PCR in the Diagnosis of TB Meningitis

1Montefiore Medical Center, Bronx, NY

Meeting: Hospital Medicine 2008, April 3-5, San Diego, Calif.

Abstract number: 176

Case Presentation:

A 36‐year‐old man who had emigrated from Ecuador 4 years prior presented to the ED with 2 months of drenching night sweats and fever. Additional complaints included a productive cough with greenish sputum, an unintentional weight loss of 30 pounds, and generalized headache. Initial vitals signs were temperature 102.9°F, blood pressure 122/60 mm Hg, respiratory rate 30, heart rate 120, and SaO2 92% on room air. He appeared ill, lethargic, and diaphoretic. He had no photophobia, his neck was supple, and a lung exam was significant for bilateral coarse rhonchi. Initial WBC was 18,400 (79% polys, 13% bands). HIV test was negative. A CT of the chest revealed diffuse bilateral micronodular opacities with a cavitary lesion in the left upper lobe. His sputum smear was positive for AFB, and a 4‐drug regimen was initiated for pulmonary tuberculosis. MRI of the brain, performed to evaluate his persistent headaches, revealed multiple ring‐enhancing lesions involving the cerebrum, cerebellum, and basal ganglia. Lumbar puncture was significant for a WBC of 20,000 (66% polys, 33% lymphs), glucose of 47 (207 serum), and total protein of 66 and a AFB smear. TB meningitis was ultimately diagnosed after a spinal fluid sample sent for PCR was positive. At this point, steroids were added to his treatment plan. Interestingly, even after 6 weeks, the AFB culture remained negative.

Discussion:

CNS tuberculosis accounts for about 1% of all cases of TB and 6% of all extrapulmonary sources in immunocompetent individuals. Meningitis is by far the most common CNS manifestation, but space‐occupying lesions (tuberculomas) can also be present. These lesions can be multiple in number and can appear to be ring‐enhancing on neuroradiological imaging. CSF analysis classically results in moderately elevated protein and low glucose concentrations. Cell counts range between 0 and 1500/mm3 (predominantly lymphocytes). Up to 25% of patients have a majority of neutrophils, as was the case with our patient. AFB smears are often nondiagnostic, with a sensitivity of 20%. AFB cultures are better (50%‐80% sensitive) but are of limited clinical utility, as they require up to 6 weeks to establish a diagnosis. The use of MTB PCR on spinal fluid samples is becoming increasingly useful because the sensitivity/specificity (60% and 98%, respectively) is on par with a culture, and the results are back in hours instead of in weeks.

Conclusions:

This case illustrates the utility of using PCR to diagnose TB meningitis in the setting of a negative AFB smear.

Author Disclosure:

M. Shaines, none.

To cite this abstract:

Shaines M. PCR in the Diagnosis of TB Meningitis. Abstract published at Hospital Medicine 2008, April 3-5, San Diego, Calif. Abstract 176. Journal of Hospital Medicine. 2008; 3 (suppl 1). https://www.shmabstracts.com/abstract/pcr-in-the-diagnosis-of-tb-meningitis/. Accessed July 22, 2019.

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