1
Fifth stage
Pediatric
) Respiratory )
Lec-5
د.أ
ثل
21/11/2016
Mycoplasma pneumoniae
EPIDEMIOLOGY
• Mycoplasma pneumoniae causing respiratory infections in school-age children and
young adults.
• The incubation period is 2-3 wk
• Immunity after infection is not long lasting.
• Asymptomatic carriage after infection can last up to 4 mo despite antibiotic therapy
and may contribute to prolonged outbreaks.
CLINICAL MANIFESTATIONS
• Tracheobronchitis and pneumonia are the most commonly recognized clinical
syndromes associated with M. pneumoniae infection.
• Although the onset of illness may be abrupt, it is usually characterized by gradual
onset of headache, malaise, fever, and sore throat, followed by progression of lower
respiratory symptoms, including hoarseness and nonproductive cough.
• Coryza or gastrointestinal complaints are unusual with M. pneumoniae pneumonia
and usually suggest a viral etiology.
• Although the clinical course in untreated patients is variable, cough, the clinical
hallmark of M. pneumoniae infection, usually worsens during the 1st wk of illness,
and symptoms generally resolve within 2 wk. Cough can last up to 4 wk and may be
accompanied by wheezing. Patients generally recover without complications.
• Chest exam is often unrevealing, even in patients with severe cough. There may be
no auscultative or percussive findings or only minimum dry rales.
• Clinical findings are often less severe than suggested by the patient chest radiograph,
that is why term “walking pneumonia”
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• CXR: interstitial or bronchopneumonic, involve mainly the lower lobes. Bilateral
diffuse infiltrates, lobar pneumonia or hilar lymphadenopathy can occur in up to 30%
. Pleural effusions may occur.
• The WBC and differential counts are usually normal.
•
ESR is often elevated.
Hilar involvement
Lower lobe pn
Pleural effusion
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Other respiratory illnesses caused occasionally by M. pneumoniae
include:
• Pharyngitis
• Sinusitis
• Otitis media
• Croup
• Bronchiolitis
• M. pneumoniae is a common trigger of wheezing in asthmatic children
Extrapulmonary Disease:
• CNS disease, as encephalitis, transverse myelitis, aseptic meningitis, Guillain-Barré
syndrome.
• Dermatologic disease, which includes a variety of exanthemas, most notably
maculopapular rash urticaria, erythema multiforme or Stevens-Johnson syndrome
(SJS), & erythema nodosum.
• Hematologic abnormalities, hemolytic anaemia, thrombocytopenia, aplastic anemia,
and coagulation defects occur occasionally.
• Arthritis
• Other conditions: such as hepatitis, pancreatitis, AGN, and cardiac complication
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Stevens-Johnson-like syndrome
associated with Mycoplasma pneumoniae infection
DIAGNOSIS
PCR of a nasopharyngeal or throat swab for M. pneumoniae DNA carries a sensitivity
and a specificity of 80% to >97%.
Serologic tests (immunofluorescence tests or enzyme-linked immune assays) to
detect serum Ig M and IgG antibodies.
Cold hemagglutinins, but not specific.
Cultures on special media (SP4 agar media)
TREATMENT
• M. pneumoniae illness is usually mild, and most cases of pneumonia can be managed
without the need for hospitalization.
• Because mycoplasmas lack a cell wall, they inherently are resistant to β-lactam
agents that act by inhibiting the cell wall synthesis.
• M. pneumoniae is typically sensitive to macrolides (erythromycin, clarithromycin,
azithromycin).
• Macrolide-resistant strains
• > 8 yr, can use doxycycline.
• < 8 yr, quinolone tosufloxacin are approved in Japan for pediatric use to treat
macrolide-resistant M. pneumoniae infections
A.L.Y