1640. Clinical Outcomes of Patients Based on Mycobacteria chelonae-abscessus Group Identification and Susceptibility Testing
Session: Poster Abstract Session: Mycobacterial Infections
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Background: Differences in antibiotic susceptibility for species within the M. chelonae-abscessus group are well-described. Correlation of species and antibiotic susceptibilities with patients’ clinical features and outcomes is less clear. We conducted a retrospective chart review to determine patient outcomes based on identification and susceptibility results.

Methods: Clinical isolates from 88 patients were previously speciated by high resolution melt analysis (HRM) of PCR products using hsp65 and secA1 as targets. Clarithromycin susceptibility by broth microdilution testing and erm(41) HRM PCR had been conducted for the M.abscessus complex isolates. Patient demographics, radiographic findings, treatment and outcomes were recorded.

Results: Patients’ isolates were identified by M.chelonae (27), M.abscessus (43), M.massiliense (15), and M.bolletii(3) (former nomenclature). Specimen sources included 58 pulmonary, 22 extrapulmonary, and 8 of undetermined origin. Of these, 41 were clinically significant and treated.

Among the 26 clinically significant pulmonary isolates, there were 12 M.abscessus, 7 M.massiliense, 6 M.chelonae, and 1 M.bolletii. Clinical data was available for 22. For these 22, epidemiologic and radiographic features did not differ based on the infecting species. The presence of the erm(41) deletion mutation did not correlate with clinical outcome (p=0.60). Patients with M.abscessus pulmonary infections were more likely to have clarithromycin resistance compared to those with non-abscessus infections (83.3% and 7.1%, respectively; p=0.001). Clarithromycin resistance was more common in patients with relapsed/persistent infection versus those with resolved infection (70.0% and 30.0% respectively; p=0.018). Although not statistically significant, patients infected with M.abscessus tended to have relapsing or persistent disease compared to those with non-abscessus species (58.3% and 20.0%, respectively; p=0.08).

Conclusion: Speciation of M.chelonae-abscessus appears useful as M.chelonae and M.massiliense pulmonary infections tend to have more favorable outcomes versus those with M.abscessus. Patients with clarithromycin susceptible isolates by broth microdilution also appear to have better clinical outcomes.

Kennon Miller, MD, Pathology and Laboratory Medicine, Cleveland Clinic, Cleveland, OH, Marion Tuohy, MT ASCP, Cleveland Clinic, Cleveland, OH, Susan M. Harrington, PhD, Microbiology, Cleveland Clinic, Cleveland, OH and Lulette Tricia Bravo, MD, Infectious Disease, Cleveland Clinic Foundation, Cleveland, OH

Disclosures:

K. Miller, None

M. Tuohy, None

S. M. Harrington, None

L. T. Bravo, None

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