Helicobacter pylori vacA genotypes, cagA status and ureA-B polymorphism in isolates recovered from an Argentine population.

Several reports have evidenced geographic differences in the prevalence of vacA (vacuolating cytotoxin gene) alleles and cagA (cytotoxin-associated gene) status among Helicobacter pylori isolates. We investigated the occurrence of these virulence-associated genes status among our isolates, and their relationship with ulcer disease outcome. Besides, ureA-B polymorphism was studied. One hundred isolates, comprising 32 from patients with ulcer disease (UD) and 68 from patients with non-ulcer dyspepsia (NUD), were analyzed. Eighty-four percent of isolates were cagA-positive without statistically significant difference in prevalence between patients with UD or NUD. Genotype vacA-s1m1 was predominant, although unlike other South American regions, subtype s1am1 occurrence was higher than s1b. The multivariate model used to estimate the predictive value of cagA and vacA status for UD development disclosed infection with vacA-s1am1 isolates as the only variable that increased the risk of UD onset. ureAB fingerprinting showed considerable genetic divergence among isolates, however, confirmed that certain DNA banding profiles are conserved worldwide.

[Epidemiologic consistency of polymerase chain reaction (PCR) based methods for the study of Acinotobacter baumannii infections]. / Concordancia epidemiológica de los métodos basados en la reacción en cadena de la polimerasa (PCR) para la investigación de las infecciones por Acinetobacter baumannii.

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.

Concordancia epidemiológica de los métodos basados en la reacción en cadena de la polimerasa (PCR) para la investigación de las infecciones por Acinetobacter baumannii. / [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.