| Background and objectivesAcinetobacter baumannii is a kind of non-fermenting Gram-negative bacilli. It is widely survive in the hospital environment and human skin, respiratory, gastrointestinal and urogenital tract. It can be an opportunistic pathogen in humans. Acinetobacter baumannii can survive for a long time in the hospital environment, and easily cause infection in critically ill patients. It is the common pathogenic bacteria of nosocomial infection. Compared with Pseudomonas, Acinetobacter baumannii is in a second place in the non-fermentative bacteria infection. Not only Acinetobacter baumannii is the major cause of respiratory infections, but also it can lead to ventilator-associated pneumonia, secondary meningitis, bacteremia, surgical site infections, urinary tract infections. Sputum and bronchial aspirate were the most important specimens for isolating Acinetobacter baumannii, followed were pus and secretions.The trend of resistance to common used antibiotics of Acinetobacter baumannii is increasing year by year. This phenomenon has been watched closely by microbiological and clinical scholars. ICU is the most common place for isolating Acinetobacter baumannii, the second is Respiratory Medicine. The Acinetobacter baumannii-infected patients are most from elderly patients, Critical illness and patients with poor body resistance, and the using of a variety of invasive medical procedures and long-term use of broad-spectrum antibiotics for patients. Conventional disinfection can inhibit their growth but not kill. The poor resistance or trauma patients may be infected from the hands of medical staff or incomplete disinfection of medical devices carried by Acinetobacter baumannii.The objective of this research was to analysis and statistics the Acinetobacter baumannii isolated trends and resistance to commonly used antibiotics in a general hospital in Zhengzhou from2009-2012. Meanwhile carbapenem resistance gene blaOXA-23were amplified by PCR, cloned and sequenced.MethodsThe samples of2009-2012were inoculated with the appropriate training methods, The clinically significant isolates were identified and wre tested for susceptibility by Vitek-2compact microbial identification system. The laboratory data of Acinetobacter baumannii were collected for4years.The isolated trend and the characteristics of antibiotics resistance of Acinetobacter baumannii were analyzed by Spass software from the various aspects of annual, quarterly, gender, age group, department, disease, and specimen source respectively.The carbapenem-resistant Acinetobacter baumannii were analyzed for the resistance to other antibiotics. Carbapenem resistance genes blaoxA-23were amplified by PCR for19carbapenem-resistant Acinetobacter baumannii and4carbapenem-sensitive Acinetobacter baumannii. The positive PCR products were cloned and DNA sequenced.The DNA sequences were made homology analysis with GenBank.Results1. The number of Acinetobacter baumannii isolated respectively were64,89,75and127for2009,2010,2011and2012, total of355. Accounting for pathogens ratios were2.21%,2.95%,2.41%and3.82%;2. Resistance rate:AMP, CZO, CXM, CXA, CTT, ATM and CRO were100%in four years; AMK is from1.6%to47.2%; Other antibiotics were over90%; Carbapenems were over92%.The various antibiotic resistance rates of2012were higher than other years. 3. The number of Acinetobacter baumannii isolated from quarter1,2,3, and4respectively were138,100,68and49;4. The numbers of male patients infected by Acinetobacter baumannii were about2times of female patients.5. The Acinetobacter baumannii isolated rate of61-100age group is the highest in all age groups.The antibiotics resistance rate of Acinetobacter baumannii of18-30group is higher than others.6. ICU accounted for67.04%for isolation rate of Acinetobacter baumannii, pulmonary medicine accounted for21.41%.The antibiotics resistance rates in ICU were higher than in pulmonary medicine.7. The resistance rate:TZP, IPM, MEM were high in respiratory failure;FEP is high in brain injury; CIP,LVX is high in stroke. All antibiotic resistance rates in pneumonia is lower than the other three diseases.8. There are323sputum samples for isolating Acinetobacter baumannii, accounting for90.99%of355specimens.9. Carbapenem-resistant Acinetobacter baumannii also has a high resistance rate to other antibiotics. The blaOXA-23genes are all positive for19carbapenem-resistant Acinetobacter baumannii, and are all negative for4carbapenem-sensitive Acinetobacter baumannii. Compared with GenBank AB849270, There are three blaOXA-23DNA sequences occurred T to A mutation at5985site in15blaOXA-23genes.ConclusionsThe isolation rate of Acinetobacter baumannii increased year by year; Winter and spring, older patients, ICU, and Pulmonary medicine were the important factors for high isolating Acinetobacter baumannii. Sputum is still the largest specimens for isolating Acinetobacter baumannii.The resistant rate to various antibiotics of Acinetobacter baumannii was growing year by year. The carbapenem-resistant Acinetobacter baumannii also have a very high resistance rates to other antibiotics. The blaOXA-23gene were found a mutation of T to A. |
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