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Journal of Clinical Microbiology, April 2006, p. 1590-1591, Vol. 44, No. 4
0095-1137/06/$08.00+0 doi:10.1128/JCM.44.4.1590-1591.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Fluoroquinolone Resistance in Ureaplasma parvum in the United States
Lynn Duffy,1
John Glass,2
Geraldine Hall,3
Robin Avery,3
Raymond Rackley,3
Scott Peterson,4 and
Ken Waites1*
Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama,1
J. Craig Venter Institute,2
The Institute for Genomic Research, Rockville, Maryland,4
Cleveland Clinic Foundation, Cleveland, Ohio3
Received 20 December 2005/
Returned for modification 26 January 2006/
Accepted 2 February 2006

ABSTRACT
We report the first case of naturally occurring fluoroquinolone
resistance in
Ureaplasma spp. from the United States. Resistance
in this case probably developed as a result of mutations in
the
gyrA and
parC genes of the DNA gyrase/topoisomerase IV complex
that occurred in the presence of antimicrobial selective pressure.

INTRODUCTION
A 28-year-old woman receiving care through the Cleveland Clinic
with a history of chronic bladder infections and severe bladder
thickening had been treated with prolonged courses of tetracycline,
azithromycin, and ofloxacin. She had numerous vaginal cultures
that were positive for
Ureaplasma spp. as well as urine cultures
that were positive for
Klebsiella pneumoniae. The vaginal ureaplasma
isolate, designated 48105, was submitted for antimicrobial susceptibility
testing and speciation in January 2002. MICs (Table
1) determined
by broth microdilution (
13) showed elevated values for all fluoroquinolones,
but results were no different than what would be expected for
erythromycin and doxycycline (
14). MICs were confirmed by repeat
testing. After susceptibility test results were reported, she
was treated with doxycycline. However, therapeutic response
continued to be poor, and she eventually underwent cystectomy
with urinary diversion and placement of a ureteral stent. Despite
surgical intervention, she was subsequently admitted to other
hospitals over several months for uroseptic episodes. The ureaplasma
isolate was identified to the species level as
U. parvum by
PCR using species-specific probes for conserved regions of
Ureaplasma 16S rRNA (
9).
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TABLE 1. MICs for fluoroquinolone-resistant Ureaplasma parvum 48105 compared to those of Ureaplasma species in generala
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Bacterial resistance to fluoroquinolones has been attributed
to substitution mutations, principally in the
gyrA and
parC genes and, to a lesser extent, in the
gyrB and
parE genes of
the DNA gyrase/topoisomerase IV complex (
6). The mechanism of
fluoroquinolone resistance in
U. parvum 48105 was investigated
by amplification of these genes by PCR and sequencing of purified
PCR products using corresponding sequences of the published
ureaplasma genome as a basis for comparative analysis and identification
of base substitutions (
8).
U. parvum cells were grown in 200
ml of 10B medium (
13), and genomic DNA was extracted from pelleted
cells using a QIAGEN DNeasy Tissue kit (QIAGEN, Inc., Valencia,
CA) according to the manufacturer's instructions. PCR primers
flanking
gyrA (UU082),
gyrB (UU081),
parC (UU467), and
parE (UU466) genes were designed based on the
U. parvum serovar 3
genome sequence (
8), and each gene was then amplified. DNA sequences
of the PCR amplicons were determined using an Applied Biosystems
3730XL sequencer (Foster City, CA) and were primed by the PCR
primers as well as oligonucleotides that annealed in the central
regions of the genes. Both strands of each amplicon were sequenced.
Six mutations were identified in the U. parvum 48105 parC gene, five mutations in parE, and one mutation in gyrA that resulted in amino acid substitutions (Table 2). There were only three silent mutations observed in gyrB. The gyrA mutation that resulted in the substitution of glutamine for lysine at amino acid 103 in U. parvum 48105 may be near enough to the tyrosine active site of the protein at amino acid 122 to contribute to the resistance observed.
Twenty-six clinical isolates of fluoroquinolone-resistant
Ureaplasma spp. have been described thus far from China (
15) and France
(
1,
2). Although a variety of mutations were detected, the most
frequently observed genetic alterations were replacement of
serine at amino acid 83 of UU467 (
parC) with leucine and replacement
of the asparagine at amino acid 112 of UU082 (
gyrA) with glutamic
acid. These mutations occurred singly in 13 isolates and in
tandem in 12. Twelve of the 13 fluoroquinolone-resistant isolates
had mutations in both genes. One of the
parC mutations observed
in
U. parvum 48105 had the same serine-to-leucine alteration
at
parC amino acid 83 that has been previously reported for
several of the aforementioned French and Chinese fluoroquinolone-resistant
Ureaplasma isolates. Contributions of the other five
parC amino
acid substitutions and all five amino acid substitutions in
the
parE gene to fluoroquinolone resistance observed in
U. parvum 48105 appear unlikely, since they are located outside the quinolone
resistance-determining region.
K. pneumoniae was isolated from urine of this patient on multiple occasions in addition to the vaginal isolations of Ureaplasma spp. during the same time period. However, there were other episodes when she was extremely symptomatic in which no pathogenic bacteria other than vaginal U. parvum were detected. Thus, it was the impression of her clinicians that U. parvum was the major cause of her urological problems. Irrespective of the importance of U. parvum from a clinical standpoint in this case, this represents the first reported isolation of a ureaplasma from a human in North America with naturally occurring resistance to fluoroquinolones.
Ureaplasma spp. are commonly found in the lower urogenital tract of healthy women, but they have sometimes been implicated as causes of acute and chronic infections of the urinary tract (7, 10-12). Eradication of ureaplasmas from the female vagina has proven difficult, sometimes necessitating prolonged courses of antimicrobial therapy (3). Fluoroquinolones are attractive choices for treating urinary tract infections. They are bactericidal, and thus far there have been very few documented reports of naturally occurring resistance in human ureaplasmas. It is likely that fluoroquinolone resistance in Ureaplasma spp. may occur to some degree in view of the widespread use of these drugs for treatment of respiratory and urogenital infections. Data on antimicrobial resistance in ureaplasmas are very limited, because Ureaplasma spp. cultures are rarely obtained for clinical purposes and in vitro susceptibilities are almost never performed. We recently reported that 45% of Ureaplasma spp. were tetracycline resistant and contained tet(M), indicating that resistance to other drug classes is also increasing (14). Documented resistance of Ureaplasma spp. to fluoroquinolones in the United States underscores the importance of performing susceptibility tests on these organisms in the event of fluoroquinolone treatment failure for a condition known to be associated with them, as well as in any circumstance where eradication may be difficult and/or require prolonged administration of drugs, such as in immunocompromised hosts. Evidence that the mutations described above are responsible for the fluoroquinolone resistance in U. parvum 48105 is circumstantial. In recent years, site-directed mutagenesis protocols have been reported for Mycoplasma genitalium, a close phylogenetic relative of the ureaplasmas (4, 5). Similar methods might be effective for performing allelic replacement experiments on fluoroquinolone-resistant ureaplasmas to confirm whether the observed mutations fully account for the phenotype.

ACKNOWLEDGMENTS
The technical assistance of Donna Crabb and Padma Patel in performance
of susceptibility tests and species identification of
Ureaplasma parvum is gratefully acknowledged.

FOOTNOTES
* Corresponding author. Mailing address: Department of Pathology, WP 230, 619 19th St. South, University of Alabama at Birmingham, Birmingham, AL 35226. Phone: (205) 934-4960. Fax: (205) 975-4468. E-mail:
waites{at}path.uab.edu.


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Journal of Clinical Microbiology, April 2006, p. 1590-1591, Vol. 44, No. 4
0095-1137/06/$08.00+0 doi:10.1128/JCM.44.4.1590-1591.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
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