Laboratory Processing of Specimens

Abstract

Serogrouping and typing methodologies are included and these procedures are encouraged, when resource levels at the laboratory permit. (S. Typhi is included in Chapter VII; Shigella is included in Chapter VIII; and, V. cholerae is included in Chapter IX.) Determination of antimicrobial susceptibility patterns not only helps shape successful treatment plans for individual patients but also assists with the development of public health policy for populations at risk for exposure. As mentioned in the introduction to this laboratory manual, because antimicrobial susceptibility testing is so resource intensive and requires a consistent investment in laboratory infrastructure and quality control, the World Health Organization (WHO) recommends that antimicrobial susceptibility testing occur at only one or two laboratories in a country with limited resources. Antimicrobial susceptibilities should be determined for the first 30 to 50 isolates identified by the laboratory at the beginning of an epidemic. Peripheral laboratories may perform initial isolation of Salmonella (including serotype Typhi), Vibrio, and Shigella isolates, and then refer isolates to the central or national reference laboratory for final confirmation and determination of antimicrobial susceptibility. Peripheral laboratories may also be the sites of focused studies to determine etiologic agents causing an outbreak. First-level laboratories should be supplied with transport medium and the means of sending the specimens to the next level laboratory or to the central laboratory.