Discrimination of epidemic and sporadic isolates of Acinetobacter baumannii by repetitive element PCR-mediated DNA fingerprinting

Abstract

In 1990, there was a significant increase in the number of lower respiratory tract infections and surgical wound infections in the adult intensive care units of our tertiary care teaching hospital caused by Acinetobacter baumannii compared with the number in 1989. During the 5-month period from April through August 1990, 84 isolates ofA. baumannii were recovered from 50 hospitalized patients. Biotyping, comparison of antibiograms, plasmid analysis, and DNA polymorphisms of 20 isolates from 20 different patients, determined by the use of repetitive element PCR with primers aimed at repetitive extragenic palindromic sequences and enterobacterial repetitive intergenic consensus sequences, were used to investigate this apparent outbreak Biotyping, antibiograms, plasmid analysis, and enterobacterial repetitive intergenic consensus PCR were not useful epidemiologically. Repetitive element PCR-mediated DNA fingerprinting using repetitive extragenic palindromic primers discriminated between epidemic and sporadic strains ofA. baumannii and demonstrated four discrete clusters which were unique epidemiologically. Acinetobacter baumannii (4) or Acinetobacter calcoaceticus-Acinetobacter baumannii complex (17) (formerly classified as A. calcoaceticus subsp. anitratus) is a nonfermentative, aerobic gram-negative bacillus that is ubiquitous in the environment and found commonly as part of the normal flora of humans (3, 41). It has been reported with increasing frequency in sporadic outbreaks of nosocomial infections, often in association with contamination of hospital equipment or colonization on the hands of health care workers (6, 7, 25, 27, 33, 34, 37). The most frequent site of infection with A. baumannii is the lower respiratory tract (6). Urinary tract infections, wound infections, and bacteremia are also common (13, 19, 26, 35, 37). Although several methods have been used for typing of Acinetobacter strains, including biotyping, bacteriocin typing, serotyping, and phage typing, comparison of antibiograms, whole cell and cell envelope protein profiles, enzyme profiles, plasmid analysis, ribotyping, and determination of DNA restriction fragment length polymorphisms by pulsed-field gel electrophoresis, there is no generally accepted typing scheme for epidemiologic studies of this organism (1, 2, 5, 9, 10, 17, 21, 24, 29, 42, 46). Recently, PCR fingerprinting using a single primer derived from the core sequence of phage M13 was applied to characterizeA. baumannii isolates from an outbreak in an anesthesiologic intensive care unit (ICU) (22). Compared with other DNA-based strain identification methods, PCR fingerprinting was found to be simple and rapid and effectively demonstrated strain discrimination (22). Hahnemann University Hospital is a 630-bed tertiary care teaching hospital. In 1990, there was a significant increase in the number of lower respiratory tract infections and surgical wound infections in the adult ICUs caused by A. baumannii compared with 1989 numbers. In 1990, 54 of 472 lower

High resolution DNA fingerprinting of Acinetobacter outbreak strains

“…In addition, Acinetobacter type strains CCUG 19096T, ATCC 19004T, and ATCC 17903T of DNA groups 2, 3, and 13TU, respectively, were included in the numerical analysis and linked with the various outbreaks at an average similarity of approx. [15,16], and PCR fingerprinting [17][18][19]. Compared to these methods, AFLP is perhaps more laborious and requires special equipment.…”

Validation of use of whole-cell repetitive extragenic palindromic sequence-based PCR (REP-PCR) for typing strains belonging to the Acinetobacter calcoaceticus-Acinetobacter baumannii complex and application of the method to the investigation of a hospital outbreak

“…Variations in the intensity or shape of bands were not taken into account. The absence of up to two bands from a fingerprint was allowed, when all other visible bands in the fingerprints matched, before isolates were considered different by visual inspection (30,41).…”

“…The highly conserved REP sequence is approximately 35 nucleotides long, includes an inverted repeat, and can occur in the genome singly or as multiple adjacent copies (36). Recently, Reboli et al (30) described the use of REP-PCR to characterize isolates of A. baumannii from hospitalized patients. The method effectively discriminated between epidemic and sporadic isolates but required time-consuming genomic DNA isolation, purification, and quantitation.…”

Epidemiological study of Acinetobacter species isolated from an intensive care unit

“…(i) Acinetobacter baumunnii strain no. (biotype proposed by Bouvet & Grimont, 1987) 50853-82 (2), R1093 (5)-M91 (6), ATCC 17922 (8), ATCC 17904 (9), ATCC 9955 (12), AB 2445 (14), R112 (16), M147 (18), R466 (19).…”

“…Many methods have been used to type Acinetobacter strains, including serotyping (28), bacteriocin typing (2), cell envelope protein profiling (7), biotyping (3, 5-7, 9, 17, 23, 27), antibiograms (7,9,17,18), plasmid profiling (16, 17,20,21), ribotyping (3,7,8,10,23), genomic macrorestriction analysis (1, 12,18,21,22,24,25), and PCR (13,18,19,24). At present, there is no generally accepted typing method which can be used alone.…”