Treatment of Acute Bacterial Parotitis
For acute bacterial parotitis, initiate empiric antibiotic therapy targeting Staphylococcus aureus and anaerobes with nafcillin or oxacillin 1–2 g IV every 4–6 hours (or vancomycin 15–20 mg/kg IV every 8–12 hours if MRSA is suspected) plus metronidazole 500 mg IV every 8 hours, combined with aggressive hydration, sialogogues (lemon drops or sugar-free gum), warm compresses, and gland massage. 1, 2, 3
Microbiology and Pathogen-Directed Therapy
The most common pathogens in acute bacterial parotitis are Staphylococcus aureus (isolated in 53% of cases) and viridans streptococci (31% of cases), with anaerobes—including Fusobacterium nucleatum, Peptostreptococcus anaerobius, pigmented Prevotella and Porphyromonas species—playing a significant role, particularly in community-acquired infections. 1, 2, 3
Gram-negative organisms (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) are more frequently isolated in hospitalized or debilitated patients, while Streptococcus pneumoniae and Haemophilus influenzae are occasionally implicated. 1, 4
Anaerobic bacteria can be present in high concentrations (>10^6 CFU/mL) and may be the sole pathogens in some cases; therefore, empiric coverage must include anaerobic activity, and cultures should employ anaerobic techniques. 2
Empiric Antibiotic Regimens
First-Line Therapy (Community-Acquired, Immunocompetent Patients)
Nafcillin or oxacillin 1–2 g IV every 4–6 hours provides excellent coverage for methicillin-sensitive S. aureus (MSSA) and streptococci. 1, 3
Add metronidazole 500 mg IV every 8 hours to cover anaerobes, including Fusobacterium species and Peptostreptococcus species, which are frequently resistant to penicillin and erythromycin. 1, 2
Alternative combination: Ampicillin-sulbactam 3 g IV every 6 hours provides coverage for S. aureus, streptococci, and anaerobes in a single agent. 1
MRSA Coverage (Nosocomial Infection, Prior Antibiotic Exposure, or High Local MRSA Prevalence)
Vancomycin 15–20 mg/kg IV every 8–12 hours (target trough 15–20 mcg/mL) is the drug of choice for suspected or confirmed MRSA. 1, 3
Continue metronidazole 500 mg IV every 8 hours for anaerobic coverage when using vancomycin, as vancomycin lacks activity against anaerobes. 1, 2
Alternative: Linezolid 600 mg IV/PO every 12 hours covers MRSA and has some anaerobic activity, though metronidazole addition is still recommended for optimal anaerobic coverage. 1
Gram-Negative Coverage (Hospitalized, Immunocompromised, or Critically Ill Patients)
Piperacillin-tazobactam 4.5 g IV every 6 hours provides broad-spectrum coverage including Pseudomonas aeruginosa, E. coli, Klebsiella species, S. aureus (MSSA), and anaerobes. 1, 4
For MRSA risk in this population, add vancomycin 15–20 mg/kg IV every 8–12 hours to piperacillin-tazobactam. 1, 3
Culture-Directed Therapy Adjustments
Obtain purulent material via needle aspiration of the gland or from Stensen's duct for Gram stain, aerobic and anaerobic culture, and antibiotic susceptibility testing before initiating antibiotics whenever possible. 1, 2, 3
If S. aureus is isolated and susceptible to nafcillin/oxacillin (MSSA), narrow therapy to nafcillin or oxacillin 1–2 g IV every 4–6 hours and discontinue vancomycin. 3
If MRSA is confirmed, continue vancomycin 15–20 mg/kg IV every 8–12 hours (target trough 15–20 mcg/mL) for the full treatment course. 3
If anaerobes are isolated (especially Fusobacterium species), ensure metronidazole 500 mg IV every 8 hours is continued, as these organisms may be resistant to penicillin, amoxicillin, and erythromycin. 2
If gram-negative organisms (E. coli, Klebsiella, Pseudomonas) are isolated, tailor therapy based on susceptibilities; piperacillin-tazobactam or a third-generation cephalosporin (ceftriaxone 1–2 g IV daily) plus metronidazole are appropriate. 1, 4
Essential Adjunctive Measures
Aggressive IV hydration (at least 2–3 liters/day in adults) is critical to restore salivary flow and flush bacteria from the ductal system. 1, 4, 3
Sialogogues—lemon drops, sugar-free gum, or lemon juice—stimulate saliva production and mechanically clear the duct; instruct patients to use these every 2–3 hours while awake. 1, 4
Warm compresses applied to the affected gland for 15–20 minutes four times daily, combined with gentle gland massage from posterior to anterior, promote drainage and reduce swelling. 1, 4
Maintain meticulous oral hygiene with chlorhexidine mouthwash 0.12% twice daily to reduce oral bacterial load and prevent ascending infection. 1, 4
Analgesics (acetaminophen 650–1000 mg PO every 6 hours or ibuprofen 400–600 mg PO every 6–8 hours) and anti-inflammatory agents provide symptomatic relief. 5
Indications for Surgical Drainage
Surgical incision and drainage is required when an abscess has formed, indicated by fluctuance on examination, persistent fever despite 48–72 hours of appropriate antibiotics, or imaging (ultrasound or CT) demonstrating a fluid collection. 1, 5, 4
Drainage should be performed urgently if there is rapid progression, airway compromise, or extension to adjacent spaces (e.g., retroauricular abscess, parapharyngeal space involvement). 5, 4
Percutaneous needle aspiration may be attempted for small abscesses (<3 cm), but formal surgical drainage is preferred for larger collections or when needle aspiration fails. 1, 5
Treatment Duration and Monitoring
Continue IV antibiotics until the patient is afebrile for 24–48 hours, has significant clinical improvement (reduced swelling, pain, and purulent discharge), and can tolerate oral intake. 5, 3
Transition to oral antibiotics to complete a total course of 10–14 days: dicloxacillin 500 mg PO four times daily (for MSSA) or trimethoprim-sulfamethoxazole 1–2 double-strength tablets PO twice daily (for MRSA) plus metronidazole 500 mg PO three times daily (for anaerobes). 1, 3
Reassess at 48–72 hours of IV therapy; lack of improvement should prompt imaging (ultrasound or CT) to evaluate for abscess formation, ductal obstruction (sialolithiasis), or alternative diagnoses. 5, 4, 3
Criteria for Hospitalization
Hospitalize patients with any of the following: inability to maintain oral hydration, severe systemic toxicity (high fever >39°C, tachycardia, hypotension), immunocompromised state (diabetes, HIV, chemotherapy, chronic corticosteroid use), suspected abscess formation, or failure of outpatient oral antibiotic therapy. 5, 4, 3
Elderly or debilitated patients with acute bacterial parotitis should be hospitalized for IV antibiotics and hydration, as they are at higher risk for complications and nosocomial infection. 4, 3
Prevention and Risk Factor Modification
Maintain adequate hydration (at least 2 liters/day orally in ambulatory patients) to ensure continuous salivary flow and prevent ductal stasis. 1, 4
Optimize oral hygiene with regular tooth brushing, flossing, and chlorhexidine mouthwash to reduce oral bacterial colonization. 1, 4
Avoid anticholinergic medications (antihistamines, tricyclic antidepressants, antipsychotics) that reduce salivary flow and predispose to infection. 4
Promptly treat oropharyngeal bacterial infections (pharyngitis, dental abscesses) to prevent ascending infection via Stensen's duct. 1, 4
Common Pitfalls to Avoid
Do not rely solely on penicillin or amoxicillin for empiric therapy, as many anaerobes (especially Fusobacterium species) and S. aureus are resistant; always include anti-staphylococcal and anti-anaerobic coverage. 1, 2
Do not assume all cases are due to S. aureus; anaerobes may be the sole pathogens in up to 30% of cases, and failure to cover anaerobes leads to treatment failure. 2, 3
Do not delay surgical drainage when an abscess is present; antibiotics alone will not resolve a walled-off collection, and delayed drainage increases morbidity. 1, 5, 4
Do not overlook the need for anaerobic culture techniques; standard aerobic cultures will miss anaerobes, leading to inappropriate antibiotic selection. 2
Do not discharge patients on oral antibiotics without ensuring adequate hydration and sialogogue use, as these adjunctive measures are essential for treatment success. 1, 4