Evolution of antimicrobial resistance of Acinetobacter baumannii in a university hospital

Aims: To investigate the susceptibility pattern and the molecular epidemiology of Acinetobacter baumannii isolates in two periods (1994–1996 and 2004–2007) in Londrina University Hospital. Methods and Results: Antimicrobial susceptibility of 150 A. baumannii isolates was assessed by disc diffusion and agar dilution methods. Genetic similarity amongst the isolates was evaluated by ERIC–PCR. Resistance of A. baumannii to carbapenems increased from 2% (1994–1996) to 73% (2004–2007). Thirty‐eight clones were detected. Conclusions: The results of the study suggest that the high prevalence of carbapenem resistance amongst Acinetobacter baumannii organisms in this institution is not caused by the spread of a predominant clone. Significance and Impact of the Study: This work reinforces the importance monitoring antimicrobial susceptibility rates.     

心内科患者医院感染鲍氏不动杆菌的耐药性分析

目的了解心内科住院患者医院感染鲍氏不动杆菌的耐药性,为指导临床合理用药提供依据。方法从2010—2012年心内科住院患者送检标本中分离鲍氏不动杆菌,采用PHOENIX-100全自动细菌鉴定药敏系统进行细菌鉴定及药敏试验,并对结果进行统计分析。结果2010-2012年心内科住院患者共分离出166株鲍氏不动杆菌,其中泛耐药菌株34株,检出率为20．5％。药敏结果显示鲍氏不动杆菌对常用抗菌药物的耐药率呈逐年上升趋势,并显示出多重耐药性,对多粘菌素B、头孢哌酮／舒巴坦、亚胺培南和美罗培南等耐药率相对较低。结论鲍氏不动杆菌已成为医院感染重要病原菌,对多种抗菌药物耐药,临床应加强耐药性监测,根据药敏结果合理选用抗菌药物,以控制医院感染的暴发流行。     

连续11年深圳地区鲍曼不动杆菌感染的临床分布及耐药趋势分析

目的 了解医院鲍曼不动杆菌的耐药性变迁和临床分布特点,为合理应用抗菌药物和预防控制医院感染提供依据.方法 回顾性分析2001年1月到2011年12月临床标本中分离的l 613株鲍曼不动杆菌资料;用WHONET 5.4分析鲍曼不动杆菌的分离率和耐药率变迁.结果 鲍曼不动杆菌感染主要发生在ICU和呼吸内科,分别占43.89％和24.49％;痰标本所占比例最高(70.30％).鲍曼不动杆菌、多药耐药鲍曼不动杆菌的分离率及对临床常用的15种抗菌药物耐药率总体呈上升趋势;并且2009年呈飞跃式上升且2010和2011年居高不下,201 1年分离出泛耐药鲍曼不动杆菌,分离率高达57.55％.临床常用药氨苄西林/舒巴坦、头孢哌酮/舒巴坦和米诺环素近三年的耐药率和中介率也明显升高.结论 鲍曼不动杆菌的耐药形势严峻,多药耐药鲍曼不动杆菌和泛耐药鲍曼不动杆菌比例明显增加,重症监护病房和呼吸科是预防控制的重点科室.     

The cost of resistance to colistin in Acinetobacter baumannii: a proteomic perspective

Colistin resistance in Acinetobacter baumannii, a pathogen of clinical concern, was induced in the susceptible strain ATCC 19606 by growth under increasing pressure of the antibiotic, the only drug universally active against multi‐resistant clinical strains. In 2‐D difference gel electrophoresis (DIGE) experiments, 35 proteins with differences in expression between both phenotypes were identified, most of them appearing as down regulated in the colistin‐resistant strain. These include outer membrane (OM) proteins, chaperones, protein biosynthesis factors, and metabolic enzymes, all suggesting substantial loss of biological fitness in the resistant phenotype, as substantiated by complementary experiments in the absence of colistin. Results shed light on the scarcity of widespread clinical outbreaks for resistant phenotypes.     

Species distribution,virulence factors and antimicrobial resistance of Acinetobacter spp. isolates from dogs and cats: a preliminary study

In this study, the prevalence of virulence factors and antimicrobial resistance among 67 Acinetobacter spp. isolates, consisting of 21 Acinetobacter baumannii and 46 non‐baumannii Acinetobacter obtained from companion animals, was investigated. PCR analysis showed that the most prevalent virulence gene was afa/draBC (29.9%), followed by papC (22.4%) and cvaC (20.9%). Antimicrobial susceptibility testing revealed that resistance to gentamicin (14.9%) and ciprofloxacin (11.9%) was relatively prevalent. Five gentamicin‐ and/or ciprofloxacin‐resistant A. baumannii strains were assigned to ST25, ST149, ST164, ST203 and ST1198. All ciprofloxacin‐resistant isolates harbored point mutations in gyrA and/or parC. To the best of our knowledge, this is the first report of preliminary monitoring of animal‐origin Acinetobacter spp. in Japan.

     

Acinetobacter baumannii as a community foodborne pathogen: Peptide mass fingerprinting analysis,genotypic of biofilm formation and phenotypic pattern of antimicrobial resistance

Acinetobacter baumannii (A. baumannii) is one of the most common Gram-negative pathogens that represent a major threat to human life. Because the prevalence of Multidrug-resistant biofilm-forming A. baumannii is increasing all over the world, this may lead to outbreaks of hospital infections. Nonetheless, the role of raw meat as a reservoir for A. baumannii remains unclear. Here our research was aimed to exhibit the frequency, precise identification, and genotyping of biofilm-related genes as well as antimicrobial resistance of A. baumannii isolates of raw meat specimens. Fifty-five A. baumannii strains were recovered from 220 specimens of different animal meat and then identified by Peptide Mass Fingerprinting Technique (PMFT). All identified isolates were genotyped by the qPCR method for the existence of biofilm-related genes (ompA, bap, blaPER-1, csuE, csgA, and fimH). In addition, the antimicrobial resistance against A. baumannii was detected by the Kirby-Bauer method. Based on our findings, the frequency rate of 55 A. baumannii isolates was 46.55%, 32.50%, 15.00%, and 9.68% of sheep, chicken, cow, and camel raw meat samples, respectively. The PMFT was able to identify all strains by 100%. the percentages of csuE, ompA, bla_PER-1, bap, and csgA genes in biofilm and non-biofilm producer A. baumannii were 72.73%, 60%, 58.2%, 52.74%, and 25.45%, respectively. In contrast, the fimH was not detected in all non-biofilm and biofilm producer strains. The ompA, bap, blaPER-1, csgA were detected only in biofilm-producing A. baumannii isolates. The maximum degree of resistance was observed against amoxicillin/clavulanic acid (89.10%), gentamicin (74.55%), tetracycline (72.73%), ampicillin (65.45%), and tobramycin (52.73%). In conclusion, our investigation demonstrated the high incidence of multi-drug resistant A. baumannii in raw meat samples, with a high existence of biofilm-related virulence genes of ompA, bap, blaPER-1, csgA. Therefore, it has become necessary to take the control measures to limit the development of A. baumannii.     

Selection for starvation resistance in Drosophila melanogaster : physiological correlates,enzyme activities and multiple stress responses

Correlated responses to artificial selection for stress tolerance can provide insight into underlying genetic variation and the physiological basis of stress resistance . Lines of Drosophila melanogaster held in the absence of food or with an unsuitable resource, specifically decomposing lemon, responded to selection by becoming starvation resistant. The lemon-selected lines also adapted by evolving a resource-based induction response. Compared to control lines, the selected lines tended to store more lipid, develop slower and have a larger body size. Additional responses included resistance to desiccation and acetone fumes, suggesting multiple stress resistance is a correlated result of selection for starvation resistance. The specific metabolic rate was lower in the starvation selected lines and enzyme activities changed in response to selection. In particular, enzyme activities indirectly associated with lipid biogenesis increased in both types of selected lines. The correlated responses to the two selection regimes were sufficiently consistent to indicate a common basis for starvation resistance. Specific responses to starvation selection appeared to oppose the short-term phenotypic responses to starvation. Thus, a common response to stress selection may be to ameliorate the immediate physiological impact of the stress factor.