Isolation of Neisseria gonorrhoeae on selective and nonselective media in a sexually transmitted disease clinic

Abstract

To assess the practical significance of reported increases in the prevalence of vancomycin-susceptible strains of Neisseria gonorrhoeae on isolation of this organism, antibiotic-free chocolate agar (CA), modified Thayer-Martin medium (MTM), and a vancomycin-free selective medium (VFSM) were compared in a sexually transmitted disease clinic. Among 326 cervical gonococcal infections detected in a comparison of CA with MTM, 92.0% were detected on CA, compared with 98.2% on MTM (P < 0.001). Similarly, among 306 cervical infections detected in a comparison of MTM and VFSM, 95.8% of infections were detected with VFSM, compared with 98.4% for MTM (P = 0.10). For 1,632 urethral infections in men, all three media were equivalent, with none detecting fewer than 98% of the infections. Compared with a single inoculation, dual inoculation of MTM increased the diagnostic yield by 1.5% for 206 urethral infections and 2.4% for 83 cervical infections. In our clinic population, MTM is superior to CA or VFSM for the diagnosis of genital gonococcal infections, especially in women. The increased yield that accrued from inoculation of both MTM and either of the other media was not sufficiently high to warrant routine use of this practice in our clinic.

Evaluation of ligase chain reaction for use with urine for identification of Neisseria gonorrhoeae in females attending a sexually transmitted disease clinic

“…This constraint may act as a disincentive for patients to seek screening and serve to limit testing to environments equipped for performing pelvic examinations. In addition, screening for gonorrhea with single cervical swab cultures is not 100% sensitive, because of multiple factors which include sampling errors, inhibition of growth by components of selective culture media, and loss of viability during specimen transport (2,5,6,11). The high degree of sensitivity of nucleic acid amplification tests for microbiologic diagnosis and recent studies demonstrating the utility of ligase chain reaction (LCR) testing of both urine and swab specimens for the sensitive and specific diagnosis of Chlamydia trachomatis infections suggested to us that urine might serve as an appropriate substitute for swab specimens in LCR testing for the diagnosis of gonorrhea in women (3,8,19).…”

Comparison of GC-Lect and modified Thayer-Martin media for isolation of Neisseria gonorrhoeae

“…In addition, because of geographic variability in gonococcal strain populations and antimicrobial susceptibilities, there may also be geographic variability in the utility of different selective media (6,7,16). Parallel use of both selective and nonselective media might optimize isolation rates of N. gonorrhoeae; however, this practice would substantially increase costs in materials and personnel time in both the clinic and the laboratory and has been demonstrated to only slightly increase culture yield (1).…”

“…Despite the utility of currently available selective media for gonorrhea culture diagnosis, overgrowth of other microorganisms still occasionally occurs, and growth of some gonococci is inhibited by the antibiotic concentrations present in selective media. The vancomycin concentrations in some selective media have been reported to inhibit growth of 0.3 to 30% of gonococcal strains (1,2,14,18,23). The presence of other microorganisms may also hinder recovery of N. gonorrhoeae on primary culture; substances produced by organisms such as Staphylococcus epidermidis, Candida albicans, members of the family Enterobacteriaceae, and anaerobic bacteria may inhibit growth of N. gonorrhoeae (8,10,12).…”

Σεξουαλικώς Μεταδιδόμενα Παθογόνα Σε Γόνιμες Και Υπογόνιμες Γυναίκες Αναπαραγωγικής Ηλικίας

“…Ο καταλληλότερος συνδυασµός αντιβιοτικών περιλαµβάνει βανκοµυκίνη, για την αναστολή των Gram θετικών βακτηρίων, κολιστίνη για τα Gram-αρνητικά βακτήρια, τριµεθοπρίµη για να παρεµποδίζει τον ερπυσµό των Proteus sp. και νυστατίνη ή αµφοτερικίνη για την αναστολή των µυκήτων(Evangelista et al 1993, Morello et al 1985, Bonin et al 1984. Μετά την επώαση, ακολουθούν οι δοκιµασίες ταυτοποίησης της N. gonorrhoeae.…”

“…Στο φαρυγγικό και ορθικό η χρώση είναι αναξιόπιστη λόγω παρουσίας σαπροφυτικών ναϊσσεριών. Η παρουσία γονοκόκκων και πυοσφαιρίων standard) για τη διάγνωση της νόσου για δύο λόγους: (α) την ευαισθησία της (70-95%), παρά το ότι οι µοριακές δοκιµασίες αναζήτησης νουκλεινικού οξέος (PCR, LCR, TMA) επιτυγχάνουν ήδη παρόµοια ποσοστά ευαισθησίας, και (β) την ειδικότητά της (100%)(Bonin 1984. Η ευαισθησία της καλλιέργειας για την ανίχνευση του γονόκοκκου εξαρτάται σε µεγάλο βαθµό από το είδος των δειγµάτων (θέση και τρόπος δειγµατοληψίας), τα υλικά µεταφοράς, τις συνθήκες επώασης και την ταυτοποίηση των αποικιών που αποµονώθηκαν.…”