A case control study of environmental and occupational exposures associated with methicillin resistant Staphylococcus aureus nasal carriage in patients admitted to a rural tertiary care hospital in a high density swine region

Background: Distinct strains of methicillin resistant Staphylococcus aureus (MRSA) have been identified on livestock and livestock workers. Industrial food animal production may be an important environmental reservoir for human carriage of these pathogenic bacteria. The objective of this study was to investigate environmental and occupational exposures associated with nasal carriage of MRSA in patients hospitalized at Vidant Medical Center, a tertiary hospital serving a region with intensive livestock production in eastern North Carolina. Methods: MRSA nasal carriage was identified via nasal swabs collected within 24 hours of hospital admission. MRSA carriers (cases) were gender and age matched to non-carriers (controls). Participants were interviewed about recent environmental and occupational exposures. Home addresses were geocoded and publicly available data were used to estimate the density of swine in residential census block groups of residence. Conditional logistic regression models were used to derive odds ratio (OR) estimates and 95% confidence intervals (CI). Presence of the scn gene in MRSA isolates was assessed. In addition, multi locus sequence typing (MLST) of the MRSA isolates was performed, and the Diversilab® system was used to match the isolates to USA pulsed field gel electrophoresis types. Results: From July - December 2011, 117 cases and 119 controls were enrolled. A higher proportion of controls than cases were current workforce members (41.2% vs. 31.6%) Cases had a higher odds of living in census block groups with medium densities of swine (OR: 4.76, 95% CI: 1.36-16.69) and of reporting the ability to smell odor from a farm with animals when they were home (OR: 1.51, 95% CI: 0.80-2.86). Of 49 culture positive MRSA isolates, all were scn positive. Twenty-two isolates belonged to clonal complex 5. Conclusions: Absence of livestock workers in this study precluded evaluation of occupational exposures. Higher odds of MRSA in medium swine density areas could reflect environmental exposure to swine or poultry

Medical and Household Characteristics Associated with Methicillin Resistant Staphylococcus aureus Nasal Carriage among Patients Admitted to a Rural Tertiary Care Hospital

BackgroundMethicillin resistant Staphylococcus aureus (MRSA) poses a threat to patient safety and public health. Understanding how MRSA is acquired is important for prevention efforts. This study investigates risk factors for MRSA nasal carriage among patients at an eastern North Carolina hospital in 2011.MethodsUsing a case-control design, hospitalized patients ages 18 – 65 years were enrolled between July 25, 2011 and December 15, 2011 at Vidant Medical Center, a tertiary care hospital that screens all admitted patients for nasal MRSA carriage. Cases, defined as MRSA nasal carriers, were age and gender matched to controls, non-MRSA carriers. In-hospital interviews were conducted, and medical records were reviewed to obtain information on medical and household exposures. Multivariable conditional logistic regression was used to derive odds ratio (OR) estimates of association between MRSA carriage and medical and household exposures.ResultsIn total, 117 cases and 119 controls were recruited to participate. Risk factors for MRSA carriage included having household members who took antibiotics or were hospitalized (OR: 3.27; 95% Confidence Interval (CI): 1.24–8.57) and prior hospitalization with a positive MRSA screen (OR: 3.21; 95% CI: 1.12–9.23). A lower proportion of cases than controls were previously hospitalized without a past positive MRSA screen (OR: 0.40; 95% CI: 0.19–0.87).ConclusionThese findings suggest that household exposures are important determinants of MRSA nasal carriage in hospitalized patients screened at admission

A case control study of environmental and occupational exposures associated with methicillin resistant Staphylococcus aureus nasal carriage in patients admitted to a rural tertiary care hospital in a high density swine region

Background: Distinct strains of methicillin resistant Staphylococcus aureus (MRSA) have been identified on livestockand livestock workers. Industrial food animal production may be an important environmental reservoir for humancarriage of these pathogenic bacteria. The objective of this study was to investigate environmental andoccupational exposures associated with nasal carriage of MRSA in patients hospitalized at Vidant Medical Center,a tertiary hospital serving a region with intensive livestock production in eastern North Carolina.Methods: MRSA nasal carriage was identified via nasal swabs collected within 24 hours of hospital admission.MRSA carriers (cases) were gender and age matched to non-carriers (controls). Participants were interviewed aboutrecent environmental and occupational exposures. Home addresses were geocoded and publicly available datawere used to estimate the density of swine in residential census block groups of residence. Conditional logisticregression models were used to derive odds ratio (OR) estimates and 95% confidence intervals (CI). Presence of thescn gene in MRSA isolates was assessed. In addition, multi locus sequence typing (MLST) of the MRSA isolates wasperformed, and the Diversilab® system was used to match the isolates to USA pulsed field gel electrophoresis types.Results: From July - December 2011, 117 cases and 119 controls were enrolled. A higher proportion of controlsthan cases were current workforce members (41.2% vs. 31.6%) Cases had a higher odds of living in census blockgroups with medium densities of swine (OR: 4.76, 95% CI: 1.36-16.69) and of reporting the ability to smell odor froma farm with animals when they were home (OR: 1.51, 95% CI: 0.80-2.86). Of 49 culture positive MRSA isolates, allwere scn positive. Twenty-two isolates belonged to clonal complex 5.Conclusions: Absence of livestock workers in this study precluded evaluation of occupational exposures. Higherodds of MRSA in medium swine density areas could reflect environmental exposure to swine or poultry

Open Access

A case control study of environmental and occupational exposures associated with methicillin resistant Staphylococcus aureus nasal carriage in patients admitted to a rural tertiary care hospital in a high density swine regio

Estimates of association of methicillin resistant <i>Staphylococcus aureus</i> (MRSA) nasal carriage identified by polymerase chain reaction with medical and household exposures from a multivariable logistic model conditioned on age and gender.

<p>Abbreviation: months, mo.; odds ratio, OR; confidence interval, CI.</p>a<p>Non-white or Hispanic includes non-Hispanic black, Hispanic/Latino, Asian, American Indian, or other race/ethnicities.</p>b<p>The gym visitation/sports participation variable reflects the 2 weeks prior to the hospital admission, even though 2 cases and 1 control were screened for MRSA 9 or more days before their current hospital admission.</p>c<p>Entered into the model as a 3-level categorical variable.</p

Medical and Household Characteristics Associated with Methicillin Resistant Nasal Carriage among Patients Admitted to a Rural Tertiary Care Hospital

Background Methicillin resistant Staphylococcus aureus (MRSA) poses a threat to patient safety and public health. Understanding how MRSA is acquired is important for prevention efforts. This study investigates risk factors for MRSA nasal carriage among patients at an eastern North Carolina hospital in 2011. Methods Using a case-control design, hospitalized patients ages 18 – 65 years were enrolled between July 25, 2011 and December 15, 2011 at Vidant Medical Center, a tertiary care hospital that screens all admitted patients for nasal MRSA carriage. Cases, defined as MRSA nasal carriers, were age and gender matched to controls, non-MRSA carriers. In-hospital interviews were conducted, and medical records were reviewed to obtain information on medical and household exposures. Multivariable conditional logistic regression was used to derive odds ratio (OR) estimates of association between MRSA carriage and medical and household exposures. Results In total, 117 cases and 119 controls were recruited to participate. Risk factors for MRSA carriage included having household members who took antibiotics or were hospitalized (OR: 3.27; 95% Confidence Interval (CI): 1.24–8.57) and prior hospitalization with a positive MRSA screen (OR: 3.21; 95% CI: 1.12–9.23). A lower proportion of cases than controls were previously hospitalized without a past positive MRSA screen (OR: 0.40; 95% CI: 0.19–0.87). Conclusion These findings suggest that household exposures are important determinants of MRSA nasal carriage in hospitalized patients screened at admission