Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 28, Num. 4, 2010, pp. 412-413

Indian Journal of Medical Microbiology, Vol. 28, No. 4, October-December, 2010, pp. 412-413

Correspondence

Cutting costs on mono-resistant tuberculosis diagnosis could eventually end up being more expensive

F Rouzaud¹, J Robledo²

¹ Corporación para Investigaciones Biológicas (CIB), Medellín, Colombia
² Corporación para Investigaciones Biológicas (CIB), Medellín; Escuela de Ciencias de la Salud, Universidad Pontificia Bolivariana, Medellín, Colombia
Correspondence Address: J Robledo, Corporación para Investigaciones Biológicas (CIB), Medellín; Escuela de Ciencias de la Salud, Universidad Pontificia Bolivariana, Medellín, Colombia
jrobledo@cib.org.co

Date of Submission: 26-Apr-2010
Date of Acceptance: 14-May-2010

Code Number: mb10124

PMID: 20966587
DOI: 10.4103/0255-0857.71808

Dear Editor,

Nalini and colleagues propose the combination of Isoniazid (H) and Rifampicin (R) in a single Lowenstein-Jensen medium for the detection of multidrug-resistant tuberculosis (MDR-TB) isolates. ^[1] While simplification of workload and reduction of costs associated with drug combinations are important parameters in resource-limited settings, we draw attention to the potential consequences of such a diagnostic method. In an H+R medium, one cannot distinguish bacilli that are H mono-resistant from those that are R mono-resistant. However, such a distinction is critical to determining an adequate regimen of treatment as recommended by the World Health Organization (WHO).^[2] The WHO indicates that patients mono-resistant to H should be treated with a combination of first-line drugs (namely, R, Pyrazinamide [Z] and Ethambutol [E]) for 6 to 9 months whilst R mono-resistance implies a treatment with H, E and fluoroquinolones for up to 18 months, in addition to at least 2 months of Z. Cost differences involved in such treatments cannot be overlooked, especially in developing countries, and the side effects associated with the use of fluoroquinolones should not be neglected. ^[3] This underscores the necessity to distinguish isolates that are R or H mono-resistant. Although generally low, ^[4],[5] R mono-resistance must be taken into consideration in the design of a treatment regimen. Nalini and colleagues mention that an R medium could be included together with the H+R one in order to detect R mono-resistance. However, in that situation, the benefits associated with workload and cost reduction would become irrelevant. In conclusion, we stand by the current WHO recommendations of using separate H and R media and caution diagnostic laboratories against the use of a combined H+R medium, as such a simplification would hide mono-resistant isolates, leading to an inadequate treatment regimen with the consequences mentioned above.

References

1.	Nalini S, Lakshmi R, Devika K, Ravikumar D, Ramachandran R. Combined drug medium with isoniazid and rifampicin for identification of multi-drug resistant Mycobacterium tuberculosis. Indian J Med Microbiol 2010;28:162-3.  Back to cited text no. 1  [PUBMED]
2.	World Health Organization (WHO) (Guidelines for the programmatic management of drug-resistant tuberculosis. ͻWHO/HTM/TB/2008.402΋. Emergency Update 2008.  Back to cited text no. 2
3.	Lode H. Safety and tolerability of commonly prescribed oral antibiotics for the treatment of respiratory tract infections. Am J Med 2010;123:S26-38.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]
4.	Matos ED, Lemos AC, Bittencourt C, Mesquita CL. Anti-tuberculosis drug resistance in strains of Mycobacterium tuberculosis isolated from patients in a tertiary hospital in Bahia. Braz J Infect Dis 2007;11:331-8.  Back to cited text no. 4
5.	Joseph MR, Shoby CT, Amma GR, Chauhan LS, Paramasivan CN. Surveillance of anti-tuberculosis drug resistance in Ernakulam District, Kerala State, South India. Int J Tuberc Lung Dis 2007;11:443-9.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]

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