Respiratory Infections and Mononucleosis: Diagnosis and Treatment
Respiratory Infections: A Comprehensive Overview
Upper Respiratory Tract Infections
Pharyngoamigdalitis
Most cases are viral, so antibiotics should only be administered when the patient has a fever > 38°C, exudate, anterior cervical lymphadenopathy, and absence of cough. The preferred treatment is Amoxicillin 500mg/8h for 10 days.
Rhinitis
Most cases are mucopurulent and viral. Antibiotics are only indicated when symptoms persist for more than 7 days, often involving sinus involvement.
Sinusitis
Common causes include Streptococcus pneumoniae, Haemophilus influenzae, and viruses. Clinical presentation includes frontal headache, purulent secretion, and fever. Treatment involves Amoxicillin-clavulanate for 10-14 days or macrolides (clarithromycin, azithromycin).
Acute Otitis Media
Similar etiology to sinusitis. Symptoms include pain, redness, bulging eardrum, and secretion. Treatment involves Amoxicillin-clavulanate + macrolide or NSAIDs.
Lower Respiratory Tract Infections
Acute Bronchitis
Generally viral. Symptoms include cough, drainage, fever, and crackles. Treatment includes NSAIDs + cough suppressants. If bronchospasm is present, bronchodilators may be used. Antibiotics are only indicated in cases of purulent sputum or signs of severity.
Community-Acquired Pneumonia
Most frequently caused by Streptococcus pneumoniae and Mycoplasma pneumoniae. Empirical treatment includes amoxicillin 1g/8h, procaine penicillin 1,200,000 U/12h, or erythromycin 500mg/6h for up to 14 days.
Suspect resistant pneumococcus in cases of: nosocomial pneumonia acquisition, hospitalization within the previous 3 months, pneumonia in the previous year, underlying disease, or living with children under 5 years. Treatment for resistant cases includes Levofloxacin 500 mg/24h or Moxifloxacin 400 mg/24h for 5-10 days. Telithromycin (a ketolide) can be used at 800 mg/24h, but not in patients under 12 years.
Mortality from pneumonia increases with: age, associated diseases, polylobulated involvement, leukocytosis > 30,000 or leukopenia < 400, hypotension.
Mononucleosis Syndrome
Etiology: Diverse, with EBV being the most frequent cause (90%). Other causes include CMV (10%), Toxoplasma, human herpesvirus 6, HIV, rubella, listeria, chickenpox, adenovirus, brucellosis, mumps, syphilis, Q fever, herpes, etc.
Clinical Triad:
- Fever (10-14 days, high and persistent)
- Lymphadenopathy (posterior cervical, occipital, or retroauricular, inflammatory and painful on palpation)
- Sore throat (erythematous pharynx with pultaceous, gray exudate, very painful)
Analytical Characteristics: CBC shows leukocytosis with > 50% mononuclear cells (lymphocytes) in peripheral blood and a % of atypical lymphocytes > 10%. Neutropenia and altered liver tests are also common.
Incubation Period: 4-6 weeks.
Epidemiology (EBV): A highly prevalent herpes virus (95% of adults have antibodies against it). It persists in the oropharynx for up to 18 months after the disease, making asymptomatic individuals potential transmitters. It usually affects young adults (15 to 25 years old), upper-middle class, and individuals in developed countries. The method of infection is saliva (“kissing disease”).
Diagnosis: Paul-Bunnel test (detection of heterophil antibodies; a titer greater than 1:56 is considered positive). 10% of patients may be negative. Serological tests can detect 3 types of antibodies: anti-VCA (against viral capsid Ag), anti-EBNA (nuclear versus Ag), and anti-EA (early versus Ag).
Evolution: The majority of cases resolve spontaneously in 2-3 weeks. Rarely, it evolves torpidly, causing asthenia or a progressive infection with multiorgan involvement.
Complications: Death from splenic rupture, meningitis, encephalitis, or upper airway obstruction.
Treatment: Usually symptomatic: Paracetamol or NSAIDs, abundant fluid intake, and relative rest. Corticosteroids may be used in case of complications.
Rash by aminopenicillins: If this syndrome is suspected and penicillin is administered for strep throat, the patient may develop a rash.
Other Causes:
- CMV: Prolonged fever + less marked lymphadenopathy, affects a slightly older age group (25-35 years old), transmission via blood or sexual contact, serological diagnosis.
- Toxoplasmosis: Fever and lymphadenopathy, no pharyngitis.