The epidemiology of Neisseria gonorrhoeae isolates in Dakar, Sénégal 1982-1986: antimicrobial resistance, auxotypes and plasmid profiles

Molecular Typing of Neisseria gonorrhoeae Isolates by Opa-Typing and Ribotyping in New Delhi, India

Control and preventive measures for gonococcal infections are based on precise epidemiological characteristics of N. gonorrhoeae isolates. In the present study the potential utility of opa-typing and ribotyping for molecular epidemiological study of consecutive gonococcal strains was determined. Sixty gonococcal isolates were subjected to ribotyping with two restriction enzymes, AvaII and HincII, and opa-typing with TaqI and HpaII for epidemiological characterization of gonococcal population. Ribotyping with AvaII yielded 6 ribotype patterns while twelve RFLP patterns were observed with HincII. Opa-typing of the 60 isolates revealed a total 54 opa-types, which 48 were unique and 6 formed clusters. Fifty-two opa-types were observed with TaqI-digested PCR product while opa-typing with HpaII demonstrated 54 opa-types. The opa-types from isolates that were epidemiologically unrelated were distinct, whereas those from the sexual contacts were identical. The results showed that opa-typing is highly useful for characterizing gonococcal strains from sexual contacts and has more discriminatory than ribotyping that could differentiate between gonococci of the same ribotype. The technique even with a single restriction enzyme has a high level of discrimination (99.9%) between epidemiologically unrelated isolates. In conclusion, the molecular methods such as opa-typing and ribotyping can be used for epidemiological characterization of gonococcal strains.

Treatment of sexually transmitted bacterial diseases in pregnant women

Testing for and treating sexually transmitted diseases (STDs) in pregnant women deserves special attention. Treatment possibilities are limited because of potential risks for the developing fetus, and because effects can differ in pregnant compared with non-pregnant women, re-infection may be missed because of the intrinsic delicacy of contact-tracing during pregnancy and because pregnant women are more reluctant to take the prescribed medication in its full dose, if at all. However, the devastating effects of some of these genital infections far outweigh any potential adverse effects of treatment. Although active syphilis has become a rarity in most Western countries, it is still prevalent in South America, Africa and South-East Asia. Benzathine benzylpenicillin (2.4 million units once or, safer, twice 7 days apart) is the treatment of choice, although patients with syphilis of longer standing require 3 weekly injections as well as extensive investigation into whether there has been any damage due to tertiary syphilis. Despite declining rates of gonorrhea, the relative rate of penicillinase-producing strains is increasing, especially in South-East Asia. The recommended treatment is intramuscular ceftriaxone (125 or 250 mg) or oral cefixime 400 mg. Despite good safety records after accidental use, fluoroquinolones are contraindicated during pregnancy. An alternative to a fluoroquinolone in pregnant women with combined gonorrhea and chlamydial infection is oral azithromycin 1 or 2 g. Azithromycin as a single 1 g dose is also preferable to a 7 day course of erythromycin 500 mg 4 times a day for patients with chlamydial infection. Eradication of Haemophilus ducreyi in patients with chancroid can also be achieved with these regimens or intramuscular ceftriaxone 250 mg. Trichomonas vaginalis, which is often seen as a co-infection, has been linked to an increased risk of preterm birth. Patients infected with this parasite should therefore received metronidazole 500 mg twice daily for 7 days as earlier fears of teratogenesis in humans have not been confirmed by recent data. Bacterial vaginosis is also associated with preterm delivery in certain risk groups, such as women with a history of preterm birth or of low maternal weight. Such an association is yet to be convincingly proven in other women. The current advice is to treat only women diagnosed with bacterial vaginosis who also present other risk factors for preterm delivery. The treatment of choice is oral metronidazole 1 g/day for 5 days. The possible reduction of preterm birth by vaginally applied metronidazole or clindamycin is still under investigation. In general, both test of cure and re-testing after several weeks are advisable in most pregnant patients with STDs, because partner notification and treatment are likely to be less efficient than outside pregnancy and the impact of inadequately treated or recurrent disease is greater because of the added risk to the fetus. Every diagnosis of an STD warrants a full screen for concomitant genital disease. Most ulcerative genital infections, as well as abnormal vaginal flora and bacterial vaginosis, increase the sexual transmission efficiency of HIV, necessitating even more stringent screening for and treating of STD during pregnancy.

Auxotypes, serovars, and trends of antimicrobial resistance of Neisseria gonorrhoeae in Kigali, Rwanda (1985-93)

OBJECTIVE

To investigate the in vitro antimicrobial susceptibility and the auxotype/serovar distribution of Neisseria gonorrhoeae in Kigali, Rwanda, during 1985-93.

METHODS

As part of a monitoring programme the in vitro susceptibility of 1604 isolates of N gonorrhoeae was determined by agar dilution. Auxo- and serotyping was performed on 1350 and 1313 isolates respectively.

RESULTS

The prevalence of penicillinase producing N gonorrhoeae (PPNG) remained stable at a rate of 39% during 1985-91 and increased to 61% in 1992-3. Chromosomal resistance to penicillin was common among non-PPNG and resistance to thiamphenicol and tetracycline was common among both PPNG and non-PPNG. High level, plasmid mediated resistance to tetracycline (TRNG) was observed for the first time at the end of 1989 and increased from 2% of the isolates in 1990 to 50% by 1993. A trend for increasing resistance to norfloxacin and ofloxacin was observed during 1985-90 but disappeared in 1991-93. Five isolates with high level resistance to norfloxacin (MIC 2 mg/l) were observed in 1990. Resistance to trimethoprim-sulphamethoxazole (TMP-SMZ) emerged at the end of 1990 and was observed among 10% of the isolates during 1991-3. All strains remained susceptible to ofloxacin, ciprofloxacin, spectinomycin, and ceftriaxone. Overall, 75% of the isolates were prototrophic or required proline for their growth and 62% belonged to serovars IA-6 and IB-1. The prevalence of serovar IB-4 increased strongly during the last 3 years of the study.

CONCLUSION

Resistance to penicillin, thiamphenicol, and tetracycline was common in N gonorrhoeae during 1985-1993. The rapid spread of TRNG after 1989 and the steep increase of PPNG during 1992-3 were the most striking facts of the study period. The auxotype and serovar distribution was comparable with findings from other African countries.

Antimicrobial susceptibility, auxotype and plasmid content of Neisseria gonorrhoeae in northern Tanzania: emergence of high level plasmid mediated tetracycline resistance

OBJECTIVE

To study the antimicrobial susceptibility, plasmid content, auxotype and serogroup of strains of Neisseria gonorrhoeae isolated from an urban population of STD clinic attenders in Northern Tanzania.

METHODS

The minimum inhibitory concentrations of nine common antimicrobial agents were measured by the agar dilution method against 130 strains of Neisseria gonorrhoeae isolated in a free government STD clinic in Mwanza town. The auxotype, plasmid content and serogroup of these strains were also determined by conventional techniques.

RESULTS

65 strains (50%) were penicillinase producers (PPNG), and 34 (26%) exhibited chromosomally mediated resistance to penicillin. Seven (5%) were sensitive to tetracycline; 78 (60%) showed intermediate levels of resistance, and 45 (35%) had high level plasmid mediated resistance (TRNG), all of which carried a 25.2 MDa plasmid. 79 strains (61%) showed decreased sensitivity to trimethoprim-sulphamethoxazole, and five (4%) were resistant to this agent. All isolates were fully sensitive to spectinomycin, azithromycin, cefotaxime, cefuroxime, norfloxacin and ciprofloxacin. One hundred and one strains (78%) were of type W11/111, 22 type W1, and seven cross reacting strains. The W1 strains were significantly more likely to be carrying plasmid mediated resistance to both penicillin and tetracycline. Six different auxotypes were present, the major type requiring proline. Plasmid profiles showed the presence of both the 3.2 MDa and the 4.4 MDa beta-lactamase encoding plasmids.

CONCLUSION

a high proportion of gonococcal isolates remain resistant to penicillin in this region, and most isolates are now also resistant to tetracycline, with the emergence of plasmic mediated tetracycline resistance. Trimethoprim-sulphonamide sensitivity is also decreasing. The population of strains is heterogeneous, and both African and Asian beta-lactamase encoding plasmids are present.

The dominance of a multiresistant strain of Neisseria gonorrhoeae among prostitutes and STD patients in The Gambia

OBJECTIVE

To study the epidemiology of antibiotic resistant strains of Neisseria gonorrhoeae from sexually transmitted disease clinics in The Gambia.

MATERIALS AND METHODS

One hundred and sixty five strains of N gonorrhoeae were tested for their antibiotic susceptibility, auxotype, serotype, and plasmid content.

RESULTS

Of the total population 84 (51%) were non-penicillinase producing (nonPPNG) and 81 (49%) penicillinase-producing N gonorrhoeae (PPNG). There were 16 serovars, five auxotypes and 33 auxotype/serovar (A/S) classes in the total population and the nonPPNG. Among PPNG only five serovars, two auxotypes and nine A/S classes were found. One A/S class predominated, NR/IB-7 (86 isolates), of which 66 (77%) were PPNG and the remainder were chromosomally-mediated resistant N gonorrhoeae (CMRNG). These strains also showed reduced susceptibility to ciprofloxacin, ceftriaxone and tetracycline and were evenly distributed among patient groups.

CONCLUSION

We have identified a relatively homogeneous gonococcal population with a core group of isolates exhibiting high levels of antibiotic resistance.

Antibiotic susceptibilities, serotypes and auxotypes of Neisseria gonorrhoeae isolated in New Zealand

OBJECTIVE

The aim of the study was to determine the distribution of auxotypes and serotypes and the prevalence of antibiotic resistance among New Zealand isolates of Neisseria gonorrhoeae.

MATERIALS AND METHODS

A total of 486 gonococci isolated in 1988 were auxotyped, serotyped, and tested for susceptibilities to ten antibiotics.

RESULTS

The gonococci were susceptible to all the antibiotics tested except penicillin and tetracycline. Eleven (2.2%) produced beta-lactamase, one (0.2%) showed chromosomal penicillin resistance, and 18 (3.7%) were resistant to a low-level of tetracycline. Most of the gonococci belonged to six auxotypes. The three predominant auxotypes were arginine-requiring (Arg-), non-requiring (NR), and arginine, hypoxanthine, uracil-requiring (AHU-). The majority of the isolates belonged to serogroup IB and to six serovars. The most prevalent serovars were IB-3 and IB-1. There was an association between penicillin susceptibility and auxotype or serovar among non-penicillinase producing N. gonorrhoeae (PPNG) isolates.

CONCLUSIONS

Antibiotic resistance, including penicillin resistance, remains uncommon among gonococci in New Zealand. Baselines have been established for future epidemiological studies using both auxotyping and serotyping.