Patwardhan R B, Dhakephalkar P K, Niphadkar K B, Chopade B A
Department of Microbiology, University of Pune, Pune, India.
Indian J Med Res. 2008 Aug;128(2):178-87.
BACKGROUND & OBJECTIVES: Antibiotic resistant bacterial nosocomial infections are a leading problem in intensive care units (ICU). Present investigation was undertaken to know antibiotic resistance in Acinetobacter baumannii and some other pathogens obtained from clinical samples from ICU causing nosocomial infections. Special emphasis was given on plasmid mediated transferable antibiotic resistance in Acinetobacter.
The clinical specimens obtained from ICU, were investigated to study distribution of nosocomial pathogens (272) and their antibiotic resistance profile. Acinetobacter isolates were identified by API2ONE system. Antimicrobial resistance was studied with minimum inhibitory concentration (MIC) by double dilution agar plate method. The plasmid profile of 26 antibiotic resistant isolates of Acinetobacter was studied. Curing of R-plasmids was determined in three antibiotic resistant plasmid containing A. baumannii isolates. Plasmid transfer was studied by transformation.
Major infections found in ICU were due to Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes. The infection rate was maximum in urinary tract (44.4%) followed by wound infections (29.4%), pneumonia (10.7%) and bronchitis (7.4%). Acinetobacter isolates displayed high level of antibiotic resistance (up to 1024microg/ml) to most of antibiotics. More than 90 per cent isolates of Acinetobacter were resistant to a minimum of 23 antibiotics. Plasmid profile of Acinetobacter isolates showed presence of 1-4 plasmids. Ethidium bromide cured plasmids pUPI280, pUPI281, pUPI282 with curing efficiencies 20, 16 and 11 per cent respectively while acridine orange cured plasmids pUPI280, pUPI281 with curing efficiencies 7 and 18 per cent retrospectively. Transformation frequency of E. coli HB101 with pUPI281 was 4.3 x 10(4) transformants/microg plasmid DNA.
INTERPRETATION & CONCLUSIONS: A. baumannii was found to be associated with urinary tract infections, respiratory tract infections, septicaemia, bacteraemia, meningitis and wound infections. A. baumannii displayed higher resistance to more number of antibiotics than other nosocomial pathogens from ICU. Antibiotic sensitivity of A. baumannii cured isolates confirmed plasmid borne nature of antibiotic resistance markers. Transfer of antibiotic resistant plasmids from Acinetobacter to other nosocomial pathogens can create complications in the treatment of the patient. Therefore, it is very important to target Acinetobacter which is associated with nosocomial infections.
耐抗生素的细菌医院感染是重症监护病房（ICU）中的一个主要问题。本研究旨在了解鲍曼不动杆菌及其他一些从ICU临床样本中分离出的导致医院感染的病原体的抗生素耐药情况。特别关注了鲍曼不动杆菌中质粒介导的可转移抗生素耐药性。
对从ICU获取的临床标本进行研究，以了解医院病原体（272株）的分布及其抗生素耐药谱。采用API2ONE系统鉴定不动杆菌分离株。通过双倍稀释琼脂平板法，以最低抑菌浓度（MIC）研究抗菌药物耐药性。研究了26株耐抗生素的不动杆菌分离株的质粒图谱。在三株含有抗生素耐药质粒的鲍曼不动杆菌分离株中测定R质粒的消除情况。通过转化研究质粒转移。
在ICU中发现的主要感染是由鲍曼不动杆菌、大肠杆菌、肺炎克雷伯菌、铜绿假单胞菌、金黄色葡萄球菌和化脓性链球菌引起的。感染率最高的是尿路感染（44.4%），其次是伤口感染（29.4%）、肺炎（10.7%）和支气管炎（7.4%）。不动杆菌分离株对大多数抗生素表现出高水平的耐药性（高达1024μg/ml）。超过90%的不动杆菌分离株对至少23种抗生素耐药。不动杆菌分离株的质粒图谱显示存在1 - 4个质粒。溴化乙锭消除质粒pUPI280、pUPI281、pUPI282的效率分别为20%、16%和11%，而吖啶橙消除质粒pUPI280、pUPI281的效率分别为7%和18%（回顾性数据）。用pUPI281转化大肠杆菌HB101的转化频率为4.3×10⁴转化子/μg质粒DNA。
发现鲍曼不动杆菌与尿路感染、呼吸道感染、败血症、菌血症、脑膜炎和伤口感染有关。与ICU中的其他医院病原体相比，鲍曼不动杆菌对更多种类的抗生素表现出更高的耐药性。对鲍曼不动杆菌消除质粒后的分离株进行抗生素敏感性测试，证实了抗生素耐药标记的质粒携带性质。抗生素耐药质粒从不动杆菌转移到其他医院病原体可能会给患者治疗带来并发症。因此，针对与医院感染相关的鲍曼不动杆菌非常重要。
