The Link between Occurrence of Class I Integron and Acquired Aminoglycoside Resistance in Clinical MRSA Isolates

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial infections because of its high resistance. Here, we study the antibiotic resistance in MRSA clinical isolates and their relation to integron I occurrence. A total of 88 clinical Staphylococcusaureus isolates were collected. MRSA were identified by the disk diffusion method (DDM) and confirmed by PCR, and antibiogram was determined by DDM. Integron I, II and the aacA4 gene were investigated by PCR. Integrase-positive strains were analyzed for the presence of resistance gene cassettes by sequencing. All isolates were identified as MRSA by DDM and confirmed by PCR. All isolates were resistant to ampicillin and cefoxitin. Concerning aminoglycosides, the frequency of resistance was reported for streptomycin (60.7%), tobramycin (37.1%) gentamicin (36%), and for amikacin (15.9%). Integron I was detected in 41 isolates (46.6%), while integron II was detected in three isolates (3.4%). Sequencing of the integron I-cassette indicated the exclusive prevalence of addA gene variants mediating aminoglycoside resistance. The aacA4 gene was found in DNA of 31 isolates (35.22%). This study revealed the high existence of MRSA. Furthermore, the AacA4 gene and class I integron harboring aadA gene were predominant in MRSA isolates.

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“…MRSA is one of the most notorious and dangerous microorganisms that causes nosocomial infections. MRSA has the ability to readily acquire resistance to different types of antibiotics, which limits treatment success [ 7 , 51 ]. Therefore, there is an urgent need to discover effective antimicrobial compounds against MRSA.…”

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“…Bacterial isolates were recovered from human burn wound exudates and were purified and identified by morphology, pigmentation, Gram stain, biochemical tests, and growth on selective media. Antibiotic sensitivity was determined for the clinical isolates of P. aeruginosa by the disk diffusion method (DDM) [32] according to the Clinical and Laboratory Standard Institute. Bacterial culture media were purchased from Oxoid, (Hampshire, UK), and Hi-Media, (India), antibiotic discs were obtained from Oxoid, (Hampshire, UK) including Amikacin (AK, 30 µg), ampicillin (AM, 10 µg), ceftazidime (CAZ, 30 µg), cefoperazone (CFP, 75 µg), ciprofloxacin (CIP, 5 µg), gentamicin (CN, 10 µg), cefepime (FEP, 30 µg), gatifloxacin (GAT, 5 µg), and piperacillin/tazobactam (TPZ, 110 µg).…”

Promising FDA-approved drugs with efflux pump inhibitory activities against clinical isolates of Staphylococcus aureus

“…In hospitals environment, S. aureus exposed to different antibiotics, disinfectants and sanitizers; therefore, it gained an enormous resistance and became multidrug-resistant (MDR) [4,5]. In addition, the presence of resistance determinants on mobile genetic elements as transposons, integrons and plasmids has led to the wide spread of MDR strains [6][7][8].…”

“…Furthermore, methicillin resistant S. aureus (MRSA) can arise from chromosomal mutations that alter the drug binding sites, and from horizontal gene transfer of the mobile genetic element; staphylococcal cassette chromosome elements (SCCmec) [10,11]. MRSA is often resistant to many clinically used antibiotics, such as β-lactams, fluoroquinolones, aminoglycosides, macrolides and lincosamides in Egypt and worldwide [7,8,12].…”