Quality in Diagnostic Microbiology: Experiential Note to Emphasize Value of Internal Control Programs

BACKGROUND: Quality control (QC) in diagnostic microbiology is a matter of effective, efficient, accurate reporting in the expected turnaround time. Major stages of the analytical “standard operational procedures” where QC could be easily affected include organism identification and antibacterial susceptibility testing. AIM: The objective of this experiential technical note is to provide an evidence base to highlight the value of internal QC program in evaluating the effectiveness and efficiency of a laboratory's standard operational procedures; and the competences of individual scientific/technical staff. MATERIALS AND METHODS: This report is based on four different scenarios requiring internal QC, including cases that are not reported within the turnaround time of standard operational procedures. Small-scale evaluations of (i) internal QC program, (ii) ciprofloxacin vs. moxifloxacin susceptibilities, and (iii) calibrated dichotomous susceptibility vs. directed susceptibility testing were performed. RESULTS: The internal QC program identified sources of discrepancies in laboratory results. Evidence base for decision on new methodology and antibiotic testing were developed. For instance, it is observed that calibrated dichotomous susceptibility gives greater annular radius than directed susceptibility (P < 0.01). CONCLUSIONS: Internal QC program continues to be valuable means of identifying discrepancies, and vetting new ideas. This report presents evidence base to reaffirm that the need for internal QC is ever present.