A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Evaluation of the Serodia Treponema pallidum particle agglutination, the Murex Syphilis ICE and the Enzywell TP tests for serodiagnosis of syphilis

We evaluated the Treponema pallidum haemagglutination assay (TPHA), a treponemal test, with three other treponemal tests, the Serodia T. pallidum particle agglutination assay, the Murex Syphilis ICE IgG + IgM enzyme immunoassay (EIA) and the Enzywell TP IgG + M EIA (a new rapid EIA) for use in conjunction with the rapid plasma reagin test (RPR), a non-treponemal test, for serodiagnosis of syphilis. In all, 124 serum samples were found reactive with RPR and/or TPHA after testing by the routine laboratory protocol. Twenty-three (18.5%) of them were positive only by RPR test and were evaluated as biologically false-positive, 16 were positive only by the TPHA and 84 by both the RPR and TPHA tests; one sample was non-specific (heterophile reaction) in the TPHA.

Agreements of the TPHA with the Serodia TPPA, the Murex Syphilis ICE and the Enzywell TP tests were 96.7%, 100% and 99.1%, respectively.

We conclude that each one of the tests, the Serodia TPPA, the Murex Syphilis ICE and the Enzywell TP, is an appropriate substitute for screening for serodiagnosis of syphilis.

Increased ciprofloxacin resistance in gonococci isolated in Scotland

A review of the susceptibility of Neisseria gonorrhoeae isolated from 4415 episodes of infection in Scotland between 1991 and 1999 showed that the proportion of isolates with lowered susceptibility (ciprofloxacin minimum inhibitory concentration [MIC] > or = 0.05 mg/L) increased from 0.5% in 1991 to 5% in 1999 (p<0.001), whereas the proportion of isolates with clinical resistance (ciprofloxacin MIC > or = 1 mg/L) was significantly higher in 1999 than the average for the preceding 4 years (2.2% vs 0.9%; p=0.02). Ciprofloxacin is a recommended treatment for gonococcal infection in the UK but if resistance continues to increase at the present rate it might not be suitable as a first-line treatment of gonorrhoea for much longer.

The sac-4 gene of Neisseria gonorrhoeae and co-existing chlamydial infection

BACKGROUND/OBJECTIVES

Recently, the sac-4 gene in Neisseria gonorrhoeae was postulated to increase the risk of developing mixed gonococcal and chlamydial infection. The aims of this study were to determine the frequency of the sac-4 gene in a larger sample of isolates of different serovars and to assess the prevalence of sac-4 in gonococcal isolates from patients with and without coexisting chlamydial infection.

METHODS

Isolates from 259 episodes of gonorrhoea were tested by a PCR assay for the sac-4 gene. The presence of co-existing chlamydial infection was determined from both laboratory and GUM clinical records.

RESULTS

The overall prevalence of sac-4 was 57.5% (149/259). The prevalence was not the same in all serovars and ranged from 34.9% in serovar 1B2 to 100% in serovar 1B18. Exact logistic regression analysis indicated significant differences in sac-4 prevalence in isolates of different serovars. The prevalence of sac-4 was 69.5% (41/59) in gonococcal isolates from patients with co-existing chlamydial infection compared with 57.9% (62/107) for those without chlamydial infection. Exact logistic regression analysis showed that the slightly increased sac-4 prevalence among chlamydia positive patients (p = 0.2) virtually disappeared when serovar status was taken into account (p > 0.9).

CONCLUSION

The sac-4 gene of the gonococcus does not increase the risk for mixed chlamydial infection.

Enzywell recombinant enzyme immunoassay for the serological diagnosis of syphilis

The aim of this study was to evaluate Enzywell TP, a new rapid enzyme immunoassay (EIA) that uses 2 recombinant Treponema pallidum antigens for the serological diagnosis of syphilis. Specificity was evaluated by screening 1055 unselected bloods requesting serological tests for syphilis in parallel with Enzywell TP and the Syphilis ICE EIA which is our standard screening test for syphilis. Sensitivity was evaluated using a panel of 159 known treponemal sera representing various stages of syphilis and 5 treponemal sera detected on screening. The specificity of Enzywell TP on initial and repeat testing (99.6% and 99.7% respectively) was similar to that of the Syphilis ICE test (99.8% and 99.9% respectively). The sensitivity of Enzywell TP (100%) was similar to that of Syphilis ICE (99.4%): both tests were significantly more sensitive (P=0.01) than the fluorescent antibody absorbed test (94.5%) but not the T. pallidum particle agglutination (TPPA) assay (99.4%). Both Enzywell TP and Syphilis ICE were positive with sera from 16 known HIV-infected patients who had been treated for syphilis many years previously (mean 9.4 years) confirming the value of these tests in excluding previous syphilis in HIV-infected individuals. We conclude that the Enzywell recombinant EIA is simple, rapid, highly sensitive and specific, and is a welcome addition to the range of currently available diagnostic tests for syphilis.

Rectal gonorrhoea in homosexual men: source of infection

The objective of this retrospective study was to determine the possible source of infection in homosexual men with rectal gonorrhoea: the probable source of rectal gonorrhoea was identified in 46/155 cases. Although the urethra was the site of infection in 33 (72%) of these contacts, only pharyngeal gonorrhoea was identified in 9 (20%) men. In 25/26 cases, there was concordance in the auxo/serotypes of Neisseria gonorrhoeae between contacts with urethral gonorrhoea and the index men with rectal gonorrhoea. Eleven out of 12 pharyngeal isolates were of the same auxo/serotype as the index cases. This study supports the hypothesis that rectal gonorrhoea in homosexual men can be acquired from the oropharynx. Because infection at this site is an independent risk factor for acquisition of HIV, screening for rectal and pharyngeal gonorrhoea should be offered to men who have sex with men, even when there is no history of unprotected receptive anal intercourse.

Subtyping of high-level plasmid-mediated tetracycline resistant Neisseria gonorrhoeae isolated in Scotland between 1992 and 1998

Tetracycline resistant Neisseria gonorrhoeae (TRNG) contain a 25.2 MDa TetM plasmid encoding a 68 KDa cytoplasmic protein which confers high-level tetracycline resistance. The aim of this study was to subtype all TRNG isolated in Scotland between 1992 and 1998. Subtyping was performed by a polymerase chain reaction (PCR) assay which characterizes the TetM plasmid as either the Dutch variant (443 base pair product) or the American variant (777 base pair product). Of the 78 TRNG isolates, 35 were the American variant and 43 were the Dutch variant. TRNG were distributed amongst 30 serovar/auxotype classes, the most common being 1A6/NR (11.5%), 1A6/P (14.1%) and 1B4/NR (14.1%). The country where infection was acquired was known for 36 of the 46 TRNG strains isolated between 1996 and 1998. All infections acquired in Asia and South America were the Dutch variant whereas all infections acquired in Africa were the American variant. A penicillinase plasmid was present in 66% (23/35) of the American variant TRNG compared with 51% (22/43) of the Dutch variant: the 3.2 MDa penicillinase plasmid was found in 87% of the American variant TRNG whereas the 4.4 MDa penicillinase plasmid was found in 68% of the Dutch variant TRNG. We conclude that subtyping of TRNG by PCR is a useful tool in studying the epidemiology of gonococcal infection due to plasmid-mediated resistant isolates.

Epidemiology and treatment outcome of infection with antibiotic resistant strains of Neisseria gonorrhoeae in Scotland

Antibiotic resistance in Neisseria gonorrhoeae occurs worldwide and may limit the efficacy of treatment. This study reports the epidemiology and treatment outcome for 125 episodes of infection with antibiotic resistant gonococci diagnosed in Scotland in 1996. Infections with penicillinase producing N. gonorrhoeae (PPNG) and/or high level plasmid mediated tetracycline resistant N. gonorrhoeae (TRNG) and isolates showing reduced susceptibility to ciprofloxacin were more likely to belong to an unusual serovar and have been acquired abroad by heterosexual intercourse than isolates showing chromosomal resistance to penicillin or tetracycline, which were more likely to belong to a common serovar and to have been acquired in the United Kingdom by homosexual intercourse. Among the 88 episodes of infection whose outcome was known initial treatment with an antibiotic to which the isolate was resistant failed in nine out of 16 infections and in three out of the 72 infections treated with an antibiotic to which the organism was sensitive. In the case of high level plasmid mediated resistance, treatment with an inappropriate antibiotic always resulted in failure. Continuous monitoring of treatment outcome is essential to guide clinicians in prescribing the most appropriate antibiotic for individual patients.

PCR testing of genital and urine specimens compared with culture for the diagnosis of chlamydial infection in men and women

Our aim was to determine the number of chlamydial infections detected by Cobas Amplicor CT/NG multiplex polymerase chain reaction (PCR) testing of genital and first-voided urine (FVU) specimens compared with routine culture. Two hundred and eighty-six female and 276 male patients attending the Genito-Urinary Medicine (GUM) Unit at Edinburgh Royal Infirmary were included in the study. Case notes were analysed retrospectively to determine how many infected patients would not have been treated had diagnosis relied on routine culture. Polymerase chain reaction on FVU from women had a sensitivity, specificity, positive and negative predictive value of 91%, 100%, 100% and 99.1%: corresponding values for genital PCR and culture were 96%, 100%, 100%, 99.6% and 65%, 100%, 100%, 96.7% respectively. PCR on FVU from men had a sensitivity, specificity, positive and negative predictive value of 96%, 99.1%, 92.6% and 99.5%: corresponding values for genital PCR and culture were 89%, 99.5%, 95.8%, 98.6% and 48%, 100%, 100%, 94.3% respectively. In both men and women genital PCR and urine PCR were significantly more sensitive than culture. PCR almost doubled the number of patients detected by culture (49 vs 27). Of the 22 cases detected only by PCR 8 would not have received treatment on the basis of clinic treatment policy.

Novel recombinant-antigen enzyme immunoassay for serological diagnosis of syphilis

Enzyme immunoassay (EIA) is an ideal method for screening large numbers of patients for syphilis. We evaluated a novel immune-capture EIA (ICE Syphilis; Murex Diagnostics) that uses three recombinant Treponema pallidum antigens (TpN15, TpN17, and TpN47) and compared the results with those obtained by the native T. pallidum antigen EIA (Captia SelectSyph-G; Centocor) that we currently use for the serodiagnosis of syphilis. Specificity was evaluated by screening 1,184 unselected serum specimens in parallel by the ICE Syphilis and SelectSyph-G assays, while sensitivity was tested with a panel of 101 serum specimens containing antitreponemal antibodies (treated and untreated) from patients with various stages of infection. The specificity of the ICE Syphilis EIA (99.8%) on screening was significantly higher (P < 0.02) than that of the SelectSyph-G EIA (99.2%). The sensitivity of the ICE Syphilis EIA was significantly higher (P < 0.01) than that of the SelectSyph-G EIA on both initial (99 versus 91.4%) and repeat (100 versus 92.4%) testing. The ICE Syphilis EIA was also significantly more sensitive (P < 0.01) than the fluorescent treponemal antibody-abs (92.4%) but not the T. pallidum hemagglutination assay (97.1%). Sera containing antitreponemal antibodies gave a much higher antibody index (absorbance of test serum/kit cutoff) by the ICE Syphilis EIA than by the SelectSyph-G EIA. This combined with the overall high sensitivity makes the ICE Syphilis EIA an ideal test for excluding or detecting treponemal infection in human immunodeficiency virus (HIV)-infected patients. The ICE Syphilis EIA was positive with sera from all 15 HIV-infected patients in the study, whereas sera from 3 HIV-infected patients were negative by the SelectSyph-G EIA. We conclude that the high sensitivity and specificity of the ICE Syphilis EIA and its suitability for automation make it an ideal screening test.

A new recombinant antigen latex agglutination test (Syphilis Fast) for the rapid serological diagnosis of syphilis

We report an assessment of Syphilis Fast, a new latex test that uses a pool of 3 recombinant Treponema pallidum antigens (TpN15, TpN17, and TpN47) for the serodiagnosis of syphilis. Specificity was evaluated by screening 1518 unselected blood specimens in parallel with Syphilis Fast, the Captia SelectSyph-G EIA and the Venereal Disease Research Laboratory (VDRL) cardiolipin antigen test while sensitivity was tested using a panel of 99 treponemal sera (treated and untreated) representing various stages of infection and 15 treponemal sera detected on screening. The specificity of Syphilis Fast on initial testing (99.8%) was significantly higher (P<0.02) than that of Captia SelectSyph-G (99.2%) and the VDRL (99.1%): the specificity of Syphilis Fast remained significantly higher (P<0.02) after repeat testing (respective values 99.9%, 99.5% and 99.4%). There was no difference in the sensitivity of Syphilis Fast and Captia SelectSyph-G on initial (93% vs 92.1%) or repeat (95.6% vs 94.7%) testing: both were significantly more sensitive (P<0.001) than the VDRL (46.5% on initial and 43.9% on repeat testing). The sensitivities of the Treponema pallidum haemagglutination test (TPHA) and FTA-abs were 98.2% and 95.6% respectively. Negative reactions in Syphilis Fast and SelectSyph-G were associated with treated infections and correlated with low TPHA titres (< or = 80). We conclude that Syphilis Fast is a highly specific, simple and fast screening test with a sensitivity comparable to native antigen treponemal tests and that it merits consideration as a front-line screening test.

Failure of Neisseria gonorrhoeae to grow in the ATB NH susceptibility test system

The ATB NH system designed for antibiotic susceptibility testing of Neisseria gonorrhoeae, Neisseria meningitidis and Haemophilus influenzae was evaluated using 94 clinical isolates of gonococci representing a wide variety of serovar/auxotype strains. Using the manufacturer's automated system 55% of the clinical isolates failed to grow, compared with a 33% failure rate for manual processing and visual reading. Growth failure was significantly higher with 1A isolates (73% automated and 69% manual) than with 1B isolates (49% automated and 25% manual). The higher failure rate of 1A isolates correlated with multiple auxotrophy. The inability of the ATB NH system to support the growth of common serovar/auxotypes makes the ATB NH system unsuitable for antibiotic susceptibility testing of N. gonorrhoeae.

Azithromycin and erythromycin resistant Neisseria gonorrhoeae following treatment with azithromycin

A pre-treatment and a 3-week post-treatment isolate of Neisseria gonorrhoeae from a 13-year-old boy treated with azithromycin in a single 1 g oral dose were characterized microbiologically. Both isolates were of the same serovar/auxotype (1B6/non-requiring) and had similar antibiograms apart from erythromycin and azithromycin: the pre- and post-treatment MICs (minimum inhibitory concentrations) were: 1 mg/L and 32 mg/L to erythromycin and 0.125 mg/L and 3 mg/L to azithromycin. The finding that both isolates were 1B6/NR, had similar antibiograms (other than azithromycin and erythromycin), and no other 1B6/NR isolates were resistant to erythromycin supports the view that macrolide resistance developed following treatment. A high overall level of azithromycin susceptibility was confirmed by testing 67 clinical isolates: MIC90 0.5 mg/L (range 0.023-0.75 mg/L). We conclude that the long half-life of azithromycin which is beneficial in treating chlamydial infection may result in increased selective pressure for resistance in gonococci. This report also highlights the importance of antibiotic susceptibility surveillance of gonococci and stresses the need for appropriate treatment of gonococcal infection, particularly when it is prescribed outwith departments of genitourinary medicine.

Non-cultural detection of rectal and pharyngeal gonorrhoea by the Gen-Probe PACE 2 assay

OBJECTIVE

To assess the sensitivity and specificity of the Gen-Probe PACE 2 assay, which uses a chemiluminescent labelled single-stranded DNA probe to detect gonococcal ribosomal RNA (rRNA), for the non-cultural detection of rectal and pharyngeal gonorrhoea in homosexual men.

SUBJECTS

161 homosexual men attending the Department of Genitourinary Medicine, Edinburgh Royal Infirmary during the latter half of 1995 and the first quarter of 1996.

METHODS

Duplicate rectal and pharyngeal swabs were collected for culture on modified New York City (MNYC) medium and detection of gonococcal nucleic acid by the Gen-Probe assay. Repeatedly reactive Gen-Probe specimens from culture negative patients were also tested by the Gen-Probe competition assay (PCA).

RESULTS

Of the 161 patients, 23 (14.3%) gave a positive culture at one or both sites (rectum 10, throat 8, rectum and throat 5) compared with 28 (16.7%) who gave a positive Gen-Probe result at one or both sites (rectum 9, throat 11, rectum and throat 8). After resolution of discrepant results by PCA the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Gen-Probe was 94.1%, 100%, 100% and 99.3% for rectal specimens while the corresponding values for pharyngeal specimens were 86.4%, 100%, 100%, and 97.9%. The sensitivity and NPV of rectal culture were 88.2% and 98.6% while the corresponding values for pharyngeal culture were 59% and 93.9%. Gen-Probe was significantly more sensitive than throat culture (p < 0.05) but not rectal culture (p > 0.2). The average Relative Light Units (RLU) value for the cut-off was 386 (range 351-450) while the average for a positive result was 20306 (range 403-110104): this was, however, significantly higher (p = 0.019) in rectal specimens 31325 (range 1705-110104) than in throat specimens 10447 (range 403-15633).

CONCLUSIONS

Gen-Probe PACE 2 assay is a sensitive and specific method for the detection of rectal and pharyngeal gonorrhoea. As the Gen-Probe assay may detect nucleic acid from non viable gonococci the clinical significance of a probe positive culture negative specimen from a patient without culture evidence of gonorrhoea at another site is uncertain and requires further consideration. Nevertheless a positive result does indicate exposure to infection and could be important in ensuring appropriate partner notification action. If non-cultural methods are used to screen for gonococcal infection cultures should be obtained from patients with positive results in order that the antibiotic susceptibility and molecular epidemiology of the gonococcal population can be monitored.

Determinants of the gonococcal serovar pattern in Edinburgh, Scotland: a multivariate analysis

The geographical and temporal variety of gonococcal serovar patterns are well described but it remains uncertain what characteristics possessed by the organism, or sexual behaviour pattern in the patients, determine the particular serovar pattern in a given area at a given time. This study was designed to assess the relative contribution of various demographic and clinical features of infection to the observed pattern of serovars in Edinburgh between 1990 and 1993. Five hundred and eight isolates were included in a multivariate analysis model to control for potential interactions between variables. Associations were noted between certain serovars and an asymptomatic clinical presentation, method of acquisition and site of infection. Certain physical characteristics of Neisseria gonorrhoeae in conjunction with the sexual behaviour patterns of patients are partially responsible for observed serovar patterns but more detailed analysis requires further sub-classification of serovars using molecular techniques.

An evaluation of pre-poured selective media for the isolation of Neisseria gonorrhoeae

Fourteen commercial media supplied as pre-poured plates were compared with an 'in-house' selective medium for their ability to support the growth of 105 gonococcal isolates (representing a wide variety of serovars encountered in natural infection), 25 meningococcal and 20 Neisseria lactamica isolates, and to inhibit the growth of 71 isolates of non-pathogenic neisseriae and miscellaneous organisms. Only two of the pre-poured plate media and the in-house selective medium yielded growth of duplicate cultures of all 105 gonococcal isolates after incubation for 24 h: one other medium provided growth of all the isolates after incubation for 48 h. The ability of the various media to suppress the growth of the 71 isolates of non-pathogenic neisseriae and miscellaneous organisms ranged from 97.2 to 71.8% of isolates inhibited. Of the four media that enabled growth of all the gonococcal strains, inhibition was 94.4% for the in-house medium, 85.9% and 80.3% for the two media on which all gonococci grew after 24 h and 71.8% for the medium on which all of the gonococci grew after 48 h. Failure of growth of gonococci was associated with: serogroup IA isolates (p<0.001), AHU auxotype (p<0.001) and the presence of vancomycin rather than lincomycin in the selective medium (p < 0.02). The use of 10% blood and a highly nutritious medium based on the original New York City (NYC) or modified New York City (MNYC) formulation were also important in supporting growth of gonococci. One of the main problems in lack of selectivity was a failure to inhibit the growth of yeasts. As effective inhibition of yeasts was obtained with other media containing the same concentration of amphotericin, failure may be due to batch variation of supplement, media preparation, or reduced shelf life of the media. None of the commercially available pre-poured media performed as well as the in-house medium despite the fact that some of the media were prepared to a very similar formula.

Serovar specific immunity to Neisseria gonorrhoeae: does it exist?

OBJECTIVE

To determine whether the host immune response to gonorrhoea provides limited serovar specific protection from reinfection.

SUBJECTS

508 episodes of gonorrhoea diagnosed at a city centre genitourinary medicine clinic including 22 patients with multiple infections over a 4 year period.

METHODS

Patients with recurrent gonococcal infection were analysed with respect to the initial and subsequent serovars isolated.

RESULTS

No significant difference was seen in the prevalence of serovars isolated following a repeat infection compared with those without repeat infections. The site of the initial infection did not appear to influence the subsequent serovar isolated.

CONCLUSION

We found no evidence of serovar specific immunity in our population. It remains possible that populations with a higher prevalence of gonorrhoea and more frequent infections may have a quantitatively greater immune response.

Gonococcal serovar patterns in Glasgow: 1990-1992

Using monoclonal antibodies directed against protein 1 (major outer membrane protein) in the cell wall of Neisseria gonorrhoeae it is possible to serotype the gonococcus into different sub-groups. This study was designed to analyse the distribution of such serovars in Glasgow, Scotland, and report associations between serovars and clinical features of infection. N. gonorrhoeae isolated from all patients with a diagnosis of gonorrhoea attending genitourinary medicine clinics in Glasgow were serotyped between January 1990 and December 1992. The results were then correlated with sexual orientation of patients, penicillin sensitivity, site of infection, location of acquisition of infection and presence of symptoms. Six hundred and four episodes of gonococcal infection were analysed and an association between certain serovars with sexual orientation, penicillin sensitivity and asymptomatic infection was found. No association between serovar type and locality of acquisition of infection was apparent. Although there was a decreasing trend in the incidence of gonorrhoea overall, infections in homosexual men increased over the three-year study period. The associations between serovars and other features of gonococcal infection are discussed. The observed increase in homosexually-acquired infection has implications with regard to the spread of human immunodeficiency virus infection in this area, and suggests that attempts to promote safer sex in this group are failing.

Markers of past syphilis in HIV infection comparing Captia Syphilis G anti-treponemal IgG enzyme immunoassay with other treponemal antigen tests

The sensitivity of the Captia Syphilis G anti-treponemal IgG enzyme immunoassay (EIA-IgG) was compared with the Treponema pallidum haemagglutination assay (TPHA) and the Fluorescent Treponemal Antibody Absorbed (FTA-Abs) test as a marker for past syphilis in 28 HIV-infected and 31 HIV-negative patients with a past history of syphilis. The specificity of EIA-IgG was compared in 89 patients without a history of syphilis who were known to be HIV antibody positive with a control group of 89 patients who had tested HIV negative. In patients with a past history of syphilis each treponemal test (EIA-IgG, TPHA and FTA-Abs) gave a lower sensitivity (82%, 86%, 79%) in the HIV-positive group than in the HIV-negative group (97%) but the difference was significant only in the case of the FTA-Abs test (P < 0.05). In the HIV-positive patients 11% (3/28) were negative in all 3 treponemal tests while 25% (7/28) were negative in at least one treponemal test. In patients without a past history of syphilis the EIA-IgG antibody index in the HIV-positive group (0.436) was significantly higher than in the HIV-negative group (0.378): the specificity, however, was similar in the HIV-positive (100%) and HIV-negative group (99%). We conclude that the Captia Syphilis G anti-treponemal IgG enzyme immunoassay is of similar specificity in HIV-positive and HIV-negative patients and is of similar sensitivity to the TPHA and FTA-Abs as a marker of past syphilis in HIV-infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Temporal changes in the sensitivity of Neisseria gonorrhoeae to penicillin in Edinburgh, Scotland

Increased resistance of Neisseria gonorrhoeae to penicillin has been reported from many centres around the world since the introduction of antibiotic therapy in the 1940s. This study reports the temporal changes in gonococcal penicillin sensitivity over a 3-year period. All patients with a diagnosis of gonorrhoea in the city of Edinburgh, Scotland between 1990 and 1992 were included in the study. Penicillin sensitivity of isolates was analysed in relation to the sex and sexual orientation of the patient and the antibiotic therapy given. Four hundred and twenty-seven new patient episodes of infection occurred of which penicillin sensitivities were available in 426. Eleven episodes of PPNG infection occurred. Chromosomally mediated penicillin resistance did not increase over the study period. No differences were evident in the sensitivity of isolates from homosexual and heterosexual patients. Unlike many other areas the relative resistance of N. gonorrhoeae is not increasing in Edinburgh at present. This may relate to local antibiotic policies combined with intrinsic characteristics of N. gonorrhoeae itself. Unlike previous reports there did not appear to be any increased resistance to penicillin in isolates from gay men.

Storage and repeated recovery of Neisseria gonorrhoeae using cryovials

One hundred gonococcal isolates, representing eight protein IA serovars and 14 protein IB serovars, were stored at -70 degrees C using the Pro-Lab Microbank cryovial storage system. At monthly intervals a bead from each cryovial was removed and cultured on modified New York City medium. The overall recovery rate was 98.6% (2365/2400), the 35 failures representing 13 separate isolates. There was a small but significant decrease in recovery in the last 12 months of the trial (97.8%) compared with the first 12 months (99.8%), which may have been due to a sampling problem rather than a temporal phenomenon. Failures were significantly associated with minor serovars, suggesting that the transmissibility/viability of minor serovars may be lower than that of common serovars and could be a significant factor in the epidemiology of gonococcal infection. We conclude that Pro-Lab Microbank cryovials provide a highly effective and convenient system for storage of Neisseria gonorrhoeae, particularly when multiple retrieval is required, and the system offers many advantages over conventional lyophilisation.

Gonorrhoea in Aberdeen: a serovar analysis

The serotyping of gonococcal isolates has enabled detailed studies of the epidemiology of gonorrhoea in different geographical areas. This study reports the patterns of infection found in 1992 in Aberdeen and relates these to a variety of clinical parameters. 140 cases of gonorrhoea were isolated the majority of which belonged to one strain (lA-2) in contrast to the diversity of strains seen in other Scottish cities. Most isolates were highly sensitive to penicillin and only 3 penicillinase producing strains were found. A low rate of infections in homosexual men is reported again in contrast to the situation seen in other geographically close cities. Compared to the rest of Scotland Aberdeen has a high prevalence of gonorrhoea.

Rapid identification of pathogenic neisserias using the Identicult-Neisseria test

A rapid enzymatic method using chromogenic substrates for the rapid identification of pathogenic neisseria (Identicult-Neisseria, Scott Laboratories Inc., CA, USA) was tested in parallel with the rapid carbohydrate utilization test (RCUT) and the Phadebact Monoclonal GC Test against 198 consecutive clinical isolates of oxidase-positive Gram-negative diplococci (118 Neisseria gonorrhoeae, 76 N. meningitidis and four N. lactamica). On initial testing the Identicult-Neisseria gave a 95% overall concordance (97.5% N. gonorrhoeae, 90.8% N. meningitidis) with the RCUT and Phadebact tests; the corresponding figures after repeat testing were 98% overall concordance (98.3% N. gonorrhoeae, 97.4% N. meningitidis). Two of the three strains of N. gonorrhoeae mis-identified as N. meningitidis on primary testing were also mis-identified on repeat testing. Seven strains of N. meningitidis were mis-identified on initial testing (six as Moraxella catarrhalis and one as N. lactamica) and two on repeat testing (both as Mor. catarrhalis). We conclude that the Identicult-Neisseria is not sufficiently reliable for the culture confirmation of gonococci and meningococci.

Penicillin susceptibility testing of penicillinase producing Neisseria gonorrhoeae by the E test: a need for caution

The penicillin MICs of 52 clinical isolates of penicillinase producing Neisseria gonorrhoeae (PPNG) and five reference strains were tested by agar dilution and the E test. All 52 PPNG were scored resistant (> or = 2 mg/L) by agar dilution whereas only 78.8% (41/52) and 82.7% (43/52) were classified as resistant by normal (0.016-256 mg/L) and low range (0.002-32 mg/L) E test MICs respectively. Isolates with an E test penicillin MIC > or = 0.19 mg/L should be checked by a specific test for beta-lactamase production.

Gonococcal infection in Edinburgh and Newcastle: serovar prevalence in relation to clinical features and sexual orientation

AIMS

The variable distribution of gonococcal serovars in different areas is well recognised but the factors that are important determinants of serovar prevalence are less clear. The aim of this study was to identify relevant clinical variables by comparing serovar prevalence in two cities over the same time period.

METHODS

A prospective analysis of serovar prevalence was made between January and December 1992 in Edinburgh and Newcastle with respect to age, sex, sexual orientation, antibiotic sensitivity and presence of symptoms.

RESULTS

224 infective episodes of gonorrhoea were studied. The serovar distribution varied between the two cities with serovar 1B-1 being more common in Edinburgh (20/91 cf. 4/133, p < 0.01) and serovar 1B-6 more common in Newcastle (26/133 cf. 2/91, p < 0.01). Serovar 1A-2 was associated with heterosexual infection (35/114 in heterosexuals cf. 0/85 in homosexuals, p < 0.01) and was more sensitive to penicillin than average (39/39 1A-2 strains highly penicillin sensitive cf. 98/184 for all other strains, p < 0.01) whilst 1B-6 was mostly acquired through homosexual contact (22/26 cf. 63/142 for all other strains, p < 0.01) and tended to show reduced penicillin susceptibility (13/28 1B-6 strains less penicillin sensitive cf. 45/195 for all other strains, p < 0.01). Infection with serovar 1A-2 was significantly less often symptomatic in heterosexuals than average (15/33 asymptomatic 1A-2 infections cf. 17/59 for all other serovars, p = 0.015). Subgroup analysis of male heterosexual infections confirms an association between asymptomatic infection and serovar 1A-2 (2/14 asymptomatic 1A-2 infections cf. 1/72 for all other serovars, p = 0.02). The distribution of infections over the year differed between the cities.

CONCLUSIONS

A variety of factors including penicillin sensitivity and virulence may be important in determining the prevalence of gonococcal serovars within a given area.

Typing of Neisseria gonorrhoeae by auxotype, serovar and lectin agglutination

A total of 267 strains of Neisseria gonorrhoeae, comprising 129 serogroup IA and 138 serogroup IB, isolated in Edinburgh over a two-year period were analysed to assess the discrimination given by three typing methods: auxotyping; serotyping using the Genetic Systems (GS) and Pharmacia (PH) monoclonal antibody panels; and lectin agglutination. Each typing system was assessed individually and in combination. Serotyping subdivided the strains into 14 GS and 18PH serovars. Auxotyping (Aux) yielded 11 separate auxotypes while lectin agglutination yielded 22 different reaction patterns (LP). The standard auxotype/GS serovar (A/S) classification system yielded 37 classes. Lectin agglutination allowed further subdivision of the main A/S classes. AHU/IA-2 strains,which accounted for 70% of IA strains, yielded nine different lectin patterns (A/S/LP classes). Likewise, lectin agglutination allowed subdivision of the main IB A/S classes. NR/IB-1, NR/IB-2 and NR/IB-3, which accounted for 28%, 38% and 20% respectively of the IB strains, yielded 7, 7 and 6 A/S/LP classes respectively. It was concluded that lectin agglutination is a useful adjunct to the standard A/S classification system for studying the micro-epidemiology of gonococcal infection.

Comparative evaluation of AccuProbe culture identification test for Neisseria gonorrhoeae and other rapid methods

The AccuProbe chemiluminescent culture identification test for Neisseria gonorrhoeae (Gen-Probe Inc., San Diego, Calif.) was assessed in a comparative evaluation with other rapid methods by using 269 isolates of oxidase-positive, gram-negative diplococci. Chemiluminescence was read with a PAL luminometer, and results were expressed as PAL light units (PLUs): the cutoff value for a positive identification was 1,500 PLUs. All 200 isolates of gonococci confirmed by carbohydrate utilization and serotyped with monoclonal antibodies were identified correctly by AccuProbe on initial testing. The API Quadferm system (Bio Merieux, Marcy l'Etoile, France) identified 95% (n = 190) of the gonococci correctly on initial testing and 99.5% (n = 199) on repeat testing, while the Phadebact Monoclonal GC test (Kara Bio Diagnostics AB, Huddinge, Sweden) identified 95.5% (n = 191) of the gonococci on both initial and repeat testing; 8 of the Phadebact-negative isolates were all of the same rare serovar (serovar 1B-17). The mean PLU for the gonococcal isolates was 9,014 (range 2,264 to 10,845) compared with a mean of 51 (range, 8 to 109) for the 69 nongonococcal isolates. We conclude that the AccuProbe culture confirmation test provides a rapid and accurate objective means of identifying cultured N. gonorrhoeae isolates.

Serotype patterns of gonococcal infection in contact pairs

The use of gonococcal serovars in studying the epidemiology of Neisseria gonorrhoeae is well established. Most studies assume that the isolated serovar remains stable in vivo indefinitely. This study was designed to observe the correlation between serovars isolated in patients naming each other as sexual contacts. The overall rate of discordant transmission episodes was 12% (26/220). There were however significantly more discordant transmission episodes for partners of patients infected with IB serovars than IA serovars: 19% (23/124) versus 3% (3/96) - p < 0.01. The overall prevalence of serogroup IB isolates although significantly higher at 53% (p < 0.01) was thought insufficient to account for the correlation between discordant pairs and serogroup IB infection. Reasons considered for the discrepancies in contact pairs included: problems of partner reporting involving inaccurate or incomplete information; technical problems with reagents; culture induced phenotypic variation in antigenic expression or differences in the in vitro recognition of epitopes; and antigenic differences resulting from genetic mutation within the Protein I gene. It was concluded that carefully planned and controlled prospective studies involving duplicate parallel testing of isolates from patients and their well documented partners are needed to assess the extent to which these various factors contribute to discordancies in serovars isolated from contact pairs. Serotyping should be combined with other methods such as auxotyping for detailed microepidemiological studies involving partner notification.

Anogenital non-gonococcal neisseriae: prevalence and clinical significance

Over a 13-year period non-gonococcal neisseriae (NGN) were isolated from 114 of 88,670 patients (0.13%) screened for anogenital gonorrhoea at a Genitourinary Medicine Unit. During the same period there were approximately 9000 anogenital gonococcal infections (10%). The prevalence of NGN was 0.09% (27/31,500) in women, 0.04% (20/52,800) in heterosexual men and 1.5% (67/4370) in homosexual men: the differences in prevalence between women and heterosexual men (P < 0.01) and between heterosexual patients and homosexual men (P < 0.001) are highly significant. Neisseria meningitidis was isolated most frequently and accounted for 85% (99/114) of the NGN. Whenever possible, N. meningitidis was serogrouped and its occurrence correlated with patient symptoms. Eleven of 18 heterosexual men who had meningococci isolated from their urethras had urethritis but co-existing chlamydial infection was excluded in only 5. None of 9 women with cervical colonization had clinical evidence of pelvic inflammation. Only one of 49 men with rectal colonization had proctitis. The management of anogenital NGN infection is discussed in relation to our findings and those of previously published studies. Within each patient group the prevalence and incidence of anogenital NGN were similar at the beginning and end of the study period indicating that levels have not been influenced by the advent of AIDS.

An analysis of lectin agglutination as a means of sub-dividing gonococcal serovars

Sixteen lectins were examined for their ability to agglutinate 298 strains of Neisseria gonorrhoeae. Seven lectins failed to agglutinate any of the strains; the remaining nine lectins gave 22 different agglutination patterns. The 298 strains were divided into 14 serovars with a single panel of monoclonal antibody typing reagents; lectin agglutination subdivided these into 57 serovar/lectin patterns. A combination of two monoclonal antibody serotyping panels divided the strains into 32 serovar combinations; lectin agglutination further subdivided these into 79 serovar/lectin patterns. There was no correlation between lectin pattern and serovar. Lectin agglutination is a simple supplementary typing method and could be particularly useful in micro-epidemiological studies.

Syphilis diagnosis: screening by enzyme immunoassay and variation in fluorescent treponemal antibody absorbed (FTA-ABS) confirmatory test performance

Four fluorescent treponemal antibody absorbed (FTA-ABS) test kits were evaluated with 86 treponemal and 84 non-treponemal sera selected with enzyme immunoassay (EIA). Agreement between all four kits was 63% for treponemal, and 50% for non-treponemal, sera. Discrepancies with treponemal sera were associated with low levels of antibody characterised by T. pallidum haemagglutination assay (TPHA) titres < or = 160 and a negative Venereal Diseases Research Laboratory (VDRL) test. Discrepancies with non-treponemal sera were significantly associated with false reactivity on screening with EIA. Possible reasons for the differences obtained between kits, the importance of screening policies for pre-selecting sera, and the significance of equivocal (borderline) reactions on positive and negative predictive values are discussed.

A serovar analysis of heterosexual gonorrhoea in Edinburgh 1986-90

OBJECTIVE

To analyse the frequency of different gonococcal serovars within Edinburgh, Scotland and to describe changes that occurred in the frequency of such serovars over time.

METHODS

All heterosexual patients with a diagnosis of gonorrhoea confirmed on culture between January 1986 and December 1990 had their gonococcal strain serotyped. Temporal changes in the prevalence of gonorrhoea and the serovar of the isolates were analysed.

RESULTS

Isolates of Neisseria gonorrhoeae from 1356 episodes of gonorrhoea were serotyped. Three serovars, Bajk (IB-3/IB-6), Bacejk (IB-1/IB-2) and Aedgkih (IA-1/IA-2), dominated, occurring in two-thirds of all infections. Over the study period Bajk (IB-3/IB-6) and Aedgkih (IA-1/IA-2) isolates declined in frequency in parallel with an overall fall in the prevalence of gonorrhoea but Bacejk (IB-1/IB-2) persisted at a lower but fairly constant level. Despite a fall in the number of gonococcal infections the variety of new serovars being isolated fluctuated.

CONCLUSIONS

The ability of some serovars to persist while others decline in incidence may be partially related to antibiotic sensitivities but other factors such as an ability to evade the immune response and transfer of serovars from one population group to another may also be important.

Enzyme immunoassay for anti-treponemal IgG: screening or confirmatory test?

AIMS

To review the performance of the Venereal Diseases Research Laboratory (VDRL) test and the Treponema pallidum haemagglutination assay (TPHA) as a combined screen for syphilis to provide a baseline for assessing screening by anti-treponemal IGG EIA.

METHODS

Between 1980 and 1987 all serum samples were screened by both VDRL and TPHA tests. The FTA-ABS test was also used in suspected early primary syphilis, or when one of the other tests was positive. A positive result in a screening test was confirmed by quantitative testing. From 1988 all specimens were screened with an enzyme immunoassay (Captia Syph G) as a single screening test.

RESULTS

Of the 44 primary, 47 secondary, and 38 early latent cases of syphilis, the VDRL and TPHA detected 32 (73%) and 31 (71%) of the primary cases; the combination detected 37 (84%). All 85 cases of cases of secondary and early latent infection were reactive in the TPHA test, whereas the VDRL was reactive in only 68 (80%). EIA had a reported sensitivity of 82% for primary infection.

CONCLUSIONS

EIA can be used as a single screening test for detecting early syphilis because its results are comparable with those of the combined VDRL and TPHA tests. The conventional VDRL test should not be used as a single screening test.

An analysis of false positive reactions occurring with the Captia Syph G EIA

AIM

The Captia Syph G enzyme immuno assay (EAI) offers the potential for the rapid automated detection of syphilis antibodies. This study was designed to assess the role of other sexually transmitted diseases (STDs) in producing false positive reactions in the Captia Syph G EIA. The role of rheumatoid factor (RF) as a potential source of false positives was also analysed.

METHODS

Patients who attended a genitourinary medicine (GUM) department and gave a false positive reaction with the EIA between 1988 and 1990 were compared with women undergoing antenatal testing and with the control clinic population (EIA negative) over the same time period. The incidence of sexually transmitted disease (STD) in the clinic population and the false positive reactors was measured in relation to gonorrhoea, chlamydia, genital warts, candidiasis, "other conditions not requiring treatment" and "other conditions requiring treatment." Male: female sex ratios were also compared. Ninety two RF positive sera were analysed with the EIA.

RESULTS

The rate of false positive reactions did not differ with respect to the diagnosis within the GUM clinic population. The antenatal group of women, however, had a lower incidence of false positive reactions than the GUM clinic group. No RF positive sera were positive on Captia Syph G EIA testing.

CONCLUSIONS

There is no cross reaction between Captia Syph G EIA and any specific STD or with RF positive sera. The lower incidence of false positive reactions in antenatal women is unexplained but may be related to physiological changes associated with pregnancy.

Patterns of homosexually acquired gonococcal serovars in Edinburgh 1986-90

AIM

The aim of this study was to observe the changes in gonococcal serovar pattern in homosexual men over a 5 year period.

METHODS

All men who presented to the Genitourinary Medicine clinic at Edinburgh Royal Infirmary between 1986 and 1990 with homosexually acquired gonococcal infection were included in the study. Gonococcal isolates were serotyped and the temporal change in isolated serovars noted.

RESULTS

Over the 5 year period 32 different serovars were associated with 175 homosexually acquired infections. There was a dynamic temporal change in the dominant serovars with a continual influx of new strains some of which become established in the community but most of which appeared only transiently. Rapid variation in incidence over time was observed for certain serovars while others remained at more constant levels. There was a marked association between certain serovars (Ae/Av; Back/Bropyt; Bacejk/Brpyut; Bacejk/Brpyust; Baejk/Brpyut) and homosexually acquired infection.

CONCLUSIONS

Possible determinants for the patterns observed are discussed but the underlying mechanism is probably multifactorial.

Epidemiological typing of Neisseria gonorrhoeae: a comparative analysis of three monoclonal antibody serotyping panels

Sixteen hundred and thirty seven isolates of Neisseria gonorrhoeae isolated over a two year period were serotyped using three panels of monoclonal antibodies. The isolates comprised 687 serogroup WI strains and 950 serogroup WII/III strains. The antibodies used in the panels were those developed by Pharmacia (Ph) and Genetic Systems (GS). The GS antibodies were used as two separate panels; the American (GS-A) panel which designates serovars by a simple numerical nomenclature and the Swedish (GS-S) panel which designates serovars by a more detailed descriptive nomenclature. Using only a single panel the Ph panel gave the greatest discrimination yielding 42 serovars compared with 28 serovars with the GS-S panel and 23 serovars with the GS-A panel. Using two panels in combination, the GS-A/Ph panel combination gave the greatest discrimination with 81 serovar combinations while a combination of the GS-S and Ph panels yielded 77 serovar combinations. A compilation of antibodies from all three panels yielded 90 serovar combinations. As the combination of GS-A and Ph panels gave a greater degree of discrimination than the combination of the GS-S and Ph panels we advocate that first-stage serotyping should be performed with the more widely used GS-A panel while second-stage serotyping should be performed with the Ph panel. We propose that serovar combinations should be reported using a dual nomenclature e.g. IA-1/Arost, IB-1/Bropt, IB-1/Bropyt etc. The use of such a dual system would allow "core comparison" between all centres while maintaining a degree of flexibility regarding the extent of discrimination required.

Preliminary evaluation of "Clearview Chlamydia" for the rapid detection of chlamydial antigen in cervical secretions

Clearview Chlamydia (Unipath) is a rapid monoclonal antibody based latex immunodiffusion test for detecting chlamydial antigen in endocervical specimens. The assay does not require specialised equipment or extensive training and takes less than 30 minutes from sample to results. The clinical performance of Clearview Chlamydia was evaluated with 478 paired endocervical swabs from patients attending a genitourinary medicine clinic. In the first part of the study, 221 non-randomised specimens were tested by cell culture (1st swab) and Clearview (2nd swab) whereas in the second part of the study 257 randomised swabs were examined by Clearview, cell culture and immunofluorescence. The overall prevalence of chlamydial infection was 8.8% and the sensitivity, specificity, positive and negative predictive values for Clearview were 85.7%, 99.1%, 90% and 98.6%. The test requires further evaluation to establish its role in the management and control of chlamydial infection.

Is coexisting chlamydial infection more common in gonococcal infections with serogroup WI?

Over a 4-year period a total of 8974 women were screened for Neisseria gonorrhoeae and Chlamydia trachomatis. There were 489 cases of cervical gonorrhoea, 261 serogroup WI and 228 serogroup WII/III. A total of 169 (34.6%) cases had a dual infection with C. trachomatis, 92 from the WI serogroup and 77 from the WII/III. Using Fisher's exact test, no statistically significant difference was observed in the rates of chlamydial carriage between the two serogroups (P = 0.39). These findings are at odds with previously reported data, which suggested a biological interaction resulting in a positive correlation between colonization with serogroup WI and C. trachomatis. Possible reasons for the difference between the findings are discussed.

Gonococcal infection within Scotland: antigenic heterogeneity and antibiotic susceptibility of infecting strains

Two panels of monoclonal antibody reagents were used to serotype all strains of Neisseria gonorrhoeae isolated from four separate geographical areas serving two million of the five million Scottish population. Serotype 1B isolates accounted for 60% of the 869 strains examined and were more prevalent than 1A isolates in each geographical area. A total of 11 1A serovars and 47 1B serovars were recognised. Only two of the 11 1A serovars (Aedgkih/Arost and Aedih/Arst) were found in every centre but these accounted for over 90% of the 1A isolates. Although there was a total of 47 different 1B serovars over 80% of the isolates were accounted for by the ten most commonly encountered serovars. There were, however, marked geographical differences within both major and minor serovars. There was a highly significant difference (P less than 0.001) between protein 1A and 1B serovars with respect to their susceptibility to penicillin. Within each protein 1 type there were also differences in antibiotic susceptibility. Penicillinase-producing N. gonorrhoeae (PPNG) were found in all centres and accounted for 24 (2.8%) of the 869 isolates. The majority of the PPNG (71%) were serotype 1A and with one exception were serovar Aedih/Arst. PPNG strains accounted for 37% (16) of the 43 Aedih/Arst isolates. Epidemiological, diagnostic and therapeutic implications arising from the distinct geographical differences in the pool of circulating gonococci are discussed.

Screening for treponemal infection by a new enzyme immunoassay

A new enzyme immunoassay (EIA, Captia Syphilis-G) for detecting IgG antibodies against Treponema pallidum was evaluated as a screening test for syphilis. When serum samples were tested at a dilution of 1 in 20 (EIA20), the overall agreement between the IgG EIA and serological status based on the T pallidum haemagglutination assay (TPHA) and the fluorescent treponemal antibody absorption (FTA-ABS) test was 99.2% (1310/1321). The sensitivity of the EIA20 was 98.4% (60/61) and the specificity 99.3% (1251/1260). Discrimination between patients with and without treponemal infection was good: the mean EIA20 absorbance ratios (patient/mean low titre positive control results) were 0.49 for antibody negative patients, 3.30 for patients with positive Venereal Diseases Research Laboratory (VDRL) test and TPHA results, and 1.77 for patients with negative VDRL but positive TPHA results. The cut off point for excluding treponemal infection was taken as 0.9. Specimens with ratios of more than 0.9 should be confirmed by the FTA-ABS test and evaluated for specific IgM antibodies to treponemes. When serum samples were tested at a 1 in 50 dilution (EIA50) the sensitivity was lower (80.3%) but the specificity was absolute. The reduction in sensitivity correlated with low absorbance ratios in the patients who were VDRL negative and TPHA positive. The screening performance of the IgG EIA20 is thus comparable with that provided by a combination of the VDRL test and TPHA. The potential for automation makes the EIA an attractive alternative, particularly in larger centres. Alternatively, the test can be performed at a 1 in 50 dilution (EIA50), at which level it is ideally suited for confirming the treponemal status of antibodies in serum samples preselected by positive cardiolipin antigen screening test results.

Utility of monoclonal antibody coagglutination to identify Neisseria gonorrhoeae

The Phadebact monoclonal gonococcus coagglutination test was evaluated with 1367 (996 anogenital and 371 pharyngeal) neisserial isolates from patients who gave positive diagnostic test results for Neisseria gonorrhoeae. The overall correlation with carbohydrate utilisation was 99.7%. The Phadebact test had a specificity of 100% (286/286) and a sensitivity of 99.7% (1077/1080). The three non-reactive strains were epidemiologically linked and were of a very unusual serovar. Unlike polyclonal antibody based tests, the monoclonal antibody test provides reliable identification of gonococci from anogenital and pharyngeal sites. Because non-reactive strains are rare, however, negative anogenital isolates from heterosexual patients should be tested biochemically. The use of two reagents comprising separate pools of monoclonal antibodies against gonococcal protein IA and IB permitted the identification of an appreciable number of double infections, which would otherwise have been missed. Genital, rectal, and pharyngeal isolates from the same patient should be identified individually.

Fluorescent monoclonal antibody test for the confirmation of Neisseria gonorrhoeae

The Microtrak fluorescein labelled monoclonal antibody test for the culture confirmation of Neisseria gonorrhoeae was evaluated with 157 clinical isolates of oxidase-positive Gram-negative diplococci, including 110 strains of N. gonorrhoeae. Seventy-eight stock cultures of neisseria were tested to confirm the results from clinical samples. The test gave a specificity of 100% and sensitivity of 98%. Only four strains of the rare serovar Behj were non-reactive. As the prevalence of this serovar influences the utility of the test, the rarity of this serovar in different geographical locations is discussed.