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Clinical severity of Mycoplasma pneumoniae (MP) infection is associated with bacterial load in oropharyngeal secretions but not with MP genotype.

Nilsson, Anna LU ; Björkman, Per LU ; Welinder-Olsson, Christina; Widell, Anders LU and Persson, Kenneth LU (2010) In BMC Infectious Diseases 10(39).
Abstract
BACKGROUND: Disease severity in Mycoplasma pneumoniae (MP) infection could potentially be related to bacterial factors such as MP genotype (MP1 or MP2; distinguished by different adhesions proteins) or bacterial load in airway secretions. We have compared these parameters in patients who were hospitalized for MP pneumonia, with outpatients with mild MP disease. METHODS: MP bacterial load was measured by real-time PCR in 45 in- and outpatients ("clinical study group") in whom MP DNA had been detected in oropharyngeal secretions by PCR. In addition, genotype and phylogenetic relationships were determined. The phylogenetical assessment was done by partial DNA sequencing of the P1 gene on isolates from 33 patients in the clinical study-group... (More)
BACKGROUND: Disease severity in Mycoplasma pneumoniae (MP) infection could potentially be related to bacterial factors such as MP genotype (MP1 or MP2; distinguished by different adhesions proteins) or bacterial load in airway secretions. We have compared these parameters in patients who were hospitalized for MP pneumonia, with outpatients with mild MP disease. METHODS: MP bacterial load was measured by real-time PCR in 45 in- and outpatients ("clinical study group") in whom MP DNA had been detected in oropharyngeal secretions by PCR. In addition, genotype and phylogenetic relationships were determined. The phylogenetical assessment was done by partial DNA sequencing of the P1 gene on isolates from 33 patients in the clinical study-group where sufficient DNA was available. The assessment was further extended to isolates from 13 MP-positive family members and 37 unselected MP positive patients from the two subsequent years and two different geographical locations. In total 83 strains were molecular characterized. RESULTS: Mean MP loads were significantly higher in 24 hospitalized patients than in 21 outpatients (1600 vs. 170 genomic equivalents/microL, p = 0.009). This difference remained significant after adjustment for age and days between disease onset and sampling. Hospitalized patients also had higher C-reactive protein levels. Mean levels were 188 vs 20 mg/L (p = 0,001). The genotype assessment showed MP genotype 1 in 17 of the 33 sequenced strains from the clinical study-group, and type 2 in 16 of these patients. Within each genotype, sequence differences were minimal. No association between disease severity and MP genotype was observed. In the extended genotype assessment, MP1 was found in similar proportions. In family contacts it was found in 53% and among patients from the two subsequent years 53% and 40%. CONCLUSIONS: A higher MP bacterial load in throat secretions at diagnosis was associated with more advanced respiratory disease in patients, but MP genotype did not influence disease severity. Both MP genotypes co-circulated during recent outbreaks in Sweden. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
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in
BMC Infectious Diseases
volume
10
issue
39
publisher
BioMed Central
external identifiers
  • WOS:000275622700001
  • PMID:20184731
  • Scopus:77952297731
ISSN
1471-2334
DOI
10.1186/1471-2334-10-39
language
English
LU publication?
yes
id
e6efd653-4625-4550-b238-65d9aaff5939 (old id 1582863)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/20184731?dopt=Abstract
http://link.springer.com/article/10.1186%2F1471-2334-10-39
http://www.biomedcentral.com/1471-2334/10/39
date added to LUP
2010-04-07 10:23:40
date last changed
2017-02-05 04:37:07
@article{e6efd653-4625-4550-b238-65d9aaff5939,
  abstract     = {BACKGROUND: Disease severity in Mycoplasma pneumoniae (MP) infection could potentially be related to bacterial factors such as MP genotype (MP1 or MP2; distinguished by different adhesions proteins) or bacterial load in airway secretions. We have compared these parameters in patients who were hospitalized for MP pneumonia, with outpatients with mild MP disease. METHODS: MP bacterial load was measured by real-time PCR in 45 in- and outpatients ("clinical study group") in whom MP DNA had been detected in oropharyngeal secretions by PCR. In addition, genotype and phylogenetic relationships were determined. The phylogenetical assessment was done by partial DNA sequencing of the P1 gene on isolates from 33 patients in the clinical study-group where sufficient DNA was available. The assessment was further extended to isolates from 13 MP-positive family members and 37 unselected MP positive patients from the two subsequent years and two different geographical locations. In total 83 strains were molecular characterized. RESULTS: Mean MP loads were significantly higher in 24 hospitalized patients than in 21 outpatients (1600 vs. 170 genomic equivalents/microL, p = 0.009). This difference remained significant after adjustment for age and days between disease onset and sampling. Hospitalized patients also had higher C-reactive protein levels. Mean levels were 188 vs 20 mg/L (p = 0,001). The genotype assessment showed MP genotype 1 in 17 of the 33 sequenced strains from the clinical study-group, and type 2 in 16 of these patients. Within each genotype, sequence differences were minimal. No association between disease severity and MP genotype was observed. In the extended genotype assessment, MP1 was found in similar proportions. In family contacts it was found in 53% and among patients from the two subsequent years 53% and 40%. CONCLUSIONS: A higher MP bacterial load in throat secretions at diagnosis was associated with more advanced respiratory disease in patients, but MP genotype did not influence disease severity. Both MP genotypes co-circulated during recent outbreaks in Sweden.},
  articleno    = {39},
  author       = {Nilsson, Anna and Björkman, Per and Welinder-Olsson, Christina and Widell, Anders and Persson, Kenneth},
  issn         = {1471-2334},
  language     = {eng},
  number       = {39},
  publisher    = {BioMed Central},
  series       = {BMC Infectious Diseases},
  title        = {Clinical severity of Mycoplasma pneumoniae (MP) infection is associated with bacterial load in oropharyngeal secretions but not with MP genotype.},
  url          = {http://dx.doi.org/10.1186/1471-2334-10-39},
  volume       = {10},
  year         = {2010},
}