|Year : 1992 | Volume
| Issue : 2 | Page : 89-92
Prevalent serogroups and antibiotic sensitivity of Neisseria gonorrhoeae
SK Aggarwal, M Deb, K Prakash, AK Sharma
S K Aggarwal
Source of Support: None, Conflict of Interest: None
One hundred and thirty two cases clinically labeled as acute gonorrhoea were investigated for gonococcal etiology. Smears were positive in 110 (83.3%) cases and among these N. gonorrhoeae could be identified in 102 (77.3%) cases by culture method. Strains were examined for serogrouping by monoclonal GC test which utilizes the principle of co-agglutination and detects the antigens of outer membrane protein. 96(94.1%) strains belonged to serogroup W II/III, showing it to be the major serogroup circulating in the community. The strains were tested for sensitivity against 7 antibiotics. The largest proportion (30.4%) of strains were resistant to penicillin (MIC>O. 125 IU/ml). Resistance to cotrimoxazole, erythromycin, cephalaxin and tetracycline was noted as 18.6, 17.6, 7.8 and 5.8 percent respectively. Strains showing resistance concurrently to two or more drugs were observed. All restrains were sensitive to gentamicin and norfloxacin. None of the strains was penicillinase producer.
Keywords: Neisseria gonorrhoeae, Serogroups, Antibiotic sensitivity
|How to cite this article:|
Aggarwal S K, Deb M, Prakash K, Sharma A K. Prevalent serogroups and antibiotic sensitivity of Neisseria gonorrhoeae. Indian J Dermatol Venereol Leprol 1992;58:89-92
|How to cite this URL:|
Aggarwal S K, Deb M, Prakash K, Sharma A K. Prevalent serogroups and antibiotic sensitivity of Neisseria gonorrhoeae. Indian J Dermatol Venereol Leprol [serial online] 1992 [cited 2020 Apr 6];58:89-92. Available from: http://www.ijdvl.com/text.asp?1992/58/2/89/3758
| Introduction|| |
Gonococci can be divided into two major (WI & WIl) and one minor (WIII) serogroup by coagglutination (COA). However, more than 1 reagent are necessary to classify all strains of gonococci into a given serogroup, indicating antigenic heterogeneity . In the last several years an intense research effort has been directed towards characterizing the surface components of N. gonorrhoeae. Goals of this research have included the development of a useful serotyping system as well as an understanding of the pathogenesis and epidemiology of the disease induced by these bacteria. Certain serogroups can be correlated with such clinically important characteristics as resistance to killing by normal human serum, ability to cause disseminated gonococcal infections, auxotrophy and sensitivity to antibiotics. 
N gonorrhoeae is generally sensitive to a wide range of antimicrobial drugs but a certain proportion of strains have developed resistance to drugs which have been most commonly used in therapy. Penicillin still remains the drug of choice in treatment of acute uncomplicated gonococcal infections, though therapeutic failures with the drug are becoming more common.  The problem has been further compounded by the appearance of penicillinase producing strains of N gonorrhoeae (PPNG). Such strains have also been reported from various parts of India in the recent past. 
This study was undertaken to obtain an insight into the antibiotic sensitivity patterns of N gonorrhoeae isolated in and around Delhi and distribution of serogroups as detected by COA test.
| Materials and Methods|| |
One hundred and thirty two patients clinically diagnosed as acute gonococcal urethritis, at venereal disease clinic of Dr Ram Manohar Lohia Hospital, New Delhi, comprised the study group. The urethral exudate was collected in duplicate with sterile swabs. Specimens were examined for presence of gram negative diplococci and were inoculated immediately on chocolate agar and Thayer Martin media with vancomycin, colistin, nystatin and trimethoprim (VCNT vials, Difco). Plates were incubated at 36 ° C for 48 hrs in candle jar. The organisms were identified by conventional methods. 
Serogrouping : Serogrouping using the principle of COA, was performed by commercially available reagents (Phadebact R monoclonal GC Test - Pharmacia diagnostics, Uppsala, Sweden). Briefly, one drop of reagent was mixed with one drop of boiled and cooled suspension of the gonococcal strain under investigation. Both serogroups were tested simultaneously. Suspension mixture was observed for 1 min before being reported. Control procedures as recommended by the manufacturer were adopted.
Antimicrobial sensitivity and penicillinase production : Sensitivity to antibiotics, namely, cephalexin, cotrimoxazole, erythromycin, gentamicin, norfloxacin, penicillin and tetracycline was tested by disc diffusion method. ,
Susceptibility to penicillin was further tested by determination of MIC values by standard agar dilution method using  sub concentrations, ranging from 0.003 IU/ml to 1.0. IU/ml of benzyl penicillin.  A strain was regarded resistant if MIC was > 0.125 IU/ml of benzyl penicillin.  Rapid iodometric test was used for detection of penicillinase production.  A local penicillinase producing strain of staphylococcus aureus and local penicillin sensitive strain of N gonorrhoeae were included as control.
| Results|| |
One hundred and ten samples showed presence of polymorphonuclear leukocytes and gram negative diplococci. Out of these, 102 strains were isolated and identified as N gonorrhoeae.
On serogrouping 100 (98%) showed a positive reaction with W II / III of which 4 (3.9%) strains showed a positive reaction with WI also. Only 2 (1.9%) strains belonged to serogroup WI. 25 strains in serogroup W 11 / III were resistant to penicillin (MIC > 0.125 IU/ml). The 4 strains belonging to W I+W II / III serogroup and 2 strains of W I serogroup had MIC levels > 0.125 IU/ml of benzyl penicillin. Thus a total of 31 (30.4%) strains were shown to be resistant to penicillin.
Penicillinase was not produced by any of these strains.
The resistance to other antibiotics, namely cotrimoxazole, erythromycin, cephalosporin and tetracycline was noted at 18.6, 17.6, 7.8 and 5.8 percent of the strains respectively. Strains resistant concurrently to more than one antibiotic were also observed [Table - 1].
All strains were sensitive to gentamicin and norfloxacin.
| Comments|| |
A provisional diagnosis of gonorrhoea could be made at OPD level by examination of gram stained smears of pus/exudate from the lesion. The smear and culture positivity rates in the present study were 83.4 percent and 77.2 percent respectively.
All the isolated strains showed a positive coagglutination by Phadebact Monoclonal GC test within 1 minute. Thus a 100 percent agreement of COA test was observed with conventional method of isolation and identification. As many as 96 (94.1%) strains were shown to belong to serogroup W 11/111, identifying it to be the major serogroup In circulation. These results compare well with those of other workers. 
The positive reaction in both the reagents was seen in 4 cases, which was presumably due to double infection of N gonorrhoeae belonging to group W I and W II / III, only 2 strains belonged to serogroup W I.
The testing of antibiotic sensitivity Is becoming increasingly necessary in gonorrhoea since the organism is becoming resistant to penicillin. A total of 30.4 percent strains were shown to have MIC > 0.125 IU/ml of benzyl penicillin in the present study, the highest level of MIC observed being 0.5 I.U./ml.
None of the patients was found to be suffering from PPNG infection. While it is true that PPNG strains have been reported from several parts of India, overall reports of incidence has been found to be very low. ,,, The general suspicion, however, is that rather than actual low incidence, this suggests imperfection in the data, with possible reasons for this, as discussed by other workers, being : non reporting of venereal disease in general, poor investigative facilities for culture of gonococci in most centres and treatment of urethritis patients without resorting to culture for gonococci.  Even if true, the relative absence of PPNG strains may be an interim phase only in our country, with these strains becoming established when the proportion of resistant strains reaches the level of 90 percent or more as in . Thailand.  However, extensive studies carried out in large cross section of the population will only be able to give a definite assessment of the prevalence or otherwise of PPNG strains. In addition, infection acquired from abroad poses a serious threat of introduction of resistant strains. 
Wide variations in the levels of resistance to antimicrobial agents other than penicillin was observed in this study as have been reported by others , and the results are comparable to the observations made in the present study.
It may be concluded that coagglutination test, which is a quick, specific, simple procedure that can be performed in clinical laboratories, helps in early diagnosis. Such simple diagnostic confirmation is adequate for the results to be useful in clinical practice. In view of the changing patterns of drug sensitivity regular monitoring of antimicrobial susceptibility has become necessary. It was observed that gentamicin and norfloxacin may continue to be promising drugs for treatment of gonorrhoea so long as their use does not become indiscriminate.
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[Table - 1]