Mycoplasma pneumoniae
Related Subjects:Asthma
|Acute Severe Asthma
|Exacerbation of COPD
|Pulmonary Embolism
|Cardiogenic Pulmonary Oedema
|Pneumothorax
|Tension Pneumothorax
|Respiratory (Chest) infections Pneumonia
|Fat embolism
|Hyperventilation Syndrome
|ARDS
|Respiratory Failure
|Diabetic Ketoacidosis
๐ About
- ๐ซ Mycoplasma pneumoniae is a common cause of โwalking pneumoniaโ โ typically mild but with significant extrapulmonary complications.
- โณ Incubation period: 2โ3 weeks.
- ๐ฉโ๐ฆ Affects mainly children & young adults (5โ20 years); outbreaks in close communities.
๐ฌ Characteristics
- ๐ Small, Gram-negative, but lacks a cell wall โ key feature.
- โ๏ธ Requires enriched media; very slow-growing (โfried eggโ colonies in culture).
- ๐ฌ๏ธ Aerobic or facultative anaerobe.
- โ Resistant to ฮฒ-lactam antibiotics (penicillin, cephalosporins) due to absent cell wall.
๐ Source & Transmission
- Spread via respiratory droplets (coughs, close contact).
- ๐ Outbreaks: schools, universities, military barracks, families.
๐ฉบ Clinical Features
- Respiratory: URTI, tracheobronchitis, community-acquired pneumonia (often mild), bullous myringitis ๐.
- Skin: Erythema multiforme, StevensโJohnson syndrome.
- Vascular: Raynaudโs phenomenon, hypercoagulability โ strokes & thrombosis.
- Neurological: Aseptic meningitis, encephalitis, GuillainโBarrรฉ syndrome (GBS), transverse myelitis.
- Joints: Migratory arthralgias/arthritis.
๐งช Investigations
- โ๏ธ Cold agglutinins: IgM autoantibodies against RBC โIโ antigen โ haemolysis (positive in ~50%).
- ๐ Other causes of cold agglutinins: EBV (anti-i), CMV, lymphomas.
- ๐งช Direct Coombs test: may be positive; โ reticulocytes if haemolysis present.
- ๐ฉป CXR: โChest out of proportionโ โ widespread infiltrates with only mild symptoms.
๐ Management
- โ No effect from ฮฒ-lactams (penicillin, cephalosporins).
- โ
Use macrolides (clarithromycin, azithromycin, erythromycin) OR tetracyclines (doxycycline).
- โ ๏ธ Avoid tetracyclines in pregnancy and children <12 years.
- ๐ Course: 7โ14 days.
- โ ๏ธ Drug interaction: Erythromycin โ theophylline levels โ risk of toxicity.
