Rao R Srinivasa, Karthika R Uma, Singh S P, Shashikala P, Kanungo R, Jayachandran S, Prashanth K
Department of Biotechnology, School of Life Sciences, Pondicherry University, R. Venkataraman Nagar, Kalapet, Puducherry, India.
Indian J Med Microbiol. 2008 Oct-Dec;26(4):333-7. doi: 10.4103/0255-0857.43566.
To study the qualitative and quantitative methods for the investigation of biofilm formation and to examine the correlation between biofilm and antibiotic resistance among the clinical isolates of Acinetobacter baumannii . We also verified the association between biofilm and presence of extended spectrum beta-lactamases, particularly, bla PER-1 .
A total of 55 isolates were subjected to susceptibility testing by disc diffusion method for 13 clinically relevant antibiotics. Screening for biofilm production was done by both qualitative and quantitative methods through tube and microtitre plate assay respectively. The presence of bla PER-1 was checked by PCR.
A. baumannii isolates showed very high resistance (>75%) to imipenem, cephotaxime, amikacin and ciprofloxacin. Only cefoperazone, netillin and norfloxacin were found to be effective agents. Results of microtitre and tube methods were concordant with 34 isolates (62%) showing biofilm formation. Resistance to four antibiotics such as amikacin (82% vs. 17.6%, P < 0.001), cephotaxime (88% vs. 11%, P P < 0.001), ciprofloxacin (70% vs. 29%, P =0.005) and aztreonam (38% vs. 11%, P =0.039) was comparatively higher among biofilm producers than non-biofilm producers. Microtitre assay additionally detected 14 weakly adherent isolates. Only 11 isolates had bla PER-1 gene and among these two were strong biofilm producers, while remaining were weakly adherent isolates.
Microtitre plate method was found to be a more sensitive method for biofilm detection. This study demonstrates a high propensity among the clinical isolates of A. baumannii to form biofilm and a significant association of biofilms with multiple drug resistance. Presence of bla PER-1 appears to be more critical for cell adherence than for biofilm formation.
研究生物膜形成的定性和定量检测方法，并检测鲍曼不动杆菌临床分离株中生物膜与抗生素耐药性之间的相关性。我们还验证了生物膜与超广谱β-内酰胺酶（尤其是bla PER-1）存在之间的关联。
采用纸片扩散法对55株分离株进行13种临床相关抗生素的药敏试验。分别通过试管法和微量滴定板法，采用定性和定量方法筛选生物膜的产生情况。通过聚合酶链反应（PCR）检测bla PER-1的存在情况。
鲍曼不动杆菌分离株对亚胺培南、头孢噻肟、阿米卡星和环丙沙星显示出非常高的耐药性（>75%）。仅发现头孢哌酮、奈替米星和诺氟沙星是有效的抗菌药物。微量滴定板法和试管法的结果一致，34株（62%）分离株显示有生物膜形成。生物膜形成菌对阿米卡星（82%对17.6%，P<0.001）、头孢噻肟（88%对11%，P<0.001）、环丙沙星（70%对29%，P=0.005）和氨曲南（38%对11%，P=0.039）等四种抗生素的耐药性明显高于非生物膜形成菌。微量滴定板法还检测到14株弱黏附性分离株。只有11株分离株具有bla PER-1基因，其中两株是强生物膜形成菌，其余是弱黏附性分离株。
微量滴定板法被发现是一种更敏感的生物膜检测方法。本研究表明，鲍曼不动杆菌临床分离株形成生物膜的倾向很高，且生物膜与多重耐药性之间存在显著关联。bla PER-1的存在似乎对细胞黏附比对生物膜形成更为关键。
