Antibiotic Therapy



Antibiotic Therapy

DNI requires timely treatment with IV antibiotics at the time of diagnosis because of the rapidly progressive nature of these infections. Culture is not required before empiric antibiotic therapy; broad-spectrum coverage is usually mandatory, because most cases involve mixed flora of gram-positive cocci and gramnegative rods with or without anaerobes. As a result of increasing rates of MRSA in the community, especially in children younger than 2 years, clindamycin is the initial therapy of choice in this patient population. Antibiotic coverage may need to be expanded in cases of otologic or sinus infection or nosocomial infections, in which Pseudomonas is common, whereas expanded anaerobic coverage is often necessary for fulminate odontogenic infections.

Fluids obtained from aspiration or incision and drainage should be sent for culture and sensitivity because of the increasing rate of resistant organisms in the at-large community. Clindamycin resistance may be present in 5% to 10% of MRSArelated pediatric DNIs. Culture and sensitivity information is especially valuable in the setting of hospital-acquired infections or in an immunocompromised host. A detailed history and physical examination often identifies patients at risk for atypical infections, which should be confirmed by staining and culturing aspirated fluids or tissue biopsy samples.
Overall, both penicillin with or without metronidazole and clindamycin in the penicillin-allergic patient have proven to be effective in most cases. Ampicillin-sulbactam is recommended as a first-line drug given the up to 20% resistance rate to penicillin G and clindamycin in DNI. Penicillin resistance can be related to the synthesis of β-lactamase by streptococci, Prevotella, Porphyromonas, and Fusobacterium. The combined therapy of penicillin with metronidazole provides for broad coverage of both aerobic and anaerobic bacteria with the elimination of β -lactamase–producing bacteria and with minimal side effects. Eikenella corrodens is associated with some odontogenic infections and is resistant to clindamycin, metronidazole, and macrolides. Fluoroquinolones, specifically moxifloxacin, are recommended for treatment of E. corrodens. Moxifloxacin is effective against oral streptococci and anaerobes and can be taken orally with the same bioavailability as with the parenteral route; however, this drug should not be used in pregnant women or children because of its toxic effects on growing cartilage.
Third-generation cephalosporins, such as ceftriaxone, are able to cross the blood-brain barrier and are effective against oral streptococci and most oral anaerobes. Vancomycin can be used when all other previously discussed antibiotics are contraindicated. Its combined use with metronidazole is effective for gram-positive and obligate anaerobes. The choice of antibiotic therapy is typically dictated by the clinical scenario and the culture and sensitivity findings.
Prophylactic antibiotics before dental, oral, and head and neck procedures may reduce the risk of DNI. Prophylaxis should consist of an oral or IV dose of a β-lactamase–resistant penicillin or clindamycin given within 30 minutes of procedures on nonsterile body cavities; a first-generation cephalosporin (e.g., cephalexin) or clindamycin can be given for neck incisions in a sterile field. Prophylaxis is mandatory for any patient with a history of heart murmur or rheumatic valve disease and in those with vascular or joint prosthetic devices.
IV antibiotic therapy without surgical intervention may be sufficient in select circumstances. Several large series have shown resolution of DNI with antibiotic therapy alone in 60% of cases. If the patient is clinically stable and otherwise healthy with abscess cavities less than 2.5 cm in diameter and involving a single neck space, a 48- to 72-hour trial of empiric IV antibiotic therapy is appropriate. A trial of empiric antibiotics is recommended in almost all stable pediatric cases, becauseeven sizable collections may respond favorably to IV antibiotics
and steroids alone. In general, the patient should be kept on a nothing-by-mouth status and should be closely monitored for changes in clinical status and elevation in white blood cell count. Repeat imaging and/or surgical intervention are necessary in patients who fail to improve or who worsen during the observation period. If significant clinical improvement is noted with IV antibiotics after 48 to 72 hours, therapy is continued for 24 hours beyond normalization of symptoms, followed by a 2-week course of an equivalent oral antibiotic. Patients who require surgery usually need 48 to 72 hours of IV antibiotics postoperatively before discharge home on oral therapy.

Source: Cummings Otolaryngology, 6E (2015)

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