More antibiotics are prescribed for treatment of acute otitis media (AOM) than for any other infection in young children. Children with AOM typically present with otalgia, fever, and bulging and erythema of the tympanic membrane.

Treatment of community-acquired pneumonia (CAP) is usually empiric, with selected antibiotic regimens directed against some of the most common causative pathogens. Recommended empiric regimens are listed in Table 2; recommended antibiotic dosages for treatment of CAP are listed in Tables 3 and 4. Joint guidelines for treatment of CAP by the American Thoracic Society and the Infectious Diseases Society of America (ATS/IDSA) were updated in 2019.

The main goals of treatment for chronic obstructive pulmonary disease (COPD) are to relieve symptoms, reduce the frequency and severity of exacerbations, and prevent disease progression. Several guidelines and review articles on COPD treatment have been published in recent years. Treatment of acute exacerbations is not discussed here.

The severity and rapid spread of COVID-19 (caused by SARS-CoV-2) have raised questions about the use of some drugs in patients with the disease and whether currently available drugs could be effective in treating it. Definitive answers are lacking, but some recommendations can be made. For additional information on specific drugs, see our table Some Drugs Being Considered for Treatment of COVID-19.

View the Table: Treatments Considered for COVID-19

The severity and rapid spread of COVID-19 (caused by SARS-CoV-2) have raised questions about the use of some drugs in patients with the disease and whether currently available drugs could be effective in treating it. Definitive answers are lacking, but some recommendations can be made. For additional information on specific drugs, see our table Some Drugs Being Considered for Treatment of COVID-19.

Patients who receive pretravel advice can reduce their risk for many travel-related conditions. Vaccines recommended for travelers are reviewed in a separate issue.

View the Expanded Table: Antibiotics for Travelers' Diarrhea

The FDA has approved rifamycin (Aemcolo – Cosmo/ Aries), a minimally absorbed oral antibiotic, for treatment of adults with travelers' diarrhea (TD) caused by noninvasive strains of Escherichia coli. It is not recommended for treatment of diarrhea that is complicated by fever and/or bloody stools. Topical and injectable formulations of rifamycin have been used in Europe for other indications for many years.

Bacterial infections in adults are generally treated empirically, with the antibiotic covering most, but not all, of the potential causative pathogens. For some infections, culture and sensitivity testing can guide treatment, allowing for use of narrower-spectrum antibiotics. The recommended dosages and durations of antibiotic treatment for common respiratory, skin, and urinary tract infections are listed in Tables 1-3. Infectious disease experts now recommend shorter treatment durations for many infections to reduce the development of antimicrobial resistance and minimize adverse effects.

The text and tables that follow include recommendations for management of sexually transmitted infections (STIs) other than HIV and viral hepatitis. Some of the indications and dosages recommended here have not been approved by the FDA.

The main goals of treatment for chronic obstructive pulmonary disease (COPD) are to relieve symptoms, reduce the frequency and severity of exacerbations, and prevent disease progression. Updated guidelines for treatment of COPD have been published in recent years.

Patients planning to travel to other countries often ask for information about prevention of diarrhea, malaria, and other travel-related conditions. Vaccines recommended for travelers based on their destination, length of stay, and planned activities were reviewed in a previous issue.

Many infections can be transmitted during sexual contact. The text and tables that follow include recommendations for management of sexually transmitted infections (STIs) other than HIV, viral hepatitis, and enteric infections. Some of the indications and dosages recommended here have not been approved by the FDA.

The text that follows reviews some common bacterial infections and their empiric treatment pending the results of culture and susceptibility testing. The recommendations made here are based on the results of susceptibility studies, clinical trials, and the opinions of Medical Letter reviewers. Tables 1 and 2 list the usual dosages of antibacterial drugs.

The FDA has announced that it is requiring changes in the labeling of the macrolide antibiotic azithromycin (Zithromax, Zmax) to warn about the risk of QT prolongation and cardiac arrhythmias.1 The new warnings are based on a retrospective study in The New England Journal of Medicine (reviewed previously in The Medical Letter2), which found that among patients who received 347,795 prescriptions for azithromycin, there were 29 cardiovascular deaths, a significantly higher rate than the 42 that occurred among patients who received 1,348,672 prescriptions for amoxicillin (which does not prolong the QT interval) or the 41 that occurred among 1,391,180 patients who took no antibiotics. The risk with azithromycin was much higher in patients with cardiovascular risk factors.3

Other macrolides and fluoroquinolones can also prolong the QT interval. In the retrospective study, the risk of cardiovascular death with levofloxacin was not significantly different from the risk with azithromycin. As with any retrospective study, the possibility that baseline differences between patients taking azithromycin and those taking other or no antimicrobials could have been responsible for the difference in cardiovascular outcomes cannot be entirely ruled out.

1. FDA Drug Safety Communication: Azithromycin (Zithromax or Zmax) and the risk of potentially fatal heart rhythms. Available at www.fda.gov/drugs/drugsafety/ucm341822.htm. Accessed March 14, 2013.

2. In brief: safety of azithromycin. Med Lett Drugs Ther 2012; 54:45.

3. WA Ray et al. Azithromycin and the risk of cardiovascular death. N Engl J Med 2012; 366:1881.

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The CDC has reported that many states are experiencing a higher-than-usual incidence of pertussis this year. The highest incidence has been in infants, but the disease has also occurred in older children, adolescents, and adults. Thirteen pertussis-related deaths were reported through August 24; the majority of these were in infants <3 months old.

Since 2007, antimicrobial prophylaxis for dental procedures has been recommended only for patients at highest risk of severe consequences from infective endocarditis. There is no indication that more limited use of dental prophylaxis since then has led to an increase in the incidence of infective endocarditis.

Recently published results of a large, carefully conducted retrospective study indicated that use of the antibiotic azithromycin (Zithromax, and others) may increase the risk of cardiovascular death, especially in patients with a high baseline risk of cardiovascular disease.1 One possible mechanism is prolongation of the QT interval, which is known to occur rarely with azithromycin and more frequently with the other macrolide antibiotics erythromycin (Erythrocin, and others) and clarithromycin (Biaxin, and others).

Among the patients who received 347,795 prescriptions for azithromycin, there were 29 cardiovascular deaths, a significantly higher rate than the 42 that occurred among the patients who received 1,348,672 prescriptions for amoxicillin (which does not prolong the QT interval) or the 41 that occurred among the 1,391,180 patients who took no antibiotics. Among patients with the highest baseline risk of cardiovascular disease, treatment with azithromycin, compared to amoxicillin, would have resulted in 245 additional cardiovascular deaths per million courses of the antibiotic.

As with any retrospective study, there could have been some undetected differences between the patients who received one drug or the other, but use of an appropriate non-macrolide alternative2 instead of azithromycin might be reasonable in patients with cardiovascular disease or in those who are taking other drugs that can prolong the QT interval (www.azcert.org).

1. WA Ray et al. Azithromycin and the risk of cardiovascular death. N Engl J Med 2012; 366:1881.

2. Drugs for bacterial infections. Treat Guidel Med Lett 2010; 8:43.

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Patients planning to travel to other countries often ask for information about appropriate vaccines and prevention of diarrhea and malaria. More detailed advice for travelers is available from the Centers for Disease Control and Prevention (CDC) at www.cdc.gov/travel. Guidelines are also available from the Infectious Diseases Society of America (IDSA).

The FDA has approved ceftaroline fosamil (Teflaro – Forest), an intravenous (IV) cephalosporin, for treatment of acute bacterial skin and skin structure infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA), and for treatment of community-acquired bacterial pneumonia in adults. It is the first beta-lactam antibiotic approved for treatment of MRSA.

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. The drugs of choice, their dosages and alternatives are listed in a table that begins on page 54. A table listing the adverse effects of some of these antimicrobials begins on page 58.

Patients planning to travel to other countries often ask physicians for information about appropriate vaccines and prevention of diarrhea and malaria. Guidelines are also available from the Infectious Diseases Society of America (IDSA).

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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The most common cause of travelers' diarrhea, usually a self-limited illness without fever lasting several days, is infection with noninvasive enterotoxigenic (ETEC) or enteroaggregative (EAEC) strains of Escherichia coli. Campylobacter, Shigella, Salmonella, Aeromonas, viruses and parasites are less common.

The CDC recently reported that fluoroquinoloneresistant strains of Neisseria meningitidis have been detected for the first time in the US in an area around the border of North Dakota and Minnesota (CDC. MMWR, Feb 22, 2008). These isolates were all serogroup B, for which meningococcal vaccines (Med Lett Drugs Ther 2005; 47:29) do not offer protection. Since many laboratories do not test N. meningitidis for antimicrobial susceptibility, it is possible that such resistance is more widespread.

A single oral dose of ciprofloxacin (Cipro, and others) 500 mg has been used for prophylaxis after close contact with infected patients. Oral rifampin (Rifadin, and others) 600 mg (10 mg/kg for children) q12h for 2 days, a single IM injection of ceftriaxone (Rocephin, and others) 250 mg (125 mg for children), or a single oral dose of azithromycin (Zithromax, and others) 500 mg (10 mg/kg for children) are reasonable alternatives.

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On page 100 of the article "Major Changes in Endocarditis Prophylaxis for Dental, GI and GU Procedures", under the section Highest-Risk Procedures, the word "rubber" should have been omitted. Placement of orthodontic rubber bands is not a highest-risk procedure that justifies prophylaxis; placement of orthodontic (metal) bands is. An orthodontic band is a metal ring that surrounds the tooth and is pressed into place causing movement in closely-spaced teeth and sometimes bleeding when the bands are placed close to the gumline.

The American Heart Association has issued its revised guidelines for prevention of infective endocarditis. Antimicrobial prophylaxis for dental procedures is now recommended only for patients at the highest risk of severe consequences from endocarditis who are undergoing the highest-risk procedures. Endocarditis prophylaxis is no longer recommended for gastrointestinal (GI) and genitourinary (GU) procedures. When these changes are implemented, the number of patients receiving antimicrobial prophylaxis to prevent endocarditis should decline sharply.

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. Guidelines are available from the US Centers for Disease Control and Prevention (CDC) with detailed recommendations for treatment of these diseases.

Information about empirical treatment of bacterial infections, emerging trends in antimicrobial resistance, new drugs and new data about older drugs continue to become available. Usual pathogens and empiric treatment for some common types of infections are summarized in the text and a table listing the drugs of choice and alternatives for each pathogen begins on page 40. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

Many physicians believe that antimicrobial prophylaxis before procedures that may cause transient bacteremia can prevent endocarditis and prosthetic joint infection in patients at increased risk for these disorders. The effectiveness of this common practice has never been established by controlled trials in humans.

Lyme disease in North America is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by Ixodes scapularis or pacificus ticks. These ticks may also carry other pathogens; coinfection with Babesia microti or Anaplasma phagocytophilum (formerly Ehrlichia) has been reported.1 In 2001 and 2002, 12 states (CT, DE, ME, MD, MA, MI, NH, NJ, NY, PA, RI, WI) reported about 95% of all the Lyme disease in the US, but cases occurred in all states except HI, MT and OK. Most Lyme disease in North America occurs between May and September.

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. Guidelines are available from the US Centers for Disease Control and Prevention (CDC) with detailed recommendations for treatment of these diseases (MMWR Recomm Rep 2002; 51, RR-6:1). New guidelines are expected soon.

Gemifloxacin (Factive - Oscient), a new oral fluoroquinolone antibiotic, has been approved by the FDA for 5 days' treatment of acute bacterial exacerbations of chronic bronchitis (ABECB) and 7 days' treatment of mild to moderate community-acquired pneumonia (CAP) in adults. For the next 6-8 months it will only be available, presumably for commercial reasons, in states east of the Rocky Mountains.

Rifaximin (Xifaxan - Salix), a non-absorbed oral antibiotic derived from rifampin (Rifadin, and others), has been approved by the FDA for treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in patients 12 years of age or older. It has been available in Europe since 1987.

Telithromycin (Ketek - Aventis) has been approved by the FDA for oral treatment of mild to moderate community-acquired pneumonia, acute exacerbations of chronic bronchitis and acute bacterial sinusitis in patients age 18 and older. The drug is the first in a new class of antibiotics, the ketolides, derived from the macrolide erythromycin. Telithromycin has been marketed in Europe since 2001.

Parasitic infections are found throughout the world. With increasing travel, immigration, use of immunosuppressive drugs and the spread of AIDS, physicians anywhere may see infections caused by previously unfamiliar parasites. The table below lists first-choice and alternative drugs for most parasitic infections. The brand names and manufacturers of the drugs are listed in this article.

New drugs for bacterial infections and new information about older drugs continue to become available. Empirical treatment of some common bacterial infections is discussed in this article. A table listing the drugs of choice and alternatives for each pathogen begins on page 18. These recommendations are based on results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants. Local resistance patterns should be taken into account. Trade names are listed on page 24.

The choice of drugs for treatment of pneumonia depends on the most likely pathogens causing the infection and local antimicrobial resistance patterns. Factors such as severity of illness, presence of co-morbid conditions and whether the infection is community or hospital-acquired also need to be considered.

Augmentin XR (GlaxoSmithKline), an oral extended-release combination of amoxicillin and the beta-lactamase inhibitor clavulanic acid, is now being promoted for treatment of acute bacterial sinusitis and community-acquired pneumonia. Augmentin XR contains a higher dose of amoxicillin than Augmentin.

Patients planning to travel to other countries often ask physicians for advice about immunizations and prevention of diarrhea and malaria. More detailed advice for travelers is available from the CDC at 877-FYI-TRIP (877-394-8747) or www.cdc.gov/travel.

Lyme disease is caused by the spirochete Borrelia burgdorferi and transmitted to humans by Ixodes ticks. These ticks may also carry other pathogens; co-transmission of Babesia and Ehrlichia species has been reported.

Gatifloxacin and moxifloxacin are now available for once-daily treatment of patients with community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, or acute sinusitis.

Many infections can be transmitted during sexual contact. The text and tables [in this article] are limited to treatment of non-HIV infections associated primarily with sexual transmission.

Combination antiretroviral therapy including protease inhibitors has dramatically changed the treatment of HIV infection and the prognosis of those affected (Medical Letter Handbook of Antimicrobial Therapy, 1998, page 122). Due to limitations and failures with these drugs in many patients, however, three new drugs, none of them protease inhibitors, have rapidly come into wide use in clinical trials or 'expanded access' programs. They are abacavir (Ziagen - Glaxo Wellcome), adefovir (Preveon - Gilead) and efavirenz (Sustiva - DuPont). Efavirenz was recently approved for treatment of adults and children by the FDA. Abacavir has been recommended for approval by an FDA advisory committee.

Cefdinir (Omnicef - Parke-Davis), a third-generation oral cephalosporin, has been approved by the FDA for treatment of acute sinusitis, otitis media, acute exacerbations of chronic bronchitis, pharyngitis, community-acquired pneumonia and skin infections. Other drugs available for these indications are reviewed in The Medical Letter Handbook of Antimicrobial Therapy, 1998.

Grepafloxacin (Raxar - Glaxo Wellcome), a once-daily oral fluoroquinolone, is now being marketed for treatment of community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, uncomplicated gonorrhea, and nongonococcal urethritis and cervicitis.

Ceftibuten (Cedax - Schering), an oral cephalosporin similar to cefixime (Suprax - Medical Letter, 31:73, 1989), has been approved by the US Food and Drug Administration (FDA) for treatment of acute otitis media, pharyngitis or tonsillitis, and for acute bacterial exacerbations of chronic bronchitis.

Dirithromycin (Dynabac - manufactured by Lilly, distributed by Bock), an oral macrolide antibiotic chemically similar to erythromycin, clarithromycin (Biaxin) and azithromycin (Zithromax), has been approved for marketing by the US Food and Drug Administration (FDA).

Results of recently completed clinical trials have led to some changes in recommendations for treatment of human immunodeficiency virus (HIV) and other infections associted with AIDS.

Loracarbef (Lorabid - Lilly), a new beta-lactam antibiotic with antimicrobial activity similar to the second-generation cephalosporins, has been approved by the US Food and Drug Administration for treatment of respiratory, skin, and urinary tract infection caused by susceptible organisms in both adults and children. It will probably compete with drugs such as trimethoprim-sulfamethoxazole (Bactrim, Septra, and others), amoxicillin-clavulanic acid (Augmentin), cefaclor (Ceclor), cefuroxime axetil (Ceftin), and cefprozil (Cefzil - Medical Letter, 34:63, 1992).

Clarithromycin (Biaxin - Abbott) and azithromycin (Zithromax - Pfizer), two macrolide antibiotics chemically related to erythromycin, have been approved by the US Food and Drug Administration for treatment of respiratory, skin, and skin structure infections. Azithromycin has also been approved for treatment of nongonococcal urethritis and cervicitis caused by Chlamydia trachomatis.