Cefmetazole, Flomoxef, and Latamoxef

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These three drugs are cephamycin/oxacephem antibiotics that share similar properties and are often studied together as alternatives to carbapenems for treating infections caused by extended-spectrum β-lactamase-producing bacteria (ESBL-producing bacteria).

Drug Information

Cefmetazole, flomoxef, and latamoxef (also known as moxalactam) are β-lactam antibiotics that are stable against hydrolysis by ESBLs. While cefmetazole is classified as a cephamycin, flomoxef and latamoxef belong to a related class called oxacephems. These antibiotics have been identified as potential carbapenem-sparing options for treating infections caused by ESBL-producing Enterobacterales.

Mechanism of Action

These antibiotics work by inhibiting bacterial cell wall synthesis. They are stable against hydrolysis by extended-spectrum β-lactamases (ESBLs), which makes them effective against ESBL-producing bacteria. However, they can be inactivated by carbapenemases and Class C β-lactamases (AmpC).

Clinical Applications

These antibiotics have been studied for treating various infections, particularly those caused by ESBL-producing Escherichia coli (ESBL-EC). They are considered potential alternatives to carbapenems for:

• Urinary tract infections (UTIs)
• Intra-abdominal infections (IAIs)
• Bloodstream infections caused by ESBL-producing bacteria

Studies have shown high susceptibility rates of ESBL-EC to these antibiotics. For instance, 94.2% of ESBL-EC isolates were susceptible to cefmetazole, and 98.3% were susceptible to flomoxef in one study.

Dosage Regimens

Typical dosage regimens include:

• Cefmetazole: 1 g intravenously every 8 hours
• Flomoxef: 1 g intravenously every 8 hours
• Latamoxef (moxalactam): Various dosing regimens have been studied, including 20, 30, 40, 50, and 60 mg/kg in veterinary medicine

Safety Profile

When cefmetazole is combined with flomoxef, there may be an increased risk of nephrotoxicity. This potential interaction should be considered when administering these antibiotics together.

Comparative Effectiveness

In some studies comparing flomoxef with carbapenems for treating ESBL-producing bacterial infections, flomoxef showed comparable efficacy to carbapenems when the minimum inhibitory concentration (MIC) was low (<1 mg/L). However, for higher MIC levels (2-8 mg/L), carbapenems demonstrated superior outcomes.

Current Status

Flomoxef is being proposed for inclusion on the WHO Model List of Essential Medicines (EML) and Model List of Essential Medicines for Children (EMLc) as a carbapenem-sparing option for treating infections caused by ESBL-producing bacteria. It's worth noting that moxalactam is no longer in use in most countries, and latamoxef is primarily used in Japan.

These antibiotics represent important options in the antimicrobial armamentarium, particularly in the context of increasing antimicrobial resistance and the need for carbapenem-sparing strategies.