Journal List > Lab Med Online > v.8(1) > 1057378

Kwon, Won, Kee, Kim, Shin, Shin, and Suh: Internal Quality Assurance Status of Stool Examination as Assessed by a Questionnaire in Korean Clinical Laboratories

Abstract

This study aimed to survey the status of quality control (QC) assurance for stool examinations at clinical laboratories in Korea. We sent a questionnaire related to QC practices in stool examination by electronic mail to Korean clinical laboratories that performed stool examination. Overall, 20 of the 39 laboratories (51.3%) reported performing stool concentration methods, and 28 (71.8%) examined the slides using only saline. A large proportion (74.4%) of respondents did not check the internal QC because of the restriction of appropriate control materials. Only four laboratories (10.3%) checked the reactivity of the dye solution routinely. For appropriate external QC systems, QC slides (43.6%) were preferred, followed by QC materials (30.8%), virtual slides (17.9%), and a combination of the above options (7.7%). The most commonly observed parasites in stool samples at the clinical laboratories were Clonorchis sinensis (75%), followed by Endolimax nana, Enterobius vermicularis, and Entamoeba coli. The present study describes the difficulties in internal QC assessment due to the absence of standardized QC materials and systems. We hope the findings of this report will provide a foundation for a QC assessment program for stool examinations in the near future.

REFERENCES

1.World Health Organization. The global burden of disease: 2004 update. Geneva, Switzerland: World Health Organization. 2008.
2.Clinical and Laboratory Standards Institute. Procedures for the recovery and identifcation of parasites from the intestinal tract; approved guideline. 2nd ed.CLSI document M28-A2. Wayne, PA: Clinical and Laboratory Standards Institute;2005.
3.Dovgalev AS., Astanina SY., Malakhov VN., Serdyuk AP., Imamkuliev KD., Gorbunova YP, et al. External quality assessment for the laboratory identifcation of the pathogens of parasitic diseases as an element for improving the postgraduate training of specialists. Med Parazitol (Mosk). 2016. 2:41–4.
4.Chang J., Kim MN., Kim EC., Shin JH., Lee NY., Kim S, et al. Annual report on the external quality assessment scheme for clinical microbiology in Korea (2015). J Lab Med Qual Assur. 2016. 38:169–93.
crossref
5.Manser MM., Saez ACS., Chiodini PL. Faecal parasitology: Concentration methodology needs to be better standardized. PLoS Negl Trop Dis. 2016. 10:e0004579.
6.Verweij JJ., Blangé RA., Templeton K., Schinkel J., Brienen EA., van Rooyen MA, et al. Simultaneous detection of Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum in fecal samples by using multiplex real-time PCR. J Clin Microbiol. 2004. 42:1220–3.
7.Stark D., Al-Qassab SE., Barratt JL., Stanley K., Roberts T., Marriott D, et al. Evaluation of multiplex tandem real-time PCR for detection of Cryp-tosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis in clinical stool samples. J Clin Microbiol. 2011. 49:257–62.
crossref
8.Won EJ., Kim SH., Kee SJ., Shin JH., Suh SP., Chai JY, et al. Multiplex realtime PCR assay targeting eight parasites customized to the Korean population: potential use for detection in diarrheal stool samples from gastroenteritis patients. PLos One. 2016. 11:e0166957.
crossref
9.Gardner BB., Del Junco DJ., Fenn J., Hengesbaugh JH. Comparision of direct wet mount and trichrome staining techniques for detecting Entamoeba species trophozoites in stools. J Clin Microbiol. 1980. 12:656–8.
10.Libman MD., Gyorkos TW., Kokoskin E., Maclean JD. Detection of pathogenic protozoa in the diagnostic laboratory: result reproducibility, specimen pooling, and competency assessment. J Clin Microbiol. 2008. 46:2200–5.
crossref
11.Linder E., Lundin M., Thors C., Lebbad M., Winiecka-Krusnell J., Helin H, et al. Web-based virtual microscopy for parasitology: a novel tool for education and quality assurance. PLoS Negl Trop Dis. 2008. 2:e315.
crossref
12.Weitzel T., Dittrich S., Möhl I., Adusu E., Jelinek T. Evaluation of seven commercial antigen detection tests for Giardia and Cryptosporidium in stool samples. Clin Microbiol Infect. 2006. 12:656–9.
crossref
13.Jahan N., Khatoon R., Ahmad S. A comparison of microscopy and enzyme linked immunosorbent assay for diagnosis of Giardia lamblia in human faecal specimens. J Clin Diagn Res. 2014. 8:DC04–6.
14.Korea Centers for Disease Control and Prevention, Korea Association of Health Promotion. National survey of the prevalence of intestinal parasitic infections in Korea, 2012. The 8th Report. Osong Chungcheon-gbuk-do, Korea, 2013. of Health Promotion. National survey of the prevalence of intestinal.

Fig. 1.
The most commonly observed (A) and the second-most commonly observed (B) parasites during stool examinations in Korean clinical laboratories participating in this study.
lmo-8-19f1.tif
Table 1.
Current status of quality control systems for stool examination in Korea
Items No. (%)
No. of respondents 39
No. of beds in the health care institute  
 >1,000 4 (10.3)
 500–1,000 21 (53.8)
 200–500 7 (17.9)
<200 7 (17.9)
Stool examination method  
 Concentration using formalin-ether or Tween 80 20 (51.3)
 Direct smear only 12 (30.8)
 Cellophane thick smear only 4 (10.3)
 Direct smear and cellophane thick smear 3 (7.7)
Stain used for stool examinations  
 Unnecessary (in the case of cellophane thick smear only) 4 (10.3)
 Saline only 28 (71.8)
 Iodine or trichrome stain 7 (17.9)
Internal quality control system  
 Test patient samples without checking positive/negative controls 29 (74.4)
 Test patient samples after examining negative and positive controls 7 (17.9)
 Test patient samples after examining the positive control 3 (7.7)
Patient samples are tested without control materials due to:  
 Difficulty in obtaining adequate positive/negative control materials 22 (75.9)
 Lack of necessity of internal quality control materials for stool examinations 4 (13.8)
 No answer 3 (10.3)
Reactivity check of the dye solution  
 Do not check 35 (89.7)
 Mix stool and fixation solution 4 (10.3)
Inspection cycle for the reactivity check of the dye solution  
 Do not check/no response 35 (89.7)
 At every test 2 (5.1)
 At least once per month 1 (2.6)
 At least once per week 1 (2.6)
Management of the dye solution  
 Lot-to-lot variation check, Yes 3 (7.7)
 Use of a positive control, Yes 3 (7.7)
Preference of external quality control system for stool examination  
 Quality control slides for stool examination 17 (43.6)
 Positive/negative control materials 12 (30.8)
 Virtual slide photo 7 (17.9)
 Other (combination of the above options) 3 (7.7)
Diagnostic methods used for protozoa  
 Direct smear, cellophane thick smear or formalin-ether concentration without special stains 29 (74.4)
 Special stain after direct smear or formalin-ether concentration 10 (25.6)
Opinion regarding special staining for the diagnosis of protozoan infection  
 Special staining should be performed only if a protozoan infection is suspected 20 (62.5)
 Special staining should be performed for diarrhea specimens, even if a protozoan infection is not suspected 6 (18.8)
 Special staining should be performed for stool examinations in general 3 (9.4)
 Special staining is not necessary for the diagnosis of a protozoan infection 3 (9.4)
Opinion regarding the usefulness of enzyme-linked immunosorbent assays for the diagnosis of Cryptosporidium parvum, Giardia lamblia, and Entamoeba histolytica infections
 Useful for more sensitive and economical diagnosis 30 (81.1)
 Unnecessary 7 (18.9)
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