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Letter
Rickettsioses in South Korea,
Materials and Methods
Pierre-Edouard Fournier,* Jean-Marc Rolain,* and Didier Raoult*
*Université de la Méditerranée, Marseille, France
Suggested
citation for this article
To the Editor: We read with interest the article by Choi et al.
(1), which describes the molecular detection of
Rickettsia typhi and 4 spotted fever group rickettsiae by nested
polymerase chain reaction (PCR) in the serum of febrile Korean patients.
The value of the study, however, is limited by imprecision, inconsistencies,
and the impossibility of verifying data. First, neither epidemiologic
nor clinical data are provided for studied patients, although these are
essential for interpreting PCR results. Second, multiplex nested PCR is
hampered by a high risk of contamination (2).
Alternatively, nested PCR techniques that use a closed assay or single-use
primers without positive controls limit such a risk (3).
In all cases, the use of negative controls is critical (2,3).
In this study, negative controls are neither described in the Materials
and Methods section nor shown on the gels. In addition, the authors used
as positive controls 4 of the 5 Rickettsia species they detected.
Therefore, apart from R. felis, which was not used as a positive
control, positive products may result from cross-contamination. Finally,
technically, the data are impossible to reproduce: 1) primer sets WJ77/80
and WJ79/83/78 cited in the legends of Figures
2 and 3
are neither described nor referenced in the text, 2) sequence of the RpCS.877p
primer in Table
1 differs from that in the referenced article (4),
3) described sequences have not been deposited in GenBank, and 4) all
rompB primers described in Table
1 exhibit 1–6 nucleotide mismatches with ompB sequences of
at least 1 of the detected species. Based on these errors, the 7 cases
of dual infections with R. conorii and R. typhi, which have
never been reported before, are doubtful, and these data need to be confirmed.
References
- Choi YJ, Jang WJ, Kim JH, Ryu JS, Lee SH, Park KH,
et al. Spotted
fever group and typhus group rickettsioses in humans, South Korea.
Emerg Infect Dis. 2005;11:237–44.
- Hayden RT. In vitro nucleic acid amplification techniques. In: Persing
DH, Tenover FC, Versalovic J, Tang YW, Unger ER, Relman DA, et al.,
editors. Molecular microbiology. Washington: ASM Press; 2003. p. 43–69.
- Fournier PE, Raoult D. Suicide
PCR on skin biopsy specimens for diagnosis of rickettsioses. J Clin
Microbiol. 2004;42:3428–34.
- Roux V, Rydkina E, Eremeeva M, Raoult D. Citrate
synthase gene comparison, a new tool for phylogenetic analysis, and
its application for the rickettsiae. Int J Syst Bacteriol. 1997;47:252–61.
Suggested citation
for this article:
Fournier P-E, Rolain
J-M, Raoult D. Rickettsioses in South Korea, materials and methods [letter].
Emerg Infect Dis [serial on the Internet]. 2006 Mar [date cited].
Available from http://www.cdc.gov/ncidod/EID/vol12no03/05-0334.htm
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