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The Journal of Emergency Medicine, Vol. 37, No. 2, pp. 124–126, 2009Copyright © 2009 Elsevier Inc.

Printed in the USA. All rights reserved0736-4679/09 $–see front matter

doi:10.1016/j.jemermed.2007.02.067

OriginalContributions

EVIDENCE AGAINST THE “BOOTY PACK”: TRICHOMONAS NOT ASSOCIATEDWITH GONORRHEA OR CHLAMYDIA

Stephen Wegner, MD, M. Jim Yen, BS, and Michael Witting, MD, MS

Division of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland

Reprint Address: Michael D. Witting, MD, MS, 110 S. Paca Street, Sixth Floor, Suite 200, Baltimore, MD 21201

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Abstract—Many Emergency Physicians armed with aositive Trichomonas wet mount will also treat for Neisseriaonorrhea (GC) and Chlamydia trachomatis (CT). Thistudy estimates the association between Trichomonas mi-roscopy result and a DNA test result for GC or CT. Usingaboratory records from patients who had simultaneousampling for all three infections, we calculated an oddsatio for the association between the Trichomonas resultnd a positive test for either GC or CT. Among 795 eligibleemales, 105 (13%) had Trichomonas, 74 (9%) had CT, and5 (4%) had GC. Whereas CT and GC were stronglyssociated with each other (odds ratio 5.9, 95% confidencenterval 2.8–12.4, p < 0.0001), Trichomonas infection wasnrelated to infection with either GC or CT (odds ratio 1.1,5% confidence interval 0.6–2, p � 0.9). Trichomonas re-ults do not predict results for GC and CT; they should notnfluence the decision to treat for GC and CT. © 2009lsevier Inc.

Keywords—Trichomonas; chlamydia; gonorrhea; sexu-lly transmitted diseases; epidemiology

INTRODUCTION

hlamydia trachomatis (CT), Neisseria gonorrheaGC), and Trichomonas vaginalis are major causes ofexually transmitted diseases in the United States,ith an estimated 2.8 million new cases of CT,18,000 new cases of GC, and 7.4 million new casesf trichomoniasis each year (1). In the 1960s and970s, 33–50% of women with trichomoniasis were

ECEIVED: 26 July 2006; FINAL SUBMISSION RECEIVED: 2 Fe

CCEPTED: 22 February 2007

124

ocumented as also having GC (2,3). More recenttudies have reported rates of 3–25% of concurrent GCr CT infection in women with trichomoniasis (2,4).

The diagnosis of trichomoniasis involves visualiza-ion of motile trichomonads on a saline wet mount ofaginal fluid; results become available during the pa-ient’s visit (5). By contrast, GC and CT are diagnosedn the basis of positive laboratory tests; in many Emer-ency Departments, results are not available until theollowing day (6).

Asymptomatic infection with CT and GC is common,nd untreated infection can lead to severe health conse-uences, including pelvic inflammatory disease, ectopicregnancy, and infertility (7). Due to these potentialequelae, the Centers for Disease Control and Preventionecommends annual screening of high-risk populationsor GC and CT, and clinicians are urged to have a lowhreshold for diagnosing pelvic inflammatory disease andnitiating empiric antibiotic therapy for both organisms7,8).

Many emergency patients have limited access to an-ual check-ups and are at high risk for the sequelae ofsymptomatic GC and CT. Due to this, and the logicalelief that high-risk sexual behavior tends to producenfection with multiple organisms, we have seen manymergency physicians treat for GC and CT when theyave a positive Trichomonas result. This practice—si-ultaneous Emergency Department treatment of all

hree infections—has been locally termed “the bootyack.” The utility of this practice depends on the strength

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Trichomonas Not Associated with Gonorrhea or Chlamydia 125

f association between trichomoniasis and infection withC or CT. If the association is strong, then a strategy of

imultaneous treatment for GC and CT, given a positiverichomonas result, may be a cost-effective preventivetrategy. If the association is weak, then such a strategyould lead to excessive costs and side effects from

reatment. The aim of this study was to estimate thetrength of association between Trichomonas results andNA test results for GC and CT.

METHODS

tudy Design

his was a cross-sectional study to estimate the associ-tion between a wet mount result for Trichomonas and aositive DNA probe for GC or CT.

election of Participants and Setting

e requested laboratory records for all patients treated atn urban academic tertiary care center between January 1nd July 1, 2002 for whom the laboratory received si-ultaneous samples for Trichomonas testing and forNA testing for CT and GC. We excluded males andatients for whom laboratory records were missing re-ults for one or more tests. For patients who were testedn more than 1 day within the sample frame, we keptata from only the first day. The study protocol wasonsidered exempt from review by our institutional re-iew board.

ethods of Measurement

t this hospital’s laboratory, the wet mount test forrichomonas is done by direct microscopy. The test forC and CT is a dual assay using DNA detection, the BDrobeTec™ ET System (Becton, Dickinson and Com-

able 1. Descriptive Data from 795 Emergency Patientswith Simultaneous Testing for Gonorrhea,Chlamydial Infection, and Trichomoniasis

Characteristic Data

ge, years (median, interquartile range) 25, 19-34richomonas prevalence 105/795 (13%)hlamydia prevalence 74/795 (9%)onorrhea prevalence 35/795 (4%)onorrhea or Chlamydia 97/795 (12%)

any, Franklin Lakes, NJ).T

rimary Data Analysis

ur primary interest was to estimate the strength ofssociation between Trichomonas results and resultsrom the GC-CT probe. This association was quantifiedsing an odds ratio with 95% confidence intervals (CI),alculated using Woolf’s method. In one secondary anal-sis, we tested whether the association differed by agesing the Breslow-Day test for interaction, comparinghildren and adolescents (aged 17 years and under) todults (aged 18 years and older). In another secondarynalysis, we estimated test characteristics for the wetrep result to predict a positive GC-CT probe result.onfidence intervals for proportions were calculated us-

ng a normal binomial approximation.For the sake of comparison, we also calculated an

dds ratio and confidence intervals for the associationetween GC and CT in our data set.

RESULTS

f 933 records, 67 were excluded for being from theame patient multiple times, 70 were excluded for one orore missing test results, and six were excluded for

eing from males. Descriptive data from the remaining95 females are presented in Table 1. The patientsanged in age from 2 to 86 years.

Table 2 shows the distribution of the results ofrichomonas tests vs. DNA tests for GC and CT. Thedds ratio for this association was 1.1 (95% CI 0.6–2, p

0.9), which was not statistically significant. Stratifyingy age � 17 years did not substantially change theesults; there was no evidence of interaction by age (p �.9, Breslow-Day test). By contrast, the odds ratio for thessociation between GC and CT was 5.9 (95% CI 2.8–2.4, p � 0.0001).

Due to the weak association between the Trichomonasest and the GC/CT test, Trichomonas infection had poorest characteristics for GC or CT (with 95% CI): sensi-ivity, 14% (8–23%); specificity, 87% (84–89%); posi-ive predictive value, 13% (8–22%); negative predictivealue, 88% (85–90%); likelihood ratio of a positive test,

able 2. Contingency Table for Trichomonas Infection vs.Infection with Either Chlamydia Trachomatis (CT)or N. Gonorrhoeae (GC) in 795 Females

GC or CTpositive

GC and CTnegative Total

richomonas positive 14 91 105richomonas negative 83 607 690

otal 97 698 795

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.1 (0.7–1.9); likelihood ratio of a negative test, 1.00.9–1.1).

DISCUSSION

ecause GC, CT, and trichomoniasis all result from high-isk sexual behavior, it makes sense that they would bessociated with each other. Because Trichomonas resultsre often available on the day of treatment, logic suggestshat they may be useful in predicting whether a patient alsoas GC or CT, particularly if there is a strong associationetween Trichomonas infection and infection with otherathogens. Although studies have indicated a high “coin-ection rate,” ours is one of the first to quantify the statisticalssociation between the tests using an odds ratio. Our oddsatio estimate, 1.1, suggests that Trichomonas infection isot predictive of concurrent GC or CT.

Previous studies have reported that Trichomonas infec-ion often coexists in a patient infected with GC or CT (2,3).abst et al. documented coinfection rates among patientsith trichomoniasis as 33% (17/52) for GC, 15% (8/52) forT, and 40% (21/52) for either (4). Reynolds and Wilsonocumented similar rates: 10% (8/79) for concurrent GCnd 15% (12/79) for concurrent CT (no combined data wereeported) (2). Patients with trichomoniasis in our studyopulation had lower coinfection rates: 9% (10/105) forT, 7.5% (8/105) for GC, and 13% (14/105) for either.

In the past, a high coinfection rate has been inter-reted as evidence for the predictive value of trichomo-iasis as a marker for other sexually transmitted infec-ions (2,3). However, a high coinfection rate could occurven if no statistically significant association exists be-ween two diseases, if the prevalence of both conditionss high enough. A better way to describe a statisticalssociation between two conditions is to use an oddsatio. An odds ratio of 1 indicates that one condition hasothing to do with the other; that is, they are statisticallyndependent, like two dice thrown together.

In our study, the odds ratio was only 1.1, indicatinghere was no association between trichomoniasis andither GC or CT. The Pabst study also provided adequateata to calculate odds ratios, being 1.0 for patients ex-osed to a sexually transmitted disease (contacts), 1.5 foron-contacts, and 1.4 for both groups combined (4).hite et al. reported a strong negative association (odds

atio � 0.34) between Trichomonas infection and co-nfection with Chlamydia or N. gonorrhoeae (9). In theiratient population, the odds of the presence of GC or CTas three times less when Trichomonas was present,

mplying that Trichomonas is actually protective againsthese other infections (9). Compared with our study, theatients in the White study had a much higher prevalence

f Trichomonas, and a different test was used for diag-

osing GC (9). It is not clear which study demonstrateshe true association between these infections; however,hese studies each offer evidence against the notion thatrichomoniasis indicates infection with GC or CT.

Our findings, and those of White et al., imply thatrichomonas interacts with GC and CT (9). Becauseigh-risk behavior is the overwhelming risk factor for allhree infections, one expects the infections to be posi-ively associated with each other in the absence of anynteraction. For example, GC and CT were stronglyssociated with one another in our study. Interestingly,here has been biological evidence that Trichomonasay be protective against GC and CT. Street et al.

emonstrated in vitro that GC is ingested and killed byrichomonads after 6 h and that CT is eliminated 24 hfter being mixed with Trichomonas (10).

This study has two significant limitations. First, clinicalresentations of patients were not included in our analysis.hat information would be useful for describing the studyopulation and allowing physicians to decide whether ouresults can be generalized to their patient population. Sec-nd, determination of the presence of GC, CT, andrichomonas was limited by the test characteristics of DNA

esting and microscopy for these organisms.In summary, although Trichomonas has traditionally

een regarded as a useful marker for GC and CT, weound no relationship between Trichomonas infectionnd infection with GC or CT. Infection with Trichomo-as, by itself, should not form the basis for simultaneousreatment for GC or CT.

REFERENCES

1. Weinstock H, Berman S, Cates W. Sexually transmitted diseaseamong American youth: incidence and prevalence estimates, 2000.Perspect Sex Reprod Health 2004;36:6–10.

2. Reynolds M, Wilson J. Is Trichomonas vaginalis still a marker forother sexually transmitted infections in women? Int J STD AIDS1996;7:131–2.

3. Tsao W. Trichomoniasis and gonorrhea. Br Med J 1969;1:642–3.4. Pabst K, Reichart C, Knud-Hansen C, et al. Disease prevalence

among women attending a sexually transmitted disease clinic var-ies with reason for visit. Sex Transm Dis 1992;19:88–91.

5. Schwebke J, Burgess D. Trichomoniasis. Clin Microbiol Rev2004;17:794–803.

6. Johnson R, Newhall W, Papp J, et al. Screening tests to detectChlamydia trachomatis and Neisseria gonorrhoeae infections.MMWR Recomm Rep 2002;51:1–38.

7. Centers for Disease Control and Prevention. Sexually transmitteddiseases treatment guidelines 2002. MMWR Recomm Rep 2002;51:32–52.

8. Peipert J. Genital chlamydial infections. N Engl J Med 2003;349:2424–30.

9. White M, Sadalla J, Springer S, Counselman F. Is the presence ofTrichomonas vaginalis a reliable predictor of coinfection withChlamydia trachomatis and/or Neisseria gonorrhoeae in female EDpatients? Am J Emerg Med 2005;23:127–30.

0. Street D, Wells C, Taylor-Robinson D, Ackers J. Interaction between

Trichomonas vaginalis and other pathogenic micro-organisms of thehuman genital tract. Br J Vener Dis 1984;60:31–8.