Community-associated methicillin-resistant Staphylococcus aureus: trends in case and isolate characteristics from six years of prospective surveillance.

OBJECTIVES: In 2000, the Minnesota Department of Health (MDH) implemented active, sentinel site surveillance for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Data from 2000-2005 were analyzed to determine trends in case characteristics, pulsed-field types (PFTs), and antimicrobial susceptibilities including inducible clindamycin resistance (ICR). METHODS: Active sentinel site surveillance was initiated in 2000 at 12 hospital laboratories that served inpatients and outpatients. Patient medical records were reviewed to determine if they met the epidemiologic case criteria for CA-MRSA; isolates were obtained from patients meeting these criteria. The MDH Public Health Laboratory performed pulsed-field gel electrophoresis subtyping and antimicrobial susceptibility testing, including ICR. RESULTS: The proportion of MRSA cases classified as CA increased from 11% to 33% (p<0.01). The proportion of cases with skin or soft tissue infections also increased compared with other infection types from 75% to 87% (p<0.01). During the surveillance period, USA300 replaced USA400 as the dominant PFT. With the change in dominant PFT, the proportion of isolates susceptible to erythromycin (45% to 13%, p<0.01) and ciprofloxacin (80% to 59%, p<0.01) decreased. The proportion of erythromycin-resistant/clindamycin-susceptible isolates with ICR (93% to 14%, p<0.01) decreased. The proportion of susceptible isolates also changed within the USA300 PFT; the proportion of isolates susceptible to erythromycin (33% vs. 3%) and the proportion susceptible to ciprofloxacin (67% to 62%) decreased significantly. CONCLUSION: CA-MRSA increased dramatically from 2000 to 2005. Changes in the predominant PFT have impacted susceptibility profiles of CA-MRSA, including ICR. Continued surveillance is needed to monitor the changing epidemiology of CA-MRSA and to inform clinical decisions.

A community outbreak of conjunctivitis caused by nontypeable Streptococcus pneumoniae in Minnesota.

BACKGROUND: The Minnesota Department of Health (MDH) was notified of an outbreak of conjunctivitis in city A with cultures positive for Streptococcus pneumoniae. METHODS: MDH staff contacted clinics and schools in city A and city B regarding conjunctivitis cases, reviewed clinical findings of conjunctivitis cases in city A and collected isolates for subtyping. RESULTS: Between September 1 and December 12, 2003, cities A and B reported 735 conjunctivitis cases. Fifty-one percent of the cases were reported from schools, childcare centers and colleges. Adults were more likely to report itching, burning or swelling of the eye(s); children were more likely to report crusty eyes (P < 0.05). Forty-nine percent of conjunctival cultures (71 of 144) were positive for S. pneumoniae. All isolates were nontypeable by serotyping. Pulsed field gel electrophoresis identified 3 clonal groups with 84% of isolates belonging to one clonal group. Multilocus sequence typing revealed that isolates had the same multilocus sequence type as isolates from a 2002 outbreak at a New England college. CONCLUSIONS: This outbreak was widespread in the community and conjunctivitis clinical presentation varied by age. The predominant strains in this outbreak were related to a pneumococcal strain implicated in prior conjunctivitis outbreaks, suggesting these strains have a predilection for causing conjunctivitis.

Effect of age and degree of immune activation on cytochrome P450 3A4 activity after influenza immunization.

STUDY OBJECTIVE: To measure age- or sex-related changes in cytochrome P450 (CYP) activity secondary to influenza vaccination. DESIGN: Open-label, single-dose study. SETTING: General clinical research center at a university hospital. SUBJECTS: Fifteen healthy volunteers aged 22-51 years. INTERVENTION: Each subject was given an erythromycin breath test (ERMBT) to measure CYP3A4 activity before influenza immunization and again on day 7 after immunization. Blood was drawn before immunization and on day 28 after immunization to measure influenza antibody concentrations. MEASUREMENTS AND MAIN RESULTS: Age of subject and change in ERMBT results after influenza immunization were correlated (correlation coefficient -0.624, p < 0.015). However, no correlations could be made between antibody concentrations after influenza immunization or change in antibody concentrations from baseline and age. CONCLUSION: Decreases in CYP3A4 activity after influenza immunization are associated with increasing age. The decreases in CYP3A4 activity, however, are not associated with influenza antibody concentrations. This study bears repeating in an older cohort since the study sample did not include elderly individuals.

Production of interferon-gamma and interleukin-10 after inactivated hepatitis A immunization.

STUDY OBJECTIVE: To assess helper T cell function by measuring cytokine production over time after hepatitis A immunization. DESIGN: Open-label, single-dose study. SETTING: General clinical research center of a university hospital. SUBJECTS: Twenty-five healthy adults. INTERVENTION: Each subject was immunized with inactivated hepatitis A vaccine; blood was drawn on day 0 (the day of immunization) and days 2, 5, 7, 10, and 28 after immunization. MEASUREMENTS AND MAIN RESULTS: Production of interferon (IFN)-gamma and interleukin (IL)-10 by peripheral blood mononuclear cells stimulated in culture with hepatitis A virus was measured by enzyme-linked immunosorbent assay. Concentrations of hepatitis A antibody were measured on day 28. Both IFN-gamma and IL-10 production peaked on day 10 after immunization (IFN-gamma day 0 median = 7.35 pg/ml, interquartile ratio [IQR] = 20.8 vs day 10 median = 22.35 pg/ml, IQR = 42.4, p < 0.05; IL-10 day 0 median = 1.00, IQR = 7.4 vs day 10 median = 11.75 pg/ml, IQR = 92.3, p < 0.02, Wilcoxon signed rank test). The IL-10:IFN-gamma ratio on day 10 correlated with antibody production (Pearson product moment correlation 0.46, p < 0.05). This ratio was used as a measure of helper T cell phenotype. CONCLUSION: Both IFN-gamma and IL-10 are produced in response to hepatitis A vaccine. The parallel production after immunization may contribute to the high efficacy of these vaccine preparations in inducing both cell-mediated immune response and a protective antibody response.

Tetanus seroprevalence among farmers: a preliminary study.

BACKGROUND: Farmers are at increased risk of contracting tetanus. However, no difference in immunity to tetanus has been reported between rural and urban dwellers in large epidemiological studies. We hypothesized that tetanus antibody concentrations would be lower in farmers than in nonfarmers within the rural population. METHODS: We recruited 102 adult subjects attending an agribusiness trade show who identified themselves as farmers in Wisconsin. The nonfarmer group (n = 120) was composed of adults attending the agribusiness show who were not engaged in farming or were participating in another research study. Concentrations of antibody to tetanus toxin (antiTT) in sera were measured by an enzyme-linked immunosorbent assay (IBL, Hamburg). AntiTT levels of >0.15 IU/mL were considered protective. RESULTS: The antiTT concentrations for the farmer population (median = 2.74 IU/mL) were much higher than those for the nonfarmer group (median = 1.82 IU/mL) (P<.008). As in other studies, being male, being younger, and having a history of military service were positively correlated with protective antiTT concentrations. However, only farming, age, and the farming-sex interaction term were significantly associated with antiTT concentrations in the multiple-regression model. CONCLUSIONS: The farmers we studied had high antiTT concentrations and a high tetanus seroprevalence rate. Occupation may be an important consideration in the development of immunization policies. A broader seroepidemiological study of farmers must be undertaken before any such considerations can be made.

Community-associated methicillin-resistant Staphylococcus aureus, Minnesota, 2000-2003.

We compared characteristics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections (SSTIs) and CA-MRSA invasive disease identified in Minnesota from 2000 through 2003. A total of 586 patients with SSTIs and 65 patients with invasive disease were identified. Patients with invasive disease were more likely to be smokers (p = 0.03), and report a history of immunosuppressive therapy (p = 0.03), emphysema (p = 0.011), or injection drug use (p = 0.020) than were SSTI patients. Invasive disease isolates were less likely to be susceptible to ciprofloxacin (p = 0.002) and clindamycin (p = 0.001) and more likely to have healthcare-associated pulsed-field gel electrophoresis subtypes than SSTI isolates (p<0.001). Patients with invasive disease may have had healthcare exposures that put them at risk of acquiring healthcare-associated MRSA and which were not exclusion criteria in the CA-MRSA case definition. Continued surveillance of MRSA is needed to better characterize CA-MRSA infections.

The association between psychosocial factors and vaccine-induced cytokine production.

Existing data suggest that immune function is compromised by negative psychosocial factors. We hypothesized that high psychological well being and quality relationships would be associated with vigorous cytokine responses to vaccination. Lymphocytes from 18 individuals were studied for their ability to produce interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) with influenza or hepatitis A immunization. Psychological well being and relationship quality were measured using standardized scales. Significant positive correlations were made between psychological well being and quality relationships and IFN-gamma and IL-10 production to influenza and hepatitis A on day 28 (Pearson correlations: 0.6-0.7; P<0.05). This preliminary study represents one of the first to show positive physiological health is associated with positive psychosocial factors.