Laboratory to Clinical Investigation of Carbapenem Resistant Acinetobacter baumannii Outbreak in a General Hospital

Abstract

Background:The number of reported cases, infected with carbepenem resistant Acinetobacter baumannii (CRAb) and multi-drug resistant (MDR) Acinetobacter species had gradually increased in most PLA general hospital wards from April to June in 2007.Objectives:We have described the investigation of an outbreak of CRAb and MDR Acinetobacter in PLA general hospital, Beijing. The prospective and retrospective findings were identified and analyzed to study the infection causes.Materials and Methods:A. baumannii samples were collected from the patients and environment in each hospital unit. The onset times were recorded according to their case information. All samples were characterized by genotype and compared using pulsed-field gel electrophoresis (PFGE). The microorganism susceptibility was tested using the in vitro minimal inhibitory concentration (MIC) breakpoints method.Results:A total of 69 A. baumannii strains were successfully isolated from 53 patients. About 89.1% of them were resistant to ampicillin and 89.2% to cefotaxime and 75.4% to all standard antibiotics. PFGE analysis revealed that nine of the isolates had unique clones and the epidemic clone types were A, B and C.Conclusions:The A. baumannii outbreak, was caused by MDR A. baumannii. The strains had widely spread among 12 departments especially in surgical intensive care unit (SICU), emergency intensive care unit (EICU) and the department of respiratory disease. The outbreak was more likely caused by the A. baumannii infected or carrier patients and EICU was its origin.

Distributions and Types of Multidrug-Resistant Acinetobacter baumannii in Different Departments of a General Hospital

“…Details are shown in Ref 6. Pseudomonas aeruginosa ATCC27853 and Escherichia coli ATCC25922 were used as the quality-control isolates ( 5 ).…”

“…It is also located on the skin of healthy human. Acinetobacter baumannii strains are able to survive for a long time even on a dry surface and some of them could toughly attach to human epithelial cells through fimbriae or side chains ( 5 ). These characteristics indicate that A. baumannii could easily spread via surface, air or any other possible pathways.…”

Epidemiological evaluation of an Acinetobacter baumannii outbreak observed at an intensive care unit

“…Ambrosi et al, 33 found 31 A. baumannii isolates grouped into 3 subtypes (A, B, and C). Guo-Xin et al, 29 found 62 A. baumannii isolates representing 9 different clones. Hammerun et al, 28 detected 4 different PFGE profiles in 8 investigated isolates and found 4 of the isolates were related to each other.…”

High Frequency of Class I and II Integrons and the Presence of aadA2 and dfrA12 Gene Cassettes in the Clinical Isolates of Acinetobacter baumannii from Shiraz, Southwest of Iran

“…Antimicrobial susceptibility patterns of the isolates were assessed using the Kirby-Bauer disk diffusion method on Mueller-Hinton Agar as described by the Clinical and Laboratory Standards Institute (CLSI) (12,13) guideline. All the isolates were sub-cultured from freezer stocks on sheep blood agar to prepare inoculum suspension.…”