Pyrolysis mass spectrometry: a predictor of clinical response to treatment in pulmonary opportunist mycobacterial infection: preliminary work with M. malmoense.
Pyrolysis mass spectrometry (Py-MS) yields data reflecting overall cell composition. The changes in composition induced by treatment with rifampicin and ethambutol, alone and in combination, were investigated for a collection of seven strains of Mycobacterium malmoense from pulmonary infections. Two strains, both from patients that had responded to therapy with this combination, showed large changes in composition from control, untreated cultures. The difference was particularly marked for the ethambutol treated cultures. Four strains, all from patients who had failed to respond to therapy with this combination, showed minimal changes in composition for all treatments. The remaining strain also showed minimal treatment-induced change, but, for this patient, therapy with the combination had proved successful. Minimum inhibitory concentrations (MICs) were determined radiometrically. All strains showed MICs < 0.5 microgram/mL for rifampicin (sensitive) and of 8 micrograms/mL for ethambutol (resistant). MIC results did not correlate with clinical response, whereas the Py-MS results correlated with clinical response for six of the seven isolates. Py-MS may have a role in predicting effective therapy for this problem group.
Heginbothom
M L
ML
Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK.
Magee
J T
JT
D004977:Ethambutol / Q000627:therapeutic use; D006801:Humans; D008171:Lung Diseases / Q000188:drug therapy*; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D009164:Mycobacterium Infections / Q000188:drug therapy*; D009894:Opportunistic Infections / Q000188:drug therapy*; D012293:Rifampin / Q000627:therapeutic use
D004977:Ethambutol; D012293:Rifampin