Saurab Kishore Munshi

Molecular Approaches for Detection of the Multi-Drug Resistant Tuberculosis (MDR-TB) in Bangladesh

The principal obstacles in the treatment of tuberculosis (TB) are delayed and inaccurate diagnosis which often leads to the onset of the drug resistant TB cases. To avail the appropriate treatment of the patients and to hinder the transmission of drug-resistant TB, accurate and rapid detection of resistant isolates is critical. Present study was designed to demonstrate the efficacy of molecular techniques inclusive of line probe assay (LPA) and GeneXpert MTB/RIF methods for the detection of multi-drug resistant (MDR) TB. Sputum samples from 300 different categories of treated and new TB cases were tested for the detection of possible mutation in the resistance specific genes (rpoB, inhA and katG) through Genotype MTBDRplus assay or LPA and GeneXpert MTB/RIF tests. Culture based conventional drug susceptibility test (DST) was also carried out to measure the efficacy of the molecular methods employed. Among 300 samples, 191 (63.7%) and 193 (64.3%) cases were found to be resistant against rifampicin in LPA and GeneXpert methods, respectively; while 189 (63%) cases of rifampicin resistance were detected by conventional DST methods. On the other hand, 196 (65.3%) and 191 (63.7%) isolates showed isoniazid resistance as detected by LPA and conventional drug susceptibility test (DST), respectively. Among the drug resistant isolates (collectively 198 in LPA and 193 in conventional DST), 189 (95.6%) and 187 (96.9%) were considered to be MDR as examined by LPA and conventional DST, respectively. Category-II and -IV patients encountered higher frequency of drug resistance compared to those from category-I and new cases. Considering the higher sensitivity, specificity and accuracy along with the required time to results significantly shorter, our study supports the adoption of LPA and GeneXpert assay as efficient tools in detecting drug resistant TB in Bangladesh.

Evaluation of the effectiveness of BACTEC MGIT 960 for the detection of mycobacteria in Bangladesh

OBJECTIVE Tuberculosis (TB) caused by Mycobacterium tuberculosis has been identified as a re-emerging infectious disease with public health importance globally. Exploitation of new laboratory techniques for precise identification of mycobacteria in clinical specimens is of great importance to improve the diagnosis as part of the global TB control efforts. METHODS The current study was conducted for the evaluation of BACTEC MGIT 960 method in comparison with Lowenstein-Jensen (LJ) culture and light emitting diode (LED) fluorescence microscopy for isolation of mycobacteria among TB suspects from Bangladesh. A total of 421 specimens were tested with these methods. RESULTS Among the tested samples, 3.6% (n=15) were LED fluorescence microscopy positive; while 18 (4.2%) and 45 (10.6%) were recovered from LJ and MGIT 960 culture. The relative positivity found through MGIT 960 system were 60% and 66.7% higher than that of LJ culture and LED fluorescence microscopy, respectively. Recovery rate of Mycobacterium tuberculosis complex ([MTC], 21 by MGIT and 16 by LJ culture) and non-tubercular mycobacteria ([NTM], 24 by MGIT and 2 by LJ culture) by MGIT 960 was 24% and 96% greater, respectively than LJ culture. Moreover, MGIT 960 was found to be highly sensitive (100%), specific (93.3%), accurate (93.6%) and a more rapid method in detecting mycobacteria when compared with LJ culture. CONCLUSION Extended recovery of NTM and MTC through MGIT 960 urged frequent application of this method to detect mycobacteria more effectively and rapidly.

Drug-resistant bacterial pathogens in milk and some milk products

Purpose – Current study was carried to detect the presence of pathogenic bacteria including the drug-resistant ones from milk and milk products. The paper aims to discuss these issues. Design/methodology/approach – Twenty-six raw milk samples from ten different areas, 28 pasteurized milk samples from 12 different companies and 26 yogurt samples from ten different sources in Dhaka city were microbiologically analyzed through cultural and biochemical identification of the isolates. Drug resistance trait was also determined by the Kirby-Bauer method on Muller-Hinton agar. Findings – Out of 80 samples studied, 74 were found to harbor pathogens within a range of 102-104 cfu/ml, including Escherichia coli, Salmonella spp., Staphylococcus aureus, and Vibrio spp. The study of antibiogram revealed that most of the isolates were resistant against most of the commonly used antibiotics. Research limitations/implications – Employment of only cultural/ biochemical tests excluding the molecular detection of virulence an...

Isolation of pathogenic microorganisms from burn patients admitted in Dhaka Medical College and Hospital and demonstration of their drug- resistance traits

Objective To isolate and quantify the microflora from the burn patients admitted in the Division of Plastic Surgery and Burns outdoor patients in Dhaka Medical College Hospital, Bangladesh.

Microbiological profiling and the demonstration of in vitro anti-bacterial traits of the major oral herbal medicines used in Dhaka Metropolis

Present study attempted to assess the level of microbiological contamination in oral herbal medicines, frequently used for medications, through conventional cultural and biochemical tests along with the antibiogram of the isolates. Moreover, the anti-bacterial potential of the herbal medicines was also aimed to be checked by the agar well diffusion method and minimum inhibitory concentration (MIC) assay. Out of 10 categories of liquid oral herbal medicine samples (n = 50) studied, all were found to be contaminated with bacteria (103-105 cfu/mL), specifically with Staphylococcus spp. in 8 samples; while 2 samples harbored Klebsiella spp. Fungal presence was observed only in one sample. Study of antibiogram revealed Klebsiella spp. to be strongly resistant against penicillin G and erythromycin, whereas S. aureus possessed 80% sensitivity. The in vitro anti-bacterial activity was observed in 7 samples. Of them, one sample was found to exhibit the activity against almost all the test bacteria and another was found effective against 5 out of 8 test bacteria. Five samples showed the activity within a minor range while 3 samples were devoid of such trait. Samples 2 and 4 were found to stall the bacterial growth below 10 mg/mL of concentration in MIC test. Overall, the prevalence of specific pathogens was not so significant in the samples studied as well as only one drug-resistant isolate was identified. Besides, the anti-bacterial trait of 5 samples indicated that most of herbal medicines might be considered effective for medication.

Comparisons among the diagnostic methods used for the detection of extra-pulmonary tuberculosis in Bangladesh

The present study was an attempt to establish a suitable method for the effective diagnosis of extra-pulmonary tuberculosis in Bangladesh. In this regard, detection of Mycobacterium tuberculosis from 390 different extra-pulmonary specimens was performed by Bright-Field microscopy, light-emitting diode fluorescence microscopy and Lowenstein-Jensen culture methods, followed by an extensive comparison among these methods. M. tuberculosis was detected in 53 cases through the conventional Lowenstein-Jensen culture method; 49 cases were detected under Bright-Field microscope, whereas the light-emitting diode fluorescence microscopy detected 64 cases. Out of 53 culture-positive isolates, 12 were found to be multi-drug resistant. Light-emitting diode fluorescence microscopy was found to be more sensitive and effective than both the Bright-Field microscopy and the Lowenstein-Jensen culture methods. Incidentally, light-emitting diode fluorescence microscopy appeared imperative to detecting the multi-drug resistant tuberculosis.

Validation of γ-irradiation in controlling microorganisms in fish

Purpose – With a previous throughput of sea fish contamination with microorganisms, the present study extended the array of such spoilage over four other fish samples including Pseudapocryptes elongates, Scomberomorus cavalla, Xenentodon cancila and Otolithoides pama, evaluated the reductive impact of irradiation, and further validated the irradiation methodology in controlling the microbial quality of the sea fish samples. The paper aims to discuss these issues. Design/methodology/approach – Twelve samples of each sea fish were collected from super shops in Dhaka city and a portion of each sample was subjected to γ-irradiation at a dose of 3 kilo gray (kGy). Then, both non-irradiated and irradiated samples were tested for the presence of pathogenic bacteria though culture on different specific media followed by biochemical identification. Drug resistance among the pathogens was also investigated. Findings – Most of the non-irradiated samples were observed to harbor huge bacteria and fungi (1.3×102-1.5×10...