Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs

Streptococcus pneumoniae are common bacterial pathogens that can cause a range of diseases in humans and animals. This study attempts to clarify the course and consequences of pneumonia caused by this bacterial infection. A total of 6 male un-weaned lambs aged between 1 to 2 months and weighing...

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Main Authors: Abbas A Hamzah, Zainab I Ibrahim
Format: Article
Language:English
Published: University of Baghdad, College of Veterinary Medicine 2024-12-01
Series:The Iraqi Journal of Veterinary Medicine
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Online Access:https://www.jcovm.uobaghdad.edu.iq/index.php/Iraqijvm/article/view/1733
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author Abbas A Hamzah
Zainab I Ibrahim
author_facet Abbas A Hamzah
Zainab I Ibrahim
author_sort Abbas A Hamzah
collection DOAJ
description Streptococcus pneumoniae are common bacterial pathogens that can cause a range of diseases in humans and animals. This study attempts to clarify the course and consequences of pneumonia caused by this bacterial infection. A total of 6 male un-weaned lambs aged between 1 to 2 months and weighing 5 to 7 kg were subjected to S. pneumoniae strain ATCC 6303 serotype 3 at ‎2×106 ‎CFU/mL by inhalation to induce pneumonia. Pneumonic clinical signs were ‎monitored daily throughout the study period. The blood samples were collected from all animal groups at day zero before pneumoniae induction and 3, 6, and 14 days post infection  for total and differential white blood cell count ‎(WBCs) and tumor necrosis factor-alpha (TNF-α) assessments. Additionally, on days 6 and 14 post-exposure, trachea and lung tissue samples were harvested for macroscopic and microscopic pathological changes evaluation. The results showed that there was a significant increase (P<0.001) in total WBC counts from day 3 post-exposure and maintaining elevated levels on days 6 and 14 compared to day zero. Differential WBC counts showed an early, significant rise in neutrophils, with sustained ‎elevation in lymphocytes and monocytes. TNF-α‎ levels significantly elevated on day 3‎ and gradually declined by day 14‎ post-exposure (P<0.001). On day 6 post-exposure, the gross pathological changes in the lung showed pulmonary edema, and emphysema, with mild to moderate lung congestion and emphysematous changes observed on day 14 post-exposure. Histopathologically, severe erosion and necrosis in the trachea and bronchus epithelium, along with inflammation in adjacent mucosa and submucosa, accompanied by focal inflammatory infiltration and emphysema in the lung by day 6 post-exposure, were observed. By day 14, these changes progressed to marked epithelial vacuolation and necrosis in the trachea, with lung sections revealing perivascular cuffing, peri bronchiolitis, mild bronchiectasis, atelectasis, and alveolar collapse. This study is attempt for a better understanding of S. pneumoniae infection in lamb and contributing to the development of preventive and management strategies in Iraq‎‎‎.
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spelling doaj-art-5b25288662de4beabaf3b047f0fe29472025-01-09T20:24:47ZengUniversity of Baghdad, College of Veterinary MedicineThe Iraqi Journal of Veterinary Medicine1609-56932410-74092024-12-0148210.30539/pq3zsq53Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in LambsAbbas A Hamzah0https://orcid.org/0009-0006-9145-1609Zainab I Ibrahim1https://orcid.org/0009-0005-2586-0386Department of Pathology and Poultry Disease, College of Veterinary Medicine, University of Baghdad, Baghdad, IraqDepartment of Pathology and Poultry Disease, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq Streptococcus pneumoniae are common bacterial pathogens that can cause a range of diseases in humans and animals. This study attempts to clarify the course and consequences of pneumonia caused by this bacterial infection. A total of 6 male un-weaned lambs aged between 1 to 2 months and weighing 5 to 7 kg were subjected to S. pneumoniae strain ATCC 6303 serotype 3 at ‎2×106 ‎CFU/mL by inhalation to induce pneumonia. Pneumonic clinical signs were ‎monitored daily throughout the study period. The blood samples were collected from all animal groups at day zero before pneumoniae induction and 3, 6, and 14 days post infection  for total and differential white blood cell count ‎(WBCs) and tumor necrosis factor-alpha (TNF-α) assessments. Additionally, on days 6 and 14 post-exposure, trachea and lung tissue samples were harvested for macroscopic and microscopic pathological changes evaluation. The results showed that there was a significant increase (P<0.001) in total WBC counts from day 3 post-exposure and maintaining elevated levels on days 6 and 14 compared to day zero. Differential WBC counts showed an early, significant rise in neutrophils, with sustained ‎elevation in lymphocytes and monocytes. TNF-α‎ levels significantly elevated on day 3‎ and gradually declined by day 14‎ post-exposure (P<0.001). On day 6 post-exposure, the gross pathological changes in the lung showed pulmonary edema, and emphysema, with mild to moderate lung congestion and emphysematous changes observed on day 14 post-exposure. Histopathologically, severe erosion and necrosis in the trachea and bronchus epithelium, along with inflammation in adjacent mucosa and submucosa, accompanied by focal inflammatory infiltration and emphysema in the lung by day 6 post-exposure, were observed. By day 14, these changes progressed to marked epithelial vacuolation and necrosis in the trachea, with lung sections revealing perivascular cuffing, peri bronchiolitis, mild bronchiectasis, atelectasis, and alveolar collapse. This study is attempt for a better understanding of S. pneumoniae infection in lamb and contributing to the development of preventive and management strategies in Iraq‎‎‎. https://www.jcovm.uobaghdad.edu.iq/index.php/Iraqijvm/article/view/1733Streptococcus pneumoniaerespiratory infectionimmunopathologylamb
spellingShingle Abbas A Hamzah
Zainab I Ibrahim
Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
The Iraqi Journal of Veterinary Medicine
Streptococcus pneumoniae
respiratory infection
immunopathology
lamb
title Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
title_full Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
title_fullStr Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
title_full_unstemmed Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
title_short Immunopathological Changes of Streptococcus pneumoniae Causing Respiratory Infection in Lambs
title_sort immunopathological changes of streptococcus pneumoniae causing respiratory infection in lambs
topic Streptococcus pneumoniae
respiratory infection
immunopathology
lamb
url https://www.jcovm.uobaghdad.edu.iq/index.php/Iraqijvm/article/view/1733
work_keys_str_mv AT abbasahamzah immunopathologicalchangesofstreptococcuspneumoniaecausingrespiratoryinfectioninlambs
AT zainabiibrahim immunopathologicalchangesofstreptococcuspneumoniaecausingrespiratoryinfectioninlambs