Pneumonia caused by extensive drug-resistant Acinetobacter baumannii among hospitalized patients: genetic relationships, risk factors and mortality

Abstract

BackgroundThe clonal spread of multiple drug-resistant Acinetobacter baumannii is an emerging problem in China. We analysed the molecular epidemiology of Acinetobacter baumanni isolates at three teaching hospitals and investigated the risk factors, clinical features, and outcomes of hospital-acquired pneumonia caused by extensive drug-resistant Acinetobacter baumannii (XDRAB) infection in Guangzhou, China.MethodsFifty-two A. baumannii isolates were collected. Multilocus sequence typing (MLST) was used to assess the genetic relationships among the isolates. The bla OXA-51-like gene was amplified using polymerase chain reaction (PCR) and sequencing. The resistance phenotypes were determined using the disc diffusion method. A retrospective case-control study was performed to determine factors associated with XDRAB pneumonia.ResultsMost of the 52 A. baumannii isolates (N = 37, 71.2%) were collected from intensive care units (ICUs). The respiratory system was the most common bodily site from which A. baumannii was recovered (N = 45, 86.5%). Disc diffusion classified the isolates into 17 multidrug-resistant (MDR) and 35 extensively drug-resistant (XDR) strains. MLST grouped the A. baumannii isolates into 5 existing sequence types (STs) and 7 new STs. ST195 and ST208 accounted for 69.2% (36/52) of the isolates. The clonal relationship analysis showed that ST195 and ST208 belonged to clonal complex (CC) 92. According to the sequence-based typing (SBT) of the bla OXA-51-like gene, 51 A. baumannii isolates carried OXA-66 and the rest carried OXA-199. There were no significant differences with respect to the resistance phenotype between the CC92 and non-CC92 strains (P = 0.767). The multivariate analysis showed that the APACHE II score, chronic obstructive pulmonary disease (COPD) and cardiac disease were independent risk factors for XDRAB pneumonia (P < 0.05). The mortality rate of XDRAB pneumonia was high (up to 42.8%), but pneumonia caused by XDRAB was not associated with in-hospital mortality (P = 0.582).ConclusionsST195 may be the most common ST in Guangzhou, China, and may serve as a severe epidemic marker. SBT of bla OXA-51-like gene variants may not result in sufficient dissimilarities to type isolates in a small-scale, geographically restricted study of a single region. XDRAB pneumonia was strongly related to systemic illnesses and the APACHE II score but was not associated with in-hospital mortality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2471-0) contains supplementary material, which is available to authorized users.

Etiology and characteristics of community-acquired pneumonia in an influenza epidemic period

“…The outbreak of A. baumannii infection is also associated with multidrug resistance, and carbapenems have been considered to be a major factor in resistance to multidrug-resistant A. baumannii infection [34]. Moreover, the mortality of carbapenem-resistant A. baumannii pneumonia patients is higher than that of carbapenem-sensitive A. baumannii pneumonia patients [35,36].…”

Epidemiology, Treatment, and Prevention of Nosocomial Bacterial Pneumonia

“…Many acquired insertion sequences or transposons have been shown to promote the over-expression, as well as spread of plasmid-associated bla OXA-58 genes in Acinetobacter species [30,34,35]. In addition, a higher point (≥4) of the Charlson co-morbidity index [34,35], a prolonged hospital stay (≥14 days) or an ICU stay (≥10 days) [36,37], a higher APACHE II score (≥16) [37] or Simplified Acute Physiology Score II [38], a recent receipt of broad-spectrum anti-bacterial agents, such as piperacillin-tazobactam, cefepime [39] or any carbapenem agent [37], were all reported to be associated with a predisposition of hospitalised patients to acquire XDR-A. baumannii complex pneumonia.…”

“…Stay at a unit where isolates of XDR-A. baumannii complex are highly prevalent [33] Charlson co-morbidity index ≥4 points [34,35] Prolonged (≥14-day) hospital stays, or ≥10-day ICU stays [36,37] A high APACHE II score (≥16) or Simplified Acute Physiology Score II [37,38] Prior receipt of cefepime, piperacillin-tazobactam, or carbapenem agents [37,39] ESBL-producing or carbapenem-resistant Enterobacteriaceae species…”

Real-time Utilization of Metagenomic Sequencing in the Diagnosis and Treatment Monitoring of an Invasive Adenovirus B55 Infection and Subsequent Herpes Simplex Virus Encephalitis in an Immunocompetent Young Adult

“…In our case, the patient also developed ventilation-associated nosocomial infection by a pan-drug-resistant A. baumannii and had to be treated with combination antibiotic therapy for a prolonged time (17 days). The high prevalence of nosocomial infections caused by this “superbug” highlights the urgency and challenges in ICUs in China, where much tighter infection prevention policies and enforcement are needed [11]. …”

“…Bronchoscopy showed an increased amount of purulent sputum, and the culture grew pan-drug-resistant (only susceptible to tigecycline) Acinetobacter baumannii , a common nosocomial pathogen circulating in many ICUs in China, including ours [11]. Piperacillin/tazobactam was then replaced by cefoperazone/sulbactam (1 g q6h) plus tigecycline (50 mg q12h).…”