Two cases of iatrogenic levofloxacin-resistant pre-XDR tuberculosis in Japan

This case report discusses two instances of iatrogenically induced pre-extensively drug-resistant tuberculosis (pre-XDR TB). In both cases, the patients were initially diagnosed with tuberculosis and hospitalized in university hospitals. Nucleic acid amplification tests identified rifampicin-resistant tuberculosis, leading to a deviation from clinical guidelines. Without prior verification of susceptibility to other drugs, levofloxacin was added to the standard antituberculosis regimen, which included isoniazid, pyrazinamide, ethambutol, and rifampicin. Subsequent phenotypic drug susceptibility tests (DST) revealed resistance to isoniazid but susceptibility to levofloxacin, thus reclassifying the condition as multidrug-resistant tuberculosis (MDR-TB). However, by the time these patients were transferred to our hospital and began MDR-TB treatment, they had already developed resistance to levofloxacin, escalating their condition to pre-XDR TB. These cases underscore the importance of rapid access to comprehensive DST upon the identification of rifampicin resistance and adherence to established clinical guidelines.