A consensus statement on empiric therapy for suspected gram-positive infections in surgical patients

BACKGROUND

Multidrug resistance among gram-positive pathogens in tertiary and other care centers is common. A systematic decision pathway to help select empiric antibiotic therapy for suspected gram-positive postsurgical infections is presented.

DATA SOURCES

A Medline search with regard to empiric antibiotic therapy was performed and assessed by the 15-member expert panel. Two separate panel meetings were convened and followed by a writing, editorial, and review process.

CONCLUSIONS

The main goal of empiric treatment in postsurgical patients with suspected gram-positive infections is to improve clinical status. Empiric therapy should be initiated at the earliest sign of infection in all critically ill patients. The choice of therapy should flow from beta-lactams to vancomycin to parenteral linezolid or quinupristin-dalfopristin. In patients likely to be discharged, oral linezolid is an option. Antibiotic resistance is an important issue, and in developing treatment algorithms for reduction of resistance, the utility of these new antibiotics may be extended and reduce morbidity and mortality.

Outcome of Staphylococcus aureus bacteremia in patients with eradicable foci versus noneradicable foci

To determine the outcome of Staphylococcus aureus bacteremia (SAB) on mortality, including the impact of methicillin resistance and an initial delay (< or =48 h) of appropriate antibiotics, a retrospective cohort study including 238 patients with SAB was performed. By logistic regression, noneradicable or noneradicated foci, underlying cirrhosis, and cancer were found to be independent predictors of mortality. In patients with eradicable foci, there were no significant differences in the associated mortality rate between methicillin-resistant SAB (11%) and methicillin-susceptible SAB (13%), and between inappropriate (13%) and appropriate (10%) empirical therapy, respectively (P=.79 and P=.78, respectively). By logistic regression, it was found that, in the subgroup of patients with noneradicable foci, underlying cirrhosis (odds ratio [OR], 3.1) and methicillin-resistant SAB (OR, 2.4) were independently associated with mortality.

Adverse clinical and economic outcomes attributable to methicillin resistance among patients with Staphylococcus aureus surgical site infection

Data for 479 patients were analyzed to assess the impact of methicillin resistance on the outcomes of patients with Staphylococcus aureus surgical site infections (SSIs). Patients infected with methicillin-resistant S. aureus (MRSA) had a greater 90-day mortality rate than did patients infected with methicillin-susceptible S. aureus (MSSA; adjusted odds ratio, 3.4; 95% confidence interval, 1.5-7.2). Patients infected with MRSA had a greater duration of hospitalization after infection (median additional days, 5; P<.001), although this was not significant on multivariate analysis (P=.11). Median hospital charges were 29,455 dollars for control subjects, 52,791 dollars for patients with MSSA SSI, and 92,363 dollars for patients with MRSA SSI (P<.001 for all group comparisons). Patients with MRSA SSI had a 1.19-fold increase in hospital charges (P=.03) and had mean attributable excess charges of 13,901 dollars per SSI compared with patients who had MSSA SSIs. Methicillin resistance is independently associated with increased mortality and hospital charges among patients with S. aureus SSI.

Comparison of mortality associated with methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteremia: a meta-analysis

A meta-analysis was performed to summarize the impact of methicillin-resistance on mortality in Staphylococcus aureus bacteremia. A search of the MEDLINE database for studies published during the period of 1 January 1980 through 31 December 2000 and a bibliographic review identified English-language studies of S. aureus bacteremia. Studies were included if they contained the numbers of and mortality rates for patients with methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) bacteremia. Data were extracted on demographic characteristics of the patients, adjustment for severity and comorbid illness, source of bacteremia, and crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for in-hospital mortality. When the results were pooled with a random-effects model, a significant increase in mortality associated with MRSA bacteremia was evident (OR, 1.93; 95% CI, 1.54-2.42; P<.001); significant heterogeneity was present. We explored the reasons for heterogeneity by means of subgroup analyses. MRSA bacteremia is associated with significantly higher mortality rate than is MSSA bacteremia.

Are all MRSA made equal?

The health and economic burden of methicillin-resistant Staphylococcus aureus (MRSA) in the medical realm is considerable. Although there is ample clinical and laboratory evidence indicating that methicillin-susceptible S. aureus (MSSA) is heterogeneous in disease causation, the same heterogeneity has not been well documented for MRSA. Data from animal models and human studies suggest that MRSA is at least as pathogenic as MSSA. Many comparative clinical studies, mainly retrospective, have assessed the virulence of MSSA and MRSA. Whereas the majority of these studies may be deficient in some aspects of clinical design, there has been a definite trend towards implicating MRSA as the more aggressive pathogen. Such an observation, however, must be tempered with the fact that few such studies have attempted to establish clonality among MRSA isolates. Thus, it is conceivable that hypervirulent clones may represent an important proportion of MRSA from hospital studies where patient-patient spread is likely and, accordingly, comparative studies may be biased. Future clinical studies should be prospective and should use well-defined and homogeneous patient groups. As well, for comparison of MRSA and MSSA, an understanding of clonality is essential.

Preventing vascular catheter-related infections: current controversies

Prevention of vascular catheter-related infection remains an important priority. This review focuses on salient controversies regarding optimal preventive methods. Intensity of surveillance for nosocomial infections was the single most important predictor of prevention in the Study of the Efficacy of Nosocomial Infection Control (SENIC). Used suboptimally by most hospitals in the SENIC study, surveillance is probably conducted even less today. There has been one randomized trial of the optimal method of aseptic insertion for central venous catheters and none comparing the 2 most frequently used sites. Scheduled replacement did not prevent infection in multiple randomized trials but, according to a recent survey, was still being used frequently. Chlorhexidine preparation of skin before and during catheterization has significantly reduced colonization of catheters in multiple randomized trials and should be used. Impregnation of catheter and/or hub surfaces with antiseptics raises less concern about fostering the development of antibiotic resistance than does the use of antibiotics for this purpose.

Systemic inflammatory response syndrome in adult patients with nosocomial bloodstream infection due to Staphylococcus aureus

To determine the impact of methicillin resistance on clinical course and outcome, we evaluated nosocomial bloodstream infections (BSIs) due to Staphylococcus aureus that were diagnosed in 82 adult patients at the Medical College of Virginia Hospitals from December 1995 through May 1997. Patients with BSI due to methicillin-resistant S. aureus were compared with patients with BSI due to methicillin-susceptible S. aureus; the groups did not differ with regard to inflammatory response or outcome. Mortality was predicted by systemic inflammatory response and Acute Physiology and Chronic Health Evaluation II score but did not correlate with bacterial resistance to methicillin.

Closed drainage using redon catheters for poststernotomy mediastinitis: results and risk factors for adverse outcome

BACKGROUND

Several different surgical techniques have been described for the treatment of poststernotomy mediastinitis. The present study was undertaken to evaluate the midterm results of primary closed drainage using Redon catheters and to identify risk factors for adverse outcome.

METHODS

Hospital records of 72 patients in whom poststernotomy mediastinitis developed and who underwent closed drainage with Redon catheters between April 1, 1996, and December 31, 1999, were reviewed. Follow-up was complete and averaged 11.8 +/- 11.5 months.

RESULTS

Of the 25 deaths (34.7%) recorded, 15 were directly attributable to mediastinitis. Actuarial estimates for freedom from mediastinitis-related death were 80.1% at 1 month and 77.4% at 1 year, 2 years, and 3 years. Logistic regression identified older age (odds ratio, 1.1; 95% confidence interval, 1.02 to 1.18), incubation time of 14 days or less (6.5; 1.33 to 31.4), and methicillin-resistant Staphylococcus aureus (5.8; 1.2 to 27.2) as independent risk factors for mediastinitis-related death. Reintervention for recurrent mediastinitis was necessary in 9 patients (12.5%) and occurred at a mean interval of 18.7 +/- 13.5 days from the first debridement. Actuarial estimates for freedom from reintervention were 87.1% at 1 month and 85.2% at 1 year, 2 years, and 3 years. The combined end point of treatment failure (mediastinitis-related death or reintervention) was recorded in 9 patients (26.4%). Actuarial estimates for freedom from treatment failure were 74.3% at 1 month and 72.7% at 1 year, 2 years, and 3 years. Logistic regression identified older age (1.01; 1.02 to 1.18), preoperative renal insufficiency (6.8; 1.04 to 44.5), and methicillin-resistant S aureus infection (4.8; 1.04 to 22.33) as independent risk factors for treatment failure (includes mediastinitis-related death and reintervention [with or without death]).

CONCLUSIONS

Primary closed drainage using Redon catheters is an effective and simple treatment for most patients in whom poststernotomy mediastinitis develops. However, patients with methicillin-resistant S aureus infection or recurrent mediastinitis may benefit from a more aggressive approach.

Methicillin-resistant Staphylococcus aureus in two tertiary-care centers in Jeddah, Saudi Arabia

OBJECTIVE

To review clinical experience with methicillin-resistant Staphylococcus aureus (MRSA) in tertiary-care hospitals in Jeddah, Saudi Arabia.

DESIGN

Retrospective review for the year 1998.

SETTING

Two tertiary-care hospitals.

METHODS

Results of MRSA-positive cultures of clinical specimens obtained as part of investigations for suspected infections were retrieved from the microbiology laboratories' records. Charts of patients were reviewed, with standardized data collection.

RESULTS

Of 673 S. aureus isolates identified, 222 (33%, or 6.8 isolates/1,000 admissions) were MRSA. Overall MRSA prevalence was 2% in 1988. Nosocomial acquisition occurred in 84.2% of cases. All age groups were affected, and 52% of patients had at least one comorbidity. MRSA prevalence was highest in the intensive care units (26.6% of all isolates), the medical wards (24.8%), and the surgical wards (19.8%). Seventy-three percent of isolates caused infection; the rest represented colonization. Surgical wounds (35.2%), the chest (29%), and central venous catheters (13%) were the most common sites of infection. Bacteremia occurred in 15.4% of patients. Local signs (84%) and fever (75.9%) were the most common clinical manifestations. Respiratory distress and septic shock occurred in 30.2% and 13.6% of cases, respectively. Of 162 patients with MRSA infection and 60 patients with MRSA colonization, 95.7% and 70% received antibiotics in the preceding 6 weeks, respectively (P<.0001). The total mortality of patients with MRSA infection was 53.7%: 36.4% as a result of MRSA infection and 17.3% as a result of other causes.

CONCLUSIONS

The prevalence of MRSA is high and rapidly increasing in the two hospitals, as it is worldwide. Control measures to prevent the spread of MRSA in hospitals should continue, with reinforcement of hygienic precautions and development of policies to restrict the use of antibiotics.

Poststernotomy mediastinitis due to Staphylococcus aureus: comparison of methicillin-resistant and methicillin-susceptible cases

The objective of the study was to compare the outcome of poststernotomy mediastinitis (PSM) caused by methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA, respectively). Hospital records of 41 patients with S. aureus PSM who were all treated by closed drainage from 1 April 1996 through 1 February 2000 were reviewed. PSM was caused by MRSA in 15 patients and by MSSA in 26. Follow-up (+/-SD) averaged 12.5+/-14.0 months per patient. Both groups had similar perioperative characteristics. Patients with MRSA PSM had a significantly lower actuarial survival rate than did patients with MSSA PSM (60.0%+/-12.6%, 52.5%+/-3.4%, and 26.3%+/-19.7% versus 84.6%+/-7.1%, 79.0%+/-8.6%, and 79.0%+/-8.65 at 1 month, and at 1 and 3 years, respectively; values are +/- SD; P=.04). PSM-related death and treatment failure were significantly higher in the MRSA group than in the MSSA group (P=.03 and.02, respectively). Logistic regression analysis revealed that MRSA was the only independent risk factor for overall mortality. In conclusion, the clinical outcome of PSM caused by MRSA is poorer than that caused by MSSA.

Hospital-acquired pneumonia: risk factors, microbiology, and treatment

Pneumonia complicates hospitalization in 0.5 to 2.0% of patients and is associated with considerable morbidity and mortality. Risk factors for hospital-acquired pneumonia (HAP) include mechanical ventilation for > 48 h, residence in an ICU, duration of ICU or hospital stay, severity of underlying illness, and presence of comorbidities. Pseudomonas aeruginosa, Staphylococcus aureus, and Enterobacter are the most common causes of HAP. Nearly half of HAP cases are polymicrobial. In patients receiving mechanical ventilation, P aeruginosa, Acinetobacter, methicillin-resistant S aureus, and other antibiotic-resistant bacteria assume increasing importance. Optimal therapy for HAP should take into account severity of illness, demographics, specific pathogens involved, and risk factors for antimicrobial resistance. When P aeruginosa is implicated, monotherapy, even with broad-spectrum antibiotics, is associated with rapid evolution of resistance and a high rate of clinical failures. For pseudomonal HAP, we advise combination therapy with an antipseudomonal beta-lactam plus an aminoglycoside or a fluoroquinolone (eg, ciprofloxacin).

Molecular epidemiology of methicillin resistant Staphylococcus aureus isolated from newborns in a hospital in Rio de Janeiro, Brazil

Methicillin resistant Staphylococcus aureus (MRSA) is an organism that is frequently transmitted in hospitals and perinatal units. The MRSA is considered a public health problem in neonatology because of its strong potential for dissemination in the wards associated with high rates of morbidity and mortality. In this study we describe the bacteriological, epidemiological and molecular characteristics of MRSA isolated from anterior nares and blood cultures of newborns hospitalized in a public maternity hospital in the city of Rio de Janeiro, Brazil. The frequency of MRSA isolated from nasal swabs of newborns was 47.8% (43/90). The genetic analysis of MRSA strains from anterior nares, showed 8 different pulsed field gel electrophoresis patterns (PFGE). Upon analysis of PFGE patterns of the 12 MRSA strains isolated from blood cultures, 8 different patterns were observed, 9 (75%) strains were genetic related to nasal secretion isolates patterns. In conclusion, our data demonstrate the importance of screening of newborns for the presence of MRSA in Brazilian hospitals and the usefulness of genetic typing of these pathogen during epidemiologic studies. This should lead to a better knowledge on the significancy and spreading of MRSA in the hospitals.

Nosocomial methicillin-resistant Staphylococcus aureus bacteremia: is it any worse than nosocomial methicillin-sensitive Staphylococcus aureus bacteremia?

OBJECTIVE

To determine the comparative virulence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S aureus (MSSA) by consideration of predisposing factors and outcomes in patients infected with these organisms in the healthcare setting.

DESIGN

Analysis of an historical cohort of 504 bacteremic patients (316 MSSA and 188 MRSA), examining factors associated with mortality.

SETTING

A 916-bed, university-affiliated, tertiary referral hospital.

RESULTS

Risk factors for the development of MRSA include male gender, admission due to trauma, immunosuppression, presence of a central vascular line or an indwelling urinary catheter, and a past history of MRSA infection. Overall mortality was 22%. Death due to bacteremia was significantly greater in the MRSA group (risk ratio, 1.68; P<.05), although these patients were not found to be more likely to die due to underlying disease during treatment of bacteremia. In those patients who recovered from bacteremia, no significant differences for the outcome of death could be determined between the MRSA and MSSA groups.

CONCLUSIONS

There is a general consensus in the published literature that MRSA bacteremia is more likely to be associated with death, and we confirm this conclusion. However, in contrast to other studies, our MRSA cohort does not appear to be more at risk of death due to underlying disease during treatment for bacteremia. Similarly, the general consensus that MRSA patients have an increased overall mortality was not confirmed in our study. Differences in comorbidities of patients may provide some explanation of these conflicting results, while an alternate explanation is that MRSA strains are more virulent than MSSA in some centers. Perhaps the most plausible explanation is that treatment is provided earlier and in a more aggressive fashion in some centers, leading to an overall lower mortality rate in all staphylococcal bacteremias in these institutions.

Inadequate antimicrobial treatment: an important determinant of outcome for hospitalized patients

Inadequate antimicrobial treatment, generally defined as microbiological documentation of an infection that is not being effectively treated, is an important factor in the emergence of infections due to antibiotic-resistant bacteria. Factors that contribute to inadequate antimicrobial treatment of hospitalized patients include prior antibiotic exposure, use of broad-spectrum antibiotics, prolonged length of stay, prolonged mechanical ventilation, and presence of invasive devices. Strategies to minimize inadequate treatment include consulting an infectious disease specialist, using antibiotic practice guidelines, and identifying quicker methods of microbiological identification. In addition, clinicians should determine the prevailing pathogens that account for the community-acquired and nosocomial infections identified in their hospitals. Clinicians can improve antimicrobial treatment by using empirical combination antibiotic therapy based on individual patient characteristics and the predominant bacterial flora and their antibiotic susceptibility profiles. This broad-spectrum therapy can then be narrowed when initial culture results are received. Further study evaluating the use of antibiotic practice guidelines and strategies to reduce inadequate treatment is necessary to determine their impact on patient outcomes.

Reasons for noncompliance with infection control guidelines

Concern frequently is voiced about individuals not complying with guidelines intended to prevent spread of antibiotic-resistant pathogens from patient to patient, but institutional decisions to ignore Centers for Disease Control and Prevention guidelines recommending detection and isolation of colonized patients also have contributed greatly to the increasing rate of infections due to these pathogens. This is so because colonized patients are the main reservoir for spread, and barrier precautions prevent spread much more effectively than Standard Precautions. Providing effective leadership and changing this culture of noncompliance must begin with the infection control team believing that spread is both important and preventable.

Cost of antimicrobial treatment for nosocomial infections based on a French prevalence survey

An estimate of the antibiotic cost of nosocomial infections (NI) was made in a university hospital group based on data collected in adult inpatients enrolled in the French national prevalence survey in 1996. Among the 6839 study patients, 636 (9.3%) presented with at least one NI, of these, data on antimicrobial treatment were available for 480. The overall daily antibiotic cost was estimated between FF 49,439 and 103,526, resulting in FF 103 to 216 per infected patient. The most expensive antibiotic treatment was prescribed in intensive care patients, for pneumonia for device-related NI, or for multi-resistant bacterial infections. Non-documented NI represented about 20% of the overall antibiotic cost. Beta-lactam antibiotics, especially third generation cephalosporins, and parenteral fluoroquinolones were the most expensive antimicrobial drugs. The cost of antibiotic treatment for NI represents a significant part of hospital expenditure that should be reduced by better control of highly expensive prescriptions.

Determinants of mortality in oncology patients colonized or infected with Staphylococcus aureus

Oxacillin-resistant Staphylococcus aureus (ORSA) infection is an important cause of hospital morbidity and mortality. The objective of this study was to identify the main factors associated with death in patients colonized or infected with Staphylococcus aureus in a cancer center. A matched-pair case-control study enrolled all patients infected or colonized with ORSA (cases) admitted to the Hospital do Câncer in Rio de Janeiro from 01/01/1992 to 12/31/1994. A control was defined as a patient hospitalized during the same period as the case-patients and colonized or infected with oxacillin-susceptible Staphylococcus aureus (OSSA). The study enrolled 95 cases and 95 controls. Patient distribution was similar for the two groups (p > or = 0.05) with respect to gender, underlying diseases, hospital transfer, prior infection, age, temperature, heart and respiratory rates, neutrophil count, and duration of hospitalization. Univariate analysis of putative risk factors associated with mortality showed the following significant variables: admission to the intensive care unit (ICU), presence of bacteremia, use of central venous catheter (CVC), ORSA colonization or infection, pneumonia, use of urinary catheter, primary lung infection, prior use of antibiotics, mucositis, and absence of cutaneous abscesses. Multivariate analysis showed a strong association between mortality and the following independent variables: admission to ICU (OR [odds ratio] = 7.2), presence of Staphylococcus bacteremia (OR = 6.8), presence of CVC (OR = 5.3), and isolation of ORSA (OR = 2.7). The study suggests a higher virulence of ORSA in comparison to OSSA in cancer patients.