Stem cells and its importance in respiratory medicine with special reference to tuberculosis.

Antibiotic susceptibility pattern of rapidlygrowing Mycobacteria R. Gayathri, K. Lily Therese, P. Deepa, S. Mangaiand H.N. Madhavan. J Postgrad Med 2010; 50: 76-8. The rapidly growing mycobacteria (RGM) causing human infections primarily consist of the Mycobacterium fortuitum group, Mycobacterium abscessus and Mycobacterium chelonae. The antibiotic susceptibility testing is important to determine the appropriate therapy as the antibiotics used to treat RGM are different from those used for treating infections caused by slow growers of mycobacteria. Aim was to determine antibiotic susceptibility of RGM using Kirby Bauer method and following Clinical and Laboratory Standards Institute (CLSI) guidelines. The retrospective styudy was conducted at Larsen and Toubro Microbiology Research Centre, Vision Research Foundation, Sankara Nethralaya, Chennai. The antibiotic susceptibility testing was performed following CLSI method for the drugs Amikacin, Azithromycin, Tobramycin, Ceftazidime, Cephotaxime, Cefuroxime, Cefaperazone, Ceftriaxone, Ciprofloxacin, Ofloxacin, Norfloxacin, Gatifloxacin and Moxifloxacin. Out of the 148 RGM isolates 146 (98%) were susceptible to amikacin, 138 (91%) to gatifloxacin, 132 (87%) to moxifloxacin, 122 (76%) to ciprofloxacin and 116 (74%) to Norfloxacin. Majority of the RGM were resistant to Ceftazidime, Cephotaxime and Cefaperazone. All the M. abscessus isolates were resistant to tobramycin. The in vitro antibiotic susceptibility testing by disc diffusion method showed that.majority of the RGM were sensitive to Amikacin followed by Gatifloxacin, Moxifloxacin and Ciprofloxacin.jefA (Rv2459), a drug efflux gene inMycobacterium tuberculosis confers resistance toisoniazid & ethambutol Anuj Kumar Gupta, Vineel P. Reddy, Mallika Lavania,D.S. Chauhan, K. Venkatesan, V.D. Sharma, A.K.Tyagi and V.M. Katoch. Indian J Med Res 2010;132: 176-88. Drug efflux pumps have been contributingfactor(s) in the development of multi drug resistancein various clinically relevant bacteria. During effluxpump gene expression studies on mycobacteria, wehave found a previously uncharacterized open readingframe (ORF) Rv2459 to be over expressed in drugstressed conditions. The objective of the presentstudy was to investigate the role of this ORF as adrug efflux pump, which might add new informationin our understanding about the alternativemechanisms of drug resistance in mycobacteria. Theopen reading frame Rv2459 of Mycobacteriumtuberculosis encoding a probable drug efflux proteinhas been cloned using pSD5 E.coli-Mycobacteriumshuttle vector and overexpressed in M. tuberculosisH37,Rv. This ORF was named as jefA. Overexpression of this gene in clones has been verifiedby real-time reverse transcription PCR. Minimuminhibitory concentrations (MICs) of recombinant aswell as non-recombinant clones were determined byresazurin microtitre assay plate method (REMA) withand without efflux pump inhibitors carbonyl cyanidem-chlorophenylhydrazone (CCCP) and verapamil. Inrecombinant strains of M. tuberculosis, the overexpression of this gene led to an increase in MIC ofanti-tubercular drugs isoniazid and ethambutol whentested by REMA. In the presence of CCCP andverapamil, the recombinant strains showed decreasein MIC for these drugs. Bioinformatic analysis hasshown a close relation of JefA protein with drugefflux pumps of other clinically relevant bacteria. In