Observations Relating to an Inter-Hospital Outbreak of Methicillin-Resistant Staphylococcus aureus: Role of Antimicrobial Therapy in Infection Control

Abstract

Clinical, bacteriologie, epidemiologic and hospital infection-control observations related to an inter-hospital outbreak of methicillin-resistant Staphylococcus aureus are described. The outbreak involved 66 patients at the University of Oregon Health Sciences Center (UOHSC) and its closely affiliated VA hospital, the Portland VA Medical Center (PVAMC). No environmental source of infection was identified; person-to-person transmission was most likely responsible for its spread. Surveillance cultures demonstrated nasal colonization in house staff and nursing personnel at both hospitals. Inter-hospital transfer of infection was, in all likelihood, achieved via nasal carriage by a single physician. Case-control analysis indicated a significantly increased risk (p < 0.05) of acquisition of infection related to age, number of days hospitalized, severity of underlying disease and number of invasive procedures. Prior antibiotic receipt was a significant risk factor when analyzed by univariate analysis (p < 0.01), but, in contrast to previous studies, this was not a significant risk factor (p > 0.05) when related variables were controlled by multivariate analysis. Prevention of spread of infection by routine infection control measures was less effective at PVAMC than at UOHSC. Patients at PVAMC were significantly older and had longer durations of hospitalization (p < 0.05). Antimicrobial therapy of colonized patients and personnel appeared to assist in the control of the outbreak at PVAMC. Antimicrobial therapy with topical bacitracin and oral rifampin, alone or in combination with oral trimethoprim-sulfamethoxazole, was effective in eliminating colonization with methicillin-resistant S. aureus. [Infect Control 1981; 2(6):453-459.]

Length of exposure to the hospital environment is more important than antibiotic exposure in healthcare associated infections by methicillin-resistant Staphylococcus aureus: a comparative study

“…These two factors, especially the former, are, without any doubt, among the strongest predictors of MRSA infections in older and newer studies. 4,[9][10][11][12][13][14][15][16][17][18][20][21][22][23][25][26][27][28]33,34 Obviously, differences in our results compared to the above-described studies may be partly due to different study design and differences in populations studied, as noted in a recent meta-analysis. 38 Additionally, from a subanalysis of the blood isolates of our study groups, the mean number of antibiotic-days did emerge as independent predictor of a subsequent HCA-MRSA bacteremia.…”

“…These results are in agreement with prior studies, looking at qualitative use of those antibiotics. 6,11,12,14,22,[26][27][28][29][33][34][35][36][37][38] Additionally, use of at least two different antibiotics during the previous month was at the border of statistical significance. The underlying mechanisms have not been completely clarified but several lines of evidence exist.…”

Methicillin-resistant staphylococci

“…Trimethoprim-sulfamethoxazole in combination with rifampin has been used to eradicate the nasal carriage of resistant staphylococci in nosocomial epidemics (163). The role of this combination for serious infections has not been defined, but it may be another alternative to vancomycin.…”

Combined Topical and Oral Antimicrobial Therapy for the Eradication of Methicillin‐Resistant Staphylococcus aureus (Mrsa) Colonization in Hospitalized Patients

“…Although this approach has been used successfully in the management and control of MRSA outbreaks, occasionally, when other measures appear to have failed (6)(7)(8)11,(16)(17)(18)(19)(20)(21)(22)(23), decolonization therapy is controversial. There are concerns regarding the effectiveness of the strategy and the emergence of antimicrobial resistance to the agents used (4,(24)(25)(26)(27).…”