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 FDA has announced that it is requiring changes in the labeling of systemic fluoroquinolones to warn that the risk of serious adverse effects, including tendinitis, peripheral neuropathy and CNS effects, generally outweighs their benefit for the treatment of acute sinusitis, acute exacerbations of chronic bronchitis, and uncomplicated urinary tract infections. For these infections, the new labels will recommend reserving fluoroquinolones for patients with no other treatment options.

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.

A reader suggested that our July 23 article on Drugs for Urinary Tract Infection (Med Lett Drugs Ther 2012; 54:57)¹ should have included information on the cost of the drugs we recommended for treatment of acute uncomplicated cystitis.

Trimethoprim/sulfamethoxazole DS — Generic formulations are available at large discount pharmacies for $4 for 20 tablets. Trimethoprim/sulfamethoxazole DS is generally found on tier 1 (lowest co-pay) of insurance company formularies.

Nitrofurantoin monohydrate/macrocrystals — The wholesale acquisition cost of the generic formulation is about $2.50 per tablet (PricePointRx™).² The drug is on tier 1 of some insurance company formularies, but on tier 2 or 3 of others.

Fosfomycin — Available only as Monurol, a single dose of fosfomycin is effective in most cases of acute uncomplicated cystitis, but the manufacturer charges a wholesale acquisition cost of more than $40 for that dose (PricePointRx™).² Most insurance companies place Monurol on tier 3 of their formularies, or do not include it on their formularies at all.

Not recommended: Ciprofloxacin – Fluoroquinolones should not be used empirically to treat acute uncomplicated cystitis. The fact that ciprofloxacin is available at large discount pharmacies for $4 for 20 500-mg tablets and is on tier 1 on most insurance company formularies may be part of the reason for its continued overuse.

1. Drugs for urinary tract infection. Med Lett Drugs Ther 2012; 54:57.

2. PricePointRx™. Reprinted with permission by FDB. All rights reserved. ©2012. http://www.firstdatabank.com/support/drug-pricing-policy.aspx. Accessed July 31, 2012. Actual retail prices may be higher.

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The most recent guidelines from the Infectious Diseases Society of America (IDSA) and its European counterpart on the choice of antimicrobials for treatment of uncomplicated urinary tract infections (UTIs) in non-pregnant women focus on the unnecessary use of fluoroquinolones to treat uropathogens that are increasingly becoming resistant to them. Resistance of Escherichia coli to ciprofloxacin in the US has increased from 3% in 2000 to 17.1% in 2010.

The text below reviews some common bacterial infections and their treatment. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

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.

The physiologic changes that occur with aging can affect the pharmacokinetics and pharmacodynamics of many prescription and over-the-counter drugs, increasing the likelihood of adverse effects.

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.

Fosfomycin, a broad-spectrum antibiotic used parenterally in Europe for many years, has been approved by the US Food and Drug Administration (FDA) as fosfomycin tromethamine (Monurol - Forest) for single-dose oral treatment of uncomplicated urinary tract infections in women.

Some commonly used systemic drugs that may cause pulmonary toxicity are listed in the table below. These adverse effects may sometimes be difficult to distinguish from the underlying disease (JAD Cooper, Jr et al, Am Rev Respir Dis, 133:321, 488, 1986). Pulmonary effects that are part of a generalized reaction or are indirect effects of drugs - on respiratory muscles, for example, or on the immune system - are not included here.