Epidemiologic concordance of polymerase chain reaction (PCR) based methodsfor the study of Acinetobacter baumannii infections.

Acinetobacter baumannii is one of the most frequent causative agents of nos ocomial infections outbreaks. Consequently, a rapid and specific typing met hod that can identify epidemic strains is important in preventing their dis semination. To evaluate PCR (polymerase chain reaction)-based methods as ep idemiological markers, epidemiologic concordance (EC) and the discriminator y power (D) of two of those methods: 1) arbitrary primed-PCR (AP-PCR), and 2) repetitive extragenic palindrome sequence-based PCR (REP-PCR), were anal yzed. The results were compared with that of ribotyping using EcoRI, Bgl II and C/aI as restriction enzymes. These methods were applied to 69 A. bauma nnii isolates that included: 15 epidemiological unrelated isolates, 31 reco vered from two outbreaks, and 23 obtained from endemic infections. Consider ing 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 r espect 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. Althou gh, the 3 methods identified the most frequent disseminated strain. The may or advantages of REP-PCR versus AP-PCR were reproducibility, and easier opt imization. These advantages, in addition to the similar EC of the 3 methods , confirm REP-PCR as an appropriate marker to be used when rapid informatio n about epidemiological A. baumannii infection analysis is required.