Atypical Pneumonia

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AtypicalPneumonia

• BY
• Annerie Hattingh
• 26/08/09

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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

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Introduction

• 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

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Introduction

• Causes
• Classical atypical pneumonias
• 1.) Mycoplasma pneumonia
• 2.) Chlamydia pneumonia
• 3.) Legionella pneumonia

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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

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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

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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

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Risk Factors

• - sources of contaminated H2O includes
• showers
• condensers
• whirlpools
• cooling towers
• respiratory equipment
• air conditioning systems

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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)

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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 _at_ 4-7yr intervals

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Presentation

• Mycoplasma pneumonia
• Clinical Features
• Symptomatic / asymp
• Gradual onset (over few days weeks)
• Prodrome of flu-like symptoms

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Presentation

• Mycoplasma pneumonia
• Clinical Features
• Including - headache
• - malaise
• - fever
• - non prod. Cough
• - sore throat

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Presentation

• Mycoplasma pneumonia
• Clinical Features
• Objective AbN on physical exam are minimal in
  contrast to the pts reported symptoms
• Present like many of common viral illnesses BUT
  persistence progression of sx help to mark it
  out

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• Can involve CNS, Blood, Skin, CVS, Joints, GIT

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• Neurological compl.
• Aseptic meningitis
• Cerebellar ataxia
• Transverse myelitis
• Peripheral neuropathy

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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

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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

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• Dermatological compl.
• Include rashes such as
• Erythema multiforme
• Erythema nodosum
• Urticaria

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• Cardiac involvement
• Pericarditis
• Myocarditis

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• Joint involvent (occationately described)
• Arthralgia
• Arthritis

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Presentation

• Mycoplasma pneumonia
• Extrapulm. Manifestations/Complications
• GIT symptoms
• N V
• Diarrhea
• Pancreatitis (rarely)

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Presentation

• Chlamydia
• Genus Chlamydia includes 3 species that infect
  humans - C. psittaci
• - C. trachomatis
• - C. pneumonia
• Small, coccoid, Gram neg bacteria that resemble
  rickettsiae

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Presentation

• Chlamydia
• Chlamydia trachomatis - seen in newborn infants
• 
  during delivery
• - has
  been ass. with
• 
  pneumonia in adults

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Presentation

• Chlamydia
• Chlamydia psittaci
• Ornithosis is a systemic infection often acc. by
  pneumonia
• Common in birds some domestic animals
• Pet shop employees poultry workers _at_ risk
• Other systems involved CNS (meningoencephalitis)
  CVS (cult. neg. endocarditis)
  

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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

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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

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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

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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

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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

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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

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Diagnosis

• A 53yr old patient with severe
• Legionella pneumonia.
• CXR shows dense consolidation in both lower
  lobes.

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Diagnosis

• A 40yr old patient with Chlamydia pneumonia.
• CXR shows multifocal, patchy consolidation in the
  right upper, middle and lower lobes.

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Diagnosis

• A 38yr old patient with Mycoplasma pneumonia.
• CXR shows a vague, ill defined opacity in the
  left lower lobe.

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Cause of pneumonia Mycoplasma pneumoniae Legionella pneumophila Chlamydophila (Chlamydia) pneumoniae
Blood tests May be raised WCC or rarely evidence of haemolytic anaemia. ESR may be elevated. Serology titres and complement fixation tests/ELISA can help to confirm the diagnosis. FBC may show left shift. Severe cases may have DIC evident on FBC/INR. Hyponatraemia may occur due to syndrome of inappropriate ADH secretion. Urea/creatinine can be raised if complicated by renal failure or dehydration. LFTs often non-specifically deranged. CK may be elevated in rhabdomyolysis. Serological tests on blood or urine may be used to confirm diagnosis. Usually non-specific and unhelpful. Serology titres or polymerase chain reaction tests may be used to confirm the diagnosis.
CXR Usually single lower-lobe bronchopneumonia pattern with lobar consolidation rare. Other possible patterns include atelectasis, nodular infiltration akin to TB/sarcoidosis, hilar adenopathy and rarely pleural effusion. 50 have pleural effusion. Patchy alveolar infiltrates may be seen. CXR can take up to 4 months to return to normal and may initially progress despite therapy. Usually lower-lobe single subsegmental infiltrate. Pleural effusion found in up to a quarter of cases. Can progress to ARDS. CXR changes may take up to 3 months to resolve.
ABGs may be checked to assess respiratory function in acute, severe cases of community-acquired pneumonia. Similarly, blood cultures should be taken to aid subsequent microbiological diagnosis. In cases of atypical pneumonia where there is evidence of focal or global cerebral impairment, an LP should be considered. ABGs may be checked to assess respiratory function in acute, severe cases of community-acquired pneumonia. Similarly, blood cultures should be taken to aid subsequent microbiological diagnosis. In cases of atypical pneumonia where there is evidence of focal or global cerebral impairment, an LP should be considered. ABGs may be checked to assess respiratory function in acute, severe cases of community-acquired pneumonia. Similarly, blood cultures should be taken to aid subsequent microbiological diagnosis. In cases of atypical pneumonia where there is evidence of focal or global cerebral impairment, an LP should be considered. ABGs may be checked to assess respiratory function in acute, severe cases of community-acquired pneumonia. Similarly, blood cultures should be taken to aid subsequent microbiological diagnosis. In cases of atypical pneumonia where there is evidence of focal or global cerebral impairment, an LP should be considered.
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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

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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

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THE END QUESTIONS??
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References

1. Shakeel Amanullah Atypical Bacterial Pneumonia
   eMed. March 2008.
2. www.patient.co.uk Atypical Pneumonias Jan.
   2007.
3. www.thirdage.com Encyclopedia Atypical
   Pneumonia (Mycoplasma and Viral) (Walking
   Pneumonia) May 2008.
4. Rosens Emergency Medicine Online Community
   Acquired Pneumonia