ESBLs and Acinetobacter: The Other Important Threats


The prevalence of extended spectrum beta-lactamases (ESBLs) is increasing throughout U.S. hospitals, warns Carlene Muto, MD, medical director of the Department of Hospital Epidemiology and Infection Control at the University of Pittsburgh Medical Center. "Not only are ESBLs troublesome, there’s resistant acinetobacter to worry about," Muto says.

Acinetobacter baumannii is an aerobic, gram-negative coccobacillary rod found on skin as well as in soil and water that multiplies at various temperatures and pH environments and employs myriad substrates for growth. The recent development of resistance intensifies its emergence and significance in healthcare environments. Acinetobacter baumannii is associated with hospital-acquired infections (HAIs) with significant associated clinical and economic costs.

"Although the method of resistance is a bit different, these kinds of pathogens are increasing in healthcare facilities," Muto says. "The outreach of an infection prevention program is important, as are strict transmission-based precautions and an antibiotic-management program. For gram-positive organisms like methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE), transmission-based precautions seem to be weighted a bit more; for the gram-negatives, antibiotic stewardship becomes critical."

Once the organism is induced, Muto says, it will spread throughout a hospital just like MRSA and other multidrug-resistant organisms (MDROs), so prompt identification of the pathogen and implementation of transmission-based precautions becomes paramount. "Although my hospital is not screening for ESBLs right now, we do have real-time alerts as soon as one is identified so we can put the transmission-based precautions into place," Muto says. "The same steps apply to acinetobacter. We will probably continue to look at the trends and see if doing active surveillance will be beneficial. It’s like VRE—you would probably look at the intestinal flora of the stool. Screening methods still have to be developed, as there’s nothing that would easily identify an ESBL on any screening right now."

Muto adds, "When we did have our first case of resistant acinetobacter, we took many actions, including doing some screening; we thought if there was some reservoir of cases that was not obvious, we should try to discover it. There was nothing in the literature that helped guide us on what media to use or what sites of the body to sample, but we did the screening and didn’t identify any other cases. It was probably because we had containment measures already in place when we did the screening so we were preventing further transmission. But each time we are challenged with the emergence of another pathogen, we are going to have to figure out what will be necessary to make sure this doesn’t become the next MRSA."

A baumannii infections can be fatal in immuno-compromised patients who have multiple comorbid conditions, are hospitalized for long periods, or have multiple invasive procedures. A baumannii is a significant HAI because it has a diverse reservoir, is antimicrobial resistant, and has a significant capacity for outbreaks. Acinetobacter baumannii can survive for long periods on both dry and moist surfaces, necessitating thorough and proper cleaning and disinfection of patient-care equipment and environmental surfaces in the healthcare setting. Insufficient hand hygiene remains a significant factor in the transmission of acinetobacter. Colonization on the skin and contamination on hand and glove surfaces may be direct or indirect as the healthcare provider touches the patient and environmental surfaces during care. Acinetobacter can be eradicated by most hand-cleansing agents and by proper environmental cleaning.


Montefour K, et al. Acinetobacter baumannii: an emerging multidrug-resistant pathogen in critical care. Crit Care Nurse 2008 Feb; 28(1):15-25.

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