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Evolution of Neisseria gonorrhoeae drug susceptibility in Buenos Aires, Argentina, 1985–99
  1. Angela Famiglietti1,
  2. S D Garcia1,
  3. C A de Mier1,
  4. R Casco2,
  5. L Belli2,
  6. F Marcenac3,
  7. C Vay3,
  8. R A de Torres4
  1. 1Clinical Microbiology Division, Department of Clinical Biochemistry, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Argentina
  2. 2STD Service, Faculty of Medicine, Hospital Nacional de Clínicas José de San Martín, Universidad de Buenos Aires
  3. 3Clinical Microbiology Division, Department of Clinical Chemistry, Faculty of Pharmacy and Biochemistry, University of Buenos Aires
  4. 4Faculty of Pharmacy and Biochemistry, University of Buenos Aires
  1. Dr R A de Torres, 1113 Ciudad de Buenos Aires, Facultad de Farmacia y Bioquimica, Junin 956 4 Piso, Argentina detorres{at}

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Demographic data

Buenos Aires (Argentina) is an international port city of three million people surrounded by greater Buenos Aires, with a core population of 10 million people.

The STD service of the Hospital Nacional de Cllínicas, University of Buenos Aires (HNC) deals with 80% patients from the city and 20% from the suburban areas. A total of 33 316 symptomatic patients (27 458 men and 5858 women) were studied from 1985–99.1 Patients attended under the standard regulations of HNC primary care protocol, and so no additional written informed consent was required.


Neisseria gonorrhoeae (NG) was investigated by direct Gram stain microscopy and by culture in Columbia agar supplemented with 5% blood and 1.5% protease peptone No 3 and in Thayer-Martin modified agar.2

NG was identified by positive oxidase and catalase tests, followed by carbohydrate biochemical tests after 72 hours' incubation at 37°C without hypercapnia atmosphere.

β-Lactamase was studied using nitrocefin. The minimal inhibitory concentration (MIC) was measured by agar dilution technique, and NCCLS guidelines were apply for isolate categorisation.3


General gonorrhoea rates declined from a mean of 14.8% (1985–91) to 4.4% in 1992. Between 1992 and 1999 (mean 4.9%) the rate became stable.

The incidence of NG (1998–9) in men who have sex with men (MSM) was 15.7% compared with 5.9% in heterosexual men (odds ratio 294 (221<OR<3.92) p=000, Yates's correction).

Between 1985 and 1999, 83 extragenital gonococci were isolated (rectum 70 and throat 13). None of the throat isolates was PPNG and only 3% were CMRNG. Strains isolated from the rectum were 14% PPNG and 46% CMRG, which is highly significant.

General NG sensitivity evolution (table 1), is presented in three periods: 1985–6, 1988, and 1995–9.

Table 1

Susceptibility to antimicrobial agents in isolates of N gonorrhoeae

At present we have not detected resistance to an extended spectrum of cephalosporins (1995–9). Only one strain showing decreased susceptibility to ciprofloxacin and ofloxacin was found (MIC = 0.5 μg/ml) in 1996. From 1985 to 1999 more than 50% of isolates were resistant to penicillin with changes in PPNG (decreasing) and CMRNG (increasing).


Gonorrhoea decreased drastically between 1991 and 1992 in heterosexual, MSM, and also in women, in Buenos Aires. A great deal of information directed at AIDS prevention has been developed. Unfortunately, there is no clear demonstration of a significant improvement in safe sexual behaviour, so the decrease in the incidence of gonorrhoea must be explained by other factors, most probably access to very efficient treatment.4

It is necessary to develop a geographical targeted intervention in order to identify the residual clusters and to reduce incidence in MSM. Also the sensitivity of the rectal isolates of NG shows a very peculiar profile.5

We have increased the drug sensitivity surveillance in order to detect any potential appearance of NG with decreased susceptibility to the fluoroquinolones, and/or to the extended spectrum cephalosporin resistance, absent in this region till now.


This work was supported by a grant (B22 1998–2000) of Ciencia y Tecnologia, Universidad de Buenois Aires.

Contributors: AF conducted the laboratory group for microbiology and drug sensitivity for Neisseria gonorrhoeae; SDG, CAdM, and CV assisted in the research; RC and LB were involved with the primary care; FM was responsible for quality control; RAdT analysed the data, epidemiology of STD, and prepared the manuscript. He is a member of the Consejo Nacional de Investigaciones Científicas y Tecnicas (CONICET).