Active surveillance to determine the impact of methicillin resistance on mortality in patients with bacteremia and influences of the use of antibiotics on the development of MRSA infection

Abstract

Revista da Sociedade Brasileira de Medicina Tropical 46(6):713-718, Nov-Dec, 2013http://dx.doi.org/10. ABSTRACT Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is among the most important pathogens of nosocomial infections, mainly in intensive care units (ICUs), and accounts for 40-60% of all healthcare-associated S. aureus infections. We evaluated the incidence of nosocomial infection by S. aureus, identifi ed the risk factors for MRSA infection, and evaluated the effect of resistance to methicillin on mortality in patients. Methods: We conducted MRSA surveillance at a university hospital in Brazil from January 1, 2010, to December 31, 2010, and performed a retrospective case-control matched study to evaluate the frequency of subsequent MRSA bacteremia and death among patients. We evaluated and compared the risk factors between patients with MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infection. Results: Sepsis was the most common cause of infection (17.7/1,000 patient-days), followed by surgical site (11.4/1,000 patient-days), pneumonia (4.1/1,000 patient-days), and urinary tract infection (2.4/1,000 patient-days). The signifi cant risk factors were time of hospitalization, use of central vascular catheter (CVC), urinary catheter, nasogastric tube, parenteral nutrition, tracheostomy, mechanical ventilation, and previous antibiotic administration, the latter of which was the only independent risk factor for MRSA infection. Mortality was signifi cantly higher in patients with MRSA. The number of antibiotics tested was not related to increases in the frequency of MRSA/1,000 patient-days. The incidence of mortality attributable to MRSA (bloodstream infection) BSI was 50%. Conclusions: Surveillance results showed that the use of high levels of antibiotics was directly related to the development of MRSA infection, and the mortality attributable to MRSA in patients with bacteremia was signifi cant.

Analysis of the Effects of Cigarette Smoke on Staphylococcal Virulence Phenotypes

“…aureus is a Gram-positive coccus that causes a broad range of infections, including invasive disease such as pneumonia, bacteremia, and endocarditis (7). Methicillin-resistant S. aureus (MRSA) is associated with a higher mortality rate in invasive infections than methicillin-sensitive S. aureus (MSSA) (8)(9)(10). Also, in severe staphylococcal pneumonia, MRSA outnumbers MSSA as the pathogen, accounting for 57% of cases (11).…”

Risk factors for methicillin-resistant Staphylococcus aureus bacteremia: A multicenter matched case-control study

“…The presence of comorbidities and the immunological status of patients have been presented previously as risk factors for the presence and prognosis of MRSA as a causal agent of bacteremia (9,10). Nevertheless, this was not proven in the study population.…”

“…In Latin America, a study by Porto, et al demonstrated a similar relationship between the presence of MRSA and the use of high dosages of cephalosporins, carbapenems and vancomycin as a monotherapy or in combination (10). As shown in figure 1, we independently identified the effects of the different types of antibiotics on the emergence of MRSA.…”

“…The study by Porto, et al also determined that a history of vascular, respiratory and gastric catheters represented a risk factor (10). The increased risk of MRSA infection can be explained by factors such as bacterial colonization of devices, greater exposure to manipulation and therefore to cross-transmission, and increased exposure to the use of prophylactic antimicrobials which could have a selective effect on the microorganism.…”

“…MRSA bacteremia emergence among ICU patients has been associated with several factors, which can be classified according to three groups: a) those related to the microorganisms, primarily the spread of resistant clones (8); b) those associated with the host, which include age, sex, presence of comorbidities (particularly chronic illnesses), previous use of antibiotics and invasive devices (9)(10)(11)(12), and c) the characteristics of hospital and community environments (9,11,13), particularly previous use of antibiotics given the high risk associated with this factor and the control of crosstransmission of microorganisms.…”