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## Complete Summary

#### GUIDELINE TITLE

Chlamydia trachomatis. In: Sexually transmitted infections: UK national
screening and testing guidelines.

#### BIBLIOGRAPHIC SOURCE(S)

Carder C, Mercey D, Benn P. Chlamydia trachomatis. In: Ross J, Ison C,
Carder C, Lewis D, Mercey D, Young H. Sexually transmitted infections:
UK national screening and testing guidelines. London (UK): British
Association for Sexual Health and HIV (BASHH); 2006 Aug. p. 26-32. \[9
references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

### COMPLETE SUMMARY CONTENT

 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

*Chlamydia trachomatis* infection

#### GUIDELINE CATEGORY

Diagnosis\
Evaluation\
Screening

#### CLINICAL SPECIALTY

Family Practice\
Infectious Diseases\
Internal Medicine\
Obstetrics and Gynecology\
Urology

#### INTENDED USERS

Advanced Practice Nurses\
Clinical Laboratory Personnel\
Nurses\
Physician Assistants\
Physicians\
Public Health Departments

#### GUIDELINE OBJECTIVE(S)

-   To provide advice on what tests for *Chlamydia trachomatis* are most
    appropriate in a United Kingdom genitourinary (GU) clinic setting
    (excluding human immunodeficiency virus \[HIV\]-infected patients)

-   To provide a basis for audit

-   To support clinics when bidding for additional resources to meet
    national standards

#### TARGET POPULATION

Individuals in the United Kingdom with or at risk for *Chlamydia
trachomatis* infection

#### INTERVENTIONS AND PRACTICES CONSIDERED

1.  Nucleic acid amplifications tests (NAATs) (first choice test for
    urethral, cervical, and first catch urine specimens)

2.  Tissue culture (TC)

3.  Direct fluorescent antibody (DFA)

4.  Enzyme immune assay (EIA)

5.  \"Point of care\"/serological tests/leukocyte esterase tests
    (considered but not recommended)

6.  Sampling according to pack inserts from manufacturer\'s kits from
    the following sites as appropriate: cervix, urethra, pharynx,
    rectum, and vulva/vagina

7.  Special considerations for screening of heterosexual women,
    heterosexual men, homosexual men, young women, young men, pregnant
    women, sexual contacts, sex workers, and victims of sexual assault

8.  Test of cure when appropriate

#### MAJOR OUTCOMES CONSIDERED

Test sensitivity and specificity

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Hand-searches of Published Literature (Secondary Sources)\
Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

A Medline search using the terms *Chlamydia trachomatis*, *diagnosis*,
and *genital* from 1996 to Jan 2004 was conducted, and the most relevant
references are included.

#### NUMBER OF SOURCE DOCUMENTS

Not stated

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

**Levels of Evidence**

**Ia**: Evidence obtained from meta-analysis of randomised controlled
trials

**Ib**: Evidence obtained from at least one randomised controlled trial

**IIa**: Evidence obtained from at least one well designed controlled
study without randomisation

**IIb**: Evidence obtained from at least one other type of well designed
quasi-experimental study

**III**: Evidence obtained from well designed non-experimental
descriptive studies

**IV**: Evidence obtained from expert committee reports or opinions
and/or clinical experience of respected authorities

#### METHODS USED TO ANALYZE THE EVIDENCE

Systematic Review

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

Not stated

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Expert Consensus

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

The guidelines have been developed following the methodological
framework of the Appraisal of Guidelines Research and Evaluation
instrument (AGREE - adapted as described in *Int J STD and AIDS* 2004
15:297-305).

The extent to which the guideline represents the views of intended users
has been addressed primarily by the authorship coming from the
multidisciplinary membership of the Bacterial Special Interest Group
(BSIG). As practising clinicians the authors were able to draw on their
experience of applying the tests to symptomatic and asymptomatic
patients, but it was not feasible to obtain formal input from
representative patients.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

**Grading of Recommendations**

A.  Evidence at level Ia or Ib

B.  Evidence at level IIa, IIb, or III

C.  Evidence at level IV

#### COST ANALYSIS

A formal cost analysis was not performed and published cost analyses
were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

External Peer Review\
Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

After drafting, other health care professionals and professional bodies
in genitourinary (GU) medicine were asked to comment, the draft
guidelines posted on the British Association for Sexual Health and HIV
(BASHH) website for 3 months, and all comments reviewed before final
publication.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

Definitions for the level of evidence (**I-IV**) and grade of
recommendation (**A-C**) are provided at the end of the \"Major
Recommendations\" field.

**[Available Tests]{.underline}**

**Nucleic Acid Amplification Tests (NAATs)**

The role of the nucleic acid amplification technology in the routine
diagnosis of *Chlamydia Trachomatis (C. trachomatis)* infections is
evolving rapidly. Three commercial assays are now available for routine
use:

-   Polymerase chain reaction (PCR; Roche Diagnostics)

-   Strand displacement amplification (SDA; Becton Dickinson)

-   Transcription mediated amplification (TMA; GenProbe)

Although these commercial assays differ in their target sequence and
their method of amplification, it is their ability to produce a positive
signal from theoretically a single copy of the target DNA or RNA (see
pack inserts from the kit manufacturers) that has lead to the reported
increased sensitivity of NAATs. Similar to other nonculture tests, NAATs
do not require viable organisms.

With the advent of molecular diagnostic technology, it is now
appreciated that no single test provides 100% sensitivity and
specificity. Currently, NAATs are proving to be the best tests on the
market. There is no room for complacency, however, as further work is
required to eliminate test problems, such as inhibitors, contamination,
reproducibility, and hormonal factors, that have played a part in
lowering sensitivity.

*Confirming Positive NAATs by Another Technique*

Only another NAAT is sensitive enough to confirm a positive result. This
approach needs further evaluation, as it is rare that individual
laboratories will be able to offer more than one NAAT platform.

*Equivocal Results*

Re-test the original sample (according to manufacturer\'s instructions).

*Inhibition*

Inhibitors can be identified from all sites, in particular first-void
urine. An internal amplification control to identify inhibition should
be used and is available using some of the commercial kits. The
Gen-Probe TMA test has a stage in the extraction process which the
manufacturer claims removes the majority of inhibitors and therefore no
inhibitory control is needed (see individual manufacturer\'s
instructions).

*Pooling Samples*

This is possible and improves cost efficiency but is not licensed.
Optimal pool sizes will vary according to the prevalence in the
population being tested.

**Tissue Culture (TC)**

The traditional method of diagnosing *C. trachomatis* was by cell
culture. However, few laboratories in the United Kingdom (UK) still
offer this service. Cell culture procedures are expensive, labour
intensive and time consuming.

Although chlamydiae are bacteria, they cannot be cultivated in
non-living or cell free media. Tissue culture techniques vary among
laboratories. With no standardised protocol it is difficult to compare
interlaboratory performance. Cell culture detects only viable organisms,
and hence, as with any other bacterial investigation the specimen
collection and transport to the laboratory has to be optimal,
irrespective of which laboratory method is to be used. Even under ideal
conditions the sensitivity is probably no more than 75%, although
specificity should be 100% if a *C. trachomatis*- major outer membrane
protein (MOMP)-specific stain is used.

**Direct Fluorescent Antibody (DFA)**

Specimen material is obtained with a swab or brush, which is then rolled
over the specimen well of a slide. Once air dried and fixed the specimen
can be stained using either a MOMP or lipopolysaccharide (LPS)
fluorescein-labelled monoclonal antibody that binds to *C. trachomatis*
elementary bodies. Stained elementary bodies can then be identified
using a fluorescence microscope. This technique is ideally suited for
small numbers. It can give a quick turnaround time, but its sensitivity
and specificity are dependent on the expertise of the laboratory. DFA
detects both viable and non-viable organisms.

This is the only test allowing simultaneous assessment of specimen
adequacy.

**Enzyme Immuno Assay (EIA)**

There are many commercially available EIA tests on the market for
detecting *C. trachomatis* infection. They detect chlamydial LPS with a
monoclonal or polyclonal antibody that has been labelled with an enzyme.
The enzyme converts a colourless substrate into a coloured product,
which is detected by a spectrophotometer.

As the EIA detects LPS, there is a potential that cross reaction occurs
with other microorganisms causing a false positive reaction, hence it is
vital that confirmation either by DFA or blocking antibody test is
performed.

Sensitivity has been shown to be lower than for NAATs.

**\"Point of Care\"/Serological Tests/Leukocyte Esterase Tests**

As they stand at present, these tests are not advised for diagnosis of
genital *C. trachomatis* in the genitourinary medicine (GUM) setting
(**Grade of Recommendation C**).

**Recommendations**

Because of the superior sensitivity and good specificity of NAATS these
are the tests of choice for urethral, cervical and first catch urine
specimens (**Grade of Recommendation A**).

**[Sites for Testing]{.underline}**

Guidance on how to take samples can be made by following the pack
inserts from the different manufacturer\'s kits.

**First Catch Urine (FCU) --- Grade of Recommendation C**

-   First 15 to 50 mls of urine passed anytime of the day. Patient must
    not have urinated for at least one hour (maybe 2 hours for some
    kits). Follow manufacturer\'s instructions.

-   First catch urine (FCU) is both male and female licensed for most
    NAATs, although less sensitive than from urethral or endocervical
    specimens.

-   Male urine is licensed for some EIAs, shown to be sensitive with
    symptomatic, relatively insensitive for asymptomatic males.

-   Female urine is unsuitable for EIAs.

-   Urine is suitable but not ideal for DFA, needs expertise.

-   Urine is unsuitable for tissue culture techniques.

**Cervical, (Cx)**

Cervical samples are suitable for all tests. Taken under speculum
examination, the swab inserted into the os using the manufacturer\'s
swab collection packs and rotated two or more times for 15 to 30 seconds
(**Grade of Recommendation C**).

**Urethral, (Ur)**

-   Both male and female urethral samples are suitable for all tests.

-   For men the swab is inserted into the urethra 2 to 4 cm and rotated
    one or more times (**Grade of Recommendation C**).

**Pharynx, (Ph)**

-   Pharyngeal samples licensed for tissue culture technique (**Grade of
    Recommendation A**).

-   DFA is licensed for pharyngeal swab specimens but not suitable for
    large throughput use (**Grade of Recommendation C**).

-   Not licensed for most EIAs.

-   NAAT not licensed but increasing work on validation means that for
    any centre without access to culture this is the test of choice
    (**Grade of Recommendation C**).

**Rectal, (Re) (obtained via proctoscopy)**

-   Rectal samples validated for tissue culture technique (**Grade of
    Recommendation A**).

-   DFA is licensed for rectal swab specimens but not suitable for large
    throughput use (**Grade of Recommendation C**).

-   Not licensed for EIA testing owing to the cross reaction with other
    organisms leading to false positive EIA results.

-   Routinely available NAATs for *C. trachomatis* will detect all
    serovars including lymphogranuloma venereum (LGV) serovars and are
    licensed for genital specimens. There are no licensed NAATs for the
    detection of *C. trachomatis* in rectal specimens but data is
    available supporting the validity of these tests for use with rectal
    specimens and therefore for centres without access to culture this
    is the test of choice (**Level of Evidence III, Grade of
    recommendation B**).

**Vulval-Vaginal, (VV)**

Not licensed for use with NAATs, but demonstrated by a number of workers
to produce equivalent sensitivity to cervical testing.

**Table 1: Summary of Recommended Tests for Use with Different Sites of
Samples**

  --------------------------------------------------------------------------
                   **Sites**                                       
  ---------------- ----------- -------- -------- -------- -------- ---------
  **Test**         **FCU**     **Cx**   **Ur**   **Ph**   **Re**   **VV**

  **NAAT**         1           1        1        3        3        3

  **ELISA**        4           2        2        5        5        5

  **DFA**          2           2        2        2        2        5

  **TC**           5           2        2        1        1        5
  --------------------------------------------------------------------------

FCU, first catch urine; Cx, cervix; Ur, urine; Ph, pharynx; Re, rectal;
VV, vulval/vaginal; NAAT, Nucleic Acid Amplification Tests; ELISA,
enzyme-linked immunosorbant assay; DFA, direct fluorescent antibody; TC,
tissue culture

[Key]{.underline}

1.  Test of choice

2.  Acceptable, but not first choice

3.  Not licensed, although encouraging work being performed

4.  Only for use in asymptomatic males

5.  Not recommended

All recommendations are at level B unless stated otherwise.

**[Screening in the Following Patient Groups]{.underline}**

Owing to the frequently asymptomatic nature of genital *C. trachomatis*
there is no difference in the screening guidelines for those showing
symptoms to those who do not.

**[Frequency of Repeat Testing in an Asymptomatic Patient]{.underline}**

This is in part being addressed by the Department of Health (DoH)
Chlamydia Screening Programme. Re-exposure to a possible source of
chlamydia should lead to re-screening if the patient re-presents.

**Heterosexual Women**

Cervical or vulval-vaginal (clinician or self taken) or first catch
urine (**Grade of Recommendation A**)

**Heterosexual Men**

Urethral or first catch urine (**Grade of Recommendation A**)

**Homosexual Men**

Urethral or first catch urine (**Grade of Recommendation A**)

**Young Women**

-   Offer non-invasive tests if speculum examination is declined

-   Vulval-vaginal (clinician or self-taken) or first catch urine
    (**Grade of Recommendation A**)

**Young Men**

-   Offer non-invasive testing if urethral specimen is declined

-   First catch urine (**Grade of Recommendation A**)

**Pregnant Women**

As for heterosexual women. See notes below on test of cure (TOC).

**Contacts**

No different advice

**Sex Workers**

No different advice

**Sexual Assault Victims**

Culture was the recommended method for detecting *C. trachomatis* at all
exposed sites following sexual assault in adults because of 100%
specificity (**Grade of Recommendation C**). This guideline recommends
that a NAAT be taken from all exposed sites in addition to a chlamydial
culture (if culture is available) owing to the low sensitivity of
culture and lack of availability.

**[Test of Cure (TOC)]{.underline}**

Test of cure is not routinely recommended if standard treatment has been
given, there is confirmation that the patient has adhered to therapy and
there is no risk of re-infection. However, if these criteria cannot be
met or if the patient is pregnant a TOC is advised. This should be taken
using the same technique as used for the initial testing. Ideally, a
minimum of 3 to 5 weeks post treatment is required as NAATs will
demonstrate residual DNA/RNA even after successful treatment of the
organism (**Grade of Recommendation A**).

**[Definitions]{.underline}**:

**Levels of Evidence**

**Ia**: Evidence obtained from meta-analysis of randomised controlled
trials

**Ib**: Evidence obtained from at least one randomised controlled trial

**IIa**: Evidence obtained from at least one well designed controlled
study without randomisation

**IIb**: Evidence obtained from at least one other type of well designed
quasi-experimental study

**III**: Evidence obtained from well designed non-experimental
descriptive studies

**IV**: Evidence obtained from expert committee reports or opinions
and/or clinical experience of respected authorities

**Grading of Recommendations**

A.  Evidence at level Ia or Ib

B.  Evidence at level IIa, IIb, or III

C.  Evidence at level IV

#### CLINICAL ALGORITHM(S)

None provided

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The type of supporting evidence is identified and graded for selected
recommendations (see \"Major Recommendations\").

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Accurate diagnosis of *Chlamydia trachomatis* infection

#### POTENTIAL HARMS

Not stated

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

The availability of different microbiology tests may vary and use of
optimal tests as outlined in this guideline may have resource
implications.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Audit Criteria/Indicators

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Getting Better\
Staying Healthy

#### IOM DOMAIN

Effectiveness\
Patient-centeredness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Carder C, Mercey D, Benn P. Chlamydia trachomatis. In: Ross J, Ison C,
Carder C, Lewis D, Mercey D, Young H. Sexually transmitted infections:
UK national screening and testing guidelines. London (UK): British
Association for Sexual Health and HIV (BASHH); 2006 Aug. p. 26-32. \[9
references\]

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

2006 Aug

#### GUIDELINE DEVELOPER(S)

British Association for Sexual Health and HIV - Medical Specialty
Society

#### SOURCE(S) OF FUNDING

No specific or external funding was sought or provided in the
development of this guideline.

#### GUIDELINE COMMITTEE

Screening Guidelines Steering Committee\
Clinical Effectiveness Group (CEG)

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*Authors*: Caroline Carder, University College, London Hospitals Trust;
Danielle Mercey, UCL; Paul Benn, Camden, PCT

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Caroline Carder has been funded to attend conferences by various
diagnostic companies.

Danielle Mercey: None declared

Paul Benn: None declared

#### GUIDELINE STATUS

This is the current release of the guideline.

#### GUIDELINE AVAILABILITY

Electronic copies: Available in Portable Document Format (PDF) from
[British Association for Sexual Health and HIV Web
Site](http://www.bashh.org/documents/59/59.pdf).

#### AVAILABILITY OF COMPANION DOCUMENTS

The following is available:

-   Specifications for the development of UK guidelines on the
    management of sexually transmitted infections (STIs) and closely
    related conditions 2005. London (UK): British Association of Sexual
    Health and HIV (BASHH); 2005. 14 p. Electronic copies: Available in
    Portable Document Format (PDF) from the [British Association for
    Sexual Health and HIV Web
    site](http://www.bashh.org/documents/25/25.pdf).

Additionally, auditable outcome measures can be found in the [original
guideline document](http://www.bashh.org/documents/59/59.pdf).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This NGC summary was completed by ECRI Institute on June 19, 2008. The
information was verified by the guideline developer on October 20, 2008.

#### COPYRIGHT STATEMENT

This NGC summary is based on the original guideline, which is subject to
the guideline developers and/or BMJ Publishing Group\'s copyright
restrictions. Reproduction and use of this guideline is permitted
provided that (a) the original content is not changed or edited; and,
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Readers wishing to download and reproduce material for purposes other
than personal study or education should contact BMJPG to seek permission
first. Contact: BMJ Publishing Group, BMA House, Tavistock Square, WC1H
9JR, UK.

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Date Modified: 11/10/2008