PubMed Health⌕ Search

Biomedical subjects

Betsy Foxman

Publications and source records attributed to Betsy Foxman.

At least 19 recordsLinked to original sources
PubMed2006

Contributions of molecular epidemiology to the understanding of infectious disease transmission, pathogenesis, and evolution.

PURPOSE: Describe the contributions of molecular genetics to our understanding of the molecular epidemiology of infectious diseases caused by bacteria. METHODS: Synthesize the literature, highlighting work on Escherichia coli and Group B streptococcus. RESULTS: 1) Commensal bacteria are genetically and phenotypically diverse. 2) Disease-causing strains of commensal bacteria often have special characteristics than allow them to be distinguished from common inhabitants. 3) Colonization by commensal bacteria is dynamic. 4) Commensal bacteria are transmitted between individuals. CONCLUSIONS: Applications of epidemiologic principles to bacterial populations gives insight into the natural history of colonization and transmission in the human host.

Bacterial Infections↗
PubMed2006

The frequency of genes encoding three putative group B streptococcal virulence factors among invasive and colonizing isolates.

BACKGROUND: Group B Streptococcus (GBS) causes severe infections in very young infants and invasive disease in pregnant women and adults with underlying medical conditions. GBS pathogenicity varies between and within serotypes, with considerable variation in genetic content between strains. Three proteins, Rib encoded by rib, and alpha and beta C proteins encoded by bca and bac, respectively, have been suggested as potential vaccine candidates for GBS. It is not known, however, whether these genes occur more frequently in invasive versus colonizing GBS strains. METHODS: We screened 162 invasive and 338 colonizing GBS strains from different collections using dot blot hybridization to assess the frequency of bca, bac and rib. All strains were defined by serotyping for capsular type, and frequency differences were tested using the Chi square test. RESULTS: Genes encoding the beta C protein (bac) and Rib (rib) occurred at similar frequencies among invasive and colonizing isolates, bac (20% vs. 23%), and rib (28% vs. 20%), while the alpha (bca) C protein was more frequently found in colonizing strains (46%) vs, invasive (29%). Invasive strains were associated with specific serotype/gene combinations. CONCLUSION: Novel virulence factors must be identified to better understand GBS disease.

Adolescent↗
PubMed2006

Frequency of antimicrobial resistance among invasive and colonizing Group B streptococcal isolates.

BACKGROUND: Group B Streptococcus (GBS) remains susceptible to penicillin, however, resistance to second-line antimicrobials, clindamycin and erythromycin, has increased since 1996. We describe the age-specific antibiotic susceptibility profile and capsular type distribution among invasive and colonizing GBS strains. METHODS: We tested 486 invasive GBS isolates from individuals of all ages collected by a Wisconsin surveillance system between 1998 and 2002 and 167 colonizing strains collected from nonpregnant college students during 2001 in Michigan. Antimicrobial susceptibility testing was performed by disk diffusion or Etest and capsular typing was performed using DNA dot blot hybridization RESULTS: 20.0% (97/486) of invasive and 40.7% (68/167) of colonizing isolates were resistant to clindamycin (P < .001) and 24.5% (119/486) of invasive and 41.9% (70/167) of colonizing isolates were resistant to erythromycin (P < .001). Similarly, 19.8% (96/486) of invasive and 38.3% (64/167) of colonizing isolates were resistant to both antimicrobial agents (P < .001). 29.4% (5/17) of invasive isolates from persons 18-29 years of age and 24.3% (17/70) of invasive isolates from persons 30-49 years of age were resistant to clindamycin. Similarly, 35.3% (6/17) of invasive isolates from persons 18-29 years of age and 31.4% (22/70) of invasive isolates from persons 30-49 years of age were resistant to erythromycin. 34.7% (26/75) of invasive isolates from persons < 1 year of age were capsular type Ia, whereas capsular type V predominated among isolates from adults. CONCLUSION: Clindamycin and erythromycin resistance rates were high among isolates colonizing nonpregnant college students and invasive GBS isolates, particularly among the colonizing isolates. Susceptibility profiles were similar by age although the proportion of clindamycin and erythromycin resistance among invasive isolates was highest among persons 18-49 years of age. Increasing antimicrobial resistance has implications for GBS disease treatment and intrapartum prophylaxis among penicillin intolerant patients.

Adolescent↗
PubMed2006

Recall of age of weaning and other breastfeeding variables.

BACKGROUND: Many studies of the impact of breastfeeding on child or maternal health have relied on data reported retrospectively. The goal of this study was to assess recall accuracy among breastfeeding mothers of retrospectively collected data on age of weaning, reasons for cessation, breast pain, lactation mastitis, and pumping. METHODS: Women in Michigan and Nebraska, U.S.A. were interviewed by telephone every 3 weeks during the first 3 months after the birth of their child, and mailed a questionnaire at 6 months. A subset was interviewed again by telephone approximately 1-3.5 years after the birth. The results for the three recall periods, collected 1994-1998, were compared using correlation, linear and Cox regression analysis, and sensitivity and specificity estimates. RESULTS: The 184 participants were aged 18-42, mostly white (95%) and 63% had an older child. The age of weaning tended to be overestimated in interviews 1-3.5 years after birth compared to those within 3 weeks of the event, by approximately one month for 1-3.5 year recall and two weeks for 6-month recall (p < 0.001 in both cases). Recall accuracy of reasons for weaning varied greatly by reason, with mastitis and return to work having the most recall validity. The sensitivity of 1-3.5 year recall of mastitis was 80%, but was only 54% for nipple cracks or sores. CONCLUSION: Breastfeeding duration among short-term breastfeeders tended to be somewhat overestimated when measured at 1-3.5 years post-partum. Reporting of other breastfeeding characteristics had variable reliability. Studies employing retrospective breastfeeding data should consider the possibility of such errors.

Journal Article↗
PubMed2006

The role of horizontal gene transfer in the spread of trimethoprim-sulfamethoxazole resistance among uropathogenic Escherichia coli in Europe and Canada.

OBJECTIVES: To describe the distribution of trimethoprim-sulfamethoxazole resistance genes and the role of horizontal gene transfer and clonal expansion in recent increases of antibiotic resistance rates among uropathogenic Escherichia coli in Europe and Canada. METHODS: We identified antibiotic resistance alleles sul1, sul2, sul3 and dfr along with type 1 and type 2 integrons among 350 uropathogenic E. coli isolates from a cross-sectional study of acute, uncomplicated, community-acquired urinary tract infections in 16 western European countries and Canada (ECOSENS). RESULTS: Trimethoprim resistance gene distributions showed no regional dependency (P = 0.84). The most common trimethoprim resistance gene was dfrA1, which occurred in 37.9% of dfr containing isolates. Similarly, the sulfamethoxazole resistance gene distributions did not vary significantly by region (P = 0.20). sul2, the most common sulfamethoxazole resistance gene, was found in 77.9% of sulfamethoxazole-resistant isolates. The distribution of type 1 and type 2 integrons varied slightly by region (P = 0.04) with type 1 integrons being the more common (85.9%). We observed 34 combinations of the sul genes, dfr genes and integron types; the most common combinations were broadly disseminated across every region examined. CONCLUSIONS: Horizontal gene transfer plays a larger role than clonal expansion in the increase of trimethoprim-sulfamethoxazole resistance levels in Europe and Canada.

Anti-Bacterial Agents↗
PubMed2006

Incidence and duration of group B Streptococcus by serotype among male and female college students living in a single dormitory.

Group B Streptococcus causes a variety of morbid and sometimes fatal conditions affecting individuals of all age groups. There are nine known serotypes of this Gram-positive coccus but few estimates of the incidence and duration of its colonization and none by serotype in the literature. In 2001, the authors conducted a prospective cohort study among 257 men and women living in a single dormitory in Ann Arbor, Michigan. The 3-week incidence with any serotype was 11.3% (+/-3.9%) among women and 8.8% (+/-3.0%) among men; 3-week incidence rates were highest for serotype V (4.7% for women and 3.5% for men) and type Ia (2.3% for women and 2.4% for men), with no significant differences by gender. The estimated average duration of any group B Streptococcus colonization was longer for women (13.7 weeks) than men (8.5 weeks); serotype Ia was carried an average of 6.5 weeks longer in women, and serotype III was carried 4.9 weeks longer. Colonization with more than one serotype occurred significantly less than would be expected by chance (p <<< 0.001). Based on the overall incidence, transmission occurred between roommate pairs at the rate expected. Group B Streptococcus colonization is frequent and dynamic, but it is not transmitted by casual contact.

Adolescent↗
PubMed2006

Predictors for Haemophilus influenzae colonization, antibiotic resistance and for sharing an identical isolate among children attending 16 licensed day-care centers in Michigan.

BACKGROUND: Nontypable Haemophilus influenzae is an important cause of otitis media in children. Children attending day-care centers are at an increased risk for nontypable H. influenzae colonization and otitis media. We describe the prevalence of nontypable H. influenzae colonization, antibiotic resistance and predictors for colonization and sharing an identical isolate with at least 1 other child in the same day-care centers among children attending 16 day-care centers. METHODS: Throat swabs of 198 children < 3 years old attending 16 day-care centers were cultured for H. influenzae. Day-care center directors and parents completed risk factors questionnaires. Nontypable H. influenzae isolates were screened for antibiotic resistance and genotyped. Statistics were performed using SAS software (SAS Institute, Inc., Cary, NC). RESULTS: We isolated 179 unique nontypable H. influenzae strains from 127 participants. Colonization ranged from 0% to 95% among day-care centers. As individual factors, exposure to tobacco smoke was associated with colonization (P = 0.05), and racial self-identifications as "other" (nonwhite, nonblack) was protective (P = 0.035), whereas as "black" was protective for sharing (P = 0.03). Pacifier use was associated with sharing (P = 0.04), but not with colonization. As day-care centers factors, rates of colonization and sharing were higher in day-care centers with > or = 5 classrooms (P < 0.01 and P = 0.03), with such suboptimal hygiene habits as minimal hand washing by staff after eating (P < 0.002 and P < 0.01) or by children after wiping their own nose (P = 0.01 and P = 0.003). Of colonized children, 41% presented a beta-lactamase-producing strain. Colonized children were more likely to carry resistant strains if they were taking an antibiotic (P = 0.02). CONCLUSION: Although day-care center colonization varied, the overall colonization rate was high. Colonization with nontypable H. influenzae, with beta-lactamase-producing strain and sharing were, mostly, associated with modifiable risk factors.

Carrier State↗
PubMed2006

Common use in the general population of sexual enrichment AIDS and drugs to enhance sexual experience.

BACKGROUND: We describe the prevalence of ever and current use of sexual enrichment aids and of using drugs to enhance the sexual experience, and correlates of that usage. STUDY POPULATION: Participants in a random-digit dial survey conducted in the Seattle area between 2003 and 2004 among residents age 18 to 39 years of age with fluency in the English language. RESULTS: Use of sexual enrichment aids and drugs to enhance sexual experience during a typical 4-week period were reported by 27% and 13%, respectively, of participants. Among those reporting using a drug to enhance their sexual experience, the most commonly used drugs were alcohol (83.7%), marijuana (34.7%), ecstasy or "sextasy" (ecstasy combined with sildenafil) (8.2%), and sildenafil (7.5%). Persons reporting use of sexual enrichment aids and drugs to enhance sexual experience were more likely to engage in sexual behaviors associated with a higher risk of acquiring and transmitting a sexually transmitted infection (STI),such as having nonmonogamous partnerships and multiple partners in the previous 12 months and sexual repertoire. CONCLUSION: Whether use of sexual enrichment aids and drugs to enhance sexual experience is causally associated with STI risk or merely an additional marker of high-risk behavior or sensation seeking cannot be discerned from a single cross-sectional survey. However, these behaviors occurred frequently, and usage was common across all age, gender, ethnic, sexual, and income groups. Further studies in STI and other populations are required.

Adolescent↗
PubMed2006

Measures of sexual partnerships: lengths, gaps, overlaps, and sexually transmitted infection.

GOAL: The length of time between partnerships ("gap") is an important determinant of the overall transmission system of sexually transmitted infections. We describe the distributions of gaps, lengths, and overlaps among participants in a random-digit dialing survey conducted among 1194 Seattle residents during 2003-2004. METHODS: Survey participants were restricted to those 18 to 39 years of age with fluency in the English language. We limited our analysis to the 1051 (88%) participants who reported ever engaging in vaginal, oral, or anal intercourse and reported information on gaps, lengths, and overlaps. RESULTS: Most (59%) observed gaps between partnerships were of length<or=6 months; therefore, the majority of 18- to 39-year-olds seeking new partners find a new partner well within the infectious period of chlamydia infection, gonorrhea, and syphilis (if no treatment is received) and herpes simplex virus, human papilloma virus, and human immunodeficiency virus infections. This was generally true independent of gender, race, income, or education. Gap length, however, correlated with age. CONCLUSIONS: The observed shorter gap lengths among younger individuals reinforce the need to focus interventions on adolescents and young adults, particularly those with the potential to mix with infected individuals.

Adolescent↗
PubMed2006

Molecular epidemiologic identification of Escherichia coli genes that are potentially involved in movement of the organism from the intestinal tract to the vagina and bladder.

A first step in urinary tract infection (UTI) pathogenesis in the otherwise healthy host is the movement of uropathogenic Escherichia coli from the intestinal tract to the urinary tract. We conducted a genomic subtraction to isolate genetic regions associated with this movement. A representative UTI isolate present in the rectum, vagina, and bladder of a woman with UTI was chosen as the tester; the driver was a phylogenetically distant rectal isolate (based on pulsed-field gel electrophoresis analysis) with a profile of uropathogenic virulence genes similar to that of the tester. Tester-specific regions identified by the subtraction were screened, using DNA dot blot hybridization, against a collection of 88 uropathogens isolated from the rectum, urine, and/or vagina of women with UTIs and 54 E. coli isolates from the same women that were found only in the rectum. Twelve genetic regions occurred more often in multisite isolates than in rectal site-only isolates. Eleven of these 12 genetic regions are homologous to regions in the sequenced uropathogenic E. coli CFT073 strain.

Cluster Analysis↗
PubMed2005

Choosing an appropriate bacterial typing technique for epidemiologic studies.

A wide variety of bacterial typing systems are currently in use that vary greatly with respect to the effort required, cost, reliability and ability to discriminate between bacterial strains. No one technique is optimal for all forms of investigation. We discuss the desired level of discrimination and need for a biologic basis for grouping strains of apparently different types when using bacterial typing techniques for different epidemiologic applications: 1) confirming epidemiologic linkage in outbreak investigations, 2) generating hypotheses about epidemiologic relationships between bacterial strains in the absence of epidemiologic information, and 3) describing the distributions of bacterial types and identifying determinants of those distributions. Inferences made from molecular epidemiologic studies of bacteria depend upon both the typing technique selected and the study design used; thus, choice of typing technique is pivotal for increasing our understanding of the pathogenesis and transmission, and eventual disease prevention.

Journal Article↗
PubMed2005

Simultaneous detection of isoniazid, rifampin, and ethambutol resistance of Mycobacterium tuberculosis by a single multiplex allele-specific polymerase chain reaction (PCR) assay.

Prompt detection of drug resistance of Mycobacterium tuberculosis is essential for effective control of tuberculosis (TB). We developed a multiplex allele-specific polymerase chain reaction (MAS-PCR) that detects the most commonly observed isoniazid (INH), rifampin (RIF), and ethambutol resistance-associated mutations in a single assay. The usefulness of the newly developed method was evaluated with 174 clinical isolates of M. tuberculosis obtained from Turkey. Distinct PCR banding patterns were observed for different mutation profiles and the correlation between MAS-PCR results and DNA sequencing findings was 99.4%. With culture-based phenotypic drug susceptibility testing as a reference standard, the sensitivity and specificity of the newly developed MAS-PCR assay for drug resistance-related genetic mutation detection were determined to be 81.1% and 97.5% for INH, 93.0% and 98.9 % for RIF, and 54.5% and 68.0 % for ethambutol. MAS-PCR provides a rapid, potentially more cost-effective, method of detecting multidrug-resistant TB.

Alleles↗
PubMed2005

Escherichia coli mediated urinary tract infections: are there distinct uropathogenic E. coli (UPEC) pathotypes?

A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease.

Animals↗
PubMed2005

Clinical relevance of Mycobacterium tuberculosis plcD gene mutations.

To identify Mycobacterium tuberculosis virulence factors, we integrated comparative genomics and epidemiologic data analysis to investigate the relationship between certain genomic insertions and deletions in the phospholipase-C gene D (plcD) with the clinical presentation of tuberculosis (TB). Four hundred ninety-six well-characterized M. tuberculosis clinical isolates were studied. Approximately 30% (147) of the isolates had an interruption of the plcD gene. Patients infected with the plcD mutant were twice as likely to have extrathoracic disease as those infected by a strain without an interruption (adjusted odds ratio, 2.19; 95% confidence interval, 1.27, 3.76). When we limited the analysis to the 275 isolates with distinct DNA fingerprint patterns, we observed the same association (adjusted odds ratio, 2.74; 95% confidence interval, 1.35, 5.56). Furthermore, the magnitude of the association appeared to differ with the type of extrathoracic TB. Our findings suggest that the plcD gene of M. tuberculosis is potentially involved in the pathogenesis of TB, and the clinical presentation of the disease may be influenced by the genetic variability of the plcD region.

Adult↗
PubMed2005

Clonal groups and the spread of resistance to trimethoprim-sulfamethoxazole in uropathogenic Escherichia coli.

BACKGROUND: Antibiotic resistance is increasingly complicating the management of urinary tract infection. We investigated the extent to which a group of Escherichia coli called clonal group A (CGA), which is associated with resistance to trimethoprim-sulfamethoxazole (TMP-SMZ), accounted for TMP-SMZ resistance among a prospectively collected set of uropathogenic and rectal E. coli isolates from a university population in Michigan. METHODS: Resistant and susceptible uropathogenic E. coli isolates (45 each) and 79 randomly selected rectal E. coli isolates were evaluated for CGA status by use of 2 definitions of this group-- the enterobacterial repetitive intergenic consensus sequence 2 (ERIC2)-polymerase chain reaction (PCR) pattern A fingerprint and the C288T single nucleotide polymorphism (SNP) in the fumC gene. We compared virulence gene profiles and molecular mechanisms of resistance to TMP-SMZ between isolates classified as CGA by both approaches to better characterize the relationship between isolates. RESULTS: Of the 45 isolates that exhibited ERIC2-PCR pattern A, one-half (23 of 45) were resistant to TMP-SMZ, and 16 contained the C288T SNP. The pattern A isolates were diverse, exhibiting multiple mechanisms of resistance to TMP-SMZ and various combinations of virulence factors. C288T SNP isolates showed less variation, with 15 of 16 resistant to TMP-SMZ and a 1.8-kb class I integron bearing the dfrA17 gene present in 14 of 15 resistant isolates. Twelve of 16 exhibited the same combination of virulence genes. Pulsed-field gel electrophoresis patterns for these 12 isolates were unique. CONCLUSION: CGA, as defined by the fumC C288T SNP, appears to be distantly clonal but is not an outbreak-related group. The widespread group has likely evolved through lateral transfer of genes conferring virulence and antibiotic resistance.

Adolescent↗
PubMed2005

Challenges of epidemiology in the 21st century: comments from the leaders of several epidemiology associations.

At the 2002 American Public Health Association Meeting, leaders of 12 epidemiology associations discussed the future challenges and epidemiology in the 21st century. A summary of the identified research-related, ethics, advocacy, training, and professional organization challenges is presented. Increased communication between all epidemiologists--regardless of specialty--is an excellent first step toward developing strategies to meet these challenges.

Epidemiology↗
PubMed2005

Temporal trends in sexual behaviors and sexually transmitted disease history among 18- to 39-year-old Seattle, Washington, residents: results of random digit-dial surveys.

OBJECTIVES: The objectives of this study were to describe sexual behaviors of Seattle residents in 2003-2004 and report changes since 1995. METHODS: We conducted a random digit-dial (RDD) survey among 18- to 39-year-old men and women in 2003-2004. We compared the results with the results of a 1995 RDD survey conducted in the same population. Questionnaire batteries and sampling methods were similar in the 2 surveys. RESULTS: Between 1995 and 2004, the median number of lifetime sex partners increased from 7 to 8. Vaginal douching declined from 70.6% to 25.9% (P = 0.004) among black women; from 8.3% to 5.9% (P <0.05) among Asian American women; and from 15.5% to 2.4% (P <0.05) overall. After adjustment, proportions of women who reported practicing vaginal douching (odds ratio [OR], 0.13; 95% confidence interval [CI], 0.7-0.22), the proportion of respondents who reported a history of any sexually transmitted disease (OR, 0.70; 95% CI, 0.53-0.93) and a history of gonorrhea (OR, 0.48; 95% CI, 0.25-0.89) declined between 1995 and 2004. Conversely, the proportion of respondents who reported only same-sex partners (OR, 3.27; 95% CI, 1.33-9.88), condom use at first sex with their most recent sex partner (OR, 1.38; 95% CI, 1.06-1.78), and reported practice of anal sex (OR, 2.01; 95% CI, 1.21-3.48) increased between 1995 and 2004. Among blacks, proportions reporting an age difference of only 2 years with their partners declined from 64.3% to 25.9% (P <0.05), indicating increased age mixing. CONCLUSIONS: Some risk behaviors declined whereas others increased between 1995 and 2004; several trends were divergent between the general population and minority populations. Our data hint at an increasing divergence in risk behaviors and morbidity between minority populations and the general population. Also, anal sex and number of sex partners have increased. These patterns have serious implications for the design, targeting, and implementation of prevention programs.

Adolescent↗