whether the combined results obtained with the different primers were as discriminative as those obtained with the techniques described above, as has been found by others, including ourselves.
J. Esteban, N. Zamora and A. Ortiz
Department of Clinical Microbiology, Fundacio´n Jime´nez Dı´az-UTE, Avenida Reyes Cato´licos 2, 28040 Madrid, Spain E-mail: jesteban@fjd.es
R E P L Y F R O M D R S A M P A I O A N D D R L E A˜ O
We thank Dr Esteban and colleagues for their interesting comments. We had the opportunity to read their article [4], and although it also evaluated other rapidly growing mycobacteria, our response here will be limited to Mycobacte-rium fortuitum. In brief, they investigated 16 M. fortuitum isolates using four different primers and a single method, RAPD, modified from the original protocol described by Zhang et al. [2]; however, ERIC-PCR or PFGE were not used. Consequently, we disagree with their claim that our results are not consistent with their own experience in this area, as this is limited to RAPD. We agree that RAPD analysis with different primer sets may improve clonality analysis, as described for Mycobacterium absces-sus by Zhang et al. [2], although RAPD has never been adequately validated for any of the rapid growing mycobacteria as recommended by the consensus guidelines of the ESCMID Study Group for Epidemiological Markers [7]. We also tested M. fortuitum outbreak isolates and unrelated control strains with primer OPA-2, but we did not follow the protocol of Zhang
et al. [2], as this has not been validated for
M. fortuitum. When a combined analysis was
performed with profiles obtained with RAPD1 and OPA2, control strain C6, epidemiologically unrelated to the outbreak, still clustered with the outbreak isolates. This is why we stated that PFGE and ERIC-PCR performed better than RAPD in terms of discriminating among the group of isolates and strains that we analysed [1].
J. L. M. Sampaio and S. C. Lea˜o
Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Sa˜o Paulo, Rua Botucatu, 862 3°andar. 04023–062, Sa˜o Paulo, SP, Brazil. E-mail: sylvia@ecb.epm.br
R E F E R E N C E S
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2. Zhang Y, Rajagopalan M, Brown BA, Wallace RJ. Randomly amplified polymorphic DNA PCR for comparison of Mycobacterium abscessusstrains from nosocomial outbreaks. J Clin Microbiol1997;35: 3132–3139.
3. Power EGM. RAPD typing in microbiology: a technical review.J Hosp Infect1996;34: 247–265.
4. Esteban J, Ferna´ndez Roblas R, Garcı´a Cı´a JI, Zamora N, Ortiz A. Clinical significance and epidemiology of non-pig-mented rapidly growing mycobacteria in a university hospital.J Infect2006; in press.
5. Lai KK, Brown BA, Westerling JA, Fontecchio SA, Zhang Y, Wallace RJ. Long-term laboratory contamination by Myco-bacterium abscessus resulting in two pseudo-outbreaks: recognition with use of random amplified polymorphic DNA (RAPD) polymerase chain reaction. Clin Infect Dis 1998;27: 169–175.
6. Matsiota-Bernard P, Zinzendorf N, Onody C, Guenounou M. Comparison of sensitive and clarithromycin-resistantMycobacterium aviumstrains isolated from AIDS patients during therapy regimens including clarithromycin.J Infect2000;40: 49–54.
7. Struelens MJ. Consensus guidelines for appropriate use and evaluation of microbial epidemiologic typing systems.Clin Microbiol Infect1996;2: 2–11.
