Miquel Pujol

Nosocomial Staphylococcus aureus bacteremia among nasal carriers of methicillin-resistant and methicillin-susceptible strains

OBJECTIVES To determine the relevance of nasal carriage of Staphylococcus aureus, either methicillin-sensitive (MSSA) or methicillin-resistant (MRSA), as a risk factor for the development of nosocomial S aureus bacteremia during an MRSA outbreak. PATIENTS AND METHODS In this prospective cohort study, 488 patients admitted to an intensive care unit (ICU) during a 1-year period were screened with nasal swabs within 48 hours of admission and weekly thereafter in order to identify nasal S aureus carriage. Nasal staphylococcal carriers were observed until development of S aureus bacteremia, ICU discharge, or death. RESULTS One hundred forty-seven (30.1%) of 488 patients were nasal S aureus carriers; 84 patients (17.2%) harbored methicillin-sensitive S aureus; and 63 patients (12.9%) methicillin-resistant S aureus. Nosocomial S aureus bacteremia was diagnosed in 38 (7.7%) of 488 patients. Rates of bacteremia were 24 (38%) of the MRSA carriers, eight (9.5%) of the MSSA carriers, and six (1.7%) of noncarriers. After adjusting for other predictors of bacteremia by means of a Cox proportional hazard regression model, the relative risk for S aureus bacteremia was 3.9 (95% confidence interval, 1.6-9.8; P = 0.002) for MRSA carriers compared with MSSA carriers. CONCLUSIONS Among ICU patients, nasal carriers of S aureus are at higher risk for S aureus bacteremia than are noncarriers; in the setting of an MRSA outbreak, colonization by methicillin-resistant strains represents a greater risk than does colonization by MSSA and strongly predicts the occurrence of MRSA bacteremia.

Relationship between quinolone use and emergence of ciprofloxacin-resistant Escherichia coli in bloodstream infections.

From 1988 to 1992, 27 of 855 cases of Escherichia coli bacteremia in nonneutropenic adult patients observed at our hospital were due to ciprofloxacin-resistant (CIPRO-R) strains. Eighteen episodes (67%) were community acquired, and nine (33%) were nosocomially acquired. Overall, the rates of E. coli bacteremia caused by CIPRO-R strains increased steadily from 0% in 1988 to 7.5% in 1992 (P < 0.01). There was a statistically significant correlation between the incidence of CIPRO-R E. coli bacteremia and the upward trend in fluoroquinolone (norfloxacin and ciprofloxacin) use in the community (r = 0.974; P = 0.005) as well as in the hospital (r = 0.975; P = 0.005). When we compared the 27 case patients with 54 simultaneous control patients who had ciprofloxacin-susceptible E. coli bacteremia, the case patients more frequently had chronic underlying diseases (71 versus 37%; P = 0.004), urinary tract infection (74 versus 50%; P = 0.03), prior surgery (22 versus 6%; P = 0.02), and prior fluoroquinolone use (63 versus 4%; P < 0.001). A logistic regression analysis identified prior quinolone use as the only independent risk factor for CIPRO-R E. coli bacteremia. In conclusion, our study shows a significant correlation between ciprofloxacin resistance and fluoroquinolone use and indicates that prior fluoroquinolone use seems to be the most important risk factor for CIPRO-R E. coli bacteremia.

Risk factors for nosocomial bacteremia due to methicillin-resistantStaphylococcus aureus

In a prospective surveillance study (February 1990–December 1991) performed at a 1000-bed teaching hospital to identify risk factors for nosocomial methicillin-resistantStaphylococcus aureus (MRSA) bacteremia, 309 patients were found to be colonized (n=103; 33 %) or infected (n=206; 67 %) by MRSA. Sixty-three of them developed bacteremia. Compared with 114 patients who had nosocomial bacteremia caused by methicillin-sensitiveStaphylococcus aureus during the same period of time, MRSA bacteremic patients had more severe underlying diseases (p<0.01), were more often in intensive care units (p<0.01) and had received prior antibiotic therapy more frequently (p<0.01). To further identify risk factors for MRSA bacteremia, univariate and multivariate analyses of this series of 309 patients were performed using the occurrence of MRSA bacteremia as the dependent variable. Among 14 variables analyzed, intravascular catheterization, defined as one or more intravascular catheters in place for more than 48 h, was the only variable selected by a logistic regression model as an independent risk factor (OR=2.7, CI=1.1–6.6). The results of this study reinforce the concept that recent antibiotic therapy may predispose patients to MRSA infection and suggest that among patients colonized or infected by MRSA, those with intravascular catheters are at high risk of developing MRSA bacteremia.

Risk factors for faecal carriage of Klebsiella pneumoniae producing extended spectrum β-lactamase (ESBL-KP) in the intensive care unit

In the course of an outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) in an intensive care unit (ICU), we conducted active surveillance to determine the risk factors for ESBL-KP faecal colonization of patients. We used weekly rectal samples during a four-month period. ESBL-KP was found in the faeces of 72 of 188 (38%) patients, and 42 (58%) of them were colonized within the first week of admission to the ICU. The probability of remaining free of faecal colonization was less than 20% at 30 days of ICU admission. The risk factors associated with ESBL-KP faecal colonization were clinical severity score at admission (P = 0.004), arterial catheterization (P = 0.002), total parenteral nutrition (P = 0.04), urinary catheterization (P = 0.01), mechanical ventilation (P < 0.001), and previous antibiotic therapy (P = 0.04). A logistic regression analysis identified duration of urinary catheterization (OR:3.5; 95% CI 1.2-10.3) and mechanical ventilation (OR:4.6; 95% CI 1.1-19.3) as independent risk factors for ESBL-KP faecal colonization. Our results suggest that in an ESBL-KP prevalent environment, manipulations that facilitate cross-infection are the most relevant in the acquisition of the micro-organism and risk increases throughout hospitalization.

Staphylococcus aureus nasal carriage as a marker for subsequent staphylococcal infections in intensive care unit patients

From January to December 1994, 752 consecutive patients admitted to intensive care units (ICU) for more than two days were studied prospectively forStaphylococcus aureus colonization and infection. Nasal swabs were obtained at admission and weekly during the ICU stay. At ICU admission 166 patients (22.1%) wereStaphylococcus aureus nasal carriers, while 586 were free of nasal colonization. Of the 166 nasal carriers, 163 harbored methicillin-sensitiveStaphylococcus aureus (MSSA) and three methicillinresistantStaphylococcus aureus (MRSA). During the ICU stay 24 of the 586 noncolonized patients became nasal carriers (11 MSSA and 13 MRSA), and one nasal carrier initially colonized by MSSA was recolonized by MRSA. Staphylococcal infections were documented in 51 (6.8%) of the total 752 patients. After 14 days of ICU stay, the probability of developing staphylococcal infections was significantly higher for those patients who were nasal carriers at ICU admission than for those found to be initially negative (relative risk 59.6, 95% Cl 20.37–184.32; p<0.0001). In patients with ICU-acquired nasal colonization, most infections were documented prior to or at the time of the detection of the nasal colonization; thus, in this group of patients nasal carriage showed a lower predictive value for subsequentStaphylococcus aureus infections than that described classically. Paired isolates of nasal colonizing and clinical strains were studied by pulsed-field gel electrophoresis (PFGE) andmecA polymorphism analysis in 30 patients; identity was demonstrated in all but two patients. The results suggest that, outside the setting of an outbreak of MRSA, the detection ofStaphylococcus aureus nasal carriers on admission may be particularly useful in identifying those patients who are at high risk for developing staphylococcal infections during their ICU stay.

Risk factors and prognosis of catheter-related bloodstream infection in critically ill patients: a multicenter study

ObjectiveTo assess the risk factors associated with CR-BSI development in critically ill patients with non-tunneled, non-cuffed central venous catheters (CVC) and the prognosis of the episodes of CR-BSI. Design and setting; prospective, observational, multicenter study in nine Spanish Hospitals.PatientsAll subjects admitted to the participating ICUs from October 2004 to June 2005 with a CVC.InterventionsNone.Measurement and resultsOverall, 1,366 patients were enrolled and 2,101 catheters were analyzed. Sixty-six episodes of CR-BSI were diagnosed. The incidence of CR-BSI was significantly higher in CVC compared with peripherically inserted central venous catheters (PICVC) without significant differences among the three locations of CVC. In the multivariate analysis, duration of catheterization and change over a guidewire were the independent variables associated with the development of CR-BSI whereas the use of a PICVC was a protective factor. Excluding PICVC, 1,598 conventional CVC were analyzed. In this subset, duration of catheterization, tracheostomy and change over a guidewire were independent risk factors for CR-BSI. A multivariate analysis of predictors for mortality among 66 patients with CRSI showed that early removal of the catheter was a protective factor and APACHE II score at the admission was a strong determinant of in-hospital mortality.ConclusionsPeripherically inserted central venous catheters is associated with a lower incidence of CR-BSI in critically ill patients. Exchange over a guidewire of CVC and duration of catheterization are strong contributors to CR-BSI. Our results reinforce the importance of early catheter removal in critically ill patients with CR-BSI.

Community-acquired methicillin-resistant Staphylococcus aureus infections: an emerging threat in Spain

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has not been recognised previously as a cause of MRSA infections in Spain. Nineteen patients carrying Panton-Valentine leukocidin (PVL)-positive MRSA were identified in a Barcelona hospital, of whom 15 were immigrants, mostly from South America. Twelve developed skin and soft-tissue infections. The associated isolates carried the PVL gene and staphylococcal chromosomal cassette (SCC)mecIV. A dominant clone belonging to sequence type (ST)8 and related to the USA300 clone was identified by pulsed-field gel electrophoresis. This clone is emerging in Spain, primarily among immigrants from South America, but dissemination to the native Spanish population could increase.

Prevalence of methicillin‐resistant Staphylococcus aureus and factors associated with colonization among residents in community long‐term‐care facilities in Spain

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains are no longer limited to acute-care hospitals but have now spread to other healthcare settings such as long-term-care facilities (LTCFs), in most of which they are endemic. In Europe, few studies have addressed the MRSA situation in LTCFs. A cross-sectional study to determine MRSA prevalence and factors associated with S. aureus carriage in community LTCF residents is reported here. Nasal and decubitus ulcer cultures were performed for residents of nine community LTCFs. Residents were classified as MRSA carriers, methicillin-susceptible S. aureus carriers and non-carriers. Overall, 1377 nasal swabs and 82 decubitus ulcer cultures were performed. MRSA was isolated from 15.5% and 59.0% of the former and latter, respectively. The prevalence of MRSA colonization was 16.8% (95% CI 14.9-18.8), varying from 6.7% to 35.8% (p <0.001) among LTCFs. Several independent variables were related to MRSA colonization. It is noteworthy that residents in an LTCF with fewer than 150 beds had at least a two-fold higher probability of being MRSA carriers. Modifiable factors were medical devices, decubitus ulcers and previous antibiotic treatment. An age of 85 years or older, a Charlson index >or=2 and transfer from an acute-care facility were non-modifiable factors also related to MRSA colonization. A high MRSA prevalence among residents in community LTCFs in Spain, with great variability among facilities, was found. The factors identified as being associated with MRSA colonization could be prevented by the implementation of several measures. Control strategies need to be coordinated between LTCFs and acute-care hospitals.

Infections due to Escherichia coli producing extended-spectrum β-lactamase among hospitalised patients: factors influencing mortality

We performed a retrospective matched-cohort study to determine the risk factors for mortality among patients with Escherichia coli infections. From January 1996 to December 2003, 100 hospitalised patients with extended-spectrum beta-lactamase (ESBL)-producing E. coli infections were compared with patients not infected with ESBL-producing E. coli. These patients were selected according to the same site of infection and the closest date of admission. Comparison of the two groups showed that empirical antibiotic therapy was more often inadequate in patients infected with ESBL-producing E. coli (44% vs 15%; P<0.01), and that early mortality (16% vs 6%; P=0.02) and overall mortality (25% vs 11%; P=0.01) were also significantly higher in patients with ESBL-producing E. coli infections. A multivariate model identified the urinary tract focus as the only independent risk factor influencing early mortality for E. coli infections [odds ratio (OR): 0.1; 95% confidence interval (CI): 0.03-0.7; P=0.01]. All 12 patients with ESBL-producing E. coli urinary tract infections treated initially with an oxyimino-beta-lactam survived. Subsequent analysis of the factors influencing early mortality in the cohort of 130 patients with a non-urinary E. coli infection found inadequate empirical antibiotic therapy as an independent risk factor for mortality only for non-urinary E. coli infections (adjusted OR: 3.0; 95% CI: 1.0-8.6; P=0.03). The study showed that hospitalised patients with ESBL-producing E. coli infections more often receive inadequate empiric antibiotic therapy and have a higher mortality rate than those infected with non-ESBL-producing strains. The site of infection strongly influences mortality. The administration of inadequate empirical antibiotic therapy is independently associated with higher mortality only among patients with non-urinary tract infections.

Documento de consenso sobre el tratamiento de la bacteriemia y la endocarditis causada por Staphylococcus aureus resistente a la meticilina

Bacteremia and endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA) are prevalent and clinically important. The rise in MRSA bacteremia and endocarditis is related with the increasing use of venous catheters and other vascular procedures. Glycopeptides have been the reference drugs for treating these infections. Unfortunately their activity is not completely satisfactory, particularly against MRSA strains with MICs > 1 microg/mL. The development of new antibiotics, such as linezolid and daptomycin, and the promise of future compounds (dalvabancin, ceftobiprole and telavancin) may change the expectatives in this field.The principal aim of this consensus document was to formulate several recommendations to improve the outcome of MRSA bacteremia and endocarditis, based on the latest reported scientific evidence. This document specifically analyzes the approach for three clinical situations: venous catheter-related bacteremia, persistent bacteremia, and infective endocarditis due to MRSA.