Giuseppe
Emeritus
Real-time reverse-transcription PCR in the diagnosis of influenza A (H1N1)v in intensive care unit adult patients (BMC, letter, extract, edited)
[Source PDF Document: LINK. EDITED.]
Available online http://ccforum.com/content/13/6/428
Letter
Real-time reverse-transcription PCR in the diagnosis of influenza A (H1N1)v in intensive care unit adult patients
Concepci?n Gimeno 1,2 and David Navarro 2,3
1Microbiology Service, Consorcio Hospital General Universitario, Spain
2Department of Microbiology, School of Medicine, Valencia, Spain
3Microbiology Service, Hospital Cl?nico Universitario, Spain
Corresponding author: David Navarro, david.navarro@uv.es
Published: 7 December 2009 Critical Care 2009, 13:428 (doi:10.1186/cc8164)
This article is online at http://ccforum.com/content/13/6/428
? 2009 BioMed Central Ltd
See related research by Rello et al., http://ccforum.com/content/13/5/R148
ICU = intensive care unit; PCR = polymerase chain reaction; RT = reverse transcriptase.
Regarding the interesting article on novel influenza A (H1N1)v infection in intensive care adult patients with severe respiratory failure recently published in Critical Care [1], we should like to make the following comments.
The authors found that real-time RT-PCR for novel influenza A (H1N1)v virus in nasopharyngeal swabs on intensive care unit (ICU) admission was negative in four patients (12.5%) who later had a positive PCR result in respiratory secretions obtained at intubation, and concluded that ?a negative PCR result at admission should not exclude influenza A (H1N1)v due to the presence of false negative results in at least 10% cases? [1]. We of course understand what the authors meant.
In our opinion, however, this assumption is formally inaccurate, and is somewhat misleading, as it might be inferred that real-time RT-PCR gives at least 10% of false negative results in patients with overt symptomatic influenza requiring ICU admission.
The negative results reported by the authors cannot be considered true false negative RT-PCR results, as samples were not tested in parallel by a different assay yielding a positive result ? in fact, RT-PCR, which was used at participating centers, is currently the standard method for the diagnosis of influenza. Optimal sensitivity of RT-PCR and rapid antigen tests is achieved when upper tract respiratory specimens are collected within the first few days after the onset of symptoms, as appeared to be the case for the above-mentioned patients. Inappropriate sampling or specimen processing or suboptimal sensitivity of the PCR assay used most probably accounted for the negative results. No speculation on this matter can be made because the microbiological
information given to the readers was rather scarce.
The possibility of false negative RT-PCR results for influenza A (H1N1)v in severely ill patients requiring admission to ICUs is a very important issue that must be further investigated.
(...)
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[Source PDF Document: LINK. EDITED.]
Available online http://ccforum.com/content/13/6/428
Letter
Real-time reverse-transcription PCR in the diagnosis of influenza A (H1N1)v in intensive care unit adult patients
Concepci?n Gimeno 1,2 and David Navarro 2,3
1Microbiology Service, Consorcio Hospital General Universitario, Spain
2Department of Microbiology, School of Medicine, Valencia, Spain
3Microbiology Service, Hospital Cl?nico Universitario, Spain
Corresponding author: David Navarro, david.navarro@uv.es
Published: 7 December 2009 Critical Care 2009, 13:428 (doi:10.1186/cc8164)
This article is online at http://ccforum.com/content/13/6/428
? 2009 BioMed Central Ltd
See related research by Rello et al., http://ccforum.com/content/13/5/R148
ICU = intensive care unit; PCR = polymerase chain reaction; RT = reverse transcriptase.
Regarding the interesting article on novel influenza A (H1N1)v infection in intensive care adult patients with severe respiratory failure recently published in Critical Care [1], we should like to make the following comments.
The authors found that real-time RT-PCR for novel influenza A (H1N1)v virus in nasopharyngeal swabs on intensive care unit (ICU) admission was negative in four patients (12.5%) who later had a positive PCR result in respiratory secretions obtained at intubation, and concluded that ?a negative PCR result at admission should not exclude influenza A (H1N1)v due to the presence of false negative results in at least 10% cases? [1]. We of course understand what the authors meant.
In our opinion, however, this assumption is formally inaccurate, and is somewhat misleading, as it might be inferred that real-time RT-PCR gives at least 10% of false negative results in patients with overt symptomatic influenza requiring ICU admission.
The negative results reported by the authors cannot be considered true false negative RT-PCR results, as samples were not tested in parallel by a different assay yielding a positive result ? in fact, RT-PCR, which was used at participating centers, is currently the standard method for the diagnosis of influenza. Optimal sensitivity of RT-PCR and rapid antigen tests is achieved when upper tract respiratory specimens are collected within the first few days after the onset of symptoms, as appeared to be the case for the above-mentioned patients. Inappropriate sampling or specimen processing or suboptimal sensitivity of the PCR assay used most probably accounted for the negative results. No speculation on this matter can be made because the microbiological
information given to the readers was rather scarce.
The possibility of false negative RT-PCR results for influenza A (H1N1)v in severely ill patients requiring admission to ICUs is a very important issue that must be further investigated.
(...)
-
-----