Antibiotic resistance inNeisseria gonorrhoeaeis diminishing available treatment options for gonorrhea: some possible remedies

Gonorrhea is essentially out of control in many settings and high disease rates are coupled with the spread of multiresistant gonococci. Increases in quinolone resistance have followed loss of the penicillins and tetracyclines as useful treatments. Decreasing susceptibility to third-generation cephalosporins is also reported. Over-reliance on antibiotic treatment as a disease control measure in settings with high disease rates and poor control of antibiotic usage is a significant contributor to the antimicrobial resistance reported. Conversely, containment of resistance is more likely to be achieved when combined with disease control principles shown to be effective. However, until a higher priority is given to funding for sexually transmitted diseases, this prospect is unlikely to eventuate and the possibility of untreatable gonorrhea becomes more real.

Cefpodoxime 10 μg disc screening test for detection of Neisseria gonorrhoeae with mosaic PBP2 and decreased susceptibility to extended-spectrum cephalosporins for public health purposes

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae remains a global public health problem. Susceptibility to first-line treatment extended-spectrum cephalosporins (ESCs) is decreasing worldwide resulting in therapeutic failures with oral ESCs. This study describes a cefpodoxime 10 μg disc test for screening for gonococci containing a penA mosaic allele encoding a mosaic penicillin-binding protein 2 (PBP2) and decreased ESC susceptibility. Selected clinical gonococcal isolates (n = 315), containing a high proportion of gonococci with decreased ESC susceptibility and high geographical, temporal and genetic diversity, were examined using agar dilution (n = 149; cefpodoxime and ceftriaxone) and Etest (n = 315; cefixime), and disc diffusion using a commercially available cefpodoxime 10 μg disc (n = 315). penA sequencing was performed on all isolates. The 2008 WHO gonococcal reference strains (n = 8) were included as quality controls. Using a ≤11 mm annular radius of growth inhibition as the breakpoint for the cefpodoxime 10 μg disc, all 78, with exception of one isolate (13 mm), mosaic PBP2-containing isolates, which also displayed decreased susceptibility to oral ESCs, were identified. In addition, 85 non-mosaic PBP2-containing isolates (44% of which contained a PBP2 A501 alteration) had annular radii ≤11 mm and raised minimal inhibitory concentrations to the ESCs. Screening for detection of mosaic PBP2-containing gonococci and decreased ESC susceptibility, most pronounced to oral ESCs, using a commercially available cefpodoxime 10 μg disc was rapid, inexpensive and sensitive. This test can be used in AMR surveillance programmes for public health purposes especially in less-resourced settings. Further studies to refine this disc testing-based approach are in progress.

Annual report of the Australian Gonococcal Surveillance Programme, 2008

The Australian Gonococcal Surveillance Programme monitors the antibiotic susceptibility of Neisseria gonorrhoeae isolated in all states and territories. In 2008 the in vitro susceptibility of 3,110 isolates of gonococci from public and private sector sources was determined by standardised methods. Different antibiotic susceptibility patterns were again seen in the various jurisdictions and regions. Resistance to the penicillins nationally was at 44% and ranged between 25% in Queensland and 73% in South Australia with the exception of the Northern Territory, where the proportion of drug resistant strains was 4%. Quinolone resistance in gonococci isolates also continued to increase so that nationally 54% of all isolates were ciprofloxacin-resistant, and most of this resistance was at high minimal inhibitory concentrations (MIC) levels. The proportions of quinolone resistant gonococci detected ranged between 80% in South Australia and 31% in Western Australia. All isolates remained sensitive to spectinomycin. Approximately 1.1% of isolates showed some decreased susceptibility to ceftriaxone (MIC 0.06 mg/L or more) and azithromycin resistance was also present in low numbers of gonococci with MICs up to 16 mg/L. A high proportion of gonococci examined in larger urban centres were from male patients and rectal and pharyngeal isolates were common in men. In other centres and in rural Australia the male to female ratio of cases was lower, and most isolates were from the genital tract.

Annual report of the Australian Meningococcal Surveillance Programme, 2008

In 2008, there were 260 laboratory-confirmed cases of invasive meningococcal disease (IMD) analysed by the National Neisseria Network, a nationwide network of reference laboratories. One hundred and forty-nine isolates of Neisseria meningitidis from invasive cases of meningococcal disease were available for which the phenotypes (serogroup, serotype and serosubtype) and antibiotic susceptibility were determined. An additional 111 cases were confirmed by non-culture based methods. Nationally, 223 (85%) laboratory-confirmed cases where a serogroup was determined were infected with serogroup B and 17 (6.5%) infected with serogroup C meningococci. Nationally, the total number of confirmed cases has remained relatively stable since 2006, but the number of cases in each jurisdiction may vary from year to year. Queensland had the highest number of recorded cases in 2008. Typical primary and secondary disease peaks were observed in those aged 4 years or less and in adolescents and young adults respectively. Serogroup B cases predominated in all age groups and jurisdictions. The common phenotypes circulating in Australia were again B:15:P1.7 and B:4:P1.4. Although serogroup C cases were numerically low, phenotype C:2a:P1.5 predominated in this group. No evidence of meningococcal capsular 'switching' was detected. About three-quarters of all isolates showed decreased susceptibility to the penicillin group of antibiotics (MIC 0.06-0.5 mg/L). All isolates remained susceptible to ceftriaxone. One isolate had reduced susceptibility to rifampicin and two to ciprofloxacin.

Two cases of failed ceftriaxone treatment in pharyngeal gonorrhoea verified by molecular microbiological methods

Diagnostic, genotypic and antibiotic-resistance determinants of Neisseria gonorrhoeae were analysed by molecular methods to verify the failure of ceftriaxone treatment in two cases of pharyngeal gonorrhoea. Monoplex assays were needed to define competitive inhibition of a positive Chlamydia PCR in a duplex assay. Different penA changes were detected in the N. gonorrhoeae isolated from the two cases. These were associated with raised ceftriaxone MICs of 0.03 and 0.016 mg l−1, which may have contributed to the treatment failures in these cases.

Phenotypic and genetic characterization of the 2008 WHO Neisseria gonorrhoeae reference strain panel intended for global quality assurance and quality control of gonococcal antimicrobial resistance surveillance for public health purposes

OBJECTIVES

Emergence and spread of antimicrobial resistance (AMR) in Neisseria gonorrhoeae remain a major global problem and expanded, but valid, AMR surveillance is crucial for public health purposes. The World Health Organization (WHO) Collaborating Centre in Sydney, Australia, continually evaluates N. gonorrhoeae strains used in quality control and assurance aspects of the national, WHO regional and international programmes for AMR surveillance it conducts. Here we phenotypically and genetically characterized the 2008 WHO N. gonorrhoeae reference panel, widely used under existing WHO AMR surveillance protocols.

MATERIALS AND METHODS

The eight N. gonorrhoeae WHO reference strains were phenotypically characterized by antibiogram, auxotype, serovar and prolyliminopeptidase screening; and genetically with regard to resistance plasmid types, polymorphisms in divergent genetic resistance-mediating loci (n = 9), porB sequencing and N. gonorrhoeae multi-antigen sequence typing.

RESULTS

The 2008 WHO reference strains represented all the important susceptible and resistant phenotypes, including corresponding resistance genotypes, and the range of resistances currently seen for relevant antimicrobials. Several pertinent additional phenotypic and genotypic markers, for example, epidemiological markers, were also determined.

CONCLUSIONS

The 2008 WHO N. gonorrhoeae reference strain panel was extensively characterized, which is crucial for the expansion of gonococcal AMR surveillance nationally and internationally. The panel is available through WHO sources for quality assurance and quality control aspects of current phenotypic testing protocols, to allow valid comparison of AMR data derived by divergent methods, and also for the control of present and future molecular assays for AMR detection. Additional WHO reference strains can be included as required by the emergence of additional resistant phenotypes and/or genotypes.

Annual report of the Australian Meningococcal Surveillance Programme, 2007--Amended

In 2007 there were 281 laboratory-confirmed cases of invasive meningococcal disease analysed by the National Neisseria Network, a nationwide network of reference laboratories. The phenotypes (serogroup, serotype and serosubtype) and antibiotic susceptibility of 154 isolates of Neisseria meningitidis from invasive cases of meningococcal disease were determined and an additional 127 cases were confirmed by non-culture based methods. Nationally, 223 (85%) confirmed cases where a serogroup was determined were infected with serogroup B and 17 (6.5%) with serogroup C meningococci. The total number of confirmed cases was 10 more than the 271 cases identified in 2006. Queensland and New South Wales recorded slight increases in case numbers and Victoria recorded a decline. Typical primary and secondary disease peaks were observed in those aged 4 years or less and in adolescents and young adults respectively. Serogroup B cases predominated in all age groups and jurisdictions. The common phenotypes circulating in Australia were B:15:P1.7, B:4:P1.4 and C:2a:P1.5. No evidence of meningococcal capsular 'switching' was detected. About three-quarters of all isolates showed decreased susceptibility to the penicillin group of antibiotics (MIC 0.06-0.5 mg/L). All isolates remained susceptible to rifampicin. A single serogroup B isolate had decreased susceptibility to ciprofloxacin (MIC 0.06 mg/L). This was the first local isolate of this type since the original report of this phenomenon in Australia in 2000.

Antibiotic resistance determinants in nosocomial strains of multidrug-resistant Acinetobacter baumannii

OBJECTIVES

To investigate the presence of resistance genes in nosocomial multidrug-resistant (MDR) Acinetobacter baumannii isolated from outbreak and sporadic settings.

METHODS

Thirty-two A. baumannii isolates were collected, 13 of which were involved in two outbreaks from different hospitals, which resulted in four deaths. The remaining 19 isolates were collected sporadically over 5 years from two other hospitals. The MICs of 25 antibiotics were determined for each isolate. PCR screening was carried out to identify possible genes that contributed to each resistance phenotype. Repetitive extragenic palindromic-PCR (REP-PCR) was performed to assess isolate clonality in conjunction with genotype data.

RESULTS

Between eight and 12 resistance determinants were detected in the 32 MDR A. baumannii isolates examined. These resistance determinants included the genes blaOXA-23 and ampC, with the upstream element ISAba1 promoting increased gene expression and subsequent resistance to carbapenems and cephalosporins, respectively. In all isolates, resistance to quinolones and fluoroquinolones was conferred by an S83L mutation in GyrA. Twenty-eight of the 32 isolates were also positive for tet(B), a tetracycline resistance determinant, blaTEM-1, which contributed to beta-lactam resistance, and strB, which contributed to aminoglycoside resistance. Class 1 integrons that harboured aacC1, aadA1, qacEDelta1 and sul1 were identified in 10 of the 32 isolates (31%) together with the kanamycin resistance gene, aphA1. A putative trimethoprim resistance gene, folA, was also identified in all isolates. REP-PCR together with genotyping identified three main clonal types.

CONCLUSIONS

Isolates of A. baumannii from both outbreak and sporadic cases possess at least eight resistance gene determinants that give rise to the MDR phenotype.

Annual report of the Australian Meningococcal Surveillance Programme, 2007

In 2007 there were 242 laboratory-confirmed cases of invasive meningococcal disease analysed by the National Neisseria Network, a nationwide network of reference laboratories. The phenotypes (serogroup, serotype and serosubtype) and antibiotic susceptibility of 127 isolates of Neisseria meningitidis from invasive cases of meningococcal disease were determined and an additional 115 cases were confirmed by non-culture based methods. Nationally, 192 (85%) confirmed cases where a serogroup was determined were infected with serogroup B and 14 (6.2%) with serogroup C meningococci. The total number of confirmed cases was 29 fewer than the 271 cases identified in 2006. The only jurisdiction to record a substantial increase in laboratory confirmed cases was New South Wales and this was in sporadic cases of serogroup B infection. Typical primary and secondary disease peaks were observed in those aged 4 years or less and in adolescents and young adults respectively. Serogroup B cases predominated in all age groups and jurisdictions. The common phenotypes circulating in Australia were B:15:P1.7, B:4:P1.4 and C:2a:P1.5. No evidence of meningococcal capsular 'switching' was detected. About three-quarters of all isolates showed decreased susceptibility to the penicillin group of antibiotics (minimum inhibitory concentration [MIC] 0.06-0.5 mg/L). All isolates remained susceptible to rifampicin. A single serogroup B isolate had decreased susceptibility to ciprofloxacin (MIC 0.06 mg/L). This was the first local isolate of this type since the original report of this phenomenon in Australia in 2000.

Using epidemiological and molecular methods to investigate an outbreak of gonorrhoea associated with heterosexual contact in Newcastle, NSW, Australia

BACKGROUND

We report a cluster of gonorrhoea among mainly heterosexual men that occurred in October 2005, which was first identified when routine weekly surveillance review procedures indicated a three-fold increase in reporting rates compared with historical data.

METHODS

Each case was followed up with the treating medical officer to review treatment regimes and risk exposures, and to carry out enhanced contact tracing. The phenotype and genotype of the outbreak gonococcal isolates and gonococci prevalent in the months preceding and following the cluster were determined. Links between cases reported from the local Sexual Health Clinic and those reported by general practitioners were established.

RESULTS

Laboratory data indicated that a particular gonococcal subtype (ST 225 and NR/Brpyst) was prevalent during the outbreak.

CONCLUSIONS

Gonorrhoea rates returned to pre-outbreak levels following a targeted health promotion intervention with no further cases of the outbreak subtype detected.

Applications of molecular testing in clinical laboratories for the diagnosis and control of gonorrhea

The potential for enhanced diagnosis and control of gonococcal infection through the application of advances in molecular medicine is now being realized. However, the introduction of diagnostic nucleic acid amplification assays (NAATs) revealed some significant limitations of these applications. Resolution of some, but not all, of these problems has led to recommendations for refined testing algorithms and a better recognition and acceptance of the limitations of NAATs. Resource restriction has limited the use of diagnostic NAATs, especially in less-developed countries where disease rates are highest. However, NAATs have also proved useful in public health approaches to gonorrhea control in all settings. Additional applications including molecular typing of gonococci to identify and interrupt gonococcal transmission chains and definition of antimicrobial resistance patterns in the gonococcus have been proposed. These approaches, especially those for antimicrobial resistance determination, have been less successful for a number of reasons, including their cost and other unresolved issues.

The role of antimicrobial resistance monitoring in Neisseria gonorrhoeae

Treatment regimens for most sexually transmitted diseases of bacterial origin are well established. For example, treatment of infections with Chlamydia trachomatis is usually now with macrolides, and Treponema pallidum is still reliably susceptible to penicillins. However, antibiotic treatment for gonorrhoea is more complicated because of the propensity of the gonococcus to develop antimicrobial resistance (AMR), so that standard treatment protocols for gonorrhoea require regular review. Additionally, treatment for gonorrhoea is usually by means of a single dose regimen (for better compliance with treatment) and is best given at first presentation/diagnosis (to reduce the potential for disease spread). Testing of individual isolates on an emerging basis is not a practical means of guiding treatment for this situation. Thus, standardised treatments are determinedfrom an epidemiologically-based assessment of the susceptibility of gonococci prevalent in a region or community. Another complicating factor for treatment of gonococcal infection is the frequency of gene recombination in Neisseria gonorrhoeae that results in continuing rearrangement of and within gonococcal populations. AMR patterns within different sexual networks are also affected and, in addition to changes over time, patterns of resistance also differ substantially in different parts of Australia.

Laboratory issues in STD diagnosis and their application to disease control in an Australian context

This issue of Microbiology Australia features a selection of articles on novel and pragmatic contributions from Australian clinical laboratories to the diagnosis, management and control of sexually transmitted diseases (STDs).

Recent World Health Organization initiatives for antimicrobial resistance control

The World Health Organization (WHO) overseeing of antimicrobial resistance (AMR) containment issues in the last decade has varied in intensity. From 1999 onwards, concerted focus from the WHO led to the development of a multi-disciplinary framework for AMR containment at a country level. However, implementation of the WHO Global Strategy for the Containment of Antimicrobial Resistance (the Global Strategy) was overtaken first by events in the USA in 2001 and later by related and other bio-security issues. By 2003, loss of funding and a restructured WHO saw AMR initiatives curtailed. Interest in AMR at the WHO has been recently rekindled and it is hoped that renewed attention will again be focused on this issue by the WHO and its member states.

Towards an integrated approach to the problem of antimicrobial resistance in Australia

'The threat is real, the science is in, the time for action is now!' A familiar refrain that for most of us is associated with the debate surrounding global warming, but surely equally applicable to the situation surrounding its microbiological equivalent ? antimicrobial resistance (AMR). We are all well aware of AMR and the consequences of its emergence and spread, following the recognition of this phenomenon when the ?antibiotic era? began only a few decades ago. Perhaps we have been somewhat complacent about AMR, in that we have relied overmuch on the continuing development of new and better antimicrobial agents. As the efficacy of older antimicrobials wanes and the supply of new agents declines in the face of increasing AMR, some have suggested that we may be facing a ?post-antibiotic era?. This edition of Microbiology Australia provides an overview of the current situation and effects of AMR, especially with regard to Australia. The topic is extensive and the ramifications wide, so the contributions in this edition are aimed to provide only a flavour of the intricacies of the overall problem of AMR, the mechanisms involved, and the known and possible means by which AMR may be contained.

Global transmission of prolyliminopeptidase-negative Neisseria gonorrhoeae strains: implications for changes in diagnostic strategies

BACKGROUND

Species confirmation of Neisseria gonorrhoeae is commonly performed with biochemical kits, rely on the activity of the enzyme prolyliminopeptidase (PIP). This enzyme has previously been considered to be almost universally present in N gonorrhoeae. However, increasing numbers of N gonorrhoeae isolates lacking PIP activity have been identified.

OBJECTIVES

To investigate the possibility of a widespread transmission of one or several N gonorrhoeae PIP-negative strains among several countries worldwide.

METHODS

PIP-negative N gonorrhoeae isolates cultured from 2001 to 2004 in Australia, New Zealand and Scotland were comprehensively characterised and compared with previous data from England and Denmark. All isolates were characterised by antibiotic susceptibility testing, serovar determination, pulsed-field gel electrophoresis (PFGE), opa-typing, sequencing of the entire porB gene and N gonorrhoeae multiantigen sequence typing (NG-MAST).

RESULTS

Most (83%) of the viable Australian isolates, and all the New Zealand and Scottish isolates were assigned serovar IB-4, with similar antibiograms, nearly identical porB1b gene sequences, identical (ST210) or highly related (ST292, ST1259) NG-MAST STs, and indistinguishable or related PFGE fingerprints as well as opa-types. The isolates showed characteristics indistinguishable or highly related to the previously described English and Danish outbreak strain.

CONCLUSIONS

A comprehensive characterisation indicates a widespread dissemination, mainly among men who have sex with men (MSM), of indistinguishable and highly related genotypes that have evolved from a single N gonorrhoeae PIP-negative serovar IB-4 strain among several countries worldwide. An increased awareness of PIP-negative N gonorrhoeae strains is crucial and changes in the diagnostic strategies may need to be considered.

Prevalence of antimicrobial resistance in Neisseria gonorrhoeae in an HIV/AIDS clinic

Antimicrobial resistance in Neisseria gonorrhoeae is increasing in the Pacific region. The standard antibiotic used in urban Australia is intramuscular ceftriaxone. Isolates with reduced sensitivity are being isolated; however, resistance to ceftriaxone has yet to occur. Continued surveillance of antimicrobial resistance in the pathogen, with communication between clinic and laboratory, is needed to ensure optimal treatment of infection.

Evaluation of opa-based real-time PCR for detection of Neisseria gonorrhoeae

OBJECTIVES

Detection of Neisseria gonorrhoeae by commercial and in-house-based assays has been hampered by false-positive and false-negative results. The current study describes a sensitive and specific real-time 5'-nuclease PCR assay targeting a 90-bp region of the multicopy opa gene.

GOAL

To evaluate the sensitivity and specificity of this assay in detection of gonococcus.

STUDY

Sensitivity and specificity were determined by testing a panel of 173 microorganisms. In addition, 135 clinical samples previously evaluated by 4 nucleic acid amplification methods were also tested.

RESULTS

A sensitivity of 1 copy per reaction was achieved. Positive results were only obtained for N gonorrhoeae strains including 20 cppB-negative strains. Overall, 134 of 135 clinical sample results agreed with the consensus nucleic amplification methods.

CONCLUSION

This study demonstrates opa-based target can be used as an accurate and rapid PCR assay for the detection of N gonorrhoeae in clinical specimens.

Patterns of quinolone susceptibility in Campylobacter jejuni associated with different gyrA mutations

AIMS

To investigate the diversity of genetic mutation in the quinolone resistance-determining region (QRDR) of gyrA in clinical isolates and laboratory-derived mutants of Campylobacter jejuni resistant to ciprofloxacin (CipR) and to determine the influence of this mutation on the susceptibility of the organisms to different quinolone antibiotics.

METHODS

Laboratory-derived CipR mutants were obtained from C. jejuni NCTC 11 168 and six quinolone-sensitive faecal isolates (parent prototypes) grown in sub-inhibitory concentrations of ciprofloxacin. Initial mutants found to be CipR were designated 'primary mutants' and subjected to a repeat of this process to select 'secondary mutants' with increased resistance. The susceptibility of the mutants and an additional six clinical isolates of CipR C. jejuni to seven quinolone antibiotics was determined by measuring their MICs. The QRDR of gyrA in all strains was amplified by PCR, sequenced and compared with that of the L04566 C. jejuni gyrA gene.

RESULTS

All six CipR clinical isolates contained a Thr-86-Ile mutation. This was also the commonest mutation found amongst the laboratory derived CipR strains. Other derived mutations in the in vitro derived CipR group included Asp-90-Asn, Thr-86-Ala, and a previously unreported double mutation, Asp-85-Tyr and Thr-86-Ile. Strains with the Thr-86-Ile mutation had the highest MICs to seven different quinolones. CipR strains with other single mutations had a lower range of MICs. There were no additional QRDR mutational changes detected in secondary mutants even where MICs to the fluoroquinolones were higher than in primary mutants.

CONCLUSIONS

Thr-86-Ile mutations were common in both clinical and laboratory derived CipR strains. Other mutations found amongst the latter strains were more sensitive to the fluoroquinolones. Different QRDR changes in gyrA differentially affected the susceptibility of CipR C. jejuni to the various fluoroquinolones.

Current concepts in the management of gonorrhoea

The incidence of gonorrhoea is again rising in developed countries and a high disease rate has been maintained in less developed regions for a number of years. The need not only for treatment of the individual but also for control of gonorrhoea at a community level has increased significantly following recognition of its role in the amplification of human immunodeficiency virus (HIV) transmission. A sustainable decrease in the incidence of gonorrhoea and other sexually transmitted diseases (STDs) requires an integrated approach combining improved prevention, better diagnosis and optimal treatment. Effective antibiotic treatment is an essential element of this approach. However, antibiotic treatment of gonorrhoea has been severely hampered by the development of antibiotic resistance in Neisseria gonorrhoeae, to the extent that many therapies are no longer effective. Those treatments that retain acceptable efficacy are often unaffordable where they are most needed. Penicillins and tetracyclines should no longer be used in gonococcal disease, there are limitations on the effectiveness of newer macrolides and spectinomycin and in many parts of the world quinolones have been withdrawn from schedules for the treatment of gonorrhoea. Of all the current agents used to treat all forms of gonococcal disease, only the third generation cephalosporins (most notably ceftriaxone) have retained their efficacy; however, decreased susceptibility to these antibiotics has also appeared. Continuing reliance on antibiotic treatment for controlling gonorrhoea in the absence of other necessary approaches will see a further deterioration in the situation. In these circumstances the possibility that gonorrhoea will be untreatable becomes more real.

Annual report of the Australian Gonococcal Surveillance Programme, 1999

The primary aim of the Australian Gonococcal Surveillance Programme (AGSP) is to monitor the antibiotic susceptibility of Neisseria gonorrhoeae. In 1999 the AGSP examined 3,740 isolates of gonococci from all States and Territories. The rates and sites of infection and antibiotic susceptibility patterns varied considerably between regions, reflecting the considerable differences between non-urban and urban gonorrhoea in Australia. Resistance to the penicillin and quinolone groups of antibiotics was highest in urban centres. Although penicillins remained suitable for use in many parts of non-urban Australia, enhanced surveillance is required as levels of resistance increase. Endemic transmission of quinolone-resistant gonococci (QRNG) in homosexually active men increased substantially in New South Wales and Victoria where more then 90% of all QRNG were found. QRNG in other centres continued to be isolated mostly from overseas travellers and at a low frequency. All isolates remained sensitive to spectinomycin and ceftriaxone. A further increase in the number of gonococcal isolates from homosexually active men was recorded in New South Wales and Victoria. Strains examined in South Australia, New South Wales and Victoria were predominantly from male patients and rectal and pharyngeal isolates were common. In other centres the male to female ratio of cases was lower, and most isolates were from the genital tract in rates similar to those occurring in previous years. The impact of non-culture based detection methods will adversely affect the ability of the AGSP to monitor trends in gonococcal disease in future years.

Unusual cluster of mild invasive serogroup C meningococcal infection in a university college

The objective of this study was to describe the epidemiology and public health response to an apparent cluster of Neisseria meningitidis serogroup C infection in university students in a residential college. A conventional epidemiological approach was taken, supported by routine and novel diagnostic techniques. Over the two days of 21-22 August 1997, three cases of suspected meningococcal infection were notified from a residential college complex at a university campus in the Sydney metropolitan area. Neisseria meningitidis was grown from throat swabs of all three cases, and was isolated from the blood of one case only. All three isolates were typed as C:2a:P1.5,2. Seroconversion was demonstrated by a novel method in the three cases. Rifampicin was given to all identified contacts. Forty-seven days after the index case, a 19 year old female living in the same complex was diagnosed with bacterial meningitis, and identified contacts given rifampicin. When this isolate was found to be group C, it was decided to vaccinate residents of the college complex. Genotyping and serotyping (C:2a:P1.5) later revealed the fourth isolate to be distinct from isolates from Cases 1-3. In conclusion the authors note that Australia's increasing capacity to type meningococcal strains is essential to understanding the epidemiology of this disease. Furthermore, typing information is of critical importance when decisions are made regarding mass vaccination. As early antibiotic treatment may inhibit isolation of the organism, development of novel approaches to diagnosis and typing should be supported.

Annual report of the Australian Gonococcal Surveillance Programme 1996

In 1996 the Australian Gonococcal Surveillance Programme (AGSP) examined 2,753 isolates of Neisseria gonorrhoeae. The source of isolates, site of infection and antibiotic susceptibility patterns showed considerable regional variation. Strains examined in Adelaide, Sydney and Melbourne were predominantly from male patients where rectal and pharyngeal isolates were common. Cases in other centres had a much lower male:female ratio and most were genital tract isolates. Resistance to the penicillin and quinolone groups of antibiotics was highest in Sydney and Melbourne. Gonococcal resistance to the penicillins was similar to previous years. Quinolone-resistant Neisseria gonorrhoeae (QRNG) were isolated mostly from overseas travellers. However, some local transmission of QRNG was documented in Sydney. All isolates were sensitive to spectinomycin and ceftriaxone.

Arthritis in the highlands of Papua New Guinea

Acute polyarthritis is an important cause of morbidity in many tropical countries. Classification has often been difficult, with the term tropical polyarthritis used for those in whom a diagnosis could not be made. The implication that this is a distinct entity is probably incorrect, with likely causes being septic arthritis or post-infective reactive arthritis. This study aimed to determine the types of arthritis found in 43 patients (30 men) presenting consecutively to the Goroka Base Hospital in the Eastern Highlands of Papua New Guinea. Gonococcal arthritis was diagnosed in eight patients (six men) on the basis of isolation of Neisseria gonorrhoeae from the joint aspirate. In all cases the N gonorrhoeae was identified by the closed culture system on chocolate agar, but not always by routine plating. There were no specific clinical features that identified patients with a gonococcal septic arthritis. The remaining 34 patients had an undifferentiated oligoarthritis. The pattern of arthritis in men and women was of a lower limb pauciarticular arthritis with a predilection for the knee and ankle joints. A total of 30% of male patients had a history of urethral discharge and 44% of all patients had preceding diarrhoea. Arthritis was the only feature in 59% of patients and in 32% there was an associated enthesitis. In this study most patients had an oligoarthritis consistent with a reactive arthritis or a septic arthritis due to N gonorrhoeae. Broth inoculation of synovial fluid was the best method to isolate N gonorrhoeae, with standard methods for gonococcal isolation failing in some patients. It is recommended that the term 'tropical polyarthritis' is no longer used as it does not refer to a specific entity but consists of several known arthritides.

Direct detection of Neisseria gonorrhoeae with monoclonal antibodies characterized by serotyping reagents

A panel of monoclonal antibodies (MAbs) directed to outer membrane protein I were generated with the ultimate aim of detecting Neisseria gonorrhoeae in patient samples by a direct immunofluorescence (IF) test. In an initial evaluation of the sensitivity of these reagents, a cocktail of six IF MAbs recognized 491 (91%) of 540 gonococci isolates from several centers in Sydney, Australia. IF MAbs designated 185 and 228 recognized serovars of WI serogroup and IF MAbs 208, 210, and 312 recognized serovars of WII/III serogroup. IF MAb 198 recognized serovars within both serogroups. Three additional IF MAbs, designated 322, 323, and 330, were then generated by using strains which failed to react with the original MAb cocktail and which belonged to particular serovars. The new cocktail of nine IF MAbs recognized 96% of the gonococcal isolates, which incidentally contained representatives of serovars shown to have a worldwide distribution in previous studies. Although subtle differences were apparent in the reaction patterns found with coagglutination (serotyping) and IF, there nonetheless seems to be merit in the approach of continually evaluating the sensitivity of diagnostic reagents such as MAbs. This is especially true with an organism such as N. gonorrhoeae, which has the capacity to regularly alter the antigenic structure of its outer membrane proteins.