These organisms generally cause a spectrum of disease similar to that caused by other GNB, including pneumonia (particularly ventilator-associated), UTI (especially catheter-related), intravascular device-related infection, surgical-site infection, and abdominal infections.
- Citrobacter, Morganella, and Providencia infections are generally associated with UTIs.
- Acinetobacter has caused soft tissue and bone infections among soldiers with battlefield injuries and is a well-known pathogen in burn units.
Treatment: Infections Caused by Other Gram-Negative Enteric Pathogens - Significant antibiotic resistance among these organisms makes therapy challenging.
- - Many of these organisms (e.g., Serratia, Providencia, Acinetobacter, Citrobacter, Enterobacter, Morganella) have a derepressible AmpC β-lactamase that results in resistance to third-generation cephalosporins, monobactams, and—in many cases—β-lactam/β-lactamase inhibitor combinations.
- - Morganella and Providencia are inherently resistant to the polymyxins and tigecycline.
- Carbapenems and amikacin are most reliably active, and fourth-generation cephalosporins are active provided the organism does not express an ESBL. Susceptibility testing is essential. Some isolates may retain susceptibility only to colistin and polymyxin B.
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