Articles

Neisseria gonorrhoeae isolates from four centres in Papua New Guinea
remain susceptible to amoxycillin-clavulanate therapy
PAMELA J. TOLIMAN1, TONY LUPIWA1, 2, GREGORY J. LAW3, JOHN C. REEDER1, 4 AND PETER M. SIBA1 Papua New Guinea Institute of Medical Research, Goroka and Disease Control Branch,
Division of Public Health, Papua New Guinea Department of Health, Port Moresby
Antibiotic-resistant strains of Neisseria gonorrrhoeae have the potential to undermine
treatment and control of gonorrhoea, which remains a highly prevalent sexually
transmitted infection (STI) in Papua New Guinea (PNG). The standard treatment regimen
for gonorrhoea in PNG based on amoxycillin and clavulanic acid (amoxycillin-clavulanate)
was introduced about 15 years ago and there is some concern that over time circulating
strains may have developed resistance to this therapy. To investigate this, N. gonorrhoeae
isolates (n=52) were collected from STI clinics in geographically representative centres
in PNG and tested for their in vitro susceptibility to a range of antibiotics. All 52 isolates
tested were found susceptible to amoxycillin-clavulanate, despite 40% (n=21) being
penicillinase producers and thus resistant to penicillin. These findings indicate that
amoxycillin-clavulanate therapy remains an effective treatment for gonococcal infections
in PNG, and support the maintenance of the present standard treatment for gonorrhoea
in PNG.
Introduction
and the Eastern Highlands Province (21%) (1,4). Furthermore, in a seemingly asymptomatic rural population, gonococcal coccoid bacterium Neisseria gonorrhoeae, infection was detected in 18% of women (3). remains one of the most common sexually transmitted infections (STIs) in Papua New While data on STIs in PNG are limited, the Guinea (PNG) (1-4). Rates have been steadily increasing over the last four decades (5) and recently reported over 17,000 cases of genital discharge syndrome (GDS) nationally in the estimates the incidence rate for gonorrhoea first half of 2008 alone (7). The large burden of STIs in PNG prompted the prioritization of However, various studies have shown higher STI management in the National Health Plan rates of gonococcal infection in selected 2001-2010 and the PNG National Strategic populations within PNG and a survey of STI Plan on HIV/AIDS [human immunodeficiency clinics reported that 54% of male attenders virus/acquired immune deficiency syndrome] were clinically diagnosed with gonorrhoea (2). 2006-2010 (6,8). Accordingly, the NDoH has A high prevalence of gonococcal infection, detected by polymerase chain reaction (PCR), management approach. Currently all cases workers in Port Moresby (34%), Lae (24%) 1 Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, 2 Present address: National AIDS Council Secretariat, PO Box 1345, Boroko, National Capital District 111, 3 Disease Control Branch, Division of Public Health, National Department of Health, PO Box 807, Waigani, National Capital District 131, Papua New Guinea 4 Present address: Burnet Institute, GPO Box 2284, Melbourne, Victoria 3001, Australia Papua New Guinea Medical Journal Volume 53, No 1-2, Mar-Jun 2010 and 2005 at the STI clinics in Port Moresby, Lae, Mt Hagen and Goroka. During the study period, patients were invited to participate if they presented at the STI clinic with UDS trichomoniasis in a single-dose therapy. This regimen consists of 1 g Augmentin 500, 2 g azithromycin with either 1 g tinidazole twice examination. A urethral swab was collected daily for three days (women) or 2 g tinidazole (men) (9). Augmentin 500 contains 500 mg of amoxycillin and 125 mg of clavulanic acid. obtained from the PNG Medical Research Advisory Committee. potentially be undermined by the ability of the Isolation of N. gonorrhoeae
aetiological agent, N. gonorrhoeae, to develop and acquire antibiotic resistance genes (10,11). Thus, the monitoring of antibiotic resistance in N. gonorrhoeae is essential for (vancomycin, Colistin sulphate and nystatin) Thebarton, SA, Australia) and chocolate agar. The inoculated media were placed in a candle laboratory, where the media were streaked and incubated at 37°C in the candle jar for up However, the source of PNG isolates tested in this program is unknown. In PNG, routine culture of N. gonorrhoeae is conducted only Suspected colonies that grew within the 48- at the Port Moresby General Hospital (PMGH) hour incubation period were presumptively (14), so there is concern that the PNG data identified as N. gonorrhoeae if they were Gram-negative diplococci, oxidase positive representative of susceptibility patterns and superoxol positive. The rapid carbon throughout the rest of the country. There is utilization test as described by the WHO was also a lack of data from either PMGH or WPR used to confirm the identity of N. gonorrhoeae GASP on the susceptibility of gonococcal isolates to amoxycillin and clavulanic acid (amoxycillin-clavulanate), which is the basis Antimicrobial susceptibility testing
of gonorrhoea treatment in the country (13,14). Furthermore, despite the importance Antimicrobial susceptibility testing of N. of resistance monitoring, the most recent gonorrhoeae isolates was done using the disk multicentre investigation into gonococcal diffusion method on Columbia chocolate agar antimicrobial susceptibility patterns in PNG as described by the WHO (15). The antibiotic was carried out well over fifteen years ago Australia) used contained amoxycillin and clavulanic acid in a 2:1 ratio (30 ìg), Amoxycillin-clavulanate has been used to azithromycin (15 ìg), ceftriaxone (0.5 ìg), treat gonorrhoea in PNG for the last 15 years, ciprofloxacin (1 ìg), erythromycin (15 ìg), raising concern that isolates in current penicillin G (0.1 IU), spectinomycin (100 ìg) circulation may be developing resistance to therapy (9). To investigate this, we conducted inhibitory concentration (MIC) was measured surveillance of antibiotic resistance in N. for isolates that displayed a diminished gonorrhoeae in four major centres in PNG. susceptibility to an antibiotic using the Etest® system (AB Biodisk, Dalvägen, Solna, Sweden). Penicillinase-producing N. Study population and sample collection
gonorrhoeae (PPNG) were identified using a â-lactamase indicator stick (Oxoid Limited, Papua New Guinea Medical Journal Volume 53, No 1-2, Mar-Jun 2010 Samples were collected from a total of 145 Discussion
women and 65 men during the study period. N. gonorrhoeae was cultured from 31% All gonococcal isolates tested in this study (n=65) of patients : 14% (n=21) of women were susceptible in vitro to amoxycillin- and 68% (n=44) of men. N. gonorrhoeae was clavulanate. On the basis of this finding, the isolated more commonly from urethral swabs current treatment regimen of 1 g of Augmentin of men than cervical swabs of women (odds 500 with an additional 2 g of amoxycillin and ratio 12.4, p <0.001). A total of 65 gonococcal 1 g of probenecid should remain the standard strains were isolated, of which 52 (80%) treatment for gonorrhoea, as part of the underwent full antimicrobial susceptibility syndromic management protocol for GDS in 21 isolates resistant to penicillin were (2,13,16,17), this study found that PPNG tested. Of these, 7 isolates (33%) had an MIC of ≥32 ìg/l, the highest concentration on gonococcal isolates that cause disease in the the penicillin Etest® strip used (Table 2). All isolates remained susceptible to amoxycillin- resistant to â-lactam antibiotics, because the clavulanate, including the PPNG isolates. All penicillinase produced by PPNG hydrolyses non-PPNG (60%, n=31) were susceptible to the active component of â-lactam antibiotics, penicillin (Table 1). One isolate (2%) from particularly penicillins (11,18). All PPNG Lae was resistant to ciprofloxacin and had detected in this study were resistant to penicillin, with high MICs to the antibiotic. tetracycline were observed in 19% (n=10) of isolates tested (Table 2). All isolates collected amoxycillin-clavulanate. Clavulanic acid, a â-lactamase inhibitor, blocks the activity of spectinomycin, erythromycin, azithromycin penicillinase making the organism susceptible ANTIMICROBIAL SUSCEPTIBILITY OF NEISSERIA GONORRHOEAE ISOLATES Papua New Guinea Medical Journal Volume 53, No 1-2, Mar-Jun 2010 NUMBER OF NEISSERIA GONORRHOEAE ISOLATES WITH ELEVATED MINIMUM throughout Asia and parts of the Pacific persistence of PPNG in the community, the (13). In this study, one isolate (2%) was standard treatment for gonorrhoea remains effective and thus should be maintained. susceptible to amoxycillin-clavulanate. Elevated MICs to tetracycline were to penicillin has been reported previously in PNG (2,16,19). CMR to penicillin is usually doxycycline is selecting strains that are manifested in PPNG resistant to amoxycillin- becoming resistant to tetracycline. While clavulanate or with elevated MICs to penicillin doxycycline is not used to treat gonorrhoea in PNG, it is occasionally used to treat detected in any of the isolates tested, as all chlamydia, pelvic inflammatory disease and isolates were susceptible to amoxycillin- clavulanate and all non-PPNG were susceptible to penicillin. Despite the shortcomings of culture N. gonorrhoeae was isolated from 31% of Resistance to ciprofloxacin and tetracycline such, it is imperative that the standard ciprofloxacin, are not commonly used to treat treatment protocol be regularly monitored. gonorrhoea in PNG and selective pressure from quinolone use would be minimal. The treatment protocols, susceptibility to a range occurrence of quinolone resistance has been of antibiotics must be regularly monitored low and sporadic suggesting that quinolone- becomes ineffective (11,12). On the basis organisms, as their occurrence is widespread Papua New Guinea Medical Journal Volume 53, No 1-2, Mar-Jun 2010 erythromycin, azithromycin and ceftriaxone remain effective and could offer alternative options for gonococcal treatment in PNG. Conclusion
language and culture in PNG give rise to Given the high prevalence of STIs in PNG, complex transmission dynamics of STIs in the their effective treatment is important in itself country. Hence it is vital that gonococcal but also an integral part of PNG’s response susceptibility patterns be monitored across to the HIV epidemic. Gonorrhoea, while easily different sites within PNG. The four centres curable, continues to be a significant STI in in this study were selected for their moderate the country. Amoxycillin-clavulanate remains to high incidence of gonococcal infection (8). effective in clearing circulating strains of N. Port Moresby, the capital and most populated gonorrhoeae in PNG and therefore the current city of PNG, is considered the gateway to the standard treatment regimen for gonorrhoea country. Lae, the second largest city, is also should be maintained. However, it is vital that a strategic port and the start of the Okuk regularly monitored so that the national Highlands Region. Mt Hagen and Goroka are treatment protocols continue to be evidence major centres in the Highlands Region and are situated along the Okuk Highway. Obviously, a national standard treatment ACKNOWLEDGEMENTS
protocol should be effective throughout the entire country. Isolates collected across all This study was funded through the National four sites were susceptible to amoxycillin- HIV and AIDS Support Project. The authors clavulanate indicating that the standard sincerely thank the participating staff and treatment is still effective across PNG. patients of Heduru Clinic, Friends Clinic, Tininga Clinic and Michael Alpers Clinic. The At present, culture-based methods are the authors also thank the Management of Port gold standard for antibiotic susceptibility Moresby General Hospital, Angau Memorial testing (11) but there are many challenges associated with the culture of N. gonorrhoeae, Goroka General Hospital for their support of particularly in a resource-limited setting such this study. Tilda Orami and Mition Yoannes as PNG. Firstly, N. gonorrhoeae is fastidious provided invaluable laboratory support and and difficult to culture, particularly from technical advice for this study. Dr Andrew Greenhill and Dr Claire Ryan provided critical competing flora in the female genital tract (20). The presence of competing flora might in part explain the significant difference in REFERENCES
isolation of the organism from men compared to women. Secondly, most hospitals in PNG Gare J, Lupiwa T, Suarkia DL, Paniu MM,
Wahasoka A, Nivia H, Kono J, Yeka W, Reeder
resources to carry out routine gonococcal JC, Mgone CS. High prevalence of sexually
transmitted infections among female sex workers
culture. This is particularly important since in the Eastern Highlands Province of Papua New successful culture of N. gonorrhoeae is Guinea: correlates and recommendations. Sex dependent on many factors such as technique Hudson BJ, van der Meijden WI, Lupiwa T,
Howard P, Tabua T, Tapsall JW, Phillips EA,
conditions, quality of culture medium and Lennox VA, Backhouse JL, Pyakalyia T. A survey
incubation conditions (20). The development of sexually transmitted diseases in five STD clinics of an assay that is able to detect relevant in Papua New Guinea. PNG Med J 1994;37:152- factors associated with resistance in N. gonorrhoeae without the need for a viable Mgone CS, Lupiwa T, Yeka W. High prevalence of
Neisseria gonorrhoeae and multiple sexually
organism would allow a more representative transmitted diseases among rural women in the monitoring of antibiotic susceptibility patterns Eastern Highlands Province of Papua New Guinea, throughout the country. Recently, a number detected by polymerase chain reaction. Sex Transm of molecular assays have been developed to Mgone CS, Passey ME, Anang J, Peter W, Lupiwa
detect specific mutations associated with N. T, Russell DM, Babona D, Alpers MP. Human
gonorrhoeae antimicrobial resistance using immunodeficiency virus and other sexually non-viable organisms (21,22). Such assays, transmitted infections among female sex workers in two major cities in Papua New Guinea. Sex Papua New Guinea Medical Journal Volume 53, No 1-2, Mar-Jun 2010 East Asia Series No 33. New Delhi: WHO Regional Lombange CK. Trends in sexually transmitted
disease incidence in Papua New Guinea. PNG Med 16 Montgomery J, Lupiwa T, Hudson B. Resistance
in Neisseria gonorrhoeae in the Goroka and Madang Papua New Guinea Department of Health. Papua
areas of PNG. Abstract in Program and Abstracts New Guinea National Health Plan 2001-2010. Port of the Twenty-fourth Annual Symposium of the Moresby: Department of Health, Aug 2000. Medical Society of Papua New Guinea, Lae, 9-10 Papua New Guinea Department of Health. The
2008 STI, HIV and AIDS Six Monthly Surveillance 17 Passey M, Mgone CS, McEvoy P, Lupiwa T,
Report, January - June 2008. Port Moresby: STI, Yoannes M, Winston G. Gonococcal drug
HIV and AIDS Surveillance Unit, National sensitivities, trichomoniasis and evaluation of risk factors for chlamydial infection. Final Report of National AIDS Council of Papua New Guinea.
Research Project to National Department of Health. Papua New Guinea National Strategic Plan on HIV/ Goroka: Papua New Guinea Institute of Medical AIDS 2008-2012. Port Moresby: National AIDS 18 Johnson SR, Morse SA. Antibiotic resistance in
Papua New Guinea Department of Health.
Neisseria gonorrhoeae: genetics and mechanisms Standard Management of Sexually Transmitted of resistance. Sex Transm Dis 1988;15:217-224. Infections and Genital Conditions in Papua New 19 Michael A, Vince J, Igo JD, Sindigaim C, Lupiwa
Guinea: A Manual for Health Workers in PNG. Port T, Yoannes M, Wal TO, Ove P, Hombhange M,
Moresby: National Department of Health, 2006. Roi P, Passey M, Winston G, Lehmann D, Mgone
10 Ison CA, Dillon JA, Tapsall JW. The epidemiology
C, Alpers M. Antibiotic susceptibility of common
of global antibiotic resistance among Neisseria bacteria from various centres in Papua New Guinea. gonorrhoeae and Haemophilus ducreyi. Lancet Abstract in Programme and Abstracts of the Thirty- fourth Annual Medical Symposium of the Medical 11 Tapsall JW. Antibiotic resistance in Neisseria
Society of Papua New Guinea, Port Moresby, 7-11 gonorrhoeae. Clin Infect Dis 2005;41(Suppl 20 Van Dyck E, Meheus A, Piot P. Laboratory
12 Weisfuse IB. Gonorrhoea control and antimicrobial
diagnosis of sexually transmitted diseases. Geneva: resistance. Lancet 1998;351:928. 13 World Health Organization Regional Office for
21 Kugelman G, Tapsall JW, Goire N, Syrmis MW,
the Western Pacific. The gonococcal antimicrobial
Limnios A, Lambert SB, Nissen MD, Sloots TP,
surveillance programme (GASP) of the WHO Whiley DM. Simple, rapid, and inexpensive
Western Pacific Region: present trends. STI and detection of Neisseria gonorrhoeae resistance HIV/AIDS Surveillance Report 2002;17:13-15. 14 Pusahai-Riman P, Soepol N. A retrospective
mechanisms using heat-denatured isolates and assessment of antibiotic susceptibility pattern of SYBR green-based real-time PCR. Antimicrob Neisseria gonorrhoeae and prevalence rate of Agents Chemother 2009;53:4211-4216. gonorrhoea in Port Moresby General Hospital from 22 Vernel-Pauillac F, Merien F. A novel real-time
2005 to 2006. Pac J Med Sci 2008;5:82-90. duplex PCR assay for detecting penA and ponA 15 World Health Organization Regional Office for
genotypes in Neisseria gonorrhoeae: comparison South-East Asia. Laboratory Diagnosis of
with phenotypes determined by the E-test. Clin Gonorrhoea. WHO Regional Publication, South-

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