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Pulmonary Tuberculosis in HIV-infected Patients Presenting with Normal Chest Radiograph and Negative Sputum Smear



Author(s)

Mounika Arrabelli, Raghuram Reddy Adidala, Chakrapani Chatla, Shireesha T, Suryaprakash Chakramahanty and Malathi Jojula

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DOI:10.17265/2328-7136/2016.03.003

Deaths due to Tuberculosis (TB) are high among the TB-HIV co-infected patients. Among PLHIV most of the instances the sputum smear is found to be negative for MTb. Chest X-rays also don’t yield much diagnostic value mainly due to the advanced immune suppressed condition. This study makes an attempt to find out the utility of alternate staining methods such as Light Emitting Diode (LED), Fluorescent Microscopy (FM) and solid culture in resource limited settings for effective diagnosis of TB among PLHIV. 2 sputum samples were collected from 102 successive presumptive TB cases whose smear microscopy and X-Ray were negative for MTb among PLHIVs visiting ICTC at MGM hospital, Warangal, Telangana State, India. All the 102 samples were repeated with ZN microscopy and X-ray. Additionally LED and FM microscopy procedures were conducted with the NALC-NAOH concentration method. All the samples were inoculated on LJ medium for solid culture and all the positive cultures were subjected for biochemical test to identify phenotypic appearance, nitrate reduction, niacin and PNB susceptibility test for all the first line anti TB drugs as per standard guidelines. Samples found positive on microscopy were cross checked with Line probe assay (LPA). All the 102 samples collected showed negative for MTb on ZN technique and negative for pulmonary TB on chest X-rays. 15 samples were positive for MTb both on LED and FM. LPA reconfirmed the MTb in all the 15 samples tested with 11 sensitive for both INH and Rifampicin, 3 INH mono resistant and 1 Rif mono resistance patterns. Of the 102 inoculations in LJ medium, 25 culture inoculations were positive for MTb growth and also were confirmed as MTb strains based on morphological, biochemical test and growth was seen after 4th week of inoculation. Of the 25 culture positives 20 were sensitive for INH and Rif, 4 INH mono resistant and 1 resistant to all first line anti TB drugs. In smear negative and chest X-ray negative presumptive TB cases especially in immune compromised groups such as PLHIV, it is found to be useful to subject the sputum samples to LED and FM methods and at least solid culture wherever available. These methods clearly demonstrated additional yield over conventional ZN staining which can be recommended especially in the settings where high throughput equipment such as Xpert MTB/RIFor liquid culture is not available. These proactive measures can help in early diagnosis of TB which in turn can reduce mortality due to TB among PLHIV and break the chain of transmission of TB. Recommendations: Technology such as LED or FM microscopy can be advised for effective diagnosis of TB among Presumptive TB cases in PLHIV in settings where Xpert MTB/RIF is not available.

Tuberculosis, drug sensitivity, direct AFBvs, concentrated smear microscopy, LED microscopy and FM, Line Probe Assay, culture, DST