| Abiotrophia spp. | Special Bacteriology Unit | Susceptibility Testing | Antimicrobial Susceptibility Testing On Selected Aerobes, Facultative Anaerobes, and Strict Anaerobes | 
| Acinetobacter spp. | Special Bacteriology Unit | Susceptibility Testing | Antimicrobial Susceptibility Testing On Selected Aerobes, Facultative Anaerobes, and Strict Anaerobes | 
| Adenovirus | Influenza and Respiratory Viruses | Molecular Detection | Molecular Detection by PCR or RT-PCR | 
| Adenovirus | Influenza and Respiratory Viruses | Genotyping | Genotyping by PCR and Sequencing | 
| Aerobic Actinomycetes | Special Bacteriology Unit | Susceptibility Testing | Antimicrobial Susceptibility Testing On Selected Aerobes, Facultative Anaerobes, and Strict Anaerobes | 
| Aeromonas spp. | Enteric Diseases Program | Biotyping / Identification | Biotyping / Identification | 
| Anaplasma phagocytophilum | Field Studies, Zoonotic Diseases and Special Pathogens | Molecular Detection | Molecular Detection | 
| Anaplasma phagocytophilum | Field Studies, Zoonotic Diseases and Special Pathogens | Serology | Indirect Immunofluorescent Assay (IFA) – IgG | 
| Andes virus | Special Pathogens | Molecular Detection | Molecular Detection of Andes virus | 
| Andes virus | Special Pathogens | Serology | Detection of antibodies against Andes virus by ELISA | 
| Arcobacter spp. | Enteric Diseases Program | Biotyping / Identification | Phenotypic and Molecular Identification |