Use of the Polymerase Chain Reaction for the Detection

Clinical Infectious Diseases 1997;25:939 SIR—We read with interest the article by Murdoch et al. [1], q 1997 by The University of Chicago. All rights reserved. 1058–4838/97/2504–0035$03.00 which described the use of PCR to detect Legionella DNA in urine and serum samples from patients with pneumonia. We have previously used the PCR method to detect Legionella DNA in respiratory samples [2]. In the present study a PCR technique with primers that specifically amplify a 700-bp segment of Legionella pneumophila [3] was used to detect the Problems with Antibiotic Resistance in Spain and Their DNA of this bacterium in serum samples from patients with Relation to Antibiotic Use in Humans Elsewhere pneumonia. We studied serum samples from 41 patients with proven legionellosis: nine patients had cultures positive for L. pneumophila, and 32 patients had serological evidence of SIR—We congratulate Baquero et al. [1] and the editors of Clinical L. pneumophila infection, as shown by indirect immunofluoInfectious Diseases for their willingness to publish this interesting rescence assay with use of L. pneumophila serogroup 1 as antistatement concerning problems with antibiotic resistance in Spain, gen. The sera of 10 patients with pneumonia due to other organpossible reasons for these problems, and suggestions for future isms were used as controls. action. The accompanying editorial by Levy [2] reflects some misTotal DNA from the serum samples was extracted with use conceptions regarding the relationship between the use of antibiotof a DNA extraction reagent containing Chelex anion-exchange ics and the development of antibiotic resistance; these misconcepresin (Perkin Elmer, Roissy, France). The PCR products were tions show that there has until now been a general lack of visualized after agarose gel electrophoresis and ethidium broinformation about antibiotic use in various settings, i.e., among mide staining were performed. L. pneumophila DNA was deand within countries, in general practice and in hospitals, and in tected in 12 serum samples (30%) from the 41 patients with veterinary settings. legionellosis, and it was not detected in serum samples from Scandinavian investigators have in recent years published data the 10 controls. We did not find that the presence of L. pneuon the general consumption of antibiotics by humans, as measured mophila DNA in the serum samples correlated with positivity in defined daily doses (DDD) per 1,000 inhabitants per day (figure of bronchoalveolar aspirate cultures or with serum antibody 1). These data show that in general, consumption of antibiotics in titers. In addition, L. pneumophila DNA was found both in these nations is low in comparison with that in Spain, where there serum samples obtained early (2–4 days) and later (10–15 days) has been a decrease from 31 DDD per 1,000 inhabitants per day after the onset of pneumonia. to 19 DDD per 1,000 inhabitants per day; these latter figures are Our results suggest that PCR assay of serum samples can conin the same range as those reported from Finland and Iceland tribute to the rapid diagnosis of legionella infection. Whether posi(figure 1). There have been few reports of antibiotic susceptibility tive results are due to legionella bacteriemia or to breakdown data from the Scandinavian countries in the medical literature, products (nucleic acids) that are present during the infection reand these data usually have an impact only when they describe mains to be elucidated. unexpected development of antibiotic resistance [3, 4]. The general trend during the past 10–20 years has been to report high frequencies of antibiotic resistance and the mechanisms of this resistance, but seldom the reasons for these high frequencies and how to avoid Peggy Matsiota-Bernard, Georgia Vrioni, them; the authors of these reports have had much easier and more and Charles Nauciel rapid access to high-impact journals than have authors reporting Laboratoire de Microbiologie, Hôpital Raymond Poincaré, low frequencies of antibiotic resistance. A few prospective multiGarches, France country surveys of selected human pathogens have been conducted and have unanimously shown that the Scandinavian countries and the United Kingdom have the lowest incidences of antibiotic resisReferences tance and that the southern European countries have the highest 1. Murdoch DR, Walford EJ, Jennings LC, et al. Use of the polyermase chain incidences of antibiotic resistance [5, 6]. reaction to detect Legionella DNA in urine and serum samples from Few data on antibiotic use in the southern European countries patients with pneumonia. Clin Infect Dis 1996;23:475–80. have been published, but the general impression from congresses, 2. Matsiota-Bernard P, Pitsouni E, Legakis N, Nauciel C. Evaluation of comreports, and the literature has been one of high antibiotic consumption mercial amplification kit for detection of Legionella pneumophila in and misuse, i.e., too much use and use of too many broad-spectrum clinical specimens. J Clin Microbiol 1994;32:1503–5. drugs. Recent studies have revealed that some of the multiply-resis3. Starnbach MN, Falkow S, Tompkins LS. Species-specific detection of Letant pathogens, e.g., Salmonella species, isolated daily in Scandinagionella pneumophila in water by DNA amplification and hybridization. J Clin Microbiol 1989;27:1257–61. vian clinics, are imported from abroad, mostly from Mediterranean