Bacterial vaginosis laboratory findings: Difference between revisions

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{{Bacterial vaginosis}}
{{Bacterial vaginosis}}


==Overview==
Bacterial vaginosis can be diagnosed by the use of clinical criteria ([[Bacterial vaginosis Amsel criteria|Amsel’s Diagnostic Criteria]]) or Gram stain. A Gram stain is considered the gold standard laboratory method for diagnosing bacteria vaginosis.<ref name=CDC_MMWR-2015>Center for Disease Control and prevention. Mortality and morbidity weekly reports. Sexually transmitted disease treatment guideline. (2015)  https://www.cdc.gov/std/tg2015/tg-2015-print.pdf Accessed on October 20, 2016</ref>
==Laboratory Findings==
==Laboratory Findings==
===Electrolyte and Biomarker Studies===
In clinical practice, the diagnosis of bacterial vaginosis is based on the presence of at least three [[Amsel criteria bacterial vaginosis|Amsel criteria]] on laboratory studies.<ref name=CDC_MMWR-2015>Center for Disease Control and prevention. Mortality and morbidity weekly reports. Sexually transmitted disease treatment guideline. (2015)  https://www.cdc.gov/std/tg2015/tg-2015-print.pdf Accessed on October 20, 2016</ref>
Vaginal swabs following [[Speculum (medical)|speculum]] examination will be tested for:
*Whiff test: A small amount of an alkali is added to a [[microscope slide]] that has been swabbed with the discharge—a "fishy" odor is a positive result for bacterial vaginosis.
*Loss of [[acidity]]: A swab of the discharge is put onto [[litmus paper]] to check the acidity. A positive result for bacterial vaginosis would be a pH>4.5 (normally slightly acidic with a [[pH]] of 3.8–4.2).
*Clue cells: [[epithelial]] cells coated with bacteria (under microscopic examination of the discharge)
In research studies, the use of Nugent or Hay/Ison criteria to evaluate a Gram-stained smear of vaginal discharge is the diagnostic standard.


A healthcare professional seeing a woman presenting with questions about vaginal discharge and irritation in the [[vagina]] and [[vulva]] will have several diagnoses in mind to account for it. To find out which of these is the case, a few simple tests are done.  
===Gram Stain===
A Gram stain is considered the gold standard laboratory method for diagnosing bacteria vaginosis. It is used to determine the relative concentration of [[lactobacilli]] ([[Gram-positive|Gram-positive rods]]), [[Gram-negative]] and Gram-variable rods and cocci ([[Gardnerella vaginalis]], [[Prevotella]], [[Porphyromonas]], and peptostreptococci), and curved Gram- negative rods (Mobiluncus) which are characteristic of bacterial vaginosis.Gram staining is usually reserved for research studies and can be used with the Hay/Ison criteria or the Nugent criteria.<ref name=CDC_MMWR-2015>Center for Disease Control and prevention. Mortality and morbidity weekly reports. Sexually transmitted disease treatment guideline. (2015)  https://www.cdc.gov/std/tg2015/tg-2015-print.pdf Accessed on October 20, 2016</ref><ref name="pmid1706728">{{cite journal| author=Nugent RP, Krohn MA, Hillier SL| title=Reliability of diagnosing bacterial vaginosis is improved by a standardized method of gram stain interpretation. | journal=J Clin Microbiol | year= 1991 | volume= 29 | issue= 2 | pages= 297-301 | pmid=1706728 | doi= | pmc=269757 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1706728  }} </ref>


The healthcare provider will carry out a [[Speculum (medical)|speculum]] examination and take some swabs from high in the vagina. These swabs will be tested for:
====Hay/Ison Criteria====
The Hay/Ison criteria are defined as follows: <ref name="GCH2002">{{cite journal | author=Guideline Clearing House | title=2002 national guideline for the management of bacterial vaginosis | http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=3032&nbr=2258 }}</ref><ref name = HayIson>{{Citation | last1 = Ison | first1 = CA | last2 = Hay | first2 = PE | year = 2002 | title = Validation of a simplified grading of Gram stained vaginal smears for use in genitourinary medicine clinics | journal = Sex Transm Infect | volume = 78 | pages = 413–415}}</ref>
{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
! style="background: #4479BA; width: 175px;" | {{fontcolor|#FFF|Grading}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|Definition}}
|-
| style="padding: 5px 5px; background: #DCDCDC;" |Grade 0
 
| style="padding: 5px 5px; background: #F5F5F5;" | No bacteria present
|-
| style="padding: 5px 5px; background: #DCDCDC;" | Grade 1
 
| style="padding: 5px 5px; background: #F5F5F5;" | [[Lactobacillus]] morphotypes predominate
|-
| style="padding: 5px 5px; background: #DCDCDC;" | Garde 2
 
| style="padding: 5px 5px; background: #F5F5F5;" |  Mixed flora with (some [[lactobacilli]], [[gardnerella]],or mobiluncus morphotypes present)
|-
| style="padding: 5px 5px; background: #DCDCDC;" | Garde 3
 
| style="padding: 5px 5px; background: #F5F5F5;" | Predominantly [[gardnerella]] and/or mobiluncus morphotypes (few or absent lactobacilli)
|-
| style="padding: 5px 5px; background: #DCDCDC;" | Garde 4
 
| style="padding: 5px 5px; background: #F5F5F5;" | Gram-positive cocci predominate
|}
 
*Grade 3 is diagnostic
 
====Nugent Criteria====
The standard for research are the Nugent Criteria.<ref name="Nugent1991">{{cite journal |author=Nugent, R. P., M. A. Krohn, and S. L. Hillier | title=Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation | journal=J. Clin. Microbiol | year=1991 | volume=29 | pages=297&ndash;301 }}</ref>


* A characteristic smell—this is called the whiff test. A small amount of an alkali is added to a [[microscope slide]] that has been swabbed with the discharge—a 'fishy' odour is a positive result for bacterial vaginosis.
{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
* Loss of [[acidity]]—the vagina is normally slightly acidic (with a [[pH]] of 3.8–4.2), which helps to control bacteria. A swab of the discharge is put onto [[litmus paper]] to check the acidity. A positive result for bacterial vaginosis would be a pH of over 4.5.
|+'''Average''' per high powered (1000× oil immersion) field. View multiple fields
* 'Clue cells'—so called because they give a clue to the reason behind the discharge. These are [[epithelial]] cells (like skin) that are coated with bacteria. They can be seen under microscopic examination of the discharge.
! style="background: #4479BA; width: 175px;" | {{fontcolor|#FFF|Score}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|0}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|1}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|2}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|3}}
! style="background: #4479BA; width: 400px;" | {{fontcolor|#FFF|4}}
|-
| style="padding: 5px 5px; background: #DCDCDC;" |[[Lactobacillus]] morphotypes


Two positive results in addition to the discharge itself are enough to diagnose BV. If there is no discharge, then all 3 criteria are needed.<ref name = Amsel>{{Citation | last1 = Amsel | first1 = R | last2 = Totten | first2 = PA | last3 = Spiegel | first3 = CA | last4 = Chen| first4 = KC | last5 = Eschenbach | first5 = D | last6 = Holmes| first6 = KK | year = 1983 | title = Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations | journal = Am J Med | volume = 74 | pages = 14–22}}</ref>
| style="padding: 5px 5px; background: #F5F5F5;" |>30


===Diagnostic Criteria===
| style="padding: 5px 5px; background: #F5F5F5;" | 15-30
====Amsel Criteria====


In clinical practice bacterial vaginosis (BV) is diagnosed using the Amsel criteria:<ref name = Amsel>{{Citation | last1 = Amsel | first1 = R| last2 = Totten | first2 = PA | last3 = Spiegel | first3 = CA | last4 = Chen | first4 = KC | last5 = Eschenbach | first5 = D | last6 = Holmes| first6 = KK | year = 1983 | title = Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations | journal = Am J Med | volume = 74 | pages = 14–22}}</ref>
| style="padding: 5px 5px; background: #F5F5F5;" | <14


# Thin, white, yellow, homogeneous discharge
| style="padding: 5px 5px; background: #F5F5F5;" | <1 (this is an average)
# [[Clue cells]] on [[microscopy]]
# [[pH]] of vaginal fluid >4.5
# Release of a fishy odor on adding [[alkali]]—10% [[potassium hydroxide]] (KOH) solution.


At least three of the four criteria should be present for a confirmed diagnosis.<ref name="GCH2002">{{cite journal | author=Guideline Clearing House | title=2002 national guideline for the management of bacterial vaginosis | http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=3032&nbr=2258 }}</ref>
| style="padding: 5px 5px; background: #F5F5F5;" | 0
|-
| style="padding: 5px 5px; background: #DCDCDC;" |[[Gardnerella]]/[[Bacteroides]] morphotypes


====Hay/Ison Criteria====
| style="padding: 5px 5px; background: #F5F5F5;" | 0
An alternative is to use a Gram stained vaginal smear, with the Hay/Ison<ref name = HayIson>{{Citation | last1 = Ison | first1 = CA | last2 = Hay | first2 = PE | year = 2002 | title = Validation of a simplified grading of Gram stained vaginal smears for use in genitourinary medicine clinics | journal = Sex Transm Infect | volume = 78 | pages = 413–415}}</ref> criteria or the Nugent<ref name="Nugent1991">{{cite journal |author=Nugent, R. P., M. A. Krohn, and S. L. Hillier | title=Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation | journal=J. Clin. Microbiol | year=1991 | volume=29 | pages=297&ndash;301 }}</ref> criteria. The Hay/Ison criteria are defined as follows: <ref name="GCH2002">{{cite journal | author=Guideline Clearing House | title=2002 national guideline for the management of bacterial vaginosis | http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=3032&nbr=2258 }}</ref>
 
* Grade 1 (Normal): [[Lactobacillus]] morphotypes predominate.
| style="padding: 5px 5px; background: #F5F5F5;" | <1 (this is an average)
* Grade 2 (Intermediate): Mixed flora with some Lactobacilli present, but Gardnerella or Mobiluncus morphotypes also present.
 
* Grade 3 (Bacterial Vaginosis): Predominantly Gardnerella and/or Mobiluncus morphotypes. Few or absent Lactobacilli. (Hay et al., 1994)
| style="padding: 5px 5px; background: #F5F5F5;" | 1-4
 
| style="padding: 5px 5px; background: #F5F5F5;" | 5-30
 
| style="padding: 5px 5px; background: #F5F5F5;" | >30
|-
| style="padding: 5px 5px; background: #DCDCDC;" |Curved Gram variable rods
 
| style="padding: 5px 5px; background: #F5F5F5;" | 0
 
| style="padding: 5px 5px; background: #F5F5F5;" | <5


What this technique loses in interobserver reliability, it makes up in ease and speed of use.
| style="padding: 5px 5px; background: #F5F5F5;" | >5


====Nugent Criteria====
| style="padding: 5px 5px; background: #F5F5F5;" |  
The standard for research are the Nugent<ref name="Nugent1991">next</ref> Criteria.  In this scale a score of 0-10 is generated from combining three other scores. It is time consuming and requires trained staff but is has high [[Inter-observer reliability|interobserver reliability]]:
* 0–3 is considered negative for BV
* 4–6 is considered intermediate
* 7+ is considered indicative of BV.
At least 10–20 high power (1000× oil immersion) fields are counted and an average determined.


{| class="wikitable"
| style="padding: 5px 5px; background: #F5F5F5;" |  
|  
Lactobacillus morphotypes — '''average''' per high powered (1000× oil immersion) field. View multiple fields.
||
[[Gardnerella]] / [[Bacteroides]] morphotypes — '''average''' per high powered (1000× oil immersion) field. View multiple fields.
  ||
Curved Gram variable rods — '''average''' per high powered (1000× oil immersion) field. View multiple fields (note that this factor is less important — scores of only 0–2 are possible)
|-
|
* Score 0 for >30
* Score 1 for 15–30
* Score 2 for 14
* Score 3 for <1 (this is an average, so results can be >0, yet <1)
* Score 4 for 0
||
* Score 0 for 0
* Score 1 for <1 (this is an average, so results can be >0, yet <1)
* Score 2 for 1–4
* Score 3 for 5–30
* Score 4 for >30
||
* Score 0 for 0
* Score 1 for <5
* Score 2 for 5+
|}
|}


A recent study <ref name="pmid17078859">{{cite journal |author=Gazi H, Degerli K, Kurt O, ''et al'' |title=Use of DNA hybridization test for diagnosing bacterial vaginosis in women with symptoms suggestive of infection |journal=APMIS |volume=114 |issue=11 |pages=784–7 |year=2006|pmid=17078859 |doi=10.1111/j.1600-0463.2006.apm_485.x}}</ref> compared the gram stain using the Nugent criteria and the DNA hybridization test Affirm VPIII in diagnosing BV. The Affirm VPIII test detected Gardnerella in 107 (93.0%) of 115 vaginal specimens positive for BV diagnosed by gram stain. The Affirm VPIII test has a [[sensitivity (tests)|sensitivity]] of 87.7% and [[specificity (tests)|specificity]] of 96% and may be used for the rapid diagnosis of BV in symptomatic women.
In this scale a score of 0-10 is generated from combining three other scores. It is time consuming and requires trained staff but is has high [[Inter-observer reliability|interobserver reliability]]:
* 0–3 is considered negative for bacterial vaginosis
* 4–6 is considered intermediate
* 7+ is considered indicative of bacterial vaginosis
 
===Cytology===
The Papanicolaou smear is not reliable for diagnosis of bacterial vaginosis.<ref name="pmid10819823">{{cite journal| author=Greene JF, Kuehl TJ, Allen SR| title=The papanicolaou smear: inadequate screening test for bacterial vaginosis during pregnancy. | journal=Am J Obstet Gynecol | year= 2000 | volume= 182 | issue= 5 | pages= 1048-9 | pmid=10819823 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10819823  }} </ref>
===Culture===
Vaginal culture has no role in diagnosis of bacterial vaginosis. <ref name=CDC_MMWR-2015>Center for Disease Control and prevention. Mortality and morbidity weekly reports. Sexually transmitted disease treatment guideline. (2015) https://www.cdc.gov/std/tg2015/tg-2015-print.pdf Accessed on October 20, 2016</ref><ref name="pmid27428605">{{cite journal| author=Stockdale CK| title=A Positive Culture Result for Gardnerella Is Not Diagnostic of Bacterial Vaginosis. | journal=J Low Genit Tract Dis | year= 2016 | volume= 20 | issue= 4 | pages= 281-2 | pmid=27428605 | doi=10.1097/LGT.0000000000000237 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27428605  }} </ref>


==References==
==References==
{{reflist|2}}
{{reflist|2}}


 
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Latest revision as of 20:34, 29 July 2020

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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Overview

Bacterial vaginosis can be diagnosed by the use of clinical criteria (Amsel’s Diagnostic Criteria) or Gram stain. A Gram stain is considered the gold standard laboratory method for diagnosing bacteria vaginosis.[1]

Laboratory Findings

In clinical practice, the diagnosis of bacterial vaginosis is based on the presence of at least three Amsel criteria on laboratory studies.[1] Vaginal swabs following speculum examination will be tested for:

  • Whiff test: A small amount of an alkali is added to a microscope slide that has been swabbed with the discharge—a "fishy" odor is a positive result for bacterial vaginosis.
  • Loss of acidity: A swab of the discharge is put onto litmus paper to check the acidity. A positive result for bacterial vaginosis would be a pH>4.5 (normally slightly acidic with a pH of 3.8–4.2).
  • Clue cells: epithelial cells coated with bacteria (under microscopic examination of the discharge)

In research studies, the use of Nugent or Hay/Ison criteria to evaluate a Gram-stained smear of vaginal discharge is the diagnostic standard.

Gram Stain

A Gram stain is considered the gold standard laboratory method for diagnosing bacteria vaginosis. It is used to determine the relative concentration of lactobacilli (Gram-positive rods), Gram-negative and Gram-variable rods and cocci (Gardnerella vaginalis, Prevotella, Porphyromonas, and peptostreptococci), and curved Gram- negative rods (Mobiluncus) which are characteristic of bacterial vaginosis.Gram staining is usually reserved for research studies and can be used with the Hay/Ison criteria or the Nugent criteria.[1][2]

Hay/Ison Criteria

The Hay/Ison criteria are defined as follows: [3][4]

Grading Definition
Grade 0 No bacteria present
Grade 1 Lactobacillus morphotypes predominate
Garde 2 Mixed flora with (some lactobacilli, gardnerella,or mobiluncus morphotypes present)
Garde 3 Predominantly gardnerella and/or mobiluncus morphotypes (few or absent lactobacilli)
Garde 4 Gram-positive cocci predominate
  • Grade 3 is diagnostic

Nugent Criteria

The standard for research are the Nugent Criteria.[5]

Average per high powered (1000× oil immersion) field. View multiple fields
Score 0 1 2 3 4
Lactobacillus morphotypes >30 15-30 <14 <1 (this is an average) 0
Gardnerella/Bacteroides morphotypes 0 <1 (this is an average) 1-4 5-30 >30
Curved Gram variable rods 0 <5 >5

In this scale a score of 0-10 is generated from combining three other scores. It is time consuming and requires trained staff but is has high interobserver reliability:

  • 0–3 is considered negative for bacterial vaginosis
  • 4–6 is considered intermediate
  • 7+ is considered indicative of bacterial vaginosis

Cytology

The Papanicolaou smear is not reliable for diagnosis of bacterial vaginosis.[6]

Culture

Vaginal culture has no role in diagnosis of bacterial vaginosis. [1][7]

References

  1. ↑ 1.0 1.1 1.2 1.3 Center for Disease Control and prevention. Mortality and morbidity weekly reports. Sexually transmitted disease treatment guideline. (2015) https://www.cdc.gov/std/tg2015/tg-2015-print.pdf Accessed on October 20, 2016
  2. ↑ Nugent RP, Krohn MA, Hillier SL (1991). "Reliability of diagnosing bacterial vaginosis is improved by a standardized method of gram stain interpretation". J Clin Microbiol. 29 (2): 297–301. PMC 269757. PMID 1706728.
  3. ↑ Guideline Clearing House. "2002 national guideline for the management of bacterial vaginosis". Unknown parameter |http://www.guideline.gov/summary/summary.aspx?ss= ignored (help)
  4. ↑ Ison, CA; Hay, PE (2002), "Validation of a simplified grading of Gram stained vaginal smears for use in genitourinary medicine clinics", Sex Transm Infect, 78: 413–415
  5. ↑ Nugent, R. P., M. A. Krohn, and S. L. Hillier (1991). "Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation". J. Clin. Microbiol. 29: 297&ndash, 301.
  6. ↑ Greene JF, Kuehl TJ, Allen SR (2000). "The papanicolaou smear: inadequate screening test for bacterial vaginosis during pregnancy". Am J Obstet Gynecol. 182 (5): 1048–9. PMID 10819823.
  7. ↑ Stockdale CK (2016). "A Positive Culture Result for Gardnerella Is Not Diagnostic of Bacterial Vaginosis". J Low Genit Tract Dis. 20 (4): 281–2. doi:10.1097/LGT.0000000000000237. PMID 27428605.

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