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 10% 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 95) were used during the laboratory work. Phenol 5% and ethanol alcohol 70% were used to sterilize and disinfect the benches and hood (IUATLD, 1996). Autoclave was used at 121 °C at 1.5 bar for 20-30 minutes for sterilizing all culture media. The study was conducted at National Reference Lab (NRL) of tuberculosis/Baghdad from July 2016 to December 2016. A total of 188 sputum samples were collected from suspected patient. In addition, 80 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 2-3 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 (3 to 5 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 –20 °C until use.
Results: Totally, 118 Tuberculosis suspected samples were used throughout this study; 103 (54.78%) cases were positive using direct assay (AFB smear microscopy) and 85 (45.21%) were negative cases. From the 103 TB patients, 88 (85.43%) represented as new TB cases; the others 15 (14.57%) patients appeared to follow up assessment of the directly observed treatment (DOT) program. The percentage of infected patients was 73 (70.87%) for males to 30 (29.12 %) for females, with over all male to female ratio of 2.43 (73/30) with a highly significant difference (P≤0.01). The age of the study patients ranged from 14 years to 75 years. The mean age was 36 and the median was 30 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 103 from 188 patients (suspected) were positive by using ZN smears (Ziehl-Neelsen stain technique). This study for those 188 suspected showed that 119 (63.29%) cases were positive by culture (Lowenstein–Jensen medium) and 69 (36.7%) cases were negative by L.J Culture. This study showed that the percentage of sensitivity, specificity, positive predictive value, and negative predictive value was 74.78%, 79.7%, 86.4% and 64.7%, respectively, using AFB method. The results revealed out of the total 188 specimens, 49 (26.06%) of the specimens were positive by DiaSpot (Tuberculosis Rapid Test on serum) and 139 (73.93%) specimens were negative. This study reported the sensitivity of 33.6% and the specificity of 86.95 % PPV 81.6 and NPV 43.16 for DiaSpot TB Rapid test.
Conclusion: Males aged 15 to 45 years are at high risk for TB infection. M. tuberculosis plays a major role for causing tuberculosis in human in Baghdad.