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• Re:Flow cytometry is a sensitive and rapid tool for ruling out NGU
  ALESSANDRO CAMPORESE
  Published on: 7 January 2013
• Re:Sensitivity of Gram stain in urethritis
  Ma Angeles Orellana
  Published on: 2 October 2012
• Sensitivity of Gram stain in urethritis
  David Taylor-Robinson
  Published on: 20 June 2012

• Published on: 7 January 2013

  Re:Flow cytometry is a sensitive and rapid tool for ruling out NGU

  • ALESSANDRO CAMPORESE

  Acute nongonococcal urethritis (NGU) is one of the commonest sexually transmitted infections affecting man and woman. The diagnosis of NGU has traditionally required microscopic evidence of urethritis. However, a significant proportion of patients with urethral symptoms do not have microscopic evidence of urethritis. A recently published article by Orellana MA et al [1] highlighted the low sensitivity of Gram stain in th...

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  Acute nongonococcal urethritis (NGU) is one of the commonest sexually transmitted infections affecting man and woman. The diagnosis of NGU has traditionally required microscopic evidence of urethritis. However, a significant proportion of patients with urethral symptoms do not have microscopic evidence of urethritis. A recently published article by Orellana MA et al [1] highlighted the low sensitivity of Gram stain in the diagnosis of urethritis in men, and the low negative predictive value of microscopic results in symptomatic patients. Whereas, we recently evaluated the analytical performance of the UF-1000i (Sysmex Co, Japan, Supplied by Dasit SpA, Cornaredo, Italy), a recently introduced fluorescence flow cytometer intended for urinalysis purposes [2], which provides new analytical features that seem particularly suitable for microbiological diagnostics, for ruling out NGU or predicting the presence of infection [3]. The Sysmex UF-1000i is a flow cytometry analyzer capable of quantifying a lot of particles, including bacteria and white blood cells (WBCs). To evaluate the analytical performance of the UF-1000i as a method for ruling out NGU, we examined 200 urethral smear samples, collected in a liquid transport medium (Eswab, Copan, Brescia, Italy). We compared the UF-1000i results with microscopic Gram stain, and with results obtained from standard cultures and molecular methods available in our laboratory to detect NGU main pathogens (Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, Ureaplasma parvum, Mycoplasma hominis, Trichomonas vaginalis, Adenovirus, Herpes simplex) . With instrument cut-off values of 200 BACT x10^6/L and 500 WBCs x10^6/L, we obtained a sensitivity of 84%, a specificity of 82%, and a high negative predictive value (96%). Our data demonstrated that Sysmex UF-1000i represents a real tool for ruling out NGU, capable of improving the efficiency of NGU presumptive diagnosis, providing results in a few minutes, with a good value of sensitivity and, above all, a very high negative predictive value.

  References 1. Orellana MA, Gomez-Lus ML, Lora D. Sensitivit? of Gram stain in the diagnosis of urethritis in men. Sex Transm Infect 2012; 88: 284-287. 2. Grosso S, Bruschetta G, Camporese A. Experimental evaluation of the Sysmex UF-1000i for ruling out non-gonococcal urethritis. Infez Med 2012; 20 (3):188-194. 3. De Rosa R, Grosso S, Bruschetta G, et al. Evaluation of the Sysmex UF1000i flow cytometer for ruling out bacterial urinary tract infection. Clin Chim Acta 2010; 411 1137-1142.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
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• Published on: 2 October 2012

  Re:Sensitivity of Gram stain in urethritis

  • Ma Angeles Orellana, Adjunto

  We will try to answer the questions reported by Doctors Taylor- Robinson and Horner. i) This study was carried out in a Primary Care Laboratory, not in a Sexually Transmitted Infection Clinic. This fact could explain the less percentage of patients with ?5 PMNLs and the difference with other studies (1-3). The mean age of patients analyzed was 34 years old with a range between 16- 76. ii) The symptoms were: pain (17%), di...

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  We will try to answer the questions reported by Doctors Taylor- Robinson and Horner. i) This study was carried out in a Primary Care Laboratory, not in a Sexually Transmitted Infection Clinic. This fact could explain the less percentage of patients with ?5 PMNLs and the difference with other studies (1-3). The mean age of patients analyzed was 34 years old with a range between 16- 76. ii) The symptoms were: pain (17%), discharge (40%), itching (21.5%), dysuria (39.3%) and penile irritation (5.7%). The patients were submitted to the laboratory, by their doctors, with the diagnosis of urethritis; and therefore they were included in the study. When these patients attended to the laboratory, 9.2% of them reported not to have symptoms, but they had risk sexual relationship or infection in partner. iii) We did not include this information because we had lacking of this information in a high percentage of patients. iv) When the samples were collected, the swabs were listed from 1 to 4 and number 1 was used for Gram stain. v) In fact, we used the number of ?5 PMNLs per high-power field in ?5 fields like standard practice (4-5). vi) We found ?5 PMNLs in 62.7% of men with discharge and 2.1% in men without discharge. vii) The study was conducted over two years. For one year and a half, C. trachomatis detection was performed by immunochromatography (ICT) and the last 6 months by PCR. Of the 34 C. trachomatis detected, 4 were by ICT and 30 by PCR. One sample of four by ICT had ?5 PMNLs (25%) and 6 of 30 (20%) by PCR. viii) Really, urethritis is defined by the presence of urethral inflammation and as you expose, C. trachomatis and Ureaplasmas do not always elicit urethral inflammation in men. We decided to use the culture like reference method, because we wanted to asses the role of isolated microorganisms, considered unlikely to be causal agents of urethritis and to compare the number of PMNLs in Gram stain, with the isolation of these microorganisms in culture.

  References

  1. Falk L, Fredlund H, Jensen JS. Symptomatic urethritis is more prevalent in men infected with Mycoplasma genitalium than with Chlamydia trachomatis. Sex Transm Infect 2004; 80 :289-93. 2. Horner PJ, Thomas B, Gilroy CB et al. Do all men attending departments of genitourinary medicine need to be screened for non-gonococcal urethritis? Int J STD AIDS 2002; 13: 667-73. 3. Janier M, Lassau F, Casin I et al. Male urethritis with and without discharge: a clinical and microbiological study. Sex Transm Dis 1995; 22: 244-52. 4. Shahmanesh M. 2007 UK National Guideline on the Management of Nongonococcal Urethritis: updated December 2008. http://www bashh org/guidelines 2008 Available from: URL:http://www.bashh.org/guidelines 5. Shahmanesh M, Moi H, Lassau F, Janier M. 2009 European Guideline on the Management of Male Non-gonococcal Urethritis. Int J STD AIDS 2009; 20 :458-64.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
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• Published on: 20 June 2012

  Sensitivity of Gram stain in urethritis

  • David Taylor-Robinson, Professor
  • Other Contributors:
    • Patrick J Horner

  Over several years we have been interested in urethritis and its possible causes. We are aware that a few subjects whose urethral smears are Gram stain negative are, nevertheless, infected with pathogenic micro-organisms. In view of this, we were interested in the paper by Orellano et al. 1 in which they indicate that this may be a bigger problem than otherwise thought...

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  Over several years we have been interested in urethritis and its possible causes. We are aware that a few subjects whose urethral smears are Gram stain negative are, nevertheless, infected with pathogenic micro-organisms. In view of this, we were interested in the paper by Orellano et al. 1 in which they indicate that this may be a bigger problem than otherwise thought. However, we feel that there are aspects of their findings that deserve comment or questioning, as follows: i) The men examined were more than fifteen years of age, but the range of ages and mean age are not mentioned. The fact that only 70 (14%) of 491 symptomatic men had 5 or more PMNLs suggests an unusual population 2-4 ; ii) Samples of urethral exudate were taken from all men with urethral symptoms, which are not described. Was no man asymptomatic and referred as a contact for a "check-up" ? ; iii) The duration of symptoms and any antibiotic use before examination are not mentioned; iv) Of the four urethral swabs, was the first always used for making a smear for staining? ; v) The Gram stain results are recorded as the number of PMNLs per high-power field , but is this a single field or 5 fields, which is standard practice? 5,6 ; vi) Gram staining was performed for all men with or without a discharge, yet no mention is made of whether more PMNLs were found in men with a discharge than in those without 2-4,7; vii) In the first six months of the study the test for detecting Chlamydia trachomatis was less sensitive than the test used in the second six months. What impact did this have on the relationship between C. trachomatis and the Gram stain results ?viii) The sensitivity of the Gram stain as a means of determining the existence of urethritis was assessed (Table 2) ; this was done by comparing the Gram stain results with a reference method, the latter being detection of the various micro-organisms. The rationale of this approach needs explanation since urethritis is not defined by micro-organisms that might cause it but by the presence of urethral inflammation. It is well recognized that Chlamydia trachomatis and ureaplasmas do not always elicit urethral inflammation in men 2,3,5,6,8.

  REFERENCES

  (1) Orellana MA, Gomez-Lus, Lora D. Sensitivity of Gram stain in the diagnosis of urethritis in men. Sex Transm Infect 2012; 88: 284-7.

  (2) Falk L, Fredlund H, Jensen JS. Symptomatic urethritis is more prevalent in men infected with Mycoplasma genitalium than with Chlamydia trachomatis. Sex Transm Infect 2004; 80 :289-93.

  (3) Horner PJ, Thomas B, Gilroy CB et al. Do all men attending departments of genitourinary medicine need to be screened for non-gonococcal urethritis? Int J STD AIDS 2002; 13: 667-73.

  (4) Janier M, Lassau F, Casin I et al. Male urethritis with and without discharge: a clinical and microbiological study. Sex Transm Dis 1995; 22: 244-52.

  (5) Shahmanesh M. 2007 UK National Guideline on the Management of Nongonococcal Urethritis: updated December 2008. http://www bashh org/guidelines 2008 Available from: URL:http://www.bashh.org/guidelines

  (6) Shahmanesh M, Moi H, Lassau F, Janier M. 2009 European Guideline on the Management of Male Non-gonococcal Urethritis. Int J STD AIDS 2009; 20 :458-64.

  (7) Horner P. Asymptomatic men: should they be tested for urethritis? Sex Transm Infect 2007; 83 :81-4.

  (8) Haddow LJ, Bunn A, Copas AJ et al. Polymorph count for predicting non-gonococcal urethral infection: a model using Chlamydia trachomatis diagnosed by ligase chain reaction. Sex Transm Infect 2004; 80 :198-200.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
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