A 52-year-old man was admitted to a local hospital with headache, nausea, vomiting, dizziness, photophobia, and confusion after a sudden fall. Progressive changes in neurologic function were noted despite neurosurgical intervention and broad-spectrum antimicrobial coverage. Cerebral spinal fluid (CSF) culture identified Acinetobacter baumannii that was resistant to traditionally recommended therapies of amikacin and imipenem-cilastatin. The organism demonstrated minimum inhibitory concentrations of greater than 32 microg/ml and 8 microg/ml, respectively, for these two agents. Ampicillin 2 g-sulbactam 1 g every 3 hours was administered based on history of therapeutic failure of traditional dosing in our thermal injury population. Repeat CSF cultures after 12 days of ampicillin-sulbactam therapy were negative. After 35 days, the patient's A. baumannii infection was completely resolved. The patient experienced no adverse drug events or toxicity with this high-dosage regimen.

Legionella pneumophila, a Gram-negative bacillus, is the causative agent of Legionnaire’s disease, a form of severe community-acquired pneumonia. Infection can have high morbidity, with a high proportion of patients requiring ICU admission, and up to 10% mortality, which is exacerbated by the lack of efficacy of typical empirical antibiotic therapy against Legionella spp. The fastidious nature of the entire Legionellaceae family historically required inclusion of activated charcoal in the solid medium to remove growth inhibitors, which inherently interferes with accurate antimicrobial susceptibility determination, an acknowledged methodological shortfall, now rectified by a new solid medium that gives results comparable to those of microbroth dilution. Here, as an international Legionella community (with authors representing various international reference laboratories, countries and clinical stakeholders for diagnosis and treatment of legionellosis), we set out recommendations for the standardization of antimicrobial susceptibility testing methods, guidelines and reference strains to facilitate an improved era of antibiotic resistance determination.