MGEM2013 Resp Disease Resp Pathogens 22-23 Part I .pptx

MGEM2013 Respiratory pathogens lecture PART I – Upper and lower respiratory infections Learning objectives Recognise the demographics of respiratory infections and the differences between upper and lower respiratory tract infections Describe the spectrum of microorganisms causing respiratory tra...

MGEM2013 Respiratory pathogens lecture PART I – Upper and lower respiratory infections Learning objectives Recognise the demographics of respiratory infections and the differences between upper and lower respiratory tract infections Describe the spectrum of microorganisms causing respiratory tract infection Global and UK demographics Why are respiratory diseases amongst the top of major causes of death worldwide? Facts on respiratory Respiratory tract as main portal for pathogen entry Approx. 10,000 litre air taken in each day Potentially filled with infectious particles - viral, bacterial and fungal Some pathogens cause mild infections – common cold, sore throat Some result in serious clinical outcomes with high mortality Lower respiratory infections ranked 4th cause of death Respiratory Tract Infections Upper respiratory tract infection (URTI) Lower respiratory tract infection (LRTI) Respiratory Tract Infections Upper respiratory tract infection (URTI): Mainly viral Secondary complications – bacterial / fungal infections are common Lower respiratory tract infection (LRTI) Can be bacterial, viral or fungal Most common bacterial infections vs normal flora Normal flora / Microbiota Respiratory Tract Infections Upper respiratory tract infection (URTI): Mainly viral Secondary complications – bacterial / fungal infections are common Lower respiratory tract infection (LRTI) Can be bacterial, viral or fungal Upper Respiratory Tract Infections Common cause of morbidity, approx. 9% of all GP visits. Mostly self-limiting, occasionally poor outcomes (e.g. Diphtheria) Symptoms overlap with LRTIs Viral and bacterial URTI produce the similar clinical pattern of illness Common cold Symptoms: Rhinorrhoea, sneezing, nasal obstruction, sore throat (pharyngitis), fever Rhinoviruses 25 and 50% of colds in adults. Coronaviruses More than 10%. Other: Parainfluenza viruses Respiratory syncytial virus Adenoviruses Influenza viruses All of these viruses show seasonal variations in incidence Sinusitis Infection of the sinuses, characterised by: Facial pain Nasal obstruction Nasal discharge Post-nasal drip from sinusitis is irritating to the larynx and may cause a persistent cough. What causes sinusitis? Acute sinusitis most often follows a common cold (viral causes or post viral bacterial complications) Common bacterial agents responsible for acute sinusitis: Streptococcus pneumoniae Haemophilus influenzae Staphylococcus aureus Streptococcus pyogenes (Group A) – less common Pseudomonas aeroginosa Also other enteric bacteria such as E coli – as cross-contamination in children Acute sinusitis - Infections impair the ciliary activity and increased mucous secretions. Causing obstruction impedes drainage. pus further irritates the mucosal lining causing more oedema, epithelial destruction and sinus obstruction. Pharyngitis and laryngitis Most cases are due to viral infections associated with the common cold Also can be bacterial infection : Streptococcus pyogenes (Strep throat) Others: Fungal – caused by candida albicans (Thrush) mainly in immunocompromised Scarlet fever Caused by Strep pyogenes through inhalation, skin contact or oral route Leading cause of death in children in the early 20th century Most commonly affects children between 5 to 15 y.o. Fever followed by rough red rash over trunk and abdomen then spreads to entire body Accompanied by pyrexia, lymphadenopathy, aches and nausea Tonsillitis Mainly by common strains of viruses Infectious mononucleosis - caused by Epstein Barr virus (EBV) Primary infection becomes latent Reactivation Persistent infection Lymphoma Nasopharyngeal cancer Bacterial tonsillitis – most common Strep pyogenes EBV transformation of B / T & epithelial cells EBV infections can lead to Lymphoma and Nasopharyngeal cancer Life-threatening upper respiratory infection Diphtheria Caused by Corynebacterium diphtheriae Gram-positive, rod-shaped bacteria Irregular, club-shaped or V-shaped arrangements Toxin induces epithelial necrosis embedded in fibrin and white cell infiltrates forming pseudomembrane in trachea Can be fatal - multisystem toxaemia and myocarditis Respiratory Tract Infections Upper respiratory tract infection (URTI): Mainly viral Secondary complications – bacterial / fungal infections are common Lower respiratory tract infection (LRTI) Can be bacterial, viral or fungal Lower Respiratory Tract Infections Less common that URTIs but often more severe Tracheitis, bronchitis, bronchiolitis and pneumonia Despite antibiotics use, high mortality Very common cause of nosocomial infections ranking third after urinary tract infections and surgical wound infections Tracheitis Rarely occurring in adults, affects primarily infants and children Symptoms: Severe coughing Nasal flaring Breathing difficulties Cyanosis Viral or bacterial Bacterial causes: Most common Staph aureus including MRSA Strep pyogenes Strep pneumoniae Haemophilus influenzae Moraxella catarrhalis Enteric bacteria Bronchitis Symptoms: coughing up mucus wheezing shortness of breath chest discomfort Cough lasting few weeks Primarily viral Occasionally bacterial Strep pneumoniae Haemophilus influenzae catarrhalis Moraxella Bronchioliti s Viral causes (RSV – most common, Influenza, parainfluenza, Rhinovirus) Affecting infants up to 2 y.o. Preceded by viral URTIs Cough, wheezing followed by respiratory distress Pneumonia Inflammation of the lung affecting primarily the alveoli but also the bronchioles and bronchi Pathology includes build up of fluid in the form of mucus and / or blood in the alveoli Symptoms Productive or dry cough, chest pain, fever, and troubles during breathing People at risk include: Infants and young children Over 65 With long-term heart, lung and kidney diseases, or diabetes or cancer Smokers / alcohol in excess Immunocompromised Hospitalised Whooping cough - Pertussis Caused by Gram negative coccobacilli Bordetella pertussis Re-emergent as a serious respiratory illness affecting infants and children but also occasionally young adults Toxin similar to cholera toxin Explosive cough as disease develops into paroxysmal stage (series of consecutive bursts of cough with increasing intensity) Rapid exhaustion Cyanosis and Convulsion List of common bacterial fungal and viral causes LRTIs Bacteria Viruses Streptococcus pneumoniae Influenza Streptococcus pyogenes (Grp A) Parainfluenza Streptococcus agalactiae (Grp B) Cytomegalovirus Staphylococcus aureus Adenovirus Bacillus anthracis Epstein-Barr Virus Other Bacillus sp. Herpes Simplex Virus Nocardia sp. Varicella-Zoster Enterobacteriaceae Coxsackievirus Pseudomonas aeruginosa Measles Acinetobacter sp. Rhinovirus Burkholderia pseudomallei Respiratory Syncytial Virus Burkholderia mallei Fungi Yersinia pestis Aspergillus sp. Francisella tularensis Mucorales sp Hemophilus influenzae Candida sp. Bordetella pertussis Histoplasma capsulatum Neisseria meningitidis Blastomyces dermatitidis Legionella pneumophila Cryptococcus neoformans Legionella-like bacteria Coccidioides immitis Bacteroides melaninogenicus Paracoccidioides brasiliensis Fusobacterium nucleatum Pneumocystis carinii Peptostreptococcus sp. Parasites-Protozoa Peptococcus sp. Plasmodium falciparum Actinomyces sp. Entamoeba histolytica Mycobacterium tuberculosis Toxoplasma gondii Other Mycobacterium sp. Leishmania donovani Mycoplasma pneumoniae Parasites-Nematodes Branhamella catarrhalis Ascaris lumbricoides Chlamydia trachomatis Toxocara sp. Chlamydophila psittaci Ancyclostoma duodenale Chlamydophila pneumoniae Parasites-Cestodes Coxiella burnetii (Q-fever) Echinococcus granulosus Summary Upper Respiratory Tract Infections Common cause of morbidity, approx. 9% of all GP visits. Mostly self-limiting, occasionally poor outcomes (e.g. Diphtheria) Symptoms overlap with LRTIs Viral and bacterial URTI produce the similar clinical pattern of illness Lower Respiratory Tract Infections Less common that URTIs but often more severe Tracheitis, bronchitis, bronchiolitis and pneumonia Despite antibiotics use, high mortality Very common cause of nosocomial infections ranking third after urinary tract infections and surgical wound infections Tracheitis – bacterial / viral Bronchitis – primarily viral, occasionally bacterial Bronchiolitis – viral, preceded by URTIs Pneumonia – viral, bacterial, atypical bacterial, fungal