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Lymphogranuloma venereum in the United kingdom.

BACKGROUND Over the past 2 years, lymphogranuloma venereum (LGV), caused by L serovars of Chlamydia trachomatis, has emerged as a significant problem among men who have sex with men (MSM). We report on, to our knowledge, the largest case series of LGV to date, with detailed epidemiological and clinical characteristics of the epidemic in the United Kingdom. METHODS A national diagnostic service and surveillance system was established in October 2004. Cases were confirmed by the presence of C. trachomatis and an LGV serovar (L1, L2, or L3) from genotyping. For confirmed cases, an enhanced surveillance questionnaire was sent to the clinician. RESULTS Through February 2006, a total of 327 cases of LGV were confirmed. Cases were diagnosed across the United Kingdom, with the majority from London (71%) and Brighton (13%). Case reports were received for 282 MSM. The majority (96%) had proctitis, many with severe local and systemic symptoms. There was a high level of coinfection with human immunodeficiency virus (76%), hepatitis C (19%), and other sexually transmitted infections (39%). Nine cases of human immunodeficiency virus infection were diagnosed around the same time as LGV. Most cases were acquired within the United Kingdom, although patients with early cases were more likely to report contacts in The Netherlands. CONCLUSIONS We found a significant burden of this once-rare sexually transmitted infection among MSM in the United Kingdom. LGV may be contributing to the epidemic of human immunodeficiency virus infection by facilitating transmission. Further control efforts are required, including awareness campaigns, continued detailed surveillance, and expanded chlamydia testing among MSM.

Emergence of high-level azithromycin resistance in Neisseria gonorrhoeae in England and Wales

OBJECTIVES This study aimed to investigate the origin of high-level azithromycin resistance that emerged in isolates of Neisseria gonorrhoeae in England and Wales in 2007, and to establish methods for identifying high-level azithromycin resistance. METHODS The Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) data from 2001-07 were examined for emerging trends in azithromycin susceptibility. Further to the identification of six high-level azithromycin-resistant isolates in GRASP 2007, an additional 102 isolates were selected on the basis of azithromycin susceptibility and geographic origin from the GRASP 2006 and 2007 collections. Susceptibility testing by Etest and disc diffusion was performed on all 108 isolates and 75 of these were typed by N. gonorrhoeae multiantigen sequence typing. RESULTS A slight drift towards higher MICs of azithromycin was observed in the gonococcal population since 2001. Of greater concern was the first example of a shift to high-level resistance observed in six isolates in 2007. All six isolates were sequence type 649, which was not observed in any of the lower-level azithromycin-resistant isolates from 2007 or in any isolates tested from the same geographical locations. Contact tracing data for one patient suggested a link with Scotland. Disc diffusion testing of all 108 isolates showed that azithromycin, but not erythromycin, discs can differentiate between low-level and high-level resistance. CONCLUSIONS High-level azithromycin resistance has emerged in England and Wales. Contact tracing and typing data suggest this may have originated from Scotland. Surveillance of azithromycin resistance will be key in controlling its further dissemination.

Cephalosporin MIC creep among gonococci: time for a pharmacodynamic rethink?

BACKGROUND Gonorrhoea has been among the easiest infections to cure with antibiotics. Nevertheless, emerging resistance has driven repeated treatment shifts. Decreased cephalosporin susceptibility is now being reported. We examined cephalosporin MIC trends for Neisseria gonorrhoeae in the UK and undertook pharmacodynamic analyses to predict efficacy against strains with raised MICs. METHODS Neisseria gonorrhoeae isolates were collected annually in a structured surveillance from 26 genitourinary medicine clinics in England and Wales. MICs were determined by agar dilution and confirmed by Etests. Pharmacodynamic modelling was performed for cefixime and ceftriaxone with Monte Carlo simulations. RESULTS There was a progressive emergence of small numbers of gonococci with cephalosporin MICs of 0.125-0.25 mg/L; these were not seen before 2005 but, for ceftriaxone and cefixime, respectively, accounted for 0.4% (95% confidence interval 0.2%-1.1%) and 2.8% (1.6%-4.8%) of the 1253 isolates collected in 2008; such MICs are 16-64 times the modal values for the species. Pharmacodynamic analysis was complicated by evidence that cephalosporins need a longer period with the free drug level above MIC than the 7-10 h required for penicillin G; nevertheless, pharmacodynamic analyses predict that failures with the standard 400 mg cefixime po and 250 mg ceftriaxone im regimens become likely around the present MIC maxima. CONCLUSIONS Gonococci with ceftriaxone and cefixime MICs of 0.125-0.25 mg/L are accumulating in the UK. These MICs lie on the edge of likely responsiveness to current regimens, which need review. Possible responses include: (i) higher cephalosporin doses; (ii) multidose cephalosporin regimens; (iii) multidrug regimens; (iv) microbiologically directed treatment; or, in the future, (v) drug cycling. The practicalities of these approaches are discussed.

High-Level Azithromycin Resistance Occurs in Neisseria gonorrhoeae as a Result of a Single Point Mutation in the 23S rRNA Genes

ABSTRACT High-level azithromycin resistance (AZM-HR), defined as a MIC of ≥256 mg/liter, emerged in Neisseria gonorrhoeae in the United Kingdom in 2004. To determine the mechanism of this novel phenotype, isolates from the United Kingdom that were AZM-HR (n, 19), moderately AZM resistant (MICs, 2 to 8 mg/liter) (n, 26), or sensitive (MICs, 0.12 to 0.25 mg/liter) (n, 4) were screened for methylase (erm) genes and for mutations in the mtrR promoter region, associated with efflux pump upregulation. All AZM-resistant isolates and 12 sensitive isolates were screened for mutations in domain V of each 23S rRNA allele. All AZM-HR isolates contained the A2059G mutation (Escherichia coli numbering) in three (3 isolates) or four (16 isolates) 23S rRNA alleles. Most (22/26) moderately AZM resistant isolates contained the C2611T mutation in at least 3/4 alleles. The remainder contained four wild-type alleles, as did 8/12 sensitive isolates, while one allele was mutated in the remaining four sensitive isolates. Serial passage of AZM-sensitive colonies on an erythromycin-containing medium selected AZM-HR if the parent strain already contained mutation A2059G in one 23S rRNA allele. The resultant AZM-HR strains contained four mutated alleles. Eight isolates (five moderately AZM resistant and three AZM-HR) contained mutations in the mtrR promoter. No methylase genes were detected. This is the first evidence that AZM-HR in gonococci may result from a single point mutation (A2059G) in the peptidyltransferase loop in domain V of the 23S rRNA gene. Mutation of a single allele is insufficient to confer AZM-HR, but AZM-HR can develop under selection pressure. The description of a novel resistance mechanism will aid in screening for the AZM-HR phenotype.

Whole-genome sequences of Chlamydia trachomatis directly from clinical samples without culture

The use of whole-genome sequencing as a tool for the study of infectious bacteria is of growing clinical interest. Chlamydia trachomatis is responsible for sexually transmitted infections and the blinding disease trachoma, which affect hundreds of millions of people worldwide. Recombination is widespread within the genome of C. trachomatis, thus whole-genome sequencing is necessary to understand the evolution, diversity, and epidemiology of this pathogen. Culture of C. trachomatis has, until now, been a prerequisite to obtain DNA for whole-genome sequencing; however, as C. trachomatis is an obligate intracellular pathogen, this procedure is technically demanding and time consuming. Discarded clinical samples represent a large resource for sequencing the genomes of pathogens, yet clinical swabs frequently contain very low levels of C. trachomatis DNA and large amounts of contaminating microbial and human DNA. To determine whether it is possible to obtain whole-genome sequences from bacteria without the need for culture, we have devised an approach that combines immunomagnetic separation (IMS) for targeted bacterial enrichment with multiple displacement amplification (MDA) for whole-genome amplification. Using IMS-MDA in conjunction with high-throughput multiplexed Illumina sequencing, we have produced the first whole bacterial genome sequences direct from clinical samples. We also show that this method can be used to generate genome data from nonviable archived samples. This method will prove a useful tool in answering questions relating to the biology of many difficult-to-culture or fastidious bacteria of clinical concern.

The prevalence of lymphogranuloma venereum infection in men who have sex with men: results of a multicentre case finding study

Objective: To determine the prevalence of lymphogranuloma venereum (LGV) and non-LGV associated serovars of urethral and rectal Chlamydia trachomatis (CT) infection in men who have sex with men (MSM). Design: Multicentre cross-sectional survey. Setting: Four genitourinary medicine clinics in the United Kingdom from 2006–7. Subjects: 4825 urethral and 6778 rectal samples from consecutive MSM attending for sexual health screening. Methods: Urethral swabs or urine and rectal swabs were tested for CT using standard nucleic acid amplification tests. Chlamydia-positive specimens were sent to the reference laboratory for serovar determination. Main outcome: Positivity for both LGV and non-LGV associated CT serovars; proportion of cases that were symptomatic. Results: The positivity (with 95% confidence intervals) in rectal samples was 6.06% (5.51% to 6.66%) for non-LGV CT and 0.90% (0.69% to 1.16%) for LGV; for urethral samples 3.21% (2.74% to 3.76%) for non-LGV CT and 0.04% (0.01% to 0.16%) for LGV. The majority of LGV was symptomatic (95% of rectal, one of two urethral cases); non-LGV chlamydia was mostly symptomatic in the urethra (68%) but not in the rectum (16%). Conclusions: Chlamydial infections are common in MSM attending for sexual health screening, and the majority are non-LGV associated serovars. We did not identify a large reservoir of asymptomatic LGV in the rectum or urethra. Testing for chlamydia from the rectum and urethra should be included for MSM requesting a sexual health screen, but serovar-typing is not indicated in the absence of symptoms. We have yet to identify the source of most cases of LGV in the UK.

New point of care Chlamydia Rapid Test—bridging the gap between diagnosis and treatment: performance evaluation study

Objective To evaluate the performance of a new Chlamydia Rapid Test with vaginal swab specimens as a potential tool for chlamydia diagnosis and screening. Design Performance evaluation study. Settings A young people’s sexual health centre (site 1) and two genitourinary medicine clinics (sites 2 and 3) in the United Kingdom. Participants 1349 women aged between 16 and 54 attending one of the three clinics. Main outcome measures Sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test versus polymerase chain reaction and strand displacement amplification assays; correlation between the Chlamydia Rapid Test visual signal and organism load; acceptability to participants of self collected vaginal swabs as the specimen type for Chlamydia testing. Results Polymerase chain reaction positivity rates for Chlamydia trachomatis infection were 8.4% (56/663) at site 1, 9.4% (36/385) at site 2, and 6.0% (18/301) at site 3. Compared with polymerase chain reaction assay, the resolved sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test were 83.5% (91/109), 98.9% (1224/1238), 86.7% (91/105), and 98.6% (1224/1242). Compared with strand displacement amplification assay, sensitivity and specificity of the Chlamydia Rapid Test were 81.6% (40/49) and 98.3% (578/588). Organism load of self collected vaginal swabs ranged from 5.97×102 to 1.09×109 Chlamydia plasmids per swab, which correlated well with the Chlamydia Rapid Test’s visual signal (r=0.6435, P<0.0001). Most (95.9%) surveyed participants felt comfortable about collecting their own swabs. Conclusions The performance of the Chlamydia Rapid Test with self collected vaginal swabs indicates that it would be an effective same day diagnostic and screening tool for Chlamydia infection in women. The availability of Chlamydia Rapid Test results within 30 minutes allows for immediate treatment and contact tracing, potentially reducing the risks of persistent infection and onward transmission. It could also provide a simple and reliable alternative to nucleic acid amplification tests in chlamydia screening programmes.

Identification of individuals with gonorrhoea within sexual networks: a population-based study

BACKGROUND Molecular typing of Neisseria gonorrhoeae and contact tracing provide a combined approach for analysis of sexual networks in metropolitan areas, although there are some difficulties in application. Our aim was to examine the application of high-throughput molecular approaches that can identify individuals in linked sexual networks. METHODS We characterised 2045 isolates of N gonorrhoeae from patients presenting at 13 major sexually transmitted infection clinics in London, UK, between June 1 and Nov 30, 2004. All isolates were assigned a sequence type (strain) on the basis of the sequences of internal fragments of two highly polymorphic loci, por and tbpB. These types were matched to demographic and behavioural data obtained at the clinic for each patient. We assessed the congruence in the demographic and behavioural characteristics of individuals infected with the same strain. FINDINGS We identified 21 prevalent strains in this diverse gonococcal population, each infecting between 20 and 124 individuals. Seven of these strains were predominantly from men who have sex with men; the remaining 14 were predominantly from heterosexual people. No differences were recorded between the strains associated with men who have sex with men in the demographic or behavioural characteristics of infected individuals. By contrast, significant differences in age (p<0.0001), ethnicity (p=0.001), proportion of women (p=0.01), and HIV status (p=0.03) were noted between the 14 prevalent heterosexual-associated strains. Heterosexuals with strains not shared by others in the sample were significantly older (p=0.0005) and more likely to have had sex outside the UK (p<0.0001) than those sharing a strain with at least one other. INTERPRETATION The discriminatory high throughput strain characterisation method applied here identified localised transmission networks and suggests little bridging between networks of men who have sex with men and heterosexual networks.

Molecular Typing of Neisseria gonorrhoeae Causing Repeated Infections: Evolution of Porin during Passage within a Community

Thirty-three Neisseria gonorrhoeae isolates from 15 persons infected multiple times with the same serovar were compared using por gene sequencing, opa-typing, and arbitrarily primed-polymerase chain reaction. All three molecular techniques were more discriminatory than serotyping and identified differences between some isolates belonging to the same serovar. Although there were differences among Por sequences within some serovars, 10 of 15 subjects became reinfected with gonococci expressing identical Por proteins. Sequence analysis of por genes revealed evidence of horizontal genetic exchange and point mutations in potential surface-exposed regions during passage in the community.

Immunogenicity of a serogroup B meningococcal vaccine against multiple Neisseria meningitidis strains in infants.

BACKGROUND The serogroup B meningococcus is responsible for the majority of cases of meningococcal disease in temperate countries. Infants and young children <2 years of age are at greatest risk of disease. This study assessed the immunogenicity in infants of a serogroup B meningococcal outer membrane protein vaccine that has been used extensively in disease outbreaks in Cuba and several Latin American countries and shown to be efficacious in teenagers. METHOD One hundred five healthy infants entering the routine vaccination schedule in Havana, Cuba, were given either 2 or 3 doses of the serogroup B meningococcal vaccine VA-MENGOC-BC at 3.5, 5.5 and 7.5 months of age. Immune response pre- and postvaccination was determined by the conventional serum bactericidal assay (SBA), a more sensitive novel whole blood bactericidal assay (WBA) and immunoglobulin ELISA. RESULTS In 52 and 46% of infants >50% killing of the vaccine serogroup B strain (B:4:P1.19,15) and serogroup C strain, respectively, was demonstrated by the WBA after 2 doses of the vaccine. Serum bactericidal activity (4-fold increase in titer) was induced in only 27% against the vaccine serogroup B strain and in 14% against the serogroup C strain. The changes in WBA and SBA were mirrored by the serogroup B and C immunoglobulin ELISA. Cross-reactive immunogenicity against other (heterologous) serogroup B strains was demonstrated for one of the four further strains assessed by WBA. By age 16 to 18 months SBA, WBA and ELISA responses had declined considerably. The addition of a third dose of vaccine did not appear to significantly influence immunogenicity at 17 months of age. CONCLUSION The serogroup B outer membrane protein vaccine VA-MENGOC-BC induces a demonstrable immune response in infants against both the serogroup B vaccine strain and against a serogroup C strain. Cross-reactive immunogenicity against other (heterologous) serogroup B strains is limited in this age group.