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The aim of this study was to elucidate risk factors, including ward antimicrobial use density (AUD), for central line-associated bloodstream infection (CLABSI) as defined by the Centers for Disease Control and Prevention in a 430-bed community hospital using central venous lines with closed-hub systems. We calculated AUD as (total dose)/(defined daily dose × patient days) ×1,000 for a total of 20 drugs, nine wards, and 24 months. Into each line day data, we inputed AUD and device utilization ratios, number of central line days, and CLABSI. The ratio of susceptible strains in isolates were subjected to correlation analysis with AUD. Of a total of 9,997 line days over 24 months, CLABSI was present in 33 cases (3.3 ‰), 14 (42.4%) of which were on surgical wards out of nine wards. Of a total of 43 strains isolated, eight (18.6%) were methicillin-resistant Staphylococcus aureus (MRSA); none of the MRSA-positive patients had received cefotiam before the onset of infection. Receiver-operating characteristic analysis showed that central line day 7 had the highest accuracy. Logistic regression analysis showed the central line day showed an odds ratio of 5.511 with a 95% confidence interval of 1.936-15.690 as did AUD of cefotiam showing an odds ratio of 0.220 with 95% confidence interval of 0.00527-0.922 (P=0.038). Susceptible strains ratio and AUD showed a negative correlation (R2=0.1897). Thus, CLABSI could be prevented by making the number of central line days as short as possible. The preventative role of AUD remains to be investigated. [ABSTRACT FROM AUTHOR]

It is not known whether or not ward-specific antimicrobial use density (AUD) affects the ratio of methicillin-resistant Staphylococcus aureus (MRSA) in culture-positive S. aureus. A 60-month study was attempted to ascertain the association between inpatient MRSA ratio and ward-specific AUDs as well as the former and latter study intervals, specimen types, and ward specialty. During the study, the professionals in infection control regulated the use of broad-spectrum antimicrobials and those for MRSA. By both month and ward, the ratio of inpatients positive for MRSA to those positive for S. aureus was calculated. Factors associated with MRSA ratio included AUDs averaged for the sampling month and its previous month, outpatient MRSA ratio by age, ward specialty, specimen type, and half intervals to represent historical changes. Of a total of 4,245 strains of S. aureus isolated during the 5-year study, 2,232 strains (52.6%) were MRSA. By year, outpatient MRSA ratio at age $15 decreased in later years, as did inpatient MRSA ratio. Multivariate analysis for inpatient MRSA ratio revealed a positive risk in AUDs for meropenem (odds ratio [OR] 1.761; 95% confidence interval [CI] 1.761-2.637, P = 0.01), imipenem-cilastatin (OR 1.583; 95% CI 1.087-2.306, P = 0.02), ampicillin-sulbactam (OR 1.623; 95% CI 1.114-2.365, P = 0.01), and minocycline (OR 1.680; CI 1.135-2.487, P = 0.01), respiratory care ward (OR 2.292; 95% CI 1.085-4.841, P = 0.03), and outpatient MRSA ratio (OR 1.536; 95% CI 1.070-2.206, P = 0.02). Use of broad-spectrum antimicrobials, such as meropenem, imipenem-cilastatin, and ampicillin-sulbactam may increase inpatient MRSA ratio. Ward factor should be included in MRSA surveillance because of the possible effect on AUD and considering patients' backgrounds. [ABSTRACT FROM AUTHOR]