In vitro activity of daptomycin & linezolid against methicillin resistant Staphylococcus aureus & vancomycin resistant enterococci isolated from hospitalized cases in Central India.

Background & objectives: Growing incidence of methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enteroccoci (VRE) is posing a therapeutic problem due to limited drug options. Therefore, the present study was undertaken to check susceptibility of MRSA and VRE isolates against new antimicrobials such as daptomycin and linezolid. Methods: A total of 586 Gram-positive isolates comprising 442 S. aureus and 144 enterococci isolated from hospitalized cases included in the study, were subjected to in vitro antimicrobial susceptibility testing by disc diffusion method. One hundred twenty four enterococci obtained from rectal swabs of neonates were also included. Minimum inhibitory concentration (MIC) was determined for daptomycin, linezolid, vancomycin and teicoplanin against 50 each isolates of MRSA and VRE by E strip. Results: Among the staphylococci, 326 (73.85%) isolates were MRSA. MIC for vancomycin and teicoplanin among MRSA was ≤3 μg/ml. MIC for daptomycin among MRSA was found to be in the range of 0.064-1.5 μg/ml. Percentage of VRE among clinical samples was 14.29 per cent while it was 47.06 per cent among enterococci from rectal swabs of neonates. MIC was >256 μg/ml for vancomycin among VRE and was associated with van A genotype. MIC range for daptomycin among VRE was 0.38-3 μg/ml. MIC for linezolid among MRSA and VRE was in the range of 0.25 to 1 and 0.38 -1.5 μg/ml, respectively. Interpretation & conclusions: The present study showed a rise in MIC to vancomycin for sizable number of MRSA and growing percentage of VRE at our centre. Daptomycin and linezolid showed 100 per cent activity against MRSA and VRE.

In-house, simple & economical phage technique for rapid detection of rifampicin, isoniazid, ethambutol, streptomycin & ciprofloxacin drug resistance using Mycobacterium tuberculosis isolates.

Background & objectives: Multiple drug resistance (MDR) among Mycobacterium tuberculosis poses a serious therapeutic problem. Early detection of MDR can be valuable but the conventional drug susceptibility tests take 4-6 wk time after the laboratory isolation of M. tuberculosis. The bacterial phage assay has been reported as a rapid tool for rifampicin susceptibility testing of tubercle bacilli using the suspension of isolated cultures. The present study was aimed to set up a phage assay for testing drug susceptibility to isoniazid (INH), rifampicin, ethambutol, streptomycin and ciprofloxacin in M. tuberculosis isolates. Methods: Mueller-Hinton broth instead of Middle Brook 7H9 broth was used to make it more economical. The phage assay was compared with the proportion method using 100 M. tuberculosis isolates from pulmonery TB cases. Phage assay results were available in 48 h for rifampicin and streptomycin while 72 h required for INH, ethambutol and ciprofloxacin. The assay was compared with gold standard proportion method. Interpretation of the results was easy and clear. Results: In the present study, sensitivity and specificity of the phage assay when compared to proportion method were in the range of 97 to 100 per cent for all the drugs except for ciprofloxacin for which it was 93 and 96 per cent, respectively. Interpretation & conclusions: The phage assay was economic, easy to perform and rapid for the detection of drug resistance in M. tuberculosis isolates with no requirement of expensive equipment. It is within the reach of microbiology laboratories in developing countries having high loads of tuberculosis.

Chronic knee monoarthritis caused by Mycobacterium chelonae.

Extrapulmonary tuberculosis occurs in 20% of all patients with tuberculosis and tubercular arthritis occurs in 10% of those with extrapulmonary tuberculosis. Arthritis caused by Mycobacterium tuberculosis is not uncommon in India. However, arthritis caused by Mycobacterium chelonae has not been reported to the best of our knowledge. We report a patient with arthritis caused by Mycobacterium chelonae in whom the diagnosis was confirmed by smear and culture of acid-fast bacilli. Polymerase chain reaction of the synovial fluid using IS6110 was negative.

Role of cancer antigen-125 from pleural & ascitic fluid samples in non malignant conditions.

BACKGROUND & OBJECTIVE: CA-125, an ovarian tumor marker is known to increase in non malignant conditions such as tubercular and non tubercular pleuritis and ascites. We undertook this study to evaluate non-specific rise in CA-125 levels in conditions associated with pleural effusion and ascites and also to understand the mechanism of its secretion. METHODS: CA-125 levels in 38 pleural and 46 ascitic fluid samples from non malignant cases and 10 blood samples from pulmonary tuberculosis cases were estimated by ELISA. The ascitic fluid samples were collected from cases of bacterial peritonitis, tuberculosis, hepatitis, cirrhosis of other aetiology and pleural fluid samples were from cases of tubercular, pyogenic, cardiomegaly and other conditions. RESULTS: Both ascitic and pleural fluid samples (transudative and exudative) showed elevated CA- 125 levels. The CA-125 levels were significantly higher in ascitic fluid samples than in pleural fluid samples. INTERPRETATION & CONCLUSION: Our findings showed that elevated levels of CA-125 in pleural and ascitic fluid could be because of varied aetiologies which need to be ruled out before considering malignancy. Peritoneum has a greater capacity to secrete CA-125 than the pleural epithelium and the secretion occurs following inflammation or mechanical distress. Pulmonary tuberculosis as a closed lesion without involvement of pleural epithelium does not evoke high CA-125 release.

Modified blood supplemented Lowenstein Jensen medium improves recovery of mycobacteria from sputum samples.

Lowenstein Jensen medium containing 3% human blood in CPDA anticoagulant was compared with plain LJ medium for mycobacterial growth using 565 sputum samples. Mycobacterial growth appeared on both the media in case of 148 samples. However, growth was faster by one week and colony size larger over blood supplemented LJ in 53 of the 145 culture positives. Additional 12 samples which showed no growth on plain LJ could grow only on LJ supplemented with blood. While 3 samples revealed scanty growth on plain LJ alone. The experience suggests that two LJ slants; one plain and the other supplemented with blood be in inoculated routinely to increase speed of growth and recovery of mycobacteria from clinical samples.