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.

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.

Meropenem (Merrem - Zeneca), a carbapenem similar to imipenem-cilastatin (Primaxin), has been approved by the US Food and Drug Administration for intravenous (IV) treatment of complicated intra-abdominal infections in adults and children and bacterial meningitis in children more than three months old. Imipenem (Medical Letter, 28:29, 1986) has been useful for treatment of serious infections in which broad coverage of nosocomial organisms, including anaerobes, is needed. Other drugs for these indications were reviewed in the Medical Letter article on 'The Choice of Antibacterial Drugs' (volume 38, page 25, March 29, 1996).

Cefepime hydrochloride (Maxipime - Bristol-Myers Squibb), a new 'fourth-generation' cephalosporin, has been approved by the US Food and Drug Administration (FDA) for parenteral treatment of urinary tract infections and skin and skin-structure infections due to susceptible pathogens, and for moderate to severe pneunmonia caused by Streptococcus pneumoniae (pneumococci), Pseudomonas aeruginosa, Enterobacter or Klebsiella pneumoniae.

Piperacillin/tazobactam (Zosyn - Lederle), an antibiotic combination product, has been approved by the US Food and Drug Administration for intravenous treatment of intra-abdominal, pelvic, skin, and skin-structure infections and for community-acquired pneumonia of moderate severity.

Altretamine (Hexalen - US Bioscience; Hexastat - Rh ne-Poulenc in Canada), formerly known only by its chemical name, hexamethylmelamine, was recently approved by the US Food and Drug Administration as a single agent for palliative oral treatment of persistent or recurrent ovarian cancer.

A penicillin is the drug of choice for treatment of many infections, but allergic reactions to these drugs occur frequently and, rarely, can be fatal. From 5% to 20% of patients have a history of a rash or some other reaction while taking a penicillin, but maculopapular rashes with ampicillin or amoxicillin, especially in children with infectious mononucleosis, are probably not allergic.

Ciprofloxacin hydrochloride (Cipro - Miles), a synthetic antibacterial agent, was recently marketed in the USA for oral treatment of a wide variety of infections. Ciprofloxacin is the second fluoroquinolone to become available in this country; norfloxacin (Noroxin - Medical Letter, 29:25, 1987) is marketed only for treatment of urinary tract infections. Fluoroquinolones are more potent and have a much broader spectrum of activity than older quinolones such as nalidixic acid (NegGram).