Seasonal and Temperature-Associated Increase in Community-Onset Acinetobacter baumannii Complex Colonization or Infection

Identifying the trends in community-onset Acinetobacter baumannii complex isolation and diversity according to temperature could help provide insight into the behavior of the A. baumannii complex. We performed a retrospective analysis of A. baumannii complex (Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter pittii, and Acinetobacter calcoaceticus) isolates obtained from patients at a Korean community hospital from 2006 to 2015 with reference to seasonal temperatures. The incidence rates were compared between warm (June–September) and cold (November–March) months, defined as an average mean temperature ≥20℃ and ≤5℃, respectively. Incidence rate was calculated as the number of cases per month, converted to cases/10⁵ admissions for healthcare-acquired isolates and cases/10³ outpatients for community-onset isolates. Approximately 3,500 A. baumannii complex cases were identified, and 26.2% of them were community-onset cases. The median (interquartile range) number of community-onset A. baumannii complex cases was significantly higher (P=0.0002) in warm months at 13.8 (9.5–17.6) than in cold months at 10.1 (6.3–13.2). There was a strong correlation between community-onset A. baumannii complex cases and temperature (Pearson's r=0.6805, P=0.0149). Thus, we identified a seasonality pattern for community-onset A. baumannii complex colonization or infection, but not for healthcare-acquired cases.

The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

Abstract: INTRODUCTION: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. METHODS: Isolates identified over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. RESULTS: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like-positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. CONCLUSIONS: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

War trauma accompanied by multidrug-resistant infections: Recent progress / 第二军医大学学报

War trauma accompanied by multidrug-resistant infection pose a severe challenge for military medical services. Due to thewide application of antibiotics, war trauma complicated by multi-drug resistant infection is becoming a troublesome problem. This paper summarized the commonly-seen war-related bacteria and the corresponding revolution of drug resistance. The details of detection, treatment, and prevention measures of multi-drug resistant bacteria in war trauma were reviewed, and the risk factors of multi-drug resistance in warfare condition was also discussed.

In vitro antibacterial activity of tigecycline against carbapenems-resistant Acinetobacter calcoacetcus-Acinetobacter baumannii complex / 国际检验医学杂志

Objective To measure the in vitro antibacterial activity of tigecycline against carbapenems-resistant Acinetobacter calcoacetcus-Acinetobacter baumannii complex.Methods The isolated strains of carbapenems-resistant Acinetobacter calcoacetcus-Acinetobacter baumannii complex were collected in our hospital from December 2013 to February 2014.The MIC test strip was a-dopted to measure the MIC value of tigecycline.The break point adopted the judgment criteria published by FDA.Results All 61 strains of carbapenems-resistant Acinetobacter calcoacetcus-Acinetobacter baumannii complex had extremely high drug resistant rate to the commonly used antimicrobial agents.The sensitive rate of tigecycline was 80.3%,intermediation was 19.7% and no re-sistant strain was found in this study.MIC50 and MIC90 were 2 μg/mL and 3 μg/mL respectively.Conclusion Tigecycline has bet-ter in vitro antibacterial activity to the carbapenems-resistant Acinetobacter calcoacetcus-Acinetobacter baumannii complex isolated in our hospital.

Genospecies Classification of Acinetobacter calcoaceticus-Acinetobacter baumannii Complex by Restriction Fragment Length Polymorphism

Acinetobacter calcoaceticus-Acinetobacter baumannii (A. calcoaceticus-A. baumannii) complex, which includes A. calcoaceticus (genospecies 1), A. baumannii (genospecies 2), Acinetobacter genospecies 3 and 13, has been identified as A. baumannii by automated bacteria identification system. The purpose of this study is to develop rapid genospecies classification of A. calcoaceticus-A. baumannii complex by molecular techniques. Random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) were determined for 4 reference strains and 80 isolates of A. calcoaceticus-A. baumannii complex from clinical sources. Four and eleven RAPD patterns were observed among the reference strains and the isolates, respectively. RAPD might be useful for genomic typing but not for genospecies classification of Acinetobacter spp. RFLP of 16S-23S rRNA intergenic spacer gene with three selected restriction enzymes (ApaLI, SwaI, and SalI) showed only four RFLP patterns in the reference and the isolates. Of 80 isolates, 10 of A. calcoaceticus (12.5%), 50 of A. baumannii (62.5%), 11 of A. genospecies 3 (13.75%), and 9 of A. genospecies 13 (11.25%) were classified by RFLP. This result suggests that RFLP of 16S-23S rRNA intergenic spacer gene of A. calcoaceticus-A. baumannii complex might be useful for genospecies classification.