Detection of tetQ and ermF antibiotic resistance genes in Prevotella and Porphyromonas isolates from clinical specimens and resident microbiota of humans
Ar. Arzese et al., Detection of tetQ and ermF antibiotic resistance genes in Prevotella and Porphyromonas isolates from clinical specimens and resident microbiota of humans, J ANTIMICRO, 45(5), 2000, pp. 577-582
Gram-negative anaerobes belonging to the genera Fusobacterium, Prevotella a
nd Porphyromonas were investigated for the presence of tetQ and ermF, which
have been shown to be spread by conjugal elements. One hundred isolates fr
om either sites of infection or various body sites in healthy subjects were
studied. PCR was used to detect tetQ, and DNA-DNA hybridization studies on
EcoRI chromosomal digests were undertaken to detect the presence of tetQ a
nd ermF. Antibiotic sensitivity assays were performed on selected isolates
to detect tetracycline, erythromycin and penicillin resistance. Twenty Fuso
bacterium isolates lacked tetQ, and were tetracycline sensitive. Twenty per
cent of Prevotella spp, isolates both from clinical specimens and from hea
lthy subjects were found to possess tetQ. Of 20 Porphyromonas isolates test
ed, one (Porphyromonas levii) from a case of bacterial vaginosis was shown
to possess tetQ in the chromosome. The presence of tetQ was always associat
ed with tetracycline resistance. Four isolates of Prevotella melaninogenica
and one isolate of Prevotella were ermF-positive, although expression of e
rythromycin resistance was not consistently associated with detection of th
is gene. Antibiotic resistance phenotypes of Prevotella isolates were shown
to be related to specific chromosomal restriction patterns by hybridizatio
n studies: tetracycline resistance and tetracycline/erythromycin resistance
are conferred by Bacteroides tetracycline-resistant ERL elements, whereas
the tetracycline/peniciilin resistance phenotype could be due to spread of
elements identified in Prevotella only. Tetracycline/erythromycin-resistant
and tetvacycline/erythromycin/penicillin-resistant P. melaninogenica isola
tes were found in this study. It appeared that the presence of tetQ and erm
F in Bacteroides and Prevotella contributed to the persistence of antibioti
c resistance isolates within the host and to potential spread to other orga
nisms through conjugal elements.