TYPING BY SEROVAR, ANTIBIOGRAM, PLASMID CONTENT, RIBOPROBING, AND ISOENZYME TYPING TO DETERMINE WHETHER NEISSERIA-GONORRHOEAE ISOLATES REQUIRING PROLINE, CITRULLINE, AND URACIL FOR GROWTH ARE CLONAL
Lk. Ng et Jar. Dillon, TYPING BY SEROVAR, ANTIBIOGRAM, PLASMID CONTENT, RIBOPROBING, AND ISOENZYME TYPING TO DETERMINE WHETHER NEISSERIA-GONORRHOEAE ISOLATES REQUIRING PROLINE, CITRULLINE, AND URACIL FOR GROWTH ARE CLONAL, Journal of clinical microbiology, 31(6), 1993, pp. 1555-1561
Neisseria gonorrhoeae isolates requiring proline, citrulline, and urac
il for growth (PCU-) have homogeneous phenotypes; most are plasmid-fre
e, belong to few serovars, and are significantly associated with inter
mediate levels of susceptibility to penicillin, tetracycline, erythrom
ycin, and cefoxitin. Because of their lack of variation by these crite
ria, molecular typing methods, ribotyping (restriction fragment length
polymorphism [RFLP] of rRNA genes), and multilocus enzyme electrophor
esis were explored as tools for further distinguishing PCU- isolates.
By ribotyping, selected PCU- isolates could be separated into four gro
ups on the basis of the hybridization patterns (RFLPs) of SmaI- and Av
aII-digested DNA with probes containing rRNA sequences. Most of the is
olates (18 of 23 isolates) belonged to a single RFLP (group I). One is
olate each was in groups II and IV, and three isolates were in group I
II. All isolates except one, isolate NS791, had similar multilocus enz
yme electrophoresis patterns. Strain NS791 was unusual in that it cont
ained a variant cryptic plasmid with an insert in the 0.46-kb MspI-Hin
fI fragment of the 4.2-kb plasmid, it was the only isolate belonging t
o RFLP group IV, and it differed in its multilocus enzyme electrophore
sis pattern, having different mobilities for glyceraldehyde phosphate
dehydrogenase, phosphoglucose isomerase, 6-phosphogluconate dehydrogen
ase, and glutamate dehydrogenase. Serovars of PCU- isolates appeared t
o be more indicative of strain divergence than RFLP or isoenzyme typin
g. Multilocus enzyme electrophoresis indicated that PCU- isolates are
clonal.