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Antibiotic Susceptibility and Plasmid Profiles of Staphylococcus aureus Strains Isolated from Bovine Subclinical Mastitis in Tabriz, Iran
Katayoon Nofouzi , Alaleh Rakhshanpoor, Reza Asadpour,
Volume 11, Issue 4 (7-2017)
Abstract
ABSTRACT
       Background and Objectives: Mastitis caused by Staphylococcus aureus is a widely distributed disease in cattle, goats and sheep. The infection is often subclinical in cattle, leading to reduced milk production and quality, but acute catarrhal or even gangrenous inflammation may also occur. The aim of this study was to investigate resistance of S. aureus isolates from bovine subclinical mastitis to a number of antibiotics.
          Methods: Milk samples were collected from 120 cows in different regions of Tabriz, Iran. Milk samples were cultured and bacteriological identification was performed. Antimicrobial susceptibility of the isolates was assessed by determining minimum inhibitory concentration. Plasmid DNA was extracted by an alkaline lysis method. 
         Results: The highest frequency of resistance was observed against gentamicin (100%) and β- lactam antibiotics including amoxicillin (96%), ampicillin (40%) and penicillin (96%). The isolates mostly contained large plasmids, which might harbor acquired antibiotic resistance.
         Conclusion: The results confirm the high frequency of antibiotic resistance among staphylococci isolated from bovine subclinical mastitis.
           Keywords: Anti-infective Agents, Cattle, Staphylococcus Aureus, Mastitis, Plasmids.

Frequency of Plasmid-Located Quinolone Resistance Genes in Clinical Isolates of Klebsiella pneumoniae in Northern Iran
Leila Asadpour, Mohammad Moradi Bazghaleh,
Volume 17, Issue 3 (5-2023)
Abstract
Background and objectives: Fluoroquinolones are a class of broad-spectrum antimicrobials typically used for the treatment of lower urinary tract infections. We aimed to determine the frequency of quinolone resistance genes in Klebsiella pneumoniae isolates from urinary tract infections in Guilan Province, Iran.
Methods: The resistance of 114 clinical isolates of K. pneumoniae to common fluoroquinolones and the minimum inhibitory concentration of ciprofloxacin were determined by disk diffusion and broth microdilution methods, respectively. Frequency of five plasmid-mediated quinolone resistance (PMQR) genes including qnrA, qnrB, qnrS, qepA, and aac (6')-Ib-cr was determined by PCR. 

Results. According to phenotypic assays, 60 isolates (52.6%) were resistant to at least one quinolone compound, 42 isolates (36.8%) were resistant to all tested quinolones, and 28 isolates (24.6%) showed a high level of ciprofloxacin resistance. In addition, aac(6')-Ib-cr was the most common PMQR gene (𝑛 = 44), followed by qnrS (𝑛 = 32), and qnrB (𝑛 = 21).
Conclusion: The possible dissemination of PMQR genes poses a serious threat to the management of infections by resistant Klebsiella pneumoniae.
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