Biofilm formation and dispersal of Staphylococcus aureus under the influence of oxacillin
Biofilm formation and dispersal of Staphylococcus aureus under the influence of oxacillin
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DOI：
10.1016/j.micpath.2013.05.002
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发表时间：
2013-08-01
影响因子：
3.8
通讯作者：
Khan, Seema Ismat
中科院分区：
文献类型：
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作者：
Mirani, Zulfigar Ali;Aziz, Mubashir;Khan, Seema Ismat
本研究使用了总计180株食源性耐甲氧西林金黄色葡萄球菌（MRSA）分离株（苯唑西林MIC 864 μ g/ml），以研究苯唑西林对生物膜形成及其脱落过程的影响。绝大多数菌株（98.3%）携带icaA基因。在180株分离株中，35.5%为MRSA，64.4%为甲氧西林敏感的S。金黄色葡萄球菌（MSSA）。生物膜的研究显示，57%的MRSA分离株是生物膜生产者。聚合酶链反应研究表明，所有的生物膜阳性MRSA分离株属于SCCmec IV型和携带agr II型。这表明SCCmec IV agr II型与食源性MRSA中的生物膜形成密切相关。相反，只有13.7%的MSSA分离株是生物膜阳性，大多数被发现携带AGR II型。苯唑西林对icaA的表达具有调节作用，可诱导依赖icaA的多糖细胞内粘附素（PIA）的产生和生物膜的形成。MRSA和MSSA分离株的真实的时间PCR研究证实了这一点。定量分析表明，大多数MRSA分离株在亚抑菌浓度的苯唑西林存在下孵育24 h后开始形成生物膜，并在48 h后在载玻片上达到最高粘附。不存在苯唑西林的对照显示出生长模式从增殖型向生物膜模式的缓慢转化（表1）。大多数这些产生生物膜的分离株的另一个新特征是（光密度）OD的降低，这在孵育48小时后被注意到。可能地，在苯唑西林失去其毒性或消耗48小时后，细胞可能通过辅助基因调节因子A（agrA）的激活重新适应强直状态，所述辅助基因调节因子A在生物膜分散中具有重要作用。(C)2013爱思唯尔有限公司保留所有权利。
A total of 180 food borne isolates of methicillin resistant Staphylococcus aureus (MRSA) (oxacillin MICs 864 mu g/ml) were used in the present study to investigate the effect of oxacillin on biofilm formation and its detachment process. Majority (98.3%) of these isolates were found to carry icaA gene. Out of 180 isolates 35.5% were identified as MRSA and 64.4% were methicillin sensitive S. aureus (MSSA). Biofilm studies by con-red agar and tube methods revealed that 57% of the MRSA isolates were biofilm producers. Polymerase chain reaction studies suggested that all of the biofilm positive MRSA isolates belong to SCCmec type IV and carry agr type II. This showed the strong association of SCCmec IV agr type II and biofilm formation in food borne MRSA. Conversely, only 13.7% of the MSSA isolates were biofilm positive and majority was found to carry agr type II. It has been noticed that oxacillin has regulatory effect on icaA expression and induce the icaA dependent polysaccharide intracellular adhesin (PIA) production and biofilm formation. This was confirmed by Real Time PCR studies of MRSA and MSSA isolates. Quantitative analysis showed that most of the MRSA isolates started biofilm formation after 24 h of incubation in the presence of sub-inhibitory concentration of oxacillin and achieved highest adhesion on glass slide after 48 h. The control in the absence of oxacillin showed slow conversion from planktonic to biofilm mode of growth (Table 1). Another novel feature of most of these biofilm producing isolates is the reduction in (Optical Density) OD, which is noticed after 48 h of incubation. Possibly, after 48 h oxacillin loses its toxicity or consumed the cells re-adapt to the planktonic state, possibly, by the activation of accessory gene regulator A (agrA) which has an important role in biofilm dispersal. (C) 2013 Elsevier Ltd. All rights reserved.