CASE REPORT
Bacterial Misidentification in a Resource-Limited Microbiology Laboratory Setting and Quality Improvement Strategies Nuntra Suwantarat, MD,*† Sasinuj Rutjanawech, MD,‡ Aubonphan Buppajarntham, MD,‡ Karen C. Carroll, MD,*† Thana Khawcharoenporn, MD, MSc,‡ and Anucha Apisarnthanarak, MD‡ Key Words: bacteria, misidentification, resource-limited setting, quality improvement (J Patient Saf 2015;00: 00–00)
B
acterial misidentification and misinterpretation of antimicrobial susceptibility test results directly impact patient safety related to inappropriate antibiotic management. Moreover, these problems potentially affect infection control practices such as patient isolation when misidentification involves multidrug-resistant organisms (MDROs).1,2 In Thailand, a highly endemic region of MDRO and carbapenem-resistant Acinetobacter baumannii, accurate microbiological testing is essential to appropriate patient care and good clinical outcomes.3–5 We report misidentification of 7 bacterial isolates during a 1-month period, which was recognized by Infectious Diseases Consultants (IDCs). Infection preventionists (IPs) conducted an investigation and implemented quality improvement (QI) strategies for improving microbiology laboratory workflow and identification protocols.
METHODS Thammasat University Hospital (TUH) is a 650-bed university hospital located in central Thailand. The microbiology laboratory has been operated by 3 technicians and supervised by a technical laboratory supervisor without a doctoral-level clinical microbiologist. The laboratory receives an estimated 3000 specimens for testing per month for bacteriology culture including blood cultures (1500 specimens), respiratory cultures (600 specimens), urine cultures (800 specimens), sterile body fluid cultures (30 specimens), stool cultures (50 specimens), and miscellaneous cultures (50 specimens). The majority of bacterial organisms identified are glucose-nonfermenting gram-negative bacilli (nonfermenters) (300-400 isolates per month) and gram-positive organisms (200-300 isolates per month). Blood cultures are performed using TREK80 media and the VersaTREK system (TREK diagnostics Diagnostics, Oakwood Village, OH). Media for cultures including 5% sheep blood agar (Becton Dickinson, Sparks, MD), MacConkey agar (Becton Dickinson), and Chocolate agar (Oxoid, Ottawa, Canada) were incubated in CO2 and non-CO2 incubators. The bacteriology identification protocol is based on Gram stain interpretation, colony morphology, and conventional biochemical testing. Technicians on service interpret the Gram
From the *Division of Medical Microbiology, Johns Hopkins University School of Medicine; and †Microbiology Laboratory, Johns Hopkins Hospital, Baltimore, MD; and ‡Division of Infectious Diseases, Faculty of Medicine, Thammasat University, Pathumthani, Thailand. Correspondence: Nuntra Suwantarat, MD, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Meyer B1-193 600 N Wolfe St, Baltimore, MD 21287 (e‐mail: [email protected]). The authors disclose no conflict of interest. This study was supported by National Research University Project of the Thailand Office of Higher Education Commission (to A.A. and T.K.) Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Patient Saf • Volume 00, Number 00, Month 2015
stains without double checking results with other technicians and report a Gram stain result directly to primary providers by telephone and in the electronic medical record. Then, antimicrobial susceptibility testing (AST) is performed using Clinical Laboratory and Standards Institute guidelines by disk diffusion testing and E-test (bioMerieux, Marcyl'Etoile, France). Quality control is performed for each new lot of media and biochemical reagents. Temperatures of all incubators are measured daily. The VersaTREK system and AST testing quality control are performed weekly on isolates of Staphylococcus aureus (ATCC 25923, ATCC 29213), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), which were provided by the Thai National Institution of Health (NIH). Bacteriology identification proficiency testing was performed quarterly using unknown isolates from the Thai NIH. The TUH microbiology laboratory's proficiency testing performance had been 100% for 2 years. The TUH infectious disease service gets consulted for every patient who presents with fever and suspected infections. In January 2014, IDCs became aware of several cases of inconsistencies between patient clinical disease and microbiology laboratory results. Infection preventionists conducted an investigation to determine the extent of the misidentifications and to identify factors that contributed to the increase in misidentification. The identification procedures of the suspected misidentified isolates were reviewed. Seven suspected misidentified isolates were submitted to the Thai NIH for final confirmation and identification using the Vitek2 system (bioMerieux) and API 20E system (bioMerieux). Subsequently, new QI strategies for bacteriology identification were implemented. The numbers of misidentified isolates after implementation of QI protocols were recorded.
RESULTS Misidentification of 7 bacterial isolates and patient clinical outcomes during a 1-month period are summarized in Table 1. There was no change in laboratory personnel, and no problems with instruments or reagents were detected. The errors were not traced to a single laboratory technician. The frequency of bacterial misidentification was 1.3% (7/550), which was significantly increased from the previous year (0.08% [6/7554], P
Bacterial Misidentification in a Resource-Limited Microbiology Laboratory Setting and Quality Improvement Strategies Nuntra Suwantarat, MD,*† Sasinuj Rutjanawech, MD,‡ Aubonphan Buppajarntham, MD,‡ Karen C. Carroll, MD,*† Thana Khawcharoenporn, MD, MSc,‡ and Anucha Apisarnthanarak, MD‡ Key Words: bacteria, misidentification, resource-limited setting, quality improvement (J Patient Saf 2015;00: 00–00)
B
acterial misidentification and misinterpretation of antimicrobial susceptibility test results directly impact patient safety related to inappropriate antibiotic management. Moreover, these problems potentially affect infection control practices such as patient isolation when misidentification involves multidrug-resistant organisms (MDROs).1,2 In Thailand, a highly endemic region of MDRO and carbapenem-resistant Acinetobacter baumannii, accurate microbiological testing is essential to appropriate patient care and good clinical outcomes.3–5 We report misidentification of 7 bacterial isolates during a 1-month period, which was recognized by Infectious Diseases Consultants (IDCs). Infection preventionists (IPs) conducted an investigation and implemented quality improvement (QI) strategies for improving microbiology laboratory workflow and identification protocols.
METHODS Thammasat University Hospital (TUH) is a 650-bed university hospital located in central Thailand. The microbiology laboratory has been operated by 3 technicians and supervised by a technical laboratory supervisor without a doctoral-level clinical microbiologist. The laboratory receives an estimated 3000 specimens for testing per month for bacteriology culture including blood cultures (1500 specimens), respiratory cultures (600 specimens), urine cultures (800 specimens), sterile body fluid cultures (30 specimens), stool cultures (50 specimens), and miscellaneous cultures (50 specimens). The majority of bacterial organisms identified are glucose-nonfermenting gram-negative bacilli (nonfermenters) (300-400 isolates per month) and gram-positive organisms (200-300 isolates per month). Blood cultures are performed using TREK80 media and the VersaTREK system (TREK diagnostics Diagnostics, Oakwood Village, OH). Media for cultures including 5% sheep blood agar (Becton Dickinson, Sparks, MD), MacConkey agar (Becton Dickinson), and Chocolate agar (Oxoid, Ottawa, Canada) were incubated in CO2 and non-CO2 incubators. The bacteriology identification protocol is based on Gram stain interpretation, colony morphology, and conventional biochemical testing. Technicians on service interpret the Gram
From the *Division of Medical Microbiology, Johns Hopkins University School of Medicine; and †Microbiology Laboratory, Johns Hopkins Hospital, Baltimore, MD; and ‡Division of Infectious Diseases, Faculty of Medicine, Thammasat University, Pathumthani, Thailand. Correspondence: Nuntra Suwantarat, MD, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Meyer B1-193 600 N Wolfe St, Baltimore, MD 21287 (e‐mail: [email protected]). The authors disclose no conflict of interest. This study was supported by National Research University Project of the Thailand Office of Higher Education Commission (to A.A. and T.K.) Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Patient Saf • Volume 00, Number 00, Month 2015
stains without double checking results with other technicians and report a Gram stain result directly to primary providers by telephone and in the electronic medical record. Then, antimicrobial susceptibility testing (AST) is performed using Clinical Laboratory and Standards Institute guidelines by disk diffusion testing and E-test (bioMerieux, Marcyl'Etoile, France). Quality control is performed for each new lot of media and biochemical reagents. Temperatures of all incubators are measured daily. The VersaTREK system and AST testing quality control are performed weekly on isolates of Staphylococcus aureus (ATCC 25923, ATCC 29213), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), which were provided by the Thai National Institution of Health (NIH). Bacteriology identification proficiency testing was performed quarterly using unknown isolates from the Thai NIH. The TUH microbiology laboratory's proficiency testing performance had been 100% for 2 years. The TUH infectious disease service gets consulted for every patient who presents with fever and suspected infections. In January 2014, IDCs became aware of several cases of inconsistencies between patient clinical disease and microbiology laboratory results. Infection preventionists conducted an investigation to determine the extent of the misidentifications and to identify factors that contributed to the increase in misidentification. The identification procedures of the suspected misidentified isolates were reviewed. Seven suspected misidentified isolates were submitted to the Thai NIH for final confirmation and identification using the Vitek2 system (bioMerieux) and API 20E system (bioMerieux). Subsequently, new QI strategies for bacteriology identification were implemented. The numbers of misidentified isolates after implementation of QI protocols were recorded.
RESULTS Misidentification of 7 bacterial isolates and patient clinical outcomes during a 1-month period are summarized in Table 1. There was no change in laboratory personnel, and no problems with instruments or reagents were detected. The errors were not traced to a single laboratory technician. The frequency of bacterial misidentification was 1.3% (7/550), which was significantly increased from the previous year (0.08% [6/7554], P
