In a recent case report published in the North American Journal of Medical Sciences, a team of researchers found that Mycobacterium tuberculosis (MTB) is an infrequent finding, but considered a potential pathogen in patients with Cystic Fibrosis, and may lead to serious pulmonary complications if there is a delay in diagnosis and treatment.
Cystic Fibrosis (CF) is a life-threatening autosomal recessive genetic disorder that primarily affects the lungs and digestive system. Risk factors such as chronic pulmonary disease, diabetes mellitus, malnutrition, steroid treatment, ethnic origin, and geographic location predispose CF patients to MTB infection.
In the case report titled “Pulmonary Tuberculosis in a Patient with Cystic Fibrosis,” Naveen Patil from the University of Arkansas for Medical Sciences, and colleagues, reported the case of a female aged 24 years with a diagnosis of Cystic Fibrosis after being admitted to the hospital with a 2-week history of coughing, severe right-side chest pain, worsening cough, fevers and a weight loss of 10 pounds.
Past sputum cultures had grown methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa and past acid-fast bacilli (AFB) cultures revealed no growth.
Results revealed that the forced expiratory volume (FEV1) and forced vital capacity (FVC) in patients had dropped to 57 and 42% in comparison to baseline results of 103 and 79%, respectively. Results from computed tomography (CT) and chest radiograph showed multiple bilateral cavitary lesions that had worsened and the chronic collapse of the anterior subsegment of the right upper lobe of the lung.
Clinicians decided to start treatment with broad-spectrum antibiotics including levofloxacin, amikacin, and vancomycin, however, there were no clinical improvements after a treatment of 4 weeks. Results from subsequent cultures showed the growth of MTB after 4 weeks, sensitive to all first-line TB drugs.
Based on the culture results, the clinicians decided to put the patient under a four drug anti-tuberculous regimen of rifampin (RIF), isoniazid (INH), pyrazinamide (PZA) and ethambutol (EMB). The patients continued under this regimen for a period of 2 months. This was followed by a treatment with INH and RIF for 4 months.
Following this treatment, the patient had full resolution of her febrile episodes and her submissive hemoptysis. She also increased her weight.
Results from AFB cultures following 2 and 6 months of treatment were all negative for MTB and a radiograph of the chest 7 months after the initial diagnosis revealed clearing of the multiple bilateral cavitary lesions. There were also improvements in FVC to 85% and FEV1 to 58%.
Based on this case report, the researchers concluded that MTB is a rare but potential pathogen in CF. The diagnosis should be considered in CF patients with nonresolving and progressive respiratory symptoms despite adequate therapy for other common infections like Pseudomonas and NTM. Treatment of MTB infection in CF patients follows the standard therapeutic regimen of TB, but may require modification in the duration and choice of anti-TB agents depending on the patient’s response to therapy.