SXT constin among Vibrio cholerae isolates from a tertiary care hospital.

Background & objectives: The SXT element, also known as ‘constin’ (conjugable, self transmissible, integrating element) is an integrating conjugative element (ICE) in Vibrio cholerae discovered in the chromosome of epidemic V. cholerae O139 strain MO10 (SXTMO10) which arose in late 1992 in Chennai, India. SXT related ICEs have become widespread and currently, most if not all Asian V. cholerae clinical isolates contain SXT related ICEs. The present study attempts to determine the presence of SXT Int gene in V. cholerae recovered between 2005 to 2007 in a tertiary care hospital, demonstrate its conjugal nature and also detect co-presence and co-transfer of plasmids in representative isolates. Methods: This prospective study was done on 116 V. cholerae isolates [114- O1 (107 ogawa and 7 inaba) and 2 - Non O1 Non O139 V. cholerae] from watery stools between 2005 to 2007 recovered from equal number of patients. PCR was carried out using SXT Int specific primers that produced a 592 bp internal fragment of SXT element, and rifampicin resistant strain of E.coli K-12 was used as recipient in conjugation experiments to study transfer of SXT, as also co-transfer of resistance to tetracycline, erythromycin, and nalidixic acid. Antibiotic susceptibility was performed against various antibiotics. Results: Of the 116 isolates, 110 (94.8%) were positive for SXT element by PCR. It was demonstrated in 94.7 per cent of the O1, and 100 per cent of non O1 non O139 V. cholerae. All 2005 isolates, 25 per cent of 2006 isolates and 96.6 per cent of 2007 isolates were positive for SXT. Thirty two drug resistance patterns were observed and the 2007 isolates showed resistance to as many as eight antibiotics. The resistance of SXT positive isolates was higher than those of SXT negative and the typical drug resistance pattern corresponding to SXTET and SXTMO10 was shown by only one V. cholerae O1 isolate. Successful conjugal transfer of SXT was seen in 31 (88.6%) of the 35 isolates studied without any co-transfer while, presence of plasmids was observed in two of the 31 donor V. cholerae studied. Interpretation & Conclusions: The demonstration of SXT element and its successful horizontal transfer in V. cholerae isolates studied emphasizes the need for its detection to monitor antibiotic resistance and dissemination in V. cholerae.

Isolation of mycobacterium avium complex and M Simiae from blood of AIDS patients from Sevagram, Maharashtra.

Background and Methodolgoy: Mycobacterium avium complex (MAC) has not been reported as an opportunistic pathogen among patients with AIDS in the Indian subcontinent. Blood samples were cultured for mycobacteria using BACTEC 460TB system from 71 HIV seropositive and 33 seronegative patients, tested at Mahatma Gandhi Institute of Medical Sciences, Sevagam between August 2001 and December 2002. Results: MAC and M. simiae were isolated from three patients each. All the six patients with mycobacteremia were AIDS cases. Clinically, none of them was diagnosed as a case of mycobacteremia. However, laboratory results confirmed the dissemination of MAC and M. simiae among these patients. Conclusion: These results confirm that disseminated MAC and M. simiae disease exist among AIDS patients in India also.