Acinetobacter baumannii Emerging as a Multidrug-Resistant Skin and Soft-Tissue Pathogen: Parallels to Methicillin-Resistant Staphylococcus aureus

Over the last 30 years, the gram-negative coccobacillus Acinetobacter baumannii has risen to microbiologic notoriety for its ability to successfully evade nearly all available antibiotics. It is now a well-established source of nosocomial bacteremia and pneumonia, known to cause hospital outbreaks, particularly in the intensive care unit. Less often it represents a source of nosocomial skin and soft-tissue infection (SSTI) in the setting of war wounds, surgical sites, and burns.¹

Most reports of A baumannii infection, both nosocomial and community-acquired (CA) SSTI, involve cellulitis of peau d’orange appearance with overlying vesicles that, when untreated, progress to necrotizing fasciitis with coalescent bullae.² The condition is uncommon and has been reported solely in compromised hosts.³ To our knowledge, A baumannii has never been reported as a cause of CA-SSTI in a healthy patient.

However, unpublished and anecdotal cases of increasingly drug-resistant A baumannii presenting as SSTI in healthy patients are known to exist. Molecular typing experiments reveal community and nosocomial A baumannii isolates to be genetically distinct, existing as separate reservoirs with unique virulence and resistance patterns. Until recently, multidrug resistance was considered a hospital-based phenomenon.⁴ We report herein the case of a healthy woman with CA multidrug-resistant A baumannii.

A woman in her 50s with no comorbidities or history of hospitalization presented with tender, violaceous, indurated dermal plaques with central ulceration and peripheral erythema and edema (Figure, A) that had progressively enlarged over the previous 7 to 8 months. Tissue culture results were specific for A baumannii with sensitivity to polymyxin B and tigecycline. The patient was admitted for treatment with intravenous tigecycline and discharged to home with an inpatient-administered peripherally inserted central catheter to facilitate a subsequent 2 weeks of treatment. Following treatment, the patient underwent extensive wound care for 6 months prior to reepithelialization with resulting scarring, dyschromia, and neuropathic pain (Figure, B).

The evolution of A baumannii infection bears a striking similarity to the now established methicillin-resistant Staphylococcus aureus (MRSA) epidemic; MRSA was initially regarded as a nosocomial pathogen transmitted between health care facilities and limited to a small number of strains with distinct virulence patterns. While the first CA cases occurred in those with predisposing risk factors, it eventually began appearing in healthy patients. Over time, CA-MRSA incorporated new virulence patterns, acquiring large-scale antibiotic resistance, while maintaining a unique genetic profile compared with nosocomial isolates. Better appreciated through a retrospective lens, this CA form rivals its hospital-based counterpart and can aptly be considered an epidemic.⁵

A baumannii has the potential to evolve in a pattern similar to that of MRSA and should be monitored for growing resistance and virulence. Epidemiologic history has demonstrated how quickly an organism can evolve from benign commensal to resistant pathogen and highlights the need for intense vigilance with regard to infection control and treatment development.¹ With continued accrual of pathogenicity and antibiotic resistance, A baumannii is offering new diagnostic and therapeutic challenges. Enhanced awareness is paramount to control this growing threat as the practice gap continues to widen.

Corresponding Author: Adam J. Friedman, MD, Division of Dermatology, Montefiore Medical Center, 111 E 210th St, Bronx, NY 10467 (adfriedm@montefiore.org).

Published Online: June 18, 2014. doi:10.1001/jamadermatol.2013.8855.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was supported in part by the Dermatology Foundation.

Role of the Sponsors: The Dermatology Foundation had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Information: Mr Adler and Ms Krausz contributed equally to this work.