Shannon D. Manning

Group B Streptococcus Colonization in Male and Nonpregnant Female University Students: A Cross-Sectional Prevalence Study

We describe the prevalence of colonization with group B Streptococcus species in a random sample of otherwise healthy male and nonpregnant female college students. Colonization with group B Streptococcus species occurs at a high frequency among healthy students, and there was a suggestion that it is associated with having engaged in sexual activity, tampon use, milk consumption, and hand washing done < or =4 times per day. However, larger studies are needed to verify these findings.

VARIATIONS IN 10 PUTATIVE UROPATHOGEN VIRULENCE GENES AMONG URINARY, FAECAL AND PERI-URETHRAL ESCHERICHIA COLI

A total of 868 isolates was screened from seven different collections of organisms from previous studies - pyelonephritis in children aged 1-24 months; first, second and recurring urinary tract infection (UTI) in women aged 18-39 years; UTI in women aged 40-65 years and peri-urethral and faecal isolates from women aged 18-39 years - for the presence of 10 potential Escherichia coli UTI virulence genes. Previously reported differences between the frequency of these genes in UTI compared with faecal isolates were confirmed and extended. A single virulence signature (strains containing aer, kpsMT, ompT, fim and papGAD) occurred in 29% of the pyelonephritic isolates, but in no more than 11% of the other collections. Peri-urethral isolates were found to have frequencies of these 10 genes that differed from those found for both UTI and faecal isolates.

Prevalence of Group B Streptococcus Colonization and Potential for Transmission by Casual Contact in Healthy Young Men and Women

Group B Streptococcus (GBS) causes disease in newborns, pregnant women, and adults with underlying medical conditions, but it is also a commensal organism that commonly colonizes the bowel. In this study, the prevalence of colonization was high among 241 women (34%) and 211 men (20%) living in a college dormitory; sexually experienced subjects had twice the colonization rates of sexually inexperienced participants. Other predictors of colonization varied by colonization site. Only 10 of the 142 roommate pairs had roommates who were both colonized with GBS, and 20% of these pairs shared identical strains, which is the same rate predicted by the population distribution. By contrast, a previous report found that 86% of co-colonized sex partners shared identical strains. GBS is likely transmitted by intimate contact, but transmission modes may vary by colonization site. Large prospective studies are needed to better understand colonization site-specific factors for GBS and to clarify potential transmission modes.

Correlates of antibiotic-resistant group B streptococcus isolated from pregnant women ☆

OBJECTIVE: Despite antibiotic prophylaxis for at‐risk mothers during labor and delivery, group B streptococcus still causes substantial morbidity and mortality among newborns. Resistance to antibiotics recommended for penicillin‐allergic pregnant women, such as erythromycin and clindamycin, has increased. A better understanding of factors associated with group B streptococcus resistance is essential to effectively prevent group B streptococcus disease. METHODS: A total of 117 sequential group B streptococcus isolates were obtained between August 1999 and March 2000 from pregnant women at the University of Michigan Medical Center. Serotype and susceptibility to ten antimicrobials using disk diffusion with E‐test for confirmation were determined, and the association between several host factors and colonization with a resistant strain was evaluated. RESULTS: Group B streptococcus was frequently resistant to erythromycin (29%) and clindamycin (21%) but was susceptible to all other antimicrobials tested. A stepwise logistic regression model revealed that black ethnicity (P = .02) and carriage of a serotype V strain (P = .01) were associated with group B streptococcus resistance. CONCLUSION: Among this population of pregnant women, black ethnicity and serotype V were the strongest predictors of colonization with an erythromycin‐ or clindamycinresistant group B streptococcus strain. A better understanding of factors associated with antibiotic resistance is needed to minimize group B streptococcus disease risks and to maximize effective chemoprophylaxis. (Obstet Gynecol 2003;101:74‐9.

Frequency of antimicrobial resistance among invasive and colonizing Group B Streptococcal isolates

BackgroundGroup 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.MethodsWe 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 hybridizationResults20.0% (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.ConclusionClindamycin 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.

Comparison of DNA Dot Blot Hybridization and Lancefield Capillary Precipitin Methods for Group B Streptococcal Capsular Typing

ABSTRACT Group B streptococci (GBS) (Streptococcus agalactiae) are a major cause of sepsis and meningitis in neonates and infants and of invasive disease in pregnant women, nonpregnant, presumably immunocompromised adults, and the elderly. Nine GBS serotypes based on capsular polysaccharide antigens have been described. The serotype distributions among invasive and colonizing isolates differ between pediatric and adult populations and have changed over time. Thus, periodic monitoring of GBS serotype distributions is necessary to ensure the proper formulation and application of an appropriate GBS vaccine for human use and to detect the emergence of novel serotypes. Since the mid-1990s, the proportion of GBS isolates that are nontypeable by standard serologic methods has increased, creating a need for more sensitive typing methods. We describe a typing method that uses DNA dot blot hybridization with probes generated by PCR from the GBS capsular genes for serotypes Ia, Ib, and II to VIII. PCR primers were designed to amplify type-specific GBS capsular gene sequences. Gene probes were constructed from the PCR products and used to classify isolates based on hybridization profiles. A total of 306 previously serotyped invasive and colonizing isolates were used to compare our dot blot capsular typing (DBCT) identification method with Lancefield serotyping (LS). A dot blot capsular type was assigned to 99% (303 of 306) of the isolates, whereas 273 of 306 isolates (89%) were assigned a Lancefield serotype. The overall agreement between the methods was 95% (256 of 270 isolates typeable by both methods). We conclude that the DBCT method is a specific and useful alternative to the commonly used LS method.

Molecular epidemiologic approaches to urinary tract infection gene discovery in uropathogenic Escherichia coli.

ABSTRACT Urinary tract infection (UTI) is one of the most frequently acquired bacterial infections. The vast majority of UTIs are caused by a large, genetically heterogeneous group of Escherichia coli. This genetic diversity has hampered identification of UTI-related genes. A three-step experimental strategy was used to identify genes potentially involved in E. coli UTI transmission or virulence: epidemiologic pairing of a UTI-specific strain with a fecal control, differential cloning to isolated UTI strain-specific DNA, and epidemiologic screening to identify sequences among isolated DNAs that are associated with UTI. The 37 DNA sequences initially isolated were physically located all over the tester strain genome. Only two hybridized to the total DNA of the sequencedE. coli K-12 strain; eight sequences were present significantly more frequently in UTI isolates than in fecal isolates. Three of the eight sequences matched to genes for multidrug efflux proteins, usher proteins, and pathogenicity island insertion sites, respectively. Using population characteristics to direct gene discovery and evaluation is a productive strategy applicable to any system.

Determinants of co-colonization with group B streptococcus among heterosexual college couples.

Background. Group B Streptococcus causes morbidity and mortality among newborns, pregnant women, and nonpregnant adults. Among adults, sexual and fecal-oral routes of transmission are hypothesized; this study addresses whether sexual transmission occurs. Methods. Our outcome of interest was group B Streptococcus. From our investigation of the heterosexual transmission of urinary tract infections among college students at the University of Michigan, conducted in 1996–1999, we identified 120 couples in which one or both partners carried group B Streptococcus. Each partner completed a questionnaire regarding potential risk factors for colonization. Results. Co-colonization with the identical group B Streptococcus strain (as determined by pulsed-field gel electrophoresis) occurred in 86% of the 57 co-colonized couples. When the male sex partner carried group B Streptococcus, 64% of female partners also were colonized; conversely, 49% of male partners of colonized females were colonized with identical strains. Among behaviors predicting co-colonization within the partnership, male-to-female oral sex was a risk factor among both women (odds ratio [OR] = 2.9; 95% confidence interval [CI] = 1.2–6.9) and men (OR = 2.5; CI = 1.1–5.6). First sex at age 20 years or older was associated with an increased risk among women (OR = 2.1; CI = 0.7–6.4) and among men (OR = 3.0; CI = 1.0–9.3), and four or more lifetime sex partners was associated with a decreased risk of co-colonization among women (OR = 0.6; CI = 0.2–1.5) and among men (OR = 0.4; CI = 0.2–1.0). Conclusions. Among heterosexual college couples, sexual activity, particularly male-to-female oral sex, increases the risk of co-colonization with an identical group B Streptococcus strain. Future studies should evaluate the role of the pharynx and examine the effects of both bacterial characteristics and host response on transmission.

Prevalence of known P-fimbrial G alleles in Escherichia coli and identification of a new adhesin class.

ABSTRACT Screening a large Escherichia coli collection for P-fimbrial adhesin classes identified 20 unclassifiable strains. Cloning and sequencing of papG from an unclassifiable strain identified another G allele. The novel adhesin gene has 65% identity to the class I adhesin gene, 44% identity to the class II adhesin gene, and 43% identity to the class III adhesin gene.

Frequency of Antibiotic Resistance among Group B Streptococcus Isolated from Healthy College Students

We report resistant rates to erythromycin and clindamycin among Streptococcus agalactiae (group B Streptococcus) isolated from a random sample of healthy male and nonpregnant female college students. Observed resistance rates were twice as high as those reported among pregnant women from the same geographic area 2 years prior.