SUPRANATIONAL REFERENCE LABORATORY NETWORK DST QA Round 11

SUPRA-NATIONAL REFERENCE LABORATORY NETWORK DST QA Round 11, 2004 A. Van Deun & F. Portaels

CONDUCT OF ROUND 11 • 20 strains, 10 in duplicate: total 30 cultures – non-MDR series: R-mono – 7 strains from Borstel, 6 from Paris SRL • pre-testing 7 Antwerp strains – MIC, sequencing – exclusion doubtful strains • mass culture from single colony • 0 contamination, 9 growth failures (#3, #9)

LABS AND METHODS, Rd 6 TO 11

JUDICIAL RESULTS OF ROUND 11 • INH – strains: 10 resistant, 10 susc. – cultures: 15 resistant, 15 susc. – agreement: 100% 18 strains 98% 2 strains

JUDICIAL RESULTS OF ROUND 11 • RIFAMPICIN – 10 resistant, 10 susceptible strains – 16 resistant, 14 susceptible cultures – agreement: 100% 19 strains 57% (judicial susc. ) 1 strain (#6)

JUDICIAL RESULTS OF ROUND 11 • STREPTOMYCIN – 11 resistant, 9 susceptible strains – 16 resistant, 14 susceptible cultures – agreement: 100% 13 strains 96% 2 strains 91% 1 strain 70% 2 strains (#1, 7) <70% 2 strains (#6, 9)

JUDICIAL RESULTS OF ROUND 11 • ETHAMBUTOL – strains: 5 resistant, 15 susc. – cultures: 7 resistant, 23 susc. – agreement: 100% 90 -99% 87% 70 -80% 9 strains 7 strains 1 strain 3 strains (#8, 11, 12)

RESULTS OF ROUND 11

RESULTS OF ROUND 11

RIFAMPICIN INTERMEDIATE RESISTANT STRAIN: results by method

COMPARISON PHENO / GENOTYPIC (SEQUENCING) • Results known for 7 Antwerp strains only • Perfect correlation for H and E • Poor correlation for S (rps. L, rrs 530, rrs 912) – 0/3 resistant have mutation • Perfect correlation for R with exception of the discordant strain – leu 533 pro mutation – majority finds susceptible

RIFAMPICIN PROBLEM STRAIN MICs

RIFAMPICIN PROBLEM STRAIN: CLINICALLY • #6, judicial HS resistant, 57% R-susceptible – patient from Bujumbura, Burundi – failure of 2 EHRZ / 4 H 3 R 3 – failure of 2 SEHRZ / 1 EHRZ / 5 E 3 H 3 R 3