History

Fact Explanation
Sore throat and hoarseness This is due to pharyngitis caused by the pathogen Chlamydia pneumoniae.[1] High affinity to the respiratory epithelium makes Chlamydophila pneumoniae a common etiological agent for pneumonia. [10] Hoarseness occurs due to the inflammation of pharynx and larynx. These symptoms present early and there is usually a subacute onset. There is a biphasic pattern with resolution of pharyngitis prior to development of pneumonia.[1]
Cough There is often a prolonged period of cough. This is usually a cough with scanty sputum production.[10] Cough is a defense mechanism in removing particles and pathogens. [2]
Fever The fever begins one week prior to respiratory symptoms, and disappears thereafter. This is due to the cytokines acting as endogenous pyrogens.[3]
Dyspnoea This is defined as the sense of difficulty in breathing. This occurs when alveoli gets obstructed with secretions and impairs gas exchange. [2] Usually this is a mild infection[1] so the patient is relatively comfortable.
Ear ache and head ache Purulent sinusitis and otitis media with effusion can be associated with pneumonia. [1] High affinity to the respiratory epithelium makes Chlamydophila pneumoniae a common etiological agent. [10]
Constitutional symptoms (malaise, lethargy etc.) These are due to inflammatory mediators released during the infection.These symptoms are more marked in Chlamydia pneumoniae infections.
Pleuritic type chest pain This is due to the inflammation of pleura which is pain sensitive.
Gastrointestinal symptoms Most patients develop symptoms such as vomiting and diarrhea [9] in comparison to other types of pneumonia.
Past history of COPD Common among patients with chronic obstructive pulmonary disease. [4],[10]
Exacerbation of Asthma (dyspnoea, wheezing, nocturnal cough) There is a increased incidence of exacerbation following C.pneumoniae infections.[4]
Contact history of patients with Chlamydia pneumonia. Humans are the known reservoir and transmission is from person to person via respiratory secretions.[1][10]
Extrapulmonary symptoms Erythema multiforme [5] ( well demarcated, small round lesions with erythema and target lesions) This is mediated by the deposition of IgM in the microvasculature of the skin.[6] Can cause an arthritis[5] with symptoms of Joint pain,swelling and erythema. [7]
Complications of Chlamydia pneumoniae Neurological complications are: meningoencephalitis (The patient is unconscious, or can have convulsions and respiratory arrest ), [8] Guillain-Barre´Syndrome (limb weakness, paresthesia, respiratory muscle paralysis, dysarthria) [8] Cardio vascular complications: Myocarditis[10][11] these patients can present with chest pain, dyspnoea, and sweating.
References
  1. KUO CC, JACKSON LA, CAMPBELL LA, GRAYSTON JT. Chlamydia pneumoniae (TWAR). Clin Microbiol Rev [online] 1995 Oct, 8(4):451-61 [viewed 05 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/8665464
  2. KUMAR, Parveen. CLARK, Michael.ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839
  3. BARRETT,Kim E. et al.ed. Ganong’s Review of Medical Physiology.New York:McGraw Hill.2010.pp285-286
  4. BLASI F. Atypical pathogens and respiratory tract infections. Eur Respir J [online] 2004 Jul, 24(1):171-81 [viewed 04 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15293621
  5. MEGRAN D, PEELING RW, MARRIE TJ. Chlamydia pneumoniae pneumonia: An evolving clinical spectrum Can J Infect Dis [online] 1995, 6(4):191-195 [viewed 05 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327926
  6. IMASHUKU S, KUDO N. Chlamydia Pneumoniae Infection-Associated Erythema Multiforme Pediatr Rep [online] , 5(2):35-37 [viewed 06 June 2014] Available from: doi:10.4081/pr.2013.e9
  7. RIZZO A, DOMENICO MD, CARRATELLI CR, PAOLILLO R. The role of Chlamydia and Chlamydophila infections in reactive arthritis. Intern Med [online] 2012, 51(1):113-7 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22214635
  8. KORMAN TM, TURNIDGE JD, GRAYSON ML. Neurological complications of chlamydial infections: case report and review. Clin Infect Dis [online] 1997 Oct, 25(4):847-51 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/9356800
  9. FILE TM JR, PLOUFFE JF JR, BREIMAN RF, SKELTON SK. Clinical characteristics of Chlamydia pneumoniae infection as the sole cause of community-acquired pneumonia. Clin Infect Dis [online] 1999 Aug, 29(2):426-8 [viewed 06 June 2014] Available from: doi:10.1086/520227
  10. CHOROSZY-KRóL I, FREJ-MąDRZAK M, HOBER M, SAROWSKA J, JAMA-KMIECIK A. Infections caused by Chlamydophila pneumoniae. Adv Clin Exp Med [online] 2014 Jan-Feb, 23(1):123-6 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24596014
  11. GNARPE H, GNARPE J, GäSTRIN B, HALLANDER H. Chlamydia pneumoniae and myocarditis. Scand J Infect Dis Suppl [online] 1997:50-2 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/9259082

Examination

Fact Explanation
Fever This is usually a low grade fever.[4] This is due to endogenous pyrogens released in the inflammatory process.[3]
Tachycardia This is defined as heart rate 100< beats per minutes. Only few patients has this sign[4] due to the mild nature of the disease. Hypoxia, Fever, release of catecholamines causes increase in the heart rate.[3]
Tachypnoea Hypercarbia and Hypoxia stimulate respiratory center to increase the rate of respiration.[3] Only few patients has this sign[4] due to the mild nature of the disease.
Pharyngeal erythema This is due to the inflammation of pharynx by the C.pneumoniae.Erythema is a classic feature of acute inflammation.[3]
Cervical lymphadenopathy The local lymph nodes gets inflamed when the lymph is carrying the pathogens to the draining node.This is a protective mechanism in infections.
Coarse crackles They are generated by the opening of collapsed airways.[2] Usually these features are found in seriously ill patients. This sign can be a common finding[4] but it doesn't prove the diagnosis.
Rhonchi These can be heard diffusely in both sides. The sound is generated by the turbulent airflow in narrowed airways.[2] This sign can be a common finding[4] but it doesn't prove the diagnosis.
Erythema multiforme These are polymorphous macular eruption , papules, and target lesions (central bullae or vesicle with concentric rash). The lesions in the extremities can be observed.[6] This can sometimes be associated with Chlamydia pneumonia.[1][5]
Ankle swelling, tenderness and erythema This is due to a reactive arthritis that can sometimes be associated with Chlamydia pneumonia.[1]
Neck stiffness This is a feature of Meningoencephalitis- [7] This is due to the spasm of neck muscles in passive flexion of the neck.
Low levels of GCS This is a feature of Meningoencephalitis- [7]
Papilloedema This is a feature of Meningoencephalitis- [7] It indicates raised intracranial pressure due to cerebral oedema.
Flaccid paralysis of the limbs with relative preservation of sensation This is a sign of complecated Chlamydia pneumonia (Guillain Barre Syndrome )[7]
Mitral regurgitation Myocarditis- Features of acute heart failure.
Fine basal crepitations Myocarditis- Features of acute heart failure.
References
  1. MEGRAN D, PEELING RW, MARRIE TJ. Chlamydia pneumoniae pneumonia: An evolving clinical spectrum Can J Infect Dis [online] 1995, 6(4):191-195 [viewed 05 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327926
  2. KUMAR, Parveen. CLARK, Michael.ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839
  3. BARRETT,Kim E. et al.ed. Ganong’s Review of Medical Physiology.New York:McGraw Hill.2010.pp285-286
  4. FILE TM JR, PLOUFFE JF JR, BREIMAN RF, SKELTON SK. Clinical characteristics of Chlamydia pneumoniae infection as the sole cause of community-acquired pneumonia. Clin Infect Dis [online] 1999 Aug, 29(2):426-8 [viewed 06 June 2014] Available from: doi:10.1086/520227
  5. IMASHUKU S, KUDO N. Chlamydia Pneumoniae Infection-Associated Erythema Multiforme Pediatr Rep [online] , 5(2):35-37 [viewed 06 June 2014] Available from: doi:10.4081/pr.2013.e9
  6. LEVIS JT. Dermatology Image: Erythema Multiforme Perm J [online] 2011, 15(4):76 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3267567
  7. KORMAN TM, TURNIDGE JD, GRAYSON ML. Neurological complications of chlamydial infections: case report and review. Clin Infect Dis [online] 1997 Oct, 25(4):847-51 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/9356800

Differential Diagnoses

Fact Explanation
Streptococcal Pneumonia Acute onset with flu like symptoms occur in the early stages. There is a productive cough with rusty colored sputum. Usually the fever is high and there may be chills as well.[1]
Mycoplasma Pneumoniae This is usually a mild disease with prominent extrapulmonary manifestations and complications such as haemolysis, erythema multiforme, hepatitis and meningoencephalitis.[1]
Legionella Pneumophila This can be a severe infection.Associated with inhalation of droplets in air condition systems. Neurological involvement , gastrointestinal involvement, and altered liver functions are differentiating features. [1]
Staphlococcus aureus Frequently follows viral respiratory tract infections.There is productive cough, haemoptysis and cavitations. [1]
Haemophilus influenzae This type is common in pre-existing structural lung disease(COPD,bronchiectasis)[1]
Chlamydia psittaci This is acquired from birds.Usually a milder form of pneumonia. [1]
Klebsiella Pneumonia This is common in alcoholics,poor dental hygiene, Diabetes and other co-morbidities. There is systemic derangement.[1]
Respiratory viruses There will be extrapulmonary symptoms such as malaise and myalgia. Mild form of Pneumonia can be found in majority of the patients.But some strains can cause severe respiratory compromise.
Fungal infections of the lung. Common in patients with immunosuppression and there will be a past history of cavitating lung diseases.
References
  1. KUMAR, Parveen. CLARK, Michael.ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839

Investigations - for Diagnosis

Fact Explanation
Full blood count Can indicate granulocytosis but this is nonspecific.[2]
C-Reactive protein This is a acute response proteins and in is elevated in infections.[2]
Blood cultures, gram staining and antibiatogram This is done as a basic test to exclude other bacterial pathogens.[2],[3]
chest X-ray This is done as a basic test to support clinical suspicion.[3] There are irregular segmented inflammatory infiltrates . The commonest site is the middle or lower lobes [4]
Antigen detection The test is done with TWAR antigen specific for C. pneumoniae. It can distinguish between antibodies in the IgM and IgG serum fractions,which helps in identifying recent from past infection and reinfection from primary infection.[1]
Serology C. pneumoniae specific MAbs have been useful in cell cultures. However, they are insensitive for detection in direct smears.Antigen detection by ELISA, has a poor sensitivity.[1]
PCR Several C. pneumoniae-specific primers have been used in PCR detection of organisms.[1]
Culture Cell lines for isolation are HL and HEp-2 . TWAR specific M Ab conjugated with fluorescein has greatly enhanced identification. An oropharyngial swab is used instead of sputum sample. [1]
References
  1. KUO CC, JACKSON LA, CAMPBELL LA, GRAYSTON JT. Chlamydia pneumoniae (TWAR). Clin Microbiol Rev [online] 1995 Oct, 8(4):451-61 [viewed 05 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/8665464
  2. KUMAR, Parveen. CLARK, Michael.ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839
  3. MANDELL L. A., WUNDERINK R. G., ANZUETO A., BARTLETT J. G., CAMPBELL G. D., DEAN N. C., DOWELL S. F., FILE T. M., MUSHER D. M., NIEDERMAN M. S., TORRES A., WHITNEY C. G.. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clinical Infectious Diseases [online] 2007 March, 44(Supplement 2):S27-S72 [viewed 05 June 2014] Available from: doi:10.1086/511159
  4. CHOROSZY-KRóL I, FREJ-MąDRZAK M, HOBER M, SAROWSKA J, JAMA-KMIECIK A. Infections caused by Chlamydophila pneumoniae. Adv Clin Exp Med [online] 2014 Jan-Feb, 23(1):123-6 [viewed 06 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24596014

Investigations - Fitness for Management

Fact Explanation
Plasma urea level Levels less than 7mmol/L indicate increased severity.[1]
Arterial blood gas Done if oxygen saturation is <94%[1] Pa O2 of <8kPa is a marker of severity of community acquired pneumonia.[1]
Albumin level Albumin level less than <35g/l is a marker of severity of community acquired pneumonia.[1]
References
  1. KUMAR, Parveen. CLARK, Michael.ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839

Investigations - Followup

Fact Explanation
Chest X ray Done after 6 weeks to assess the state of resolving of the pneumonia.[1]
References
  1. MANDELL L. A., WUNDERINK R. G., ANZUETO A., BARTLETT J. G., CAMPBELL G. D., DEAN N. C., DOWELL S. F., FILE T. M., MUSHER D. M., NIEDERMAN M. S., TORRES A., WHITNEY C. G.. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clinical Infectious Diseases [online] 2007 March, 44(Supplement 2):S27-S72 [viewed 05 June 2014] Available from: doi:10.1086/511159

Management - General Measures

Fact Explanation
Decide the treatment setting Depends on severity-of-illness scores, assessed by the CURB-65 criteria ( includes confusion, uremia, respiratory rate, low blood pressure and age 65 years or greater; each component carries one point). [1]
Oxygen This is to improve oxygen saturation of the blood. In a patient with COPD should be given between 88%-92% because the hypoxic drive should not be abolished.[1]
Intravenous fluids Is given in hypotensive patients to replace volume depletion.[1]
Analgesia and antipyretics This improves well being of the patient.It helps to reduce pleuritic pain and improve breathing and sputum clearance.[1]
Physiotherapy This is needed only if there is sputum retention[1]
Thromboprophylaxis with subcutaneous heparin and TED stockings This can be considered in patients hospitalized for more than 12hs.[1]
References
  1. KUMAR Parveen, CLARK Michael ed.Respiratory disease. KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839

Management - Specific Treatments

Fact Explanation
Tetracycline These are broad-spectrum antibiotics that inhibit protein synthesis of the pathogens.[1] It is given 500 mg four times daily for 14 days[2]
Doxycycline These are broad-spectrum antibiotics that inhibit protein synthesis of the bacteria[1].It is given at a dose of 100 mg twice daily for 14 days[2]
Erythromycin This is a bactericidal drug[1].It is used as 500 mg four times daily for 14 days.[2]
Management of a patient with high mortality ( example: hospitalized patient with CURB 65 score over 3) This is empirical therapy.The rout of admission is by intravenous line. Intravenous antibiotics can be given to hospitalized patients( CURB 65 score of 2 ) who can't take oral medications. Alternatively: IV Ceftriaxone and IV Clarythromycin or Benzylpenicillin and Levofloxacin.[3] Co-amoxiclav acts againsts gram positive organisms and gram negative cocci. It is resistant to beta lactamases.[1] Clarythromycin has a bactericidal action.[1] Ceftriaxone is a third generation cephalosporin and it they are broad-spectrum antibiotics with bactericidal action. Benzylpenicillin acts againsts gram positive organisms and gram negative cocci. [1] Levofloxacin is a fluoroquinolone and it inhibits bacterial DNA synthesis.It is Baceristatis. It has a more gram negative coverage.[1]
References
  1. KATZUNG Bertam G, MASTERS Susan B, TREVOR Anthony J ed.Basic & Clinical pharmacology.12th ed.New York:McGraw Hill.2012.pp810-813
  2. KUO CC, JACKSON LA, CAMPBELL LA, GRAYSTON JT. Chlamydia pneumoniae (TWAR). Clin Microbiol Rev [online] 1995 Oct, 8(4):451-61 [viewed 05 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/8665464
  3. KUMAR Parveen, CLARK Michael ed.Respiratory disease.KUMAR & CLARK'S Clinical Medicine.8th ed.London:SAUNDERS ELSEVIER.2012.PP.833-839