Organisms causing LRTI II - CG - FII AL 2022 - 15.07.2025.pptx

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1. Organisms causing lower respiratory tract infections - II Dr Chathuri Gunasekera Department of Medical Microbiology and Immunology Foundation II Module – AL 2022 batch 15.07.2025

2. Lesson outcomes Describe the basic microbiological features, source, mode of transmission and portal of entry (pathogenesis), virulence factors and pathology of the following pathogens Correlate the clinical symptoms and signs with the underlying pathology Outline the collection and transport of specimens and laboratory diagnosis of the infections caused by following pathogens Outline the principles of management of infections caused by following pathogens Identify the important epidemiological aspects  and explain strategies used to prevent/control infections in terms of elimination of source, interruption of transmission and host protection S. pneumoniae H. influenzae M. pneumoniae C. pneumoniae L. pneumophila Bordetella pertussis

3. Infectious diseases Aetiology Pathogenesis Clinical features Immunological response Laboratory diagnosis Treatment Epidemiology Prevention and Control

4. Whooping Cough (Pertussis) Aetiology : Bordetella pertussis

5. Pathogenesis Source: Exogenous pathogens from human patients Route of transmission: Inhalation of droplets into the respiratory tract

6. Pathogenesis Mainly non-invasive Attach to the cilia of the respiratory epithelial cells, multiply in the respiratory mucosa and produce toxins that paralyze the cilia and produces toxins that damage the ciliated epithelium of the respiratory tract Thus, pertussis is primarily a toxin-mediated disease. Cause inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions Until recently, scientists thought that B. pertussis did not invade the tissues. However, recent studies suggest that the bacteria are present in alveolar macrophages

7. Whooping Cough (Pertussis) – clinical features 3 phases catarrhal (like a rhinitis) paroxysmal (cough with inspiratory whoop) convalescent

8. Complications exhaustion malnutrition subconjunctival haemorrhages intracranial haemorrhage encephalopathy bronchiectasis

9. Laboratory diagnosis For aetiological diagnosis: Specimen: Per-nasal swab or nasopharyngeal aspirate Laboratory diagnosis methods: - Culture on special media - PCR to detect bacterial DNA Gram negative bacteria

10. Per-nasal swab Calcium alginate swabs on fine flexible wires are used. The patient's head is immobilized. The swab is gently inserted into the nostril until it reaches the posterior nares where it is left in place for a few seconds. If resistance is encountered during insertion of the swab, the other side should be tried as some persons have a deviated nasal septum It is best that a pernasal swab for pertussis diagnosis be inoculated directly onto the appropriate medium which is Bordet- Gengou medium.

11. Treatment/ management Antibiotics e.g. erythromycin - effective mainly in the catarrhal phase! (i.e. before paroxysms of cough begins) Symptomatic management at home, or in serious cases/ complicated cases – management at hospital

12. Epidemiology Was a common childhood illness Can occur in epidemics

13. Incidence of laboratory-confirmed pertussis cases, aged 1 year and older, England: 1998 to 2021*,**

14. Prevention and control Preventable to a certain extent by vaccination - killed pertussis bacteria (whole cell) in the pentavalent vaccine (P) The acellular pertussis vaccine ( aP ) - may be less effective as immunogenicity is low when compared to the former - Need to manage the patients with antibiotics (some practice prophylactic antibiotics to family members), rest, fluids, smaller meals, cleaner air, masks, cough etiquette, hand hygiene to prevent spread

15. THANK YOU!