Staphylococcus aureus is the primary cause of nosocomial infections. It produces potent toxins and causes superficial lesions, systemic diseases, and several toxaemic syndromes. In this study, we determined the role of efflux pump in conferring resistance to fluoroquinolones in the biofilm of methicillinresistant Staphylococcus aureus (MRSA) and methicillin sensitive S. aureus (MSSA) strains. We selected five strains of S. aureus comprising three methicillin sensitive strains, including ATCC25923, and two strains of methicillinresistant S. aureus.Thioridazine, chlorpromazine, carbonyl cyanide 3-chloro-phenylhydrazone and reserpine showed activity against MSSA strains. Whereas, thioridazine and chlorpromazine were active against MRSAstrains too.Thioridazine and chlorpromazine showed a significant decrease in biofilm formation of MSSA strain 2493, and MRSA strain UC1079 compared to the control strain ATCC25923. Thioridazine showed a similar effect on MSSA strain N297214 and MRSA strain N307002. Four to eight-fold increase was found in the expression of efflux pump genes with ethidium bromide, ciprofloxacin, and moxifloxacin in these strains. However, a decrease in the expression of norB, norC, abcA and mepA was observed in MSSA, and MRSA strains with thioridazine, chlorpromazine and naringenin. This study, thus demonstrate that the major facilitator superfamily, multidrug and toxin compound extrusion, and ATP binding cassette family of efflux pumps play an essential role in developing antibiotic resistance and biofilm formation. It is the first report on existence of efflux pump genes in biofilm beside antibiotic resistance for fluoroquinolones in MRSA and MSSAstrains, which need further characterization.

中文翻译：

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耐甲氧西林和对甲氧西林敏感的金黄色葡萄球菌菌株的外排泵和生物膜形成

金黄色葡萄球菌是医院感染的主要原因。它产生有效的毒素，并引起浅表性病变，全身性疾病和多种毒物综合症。在这项研究中，我们确定了外排泵在耐甲氧西林金黄色葡萄球菌（MRSA）和耐甲氧西林金黄色葡萄球菌（MSSA）的生物膜中赋予对氟喹诺酮类药物耐药性的作用。我们选择的五种菌株的金黄色葡萄球菌，包括三个甲氧西林敏感菌株，包括ATCC25923，和耐甲氧西林的两种菌株小号。金黄色硫代哒嗪，氯丙嗪，羰基氰化物3-氯-苯基hydr和利血平对MSSA菌株具有活性。硫代哒嗪和氯丙嗪也对MRSA菌株具有活性。与对照菌株ATCC25923相比，硫代哒嗪和氯丙嗪的MSSA菌株2493和MRSA UC1079的生物膜形成显着减少。硫达达嗪对MSSA菌株N297214和MRSA菌株N307002表现出相似的作用。在这些菌株中，溴化乙锭，环丙沙星和莫西沙星的外排泵基因表达增加了四到八倍。但是，norB，norC，abcA和mepA的表达下降在MSSA和MRSA菌株中观察到了硫代哒嗪，氯丙嗪和柚皮苷。因此，这项研究表明，主要的促进子超家族，多药和毒素化合物的挤出以及外排泵的ATP结合盒家族在发展抗生素抗性和生物膜形成中起着至关重要的作用。这是关于MRSA和MSSA菌株中氟喹诺酮类药物除抗生素耐药性外生物膜中存在外排泵基因的第一份报告，这需要进一步表征。