Sethumadhavan Muralidharan

Role of risk factors and socio-economic status in pulmonary tuberculosis: a search for the root cause in patients in a tertiary care hospital, South India.

Objective  To determine the frequency of underlying risk factors and the socio‐economic impact based on occupation in the development of tuberculosis.

Blastomycosis in a South Indian patient after visiting an endemic area in USA.

We describe a case of blastomycosis in a diabetic patient from South India who had visited Milwaukee, Wisconsin, an endemic area for blastomycosis in the USA. After his return to Bangalore, India, the patient developed intermittent fever of moderate to high grade, cough, loss of weight and appetite, and abscesses in the left cubital fossa and thigh regions. Systemic examination at our hospital revealed that he had dullness to percussion over the chest region and decreased breath sounds. Direct examination of Gram-stained smears of the pus from an abscess showed many broad-based budding yeast cells and culture yielded a dimorphic fungus later identified as Blastomyces dermatitidis. Histologic examination of the curettage tissue slides stained with hematoxylin and eosin, periodic acid Schiffs reagent, and Gomoris methenamine silver stain procedures showed many broad-based budding cells characteristic of B. dermatitidis. The patient was successfully treated, initially with amphotericin B, followed by oral itraconazole for a period of 6 months. Blastomycosis cases in India are reviewed and the likely source of infection in this patient is discussed.

Ceftriaxone resistant Shigella Flexneri, an emerging problem

Shigellosis is a disease of public health importance in developing countries. It may cause self-limited diarrhea to severe dysentery. Emergence of multi drug resistant (MDR) strains is a growing concern globally. Ceftriaxone and ciprofloxacin are the drugs of choice for MDR cases. Here, we report a case of MDR Shigella flexneri from an immunocompromised patient. The strain was resistant to ceftriaxone [minimum inhibitory concentration (MIC) ≥ 64 μg/ml], limiting the treatment option. Simultaneously, the strain was also found to be resistant to ciprofloxacin (MIC ≥ 4 μg/ml). However, it was susceptible to ceftazidime (MIC 4 μg/ml). This is the first case of ceftriaxone resistant Shigella spp. reported from our hospital.

In Vitro Evaluation of the Antimicrobial Efficacy of Four Endodontic Biomaterials against Enterococcus faecalis, Candida albicans, and Staphylococcus aureus

Root canal sealers that possess good antimicrobial property can prevent residual and recurrent infection and contribute to successful endodontic therapy. This study evaluated the antimicrobial activity of four endodontic sealers, AH Plus, Tubliseal EWT, EndoRez, and iRoot SP, against three different microorganisms, E. faecalis, C. albicans, and S. aureus, by direct contact test. 10 μL microbial suspensions were allowed to directly contact the four endodontic sealers for 1 hr at 37°C. Subsequently microbial growth was measured spectrophotometrically every 30 min for 18 hours. The microbial suspensions were simultaneously tested to determine the antimicrobial effect of components which are capable of diffusing into the medium. The results revealed that AH Plus and iRootSP had significantly higher antimicrobial activity against E. faecalis. AH Plus and Tubliseal EWT showed significantly higher antimicrobial activity against C. albicans and S. aureus compared to iRoot SP and EndoRez. EndoRez showed the least antimicrobial activity against all the three microorganisms. Inhibition of microbial growth is related to the direct contact of microorganisms with the sealers. In conclusion AH Plus had significantly higher antimicrobial activity against E. faecalis, C. albicans, and S. aureus.

Multi-drug-resistant tuberculosis: the experience of an urban tertiary care hospital in South India using automated BACTEC 460 TB.

The emergence of multi-drug-resistant (MDR) strains has been a major obstacle in the tuberculosis (TB) control programme. In the present study we looked into the prevalence of MDR-TB in an urban tertiary care hospital in South India over four years (2007–2010). During this period, 641 clinical specimens (317 respiratory specimens and 324 non-respiratory specimens) were received for mycobacteriological culture and drug susceptibility testing for first-line drugs, using the BACTEC 460 TB system. Mycobacterium tuberculosis (MTB) was isolated in 34.8% (n = 223) specimens. Of the total 223 MTB isolates 83 (37.2%) were MDR. Forty-two percent of the pulmonary MTB isolates (n = 72) and 20.4% of the extra-pulmonary isolates (n = 10) were MDR. Although we observed a high percentage of drug resistance, the prevalence of MDR was not observed to vary significantly within the four years which suggested good management.

Epidemiology of culture isolates from peritoneal dialysis peritonitis patients in southern India using an automated blood culture system to culture peritoneal dialysate.

Aim:  Continuous ambulatory peritoneal dialysis (CAPD) is a major form of therapy for chronic end stage renal disease patients, which may lead to CAPD‐associated peritonitis. The spectrum of organisms associated with CAPD peritonitis varies geographically. Not much data is available regarding this from southern India. The aim of this study was to characterize the spectrum of organisms associated with CAPD peritonitis in this region and observe the utility of automated blood culture systems to culture peritoneal dialysate.

Direct drug susceptibility testing of Mycobacterium tuberculosis to primary anti-tubercular drugs by nitrate reductase assay.

OBJECTIVES Traditional drug susceptibility testing for Mycobacterium tuberculosis takes weeks and/or expensive. In this study, we evaluated nitrate reductase assay for drug susceptibility testing which is faster than the visual detection of colonies. MATERIALS AND METHODS 32 clinical specimens (direct microscopy positive for AFB with 1+, 2+ or 3+ grading) were decontaminated and the sediment was inoculated onto the L-J medium with INH or Rifampicin incorporated with Potassium nitrate and the same medium without antibiotics at 1;10 dilution as control. After 2 weeks, the control was first tested for color change with addition of nitrate reductase reagents. If found positive, the media with antibiotics were tested and compared. Futher incubation was done if the control was found to be negative. The results obtained was compared with standard direct proportion method for drug susceptibility testing. RESULTS Resistance of isolates as shown by both methods for INH and Rifampicin was 37.5% and 31.3% respectively. The results showed that NRA and proportion method do not differ significantly ( P < 0.05 for both drugs). Thus an excellent agreement between the results of NRA and proportion method was found for two primary anti-tubercular drugs, 87.5% for INH and 97% for Rifampicin. CONCLUSION Nitrate reductase assay is a rapid and inexpensive method for susceptibility testing of M. tuberculosis for primary anti-tubercular drugs and could be an alternative to existing methods, particularly in resource poor settings.

Comparison among three cold staining methods in the primary diagnosis of tuberculosis: a pilot study

OBJECTIVE In developing countries, sputum smear microscopy is the main tool for pulmonary tuberculosis case finding. The objective of the present study was to evaluate the diagnostic efficacy of Gabbetts staining (GS) and modified cold staining (MCS), both of which are two-step methods, in comparison with that of fluorescent staining (FS), which is a three-step method, for the detection of AFB in sputum smears. METHODS Our sample comprised 260 sputum samples collected from individuals suspected of having pulmonary tuberculosis at Kasturba Hospital, in Manipal, India. Smears were prepared in triplicate: one each for FS, MCS, and GS. The smears were randomly numbered so that the examiner was blinded to the sample identities. RESULTS Of the 260 samples, 16 (6.15%), 15 (5.77%), and 13 (5.00%) showed positive AFB results with FS, MCS, and GS, respectively. The sensitivity of GS and MCS, in comparison with that of FS, was 81.25% and 93.75%, respectively. The concordance of GS and MCS with FS was good (0.988 and 0.996, respectively), and no statistically significant differences were found. CONCLUSIONS Although MCS and GS were found to be less sensitive than was FS, which is evaluated under fluorescence microscopy, the first two are promising methods for the diagnosis of tuberculosis.

In vitro production of biofilm in a flow cell system in a strain of Pseudomonas aeruginosa and Staphylococcus aureus and determination of efficiency of ciprofloxacin against them

BACKGROUND Microorganisms develop biofilm on various medical devices. The process is particularly relevant in public health since biofilm associated organisms are much more resistant to antibiotics and have a potential to cause infections in patients with indwelling medical devices. MATERIALS AND METHODS To determine the efficiency of an antibiotic against the biofilm it is inappropriate to use traditional technique of determining Minimum Inhibitory Concentration (MIC) on the free floating laboratory phenotype. Thus we have induced formation of biofilm in two strains (Pseudomonas aeruginosa and Staphylococcus aureus, which showed heavy growth of biofilm in screening by Tube method) in a flow cell system and determined their antibiotic susceptibility against ciprofloxacin by agar dilution method in the range (0.25 mg/ml to 8 mg/ml). The MIC value of ciprofloxacin for the biofilm produced organism was compared with its free form and a standard strain as control on the same plates. OBSERVATIONS Both the biofilm produced strains showed a higher resistance (MIC > 8 mg/ml) than its free form, which were 2 μg/ml for Pseudomonas aeruginosa and 4 mg/ml for Staphylococcus aureus. Thus biofilm can pose a threat in the patient treatment.

Diagnostic efficacy of Ziehl-Neelsen method against fluorescent microscopy in detection of acid fast bacilli

Objective To investigate the application of Ziehl-Neelsen (Z-N) and fluorescent microscopy in detection of acid fast bacilli (AFB). Methods Duplicate smears were prepared from 260 sputum samples and stained with Z-N and fluorescent staining (FS) methods. The efficiency of both methods in primary diagnosis of tuberculosis were evaluated. Results The smears were positive for AFB in 15 (5.77%) samples by Z-N staining method and in 16 (6.15%) samples by FS method. The sensitivity and specificity of Z-N staining method against FS method were 93.75% and 100% respectively. Conclusions Though lesser cost-effective than Z-N, FS method is a more sensitive and better case finding tool in detection of AFB.