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.

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.

A reader has questioned why the label for the COX-2 selective NSAID celecoxib (Celebrex, and generics), which contains a sulfonamide moiety, states that it is contraindicated for use in patients with an allergy to sulfonamides, while the labels of some other sulfonamide drugs recommend either caution or no precautions at all. The concept of cross-reactivity among sulfonamide drugs, particularly between antibacterial and nonantibacterial sulfonamides, has been controversial for many years.

The FDA has approved Vowst (Seres Therapeutics/Nestle HealthScience), an oral capsule containing live fecal microbiota spores, for prevention of additional recurrences of Clostridioides difficile infection (CDI) in adults. Vowst is the first orally administered microbiota-based treatment to be approved for this indication. A rectally-administered live fecal microbiota-based suspension (Rebyota) was approved in 2022 for the same indication. Neither product is approved for acute treatment of CDI.

The FDA has approved Xacduro (Innoviva), a combination of the beta-lactam antibacterial sulbactam and the beta-lactamase inhibitor durlobactam, for IV treatment of adults with hospital-acquired or ventilator-associated bacterial pneumonia caused by susceptible isolates of Acinetobacter baumannii-calcoaceticus complex (ABC).

The FDA is requiring new warnings about peripheral neuropathy in the labeling of all oral and injectable fluoroquinolones. The potential for this class of antibiotics to cause peripheral neuropathy was first identified more than 10 years ago and a warning was added to their labels in 2004. The new warnings are based on a recent review of the FDA’s Adverse Event Reporting System (AERS) database.1The onset of peripheral neuropathy can occur rapidly, often within a few days of starting a fluoroquinolone, and in some patients the disorder may be permanent. Symptoms include pain, tingling,...

The FDA has approved azithromycin 1% ophthalmic solution (AzaSite - Inspire) for treatment of bacterial conjunctivitis in patients > 1 year old. It is formulated, according to the manufacturer, in a controlled-release delivery system that keeps the drug in the eye for several hours.

The FDA has approved the fully human monoclonal antibody bezlotoxumab (Zinplava – Merck) for use with antibacterial drug treatment to reduce recurrence of Clostridium difficile infection (CDI) in adults with CDI at high risk for recurrence. It is the first drug to be approved for this indication.

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...