RESUMEN
Background and Aims: Given the importance of aminoglycoside resistance in nosocomial and community infections caused by bacterial pathogenes such as Klebsiella pneumoniae [K. pneumoniae], the aim of this study was to determine the frequency of aac [6']- Ib and aac [3]- IIa, the genes encoding aminoglycoside modifying enzymes involved in aminoglycoside resistance
Material and Methods: A total of 100 K. pneumonia isolates were collected from hospitalized patients from April to September 2015 in Borujerd hospitals. Conventional microbiological tests were carried out to detect and confirm K. pneumonia isolates. Antibiotic susceptibility of isolates was detected by disk diffusion methods. The presence of the aac[6']-Ib and aac[3]-IIa genes which encode aminoglycoside modifying enzymes was determined by polymerase chain reaction
Results: Among 100 K. pneumonia isolates, 34% showed resistance to gentamicin and 21% to amikacin. Resistance to both gentamicin and amikacin was detected in 18% of the isolates. Multi-resistance phenotypes were detected in 71% of the isolates. The aac [3]-IIa and aac[6']-Ib genes were found in 71% [n=24] and 5.8% [n=2] of aminoglycoside resistant isolates, respectively. Simultaneous carriage of aac [3]-IIa and aac[6']-Ib was detected in 64% [n=22] of the aminoglycoside resistant isolates
Conclusions: The results of this study showed the presence of aac [3]-IIa genes in more than 70% of the aminoglycosides resistant K. pneumoniae strains; this may be due to the transmission of this gene through mobile genetic elements that create a high risk of rapid spread of these genes in hospitals
RESUMEN
Background: The aim of this study was to compare the biofilm formation and the prevalence of biofilm-associated genes between the isolates of methicillin-resistant [MRSA] and methicillin-susceptible [MSSA] Staphylococcus aureus
Methods: In total, 209 S. aureus isolates were collected. The antibiotic susceptibility test was conducted using nine antibiotics according to the guidelines of Clinical and Laboratory Standards Institute. Phenotypic biofilm formation was performed with microtiter plate assay. The polymerase chain reaction was employed to detect icaA, icaD, icaB, icaC, clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, bbp, mecA, and SCCmec types as well as agr group genes with specific primers
Results: Sixty-four [30.62%] isolates were resistant to methicillin, and 54 [83%] MRSA harbored SCCmec III. Furthermore, 122 [58.3%] isolates belonged to agr group I. Twenty-six [36.1%] MRSA and 42 [28.9%] MSSA isolates were strong biofilm producers [no significant difference]. The prevalence of icaA, icaD, icaB, and icaC genes in MSSA isolates was 71, 41, 76, and 72%, respectively. The frequency of clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, and bbp in MSSA was 100, 100, 56, 46, 74, 54, 78%, 11, and 1%, respectively. However, in MRSA isolates, the frequency was 97, 97, 64, 51, 76, 56, 79, and 12% with no track of bbp, respectively
Conclusion: Statistical difference between MSSA and MRSA regarding biofilm formation and the frequency of all biofilm-encoding genes was not significant. The majority of the S. aureus isolates harbored clfA, clfB, eno, fib, icaA, and icaD genes