′Pseudo′ Treatment Failure of Pulmonary Tuberculosis in Association with a Tuberculoma

Abstract

Failure of tuberculosis patients to respond to treatment is usually explained by one or more of five mechanisms: improper drug prescription; patient nonadherence to prescribed therapy; primary or acquired drug resistance; drug malabsorption; and rarely, exogenous reinfection with a drug-resistant isolate. Response to treatment is best measured bacteriologically; two different smear and one culture criteria for failure are widely used. Patients meeting either smear, but not culture, criteria for treatment failure may be said to have 'pseudo' treatment failure. Whether a patient can meet both smear criteria for failure, and not have a mechanism for treatment failure nor meet culture criteria, is unknown. A case of 'pseudo' treatment failure is reported in which both smear criteria for failure were met, but no mechanism for failure was proven to be operative. Key Words: Treatment failure; Tuberculosis; TuberculomaPseudo-échec du traitement de la tuberculose pulmonaire associée à un tuberculome RÉSUMÉ : L'échec du traitement de la tuberculose est en gé-néral causé par l'un des cinq phénomènes suivants : mauvais choix de médicament, non-observance au traitement de la part du patient, résistance primaire ou acquise au médica-ment, mauvaise absorption du médicament et, plus rarement, réinfection exogène par une souche résistante au médica-ment. La réponse au traitement se mesure le mieux par les analyses bactériologiques. On utilise le plus souvent deux frottis différents et une culture. Les patients qui répondent aux critères des frottis et non de la culture pour la définition de l'échec thérapeutique subiraient ce qu'on appelle un pseudo-échec du traitement. On ignore si un patient peut répondre aux critères associés au frottis pour l'échec thérapeutique et ne présenter aucun des phénomènes explicatifs ni répondre au critère associé à la culture. Un cas de pseudo-échec du traitement est décrit ici; il se caractérise par la présence des deux critères associés aux frottis, sans mécanisme explicatif.A ssuming that a curative regimen is available and can be tolerated, instances of tuberculosis (TB) treatment failure are almost always explained by one or more of five mechanisms: improper drug prescription; patient nonadherence to prescribed therapy; primary or acquired drug resistance; drug malabsorption; and rarely, exogenous reinfection with a drugresistant isolate (1-3). Depending upon their availability, sputum smear (World Health Organization [WHO]) or culture (American Thoracic Society [ATS]) criteria may be used to determine the presence of treatment failure. For the WHO, treatment failure is said to exist when a patient remains or again becomes smear-positive five months or more after starting treatment. It also is a patient who was initially smear-negative before starting treatment and becomes smear-positive after the second month of treatment (4). For the ATS, failure exists when the sputum culture fails to convert after five to six months of treatment (5). Culture criteria are the gold standard, but they have l...