Surveillance of antibiotic resistance in Neisseria gonorrhoeae in the WHO Western Pacific Region, 1999

This report published in Communicable Diseases Intelligence Volume 24, No 9, September 2000 contains information on a long-term programme of surveillance of antimicrobial resistance in Neisseria gonorrhoeae isolated in the World Health Organization's Western Pacific Region Gonococcal Antimicrobial Surveillance Programme.

Page last updated: 09 October 2000

A print friendly PDF version is available from this Communicable Diseases Intelligence issue's table of contents.


The WHO Western Pacific Region Gonococcal Antimicrobial Surveillance Programme

Corresponding author: Associate Professor John W Tapsall, WHO Collaborating Centre for STD and HIV, Department of Microbiology, The Prince of Wales Hospital, Randwick, NSW, Australia 2031. Telephone: + 61 2 9382 9079. Fax + 61 2 9398 4275. E-mail: j.tapsall@unsw.edu.au


Introduction | Methods | Results and discussion | Acknowledgements | References

Abstract

A long-term programme of surveillance of antimicrobial resistance in Neisseria gonorrhoeae isolated in the World Health Organization's Western Pacific Region Gonococcal Antimicrobial Surveillance Programme (WHO WPR GASP) continued in 1999. Over 10,000 gonococci were examined in 18 focal centres. Resistance to the quinolones and penicillins was already high in many parts of the Western Pacific Region and increased further in most centres, the exceptions being a number of Pacific Island States. Although resistance to the later generation cephalosporins was absent, and that to spectinomycin infrequent, options for effective treatment of gonorrhoea in the Western Pacific Region continue to be limited. Commun Dis Intell 2000;24:269-271.

Introduction

Neisseria gonorrhoeae is, with Haemophilus ducreyi, one of the few aetiological bacterial agents of sexually transmitted infection (STI) where antimicrobial resistance (AMR) seriously compromises disease control. Additionally AMR in gonococci, by preventing effective treatment of individuals, increases the rate of complications and morbidity associated with gonococcal disease. One further deleterious consequence of gonorrhoea is the amplification of the rate of transmission of HIV that occurs in its presence. However, effective treatment of gonorrhoea removes this effect. It is therefore important to ensure that gonococcal disease is properly treated, and this in turn depends to a significant degree on having relevant data on AMR patterns to guide selection of treatment regimens.

AMR in gonococci may arise and spread rapidly. The World Health Organization (WHO) Western Pacific Region (WPR) includes countries with high rates of STIs and where different forms of AMR have arisen in the past. Gonococci resistant to the penicillins, spectinomycin and, more recently, the quinolone antibiotics had their origins in countries in the WPR. The potential for spread of AMR gonococci beyond regional confines is also well established so that disease acquired in one setting may present in another. There are thus multiple reasons to ascertain the prevalence and distribution of AMR in gonococci and modify treatment regimens accordingly. The WHO WPR Gonococcal Antimicrobial Surveillance Programme (GASP) has monitored AMR in gonococci in the region since 1992 and results have been published in Communicable Diseases Intelligence.1,2 This communication provides an analysis of surveillance of AMR in N. gonorrhoeae in 18 countries in the WHO WPR in 1999.

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Methods

The methods used by the WHO WPR GASP were published in 19973 and provide full details of the source of isolates, sample populations, laboratory test methods and quality assurance programs used to generate data. These methods were unaltered in 1999. Most isolates were collected from symptomatic STD clinic patients. As a guide to the interpretation of the following data, a WHO expert committee has recommended that treatment regimens be altered once resistance to a particular antibiotic reaches 5 per cent.4

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Results and Discussion

About 10,600 gonococcal isolates were examined in 18 participating countries (listed in the Acknowledgements) in 1999.

Penicillins

Resistance to the penicillins remained widespread by both chromosomal and plasmid-mediated mechanisms. Table 1 provides details of chromosomally mediated resistance in N. gonorrhoeae (CMRNG), penicillinase-producing N. gonorrhoeae (PPNG) and/or total penicillin resistance in 18 WPR countries in 1999. Very high rates of all penicillin resistance (CMRNG + PPNG) were recorded in Korea (95%), the Philippines (94%), China (88%), Hong Kong SAR (73%), Brunei (67%), Vietnam (66%), Singapore (56%) and Mongolia (48%). Resistance to the penicillins in these countries in 1999 approximated that found in 1998. Of interest were the low rates of penicillin resistance found in some Pacific Island States. The Solomon Islands and Vanuatu had no penicillin resistant strains in 1999 and in New Caledonia (4%), Fiji (4.8%) and Tonga (5%,) rates were considerably lower than those observed in other parts of the region. The exception to this observation was Papua New Guinea where penicillin resistance was of the order of 59 per cent, equally distributable between PPNG and CMRNG. The other participants submitting data in 1999 (Australia, Japan, Malaysia and New Zealand) had rates of penicillin resistance between 8 and 38 per cent.

Table 1. Penicillin sensitivity of strains of Neisseria gonorrhoeae isolated in 18 countries in the WHO WPR1 in 1999

Country
No. tested PPNG2 CMRNG3 All penicillin- resistant
No. % No. % No. %
Australia
3,658
269
7.4
525
14.3
794
21.7
Brunei
64
 
 
 
 
43
67.0
China
571
127
21.5
338
57.1
465
88.6
Fiji
860
17
1.9
24
2.8
41
4.7
Hong Kong SAR
2,482
233
9.4
1,576
63.5
1,809
72.9
Japan
246
3
1.2
36
14.8
39
16.0
Korea
86
72
84.0
10
12.0
82
95.0
Malaysia
54
13/44
29.0
5
9.3
18
38.3
Mongolia
56
10
17.8
17
30.4
27
48.2
New Caledonia
53
 
 
 
 
2
3.8
New Zealand
638
18
2.8
34
5.3
52
8.1
Papua New Guinea
343
73/253
28.8
103
30.0
 
58.8
Philippines
313
294
94.0
0
0.0
294
94.0
Singapore
768
399
51.9
31
4.0
430
55.9
Solomon Islands
21
0
0.0
0
0.0
0
0.0
Tonga
39
1
2.5
1
2.5
2
5.0
Vanuatu
129
0
0.0
0
0.0
0
0.0
Vietnam
194
99
51.0
28
14.4
127
65.5

1. World Health Organization: Western Pacific Region.
2. PPNG = penicillinase-producing N. gonorrhoeae.
3. CMRNG = chromosomally mediated resistance in N. gonorrhoeae.


Quinolones

Resistance to the quinolone antibiotics has become a major problem in parts of the WPR in recent years and this situation deteriorated further in 1999. Data from 15 WPR countries are shown in Table 2 and allow division of quinolone-resistant strains (QRNG) into 'less susceptible' and 'resistant' categories on the basis of minimal inhibitory concentration (MIC) determinations.3 Twelve of 15 WPR countries detected QRNG in 1999. High proportions of QRNG were detected in Hong Kong, China, Japan and the Philippines, maintaining a situation observed in previous reports. In Hong Kong the percentage of 'resistant' QRNG increased from about 50 per cent in 1998 to about 66 per cent in 1999. A similar shift to higher MICs in Japan saw the proportion of 'resistant' QRNG there increase from 3 per cent in 19982 to about 23 per cent in 1999. The proportion of QRNG also increased significantly in Vietnam in 1999 to about 50 per cent from 17 per cent in 1998. Most of the QRNG in Vietnam were in the higher MIC range. Singapore recorded an increase in resistant strains from 7 per cent in 1998 to 17 per cent in 1999. In both Korea and Australia there were increases in the percentage of QRNG in the less susceptible range. In Korea these increased from about 50 per cent to 71 per cent and in Australia from 2 per cent to 14 per cent as a result of spread of QRNG in homosexually active males. Mongolia reported QRNG data for the first time and about one third of isolates exhibited some form of quinolone resistance; 25 per cent of them had high level resistance. About 17 per cent of strains from Brunei, 3.5 per cent from New Zealand and 1.8 per cent from Papua New Guinea were QRNG. No QRNG were found in Malaysia, New Caledonia or the Solomon Islands in 1999. Top of page

Table 2. Quinolone resistance in strains of Neisseria gonorrhoeae isolated in 15 countries in the WHO WPR1 in 1999

Country
No. tested Less susceptible Resistant
No. % No. %
Australia
3,658
500
13.7
128
3.5
Brunei
53
4
7.5
5
9.4
China
591
131
22.1
332
52.8
Hong Kong SAR
2482
697
28.1
1653
66.6
Japan
246
80
32.5
56
22.8
Korea
86
61
71.0
14
16.0
Malaysia
54
0
0.0
0
0.0
Mongolia
56
5
8.9
14
25.0
New Caledonia
53
0
0.0
0
0.0
New Zealand
638
8
1.3
14
2.2
Papua New Guinea
343
1
0.3
5
1.5
Philippines
313
8
2.5
191
61.0
Singapore
768
37
4.8
131
17.0
Solomon Islands
21
0
0.0
0
0.0
Vietnam
194
27
13.9
69
35.6

1. World Health Organization: Western Pacific Region.


Cephalosporins

There were no isolates resistant to the third generation cephalosporin agents reported in the WPR GASP survey that examined about 7,250 gonococci from 16 of the participating countries.

Spectinomycin

Only two isolates, one each in Malaysia and Papua New Guinea were resistant to spectinomycin amongst about 7,250 gonococci examined in 16 of the participating countries in 1999. Only very occasional strains resistant to this injectable antibiotic have been found in recent WPR surveys.

Tetracyclines

Although tetracyclines are not a recommended treatment for gonorrhoea, these agents are widely used and readily available in the WPR. One particular type of resistance is common in parts of the WPR; this is plasmid-mediated and gives rise to high-level tetracycline resistant N. gonorrhoeae (TRNG). About 6,900 gonococci were examined for high-level tetracycline resistance in 12 of the WPR countries in 1999 (Table 3). TRNG were again prominent in Malaysia, Singapore, Vietnam and the Solomon Islands with TRNG rates between 40 and 74 per cent. Rates below 10 per cent were seen in Australia, New Zealand and the Philippines. The TRNG rate increased in China from around 3 per cent in 1998 to nearly 15 per cent in 1999. A similar rate was observed in Papua New Guinea. TRNG were not detected in isolates from Korea, Mongolia and Tonga.

The data recorded in 1999 continue trends noted over several years. Resistance to the penicillins remains widespread, although some island States have low rates of resistance. The effectiveness of the quinolone group of antibiotics continues to decrease and their use in many countries should be discontinued because of the levels of resistance present. However, although alternative therapies are available, their cost limits their use in some settings.

Table 3. High-level tetracycline resistance in strains of Neisseria gonorrhoeae isolated in 12 countries in the WHO WPR1 in 1999.

Country
No. Tested
No. TRNG2
% TRNG
Australia 3,658 288 7.8
China 591 86 14.5
Korea 86 0 0.0
Malaysia 54 32 59.0
Mongolia 27 0 0.0
Papua New Guinea 343 54 15.7
New Zealand 638 8 1.3
Philippines 313 16 5.1
Singapore 768 566 73.7
Solomon Islands 21 12 57.0
Tonga 39 0 0.0
Vietnam 195 79 40.5

1. World Health Organization: Western Pacific Region.
2. TRNG = tetracycline-resistant N. gonorrhoeae.


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Acknowledgements

The following members of the WHO Western Pacific Region Gonococcal Antimicrobial Surveillance Programme supplied data in 1999 for the WPR GASP:

Members of the Australian gonococcal surveillance program throughout Australia; Nora'Alia Rahim, Brunei; Ye Shunzhang and Su Xiaohong, Nanjing, China; Sainimere Bavoro, Suva, Fiji; K M Kam, Hong Kong; Toshiro Kuroki, Yokohama and Masatoshi Tanaka, Fukuoka, Japan; K Lee and Y Chong, Seoul, Korea; Rohani Yasin Malaysia; Erdenechimeg Lkhamsuren, Ulaanbaatar, Mongolia; B Garin, Noumea, New Caledonia; M Brett, Wellington and M Brokenshire, Auckland, New Zealand; M V Hombhanje, Port Moresby, Papua New Guinea; C C Carlos, Manila, Philippines; Cecilia Ngan and A E Ling, Singapore; A Darcy, Solomon Islands; Ane Tone Ika, Nuku'alofa, Tonga; H   Taleo Vanuatu; Le Thi Phuong, Hanoi, Vietnam.

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References

1. WHO Western Pacific Region Gonococcal Surveillance Programme. World Health Organization Western Pacific Region Gonococcal surveillance, 1992 annual report. Commun Dis Intell 1994;18:61-63.

2. The WHO Western Pacific Gonococcal Antimicrobial Surveillance Programme. Surveillance of antibiotic resistance in Neisseria gonorrhoeae in the WHO Western Pacific Region, 1998. Commun Dis Intell 2000;24:1-4.

3. WHO Western Pacific Region Gonococcal Antimicrobial Surveillance Programme. Surveillance of antibiotic susceptibility of Neisseria gonorrhoeae in the WHO Western Pacific Region 1992-4. Genitourin Med 1997;73:355-361.

4. Anonymous. Management of sexually transmitted diseases. World Health Organization 1997. Document WHO/GPA/ TEM94.1 Rev.1 p 37.


This article was published in Communicable Diseases Intelligence Volume 24, No 9, September 2000.

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