Tetracycline-resistant Neisseria gonorrhoeae. Characteristics of patients and isolates at a London Genitourinary Medicine Clinic.
OBJECTIVE
To compare auxotypes, serovars, and antibiograms of tetracycline-resistant Neisseria gonorrhoeae (TRNG) and non-TRNG isolated from patients attending an East London Genitourinary Medicine (GUM) Clinic. To obtain plasmid profiles for penicillinase-producing gonococci (PPNG) as well as presumptive TRNG. To identify differences in patient characteristics for the TRNG and non-TRNG patient groups.


METHODS
Gonococcal isolates were collected from 400 patients attending the GUM clinic at the Royal London Hospital GUM Clinic over a 1-year period. Isolates (378) were tested for susceptibility to various antibiotics, auxotyped, and serotyped. Plasmid profiles were obtained for PPNG and isolates exhibiting high-level tetracycline resistance (TRNG). The presence of the tet M determinant was confirmed using the polymerase chain reaction (PCR). The PCR product was digested with the restriction endonuclease (RE) Hpa II and electrophoresed on a 2.5% agarose gel to determine an "RE pattern." Patient data were collected by retrospective case-note review.


RESULTS
TRNG (n = 42) accounted for 11% of the 378 isolates tested, and the remaining 336 (89%) isolates were non-TRNG. Non-requiring auxotrophy and P1B-2 serovar expression occurred more frequently among TRNG. PPNG accounted for 31% of TRNG and 5% of non-TRNG. Chromosomal resistance to penicillin (CMRNG) was absent among TRNG but accounted for 11% of non-TRNG. One TRNG isolate showed decreased susceptibility to ciprofloxacin (MIC 0.25 mg/l). All isolates were sensitive to cefotaxime, cefixime, spectinomycin, and azithromycin. All TRNG possessed the 25.2 MDa plasmid and produced a PCR product of appropriate size after tet M gene sequence amplification. RE digests of the PCR product gave a single pattern. None of the TRNG in contrast to 18% of the non-TRNG were acquired homosexually. Ethnic distribution differed between the patients with TRNG and patients without non-TRNG (Afro-Caribbean 81% versus 58%; white 19% versus 36%). Most TRNG were acquired in the United Kingdom.


CONCLUSIONS
TRNG differ from the non-TRNG in their auxotype and serovar distribution. PPNG are more common among the TRNG isolates, whereas CMRNG appear absent. TRNG are isolated more commonly from Afro-Caribbean patients and were not represented among homosexually acquired isolates.
Lewis
D A
DA
Department of Medical Microbiology, Royal London Hospital, United Kingdom.
Ison
C A
CA
Forster
G E
GE
Goh
B T
BT
D000293:Adolescent; D000328:Adult; D005260:Female; D006069:Gonorrhea / Q000382:microbiology* / Q000635:transmission; D006801:Humans; D008131:London; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital; D011815:R Factors; D012703:Serotyping; D012725:Sexual Behavior; D013753:Tetracycline Resistance