J Korean Soc Microbiol.  1998 Dec;33(6):595-604.

Serological Typing of Acinetobacter baumannii Species

• Cho DT
• Cha HT
• Lee JC
• Lee JH

Abstract

In order to evaluate the efficiency of serological typing of A. baumannii in practical application, a total of 63 strains of A. baumannii and 234 strains of Gram-negative, lactose non-fermenting bacteria were tested with polyclonal rabbit immunized sera (RIS) against heat-killed A. baumannii strains by slide agglutination tests. Six typing sera of RIS were finally obtained after the checkerboard agglutination test and reciprocal cross-absorption. Species identification of sixty-three strains of A. baumannii were confirmed by ribotyping. Forty-seven (74.6%) of the 63 strains of A. baumannii showed strong positive reaction by slide agglutination tests. Thirty-nine strains could be serotypable and thus classified into 6 distinct serovars of A. baumannii, but 8 strains were unable to classify into specific serovar. Serovar 4 was the most frequent arbitrary serovar and included 17 strains among the 39. When slide agglutination tests were performed with 50-fold diluted pooled polyclonal RIS, there was no cross-reactions except one of E. coli strain among 234 strains of various Gram-negative lactose non-fermenting. Although each profile of LPS-gel electrophoresis of A. baumannii appeared to be unrelated with serovar, the patterns of western-blot of LPS after immunostaining with homologous RIS showed serovar-specificity. Several fractions of low molecular weight LPS showed cross-reaction with antisera of other serovars. In conclusion, the sensitivity and specificity of serological identification of A. baumannii strains were 74.6% and 99.6%, respectively. This result suggests that serotyping is a useful method for the identification of A. baumannii strains as well as is the epidemiological tool to trace back the source of the nosocomial outbreaks.

MeSH Terms

Acinetobacter baumannii*
Acinetobacter*
Agglutination Tests
Bacteria
Disease Outbreaks
Electrophoresis
Immune Sera
Lactose
Molecular Weight
Ribotyping
Sensitivity and Specificity
Serotyping
Immune Sera
Lactose