Lynn B Duffy

University of Alabama at Birmingham, Birmingham, Alabama, United States

Are you Lynn B Duffy?

Claim your profile

Publications (75)346.93 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Susceptibilities were determined for AZD0914, a spiropyrimidinetrione DNA gyrase inhibitor, azithromycin, doxycycline, and levofloxacin against Mycoplasma and Ureaplasma species. AZD0914 activity was comparable to levofloxacin and doxycycline against M. genitalium and M. pneumoniae. AZD0914 MIC90 against M. hominis was 8-fold greater than levofloxacin. AZD0914 MIC90 against Ureaplasma species was 4-fold less than azithromycin and 8-fold less than levofloxacin and doxycycline. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    No preview · Article · Mar 2015 · Antimicrobial Agents and Chemotherapy
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Modern warfare has caused a large number of severe extremity injuries, many of which become infected. In more recent conflicts, a pattern of co-infection with Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus has emerged. We attempted to recreate this pattern in an animal model to evaluate the role of vascularity in contaminated open fractures. Historically, it has been observed that infected bones frequently appear hypovascular, but vascularity in association with bone infection has not been examined in animal models. Adult rats underwent femur fracture and muscle crush injury followed by stabilization and bacterial contamination with A. baumannii complex and methicillin-resistant Staphylococcus aureus. Vascularity and perfusion were assessed by microCT angiography and SPECT scanning, respectively, at 1, 2 and 4 weeks after injury. Quantitative bacterial cultures were also obtained. Multi-bacterial infections were successfully created, with methicillin-resistant S. aureus predominating. There was overall increase in blood flow to injured limbs that was markedly greater in bacteria-inoculated limbs. Vessel volume was greater in the infected group. Quadriceps atrophy was seen in both groups, but was greater in the infected group. In this animal model, infected open fractures had greater perfusion and vascularity than non-infected limbs.
    Full-text · Article · Jan 2015
  • Amy E Ratliff · Lynn B Duffy · Ken B Waites
    [Show abstract] [Hide abstract]
    ABSTRACT: A loop-mediated isothermal amplification (LAMP) system, the illumigene Mycoplasma DNA amplification assay (Meridian Bioscience, Inc., Cincinnati, OH) was evaluated to determine its analytical sensitivity, specificity, and clinical application in comparison to historic culture in a collection of archived respiratory specimens. The illumigene limit of detection was ≤88 CFU/reaction for 10 Mycoplasma pneumoniae reference strains. This assay correctly identified 36 M. pneumoniae reference strains and clinical isolates from various geographic origins, including both of the main subtypes. No cross-reactions were detected with other mycoplasmas, ureaplasmas, other bacterial species, viruses, yeasts, or human DNA. Among 214 respiratory specimens previously cultured for M. pneumoniae, when real-time PCR with bidirectional sequencing of the PCR products was used to resolve discrepancies, the sensitivity was 22 of 22 (100%) and the specificity was 190 of 192 (99%). This commercial LAMP assay is a useful rapid method for detecting M. pneumoniae in clinical specimens. Additional prospective clinical trials with direct comparison to culture and PCR are warranted.
    No preview · Article · Jan 2014 · Journal of clinical microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background. Our goals were to describe azithromycin (AZI) pharmacokinetics in maternal plasma (MP), fetal plasma (FP), and amniotic fluid (AF) following intra-amniotic infection (IAI) with Ureaplasma in pregnant rhesus monkeys and to explore concentration-response relationships.Methods. Following intra-amniotic inoculation of Ureaplasma parvum, rhesus monkeys received AZI (12.5 mg/kg every 12 hours intravenously for 10 days; n = 10). Intensive pharmacokinetic sampling of MP, FP, and AF was scheduled following the first (ie, single) dose and the last (ie, multiple) dose. Noncompartmental and pharmacokinetic modeling methods were used.Results. The AF area under the concentration-time curve at 12 hours was 0.22 g×h/mL following a single dose and 6.3 g×h/mL at day 10. MP and AF accumulation indices were 8.4 and 19, respectively. AZI AF half-life following the single dose and multiple dose were 156 and 129 hours, respectively. The median MP:FP ratio in concomitantly drawn samples was 3.2 (range, 1.3-9.6; n = 9). Eradication of U. parvum occurred at 6.6 days, with a 95% effective concentration (EC95) of 39 ng/mL for the maximum AZI AF concentration.Conclusions. Our study demonstrates that a maternal multiple-dose AZI regimen is effective in eradicating U. parvum IAI by virtue of intra-amniotic accumulation and suggests that antenatal therapy has the potential to mitigate complications associated with U. parvum infection in pregnancy, such as preterm labor and fetal sequelae. © 2013 The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: [email protected] /* */
    Preview · Article · Oct 2013 · The Journal of Infectious Diseases
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: We assessed the efficacy of a maternal multidose azithromycin (AZI) regimen, with and without antiinflammatory agents to delay preterm birth and to mitigate fetal lung injury associated with Ureaplasma parvum intraamniotic infection. Study design: Long-term catheterized rhesus monkeys (n = 16) received intraamniotic inoculation of U parvum (10(7) colony-forming U/mL, serovar 1). After contraction onset, rhesus monkeys received no treatment (n = 6); AZI (12.5 mg/kg, every 12 h, intravenous for 10 days; n = 5); or AZI plus dexamethasone and indomethacin (n = 5). Outcomes included amniotic fluid proinflammatory mediators, U parvum cultures and polymerase chain reaction, AZI pharmacokinetics, and the extent of fetal lung inflammation. Results: Maternal AZI therapy eradicated U parvum intraamniotic infection from the amniotic fluid within 4 days. Placenta and fetal tissues were 90% culture negative at delivery. AZI therapy significantly delayed preterm delivery and prevented advanced fetal lung injury, although residual acute chorioamnionitis persisted. Conclusion: Specific maternal antibiotic therapy can eradicate U parvum from the amniotic fluid and key fetal organs, with subsequent prolongation of pregnancy, which provides a therapeutic window of opportunity to effectively reduce the severity of fetal lung injury.
    No preview · Article · Oct 2012 · American journal of obstetrics and gynecology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An international multilaboratory collaborative study was conducted to develop standard media and consensus methods for the performance and quality control of antimicrobial susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum using broth microdilution and agar dilution techniques. A reference strain from the American Type Culture Collection was designated for each species, which was to be used for quality control purposes. Repeat testing of replicate samples of each reference strain by participating laboratories utilizing both methods and different lots of media enabled a 3- to 4-dilution MIC range to be established for drugs in several different classes, including tetracyclines, macrolides, ketolides, lincosamides, and fluoroquinolones. This represents the first multilaboratory collaboration to standardize susceptibility testing methods and to designate quality control parameters to ensure accurate and reliable assay results for mycoplasmas and ureaplasmas that infect humans.
    Full-text · Article · Aug 2012 · Journal of clinical microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Ureaplasma urealyticum (UUR) and Ureaplasma parvum (UPA) are sexually transmitted bacteria among humans implicated in a variety of disease states including but not limited to: nongonococcal urethritis, infertility, adverse pregnancy outcomes, chorioamnionitis, and bronchopulmonary dysplasia in neonates. There are 10 distinct serotypes of UUR and 4 of UPA. Efforts to determine whether difference in pathogenic potential exists at the ureaplasma serovar level have been hampered by limitations of antibody-based typing methods, multiple cross-reactions and poor discriminating capacity in clinical samples containing two or more serovars. Results We determined the genome sequences of the American Type Culture Collection (ATCC) type strains of all UUR and UPA serovars as well as four clinical isolates of UUR for which we were not able to determine serovar designation. UPA serovars had 0.75−0.78 Mbp genomes and UUR serovars were 0.84−0.95 Mbp. The original classification of ureaplasma isolates into distinct serovars was largely based on differences in the major ureaplasma surface antigen called the multiple banded antigen (MBA) and reactions of human and animal sera to the organisms. Whole genome analysis of the 14 serovars and the 4 clinical isolates showed the mba gene was part of a large superfamily, which is a phase variable gene system, and that some serovars have identical sets of mba genes. Most of the differences among serovars are hypothetical genes, and in general the two species and 14 serovars are extremely similar at the genome level. Conclusions Comparative genome analysis suggests UUR is more capable of acquiring genes horizontally, which may contribute to its greater virulence for some conditions. The overwhelming evidence of extensive horizontal gene transfer among these organisms from our previous studies combined with our comparative analysis indicates that ureaplasmas exist as quasi-species rather than as stable serovars in their native environment. Therefore, differential pathogenicity and clinical outcome of a ureaplasmal infection is most likely not on the serovar level, but rather may be due to the presence or absence of potential pathogenicity factors in an individual ureaplasma clinical isolate and/or patient to patient differences in terms of autoimmunity and microbiome.
    Full-text · Article · May 2012 · BMC Microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We sequenced the full lengths of the gyrA, gyrB, parC, and parE genes in 13 fluoroquinolone-resistant Ureaplasma isolates (levofloxacin MICs, 4 to 32 μg/ml) and 10 susceptible isolates (MICs ≤ 2 μg/ml). Mutations were detected in all resistant isolates but in none of the susceptible isolates. The most prevalent mutation was the S83L substitution in the ParC protein. No plasmid-mediated fluoroquinolone resistance genes were detected.
    Full-text · Article · Feb 2012 · Antimicrobial Agents and Chemotherapy
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Genetic relationships within ureaplasma serovars were investigated by pulsed-field gel electrophoresis (PFGE). One hundred thirteen Ureaplasma parvum isolates and 78 Ureaplasma urealyticum isolates were different from their ATCC serovar type strains and different within the same serovars. The organisms were geographically widespread. No unique patterns were associated with invasive disease.
    Full-text · Article · Jul 2011 · Journal of clinical microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ureaplasma parvum and Ureaplasma urealyticum are sexually transmitted, opportunistic pathogens of the human urogenital tract. There are 14 known serovars distributed between the two species. For decades, it has been postulated based upon limited data that virulence is related to serotype specificity. The results were often inconclusive due to the small sample size and extensive cross-reactivity between certain serovars. We developed real-time quantitative PCRs that allow reliable differentiation of the two species and type strains of each of the 14 serovars. To investigate species and serovar distributions, we typed 1,061 clinical isolates of human ureaplasmas from diverse patient populations. There was only a tenuous association between individual Ureaplasma serovars and certain patient populations. This may in part be explained by the fact that almost 40% of the isolates were genetic mosaics, apparently arising from the recombination of multiple serovars. This explains the extensive cross-reactivity based upon serotyping and the lack of consistent association of given serotypes with disease.
    Full-text · Article · Jun 2011 · Journal of clinical microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Genetic mechanisms of macrolide resistance were investigated in six isolates of Ureaplasma spp. with erythromycin minimum inhibitory concentrations (MICs)≥ 8 μg/mL that were derived from 370 cultures obtained over a several year period. Point mutations in domain V of 23S rRNA and/or mutations in ribosomal protein L4 genes are likely to be responsible for this drug resistance. Overall, macrolide resistance was uncommon, in contrast to tetracycline resistance that was documented in 121 unique isolates (33%).
    No preview · Article · Feb 2011 · International journal of antimicrobial agents
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mycoplasma pneumoniae (Mp), a common cause of pneumonia, is associated with asthma; however, the mechanisms underlying this association remain unclear. We investigated the cellular immune response to Mp in mice. Intranasal inoculation with Mp elicited infiltration of the lungs with neutrophils, monocytes and macrophages. Systemic depletion of macrophages, but not neutrophils, resulted in impaired clearance of Mp from the lungs. Accumulation and activation of macrophages were decreased in the lungs of MyD88(-/-) mice and clearance of Mp was impaired, indicating that MyD88 is a key signaling protein in the anti-Mp response. MyD88-dependent signaling was also required for the Mp-induced activation of NFκB, which was essential for macrophages to eliminate the microbe in vitro. Thus, MyD88-NFκB signaling in macrophages is essential for clearance of Mp from the lungs.
    Full-text · Article · Dec 2010 · PLoS ONE
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ureaplasma respiratory tract colonization is associated with bronchopulmonary dysplasia (BPD) in preterm infants. Whether the 4 Ureaplasma parvum and 10 Ureaplasma urealyticum serovars differ in virulence is unknown. This study was conducted to determine the distribution of Ureaplasma serovars in respiratory secretions of a prospective cohort of preterm infants and to assess whether any of the serovars are associated with BPD. Serial endotracheal and/or nasopharyngeal aspirates were obtained for Ureaplasma culture and PCR from 136 infants of gestational age <33 weeks. All positive samples were speciated and serovars were determined by real-time PCR. A total of 51 (37.5%) infants were Ureaplasma-positive one or more times during the first month of life. Respiratory colonization was inversely related to gestational age. Sixty-five percent of infants <26 weeks compared with 31% infants ≥ 26 weeks were culture or PCR positive. U. parvum was more common (N = 32, 63%) than U. urealyticum (N = 17, 33%); both species were present in 2 samples. Serovars 3 and 6 alone and in combination accounted for 96% U. parvum isolates. U. urealyticum isolates were commonly a mixture of multiple serovars, with serovar 11 alone or combined with other serovars (10/17, 59%) being the most common serovar. No individual species or serovars or serovar mixtures were associated with moderate-to-severe BPD. U. parvum serovars 3 and 6 and U. urealyticum serovar 11 were the most common serovars detected in respiratory samples from a prospective cohort of preterm infants.
    Preview · Article · Nov 2010 · The Pediatric Infectious Disease Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ureaplasma spp. respiratory tract colonization is a significant risk factor for bronchopulmonary dysplasia (BPD), a chronic lung disorder in preterm infants. As an initial step preparatory to future clinical trials to evaluate the clinical efficacy of azithromycin to prevent BPD, the authors characterized the pharmacokinetics, safety, and biological effects of a single intravenous dose of azithromycin (10 mg/kg) in preterm neonates (n = 12) 24 to 28 weeks gestation at risk for Ureaplasma infection and BPD. A 2-compartment structural model with the clearance and volume of peripheral compartment (V2) allometrically scaled on body weight (WT) best described the pharmacokinetics of azithromycin in preterm neonates. The estimated parameters were clearance [0.18 L/h × WT(kg)(0.75)], intercompartmental clearance [1.0 L/h], volume of distribution of central compartment [0.93 L], and V2 [14.2 L × WT(kg)]. There were no serious adverse events attributed to azithromycin. A single dose of azithromycin did not suppress inflammatory cytokines or myeloperoxidase activity in tracheal aspirates. These results demonstrated the safety of azithromycin and developed a pharmacokinetic model that is useful for future simulation-based clinical trials for eradicating Ureaplasma and preventing BPD in preterm neonates.
    No preview · Article · Nov 2010 · The Journal of Clinical Pharmacology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Open fractures with bone loss are common, disabling injuries. Biodegradable, load-bearing scaffolds able to carry high concentrations of local antibiotics are an emerging technology to address these injuries. This study investigates the use of such scaffolds with gentamicin (along with bone morphogenetic protein) in an infected rat open fracture model to decrease osteomyelitis and promote fracture healing. A contaminated open fracture was created in 32 Brown Norway rats. A comminuted femoral fracture was created, followed by crushing, and the 5-mm bone defect was inoculated with Staphylococcus aureus (10 colony-forming units/mL) and Escherichia coli (10 colony-forming units/mL). The scaffold was stabilized in the defect with an intramedullary Kirschner wire. Gentamicin was loaded onto the scaffolds at two doses, either 10 mg (n = 12) or 20 mg (n = 10). Controls (n = 10) received no antibiotics. All three groups had 10 microg bone morphogenetic protein loaded on the scaffold. Serial radiographs were obtained. Microbiologic analysis, microcomputed tomography, and histology were performed. There was a statistically significant difference in the radiographic evidence of osteomyelitis (P = 0.004) and callus formation (P = 0.021) between the treated and control groups. Bone culture analysis results were not significant for S. aureus (P = 0.29) or E. coli (P = 0.25). There was no difference in the mean scaffold volume or density of the three treatment groups. Our results suggest that gentamicin applied to a biodegradable scaffold is effective at decreasing radiographically defined osteomyelitis in an infected open fracture.
    Full-text · Article · Sep 2010 · Journal of orthopaedic trauma
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We designed primers and probes for the detection and discrimination of Ureaplasma parvum and U. urealyticum and their 14 serovars by real-time PCR. The analytical sensitivity and specificity of the multiplex species-specific PCR were determined by testing corresponding American Type Culture Collection (ATCC) type strains, 47 other microbial species, and human genomic DNA. The limits of the multiplex PCR were 2.8 × 10−2 CFU/μl PCR mixture for detecting U. parvum and 4.1 × 10−2 CFU/μl PCR mixture for detecting U. urealyticum. Clinical specificity and sensitivity were proven by comparison with culture and traditional PCR. For the detection of any Ureaplasma species, the clinical sensitivity and specificity of real-time PCR were 96.9% and 79.0%, respectively, using culture as a reference. Multiplex real-time PCR was also more sensitive than traditional PCR in discriminating the two Ureaplasma species in culture-positive subcultures. Each of the 14 monoplex serovar-specific PCR assays was specific for the corresponding ATCC type strain serovar. This new species identification PCR is specific and sensitive in the detection of Ureaplasma species in clinical specimens, and the serovar-specific PCR assays are the first set of complete genotypic assays to differentiate all 14 known Ureaplasma serovars. These assays provide quick and reliable means for investigating the epidemiology and pathogenicity of ureaplasmas at the serovar level.
    Full-text · Article · Aug 2010 · Journal of clinical microbiology

  • No preview · Article · Dec 2009 · American Journal of Obstetrics and Gynecology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Epidemiologic data from Asia have documented the rapid and extensive emergence of macrolide resistance in Mycoplasma pneumoniae. This drug resistance has also been documented in Europe and recently in the United States, but there is very little information currently available on its prevalence. A rapid technique to identify macrolide-resistant M. pneumoniae is needed to guide management of patients with community-acquired respiratory infections. Culture and Minimum Inhibitory Concentration testing identified macrolide-resistant M. pneumoniae infection in 2 seriously ill hospitalized children with community-acquired pneumonia. A portion of the 23S ribosomal RNA gene from 2 macrolide-resistant M. pneumoniae isolates from these children as well as 4 laboratory-induced macrolide-resistant strains was amplified by PCR, and the PCR products were sequenced to identify mutations associated with macrolide resistance. A real-time PCR assay was designed to identify 3 known mutations in the 23S rRNA gene associated with macrolide resistance and applied to the clinical specimens from which these isolates were obtained and to the bacterial isolates. : Macrolide-resistant M. pneumoniae from both children were found to carry an A2063G transition in the 23S rRNA gene previously identified in resistant isolates from China, Japan, France, and recently in an encephalitis outbreak in Rhode Island. Three laboratory-induced mutant strains had an A2064G mutation whereas the other one had an A2063G mutation. A real-time PCR assay successfully detected the macrolide-resistant M. pneumoniae directly in clinical specimens and discriminated them from wild-type isolates. Macrolide-resistant M. pneumoniae can be associated with prolonged severe respiratory infection in children. Real-time PCR offers a rapid method of diagnosing macrolide resistance in community-acquired respiratory infections due to M. pneumoniae.
    Full-text · Article · Sep 2009 · The Pediatric Infectious Disease Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: Prospective studies have suggested that some individuals have a persistent IgM response to Mycoplasma pneumoniae infection with relatively little IgG production over many months. Persistence of the organism in patients with an allergic phenotype might predispose to the development of asthma. This study was designed to analyze the prevalence of M. pneumoniae infection and the immune response to that infection among children with asthma compared with controls. A prospective study was performed in 82 children with physician-diagnosed asthma and 98 nonasthmatic controls over a 5-year period comparing them for evidence of current or prior infection by M. pneumoniae using serology (IgG and IgM), culture, and polymerase chain reaction (PCR), and in vitro cellular responses to M. pneumoniae antigen. Similar numbers of controls (9/98) and asthmatic children (6/82) were PCR(+) for M. pneumoniae at some time during the study. IgM antibody to M. pneumoniae was detected in similar numbers of controls (21/98) and asthmatic children (18/82), but positive IgG antibody titers were detected in significantly more controls (13/98) than asthmatic children (3/82; p = 0.03). Similar numbers from each group were IgM(+) on more than one annual visit (9/98 controls and 7/82 asthmatic children). Antigen-driven proliferation and interferon (IFN) gamma production by mononuclear cells from IgM(+) controls were significantly greater than that of IgM(-) controls, but there was no difference in proliferation and IFN-gamma production by cells from IgM(+) and IgM(-) asthmatic children. These results suggest that asthmatic children have deficient cellular and humoral responses to M. pneumoniae infection compared with nonasthmatic controls.
    No preview · Article · Mar 2009 · Allergy and Asthma Proceedings
  • Source
    Ken B Waites · D M Crabb · Lynn B Duffy
    [Show abstract] [Hide abstract]
    ABSTRACT: MICs were determined for an investigational ketolide, CEM-101, and azithromycin, telithromycin, doxycycline, levofloxacin, clindamycin, and linezolid against 36 Mycoplasma pneumoniae, 5 Mycoplasma genitalium, 13 Mycoplasma hominis, 15 Mycoplasma fermentans, and 20 Ureaplasma isolates. All isolates, including two macrolide-resistant M. pneumoniae isolates, were inhibited by CEM-101 at ≤0.5 μg/ml, making CEM-101 the most potent compound tested.
    Preview · Article · Mar 2009 · Antimicrobial Agents and Chemotherapy

Publication Stats

2k Citations
346.93 Total Impact Points

Institutions

  • 1988-2015
    • University of Alabama at Birmingham
      • • Department of Pathology
      • • Department of Microbiology
      • • Department of Medicine
      Birmingham, Alabama, United States
  • 2005
    • University of Michigan
      Ann Arbor, Michigan, United States
  • 2001
    • University of Texas Southwestern Medical Center
      • Department of Pediatrics
      Dallas, Texas, United States
  • 1994
    • Samford University
      Birmingham, Alabama, United States
  • 1992
    • University of Alabama
      Tuscaloosa, Alabama, United States
  • 1986
    • University of Cambridge
      • Department of Paediatrics
      Cambridge, England, United Kingdom