Comparison of the Clinical Efficacy of Ampicillin/Sulbactam and Cefoperazone/Sulbactam Against Multidrug Resistant Acinetobacter Baumannii Infections in Critically Ill Patients

Among Acinetobacter species, Acinetobacter baumannii is the most important member and is commonly implicated in nosocomial infections. Acinetobacter baumannii is a gram-negative coccobacillus that has emerged from an organism of questionable pathogenicity to an infectious agent of importance to hospitals worldwide. In the intensive care unit ICU setting, Acinetobacter baumannii has been implicated in severe and occasionally life-threatening infections such as ventilator-associated pneumonia and bloodstream infections. Acinetobacter baumannii can produce biofilms in environments exposed to antibiotics; thus, it can survive for long periods and easily develop multidrug (MD), extremely or extensively drug (XD), and even pan-drug resistances (R) to various types of antibiotics, resulting in high patient mortality.

The underlying mechanisms can be divided into three categories. First, A. baumannii produces decomposition enzymes that deactivate antibiotics. Second, it can reduce or hinder the entry of antibiotics. For example, A. baumannii prevents the entry of antibiotics by controlling efflux pumps, or it can remove the antibiotics that have entered the cells. Third, point mutations alter the targets or functions of bacteria and reduce their affinity for antibiotics. Owing to its strong infectivity and drug resistance, A. baumannii has been added to the list of the World Health Organization's antibiotic-resistance priority pathogens.

Sulbactam, a beta-lactamase inhibitor, is commercially available mainly in combination with β-lactam antibiotics (as in ampicillin-sulbactam or cefoperazone-sulbactam), is a drug containing a beta-lactam ring derived from 6-aminopenicllanic acid. It can bind to the active sites of b-lactamase antibiotics to protect against antibiotic hydrolysis and restore antibiotic activity.

The antimicrobial property distinguishing sulbactam from other beta-lactamase inhibitors is its activity against Acinetobacter spp. Therefore, sulbactam is an alternative treatment option due to the worldwide spread of multidrug resistance Acinetobacter baumannii, for which only a few effective antimicrobial agents are currently available. The Infectious Diseases Society of America Antimicrobial-Resistant Treatment Guidance suggests that high-dose ampicillin-sulbactam (total daily dose of 6-9 grams of the sulbactam component) be included in the combination therapy regimen. If ampicillin-sulbactam non-susceptibility is shown, high-dose ampicillin-sulbactam can still be a helpful therapy choice. Acinetobacter baumannii isolates in China were more susceptible to cefoperazone-sulbactam than to ampicillin-sulbactam (resistance rates 48.8% vs 59.1%). The literature's limited data indicated that patients with Acinetobacter baumannii may expect moderate clinical benefits with Cefoperazone -Sulbactam. Salvation therapy may be attempted with combination treatment, particularly with polymyxins. There are no randomized controlled studies investigating the effectiveness of cefoperazone-sulbactam in the presence or absence of polymyxins for Acinetobacter baumannii infections.