Currently, available phenotyping and commercial methods report <em>A. baumannii</em> only as <em>Acinetobacter calcoaceticus-baumannii</em> complex (ACB) and do not identify individual members ...Currently, available phenotyping and commercial methods report <em>A. baumannii</em> only as <em>Acinetobacter calcoaceticus-baumannii</em> complex (ACB) and do not identify individual members of the complex. This is a single blind study aimed to evaluate certain commonly used species-specific genetic markers namely, Intergenic Transcribed Spacer region in 16S rRNA of <em>A. baumannii</em> (Ab-ITS) and <em>gyrB</em>, for identification of ACB members. These molecular targets were first validated on clinical isolates (n = 200) and subsequently on uncultured tracheal aspirates (n = 172). Among the clinical isolates, 183/200 (91.5%) were positive for Ab-ITS. The clinical isolates 17 (17/200) which are failed to amplify in Ab-ITS PCR were subsequently diagnosed by <em>gyrB</em> PCR as <em>A. calcoaceticus</em> (n = 2), <em>A. pitti</em> (n = 6) and <em>A. nosocomialis</em> (n = 9) but not <em>A. baumannii</em>. Among the tracheal aspirates, 62 samples were reported as sterile in Advanced Expert System of VITEK-2, among the remaining 110 samples, 68.1% (75/110) samples contained Ab-ITS target. Twenty-five of the sterile samples (25/62) were found to contain Ab-ITS target sequence. Since, our sample processing method enabled identification of all the species of ACB complex by PCR even in uncultured tracheal aspirates, adaptation of our protocol would enable same day (6 - 8 h) reporting and help the clinician make evidence based therapeutic decision quickly.展开更多
文摘Currently, available phenotyping and commercial methods report <em>A. baumannii</em> only as <em>Acinetobacter calcoaceticus-baumannii</em> complex (ACB) and do not identify individual members of the complex. This is a single blind study aimed to evaluate certain commonly used species-specific genetic markers namely, Intergenic Transcribed Spacer region in 16S rRNA of <em>A. baumannii</em> (Ab-ITS) and <em>gyrB</em>, for identification of ACB members. These molecular targets were first validated on clinical isolates (n = 200) and subsequently on uncultured tracheal aspirates (n = 172). Among the clinical isolates, 183/200 (91.5%) were positive for Ab-ITS. The clinical isolates 17 (17/200) which are failed to amplify in Ab-ITS PCR were subsequently diagnosed by <em>gyrB</em> PCR as <em>A. calcoaceticus</em> (n = 2), <em>A. pitti</em> (n = 6) and <em>A. nosocomialis</em> (n = 9) but not <em>A. baumannii</em>. Among the tracheal aspirates, 62 samples were reported as sterile in Advanced Expert System of VITEK-2, among the remaining 110 samples, 68.1% (75/110) samples contained Ab-ITS target. Twenty-five of the sterile samples (25/62) were found to contain Ab-ITS target sequence. Since, our sample processing method enabled identification of all the species of ACB complex by PCR even in uncultured tracheal aspirates, adaptation of our protocol would enable same day (6 - 8 h) reporting and help the clinician make evidence based therapeutic decision quickly.
