Epidemiologic consistency of polymerase chain reaction (PCR) based methods for the study of Acinotobacter baumannii infections

Acinetobacter baumannii is one of the most frequent causative agents of nosocomial infections outbreaks. Consequently, a rapid and specific typing method that can identify epidemic strains is important in preventing their dissemination. To evaluate PCR (polymerase chain reaction)-based methods as epidemiological markers, epidemiologic concordance (EC) and the discriminatory power (D) of two of those

Methods: 1) arbitrary primed-PCR (AP-PCR), and 2) repetitive extragenic palindrome sequence-based PCR (REP-PCR), were analyzed. The results were compared with that of ribotyping using EcoRI, BglII and ClaI as restriction enzymes. These methods were applied to 69 A. baumannii isolates that included: 15 epidemiological unrelated isolates, 31 recovered from two outbreaks, and 23 obtained from endemic infections. Considering the unrelated isolates, D of ribotyping, AP-PCR and REP-PCR were 0.915, 0.904 and 0.847, respectively. The three methods showed the same EC with respect to the two analyzed outbreaks (100% and 83%, respectively), and the epidemic strains were uniformi differentiated from the co-transferred ones. Ribotyping classified the 23 isolates recovered from endemic infections in 4 different strains, while AP-PCR and REP-PCR identified 3 of them. Although, the 3 methods identified the most frequent disseminated strain. The mayor advantages of REP-PCR versus AP-PCR were reproducibility, and easier optimization. These advantages, in addition to the similar EC of the 3 methods, confirm REP-PCR as an appropriate marker to be used when rapid information about epidemiological A. baumannii infection analysis is required.