Werner E. Bischoff

Staphylococcus aureus nasal carriage in a student community: Prevalence, clonal relationships, and risk factors

OBJECTIVE To evaluate the prevalence and risk factors of nasal Staphylococcus aureus (SA) in the community. DESIGN Cross-sectional study. SETTING Wake Forest University, Winston-Salem, North Carolina. PARTICIPANTS Four hundred fifty students were screened for nasal SA carriage during the fall of 2000, 2001, and 2002. METHODS Students were screened by nose swabs. A self-administered questionnaire collected information on demographics and medical history. Antibiotic testing and PFGE were performed on isolates. Risk factors were determined by logistic regression analysis. RESULTS Of 450 volunteers, 131 (29%) were SA carriers. Antibiotic resistance was high for azithromycin (26%) and low for ciprofloxacin (1%), tetracycline (5%), mupirocin (1%), and methicillin (2%). PFGE patterns were not associated with carriage. Age, male gender, white race, medical student, allergen injection therapy, chronic sinusitis, rheumatoid arthritis, hospitalization for 6 months or less, and use of antibiotics were associated with carrier status by univariate analysis. Stepwise multivariate logistic regression led to a best fitting model with older age (OR, 1.04; CI95, 1.005-1.079), male gender (OR, 1.50; CI95, 0.982-2.296), and chronic sinusitis (OR, 2.71; CI95, 0.897-8.195) as risk factors. Antibiotic use (< 4 weeks) (OR, 0.41; CI95, 0.152-1.095) and allergen injection therapy (OR, 0.41; CI95, 0.133-1.238) were protective. Analyses of carriers revealed candidate factors for persistent carriage to be nasal SA colonization rate and male gender. Factors for azithromycin resistance were non-medical students and antibiotic use in the past 6 months. CONCLUSION Older male volunteers suffering from chronic sinusitis and not taking antibiotics were at higher risk for carrying SA.

Exposure to Influenza Virus Aerosols During Routine Patient Care

BACKGROUND Defining dispersal of influenza virus via aerosol is essential for the development of prevention measures. METHODS During the 2010-2011 influenza season, subjects with influenza-like illness were enrolled in an emergency department and throughout a tertiary care hospital, nasopharyngeal swab specimens were obtained, and symptom severity, treatment, and medical history were recorded. Quantitative impaction air samples were taken not ≤0.305 m (1 foot), 0.914 m (3 feet), and 1.829 m (6 feet) from the patients head during routine care. Influenza virus was detected by rapid test and polymerase chain reaction. RESULTS Sixty-one of 94 subjects (65%) tested positive for influenza virus. Twenty-six patients (43%) released influenza virus into room air, with 5 (19%) emitting up to 32 times more virus than others. Emitters surpassed the airborne 50% human infectious dose of influenza virus at all sample locations. Healthcare professionals (HCPs) were exposed to mainly small influenza virus particles (diameter, <4.7 µm), with concentrations decreasing with increasing distance from the patients head (P < .05). Influenza virus release was associated with high viral loads in nasopharyngeal samples (shedding), coughing, and sneezing (P < .05). Patients who reported severe illness and major interference with daily life also emitted more influenza virus (P < .05). CONCLUSIONS HCPs within 1.829 m of patients with influenza could be exposed to infectious doses of influenza virus, primarily in small-particle aerosols. This finding questions the current paradigm of localized droplet transmission during non-aerosol-generating procedures.

Migrant farmworker housing regulation violations in north Carolina

BACKGROUND The quality of housing provided to migrant farmworkers is often criticized, but few studies have investigated these housing conditions. This analysis examines housing regulation violations experienced by migrant farmworkers in North Carolina, and the associations of camp characteristics with the presence of housing violations. METHODS Data were collected in183 eastern North Carolina migrant farmworker camps in 2010. Housing regulation violations for the domains of camp, sleeping room, bathroom, kitchen, laundry room, and general housing, as well as total violations were assessed using North Carolina Department of Labor standards. RESULTS Violations of housing regulations were common, ranging from 4 to 22 per camp. Housing regulation violations were common in all domains; the mean number of camp violations was 1.6, of sleeping room violations was 3.8, of bathroom violations was 4.5, of kitchen violations was 2.3, of laundry room violations was 1.2, and of general housing violations was 3.1. The mean number of total housing violations was 11.4. Several camp characteristics were consistently associated with the number of violations; camps with workers having H-2A visas, with North Carolina Department of Labor Certificates of Inspection posted, and assessed early in the season had fewer violations. CONCLUSIONS These results argue for regulatory changes to improve the quality of housing provided to migrant farmworkers, including stronger regulations and the more vigorous enforcement of existing regulations.

Transocular Entry of Seasonal Influenza–Attenuated Virus Aerosols and the Efficacy of N95 Respirators, Surgical Masks, and Eye Protection in Humans

BACKGROUND The efficacy of barrier precautions to prevent influenza transmission is unknown. METHODS Twenty-eight participants were exposed to monodispersed live attenuated influenza vaccine (LAIV) particles (4.9 μm) in 6 groups: group 1, no precautions; group 2, ocular exposure only; group 3, surgical mask without eye protection; group 4, surgical mask with eye protection; group 5, fit-tested N95 respirator without eye protection; and group 6, fit-tested N95 respirator with eye protection. Influenza was detected by reverse-transcription polymerase chain reaction (RT-PCR) and culture in nasal washes. Exact 95% confidence intervals (CIs) were calculated. RESULTS Influenza was detected in 4 of 4 participants in group 1 (95% CI, 0-.60), 3 of 4 in group 2 (95% CI, .006-.806]), 5 of 5 in group 3 (95% CI, 0-.522), 5 of 5 in group 4, (95% CI, 0-.522), 3 of 5 in group 5 (95% CI, .053-.853), and 1 of 5 in group 6 (95% CI, .05-.72). RT-PCR revealed significant differences between group 1 and all other groups except group 3. CONCLUSIONS Transocular transmission of LAIV occured in most participants suggesting the necessity of eye protection. An N95 respirator provided the best guard further enhanced by eye protection.

HIV and sexually transmitted disease risk among male Hispanic/Latino migrant farmworkers in the Southeast: Findings from a pilot CBPR study

BACKGROUND Little is known about the HIV and sexually transmitted disease (STD) risk behaviors of Hispanic/Latino farmworkers. This study was designed to describe risk factors for HIV and STD infection, explore personal characteristics associated with condom use, and evaluate the feasibility of collecting self-report and biomarker data from farmworkers. METHODS Self-report and biomarker data were collected from a sample of male farmworkers living in 29 camps in North Carolina during the 2008 growing season. RESULTS Over half of the 100 male workers, mean age 37.1 (range 19-68) years, reported binge drinking during the past 12 months. Forty percent of those who reported having had sex during the past 3 months indicated that they were under the influence of alcohol. Knowledge of HIV and STD transmission and prevention was low. Among the 25 workers who reported having had sex during the past 3 months, 16 and 2 reported using a condom consistently during vaginal and anal sex, respectively, and nearly 1 out of 6 workers reported paying a woman to have sex. Two workers tested positive for syphilis. CONCLUSIONS Farmworkers in this sample demonstrated significant HIV and STD risks; however, when exploring potential bivariate associations with consistent condom use no statistically significant associations were identified perhaps due to the small sample size. Because it was feasible to collect self-report and biomarker data related to HIV and STDs from Hispanic/Latino farmworkers, research needed to further explore risks and develop interventions to reduce disease exposure and transmission among this vulnerable population.

“Gesundheit!” Sneezing, Common Colds, Allergies, and Staphylococcus aureus Dispersion

BACKGROUND Staphylococcus aureus is among the most important pathogens in todays hospital setting. METHODS The effects of sneezing on the airborne dispersal of S. aureus and other bacteria were assessed in 11 healthy nasal S. aureus carriers with experimentally induced rhinovirus colds. Airborne dispersal was studied by volumetric air sampling in 2 chamber sessions with and without histamine-induced sneezing. After 2 days of preexposure measurements, volunteers were inoculated with a rhinovirus and monitored for 14 days. Daily quantitative nasal- and skin-culture samples for bacteria and nasal-culture samples for rhinovirus were obtained, cold symptoms were assessed, and volunteer activities were recorded during sessions. RESULTS All participants developed a cold. Sneezing caused a 4.7-fold increase in the airborne dispersal of S. aureus, a 1.4-fold increase in coagulase-negative staphylococci (CoNS), and a 3.9-fold increase in other bacteria (P < .001). An additional 2.83 colony forming units (cfu) of S. aureus/m3/min, 3.24 cfu of CoNS/m3/min, and 474.61 cfu of other bacteria/m3/min were released per sneeze. Rhinovirus exposure did not change the frequency of sneezing or airborne dispersal. Having respiratory allergies increased the spread of S. aureus by 3.8-fold during sneezing sessions (P < .001). CONCLUSION Nasal S. aureus carriers disperse a significant amount of S. aureus into the air by sneezing. Experimental colds do not alter bacterial dispersal, but respiratory allergies multiply the effect of dispersing S. aureus.

Heat Index in Migrant Farmworker Housing: Implications for Rest and Recovery From Work-Related Heat Stress

Although the health risk to farmworkers of working in hot conditions is recognized, potential for excessive heat exposure in housing affecting rest and recovery has been ignored. We assessed heat index in common and sleeping rooms in 170 North Carolina farmworker camps across a summer and examined associations with time of summer and air conditioning use. We recorded dangerous heat indexes in most rooms, regardless of time or air conditioning. Policies to reduce heat indexes in farmworker housing should be developed.

Safety, security, hygiene and privacy in migrant farmworker housing.

Safety, security, hygiene, and privacy in migrant farmworker housing have not previously been documented, yet these attributes are important for farmworker quality of life and dignity. This analysis describes the safety, security, hygiene, and privacy of migrant farmworker housing and delineates camp characteristics that are associated with these attributes, using data collected in 183 eastern North Carolina migrant farmworker camps in 2010. Migrant farmworker housing is deficient. For example, 73.8 percent of housing had structural damage and 52.7 percent had indoor temperatures that were not safe. Farmworkers in 83.5 percent of the housing reported that they did not feel they or their possessions were secure. Bathing or toileting privacy was absent in 46.2 percent of the housing. Camps with residents having H-2A visas or North Carolina Department of Labor certificates of inspection posted had better safety, security, and hygiene. Regulations addressing the quality of migrant farmworker housing are needed.

Cooking and Eating Facilities in Migrant Farmworker Housing in North Carolina

OBJECTIVES We sought to (1) describe observed cooking and eating facilities in migrant farmworker camps, (2) compare observed conditions with existing farmworker housing regulations, and (3) examine associations of violations with camp characteristics. METHODS We collected data in 182 farmworker camps in eastern North Carolina during the 2010 agricultural season. We compared our observations with 15 kitchen-related housing regulations specified by federal and state housing standards. RESULTS We observed violations of 8 regulations in at least 10% of camps: improper refrigerator temperature (65.5%), cockroach infestation (45.9%), contaminated water (34.4%), rodent infestation (28.9%), improper flooring (25.8%), unsanitary conditions (21.2%), improper fire extinguisher (19.9%), and holes or leaks in walls (12.1%). Logistic regression showed that violations were related to the time of the agricultural season, housing type, number of dwellings and residents, and presence of workers with H-2A visas. CONCLUSIONS Cooking and eating facilities for migrant farmworkers fail to comply with regulations in a substantial number of camps. Greater enforcement of regulations, particularly during occupancy during the agricultural season, is needed to protect farmworkers.

Preventing the airborne spread of Staphylococcus aureus by persons with the common cold: effect of surgical scrubs, gowns, and masks.

OBJECTIVE Transmission of Staphylococcus aureus via air may play an important role in healthcare settings. This study investigates the impact of barrier precautions on the spread of airborne S. aureus by volunteers with experimentally induced rhinovirus infection (ie, the common cold). DESIGN Prospective nonrandomized study. SETTING Wake Forest University School of Medicine (Winston-Salem, NC).Participants. A convenience sample of 10 individuals with nasal S. aureus carriage selected from 593 students screened for carriage. INTERVENTION Airborne S. aureus dispersal was studied in the 10 participants under the following clothing conditions: street clothes, surgical scrubs, surgical scrubs and a gown, and the latter plus a face mask. After a 4-day baseline period, volunteers were exposed to a rhinovirus, and their clinical course was followed for 12 days. Daily swabs of nasal specimens, pharynx specimens, and skin specimens were obtained for quantitative culture, and cold symptoms were documented. Data were analyzed by random-effects negative binomial models. RESULTS All participants developed a common cold. Incidence rate ratios (IRRs) indicated that, compared with airborne levels of S. aureus during sessions in which street clothes were worn, airborne levels decreased by 75% when surgical scrubs were worn (P<.001), by 80% when scrubs and a surgical gown were worn (P<.001), and by 82% when scrubs, a gown, and a face mask were worn (P<.001). The addition of a mask to the surgical scrubs and gown did not reduce the airborne dispersal significantly (IRR, 0.92; P>.05). Male volunteers shed twice as much S. aureus as females (incidence rate ratio, 2.04; P=.013). The cold did not alter the efficacy of the barrier precautions. CONCLUSIONS Scrubs reduced the spread of airborne S. aureus, independent of the presence of a rhinovirus-induced cold. Airborne dispersal of S. aureus during sessions in which participants wore surgical scrubs was not significantly different from that during sessions in which gowns and gowns plus masks were also worn.