Achromobacter species (CDC group Vd): morphological and biochemical characterization

Area of Science:

• Microbiology
• Bacteriology
• Clinical Diagnostics

Background:

• Achromobacter species, formerly CDC group Vd, are gram-variable bacilli with complex morphological and biochemical characteristics.
• Accurate identification of Achromobacter is crucial for clinical and epidemiological studies.

Purpose of the Study:

• To conduct a detailed morphological and biochemical characterization of Achromobacter species isolates.
• To evaluate the efficacy of various miniaturized identification kits in identifying Achromobacter species.

Main Methods:

• Morphological analysis using Gram staining and electron microscopy.
• Biochemical profiling including growth on selective media, enzyme production, and carbohydrate utilization.
• Performance evaluation of Minitek, N/F, Oxi/Ferm, and API 20E identification systems.

Main Results:

• Gram stains revealed gram-variable, coryneform bacilli with polar flagella and extracellular material.
• Two distinct colony morphologies were observed: mucoid and non-mucoid.
• Biochemical tests showed urease production, nitrate reduction, esculin hydrolysis, phenylalanine deamination, and H2S production.
• Carbohydrate oxidation was weak, primarily limited to glucose and xylose.
• Minitek and N/F kits identified 91% and 83% of isolates, respectively, while Oxi/Ferm and API 20E showed lower identification rates.

Conclusions:

• Achromobacter species exhibit unique morphological and biochemical traits that require careful examination.
• Miniaturized identification kits vary significantly in their ability to accurately identify Achromobacter species.
• The Minitek and N/F systems demonstrated superior performance compared to Oxi/Ferm and API 20E for Achromobacter identification.