Liaqat Iram, Sabri Anjum Nasim
Department of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus Lahore, Pakistan.
J Basic Microbiol. 2009 Jun;49(3):275-84. doi: 10.1002/jobm.200800212.
Six biocides resistant isolates were isolated from dental unit water lines (DUWL) in Pakistan. All isolates could tolerate 150 microg ml(-1 )of biocides (5.25% sodium hypocholrite, 35% H2O2, 4% tween 20, 1% povidine iodine, 0.2% chlorohexidine gluconate, 1% ethylene di-amino tetra acetic acid and 1% phenol) on l-agar and 100 microg ml(-1 )in l-broth. The growth rate of all isolates was determined by generating growth curves at 37 degrees C for 48 h. The isolates were found to differ in growth rates with lag phase varying from (4-6 h) in biocides supplemented media compared to 2-4 h in biocides free medium. They have wide temperatures (24-42 degrees C) and pH (5-9) ranges. Traditional ways of identification of bacteria by phenotypic characteristics were accomplished by phenotypic and biochemical characterization. Heavy metals and antimicrobial susceptibility tests indicated that all isolates examined were resistant to trimethoprim, chloramphenicol while sensitive to HgCl2 and Pb (NO3)2. Almost all isolates were opportunistic pathogens. The 16S rRNA-encoding genes from these six isolates were sequenced to confirm the identity of these isolates. 5 different genera (Bacillus, Achromobacter, Pseudomonas and Klebsiella) of bacteria were identified by 16S rDNA genes amplified from genomic DNA of biocides resistant DUWL biofilm isolates. Analysis of 16S rDNA genes revealed a much more clear identification of microorganisms than culture methods. However, different species of the same genera can have the same 16S rRNA gene sequence but are different due to phenotypic differences or different clinical manifestations.
在巴基斯坦，从牙科设备水线（DUWL）中分离出了6株具有生物杀灭剂抗性的菌株。所有分离株在L-琼脂上能够耐受150微克/毫升的生物杀灭剂（5.25%次氯酸钠、35%过氧化氢、4%吐温20、1%聚维酮碘、0.2%葡萄糖酸氯己定、1%乙二胺四乙酸和1%苯酚），在L-肉汤中能够耐受100微克/毫升。通过在37℃下培养48小时绘制生长曲线来测定所有分离株的生长速率。结果发现，与不含生物杀灭剂的培养基相比，在添加生物杀灭剂的培养基中，分离株的生长速率不同，延迟期从4至6小时不等，而在不含生物杀灭剂的培养基中为2至4小时。它们具有较宽的温度范围（24至42℃）和pH范围（5至9）。通过表型和生化特征完成了通过表型特征鉴定细菌的传统方法。重金属和抗菌药敏试验表明，所有检测的分离株对甲氧苄啶、氯霉素耐药，而对氯化汞和硝酸铅敏感。几乎所有分离株都是机会致病菌。对这6株分离株的16S rRNA编码基因进行测序以确认这些分离株的身份。通过从具有生物杀灭剂抗性的DUWL生物膜分离株的基因组DNA中扩增16S rDNA基因，鉴定出了5个不同属（芽孢杆菌属、无色杆菌属、假单胞菌属和克雷伯菌属）的细菌。16S rDNA基因分析显示，与培养方法相比，对微生物的鉴定要清晰得多。然而，同一属的不同物种可能具有相同的16S rRNA基因序列，但由于表型差异或不同的临床表现而有所不同。
