In this work chitin was extracted chemically from shrimp shells. Seventeen Bacillus isolates were screened for chitinolytic activity. The chitinolytic strains of Bt. were screened at different temperatures and pHs for their hydrolytic potentials. By using a pair of specific primers, endochitinase gene was amplified from SBS Bt-5 strain through PCR, and then cloned into pTZ57 TA cloning vector and transferred in Escherichia coli DH5α strain. The sequenced gene (GenBank Accession No: HE995800) consists of 2031 nucleotides capable of encoding 676 residues. The protein consisted of three functional domains with a calculated molecular mass of 74.53 kDa and a pI value of 5.83. The amino acid sequence of chi gene showed 99% similarity to the genes of Bt MR11 endochitinase, Bt serovar kurstaki chitinase (kchi), Bt strain MR21 endochitinase and Bacillus cereus B4264.

Objective: To determine the susceptibility pattern and frequency of isolation of multidrug, pre-extensively drug and extensively drug resistant TB in a tertiary care hospital in Karachi, Pakistan. Method: A cross-sectional study was designed. Samples received in the lab were processed for growth and sensitivity testing of Mycobacterium tuberculosis. Isolation of MTB was done on Mycobacteria growth indicator tube (MGIT) followed by identification using MPT64. Samples were than evaluated for drug sensitivity against first and second-line antimycobacterial drugs. Statistical analysis was performed using SPSS version 24.0. Results: Of the 20014 samples received, 23.1% were identified as Mycobacterium tuberculosis. Drug sensitivity testing was performed on 95.9% isolates. Fifty-two percent samples were from males and 48% female patients. The study found statistically non-significant relationship between gender and likelihood of disease with drug-resistant (DR)-MTB organisms. The rate of isolation of MDR-TB was highest (43%) among ages 25-55 years and previously treated patients compared to newly diagnosed patients (62% vs 36%). Among MTB positive samples, 91.5% were pulmonary while 8.5% were extrapulmonary samples. Extrapulmonary samples were more likely to be sensitive to antimycobacterial drugs. The highest resistance was observed against Isoniazid (pulmonary=58%; extrapulmonary=12.7%), Rifampicin (pulmonary=58.7%; extrapulmonary=8.2%), and Levofloxacin (pulmonary=29.2%; extrapulmonary=20%). Conclusion: A considerable number of drug resistant tuberculosis cases were identified in the present study. It is essential to develop further strategies to reduce the spread of this disease. doi: https://doi.org/10.12669/pjms.38.ICON-2022.5778 How to cite this:Khursheed N, Asif S, Bano S, Ali MM, Adnan F. Susceptibility pattern of Mycobacterium tuberculosis over a period of five years at Indus Hospital and Health Network, Karachi, Pakistan. Pak J Med Sci. 2022;38(2):399-404.  doi: https://doi.org/10.12669/pjms.38.ICON-2022.5778 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Introduction: Typhoid remains a major healthcare problem in low and middle-income countries. The emergence of extremely drug-resistant (XDR) typhoid strains from the Indian subcontinent has led to very limited therapeutic options. Azithromycin being the only oral option for XDR typhoid faces a threat of rapid resistance due to its overuse after the COVID-19 pandemic.Objective: To evaluate the reliability of azithromycin disc diffusion testing against clinical isolates of typhoidal salmonellae in comparison with E-test minimum inhibitory concentrations (MICs).Study design: This is a cross-sectional validation study.

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Background: Assessment of the effectiveness of tuberculosis control strategies requires the periodic measurement of M. tuberculosis transmission in populations, which is notoriously difficult. One well-established method is to measure the prevalence of infectious pulmonary tuberculosis in the population which is then repeated at a second time point after a period of ‘intervention’, such as scale up of the Search-Treat-Prevent strategy of the Zero TB Cities initiative, allowing for a ‘before and after’ comparison.  Protocol: The concurrent adult pulmonary tuberculosis prevalence survey (using digital radiography and Xpert MTB/RIF Ultra) and child M. tuberculosis infection survey (using QuantiFERON-TB® Gold Plus) will primarily provide a baseline measure of the burden of adult infectious tuberculosis in Karachi and assess whether a large-scale interferon gamma release assay survey in children aged 2 to 4 years is feasible. The target population for the prevalence survey is comprised of a stratified random sample of all adults aged 15 years and above and all children aged 2 to 4 years resident in four districts in Karachi. The survey procedures and analyses to estimate pulmonary tuberculosis prevalence are based on the World Health Organization methodology for tuberculosis prevalence surveys. Ethics and dissemination: The study protocol has been approved by the Interactive Research Development / The Indus Hospital Research Centre Research Ethics Committee in Karachi, Pakistan and the London School of Hygiene & Tropical Medicine Research Ethics Committee. Due to non-representative sampling in this setting, where a large proportion of the population are illiterate and are reluctant to provide fingerprints due to concerns about personal security, verbal informed consent will be obtained from each eligible participant or guardian. Results will be submitted to international peer-reviewed journals, presented at international conferences and shared with participating communities and with the Provincial and National TB programme.