Lab Matters Fall 2017 | Page 19

from the bench

by Michael B . McWilliams , supervisor , Knoxville Regional Laboratory , Tennessee Department of Health Division of Laboratory Services ; George J . Dizikes , PhD , HCLD / CC ( ABB ), director , Knoxville Regional Laboratory , Tennessee Department of Health Division of Laboratory Services ; and Richard S . Steece , PhD , D ( ABMM ), assistant commissioner and laboratory director , Tennessee Department of Health Division of Laboratory Services

In a poster presented at the 2017 APHL Annual Meeting , we described a recent study that examined prevalence of infection by two sexually-transmitted organisms that we believe will become increasingly important in coming years . Both of these organisms , Trichomonas vaginalis ( TV ) and Mycoplasma genitalium ( MG ), were more prevalent than we had initially anticipated , which is of grave concern since they are associated with potential health risks .

Study Parameters

The study was conducted by examining samples from 1,000 women living in eastern Tennessee which had initially come into county public health laboratories with a physician request for chlamydia ( CT ) and gonorrhea ( NG ) screening . We subsequently de-identified and analyzed all of these samples using the Aptima ® TV Assay , a nucleic acid amplification test ( NAAT ) available from Hologic , Inc . While there is no FDA-cleared assay to diagnose MG , our laboratory used analyte specific reagents ( ASRs ) available from Hologic to develop a nucleic acid amplified test to validate for the qualitative detection of MG .

Both tests were run on Hologic ’ s Panther system . Our test was straightforward and resulted in a reliable , accurate test that allowed us to conduct this study . In contrast to the traditional wet-mount tests commonly used in many laboratories for identifying TV , a number of studies 2-7 indicate that NAATs are more sensitive . In addition , we found the Aptima TV assay to be less labor-intensive .

The majority of the samples ( 785 ) were from urine , but 192 were endocervical swabs and 23 were vaginal swabs . The samples were obtained from women ages 20 to 62 , with the majority ( 632 ) from women in the 20-35 age group .

Study Results

We found an overall prevalence of TV and MG to be 7.6 % and 9.7 %, respectively . As has been previously reported , 1 the incidence of TV was highest in the population of women past the age of 35 ( 12.5 %). The reasons for this increase , as well as the potential health implications , remain unknown . Results indicate the highest prevalence of MG ( 11.4 %) in the 20-35 age group . In comparison , we observed an overall prevalence of chlamydia infection of 8.9 %, with the highest rate in women under age 20 ( 11.7 %), and prevalence of gonorrhea of 2.2 %, with highest prevalence ( 2.5 %) in women aged 20-35 .

Rates of co-infection were determined to be 1.2 % for both TV and CT and 1.8 % for both MG and CT . Women with three or more infections were present at less than 1 % for each of the potential combinations examined ( CT + NG + TV ; CT + NG + MG ; CT + TV + MG ; NG + TV + MG ; and CT + NG + TV + MG ).

Implications for TV and MG Prevalence

Infections with multiple sexuallytransmitted organisms have been commonly reported and would be expected given their shared risk factors and the deleterious effects any one of these organisms may have on host defense . What was surprising were the relatively high number of TV and MG infections in these women , which in some age groups rivaled or even surpassed CT prevalence . CT infection is known to have serious adverse health impacts , including pelvic inflammatory disease and infertility . Since the long-term effects of MG are unknown , its prevalence in the population may warrant an investigation of these effects . A secondary problem surrounding MG is that while symptoms can mimic CT , a relatively large number of infections are resistant to CT antibiotics ; it is therefore imperative that the causative agent of infection be identified so as to not exacerbate this resistance . The surprisingly high prevalence of TV , particularly in older women , raises the question of whether or not TV should be considered a reportable disease in the US . n

REFERENCES

1 . Stemmer S , et al . Detection Rates of Trichomonas vaginalis , in Different Age Groups , Using Real-Time Polymerase Chain Reaction . J . Lower Genital Tract Disease . 2012 ; 16 ( 4 ): 352-357 .

2 . Nye M , et al . Comparison of APTIMA Trichomonas vaginalis transcriptionmediated amplification to wet mount microscopy , culture , and polymerase chain reaction for diagnosis of trichomoniasis in men and women . Am J Obstet Gynecol . 2009 ; 200 ( 2 ): 188 . e1-7 . 3

3 . Hobbs , et al . Endocervical and vaginal specimens are comparable for detection of T . vaginalis using transcription mediated amplification ( TMA ). Poster presented at : 18th Meeting of the International Society for Sexually Transmitted Diseases Research ; June 28-July 1 , 2009 ; London , England .

4 . Mamou F et al . Validation of Gen-Probe Aptima Trichomonas vaginalis Analyte Specific Reagent for use in public health clinical laboratories to detect Trichomonas vaginalis in urine sediment . Poster presented at : National STD Prevention Conference ; March 10-13 , 2008 ; Chicago , IL .

5 . Huppert J , et al . Rapid Antigen Testing Compares Favorably with Transcription- Mediated Amplification Assay for the Detection of Trichomonas vaginalis in Young Women . Clin Infect Dis . 2007 ; 45 ( 2 ): 194-8 .

6 . Fuller D . Comparison of Aptima ® Analyte Specific Reagents to Wet Mount , Culture , Affirm VPIII ® and OSOM Trichomonas Rapid Test ® for Detection of Trichomonas vaginalis from Vaginal Swabs and ThinPrep ® Vials . Indiana University School of Medicine . 2007 .

7 . Rich K , et al . Comparison of transcription-mediated amplification , rapid antigen test , culture and wet mount for detection of Trichomonas vaginalis in female adolescents . Poster presented at : 18th Meeting of the International Society for Sexually Transmitted Diseases Research ; June 28-July 1 , 2009 ; London , England . Poster P-137 .