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BY Annerie Hattingh 26/08/09. Atypical Pneumonia. Introduction:. Pneumonia caused by atypical pathogens Typical pathogens usually includes: - Strep. pneumonia - Haemophilus pneumonia - Klebsiella pneumonia Does not respond to the usual antibiotics
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BY Annerie Hattingh 26/08/09 AtypicalPneumonia
Introduction: Pneumonia caused by atypical pathogens Typical pathogens usually includes: - Strep. pneumonia - Haemophilus pneumonia - Klebsiella pneumonia Does not respond to the usual antibiotics Causes a milder form of pneumonia (hence the term “walking pneumonia”) Characterized by a more drawn out coarse of symptoms
Legionella + SARS are exceptions to the above – both can be very severe infections Typical pneumonia can come on more quickly + with more severe early sx The arbitrary classification of typical vs. atypical pneumonia is of limited clinical value Literature now shows that a primary pathogen may co-exist with a secondary one, further blurring this distinction Introduction:
Introduction: Causes: “Classical” atypical pneumonias: 1.) Mycoplasma pneumonia 2.) Chlamydia pneumonia 3.) Legionella pneumonia
Introduction: Causes: Other micro-organisms that cause similar patterns of presentation: 1.) Chlamydia psittaci (exposure to birds) 2.) Coxiella burnetti (presenting as Q fever) 3.) Viral pneumonias - Influenza A - SARS - RSV - Adenoviridae - Varicella pneumonitis
Epidemiology: It is thought that the 3 main atypical pathogens might be implicated in up to 40% of CAP The precise incidence is not known Often not identified in clinical practice due to lack of readily available, reliable standardized tests to confirm dx By age 20, 50% of people in the USA have detectable levels of Antibodies to Chlamydia pneumonia
Risk Factors: Mycoplasma + Chlamydia spread by person-to-person contact - spread most common in closed populations e.g. schools, offices + military barracks Legionellae found most commonly in fresh water + man-made H2O systems
Risk Factors: - sources of contaminated H2O includes: * showers * condensers * whirlpools * cooling towers * respiratory equipment * air conditioning systems
Risk Factors: Other risk factors include: - young, healthy people - cigarette smoking - lung disease (like COPD) - weakened immune system (e.g. chronic steroid use or HIV)
Presentation: Mycoplasma pneumonia: Gram neg bacteria with no true cell wall Frequent cause of CAP in adults + children Prevalence in adults with pneumonia 2 – 30% Tends to be endemic, occurring @ 4-7yr intervals
Presentation: Mycoplasma pneumonia: Clinical Features: Symptomatic / asymp Gradual onset (over few days – weeks) Prodrome of “flu-like” symptoms
Presentation: Mycoplasma pneumonia: Clinical Features: Including: - headache - malaise - fever - non prod. Cough - sore throat
Presentation: Mycoplasma pneumonia: Clinical Features: Objective AbN on physical exam are minimal in contrast to the pt’s reported symptoms Present like many of common viral illnesses BUT persistence + progression of sx help to mark it out
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Can involve: CNS, Blood, Skin, CVS, Joints, GIT
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Neurological compl. Aseptic meningitis Cerebellar ataxia Transverse myelitis Peripheral neuropathy
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Neurological manifestations are infrequent Usually found in kids, if seen Associated with increased morbidity + mortality Antecedent resp. infection not always present
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Hematological compl. Hemolytic anemia IgM antibodies to erythrocyte membrane I antigen are present Produces a cold agglutinin response that leads to hemolysis
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Dermatological compl. Include rashes such as: Erythema multiforme Erythema nodosum Urticaria
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Cardiac involvement: Pericarditis Myocarditis
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: Joint involvent: (occationately described) Arthralgia Arthritis
Presentation: Mycoplasma pneumonia: Extrapulm. Manifestations/Complications: GIT symptoms: N + V Diarrhea Pancreatitis (rarely)
Presentation: Chlamydia: Genus Chlamydia includes 3 species that infect humans: - C. psittaci - C. trachomatis - C. pneumonia Small, coccoid, Gram neg bacteria that resemble rickettsiae
Presentation: Chlamydia: Chlamydia trachomatis - seen in newborn infants during delivery - has been ass. with pneumonia in adults
Presentation: Chlamydia: Chlamydia psittaci: Ornithosis is a systemic infection often acc. by pneumonia Common in birds + some domestic animals Pet shop employees + poultry workers @ risk Other systems involved: CNS (meningoencephalitis) + CVS (cult. neg. endocarditis)
Presentation: Chlamydia pneumonia: Prevalence varies by yr + geographic setting Causes 5-15% of all CAP Repeat infection is common Gradual onset which may show improvement before worsening again Incubation 3-4 weeks Initial non-specific URTI Sx lead to bronchitic/ pneumonic features
Presentation: Chlamydia pneumonia: Most infected remains quite well + asymptomatic Can cause prolonged, acute bronchitis with prod. cough Hoarseness + headache are common features Fever relatively uncommon Sx may drag on for weeks/months despite course of appropriate antibiotics
Presentation: Chlamydia pneumonia: Clinical severity usually caused by a secondary pathogen or co-existing illness e.g. diabetes Complications: Sinusitis, otitis media New onset asthma after acute infection Endocarditis, myocarditis
Presentation: Legionella pneumonia: Aerobic, motile, non-encapsulated, Gram neg bacilli Tends to be the most severe of the atypical pneumonias Focal outbreaks centered around poorly maintained air conditioning / humidification systems Incubation 2-10 days Initial mild headache, myalgia leading to fever, chills + rigors
Presentation: Legionella pneumonia: Minimally prod. cough Dyspnoea, pleuritic pain + hemoptysis are not uncommon Extra pulmonary legionellosis is rare but can be severe CVS most common extrapulm. site causing myocarditis, pericarditis + endocarditis Also pancreatitis, peritonitis, glomerulonephritis + focal neurological deficit
Diagnosis: CXR findings are usually non-specific and difficult to distinguish from other pneumonias Chest signs on examination minimal Rx of suspected atypical pneumonias should be empirical Cultures + serologic tests are not routinely available in laboratories
Diagnosis: A 53yr old patient with severe Legionella pneumonia. CXR shows dense consolidation in both lower lobes.
Diagnosis: A 40yr old patient with Chlamydia pneumonia. CXR shows multifocal, patchy consolidation in the right upper, middle and lower lobes.
Diagnosis: A 38yr old patient with Mycoplasma pneumonia. CXR shows a vague, ill defined opacity in the left lower lobe.
Management: Severe cases should be admitted Atypical pneumonias usually Rx as for other CAP, at least initially No evidence that routinely giving antibiotics active against atypical organisms leads to better outcomes in non-severe CAP
Management: Macrolides, such as Erythromycin, Clarithromycin + Azithromycin have been shown to be effective in the Rx of all 3 organisms Erythromycin tends to be less well tolerated + only few trails demonstrates its efficacy in the Rx of Legionella Severe Legionella infections may require rifampicin + a macrolide Tetracycline, Doxycycline + Fluoroquinolones are also effective Recommened duration of therapy usually 2-3 weeks
THE END QUESTIONS??
References: Shakeel Amanullah: Atypical Bacterial Pneumonia; eMed. March 2008. www.patient.co.uk: Atypical Pneumonias; Jan. 2007. www.thirdage.com: Encyclopedia – Atypical Pneumonia (Mycoplasma and Viral) (Walking Pneumonia); May 2008. Rosen’s Emergency Medicine Online: Community Acquired Pneumonia