The FDA has approved Exblifep (Allecra), a fixed-dose combination of the cephalosporin cefepime and the beta-lactamase inhibitor enmetazobactam, for IV treatment of adults with complicated urinary tract infections (cUTIs), including pyelonephritis, caused by designated susceptible microorganisms (see Spectrum of Activity). Exblifep is the first product that contains enmetazobactam to be approved in the US.

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 FDA has approved cefiderocol (Fetroja – Shionogi), a new IV cephalosporin antibiotic, for treatment of complicated urinary tract infections (UTI) caused by susceptible gram-negative bacteria in adults who have limited or no alternative treatment options.

Eravacycline (Xerava – Tetraphase), a new synthetic tetracycline antibiotic, has been approved by the FDA for IV treatment of complicated intra-abdominal infections (cIAIs) in adults. Eravacycline is structurally similar to tigecycline (Tygacil, and generics), a broad-spectrum tetracycline approved by the FDA for IV treatment of complicated skin and skin structure infections, complicated intra-abdominal infections, and community-acquired pneumonia. A higher rate of mortality has been reported with use of tigecycline compared to other antibacterial drugs; it should be used only when no suitable alternative is available.

The FDA has approved the new aminoglycoside antibiotic plazomicin (Zemdri – Achaogen) for IV treatment of adults with complicated urinary tract infections (cUTIs). Plazomicin is active against multi-drug- resistant Enterobacteriaceae, including strains resistant to other aminoglycosides.

The FDA has approved a fixed-dose combination of meropenem, a carbapenem antibiotic, and vaborbactam, a new beta-lactamase inhibitor (Vabomere – Melinta), for IV treatment of adults with complicated urinary tract infections (UTIs) that are proven or strongly suspected to be caused by Escherichia coli, Klebsiella pneumoniae, or Enterobacter cloacae spp. complex. Meropenem (Merrem, and generics) has been approved for years for treatment of complicated skin and skin structure infections, intra-abdominal infections, and bacterial meningitis. Resistance to meropenem and other carbapenems, mainly due to production of carbapenemases and other extended-spectrum beta-lactamases (ESBLs), has been increasing worldwide, particularly among Enterobacteriaceae. Vabomere is the first carbapenem/beta-lactamase inhibitor combination to be marketed in the US.

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 FDA has approved ceftazidime/avibactam (Avycaz – Actavis) for IV treatment of complicated urinary tract and intra-abdominal infections in adults who have limited or no other treatment options. Ceftolozane/tazobactam (Zerbaxa – Cubist), another cephalosporin/beta-lactamase inhibitor combination, was approved in 2014.

The FDA has approved ceftolozane/tazobactam (Zerbaxa – Cubist), a combination of a new cephalosporin antibiotic and a beta-lactamase inhibitor, for intravenous treatment of complicated urinary tract and intra-abdominal infections in adults.

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 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 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.

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.