Community-acquired pneumonia - Clinical and laboratory aspects of etiology
Hansen, Karin LU
(2026)
In Lund University, Faculty of Medicine Doctoral Dissertation Series
- Abstract
- Community-aqcuired pneumonia (CAP) is one of the most common infectious causes leading to hospitalization. Historically, Streptococcous pneumoniae has been the most common etiology in CAP and has therefor led to targeted interventions such as immunization in children, the elderly, and risk groups. Other important pathogens are Haemophilus influenzae, Mycoplasma pneumoniae and respiratory viruses.
The aim of this thesis was to investigate the etiology of CAP after introduction of PCV in the pediatric immunization programme as well as diagnostic sampling for respiratory pathogens, with a focus on the upper respiratory tract.
In Paper I, a comparison of nasopharyngeal aspirate (NPA) and flocked nasal swab (fNS) for testing... (More) - Community-aqcuired pneumonia (CAP) is one of the most common infectious causes leading to hospitalization. Historically, Streptococcous pneumoniae has been the most common etiology in CAP and has therefor led to targeted interventions such as immunization in children, the elderly, and risk groups. Other important pathogens are Haemophilus influenzae, Mycoplasma pneumoniae and respiratory viruses.
The aim of this thesis was to investigate the etiology of CAP after introduction of PCV in the pediatric immunization programme as well as diagnostic sampling for respiratory pathogens, with a focus on the upper respiratory tract.
In Paper I, a comparison of nasopharyngeal aspirate (NPA) and flocked nasal swab (fNS) for testing of respiratory pathogens was performed in 50 patients with acute respiratory symptoms, and we discovered that fNS was an adequate and well tolerated alternative to NPA for respiratory viruses.
Paper II-V include different sub-groups of a prospective cohort of 518 patients hospitalized with CAP.
In Paper II, we compared nasopharyngeal (NP) swabs with oropharyngeal (OP) swabs for respiratory pathogens in 484 patients. While NP detected more viruses, OP detected more bacteria (M. pneumoniae, S. pneumoniae and H. influenzae) but for all pathogens, cases were missed by using only one sample, and combined sampling of NP/OP would give the highest yield for viruses and Mycoplasma. For S. pneumoniae and H. influenzae, more research on the specificity of OP-samples is needed.
In Paper III, results were gathered from routine microbiologic tests, two different urinary antigen tests, and PCR from NP swabs in 518 patients, S. pneumoniae was the most common pathogen, followed by H. influenzae and viruses. Co-detections between viruses and bacteria was common. No differences was seen in symptoms our outcome when comparing bacterial, viral and viral-bacterial co-detection.
In Paper IV, we investigated the serotype distribution of pneumococcal CAP in hospitalized adults and found that 11% had a serotype included in PCV13 despite it being included in the child immunization vaccine programme. PCV15 and PCV20 would expand the serotype coverage in pneumococcal CAP.
In Paper V, we compared the clinical features of M. pneumoniae with S. pneumoniae. Clinical symptoms and radiology were insufficient in distinguishing between the to bacteria; inflammatory markers could be of some guidance but most importantly M. pneumoniae patients were three decades younger and more often experienced antibiotic failure. Liberal testing for Mycoplasma should be recommended for admitted patients with CAP younger than 50 years. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/8a773203-4256-4125-9d4b-2d9d7f94488a
- author
- Hansen, Karin
LU
- supervisor
-
- Kristian Riesbeck LU
- Jonas Ahl LU
- Anna C. Nilsson LU
- opponent
-
- Associate Professor Strålin, Kristoffer, Karolinska Institutet
- organization
- publishing date
- 2026
- type
- Thesis
- publication status
- published
- subject
- keywords
- pneumonia, etiology, diagnostic tests, pneumococcal serotypes, Mycoplasma pneumoniae, PCR, respiratory viruses, Community acquired pneumonia, pneumococcal serotypes, respiratory viruses, Mycoplasma pneumoniae, pcr, Sampling techniques
- in
- Lund University, Faculty of Medicine Doctoral Dissertation Series
- issue
- 2026:119
- pages
- 106 pages
- publisher
- Lund University, Faculty of Medicine
- defense location
- Kvinnoklinikens aula, Jan Waldenströms gata 47, Skånes Universitetssjukhus i Malmö . Join by Zoom: https://lu-se.zoom.us/j/65043431197
- defense date
- 2026-09-18 09:00:00
- ISSN
- 1652-8220
- ISBN
- 978-91-8021-917-4
- language
- English
- LU publication?
- yes
- id
- 8a773203-4256-4125-9d4b-2d9d7f94488a
- date added to LUP
- 2026-08-26 14:30:07
- date last changed
- 2026-08-27 07:36:33
@phdthesis{8a773203-4256-4125-9d4b-2d9d7f94488a,
abstract = {{Community-aqcuired pneumonia (CAP) is one of the most common infectious causes leading to hospitalization. Historically, Streptococcous pneumoniae has been the most common etiology in CAP and has therefor led to targeted interventions such as immunization in children, the elderly, and risk groups. Other important pathogens are Haemophilus influenzae, Mycoplasma pneumoniae and respiratory viruses.<br/><br/>The aim of this thesis was to investigate the etiology of CAP after introduction of PCV in the pediatric immunization programme as well as diagnostic sampling for respiratory pathogens, with a focus on the upper respiratory tract.<br/><br/>In Paper I, a comparison of nasopharyngeal aspirate (NPA) and flocked nasal swab (fNS) for testing of respiratory pathogens was performed in 50 patients with acute respiratory symptoms, and we discovered that fNS was an adequate and well tolerated alternative to NPA for respiratory viruses.<br/><br/>Paper II-V include different sub-groups of a prospective cohort of 518 patients hospitalized with CAP. <br/><br/>In Paper II, we compared nasopharyngeal (NP) swabs with oropharyngeal (OP) swabs for respiratory pathogens in 484 patients. While NP detected more viruses, OP detected more bacteria (M. pneumoniae, S. pneumoniae and H. influenzae) but for all pathogens, cases were missed by using only one sample, and combined sampling of NP/OP would give the highest yield for viruses and Mycoplasma. For S. pneumoniae and H. influenzae, more research on the specificity of OP-samples is needed. <br/><br/>In Paper III, results were gathered from routine microbiologic tests, two different urinary antigen tests, and PCR from NP swabs in 518 patients, S. pneumoniae was the most common pathogen, followed by H. influenzae and viruses. Co-detections between viruses and bacteria was common. No differences was seen in symptoms our outcome when comparing bacterial, viral and viral-bacterial co-detection. <br/><br/>In Paper IV, we investigated the serotype distribution of pneumococcal CAP in hospitalized adults and found that 11% had a serotype included in PCV13 despite it being included in the child immunization vaccine programme. PCV15 and PCV20 would expand the serotype coverage in pneumococcal CAP. <br/><br/>In Paper V, we compared the clinical features of M. pneumoniae with S. pneumoniae. Clinical symptoms and radiology were insufficient in distinguishing between the to bacteria; inflammatory markers could be of some guidance but most importantly M. pneumoniae patients were three decades younger and more often experienced antibiotic failure. Liberal testing for Mycoplasma should be recommended for admitted patients with CAP younger than 50 years.}},
author = {{Hansen, Karin}},
isbn = {{978-91-8021-917-4}},
issn = {{1652-8220}},
keywords = {{pneumonia; etiology; diagnostic tests; pneumococcal serotypes; Mycoplasma pneumoniae; PCR; respiratory viruses; Community acquired pneumonia; pneumococcal serotypes; respiratory viruses; Mycoplasma pneumoniae; pcr; Sampling techniques}},
language = {{eng}},
number = {{2026:119}},
publisher = {{Lund University, Faculty of Medicine}},
school = {{Lund University}},
series = {{Lund University, Faculty of Medicine Doctoral Dissertation Series}},
title = {{Community-acquired pneumonia - Clinical and laboratory aspects of etiology}},
url = {{https://lup.lub.lu.se/search/files/259125366/Avhandling_Karin_Hansen_LUCRIS.pdf}},
year = {{2026}},
}