanin. No resistance to linezolid was detected for S. haemolyticus isolates. Moreover, all isolates of S. epidermidis and S. haemolyticus were susceptible to vancomycin. The mecA gene was detected in 98% of S. epidermidis isolates and all of S. haemolyticus ones. Among macrolide resistance isolates, the ermC was most common in S. epidermidis (60%) while msrA was prevalent in S. haemolyticus (93%). The ermC gene was indicated in all isolates with cMLSB, whereas mrsA was found in isolates with MSB phenotype. Of the aminoglycoside resistance genes, aac(6[prime])/aph(2[prime][prime]) were present alone in 83% of S. epidermidis, whereas aac(6[prime])/aph(2[prime][prime]) with aph(3[prime])-IIIa were predominant in 84% of S. haemolyticus. Knowing the epidemiology and antibiotic resistance of CNS isolated from invasive infection in VLBW neonates is a key step in developing targeted prevention strategies and reducing antibiotic consumption.
    Annals of Clinical Microbiology and Antimicrobials 12/2013; 12(1):41. DOI:10.1186/1476-0711-12-41 · 2.19 Impact Factor
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    ABSTRACT: Aminoglycosides are potent bactericidal agents that play an important role in antistapylococcal therapy. In this study, we used a multiplex polymerase chain reaction assay to investigate the prevalence of aac(6')-Ie/aph(2''), ant(4')-Ia, and aph(3')-IIIa, the genes encoding the most clinically prevalent aminoglycoside-modifying enzymes, and simultaneous detection of the methicillin resistance gene, mecA, in Staphylococcus aureus isolates. A total of 100 S. aureus clinical isolates were collected and tested by disk diffusion and agar dilution method for susceptibility testing. All isolates were screened for the presence of the three aminoglycoside-modifying enzyme genes and the methicillin resistance gene. The ant(4')-Ia was the most frequent gene (58%), and aac(6')-Ie/aph(2'') and aph(3')-IIIa genes were found in 46% and 6% of the isolates, respectively. All isolates harboring the aac(6')-Ie/aph(2'') gene were resistant to gentamicin (100% concordance). Seventy-one percent of the isolates demonstrated resistance to at least one of the aminoglycosides tested. PCR results showed that 53% of all isolates harbored the mecA gene. Aminoglycoside resistance was closely associated with oxacillin resistance (p < 0.05). In conclusion, because of the high rate of aminoglycoside resistance among S. aureus clinical isolates observed in this study, periodic surveillance on the resistance prevalence should be performed.
    Microbial drug resistance (Larchmont, N.Y.) 07/2009; 15(2):109-13. DOI:10.1089/mdr.2009.0897 · 2.49 Impact Factor
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    Microbial pathogens and strategies for combating them: science, technology and education, Microbiology Book Series, number #4 01/2013;
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