A study of Mycobacterium tuberculosis Zopf, ۱۸۸۳ (Mycobacteriaceae) in Iraq

Background: Tuberculosis (TB) is considered to be one of the deadliest bacterial infections in the world and it can have a large impact on global health, drawing international attention with increasing number of cases worldwide in developed and developing countries. Mycobacterium tuberculosis (MTB) is the main causative agent of TB which is an aerobic pathogenic bacillus that establishes infection in the lungs. It is believed that two billion people are carrying non-eradicated intra-granulomatous Tuberculosis bacilli as LTBI (short for latent tuberculosis infection) and around ۱۰% of those people will be infected with active tuberculosis during their lifetime. Therefore, this study aimed to study Mycobacterium tuberculosis in Iraq.Methods: All bacteriological tests were done in biological safety cabinet class II. Gloves and masks (N ۹۵) were used during the laboratory work. Phenol ۵% and ethanol alcohol ۷۰% were used to sterilize and disinfect the benches and hood (IUATLD, ۱۹۹۶). Autoclave was used at ۱۲۱ °C at ۱.۵ bar for ۲۰-۳۰ minutes for sterilizing all culture media. The study was conducted at National Reference Lab (NRL) of tuberculosis/Baghdad from July ۲۰۱۶ to December ۲۰۱۶. A total of ۱۸۸ sputum samples were collected from suspected patient. In addition, ۸۰ samples were collected from healthy subjects Specimens were amassed within the outdoor and as away as feasible from different human beings. Each subject was advised to inhale deeply ۲-۳ instances, cough out deep from the chest and spit the sputum into sterile prevalent container. We needed to ensure that the specimen was of enough extent (۳ to ۵ mL) and that it incorporated strong or purulent material. Two samples were gathered from the subject. The first was taken when they reached the institute and the second was taken early morning, earlier than breakfast. The early morning collection represents the pulmonary secretions accrued in a single day, and consequently it typically has a better positivity. Gathered specimens were stored at –۲۰ °C until use.Results: Totally, ۱۱۸ Tuberculosis suspected samples were used throughout this study; ۱۰۳ (۵۴.۷۸%) cases were positive using direct assay (AFB smear microscopy) and ۸۵ (۴۵.۲۱%) were negative cases. From the ۱۰۳ TB patients, ۸۸ (۸۵.۴۳%) represented as new TB cases; the others ۱۵ (۱۴.۵۷%) patients appeared to follow up assessment of the directly observed treatment (DOT) program. The percentage of infected patients was ۷۳ (۷۰.۸۷%) for males to ۳۰ (۲۹.۱۲ %) for females, with over all male to female ratio of ۲.۴۳ (۷۳/۳۰) with a highly significant difference (P≤۰.۰۱). The age of the study patients ranged from ۱۴ years to ۷۵ years. The mean age was ۳۶ and the median was ۳۰ with highly significant difference between age group. As in many developing countries, direct sputum microscopy is the widely used method for the diagnosis of pulmonary TB in Iraq. Only ۱۰۳ from ۱۸۸ patients (suspected) were positive by using ZN smears (Ziehl-Neelsen stain technique). This study for those ۱۸۸ suspected showed that ۱۱۹ (۶۳.۲۹%) cases were positive by culture (Lowenstein–Jensen medium) and ۶۹ (۳۶.۷%) cases were negative by L.J Culture. This study showed that the percentage of sensitivity, specificity, positive predictive value, and negative predictive value was ۷۴.۷۸%, ۷۹.۷%, ۸۶.۴% and ۶۴.۷%, respectively, using AFB method. The results revealed out of the total ۱۸۸ specimens, ۴۹ (۲۶.۰۶%) of the specimens were positive by DiaSpot (Tuberculosis Rapid Test on serum) and ۱۳۹ (۷۳.۹۳%) specimens were negative. This study reported the sensitivity of ۳۳.۶% and the specificity of ۸۶.۹۵ % PPV ۸۱.۶ and NPV ۴۳.۱۶ for DiaSpot TB Rapid test.Conclusion: Males aged ۱۵ to ۴۵ years are at high risk for TB infection. M. tuberculosis plays a major role for causing tuberculosis in human in Baghdad.

Keywords:

tuberculosis , Mycobacterium tuberculosis , patients , Infection , Baghdad