Antibiotic Recommendations

Published on 10/02/2015 by admin

Filed under Emergency Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1191 times

185 Antibiotic Recommendations

Ellen M. Slaven

The proper selection of antibiotic therapy in the setting of the emergency department (ED) is often complicated. The offending pathogen is rarely known with certainty, and emergency physicians must contend with diseases caused by emerging microbes, such as human immunodeficiency virus and the coronavirus that causes sudden acute respiratory syndrome. Many common bacterial pathogens have developed novel antimicrobial resistance patterns, such as drug-resistant Streptococcus pneumoniae and Escherichia coli, and some well-known bacteria have developed new strains, such as community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Complicating this challenge is a perpetually growing list of new antimicrobial agents, and emergency physicians clearly must remain diligent to keep current with the ever-changing arena of infectious diseases that are frequently encountered in the ED.

Fortunately, many helpful resources are available, such as local hospital antibiograms and hospital-specific protocols. National guidelines such as the Surviving Sepsis Campaign and the Centers for Disease Control and Prevention (CDC) guidelines for sexually transmitted diseases provide helpful references. The annually updated Sanford Guide to Antimicrobial Therapy remains an invaluable up-to-date tool literally found within one’s pocket.

In general, antibiotic therapy is empiric, based on epidemiologic data of the most likely encountered pathogen. Critically ill patients benefit from early and appropriate antibiotic therapy and therefore initially require broad-spectrum therapy, unless a specific pathogen has been identified. Whenever possible, the safest, least expensive, and easiest to administer antibiotic should be prescribed. Oral therapy is preferable over parenteral, and single-dose regimens eliminate concerns regarding compliance when compared with multidose regimens.

Recommendations for antibiotic therapy in the ED for selected infectious diseases are outlined in the sections that follow.

Odontogenic Infections

Penicillin (Pen Vee K, 500 mg orally [PO] four times daily for 5 to 7 days) is indicated for dentoalveolar abscesses, such as periapical abscesses. Clindamycin (300 mg PO four times daily for 5 to 7 days) is an alternative for penicillin-allergic patients. Significant abscesses (i.e., those causing facial swelling) require emergency drainage in addition to antibiotics. For patients admitted to the hospital with severe infection, ampicillin-sulbactam (1.5 g intravenously [IV] every 6 hours) is preferred. Clindamycin (900 mg IV every 6 hours) is again a suitable alternative.

Pharyngitis

Penicillin (Pen Vee K, 500 mg PO four times daily for 10 days) remains the drug of choice for group A streptococcal pharyngitis. A single intramuscular injection of benzathine penicillin (600,000 units if the patient’s weight is < 27 kg and 1.2 million units if it is >27 kg) may be administered to enhance compliance.

Patients with allergy to penicillin may be treated with azithromycin (500 mg PO on day 1, then 250 mg PO every day for 4 days). Group A Streptococcus has not developed resistance to penicillin, but approximately one third of isolates are resistant to macrolides or clindamycin. Linezolid (400 mg PO twice daily for 10 days) may be used for resistant strains.

Acute Sinusitis

Mild symptoms of acute sinusitis may initially be treated with decongestants and analgesics. Reserve antibiotics for those in whom such conservative therapy fails and in patients with more severe symptoms, such as severe maxillary or facial pain and fever. High-dose amoxicillin is the preferred agent (adults: 1 g PO three times daily for 10 days; children: 90 mg/kg/day PO divided three times daily for 10 days).

Otitis Externa

Hydrocortisone, polymyxin B, and neomycin combined (Cortisporin otic, 4 drops in affected ear four times daily for 7 days) remain the standard therapy for otitis externa. If the tympanic membrane is perforated, a preferred combination of ciprofloxacin with hydrocortisone (3 drops in affected ear twice daily for 7 days) is indicated because of the ototoxicity of neomycin. Removal of debris from the ear canal promotes enhanced entry of the medication deep into the canal. When the canal is sufficiently swollen, a wick may need to be carefully placed to allow medication penetration.

Otitis Media

A prudent approach is to withhold antibiotics for 48 hours in afebrile children with otitis media who are more than 2 years old and are without pain. Treat with high-dose amoxicillin for 7 days (adults: 1 g PO three times daily; children: 90 mg/kg/day PO divided three times daily). Alternative therapy is with azithromycin (adults: 500 mg PO on day 1, then 250 mg PO every day for 4 days; children: 10 mg/kg [maximum, 500 mg] PO on day 1, then 5 mg/kg [maximum, 250 mg] PO every day for 4 days).

Acute Bacterial Meningitis

The treatment of acute bacterial meningitis is guided by epidemiologic risk factors; likely pathogens are determined primarily by the age of the patient and by exposure following trauma or surgical intervention. The goal of treatment is to administer antibiotics within 30 minutes of the patient’s arrival to the ED.

A Cochrane Review of more than 4000 patients with acute bacterial meningitis concluded that the use of adjunctive steroids decreases neurologic sequelae including hearing loss. Dexamethasone should be given intravenously 15 minutes before or concomitantly with the first dose of antibiotics and continued for 4 days (adults: 10 mg every 6 hours; children: 0.15 mg/kg every 6 hours).

Neonates (<1 month old): Combination treatment with ampicillin (200 mg/kg/day IV divided every 6 hours) and cefotaxime (300 mg/kg/day IV divided every 6 hours) targets the most common pathogens, which are group B Streptococcus, E. coli, and Listeria species.

Age 1 month to 50 years: Ceftriaxone (adults: 2 g IV every 12 hours; children: 100 mg/kg/day [maximum, 2 g] IV divided every 12 hours) with vancomycin (adults: 15-20 mg/kg [maximum, 2 g] IV every 12 hours; children: 15 mg/kg [maximum, 2 g] IV every 6 hours) provides coverage against S. pneumoniae (including penicillin-resistant strains), Neisseria meningitidis, and Haemophilus influenzae (although now rare because of the Hib vaccine).

Age greater than 50 years: Ampicillin (2 g IV every 4 hours), ceftriaxone (2 g IV every 12 hours), and vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) are combined to cover S. pneumoniae, Listeria species, and gram-negative bacilli.

Postoperative/trauma: S. pneumoniae, S. aureus (including MRSA), and gram-negative bacilli (including Pseudomonas aeruginosa) are common pathogens in this setting; thus, ceftazidime (2 g IV every 8 hours) combined with vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) is recommended.

Community-Acquired Pneumonia

Both the Infectious Diseases Society of American and the American Thoracic Society provide guidelines for the management of community-acquired pneumonia. For outpatient management of otherwise healthy patients, azithromycin (500 mg PO on day 1, then 250 mg PO every day for 4 days) or doxycycline for 7 to 10 days (age > 8 years: 100 mg PO twice daily for 7 days) remains an excellent option.

If the patient has comorbid illness, then a respiratory fluoroquinolone (with enhanced activity against S. pneumoniae) is indicated, such as levofloxacin (750 mg PO every day), moxifloxacin (400 mg PO every day), or gemifloxacin (320 mg PO every day). Telithromycin is not recommended here out of concern for hepatotoxicity.

For inpatients, combination therapy is recommended for with ceftriaxone (2 g IV every 24 hours) and azithromycin (500 mg IV every 24 hours). Alternatives include intravenous respiratory fluoroquinolones levofloxacin (750 mg IV every day) or moxifloxacin (400 mg IV every day).

Patients admitted to the intensive care unit should be treated with either levofloxacin (750 mg IV every day) or moxifloxacin (400 mg IV every day), with the addition of either vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) or linezolid (600 mg IV every 12 hours) if MRSA is suspected (i.e., after influenza, severe disease with hemoptysis, and necrotizing features). If the patient has a life-threatening illness or suspicion of P. aeruginosa (i.e., an alcoholic patient, or one with underlying bronchiectasis or malignant disease), also add piperacillin-tazobactam (4.5 g IV every 6 hours) or aztreonam (2 g IV every 6 hours).

Pediatric Patients

Neonates with pneumonia require treatment for group B Streptococcus, Listeria species, and gram-negative bacilli. The combination of ampicillin (50 mg/kg IV every 12 hours) and gentamicin (2.5 mg/kg IV first dose) is recommended.

Children treated as outpatients require coverage for S. pneumoniae, and high-dose amoxicillin (100 mg/kg divided every 8 hours) is commonly used. An alternative is azithromycin (10 mg/kg [maximum, 500 mg] PO on day 1, then 5 mg/kg [maximum, 250 mg] PO every day for 4 days). If the patient is hospitalized, then use ceftriaxone (50 mg/kg IV every day) for children younger than 5 years. Add azithromycin (10 mg/kg [maximum, 500 mg] divided IV every 12 hours) if children are older than 5 years. For severe infection, add vancomycin (15 mg/kg IV every 6 hours).

Cholecystitis

Enterobacteriaceae such as E. coli and Proteus species are the most common pathogens in cholecystitis, as well as other biliary tract infections, and antibiotic selection must take into consideration adequate activity against these gram-negative bacilli. Other pathogens include anaerobes and enterococci. A regimen of piperacillin-tazobactam (3.375 g IV every 6 hours) alone or ciprofloxacin (500 mg IV every 12 hours) with metronidazole (1 g IV first dose) is recommended, in addition to surgical intervention.

Diarrhea (Dysentery)

Mild to moderate diarrhea is best managed with antimotility agents and fluids. Severe diarrhea (i.e., more than six unformed stools/day, the presence of fever, or bloody stools) is an indication for antimicrobial therapy. Fluoroquinolones, either ciprofloxacin (500 mg PO twice daily) or levofloxacin (500 mg PO every day), remain the drugs of choice. Trimethoprim-sulfamethoxazole ([TMP-SMX] 1 double-strength [DS] tablet PO twice daily) is an alternative. All regimens are recommended for 3 to 5 days. If the patient has recently received antibiotic therapy and Clostridium difficile colitis is considered, then add metronidazole (500 mg PO three times daily) for 10 to 14 days.

Urinary Tract Infection

Growing concern exists about widespread and increasing resistance of E. coli to TMP-SMX and ciprofloxacin. In 2009, the rate of resistance to each of these two agents was greater than 25% in many regions of the United States. Knowledge of local antibiotic resistance patterns in urinary pathogens may assist in the empiric treatment of urinary tract infections. TMP-SMX (1 DS tablet PO twice daily for 3 days) is the drug of choice if the local rate of resistance to TMP-SMX is less than 20%. Ciprofloxacin (250 mg PO twice daily for 3 days) or levofloxacin (250 mg PO every day for 3 days) is an alternative if the local rate of resistance to fluoroquinolones is less than 20%. (Moxifloxacin and gemifloxacin have low urinary concentrations and are not recommended.) An alternative for uncomplicated urinary tract infections is nitrofurantoin (100 mg PO four times daily for 7 days) or fosfomycin (3 mg PO once).

Pyelonephritis is initially treated with ciprofloxacin (500 mg PO twice daily for 7 days) or levofloxacin (250 mg PO every day for 7 days). Hospitalized patients may receive ciprofloxacin IV (400 mg twice daily) or levofloxacin (750 mg every day) for 14 days. Urinary cultures must be obtained to assess for possible resistance to fluoroquinolones. An alternative regimen is ampicillin (2 g IV every 6 hours) plus gentamicin (5 mg/kg IV every 24 hours), or piperacillin-tazobactam alone (3 g IV every 6 hours) for 14 days.

Sepsis

Patients with sepsis who do not have a clear source of infections require early broad-spectrum antibiotics; the goal is intravenous antibiotic administration within the first hour of their presentation to the ED. Imipenem (500 mg IV every 6 hours) plus vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) or piperacillin-tazobactam (4.5 mg IV every 6 hours) with vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) is recommended. In penicillin-allergic patients, a combination of ciprofloxacin (400 mg IV every 12 hours), metronidazole (1 g IV every 12 hours), and vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) may be prescribed.

Neonatal sepsis (<1 month of age) may be empirically treated with ampicillin (25 mg/kg IV every 8 hours) and cefotaxime (50 mg/kg IV every 12 hours). Vancomycin (15 mg/kg IV every 12 hours) should be added if MRSA is a potential concern.

Empiric therapy of childhood sepsis is with ceftriaxone (100 mg/kg in every 24 hours) plus vancomycin (15 mg/kg [maximum dose, 2 g] IV every 12 hours).

Cellulitis

A newer paradigm has been proposed by the Infectious Diseases Society of America for the treatment of cellulitis in the era of CA-MRSA. This protocol is based on the detection of purulent material associated with cellulitis and the likely presence of CA-MRSA.

Dry cellulitis, or cellulitis not associated with exudates, purulence, or abscess formation, is likely caused by β-hemolytic streptococci, such as Streptococcus pyogenes, and should be treated with an antibiotic targeting these organisms; that is, cephalexin (500 mg PO four times daily) or dicloxacillin (500 mg PO four times daily) for 5 to 10 days. The precise duration of therapy should be dictated by the clinical response.

Cellulitis associated with an underlying abscess or with purulent exudates must be treated with an agent that is active against CA-MRSA, such as TMP-SMX (1 DS tablet PO twice daily), clindamycin (300 mg PO four times daily) or doxycycline (100 mg PO twice daily) for 5 to 10 days. Vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours) remains the drug of choice for patients requiring hospitalization. Clindamycin (900 mg IV every 8 hours) is an alternative. Linezolid (600 mg IV every 12 hours) is not recommended as first-line therapy, primarily because of its higher cost.

Skin and soft tissue infections that are limb- or life-threatening should be treated empirically with imipenem (500 mg IV every 6 hours) and vancomycin (15 to 20 mg/kg [maximum, 2 g] IV every 12 hours).

Mammalian Bites

Prophylaxis against infection following the bite of an animal must provide coverage against Pasteurella species, S. aureus, and anaerobes. Amoxicillin-clavulanate (875/125 mg PO twice daily) is the primary oral agent and should be prescribed for 3 days. Dual therapy with clindamycin (300 mg PO four times daily) plus ciprofloxacin (500 mg PO twice daily), also for 3 days, is an alternative regimen for patients with penicillin allergy.

Outpatient treatment of an established soft tissue infection resulting from an animal bite may be implemented with the same antibiotics used for prophylaxis, only for a longer duration (i.e., 7 to 10 days). Patients hospitalized with severe infection may be treated with one of the β-lactam–β-lactamase inhibitors (ampicillin-sulbactam, 1.5 g IV every 6 hours, or piperacillin-tazobactam, 3.375 g IV every 6 hours). Alternatively, clindamycin (900 mg IV every 8 hours) with a fluoroquinolone (ciprofloxacin, 400 mg IV every 12 hours, or levofloxacin, 500 mg IV every 24 hours) may be given.

Sexually Transmitted Diseases

Urethritis and Cervicitis

Dual therapy with ceftriaxone (250 mg intramuscularly [IM] once) for coverage of penicillin and fluoroquinolone-resistant Neisseria gonorrhoeae and azithromycin (1 g PO) for Chlamydia trachomatis is recommended. The more recently recognized Mycoplasma genitalium is also covered by azithromycin. For patients with severe penicillin allergy, 2 g of azithromycin PO may be given.

Syphilis

The treatment of syphilis has remained essentially unchanged since the 1940s, when penicillin was introduced. Today, penicillin remains the drug of choice for syphilis.

For primary, secondary, and early latent (<1 year) syphilis, a single injection of benzathine penicillin G (2.4 million units IM) is recommended. Patients with severe penicillin allergy may be treated with doxycycline (100 mg PO twice daily) for 14 days.

Late latent syphilis, syphilis of unknown duration, and tertiary syphilis are treated with three injections, 1 week apart, of benzathine penicillin G (2.4 million units IM). Doxycycline (100 mg PO twice daily) for 4 weeks is an alternative.

Neurosyphilis requires intravenous administration of aqueous crystalline penicillin G (4 million units every 4 hours for 10 to 14 days).

Chanchroid

Fortunately, the painful genital ulcers of chancroid, caused by the difficult to detect Haemophilus ducreyi, have declined in prevalence in the United States. Single-dose therapy is recommended with azithromycin (1 g PO) or ceftriaxone (250 mg IM).

Epididymitis and Prostatitis

Men 35 years of age and younger who have either epididymitis or prostatitis must be treated with antimicrobial agents that target the sexually transmitted pathogens N. gonorrhoeae and C. trachomatis with ceftriaxone (250 mg IM once) and doxycycline (100 mg PO twice daily for 10 days). In contrast, men older than 35 years are more likely to be infected with Enterobacteriaceae, and fluoroquinolones are recommended; that is, ciprofloxacin (500 mg PO twice daily) or levofloxacin (750 mg PO every day) for 10 to 14 days.

Suggested Readings

Brouwer MC, McIntyre P, de Gans J, et al. Corticosteroids for bacterial meningitis. Cochrane Database Syst Rev. (9):2010. CD004405

Centers for Disease Control and Prevention. Sexually transmitted diseases: treatment guidelines, 2010. MMWR Morb Mortal Wkly Rep. 2010;59:1–109.

Gilbert DN, Moellering RC, Eliopoulous GM, et al. The Sanford guide to antimicrobial therapy, 40th ed. Sperryville, Va: Antimicrobial Therapy; 2010.

Liu C, Bayer A, Cosgrove S, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children: executive summary. Clin Infect Dis. 2011;52:285–292.

Mandell LA, Bartlett JG, Dowell SF, et al. Update of practice guidelines for the management of community-acquired pneumonia in immunocompetent adults. Clin Infect Dis. 2003;37:1405–1433.

Niederman MS, Mandell LA, Anzueto A, et al. Guidelines for the management of adults with community-acquired pneumonia: diagnosis, assessment of severity, antimicrobial therapy, and prevention. Am J Respir Crit Care Med. 2001;163:1730–1754.

Related posts:

Pediatric Abdominal Disorders Fluid Management Introduction to Cost-Effectiveness Analysis Altered Mental Status and Coma Vasculitis Syndromes Pericarditis, Pericardial Tamponade, and Myocarditis