Bacteremic complications of intravascular catheter tip colonization with Gram-negative micro-organisms in patients without preceding bacteremia

Although Gram-negative micro-organisms are frequently associated with catheter-related bloodstream infections, the prognostic value and clinical implication of a positive catheter tip culture with Gram-negative micro-organisms without preceding bacteremia remains unclear. We determined the outcomes of patients with intravascular catheters colonized with these micro-organisms, without preceding positive blood cultures, and identified risk factors for the development of subsequent Gram-negative bacteremia. All patients with positive intravascular catheter tip cultures with Gram-negative micro-organisms at the University Medical Center, Utrecht, The Netherlands, between 2005 and 2009, were retrospectively studied. Patients with Gram-negative bacteremia within 48 h before catheter removal were excluded. The main outcome measure was bacteremia with Gram-negative micro-organisms. Other endpoints were length of the hospital stay, in-hospital mortality, secondary complications of Gram-negative bacteremia, and duration of intensive care admission. A total of 280 catheters from 248 patients were colonized with Gram-negative micro-organisms. Sixty-seven cases were excluded because of preceding positive blood cultures, leaving 213 catheter tips from 181 patients for analysis. In 40 (19%) cases, subsequent Gram-negative bacteremia developed. In multivariate analysis, arterial catheters were independently associated with subsequent Gram-negative bacteremia (odds ratio [OR] = 5.00, 95% confidence interval [CI]: 1.20–20.92), as was selective decontamination of the digestive tract (SDD) (OR = 2.47, 95% CI: 1.07–5.69). Gram-negative bacteremia in patients who received SDD was predominantly caused by cefotaxime (part of the SDD)-resistant organisms. Mortality was significantly higher in the group with subsequent Gram-negative bacteremia (35% versus 20%, OR = 2.12, 95% CI: 1.00–4.49). Patients with a catheter tip colonized with Gram-negative micro-organisms had a high chance of subsequent Gram-negative bacteremia from any cause. This may be clinically relevant, as starting antibiotic treatment pre-emptively in high-risk patients with Gram-negative micro-organisms cultured from arterial intravenous catheters may be beneficial.     

Prognostic Factors Influencing Mortality in Cancer Patients with Neutropenia and Bacteremia

 The purpose of this study was to identify risk factors for mortality in neutropenic patients with cancer and bacteremia. A consecutive sample of 438 neutropenic patients (granulocyte count <0.5×10⁹/l) with cancer and bacteremia was studied to identify the clinical characteristics associated with mortality at the onset of bacteremia. The mean age of the subjects was 48 years (range, 15–87 years). Most cases of bacteremia (77%) were hospital-acquired and occurred in patients with acute leukemia (48%). Gram-positive organisms caused 233 (53%) episodes of bacteremia, gram-negative organisms caused 151 (34%) episodes, and 48 (11%) episodes were polymicrobial. The overall mortality within 30 days of the onset of bacteremia was 24.4%. The variables found to be independently associated with increased mortality using logistic regression techniques were as follows: shock at the onset of bacteremia (OR, 10; 95% CI, 4.2–23.8), pneumonia (OR,4.4; 95% CI, 1.9–10), uncontrolled cancer (OR,4.3; 95 %CI, 1.5–12.7), and absence of prophylaxis with norfloxacin (OR,2.4; 95%CI, 1.3–4.5). The prognostic factors ascertained in this study may help to identify those patients at higher risk of death. Medical intervention addressing some of these factors may improve the outcome of bacteremia in neutropenic patients with cancer.     

Pseudomonas aeruginosa Bacteremia in Patients Infected with Human Immunodeficiency Virus Type 1

 A prospective analysis of 43 episodes of Pseudomonas aeruginosa bacteremia in HIV-1-infected subjects was performed and the results compared with the incidence and outcome of Pseudomonas aeruginosa bacteremia in other high-risk patients, such as transplant recipients, leukemia patients, or patients hospitalized in the intensive care unit. The incidence of bacteremia/fungemia as a whole and of gram-negative and Pseudomonas aeruginosa bacteremia in particular was greater in HIV-1-infected subjects than in the unselected general population admitted. In contrast, the incidence of Pseudomonas aeruginosa bacteremia in HIV-1-infected patients did not differ from that in patients with other high-risk conditions. In patients with HIV-1 infection, independent risk factors for presenting Pseudomonas aeruginosa bacteremia were nosocomial origin (OR, 2.7; 95% CI, 1.3–5.7), neutropenia (OR, 2.7; 95% CI, 1.07–6.8), previous treatment with cephalosporins (OR, 3.6; 95% CI, 1.1–11.6), and a CD4+ cell count lower than 50 cells/mm³ (OR, 3.1; 95% CI, 1.7–8.6). Primary bacteremia and pneumonia were the most common forms of presentation. Fourteen (33%) patients died as a consequence of the bacteremia. The presence of severe sepsis (OR, 17.5; 95% CI, 3.2–68) and the institution of inappropriate definitive antibiotic therapy (OR, 2.7; 95% CI, 1.1–13) were independently associated with a poor outcome. One year after the development of bacteremia, only eight (19%) patients remained alive.     

Clinical features,antimicrobial susceptibilities,and outcomes of <Emphasis Type="Italic">Elizabethkingia meningoseptica</Emphasis> (<Emphasis Type="Italic">Chryseobacterium meningosepticum</Emphasis>) bacteremia at a medical center in Taiwan, 1999–2006

A total of 118 patients with Elizabethkingia meningoseptica bacteremia at a medical center in Taiwan from 1999 to 2006 were studied. Minimum inhibitory concentrations (MICs) of 99 preserved isolates were determined. The incidence (per 100,000 admissions) of E. meningoseptica bacteremia increased from 7.5 in 1996 to 35.6 in 2006 (p = 0.006). Among them, 84% presented with fever, 86% had nosocomial infections, and 60% had acquired the infection in intensive care units (ICUs). The most common underlying diseases were malignancy (36%) and diabetes mellitus (25%). Seventy-eight percent of patients had primary bacteremia, followed by pneumonia (9%), soft tissue infection, and catheter-related bacteremia (6%). Forty-five patients (38%) had polymicrobial bacteremia. Overall, the 14-day mortality was 23.4%. Multivariate analysis revealed E. meningoseptica bacteremia acquired in an ICU (p = 0.048, odds ratio [OR] 4.23) and presence of effective antibiotic treatment after the availability of culture results (p = 0.049, OR 0.31) were independent predictors of 14-day mortality. The 14-day mortality was higher among patients receiving carbapenems (p = 0.046) than fluoroquinolones or other antimicrobial agents. More than 80% of the isolates tested were susceptible to trimethoprim-sulfamethoxzole, moxifloxacin, and levofloxacin. The MIC₅₀ and MIC₉₀ of the isolates to tigecycline and doxycycline were both 4 μg/mL and 8 μg/ml, respectively.     

Inappropriate initial antimicrobial therapy as a risk factor for mortality in patients with community-onset <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> bacteraemia

This study was performed to identify the risk factors for mortality and evaluate the effect of inappropriate initial antimicrobial therapy on the outcomes of patients with community-onset Pseudomonas aeruginosa bacteraemia in an emergency department (ER) setting. All cases with P. aeruginosa bacteraemia occurring within 48 h after ER visit from January 2000 to December 2005 were retrospectively analysed. A total of 106 community-onset P. aeruginosa bacteraemia cases in the ER were included (mean age, 57.61 ± 14.44 years old; M:F, 58:48). Although P. aeruginosa bacteraemia was diagnosed in the ER, most of the cases of P. aeruginosa bacteraemia were healthcare-associated (88.7%). Malignancy (n = 83, 78.3%) was the most common underlying disorder. Fifty patients (47.2%) were neutropaenic and 56 patients (52.8%) had septic shock. The overall 30-day mortality rate was 26.4% (28/106). In the univariate analysis, underlying malignancy, high Charlson’s weighted index of comorbidity (≥3), high Pitt bacteraemia score (≥4), indwelling central venous catheter and inappropriate initial therapy were significantly associated with 30-day mortality (all P < 0.05). In the multivariate analysis, high Pitt bacteraemia score (OR, 17.03; 95% CI, 4.60–63.15; P < 0.001) and inappropriate initial antimicrobial therapy (OR, 4.29; 95% CI, 1.39–13.24; P = 0.011) were found to be significant risk factors for 30-day mortality. The 30-day mortality rate was significantly higher in the inappropriate therapy group (18/51, 35.3%) than in the appropriate therapy group (10/55, 18.2%) (P = 0.046). This study demonstrated that inappropriate initial antimicrobial therapy was significantly associated with unfavourable outcomes in patients with community-onset P. aeruginosa bacteraemia. As P. aeruginosa bacteraemia can be a fatal infection, even when community-onset, inappropriate antimicrobial therapy should be avoided in suspected cases of P. aeruginosa bacteraemia. This study was presented in part at the 44th Annual Meeting of the Infectious Diseases Society of America (IDSA), 12–15 October 2006 held at the Metro Toronto Convention Centre in Toronto, Canada (abstract no. 1410)     

Elevated soluble urokinase plasminogen activator receptor (suPAR) predicts mortality in Staphylococcus aureus bacteremia

The soluble form of urokinase-type plasminogen activator receptor (suPAR) is a new inflammatory marker. High suPAR levels have been shown to associate with mortality in cancer and in chronic infections like HIV and tuberculosis, but reports on the role of suPAR in acute bacteremic infections are scarce. To elucidate the role of suPAR in a common bacteremic infection, the serum suPAR levels in 59 patients with Staphylococcus aureus bacteremia (SAB) were measured using the suPARnostic™ ELISA assay and associations to 1-month mortality and with deep infection focus were analyzed. On day three, after the first positive blood culture for S. aureus, suPAR levels were higher in 19 fatalities (median 12.3; range 5.7–64.6 ng/mL) than in 40 survivors (median 8.4; range 3.7–17.6 ng/mL, p = 0.002). This difference persisted for 10 days. The presence of deep infection focus was not associated with elevated suPAR levels as compared to patients with no deep infection focus. suPAR was found to be prognostic for mortality in receiver operator characteristic (ROC) curve analysis, which was not observed for serum C-reactive protein (CRP); the area under the curve (AUC) for suPAR was 0.754 (95% confidence interval [CI], 0.615–0.894, p = 0.003) and for CRP, it was 0.596 (95% CI, 0.442–0.750, p = 0.253). The optimal suPAR cut-off value in predicting 1-month mortality was 9.25 ng/mL. In conclusion, our study demonstrates that the new promising biomarker, serum suPAR concentration, was able to predict mortality in SAB.     

Impact of healthcare-associated acquisition on community-onset Gram-negative bloodstream infection: a population-based study

We performed a population-based study to examine the influence of healthcare-associated acquisition on pathogen distribution, antimicrobial resistance, short- and long-term mortality of community-onset Gram-negative bloodstream infections (BSI). We identified 733 unique patients with community-onset Gram-negative BSI (306 healthcare-associated and 427 community-acquired) among Olmsted County, Minnesota, residents from 1 January 1998 to 31 December 2007. Multivariate logistic regression was used to examine the association between healthcare-associated acquisition and microbiological etiology and antimicrobial resistance. Multivariate Cox proportional hazards regression was used to evaluate the influence of the site of acquisition on mortality. Healthcare-associated acquisition was predictive of Pseudomonas aeruginosa (odds ratio [OR] 3.14, 95% confidence intervals [CI]: 1.59–6.57) and the group of Enterobacter, Citrobacter, and Serratia species (OR 2.23, 95% CI: 1.21–4.21) as causative pathogens of community-onset Gram-negative BSI. Healthcare-associated acquisition was also predictive of fluoroquinolone resistance among community-onset Gram-negative bloodstream isolates (OR 2.27, 95% CI: 1.18–4.53). Healthcare-associated acquisition of BSI was independently associated with higher 28-day (hazard ratio [HR] 3.73, 95% CI: 2.13–6.93) and 1-year mortality (HR 3.60, 95% CI: 2.57–5.15). Because of differences in pathogen distribution, antimicrobial resistance, and outcomes between healthcare-associated and community-acquired Gram-negative BSI, identification of patients with healthcare-associated acquisition of BSI is essential to optimize empiric antimicrobial therapy.     

Predictors of mortality in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia: the role of empiric antibiotic therapy

The objective of this study was to evaluate prognostic factors and the influence of different empiric antibiotic therapies on outcome and mortality in a cohort of 100 inpatients with bacteraemia (84 cases nosocomial) caused by methicillin-resistant Staphylococcus aureus (MRSA). Patients were investigated by means of a standard protocol at a 944-bed hospital in the years 2000–2004. Empiric antibiotic therapies included vancomycin (n = 49), teicoplanin (n = 20), linezolid (n = 17), other antibiotics active in vitro (n = 7), and inactive antibiotics (n = 7). Overall mortality was 40% (12% among linezolid-treated patients; 46.3% among glycopeptide-treated patients). In bivariate analyses, the following factors were statistically associated with higher mortality: rapidly fatal underlying disease, altered mental status, metabolic acidosis, and acute severe clinical condition at the onset of bacteraemia; development of complications (septic shock, renal failure, and disseminated intravascular coagulopathy); empiric monotherapy with glycopeptides (vs combination therapy with an aminoglycoside); and inadequate empiric treatment. Empiric therapy with linezolid was associated with lower mortality. In multivariate analysis, risk factors associated with higher mortality included acute severity of illness (OR 7.49; 95%CI 1.19–25.3) and altered mental status (OR 4.83; 95%CI 1.22–19.15) at onset, complications (OR 3.42; 95%CI 1.02–17.46), and inappropriate empiric treatment (OR 7.6; 95%CI 1.87–31.14). In multivariate analysis limited to patients who received empiric therapy with either linezolid (n = 17) or glycopeptides (n = 69), linezolid was associated with greater rates of survival (OR 7.7; 95%CI 1.1–53) and microbiological eradication (OR 11.76; 95%CI 1.46–90.9) but not with fewer complications (OR 0.71; 95%CI 0.16–3.25). In conclusion, the main prognostic factors associated with mortality in patients with MRSA bacteraemia are complications, acute severe clinical condition at onset, and inappropriate empiric treatment. Empiric therapy with linezolid was associated with greater survival and more successful microbiological eradication but did not reduce complications.     

Influence of tracheostomy on the incidence of central venous catheter-related bacteremia

Although there are many studies on catheter-related infection, there are scarce data about the influence of tracheostomy in the incidence of central venous catheter-related bacteremia (CRB). In this cohort study, we found a higher incidence of CRB in patients with tracheostomy than without (11.25 vs. 1.43 per 1,000 catheter-days; odds ratio [OR] = 7.99; 95% confidence interval [CI] = 4.38–infinite; P < 0.001). Besides, we found a higher incidence of CRB in patients with tracheostomy using the jugular access compared to subclavian access (21.64 vs. 5.11 per 1,000 catheter-days; OR = 4.23; 95% CI = 1.44–infinite; P = 0.0097).     

Bloodstream infections among human immunodeficiency virus-infected adult patients: epidemiology and risk factors for mortality

This study was undertaken to describe the epidemiology and sensitivity pattern of pathogens causing community-acquired (CA) and nosocomial (N) bloodstream infection (BSI) in adult HIV-infected patients and to establish risk factors for mortality. The type of study was a retrospective analysis of BSI episodes prospectively collected through a blood culture surveillance program from January 1991 to December 2006. We used non-conditional logistic regression methods with death as a dependent variable. One thousand and seventy-seven episodes of BSI (6%) occurred in HIV-infected patients out of 16,946 episodes during the period of study. CA and N BSI were 634 (59%) and 443 (41%) respectively. S. pneumoniae and S. aureus were the most frequent pathogens (n = 279, 44%) in CA BSI. Coagulase-negative staphylococci and S. aureus were the most frequent micro-organisms isolated in N cases (n = 169, 38%). Cotrimoxazole resistance was common in CA and N BSI and was caused by gram-negative bacilli (50% and 61% respectively). However, resistance rates to ceftriaxone were low (3%). Crude mortality accounted for 140 cases (13%). The independent risk factors associated with mortality were: liver cirrhosis (OR: 2.90, p = 0.001), corticosteroids treatment (OR: 3.51, p < 0.001), neutropenia (OR: 2.21, p = 0.02), inappropriate empirical therapy (OR: 2.44, p = 0.006), and isolate of C. albicans (OR: 7.58, p = 0.010). BSI in adult HIV-infected patients was often caused by gram-positive pathogens in both CA and N settings. Inappropriate empirical therapy and the presence of other immunosuppressive factors were independent risk factors for mortality. Ceftriaxone could be used as the initial empiric therapy for HIV-infected patients with suspected CA BSI. This study was partially presented at the 18th European Congress of Clinical Microbiology and Infectious Diseases (Barcelona, April 2008).     

Statins are associated with improved outcomes of bloodstream infection in solid-organ transplant recipients

Among recipients of intra-abdominal solid-organ transplants, bloodstream infections (BSIs) are a major cause of mortality. We undertook a retrospective cohort study of recipients of kidney, pancreas, and/or liver transplants with BSIs at a single center over an 11-year period. Multivariate analysis using logistic regression was used to determine independent predictors of 15-day mortality and clinical cure, with a focus on the use of statins. Three hundred and eleven recipients of solid-organ transplants had 604 episodes of BSI. Forty-four (14%) died within 15 days of BSI. Sixteen percent did not achieve clinical cure. In the multivariate model, each one point increase in the APACHE score was associated with a 1.09-fold increased risk of death (95% confidence interval [CI] 1.00–1.18, P = 0.03). The lack of appropriate antibiotic therapy was associated with a four-fold higher risk of death within 15 days (odds ratio [OR] 4.65, 95% CI 1.46–14.78, P = 0.009). Statin use was protective (OR 0.18, 95% CI 0.04–0.78). Patients with high APACHE scores, nosocomial rather than community source of BSI, lack of appropriate antibiotic therapy, and mental status changes were less likely to achieve clinical cure of their BSIs. In conclusion, appropriate antibiotic therapy and statin use are associated with lower risk of mortality from BSIs in this patient population.     

Predictive scoring model of mortality in Gram-negative bloodstream infection

Mortality is a well-recognized complication of Gram-negative bloodstream infection (BSI). The aim of this study was to develop a model to predict mortality in patients with Gram-negative BSI by using the Pitt bacteraemia score (PBS) and other clinical and laboratory variables. A cohort of 683 unique adult patients who were followed for at least 28 days after admission to Mayo Clinic Hospitals with Gram-negative BSI from 1 January 2001 to 31 October 2006 and who received clinically predefined appropriate empirical antimicrobial therapy was retrospectively identified. Multivariable logistic regression was used to identify independent risk factors for 28-day all-cause mortality. Regression coefficients from a multivariable model were used to develop a risk score to predict mortality following Gram-negative BSI. Malignancy (OR 3.48, 95% CI 1.94–6.22), liver cirrhosis (OR 5.42, 95% CI 2.52–11.65), source of BSI other than urinary tract or central venous catheter infection (OR 5.54, 95% CI 2.42–12.69), and PBS (OR 1.98, 95% CI 0.92–4.25 for PBS of 2–3 and OR 6.42, 95% CI 3.11–13.24 for PBS ≥ 4) were identified as independent risk factors for 28-day mortality in patients with Gram-negative BSI. A risk-score model was created by adding points for each independent risk factor, and had a c-statistic of 0.84. Patients with risk scores of 0, 4, 8, 12 and 16 had estimated 28-day mortality rates of approximately 0%, 3%, 14%, 45%, and 81%, respectively. The Gram-negative BSI risk score described herein estimated mortality risk with high discrimination in patients with Gram-negative BSI who received clinically adequate empirical antimicrobial therapy.     

Fungal colonization and/or infection in non-neutropenic critically ill patients: results of the EPCAN observational study

The purpose of this paper is to determine the incidence of fungal colonization and infection in non-neutropenic critically ill patients and to identify factors favoring infection by Candida spp. A total of 1,655 consecutive patients (>18 years of age) admitted for ≥7 days to 73 medical-surgical Spanish intensive care units (ICUs) participated in an observational prospective cohort study. Surveillance samples were obtained once a week. One or more fungi were isolated in different samples in 59.2% of patients, 94.2% of which were Candida spp. There were 864 (52.2%) patients with Candida spp. colonization and 92 (5.5%) with proven Candida infection. In the logistic regression analysis risk factors independently associated with Candida spp. infection were sepsis (odds ratio [OR] = 8.29, 95% confidence interval [CI] 5.07–13.6), multifocal colonization (OR = 3.49, 95% CI 1.74–7.00), surgery (OR = 2.04, 95% CI 1.27–3.30), and the use of total parenteral nutrition (OR = 4.37, 95% CI 2.16–8.33). Patients with Candida spp. infection showed significantly higher in-hospital and intra-ICU mortality rates than those colonized or non-colonized non-infected (P < 0.001). Fungal colonization, mainly due to Candida spp., was documented in nearly 60% of non-neutropenic critically ill patients admitted to the ICU for more than 7 days. Proven candidal infection was diagnosed in 5.5% of cases. Risk factors independently associated with Candida spp. infection were sepsis, multifocal colonization, surgery, and the use of total parenteral nutrition.     

Infectious endocarditis in patients with cirrhosis of the liver: a model of infection in the frail patient

The purposes of this paper was to discover whether cirrhosis is a predisposing cause of infectious endocarditis (IE) and to determine the microbiology, prognosis and the role of cardiac surgery on mortality. A review of cases of IE at a university-affiliated hospital over a period of 10 years was conducted. Thirty-one (9.8%) patients among 316 cases of IE had hepatic cirrhosis. Valve disorders were present in 62.2% of cirrhotic patients and infection occurred on the aortic (48%) and mitral valves (45%). Endocarditis was hospital-acquired in 14 (45%) and 11 (17.7%) cirrhotic patients and controls, respectively (odds ratio [OR] 3.82; 95% confidence interval [CI]: 1.46–9.99; p = 0.005). Staphylococcus aureus was the most common causative microorganism, but β-hemolytic streptococci were most frequently isolated in cirrhotic patients (OR 8.75; 95% CI: 1.7–45.2; p = 0.001). Renal failure was more frequent in patients with cirrhosis (OR 8.23; 95% CI: 3.06–22.2; p = 0.001). Cirrhotic patients had a higher mortality (51% vs. 17.7%; OR 4.95; 95% CI: 1.89–12.91; p = 0.001) associated with the severity of liver disease. Valve replacement was performed less frequently in cirrhotic patients (56.2% vs. 92%) and the operative mortality was extremely high in patients at stages B and C. Hepatic cirrhosis is a frequent comorbid condition in patients with endocarditis. Due to the presence of severe hepatic dysfunction, cardiac surgery is not undertaken even when indicated and mortality is high in stages B and C. Endocarditis is a serious hazard for hospitalized cirrhotic patients.     

Risk factors for mortality among patients with Stenotrophomonas maltophilia bacteremia in Tokyo, Japan, 1996–2009

Stenotrophomonas maltophilia is an important nosocomial pathogen, especially among immunocompromised patients. The objective of this study was to clarify the clinical characteristics, prognosis, and prognostic factors of patients with S. maltophilia bacteremia in Japan. The microbiology records of all patients with S. maltophilia bacteremia between January 1996 and April 2009 at Toranomon Hospital, Tokyo, Japan, were retrospectively reviewed. A total of 53 cases of bacteremia were identified. Thirty patients had an underlying hematological disorder, and 23 were receiving hematopoietic transplantation. The overall mortality rate was 51%. On univariate analysis, neutropenia (p < 0.01), the presence of a central venous catheter, and mixed infection with enterococci (p < 0.05) were significantly related to the mortality. Among these variables, neutropenia (p < 0.01) and mixed infection with enterococci (p < 0.05) were independent factors associated with mortality. In contrast, all eight patients in whom S. maltophilia was the etiologic agent of catheter-related infection survived following catheter removal. S. maltophilia is an important pathogen among immunocompromised patients, especially in the neutropenic phase or mixed infection with enterococci. If a central venous catheter was present at the onset of S. maltophilia bacteremia, the prompt removal of the catheter was important.     

Bacteremia caused by <Emphasis Type="Italic">Brevundimonas</Emphasis> species at a tertiary care hospital in Taiwan, 2000–2010

We investigated clinical and microbiological characteristics of 30 patients with Brevundimonas bacteremia treated at a tertiary care hospital in Taiwan during 2000–2010. All the 30 bacteria isolates were confirmed to the species level by 16S rRNA sequencing analysis. Minimum inhibitory concentrations (MICs) of 11 antimicrobial agents against these isolates were determined by the agar dilution method. Seventeen (57%) patients had underlying malignancy, 12 (40%) had undergone central catheter placement, and 13 (43%) had received chemotherapy within the previous three months. Eight (27%) patients had community-acquired bacteremia and the remaining 22 patients (73%) had healthcare-associated bacteremia. The overall 14-day and 30-day mortality rates were 13% and 17%, respectively. Among the 30 isolates, B. vesicularis constituted most commonly (n = 22, 63%), followed by B. nasdae (n = 5) and B. diminuta (n = 3). All isolates were susceptible to piperacillin-tazobactam and amikacin, while all were resistant to ciprofloxacin and colistin. Tigecycline (MICs at which 90% of isolates are inhibited [MIC₉₀] was 0.12 mg/L) and doripenem (MIC₉₀ of 1 mg/L) both possessed good in vitro activities. In conclusions, Brevundimonas should be considered a pathogen that can cause bacteremia in immunocompromised hosts. Piperacillin-tazobactam, amikacin, doripenem, and tigecycline exhibit good in vitro activities against these ciprofloxacin- and colistin-resistant Brevundimonas species.     

Appropriate non-carbapenems are not inferior to carbapenems as initial empirical therapy for bacteremia caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a propensity score weighted multicenter cohort study

The efficacy of empirical non-carbapenem antibiotics for extended-spectrum beta-lactamase-producing Enterobacteriaceae bacteremia (ESBL-B) is still inconclusive. We conducted a multicenter retrospective cohort study to evaluate the efficacy of empirical non-carbapenem antibiotics for treating ESBL-B. Electronic medical records of individuals who were diagnosed with ESBL-B were reviewed between January 2010 and December 2014 at four university hospitals in Korea. Patients were classified into non-carbapenem and carbapenem groups according to the empirical antibiotic regimen. Patients treated with appropriate empirical antibiotics and who subsequently received carbapenems as definitive therapy were included in the analysis. The inverse probability of treatment weights, a statistical method that adjusts baseline statistics by giving weights based on propensity score, was used. During the study period, 232 adequately treated patients with ESBL-B were included in the analysis: 49 patients in the non-carbapenem group and 183 in the carbapenem group. The baseline characteristics and severity of infection were similar after propensity score weighting. The 30-day mortality rates for the two groups were not statistically significantly different (non-carbapenems 6.3% and carbapenems 11.4%; P = 0.42). In a multivariate analysis, empirical treatment with non-carbapenem antibiotics was not associated with 30-day all-cause mortality (HR 1.02, 95% CI 0.99–1.06, P = 0.14). In a subgroup analysis, empirical treatment with piperacillin-tazobactam was also not associated with 30-day all-cause mortality (HR 1.21, 95% CI 0.37–4.00, P = 0.75). Appropriate non-carbapenems were not inferior to carbapenems as initial empirical therapy for ESBL-B.     

<Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis> pneumonia in cancer patients without traditional risk factors for infection, 1997–2004

In order to elucidate the spectrum of Stenotrophomonas maltophilia pneumonia in cancer patients without traditional risk factors, 44 cancer patients (cases) with S. maltophilia pneumonia in whom S. maltophilia pneumonia risk factors were not present were compared with two S. maltophilia pneumonia risk groups (controls) including 43 neutropenic non-intensive care unit (ICU) and 21 non-neutropenic ICU patients. The case and control patients had similar demographic and underlying clinical characteristics. Compared with case patients with S. maltophilia pneumonia, neutropenic patients had higher exposure to carbapenem antibiotics (58 vs. 41%; p < 0.03), more frequent hematologic malignancy (95 vs. 64%; p < 0.0003), and they presented with concurrent bacteremia more often (23 vs. 0%; p < 0.0005). Patients with S. maltophilia pneumonia in the ICU needed vasopressor therapy more frequently than cases (62 vs. 5%; p < 0.0001). Hospital-acquired S. maltophilia pneumonia was more common among controls than cases (98 vs. 61%; p < 0.000002). Among the cases, 15 (34%) received outpatient oral antimicrobial therapy, while 29 were hospitalized and eight (28%) were subsequently admitted to the ICU. The mean duration of ICU stay, even among these eight patients (19 ± 40 days), was comparable to that of patients with neutropenia (23 ± 26 days) and those who developed S. maltophilia pneumonia during their ICU stay (34 ± 22 days; p = 0.46). The overall infection-associated mortality in the 108 patients with S. maltophilia pneumonia was 25%. Twenty percent of patients without traditional risk factors for S. maltophilia pneumonia died due to progressive infection. In a multivariate logistic regression analysis, only admission to the ICU predicted death (odds ratio 33; 95% confidence interval, 4.51–241.2; p < 0.0006). The results of this study indicate S. maltophilia pneumonia is a serious infection even in non-neutropenic, non-ICU patients with cancer. This work was presented in part at the 15th European Congress of Clinical Microbiology and Infectious Diseases, Copenhagen, Denmark, April 2–5, 2005 (abstract no P1374) and at the 45th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington D.C., December 16–19, 2005 (abstract no K-1535).     

Monotherapy versus combination antibiotic therapy for patients with bacteremic <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis> community-acquired pneumonia

The purpose of this study was to examine the impact of antimicrobial monotherapy vs combination therapy on length of stay and mortality for patients with Streptococcus pneumoniae pneumonia. Thirty-nine percent of patients received monotherapy, while 61% received combination therapy. Although there was no significant difference in mortality (OR 1.25, 95% CI = 0.25–6.8), there was a significant increase in length of stay for patients who received combination therapy (p = 0.02). Patients with bacteremic pneumococcal pneumonia treated with empiric combination therapy had no significant difference in mortality; however, they did have increased length of stay after adjusting for severity of illness. Randomized controlled trials are needed to determine what is the optimal empiric antimicrobial regime for patients with community-acquired pneumonia.