Case Files 2: I'm Hot, and Coughing My Ears Out (Answers)

Answers:

1. C: White blood cells without organisms
The sign and symptoms of the patient are rather patchy, thus nothing much can be obtained apart from a possible cold or pneumonia.

The sign of inflamed tympanic membrane with bullous lesion(s) is known as bullous myringitis. Bullous myringitis is suggestive of infective organisms such as strep. pneumoniae, mycoplasma pneumoniae, and viral infections including herpes zoster, influenza and others.

However, the sign of bullous myringitis coupled with lower zone pneumonia are suggestive of strep. pneumoniae or mycoplasma pneumoniae. The high level of lymphocytes would rule out the latter as strep pneumoniae induces an increase in neutrophils instead. (WBC count are generally unhelpful in mycoplasma pneumoniae though, so this can't be ruled out)

Therefore, the sputum Gram Stain will most likely yield nothing of interest apart from the possible normal oral flora of peptostreptococci, since mycoplasma's cell wall can't be stained. Also, there would be presence of leucocytes as a result of the rise in lymphocytes. The best answer would be C, as there are no gram postive cocci chains(peptostreptococci) stated in the choices. Gram positive diplococci are characteristic of streptococcus pneumoniae.

2. B: High titers of IgM cold agglutinins

Serum cold agglutination is a nonspecific test for M pneumoniae, but findings are positive in 50-70% of patients after 7-10 days of infection. Therefore, the answer for 2 would be B.

WBC count is generally unhelpful as it may be raised or normal. Sputum Gram Stain is also unhelpful, as discussed earlier. ESR may be present but non-specific, thus serology tests are usually required.

M pneumoniae is difficult to culture and requires 7-21 days to grow; culturing is successful in only 40-90% of cases and does not provide information to guide patient management. Others include complement fixation, enzyme-linked immunoassay, and indirect hemagglutination may be prove useful in diagnostic with acceptable sensitivity and specificity.

Polymerase chain reaction (PCR) has been shown to accurately diagnose atypical pneumonia and has been used for epidemiologic studies, but it is currently not used in most clinical settings. Only a few places employ PCR as the diagnostic test.

3. A: Erythromycin

The treatment of choice would have to be erythromycin for M. pneumoniae. And the dosage recommended are:

Adult: 500 mg PO qid for 7-10 d
Pediatric: 7.5-12.5 mg/kg/dose PO qid for 7-10 d

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting. In the treatment of mycoplasmal pneumonia, antimicrobials against M pneumoniae are bacteriostatic, not bactericidal.

Common side effects are hypersensitivity and hepatic impairment. GI adverse effects are common. If nausea, vomiting, malaise, abdominal colic, or fever occur, treatment should be stopped immediately.

4. Further Management and Complications

Emergency Department Care:
Mycoplasmal pneumonia should be considered as a possible etiology in any emergency department patient presenting with 3 weeks of a steadily progressive cough. Patients are usually not critically ill, but seek relief from the persistent, worsening cough. Occasionally, various pulmonary and extrapulmonary complications may occur and may require emergent attention.

Outpatient Care:
Antibiotic prophylaxis for exposed contacts is not routinely recommended. However, macrolide or doxycycline prophylaxis should be used in households in which patients with underlying conditions may be predisposed to severe mycoplasmal infection, such as those with sickle cell disease or antibody deficiencies.

Complications include:

• Lobar consolidation
• Abscess
• Bronchiolitis obliterans
• Necrotizing pneumonitis (FAQ: What are the other microorganisms causing this?)
  
• Acute respiratory distress syndrome
• Respiratory failure
• Extremely rare extrapulmonary complications include the following: myocarditis, pericarditis, conduction abnormalities, encephalitis, Guillain-Barré syndrome, peripheral neuropathy, transverse myelitis, hemolytic anemia, coagulopathies, erythema multiforme, macular exanthems, vesicular exanthems, erythema nodosum, and urticaria.

5. General investigations done for patients with suspected pneumonia, and its indications

1. Complete Blood Count for WCC count - infection ( WCC count may be normal in elderly)
2. C-Reactive Protein - usually >100 in pneumonia
3. Renal Profile - impairment in severe infection
4. Liver Function Test - Legionella may cause abnormal liver profile
5. Chest X- Ray - looking for consolidation, pulmonary embolism, cardiomegaly, etc.
6. Blood Culture and Sensitivity - microorganism
   
7. Sputum Gram Stain, Culture and Sensitivity, AFB(3X) and FEME -microorganisms
   
8. Urinalysis - checking for Legionella or pneumococcal antigen.

Further Investigations if required includes:

• ABG - if respiratory failure with [O2] therapy given as well
  
• Serology - for severe pneumonia, unresponsive to B-lactam antibiotics
  
  • usually M. pneumoniae, chlamydia spp., influenza A or B, adenoviruses, RSV, Legionella pneumophilia.

Source:

• E-medicine
• Med Case Reports