It's Bordetella, It's Alcaligenes… No, It's Achromobacter! Identification, Antimicrobial Resistance, and Clinical Significance of an Understudied Gram-Negative Rod

Abstract

Gram-negative non-fermentative bacilli, such as Achromobacter spp., can be opportunistic pathogens in nosocomial settings. Widely found in nature, Achromobacter spp. cause a broad spectrum of diseases and are best known as emerging opportunistic pathogens in the lungs of cystic fibrosis patients. Importantly, Achromobacter infections represent a diagnostic and clinical challenge. First, clinical laboratories cannot routinely identify Achromobacter isolates reliably to the species level outside of creating and curating a custom mass spectrometry database or using Achromobacter-specific genotypic molecular methods. Additionally, Achromobacter spp. infections are often difficult to treat owing to numerous intrinsic, and to a lesser extent acquired, antimicrobial resistance mechanisms. Treatment decisions are further complicated by discordance between CLSI and EUCAST breakpoints for antimicrobial susceptibility testing of Achromobacter isolates, and collaboration to harmonize these is necessary. Further studies are also needed to define the clinical spectrum of disease and pathogenic potential of many Achromobacter species.