What antibiotics is Enterobacter cloacae susceptible to?

Antibiotic Susceptibility of Enterobacter cloacae

Carbapenems (meropenem and imipenem) are the most effective antibiotics against Enterobacter cloacae, with fourth-generation cephalosporins (cefepime) being an alternative option when Extended-Spectrum Beta-Lactamase (ESBL) is absent. 1

First-line Treatment Options

• Carbapenems represent the most valid therapeutic option for multidrug-resistant Enterobacter infections 1
• Meropenem and imipenem are specifically effective against E. cloacae 1, 2
• Ertapenem is also effective against E. cloacae, including some ESBL-producing strains, though with higher resistance rates than other carbapenems 3, 4

Resistance Patterns and Considerations

• First and second-generation cephalosporins are generally not effective against Enterobacter infections 1
• Third-generation cephalosporins are not recommended due to increased likelihood of resistance, particularly for E. cloacae 1, 5
• Fourth-generation cephalosporins (cefepime) could be used if ESBL is absent 1, 6
• When using newer MIC interpretive breakpoints for carbapenems, an additional 27% of E. cloacae isolates were found to be non-susceptible to ertapenem compared with older criteria 1, 3

Treatment Algorithm for E. cloacae Infections

1. First-line therapy: Carbapenems (meropenem or imipenem) 1, 2, 7
2. Alternative therapy: Fourth-generation cephalosporins (cefepime) if ESBL-negative 1, 6
3. For carbapenem-resistant E. cloacae: Consider combination therapy with polymyxins, tigecycline, fosfomycin, or double carbapenem regimen 1

Special Considerations

• Imipenem has shown superior resistance prevention properties compared to other beta-lactams, with studies showing it did not select for resistance in E. cloacae strains during testing 5
• Meropenem selects resistance at a slower rate than most cephalosporins but faster than imipenem 5
• Recent studies (2023) have reported emerging resistance to carbapenems in E. cloacae, particularly after the COVID-19 pandemic, highlighting the need for antimicrobial stewardship 8
• For urinary tract infections caused by E. cloacae, carbapenems (meropenem, imipenem, and ertapenem) remain largely effective, though increasing resistance is a concern 4

Pitfalls and Caveats

• Automated susceptibility testing systems may have limitations in detecting ESBL-producing organisms using newer interpretive criteria 6
• The new ceftazidime and cefepime susceptible breakpoints fail to identify many ESBL-producing Enterobacteriaceae 6
• Resistance mechanisms in E. cloacae often involve both reduced outer membrane permeability and high-level cephalosporinase production working together 9
• Regular monitoring of susceptibility patterns is essential as resistance profiles can change rapidly, especially in healthcare settings 10