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.

Cefuroxime axetil (Ceftin - Glaxo), an oral form of the second-generation parenteral cephalosporin cefuroxime (Zinacef), was recently marketed in the USA. Previously available oral cephalosporins are the first-generation drugs cephalexin (Keflex; and others), cephradine (Anspor; and others) and cefadroxil (Duricef; and others), and the second-generation cefaclor (Ceclor); second-generation cephalosporins have more activity against gram-negative bacteria.

Cefpodoxime proxetil (Vantin - Upjohn), a new third-generation oral cephalosporin, has been approved for marketing by the US Food and Drug Administration. It is available for twice-daily treatment of pharyngitis, upper and lower respiratory infections, otitis media, urinary tract infections, skin and soft tissue infections, and for single-dose treatment of uncomplicated gonorrhea in men or women and anorectal gonorrhea in women.

Linezolid, the first of a new class of antibiotics, the oxazolidinones, has been marketed for treatment of infection due to vancomycin-resistant Enterococcus faecium, nosocomial and community-acquired pueumonia due to Staphylococcus aureus or penicillin-sucsceptible Streptococcus pneumoniae, and skin and skin structure infections, including those due to methicillin-resistant S. aureus (MRSA).

Ertapenem (er ta pen' em; Invanz - Merck), a carbapenem antibacterial with a narrower spectrum of activity than imipenem (Primaxin) or meropenem (Merrem), has been approved by the FDA for once-daily IV treatment of complicated intra-abdominal, urinary tract and skin and skin structure infections, acute pelvic infections, and community-acquired pneumonia.

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.

Immune-mediated hemolysis is a rare adverse effect of second- and third-generation cephalosporins, especially cefotetan (Cefotan) (PA Arndt et al, Transfusion 1999; 39:1239). A recent report serves as a reminder that life-threatening immune-mediated hemolysis rarely can follow administration of ceftriaxone (Rocephin), one of the most commonly used parenteral antibiotics in the US (A Citak et al, J Paediatr Child Health 2002; 38:209).

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.

Lyme disease in the US is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by Ixodes scapularis (blacklegged [deer] tick) and I. pacificus (western blacklegged tick). Most cases of Lyme disease occur in late spring and early summer in northeastern and mid-Atlantic states, the upper Midwest, and in northern California. B. mayonii, which is also transmitted by I. scapularis, has been shown to cause a similar illness in the upper Midwest.

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.