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

Abstract

Objectives: Both total antimicrobial use and specific antimicrobials have been implicated as risk factors for healthcare-associated methicillin-resistant Staphylococcus aureus (HCA-MRSA) infection. The aims of this study were: (I) to explore predictors of a new HCA-MRSA infection in comparison with a new healthcare-associated methicillin-sensitive Staphylococcus aureus (HCA-MSSA); (II) to thoroughly assess the role of recent antibiotic use qualitatively and quantitatively. Methods: The time-period for our study was from October 1997 through September 2001. Through applying strict criteria, we identified two groups of inpatients, one with a new HCA-MRSA infection and one with a new HCA-MSSA infection. We recorded demographic, clinical and antibiotic use-related data up to 30 days before the positive culture date. Results: We identified 127 and 70 patients for each group, respectively. Two logistic regression models were carried out to assess the role of antimicrobial use (qualitatively and quantitatively). In model I, duration of hospital stay, presence of chronic wounds, aminoglycoside and fluoroquinolone use retained statistical significance. In model II, duration of hospital stay and history of intubation during the last month stood out as the only significant predictors of a subsequent HCA-MRSA infection. No significant differences in outcome were noted. Conclusions: The length of exposure to the hospital environment may be the best predictor of a new HCA-MRSA infection. Use of aminoglycosides and fluoroquinolones may also stand independently along with presence of chronic ulcers and surgical procedures. No independent association between quantitative antibiotic use and subsequent HCA-MRSA infection was documented. Keywords: methicillin-resistant Staphylococcus aureus; Staphylococcus aureus; antibacterial agents; fluoroquinolones. significant risk factor for MRSA acquisition and infection from most, but not all, case-control and cohort studies. 4,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Both total antimicrobial use as well as specific antimicrobial classes have been implicated. [11][12][13][14][15][16][17][18]24,25 Included in these classes are β-lactamic antibiotics, 14,26-33 cephalosporins, 11,12,16,22,29 aminoglycosides, 22,33,34 macrolides, 27 glycopeptides 15,[27][28][29]34 and fluoroquinolones (FQs). 6,11,12,14,[26][27][28][29][35][36][37] A relatively recently published meta-analysis detected a clear association between exposure to antibiotics and MRSA isolation. Significant risk ratios were found for FQs, glycopeptides, cephalosporins and other β-lactams. 38 A prediction model, aimed at identifying MRSA bacteremia, predicted that 80% of the nosocomial bacteremias would be resistant to methicillin if patients had experienced antimicrobials prior to the onset. This model also indicated that there were no differences between antibiotics in the prediction of MRSA. 29

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients

“…These results agree with those reported in other countries, however, in studies performed with patients treated at the hospital 28,34 . It was observed that oxacillin-resistant S. aureus has an associated resistance to ciprofloxacin (53.1%), sulfamethoxazole-trimethoprim (53.5%) and rifampicin (24.8%) 25 .…”

Hospital infections in a neurological intensive care unit: incidence, causative agents and risk factors

“…Our study indicates that prolonged hospital stay is a risk factor for the development of HIs, which is the same result obtained in several prior studies [32,33]. It has been demonstrated that hospital stay itself poses approximately 17.6% risk of hospital infection development, with each night spent in hospital increasing the risk by an additional 0.5% [34].…”

Risk factors for health care–associated infection in hospitalized adults: Systematic review and meta-analysis

“…In the cohort studies, the observed extrinsic RFs were central venous catheter (CVC) placement, 23,25,[50][51][52][53] ICU admission, [54][55][56][57][58] duration of surgery, 13,17,20,24 steroid use, 13,15,59 previous antibiotic use, 55,60 exposure to cephalosporins before the first episode of infection, 58,61 number of administered antibiotics, 53,62 antimicrobial therapy within 90 days, 63 reoperation, 20,64 transfusion, 50,56,64 invasive mechanical ventilation (IMV), 50,52,65 hospitalization time, 66,67 and a high score on the Acute Physiology and Chronic Health Disease Classification System II. 14,55 Other less frequent extrinsic RFs were found ( Supplementary Table S1).…”