Bloodstream infections: evolution and trends in the microbiology workload, incidence, and etiology, 1985-2006

Candida spp.: the burden of a microorganism in a microbiology department

There is no precise information available on the entire workload of isolating a specific microorganism in a clinical microbiology laboratory, and the costs associated with it have not been specifically estimated. In this descriptive retrospective study conducted at the microbiology department of a general teaching hospital from January 2021 to December 2022, we assessed the workload associated with identifying Candida species in all types of clinical samples and patients. Costs were estimated from data obtained from the hospital's finance department and microbiology laboratory cost records. In 2 years, 1,008,231 samples were processed at our microbiology department, of which 8,775 had one or more Candida spp. isolates (9,683 total isolates). Overall, 5,151 samples with Candida spp. were identified from 2,383 inpatients. We isolated Candida spp. from 515.3 samples/100,000 population/year and from 92 samples/1,000 hospital admissions/year. By sample type, 90.8% were superficial, mainly mucosal. Only 9.1% Candida spp. were isolated from deep, usually sterile, samples, being mostly from ordinarily sterile fluids. Candida albicans was the main species (58.5%) identified, followed by C. parapsilosis complex, C. glabrata, C. tropicalis, and C. krusei. In admitted patients, the incidences of samples with Candida spp. isolates were 302.7 samples/100,000 population/year and 54 samples/1,000 admissions/year. The average cost of isolating and identifying Candida spp. was estimated at 25€ per culture-positive sample. To our knowledge, this is the first attempt to gage the workload and costs of Candida spp. isolation at a hospital microbiology department. These data can help assess the burden and significance of Candida isolation at other institutions and also help design measures for streamlining.

IMPORTANCE

We believe that this work is of interest because at present, there is no really accurate information available on the total workload involved in isolating a specific microorganism in a clinical microbiology laboratory. The costs related to this have also not been described. We have described the unrestricted workload of Candida spp. in all types of samples for all types of species and patients. We believe that this information would be necessary to collect and share this information as well as to collect it in a standardized way to know the current situation of Candida spp. workload in all clinical microbiology laboratories.

Bloodstream infections: trends and evolution of incidence and etiology in a 12-year period (2010-2021)

INTRODUCTION

The epidemiological evolution of bloodstream infections (BSIs) in the last decade is not clearly defined. Our aim was to analyze the changes in the workload in our institution and to describe the evolution of the incidence and etiology of BSIs in a 12-year period, including the COVID-19 pandemic.

METHODS

All blood cultures received in the laboratory of a tertiary general hospital between 2010 and 2021 were analyzed. Bloodstream infection episodes refer to each episode of bacteremia or fungemia in each patient. Incidence rates per 1000 admissions and per 100,000 population were calculated.

RESULTS

No significant changes in the incidence of BSI episodes/1000 admissions were observed (mean, 31.1), while estimated population-based incidences showed declining trends (mean, 182.8/100,000 inhabitants). There was a slight increase in BSI episodes per 1000 admissions caused by Gram-negatives (mean, 16.6/1000 admissions) and E. coli was the most frequent pathogen (mean, 8.5/1000 admissions). There was no significant rise in episodes caused by ESBL- and carbapenemase-producing E. coli or K. pneumoniae, with a decline in those caused by methicillin-resistant S. aureus. A spike in BSI episodes, fungal BSIs and catheter-related infections was detected in 2020, during the COVID-19 outbreak.

CONCLUSIONS

No clear increase in the incidence of BSI episodes was detected in our center over this period. Gram-negatives are the most frequent etiology, with no clear rise in antimicrobial resistance phenotypes. The COVID-19 pandemic accounted for a small increase in BSI episodes in 2020, probably related to the increase of catheter-related infections.

Differences in clinical outcomes of bloodstream infections caused by Klebsiella aerogenes, Klebsiella pneumoniae and Enterobacter cloacae: a multicentre cohort study

BACKGROUND

Klebsiella aerogenes has been reclassified from Enterobacter to Klebsiella genus due to its phenotypic and genotypic similarities with Klebsiella pneumoniae. It is unclear if clinical outcomes are also more similar. This study aims to assess clinical outcomes of bloodstreams infections (BSI) caused by K. aerogenes, K. pneumoniae and Enterobacter cloacae, through secondary data analysis, nested in PRO-BAC cohort study.

METHODS

Hospitalized patients between October 2016 and March 2017 with monomicrobial BSI due to K. aerogenes, K. pneumoniae or E. cloacae were included. Primary outcome was a composite clinical outcome including all-cause mortality or recurrence until 30 days follow-up. Secondary outcomes were fever ≥ 72 h, persistent bacteraemia, and secondary device infection. Multilevel mixed-effect Poisson regression was used to estimate the association between microorganisms and outcome.

RESULTS

Overall, 29 K. aerogenes, 77 E. cloacae and 337 K. pneumoniae BSI episodes were included. Mortality or recurrence was less frequent in K. aerogenes (6.9%) than in E. cloacae (20.8%) or K. pneumoniae (19.0%), but statistical difference was not observed (rate ratio (RR) 0.35, 95% CI 0.08 to 1.55; RR 0.42, 95% CI 0.10 to 1.71, respectively). Fever ≥ 72 h and device infection were more common in K. aerogenes group. In the multivariate analysis, adjusted for confounders (age, sex, BSI source, hospital ward, Charlson score and active antibiotic therapy), the estimates and direction of effect were similar to crude results.

CONCLUSIONS

Results suggest that BSI caused by K. aerogenes may have a better prognosis than E. cloacae or K. pneumoniae BSI.

Prognostic differences in sepsis caused by gram-negative bacteria and gram-positive bacteria: a systematic review and meta-analysis

BACKGROUND

Bacteria are the main pathogens that cause sepsis. The pathogenic mechanisms of sepsis caused by gram-negative and gram-positive bacteria are completely different, and their prognostic differences in sepsis remain unclear.

METHODS

The PubMed, Web of Science, Cochrane Library, and Embase databases were searched for Chinese and English studies (January 2003 to September 2023). Observational studies involving gram-negative (G (-))/gram-positive (G (+)) bacterial infection and the prognosis of sepsis were included. The stability of the results was evaluated by sensitivity analysis. Funnel plots and Egger tests were used to check whether there was publication bias. A meta-regression analysis was conducted on the results with high heterogeneity to identify the source of heterogeneity. A total of 6949 articles were retrieved from the database, and 45 studies involving 5586 subjects were included after screening according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-seven high-quality studies and 18 moderate-quality studies were identified according to the Newcastle‒Ottawa Scale score. There was no significant difference in the survival rate of sepsis caused by G (-) bacteria and G (+) bacteria (OR 0.95, 95% CI 0.70-1.28). Subgroup analysis according to survival follow-up time showed no significant difference. The serum concentrations of C-reactive protein (CRP) (SMD = 0.39, 95% CI 0.02-0.76), procalcitonin (SMD = 1.95, 95% CI 1.32-2.59) and tumor necrosis factor-alpha (TNF-α) (MD = 0.31, 95% CI 0.25-0.38) in the G (-) bacterial infection group were significantly higher than those in the G (+) bacterial infection group, but there was no significant difference in IL-6 (SMD = 1.33, 95% CI - 0.18-2.84) and WBC count (MD = - 0.15, 95% CI - 0.96-00.66). There were no significant differences between G (-) and G (+) bacteria in D dimer level, activated partial thromboplastin time, thrombin time, international normalized ratio, platelet count, length of stay or length of ICU stay. Sensitivity analysis of the above results indicated that the results were stable.

CONCLUSION

The incidence of severe sepsis and the concentrations of inflammatory factors (CRP, PCT, TNF-α) in sepsis caused by G (-) bacteria were higher than those caused by G (+) bacteria. The two groups had no significant difference in survival rate, coagulation function, or hospital stay. The study was registered with PROSPERO (registration number: CRD42023465051).

Sources of primary bloodstream infections in internal medicine patients - a cohort study

PURPOSE

To describe the sources of bloodstream infections (BSIs) in internal-medicine patients, on admission and during hospitalization, and to determine the proportion of BSIs in which no secondary cause could be defined (i.e., primary-BSI).

METHODS

We analyzed all BSIs at the internal-medicine wards of the two campuses of the Hadassah Hebrew-University Medical Center, during 2017-2018. We defined the BSI source of each event (secondary, Central-line associated BSI (CLABSI) or primary non-CLABSI) and compared BSIs present on admission (POA) to hospital acquired (HA).

RESULTS

There were 595 patient-unique BSI events, 316 (53.1%) POA-BSI and 279 (46.9%) HA-BSI. Overall, 309 (51.9%) were secondary, 194 (32.6%) primary non-CLABSI and 92 (15.5%) CLABSI. Primary non-CLABSI in the POA-BSI group was 20.6% vs. 46.2% in the HA-BSI group (p = 0.001). The length of hospital stay (LOS) of the HA-BSI group was longer than in the POA-BSI group (mean LOS, 19 days vs. 13.6 days, p = 0.01) and mortality rate was higher (48.7% vs. 19%, p = 0.001). Staphylococcus aureus was more common in primary non-CLABSI than in CLABSI and secondary BSI (29.5%, 12.8% and 16.2%, respectively).

CONCLUSIONS

The proportion of primary non-CLABSI among HA-BSI events is very high (46.2%). The absence of any plausible source for these BSIs, and the fact that in our hospital more than 90% of patients in medicine wards have peripheral lines, suggests that these may be a possible source for primary non-CLABSIs. Measures to prevent peripheral-line associated BSI (PLABSI), like those implemented successfully for the prevention of CLABSI, should be considered.

Risk factors associated with inappropriate empirical antimicrobial treatment in bloodstream infections. A cohort study

Introduction: Bloodstream infections (BSI) are a major cause of mortality all over the world. Inappropriate empirical antimicrobial treatment (i-EAT) impact on mortality has been largely reported. However, information on related factors for the election of i-EAT in the treatment of BSI in adults is lacking. The aim of the study was the identification of risk-factors associated with the use of i-EAT in BSI. Methods: A retrospective, observational cohort study, from a prospective database was conducted in a 400-bed acute-care teaching hospital including all BSI episodes in adult patients between January and December 2018. The main outcome variable was EAT appropriation. Multivariate analysis using logistic regression was performed. Results: 599 BSI episodes were included, 146 (24%) received i-EAT. Male gender, nosocomial and healthcare-associated acquisition of infection, a high Charlson Comorbidity Index (CCI) score and the isolation of multidrug resistant (MDR) microorganisms were more frequent in the i-EAT group. Adequation to local guidelines' recommendations on EAT resulted in 91% of appropriate empirical antimicrobial treatment (a-EAT). Patients receiving i-EAT presented higher mortality rates at day 14 and 30 when compared to patients with a-EAT (14% vs. 6%, p = 0.002 and 22% vs. 9%, p < 0.001 respectively). In the multivariate analysis, a CCI score ≥3 (OR 1.90 (95% CI 1.16-3.12) p = 0.01) and the isolation of a multidrug resistant (MDR) microorganism (OR 3.79 (95% CI 2.28-6.30), p < 0.001) were found as independent risk factors for i-EAT. In contrast, female gender (OR 0.59 (95% CI 0.35-0.98), p = 0.04), a correct identification of clinical syndrome prior to antibiotics administration (OR 0.26 (95% CI 0.16-0.44), p < 0.001) and adherence to local guidelines (OR 0.22 (95% CI 0.13-0.38), p < 0.001) were identified as protective factors against i-EAT. Conclusion: One quarter of BSI episodes received i-EAT. Some of the i-EAT related factors were unmodifiable (male gender, CCI score ≥3 and isolation of a MDR microorganism) but others (incorrect identification of clinical syndrome before starting EAT or the use of local guidelines for EAT) could be addressed to optimize the use of antimicrobials.

A multicenter investigation of 2,773 cases of bloodstream infections based on China antimicrobial surveillance network (CHINET)

Background

Bloodstream infections (BSIs), especially hospital-acquired BSIs, are a major cause of morbidity and mortality. However, the details about the pathogens and antimicrobial resistance profile of BSIs across China are still lacking.

Methods

An investigation was conducted in 10 large teaching hospitals from seven geographic regions across China in 2016 based on China Antimicrobial Surveillance Network (CHINET) to profile the clinical and etiological features of BSIs.

Results

A total of 2,773 cases of BSIs were identified, a majority (97.3%) of which were monomicrobial. Overall, 38.4% (1,065/2,773) were community-acquired BSIs (CABSIs), and 61.6% (1,708/2,773) were hospital-acquired BSIs (HABSIs). Of the 2,861 pathogenic BSI isolates, 67.5% were Gram-negative bacteria, 29.6% were Gram-positive bacteria, and 2.9% were fungi. The top BSI pathogens were Escherichia coli, Klebsiella pneumoniae, coagulase-negative Staphylococci (CNS), Staphylococcus aureus, Enterococci, and Acinetobacter baumannii. Escherichia coli and K. pneumoniae isolates showed low susceptibility to penicillins, cephalosporins (except ceftazidime and cefepime), and ampicillin-sulbactam (13.1%-43.4% susceptible); moderate susceptibility (about 60% susceptible) to ceftazidime, cefepime, and aztreonam; and high susceptibility (>90%) to β-lactam/β-lactamase inhibitor combinations other than ampicillin-sulbactam, except K. pneumoniae strains to piperacillin-tazobactam (59.2% susceptible). HABSIs were associated with significantly higher prevalence of carbapenem-resistant and extended-spectrum β-lactamases-producing K. pneumoniae, methicillin-resistant S. aureus, methicillin-resistant CNS, and ampicillin-resistant Enterococci than CABSIs. Overall, 42.0% of the BSI due to S. aureus strains were resistant to methicillin.

Conclusions

The findings about BSIs in teaching hospitals across China add more scientific evidence to inform the appropriate management of the disease.

Multidrug-Resistant Acinetobacter baumannii May Cause Patients to Develop Polymicrobial Bloodstream Infection

Background

The incidence of polymicrobial bloodstream infections is increasing, the clinical characteristics of polymicrobial Acinetobacter baumannii bloodstream infections (AB-BSI) are unclear, and there are no reports of polymicrobial AB-BSI in mainland China. Therefore, our objective was to identify the clinical characteristics, risk factors, and outcomes of polymicrobial AB-BSI versus monomicrobial AB-BSI.

Methods

A retrospective survey of all patients with AB-BSI from January 1, 2015, to December 31, 2019, and their clinical data were collected and analyzed by reviewing electronic medical records. All data were compared and analyzed between groups of monomicrobial and polymicrobial AB-BSI. Risk factors for polymicrobial AB-BSI were assessed using multivariable logistic regression analysis.

Results

A total of 204 patients were included, of which 39 (19.1%) were patients with polymicrobial AB-BSI. The main sources of the pathogenicity of polymicrobial Acinetobacter baumannii bloodstream infections were skin and soft tissue (38.5% vs. 16.4%, p=0.002). Resistance to piperacillin/tazobactam as an independent factor for polymicrobial AB-BSI was found in multivariate analysis. Patients with polymicrobial AB-BSI had longer hospital stays compared to those with monomicrobial AB-BSI. However, there was no significant difference in mortality between the two groups.

Conclusions

Polymicrobial AB-BSI accounted for a significant proportion among all AB-BSI, and it did not influence mortality but was related to slightly longer total hospital stays. Multidrug resistance was associated with the development of polymicrobial AB-BSI but does not directly lead to polymicrobial AB-BSI, whereas resistance to piperacillin/tazobactam was highly correlated with polymicrobial AB-BSI. Therefore, while treating A. baumannii bloodstream infections, clinicians cannot ignore the multidrug-resistant A. baumannii, especially piperacillin/tazobactam-resistant A. baumannii, which may predispose to the development of polymicrobial AB-BSI.

Mortality predictive factors of people living with human immunodeficiency virus and bloodstream infection

INTRODUCTION

Portugal has one of the highest mortality rates for people living with HIV (PLWHIV) in Europe. After antiretroviral therapy introduction, HIV-associated mortality declined, included the one associated with bloodstream infection (BSI). However it is still high, and European data are scarce . Therefore, characterizing BSI and defining prognostic factors may improve our approach.

METHODS

This was a 10-year retrospective study of predictive factors for 30-day and 3-year mortality in PLWHIV with BSI in a tertiary infectious diseases ward.

RESULTS

Of 2134 PLWHIV admissions, 145 (6.8%) had a BSI, mostly respiratory and catheter-related bacteremia and globally community-acquired. Nosocomial infections occurred in 42 (36%) cases, mostly caused by Enterococcus spp, Staphylococcus aureus, and Candida spp. PLWHIV with a BSI had higher 30-day mortality (27%) compared to those without a BSI (14%). APACHE II score, corticotherapy, and current intravenous drug use (IDU) had a prognostic impact on 30-day mortality. Three-year survival was 54% in PLWHIV with a BSI; a CD4 <200 cells, vascular or chronic pulmonary disease, and lymphoma were prognostic factors.

CONCLUSIONS

Patients with a BSI were more likely to present advanced HIV disease, have more comorbidities, a longer length of stay, and higher 30-day mortality. IDU and severity of infection determined the short-term prognosis. Three-year mortality was primarily influenced by lower CD4 cell counts, hematological tumor, and cardiopulmonary comorbidities. Systemic corticotherapy may influence nosocomial BSI and short-term prognosis.

Pathogenesis of Gram-Negative Bacteremia

Gram-negative bacteremia is a devastating public health threat, with high mortality in vulnerable populations and significant costs to the global economy. Concerningly, rates of both Gram-negative bacteremia and antimicrobial resistance in the causative species are increasing. Gram-negative bacteremia develops in three phases. First, bacteria invade or colonize initial sites of infection. Second, bacteria overcome host barriers, such as immune responses, and disseminate from initial body sites to the bloodstream. Third, bacteria adapt to survive in the blood and blood-filtering organs. To develop new therapies, it is critical to define species-specific and multispecies fitness factors required for bacteremia in model systems that are relevant to human infection. A small subset of species is responsible for the majority of Gram-negative bacteremia cases, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii The few bacteremia fitness factors identified in these prominent Gram-negative species demonstrate shared and unique pathogenic mechanisms at each phase of bacteremia progression. Capsule production, adhesins, and metabolic flexibility are common mediators, whereas only some species utilize toxins. This review provides an overview of Gram-negative bacteremia, compares animal models for bacteremia, and discusses prevalent Gram-negative bacteremia species.

Epidemiology and microbiology of Gram-negative bloodstream infections in a tertiary-care hospital in Beijing, China: a 9-year retrospective study

Background: Gram-negative bacterial bloodstream infections (BSIs) are associated with high morbidity and mortality. The present study examines the incidence, clinical characteristics, microbiological features, drug resistance and mortality associated with Gram-negative bacterial BSIs at a tertiary-care hospital in Beijing, China.Methods: This retrospective cohort study of patients with Gram-negative bacterial BSIs was performed between 1 January 2010 and 31 December 2018 at the Chinese People^,s Liberation Army General Hospital.Results: A total of 6867 episodes of Gram-negative bacterial BSIs occurred among 3199 patients over 9 years. The overall incidence of Gram-negative bacterial BSIs fluctuated from 2.30 to 2.55 episodes per 1000 admissions over 9 years. Escherichia coli was the major pathogen (34.3%). The antibiotic resistance of ESBLs-producing E. coli was higher than non-ESBLs producing E. coli including the majority of antibiotics, but to carbapenems (0.7% VS 5.1%). Between 2010 and 2018, the overall mortality of Gram-negative bacterial BSIs decreased from 11.41% to 9.05% (X² = 6.95, P = 0.434).Conclusions: Cephalosporins and carbapenem antibiotics were considered as the optimal treatment for patients with Gram-negative bacterial BSIs except for A. baumannii, which was treated according to the drug sensitivity or multidrug combination.

Admitted AIDS-associated Kaposi sarcoma patients: Indications for admission and predictors of mortality

Kaposi sarcoma (KS) is an AIDS-defining angioproliferative malignancy associated with high morbidity and mortality. Most KS patients in regions with high incidence such as sub-Saharan Africa present late with advanced stage disease. Admitted KS patients have high mortality rates. Factors associated with mortality of admitted KS patients are poorly defined.We conducted a retrospective file review to ascertain reasons for admission and identify factors associated with mortality of admitted HIV-associated (epidemic) KS patients in Zambia. Baseline study variables were collected, and patients were retrospectively followed from admission to time of discharge or death.Mortality rate for admitted epidemic KS patients was high at 20%. The most common reasons for admission included advanced KS disease, severe anemia, respiratory tract infections, and sepsis. The majority (48%) of admitted patients had advanced clinical stage with visceral involvement on admission. Clinical predictors of mortality on univariate analysis included visceral KS [odds ratio (OR) = 13.74; 95% confidence interval (95% CI) = 1.68-113; P = 0.02), fever (OR = 26; 95% CI = 4.85-139; P = .001), and sepsis (OR = 35.56; 95% CI = 6.05-209; P = .001). Baseline hemoglobin levels (5.6 vs 8.2 g/dL; P = .001) and baseline platelet counts (63 x 10^9/L vs 205 x 10^9/L; P = .01) were significantly lower in mortalities vs discharges. Baseline white cell counts were higher in mortalities vs discharges (13.78 x 10^9/L vs 5.58 x 10^9/L; P = .01), and HIV-1 viral loads at the time of admission were higher in mortalities vs discharges (47,607 vs 40 copies/μL; P = .02). However, only sepsis (or signs and symptoms of sepsis) were independently associated with mortality after controlling for confounders.In conclusion, common reasons for admission of epidemic KS patients include advanced disease, severe anemia, respiratory tract infections, and signs and symptoms of sepsis. Signs and symptoms of sepsis are independent predictors of mortality in these patients.

Clinical characteristics and risk factors of polymicrobial Staphylococcus aureus bloodstream infections

Background

Although Staphylococcus aureus bloodstream infections (SA-BSI) are a common and important infection, polymicrobial SA-BSI are infrequently reported. The aim of this study was to investigate the clinical characteristics and risk factors of polymicrobial SA-BSI in comparison with monomicrobial SA-BSI.

Methods

A single-center retrospective observational study was performed between Jan 1, 2013, and Dec 31, 2018 at a tertiary hospital. All patients with SA-BSI were enrolled, and their clinical data were gathered by reviewing electronic medical records.

Results

A total of 349 patients with SA-BSI were enrolled including 54 cases (15.5%) with polymicrobial SA-BSI. In multivariable analysis, burn injury (adjusted odds ratio [OR], 7.04; 95% confidence interval [CI], 1.71–28.94), need of blood transfusion (aOR, 2.72; 95% CI, 1.14–6.50), use of mechanical ventilation (aOR, 3.11; 95% CI, 1.16–8.30), the length of prior hospital stay (aOR, 1.02; 95% CI, 1.00–1.03), and pneumonia as primary site of infection (aOR, 4.22; 95% CI, 1.69–10.51) were independent factors of polymicrobial SA-BSI. In comparison with monomicrobial SA-BSI, patients with polymicrobial SA-BSI had longer length of ICU stay [median days, 23(6.25,49.25) vs. 0(0,12), p < 0.01] and hospital stay [median days, 50(21.75,85.75) vs. 28(15,49), p < 0.01], and showed a higher 28-day mortality (29.6% vs. 15.3%, p = 0.01).

Conclusions

Burn injury, blood transfusion, mechanical ventilation, the length of prior hospital stay, and pneumonia as a primary site of infection are independent risk factors for polymicrobial SA-BSI. In addition, patients with polymicrobial SA-BSI might have worse outcomes compared with monomicrobial SA-BSI.

Clinical Characteristics And Risk Factors In Mixed-Enterococcal Bloodstream Infections

Purpose

Although the enterococcal bloodstream infections (EBSI) are often observed in clinic, the mixed-EBSI are few reported. The aim of this study was to investigate the clinical characteristics and risk factors of mixed-EBSI in comparison with monomicrobial EBSI (mono-EBSI).

Methods

A single-center retrospective observational study was performed between Jan 1, 2013 and Dec 31, 2018 in a tertiary hospital. All patients with EBSI were enrolled, and their data were collected by reviewing electronic medical records.

Results

A total of 451 patients with EBSI were enrolled including 157 cases (34.8%) with mixed-EBSI. The most common co-pathogens were Coagulase-negative Staphylococcus (26.86%), followed by Acinetobacter baumannii (23.43%) and Klebsiella pneumoniae (8.57%). In multivariable analysis, burn injury (adjusted odds ratio [aOR], 7.39; 95% confidence interval [CI], 2.69-20.28), and length of prior hospital stay (aOR, 1.01; 95% CI, 1.00-1.02) were associated with mixed-EBSI. Patients with mixed-EBSI developed with more proportion of septic shock (19% vs. 31.8%, p=0.002), prolonged length of intensive care unit (ICU) stay [9(0,25) vs. 15(2.5,36), p<0.001] and hospital stay [29(16,49) vs. 33(18.5,63), p=0.031]. The mortality was not significantly different between mixed-EBSI and mono-EBSI (p=0.219).

Conclusion

A high rate of mixed-EBSI is among EBSI, and Acinetobacter baumannii is the second predominant co-existed species, except for Coagulase-negative Staphylococcus. Burn injury and length of prior hospital stay are independent risk factors for mixed-EBSI. Although the mortality is not different, patients with mixed-EBSI might have poor outcomes in comparison with mono-EBSI, which merits more attention by physicians in the future.

A Simulated Application of the Hartford Hospital Aminoglycoside Dosing Nomogram for Plazomicin Dosing Interval Selection in Patients With Serious Infections Caused by Carbapenem-Resistant Enterobacterales

PURPOSE

In the Phase III Study of Plazomicin Compared With Colistin in Patients With Infection Due to Carbapenem-Resistant Enterobacteriaceae (CARE), plazomicin was studied for the treatment of critically ill patients with infections caused by carbapenem-resistant Enterobacterales. Initial plazomicin dosing was guided by creatinine clearance (CrCl) and subsequent doses adjusted by therapeutic drug monitoring to achieve AUC_0-24 exposures within a target range (210-315 mg∙h/L). We applied the Hartford nomogram to evaluate whether this clinical tool could reduce plazomicin troughs levels and increase the proportion of patients within the target AUC range.

METHODS

Thirty-seven patients enrolled in cohorts 1 or 2 of CARE were eligible for analyses. Observed 10-hour concentrations after the initial dose were plotted on the Hartford nomogram to determine an eligible dosing interval group (q24h, q36h or q48h). On the basis of baseline CrCl, a 15- or 10-mg/kg dose was simulated with the nomogram-recommended dosing interval. The proportion of patients in each dosing interval group with a trough ≥3 mg/L (trough threshold associated with serum creatinine increases ≥0.5 mg/dL in product label) was quantified. Simulated interval-normalized AUC_0-24 was compared with the target AUC range.

FINDINGS

Among the 28 patients with a CrCl ≥60 mL/min, the nomogram recommended every-24-hour dosing in 61% and an extended-interval (q36h or q48h) in 39% of patients. For patients with a CrCl ≥30-59 mL/min (n = 9), the nomogram recommended every-24-hour dosing and an extended-interval in 22% and 78% of patients, respectively. Among both renal function cohorts, exposure simulation with the nomogram significantly reduced the proportion of patients with trough concentrations ≥3 mg/L (CrCl ≥60 mL/min cohort: 91% vs 9%, P < 0.001; CrCl ≥30-59 mL/min cohort, 100% vs 0%, P < 0.001). Relative to the observed mean (SD) AUC_0-24 of 309 mg∙h/mL (96 mg∙h/mL), simulation of extended intervals resulted in a mean interval-normalized AUC_0-24 of 210 mg∙h/mL (40 mg∙h/mL) in all patients eligible for an extended interval, resulting in a similar proportion (49% vs 54%) of patients within the target AUC_0-24 range after the first dose.

IMPLICATIONS

Application of the Hartford nomogram successfully reduced the likelihood of elevated plazomicin trough concentrations while improving AUC exposures in these patients with carbapenem-resistant Enterobacterales infections.

FDG-PET/CT for Detecting an Infection Focus in Patients With Bloodstream Infection: Factors Affecting Diagnostic Yield

PURPOSE

To investigate the diagnostic performance of F-fluoro-2-deoxy-D-glucose (FDG) PET/ CT for the detection of an infection focus in patients with a bloodstream infection (BSI) and to identify factors influencing the diagnostic yield of FDG-PET/CT.

METHODS

This retrospective single-center study included 185 consecutive patients with a BSI who underwent an FDG-PET/CT scan for the detection of an infection focus between 2010 and 2017. The final diagnosis at hospital discharge was used as reference standard. Diagnostic performance of FDG-PET/CT for the detection of an infection focus was assessed, and logistic regression analyses were performed to identify factors associated with FDG-PET/CT yield.

RESULTS

An infection focus was identified on FDG-PET/CT in 120 (64.8%) of 185 patients. FDG-PET/CT achieved a sensitivity of 80.2%, specificity of 79.6%, positive predictive value of 90.8%, and a negative predictive value of 61.4% for detecting an infection focus in patients with a BSI. Blood cultures positive for enterococci (odds ratio, 0.14; P = 0.019) and days of antibiotic treatment before FDG-PET/CT (odds ratio, 0.94 per day increase; P = 0.014) were statistically significant independent predictors of a lower odds of detecting an infection focus on FDG-PET/CT. In patients who received antibiotics for less than 7 days before FDG-PET/CT, an infection focus was found in 71% (56/79). In patients who received antibiotics for 8 to 14 days before FDG-PET/CT, an infection focus was found in 52% (22/42). After 15 to 21 days of antibiotic treatment, an infection focus was found in 61% (8/13), and for 22 days or more, this declined to 38% (5/13).

CONCLUSIONS

FDG-PET/CT is a useful method for detecting an infection focus in patients with BSI. However, longer duration of antibiotic treatment before FDG-PET/CT and bacteremia with enterococci reduce the diagnostic yield of FDG-PET/CT. These factors should be taken into account when considering an FDG-PET/CT scan for this indication.

Epidemiology and microbiology of Gram-positive bloodstream infections in a tertiary-care hospital in Beijing, China: a 6-year retrospective study

Background

Gram-positive bacterial bloodstream infections (BSIs) are serious diseases associated with high morbidity and mortality. The following study examines the incidence, clinical characteristics and microbiological features, drug resistance situations and mortality associated with Gram-positive BSIs at a large Chinese tertiary-care hospital in Beijing, China.

Methods

A retrospective cohort study of patients with Gram-positive BSIs was performed between January 1, 2011, and June 31, 2017, at the Chinese People^’s Liberation Army General Hospital. The patients’ data were collected and included in the reviewing electronic medical records.

Results

A total of 6887 episodes of Gram-positive BSIs occurred among 4275 patients over 6 years, and there were 3438 significant BSI episodes 69% of these cases were healthcare-associated, while 31% were community-associated. The overall incidence of Gram-positive BSIs fluctuated from 7.26 to 4.63 episodes per 1000 admissions over 6 years. Malignancy was the most common comorbidity and indwelling central intravenous catheter was the most common predisposing factor for BSI. Staphylococci were the major pathogen (65.5%), followed by Enterococcus spp:(17.5%), Streptococcus spp.(7.1%) and other bacterial pathogens (9.9%). The resistance rates of Staphylococci and E.faecium to penicillins were more than 90%. the vancomycin-resistant isolates were E. faecium (4.1%) and staphylococcus epidermidis (0.13%); and only E.faecalis and E.faecium showed resistance to linezolid (3.8% and 3.1%). Between 2011 and 2017, the overall mortality of Gram-positive BSIs decreased from 6.27 to 4.75% (X² = 0.912, p = 0.892). Neverthess, the mortality in the ICU decreased from 60.46 to 47.82%, while in the general ward it increased from 39.54 to 52.18%.

Conclusions

The morbidity and mortality of Gram-positive BSIs have showed downward trends. Vancomycin and linezolid are still consider the best treatment for patients with Gram-positive BSIs.

Antimicrobial Nonsusceptibility of Gram-Negative Bloodstream Isolates, Veterans Health Administration System, United States, 2003-20131

Bacteremia caused by gram-negative bacteria is associated with serious illness and death, and emergence of antimicrobial drug resistance in these bacteria is a major concern. Using national microbiology and patient data for 2003–2013 from the US Veterans Health Administration, we characterized nonsusceptibility trends of community-acquired, community-onset; healthcare-associated, community-onset; and hospital-onset bacteremia for selected gram-negative bacteria (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, and Acinetobacter spp.). For 47,746 episodes of bacteremia, the incidence rate was 6.37 episodes/10,000 person-years for community-onset bacteremia and 4.53 episodes/10,000 patient-days for hospital-onset bacteremia. For Klebsiella spp., P. aeruginosa, and Acinetobacter spp., we observed a decreasing proportion of nonsusceptibility across nearly all antimicrobial drug classes for patients with healthcare exposure; trends for community-acquired, community-onset isolates were stable or increasing. The role of infection control and antimicrobial stewardship efforts in inpatient settings in the decrease in drug resistance rates for hospital-onset isolates needs to be determined.

Incidence of Multidrug-Resistant Organism Among Children Admitted to Pediatric Intensive Care Unit in a Developing Country

AIM

Multidrug-resistant infections are an increasingly common condition particularly in critical care units. This study aimed to determine the incidence and types of resistant bacteria acquired in a pediatric intensive care unit (PICU) of a university hospital.

SUBJECT AND METHODS

A prospective study was conducted during the year 2016. All children aged below 16 years were studied for infection development and pattern of susceptibility to various groups of antibiotics.

RESULTS

A total of 264 patients were admitted to the PICU: 16 patients had community-acquired infection (CAI), 23 had hospital-acquired infection, and 24 patients had PICU-acquired infection (with 36 episodes) which is equivalent to 14.75 case/1,000 patient days. The study revealed high incidence of resistant organisms in the PICU but more important is the appearance of multi- and extreme drug-resistant bacteria in CAI. The study revealed that gram-negative bacteria were more prevalent in PICU, especially Klebsiella (30.5%), Acinetobacter baumanii (22.22%), and Pseudomonas (16.67%). Infection with resistant organisms in the PICU caused initial treatment failure and increased fourfold risk of mortality.

CONCLUSION

The incidence of resistant bacteria especially gram-negative pathogens was very high in the PICU. The top three resistant organisms of concern were Klebsiella, Acinetobacter, and Pseudomonas. This is a global concern that necessitates new strategies.

Reproducible measurement of vancomycin MICs within the susceptible range in Staphylococcus aureus by a broth microdilution method with a "quasi-continuum" gradient of antibiotic concentrations

The availability of reproducible broth microdilution (BMD) methods including inter log₂ antibiotic dilutions for measuring Staphylococcus aureus (SA) vancomycin minimum inhibitory concentrations (MICs) within the susceptible range is needed to elucidate the impact of vancomycin MICs on clinical outcomes of invasive SA infections. Here, we report on the development of a very precise BMD method that incorporates the following incremental antibiotic concentrations: 0.50, 0.62, 0.75, 0.87, 1.0, 1.25, 1.40, 1.50, 1.60, 1.75, and 2.0 μg/mL. The intra- and inter-assay coefficients of variation of this method were around 20%. The mean of the differences in MIC values for all isolates obtained across two independent runs performed at one center was 0.04 μg/mL [95% confidence interval (CI), 0.011-0.07 μg/mL] and that for ten isolates measured at two different centers was 0.04 μg/mL (95% CI, 0-13 μg/mL). Vancomycin MIC values differed by less than 0.1 μg/mL between runs for most isolates. Storage of isolates at -20 °C for up to 3 months had no impact on the vancomycin MIC values. The mean vancomycin MIC values obtained by the Etest using a standard inoculum (0.5 McFarland) were significantly higher (p ≤ 0.001) than those measured by BMD and the MIC values measured by the two methods correlated poorly (Rho, 0.319; p = 0.148). Nevertheless, the mean MIC values measured by the Etest using lower inocula (10⁷ or 10⁶ CFU/mL) and those measured by BMD were comparable and correlated significantly (p = 0.004 for 10⁷ CFU/mL and p = 0.029 for 10⁶ CFU/mL).

Results of an early intervention programme for patients with bacteraemia: analysis of prognostic factors and mortality

Background

Bacteraemia is a common cause of morbidity and mortality in patients admitted to hospital. The aim of this study is to analyse the results of a two-year programme for the early optimisation of antibiotic treatment in patients admitted to the Costa del Sol Hospital (Marbella. Spain).

Methods

A prospective two-year cohort study was conducted, evaluating all episodes of bacteraemia at the Costa del Sol Hospital. Epidemiological and microbiological characteristics, any modification of the initial antibiotic treatment, prognostic risk stratification, early mortality related to the episode of bacteraemia, and mortality after the seventh day, were included in the analysis.

Results

Seven hundred seventy-three episodes of bacteraemia were treated, 61.6% males and 38.4% females. The mean age was 65.2 years. The condition was most commonly acquired in the community (41.4%). The bacteraemia was most frequently urological in nature (30.5%), and E coli was the microorganism most frequently isolated (31.6%). In 51.1% of the episodes, a modification was made to optimise the treatment. In the first week, 8.2% died from bacteraemia, and 4.5% had died when they were located. The highest rates of death were associated with older patients, nosocomial acquisition, no source, McCabe score rapidly fatal, Charlson index ≥3, Pitt index ≥3 and treatment remained unmodified.

Conclusion

The existence of bacteraemia control programmes and teams composed of clinicians who are experienced in the treatment of infectious diseases, can improve the disease outcome by enabling more severe episodes of bacteraemia to be recognised and their empirical treatment optimised.

Antimicrobial resistance patterns, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients with hematological disease: A monocenter retrospective study in China

The aim of this retrospective analysis was to evaluate the antimicrobial resistance, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients in a single hematological center in China. A retrospective case-control study of 157 adult hematological patients with 168 episodes of E coli bacteremia was initiated from April 2012 to July 2015. Antimicrobial susceptibility as well as antimicrobial co-resistance rates were analyzed. Clinical features and outcomes were also studied. In addition, risk factors for septic shock and death were investigated. Among the 553 positive blood isolates during the study period, the prevalence of E coli was 33.3% and ESBL production strains represented 61.9% of those examined. In all the E coli strains isolated, 85.6% were multidrug-resistance (MDR), 2.4% were extensive drug resistance (XDR), and 6.0% were resistant to carbapenems. More MDR phenotype was noted in ESBL-EC strains (98.6% vs 62.8%, P<.001) and isolates from neutropenic patients (98.6% vs 62.8%, P < .001). In the antimicrobial susceptibility test, carbapenems and amikacin exhibited not only higher in vitro activity against E coli (94.0% and 92.0%, respectively), but lower co-resistance rates to other antibiotics. Carbapenem resistant strains retained full sensitivity to tigecycline and 60% to amikacin. Piperacillin/tazobatam was the third sensitive drug to both ESBL-EC (77.1%) and non-ESBL-EC (86.0%). In our series, 81.6% episodes received appropriate initial antibiotic treatment and no significant decrease in it was found in bacteremia due to ESBL E coli and patients with neutropenia, septic shock. Septic shock was noted in 15.5% patients and the overall 30-day mortality rate was 21.7%. Multivariate analysis revealed that induction chemotherapy (OR 2.126; 95% CI 1.624-11.332; P = .003) and polymicrobial infection (OR 3.628; 95% CI 1.065-21.219; P = .041) were risk factors for septic shock, whereas male (OR 2.223; 95% CI 1.132-12.022; P < .01) and septic shock (OR 52.359; 95% CI 19.951-292.690; P = .030) were risk factors for death.In the hematology department, ESBL-producing and MDR are widely prevalent in E coli bacteremia which is still a major life-threatening problem, especially for patients with septic shock. For empirical antimicrobial therapy, combination based on aminoglycoside, especially amikacin, will be helpful to increase the antimicrobial coverage against ESBL-EC while combining tigecycline with aminoglycoside should be considered for seriously carbapenem-resistant infectious patients.

Diagnosis of neonatal sepsis using 16S rRNA polymerase chain reaction

The gold standard for detecting bacterial sepsis is blood culture. However, the sensitivity of blood culture is low and the results take 48-72 h. Molecular assays for the detection of bacterial DNA permit early detection of a bacterial cause as the turnaround time is 6-8 h. We undertook an evaluation of the performance of universal bacterial primer (16S rRNA) polymerase chain reaction (PCR) in the diagnosis of neonatal sepsis at a tertiary care medical college teaching hospital. 16S rRNA PCR was positive in all cases of blood culture proven sepsis. PCR revealed 95.6% sensitivity, 100% specificity, 100% positive predictive value and 91.2% negative predictive value and so appears to be a useful tool for the early diagnosis of bacterial neonatal sepsis.

Molecular assays for the diagnosis of sepsis in neonates

BACKGROUND

Microbial cultures for diagnosis of neonatal sepsis have low sensitivity and reporting delay. Advances in molecular microbiology have fostered new molecular assays that are rapid and may improve neonatal outcomes.

OBJECTIVES

To assess the diagnostic accuracy of various molecular methods for the diagnosis of culture-positive bacterial and fungal sepsis in neonates and to explore heterogeneity among studies by analyzing subgroups classified by gestational age and type of sepsis onset and compare molecular tests with one another.

SEARCH METHODS

We performed the systematic review as recommended by the Cochrane Diagnostic Test Accuracy Working Group. On 19 January 2016, we searched electronic bibliographic databases (the Cochrane Library, PubMed (from 1966), Embase (from 1982), and CINAHL (from 1982)), conference proceedings of the Pediatric Academic Societies annual conference (from 1990), clinical trial registries (ClinicalTrials.gov, International Standard Randomised Controlled Trial Number (ISRCTN) registry, and World Health Organization (WHO) International Clinical Trials Platform (ICTRP) Search portal), and Science Citation Index. We contacted experts in the field for studies.

SELECTION CRITERIA

We included studies that were prospective or retrospective, cohort or cross-sectional design, which evaluated molecular assays (index test) in neonates with suspected sepsis (participants) in comparison with microbial cultures (reference standard).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodologic quality of the studies and extracted data. We performed meta-analyses using the bivariate and hierarchical summary receiver operating characteristic (HSROC) models and entered data into Review Manager 5.

MAIN RESULTS

Thirty-five studies were eligible for inclusion and the summary estimate of sensitivity was 0.90 (95% confidence interval (CI) 0.82 to 0.95) and of specificity was 0.93 (95% CI 0.89 to 0.96) (moderate quality evidence). We explored heterogeneity by subgroup analyses of type of test, gestational age, type of sepsis onset, and prevalence of sepsis and we did not find sufficient explanations for the heterogeneity (moderate to very low quality evidence). Sensitivity analyses by including studies that analyzed blood samples and by good methodology revealed similar results (moderate quality evidence).

AUTHORS' CONCLUSIONS

Molecular assays have the advantage of producing rapid results and may perform well as 'add-on' tests.

14-Year Survey in a Swedish County Reveals a Pronounced Increase in Bloodstream Infections (BSI). Comorbidity - An Independent Risk Factor for Both BSI and Mortality

OBJECTIVES

we assessed the incidence, risk factors and outcome of BSI over a 14-year period (2000-2013) in a Swedish county.

METHODS

retrospective cohort study on culture confirmed BSI among patients in the county of Östergötland, Sweden, with approximately 440,000 inhabitants. A BSI was defined as either community-onset BSI (CO-BSI) or hospital-acquired BSI (HA-BSI).

RESULTS

of a total of 11,480 BSIs, 67% were CO-BSI and 33% HA-BSI. The incidence of BSI increased by 64% from 945 to 1,546 per 100,000 hospital admissions per year during the study period. The most prominent increase, 83% was observed within the CO-BSI cohort whilst HA-BSI increased by 32%. Prescriptions of antibiotics in outpatient care decreased with 24% from 422 to 322 prescriptions dispensed/1,000 inhabitants/year, whereas antibiotics prescribed in hospital increased by 67% (from 424 to 709 DDD per 1,000 days of care). The overall 30-day mortality for HA-BSIs was 17.2%, compared to 10.6% for CO-BSIs, with an average yearly increase per 100,000 hospital admissions of 2 and 5% respectively. The proportion of patients with one or more comorbidities, increased from 20.8 to 55.3%. In multivariate analyses, risk factors for mortality within 30 days were: HA-BSI (2.22); two or more comorbidities (1.89); single comorbidity (1.56); CO-BSI (1.21); male (1.05); and high age (1.04).

CONCLUSION

this survey revealed an alarming increase in the incidence of BSI over the 14-year study period. Interventions to decrease BSI in general should be considered together with robust antibiotic stewardship programmes to avoid both over- and underuse of antibiotics.

[The clinical feature and outcomes of severe aplastic anemia patients suffered from bacteremia following antithymocyte globulin]

Objective: To assess the clinical feature and outcomes of severe aplastic anemia (SAA) patients suffered from bacteremia following antithymocyte globulin (ATG). Methods: A total of 264 cases hospitalized in our hospital between Jan 2000 and July 2011 were enrolled into this study. We evaluated the associated pathogens of bacteremia, analyzed the risk factors by Logistic regression and estimated the overall survival (OS) by Kaplan-Meier method for the cohort of patients. Results: Bloodstream infections occurred in 49 patients, with a median age of 20 (4-62) years, including 38 cases with very SAA (VSAA) and 11 SAA patients. The median time of bacteremia was 13 (2-233) days following ATG administration. The most common microbiologically were Enterobacteriaceae (28.4% ), Pseudomonas aeruginosa (20.9% ) and Klebsiella pneumonia (14.9% ). Almost half (46.9% ) of these bacteria were resistant to most or all available antibacterial classes. Univariate and multivariate analyses demonstrated that VSAA, infections during previous week before ATG treatment were risk factors for bacteremia. The 3 and 6 months response rates (10.6% and 17.0% ) were poor in the patients with bloodstream infections, which were significantly lower than those patients without infections (35.6% and 55.6%, respectively, both P<0.001). The estimated 5-year OS were 36.4% (95%CI 21.3% to 51.5%) and 74.5% (95%CI 68.4% to 80.7%) in the two groups, respectively (P<0.001). Conclusions: ①VSAA has higher risk of bacteremia than SAA; ②Infections during previous week before ATG administration was a risk factor for bacteremia; ③ The outcomes of SAA or VSAA patients suffered from bacteremia following ATG was poor.

The Effect of a Nationwide Infection Control Program Expansion on Hospital-Onset Gram-Negative Rod Bacteremia in 130 Veterans Health Administration Medical Centers: An Interrupted Time-Series Analysis

BACKGROUND

The Veterans Health Administration (VHA) introduced the Methicillin-Resistant Staphylococcus aureus (MRSA) Prevention Initiative in March 2007. Although the initiative has been perceived as a vertical intervention focusing on MRSA, it also expanded infection prevention and control programs and resources. We aimed to assess the horizontal effect of the initiative on hospital-onset (HO) gram-negative rod (GNR) bacteremia.

METHODS

This retrospective cohort included all patients who had HO bacteremia due to Escherichia coli, Klebsiella species, or Pseudomonas aeruginosa at 130 VHA facilities from January 2003 to December 2013. The effects were assessed using segmented linear regression with autoregressive error models, incorporating autocorrelation, immediate effect, and time before and after the initiative. Community-acquired (CA) bacteremia with same species was also analyzed as nonequivalent dependent controls.

RESULTS

A total of 11 196 patients experienced HO-GNR bacteremia during the study period. There was a significant change of slope in HO-GNR bacteremia incidence rates from before the initiative (+0.3%/month) to after (-0.4%/month) (P < .01), while CA GNR incidence rates did not significantly change (P = .08). Cumulative effect of the intervention on HO-GNR bacteremia incidence rates at the end of the study period was estimated to be -43.2% (95% confidence interval, -51.6% to -32.4%). Similar effects were observed in subgroup analyses of each species and antimicrobial susceptibility profile.

CONCLUSIONS

Within 130 VHA facilities, there was a sustained decline in HO-GNR bacteremia incidence rates after the implementation of the MRSA Prevention Initiative. As these organisms were not specifically targeted, it is likely that horizontal components of the initiative contributed to this decline.

High vancomycin MICs within the susceptible range in Staphylococcus aureus bacteraemia isolates are associated with increased cell wall thickness and reduced intracellular killing by human phagocytes

Vancomycin minimum inhibitory concentrations (MICs) at the upper end of the susceptible range for Staphylococcus aureus have been associated with poor clinical outcomes of bloodstream infections. We tested the hypothesis that high vancomycin MICs in S. aureus bacteraemia isolates are associated with increased cell wall thickness and suboptimal bacterial internalisation or lysis by human phagocytes. In total, 95 isolates were evaluated. Original vancomycin MICs were determined by Etest. The susceptibility of S. aureus isolates to killing by phagocytes was assessed in a human whole blood assay. Internalisation of bacterial cells by phagocytes was investigated by flow cytometry. Cell wall thickness was evaluated by transmission electron microscopy. Genotypic analysis of S. aureus isolates was performed using a DNA microarray system. Vancomycin MICs were significantly higher (P=0.006) in isolates that were killed suboptimally (killing index <60%) compared with those killed efficiently (killing index >70%) and tended to correlate inversely (P=0.08) with the killing indices. Isolates in both killing groups were internalised by human neutrophils and monocytes with comparable efficiency. The cell wall was significantly thicker (P=0.03) in isolates in the low killing group. No genotypic differences were found between the isolates in both killing groups. In summary, high vancomycin MICs in S. aureus bacteraemia isolates were associated with increased cell wall thickness and reduced intracellular killing by phagocytes.

Bloodstream infections in internal medicine

Bloodstream infections (BSI) carry a heavy burden of morbidity and mortality in modern internal medicine wards (IMW). These wards are often filled with elderly subjects with several risk factors for BSI, such as multiple comorbidities, polypharmacy, immunosuppression, and indwelling devices. Diagnosing BSI in such a setting might require a high degree of suspicion, since the clinical presentation could be affected by underlying conditions and concomitant medications, which might delay the administration of an appropriate antimicrobial therapy, an event strongly and unfavorably influencing survival. Furthermore, selecting the appropriate antimicrobial therapy to treat these patients is becoming an increasingly complex task in which all possible benefits and costs should be carefully analyzed from patient and public health perspectives. Only a specialized, continuous, and interdisciplinary approach could really improve the management of IMW patients in an era of increasing antimicrobial resistance and complexity of care.

A Multicenter Evaluation of Blood Culture Practices, Contamination Rates, and the Distribution of Causative Bacteria

BACKGROUND

The prognostic value of blood culture testing in the diagnosis of bacteremia is limited by contamination.

OBJECTIVES

In this multicenter study, the aim was to evaluate the contamination rates of blood cultures as well as the parameters that affect the culture results.

MATERIALS AND METHODS

Sample collection practices and culture data obtained from 16 university/research hospitals were retrospectively evaluated. A total of 214,340 blood samples from 43,254 patients admitted to the centers in 2013 were included in this study. The blood culture results were evaluated based on the three phases of laboratory testing: the pre-analytic, the analytic, and the post-analytic phase.

RESULTS

Blood samples were obtained from the patients through either the peripheral venous route (64%) or an intravascular catheter (36%). Povidone-iodine (60%) or alcohol (40%) was applied to disinfect the skin. Of the 16 centers, 62.5% have no dedicated phlebotomy team, 68.7% employed a blood culture system, 86.7% conducted additional studies with pediatric bottles, and 43.7% with anaerobic bottles. One center maintained a blood culture quality control study. The average growth rate in the bottles of blood cultures during the defined period (1259 - 26,400/year) was 32.3%. Of the growing microorganisms, 67% were causative agents, while 33% were contaminants. The contamination rates of the centers ranged from 1% to 17%. The average growth time for the causative bacteria was 21.4 hours, while it was 36.3 hours for the contaminant bacteria. The most commonly isolated pathogens were Escherichia coli (22.45%) and coagulase-negative staphylococci (CoNS) (20.11%). Further, the most frequently identified contaminant bacteria were CoNS (44.04%).

CONCLUSIONS

The high contamination rates were remarkable in this study. We suggest that the hospitals' staff should be better trained in blood sample collection and processing. Sterile glove usage, alcohol usage for disinfection, the presence of a phlebotomy team, and quality control studies may all contribute to decreasing the contamination rates. Health policy makers should therefore provide the necessary financial support to obtain the required materials and equipment.

Epidemiology and microbiology of nosocomial bloodstream infections: analysis of 482 cases from a retrospective surveillance study

In many traditional Chinese medicine (TCM) hospitals, most patients are elderly with chronic diseases. Nosocomial bloodstream infections (nBSIs) are an important cause of morbidity and mortality. A retrospective surveillance study was performed to examine the epidemiology and microbiology of nBSIs in a TCM hospital from 2009 to 2011. A total of 482 patients with nBSIs were included in the study period. The incidence rate was 5.7/1000 admissions. Escherichia coli (25.5%) was the most common Gram-negative and coagulase-negative staphylococcus (CoNS) (14.1%) was the most common Gram-positive organism isolated. One-third of the E. coli and Klebsiella pneumoniae isolated from the nBSIs were the third-generation cephalosporin-resistant. Half of the Acinetobacter species isolates were resistant to imipenem. Of all the CoNS isolates, 90.7% were resistant to methicillin. Carbapenems and glycopeptide were the most frequently used for nBSI therapy. Only about one-third of patients (157/482) received appropriate empirical therapy. Septic shock, hemodialysis, Pitt bacteremia score >4, urinary tract infection, and appropriate empirical therapy were most strongly associated with 28-d mortality. The incidence of nBSIs was low in the TCM hospital but the proportion of nBSIs due to antibiotic-resistant organisms was high. A high Pitt bacteremia score was one of the most important risk factors for mortality in nBSIs. Therefore, the implementation of appropriate empirical therapy is crucial to improve the clinical outcome of nBSIs.

Evaluation of the BD BACTEC FX blood volume monitoring system as a continuous quality improvement measure

The yield of blood cultures is proportional to the volume of blood cultured. We evaluated an automatic blood volume monitoring system, recently developed by Becton Dickinson within its BACTEC EpiCenter module, that calculates mean volumes of negative aerobic bottles and generates boxplots and histograms. First, we evaluated the filling degree of 339 aerobic glass blood cultures by calculating the weight-based volume for each bottle. A substantial amount of the bottles (48.3%) were inadequately filled. Evaluation of the accuracy of the monitoring system showed a mean bias of -1.4 mL (-15.4%). Additional evaluation, using the amended software on 287 aerobic blood culture bottles, resulted in an acceptable mean deviation of -0.3 mL (-3.3%). The new software version was also tested on 200 of the recently introduced plastic bottles, which will replace the glass bottles in the near future, showing a mean deviation of +2.8 mL (+26.7%). In conclusion, the mean calculated volumes can be used for the training of a single phlebotomist. However, filling problems appear to be masked when using them for phlebotomist groups or on wards. Here, visual interpretation of boxplots and histograms can serve as a useful tool to observe the spread of the filling degrees and to develop a continuous improvement program. Re-adjustment of the software has proven to be necessary for use with plastic bottles. Due to our findings, BD has developed further adjustments to the software for validated use with plastic bottles, which will be released soon.

The NOVA score: a proposal to reduce the need for transesophageal echocardiography in patients with enterococcal bacteremia

BACKGROUND

Frequency of enterococcal bloodstream infection (E-BSI) is increasing, and the number of episodes complicated by infective endocarditis (IE) varies. Performing transesophageal echocardiography (TEE) in all patients with E-BSI is costly and time-consuming. Our objectives were to identify patients with E-BSI who are at very low risk of enterococcal IE (and therefore do not require TEE) and to compare the outcome of E-BSI in patients with/without IE.

METHODS

Between September 2003 and October 2012, we performed a prospective cohort study (all patients with E-BSI) and a case-control study (patients with/without enterococcal IE) in our center.

RESULTS

We detected 1515 patients with E-BSI and 65 with enterococcal IE (4.29% of all episodes of E-BSI, 16.7% of patients with E-BSI who underwent transthoracic echocardiography, and 35.5% of all patients with E-BSI who underwent TEE). We developed a bedside predictive score for enterococcal IE-Number of positive blood cultures, Origin of the bacteremia, previous Valve disease, Auscultation of heart murmur (NOVA) score-based on the following variables: Number of positive blood cultures (3/3 blood cultures or the majority if more than 3), 5 points; unknown Origin of bacteremia, 4 points; prior heart Valve disease, 2 points; Auscultation of a heart murmur, 1 point (receiver operating characteristic = 0.83). The best cutoff corresponded to a score ≥4 (sensitivity, 100%; specificity, 29%). A score <4 points suggested a very low risk for enterococcal IE and that TEE could be obviated.

CONCLUSIONS

Enterococcal IE may be more frequent than generally thought. Depending on local prevalence of endocarditis, application of the NOVA score may safely obviate echocardiography in 14%-27% of patients with E-BSI.

Invasive Candidiasis due to Candida Norvegensis in a Liver Transplant Patient: Case Report and Literature Review

Candida norvegensis is an emerging fluconazole-resistant pathogen isolated in most cases from skin and mucous membranes of immunocompromized patients. Documented invasive candidiasis (IC) due to C. norvegensis has been rarely reported, thus the clinical features of patients at risk for this pathogen are poorly defined. We report a liver transplant patient who developed IC due to C. norvegensis and review other cases of C. norvegensis IC published in the literature.

Micafungin at physiological serum concentrations shows antifungal activity against Candida albicans and Candida parapsilosis biofilms

We assessed the in vitro activity of micafungin against preformed Candida biofilms by measuring the concentration of drug causing the most fungal damage and inhibition of regrowth. We studied 37 biofilm-producing Candida spp. strains from blood cultures. We showed that micafungin was active against planktonic and sessile forms of Candida albicans strains and moderately active against Candida parapsilosis sessile cells. Concentrations of micafungin above 2 μg/ml were sufficiently high to inactivate regrowth of Candida sessile cells.

Epidemiology of multi-drug resistant organisms in a teaching hospital in oman: a one-year hospital-based study

Background. Antimicrobial resistance is increasingly recognized as a global challenge. A few studies have emerged on epidemiology of multidrug resistant organisms in tertiary care settings in the Arabian Gulf. Aim. To describe the epidemiology of multi-drug resistant organisms (MDRO) at Sultan Qaboos University Hospital, a tertiary hospital in Oman. Methods. A retrospective review of MDRO records has been conducted throughout the period from January 2012 till December 2012. Organisms were identified and tested by an automated identification and susceptibility system, and the antibiotic susceptibility testing was confirmed by the disk diffusion method. Results. Out of the total of 29,245 admissions, there have been 315 patients registered as MDRO patients giving an overall prevalence rate of 10.8 (95% CI 9.3, 12.4) MDRO cases per 1000 admissions. In addition, the prevalence rate of MDRO isolates was 11.2 (95% CI 9.7, 12.9) per 1000 admissions. Overall, increasing trends in prevalence rates of MDRO patients and MDRO isolates were observed throughout the study period. Conclusion. Antimicrobial resistance is an emerging challenge in Oman. Continuous monitoring of antimicrobial susceptibility and strict adherence to infection prevention guidelines are essential to prevent proliferation of MDRO. Along such quest, stringent antibiotic prescription guidelines are needed in the country.

What is the impact of a rapid diagnostic E-test in the treatment of patients with Gram-negative bacteraemia?

OBJECTIVE

To evaluate the influence of a rapid diagnostic test (RDT) in antibiotic therapeutic decisions in non-paediatric patients with Gram-negative bacteraemia (GNB).

PATIENTS AND METHODS

A RDT consisting of a direct antibiogram was used on blood isolates of GNB. GNB were also identified and sensitivity tests were performed according to standard criteria. Information on empirical treatment was registered (T1), as well as the antibiotic administered once the results of the RDT were available (T2). Finally, we noted the ideal antibiotic that the infectious diseases specialist (IDS) would have prescribed (T3). The decision regarding T2 was always taken by the patient's physician or the physician on duty.

RESULTS

A RDT was performed for 248 patients. The most frequently isolated bacterium was Escherichia coli (13% producing extended-spectrum beta-lactamase). T1 was considered appropriate in 74% and appropriate but optimizable in 43%. T2 was considered appropriate in 95%, appropriate but optimizable in 36%, and inappropriate in 5%. The cost of the optimizable treatment (T2) was € 2210, while the cost of the ideal treatment would have been € 416; the saving in antibiotic cost of 1 day of treatment would have been € 1694.

CONCLUSIONS

Treatment prescribed by a non-IDS after a RDT was inappropriate in 5% and optimizable in 36%. It is our recommendation that information provided by a RDT should be interpreted by an IDS to make the information more beneficial both economically and 'ecologically'.

Can procalcitonin differentiate Staphylococcus aureus from coagulase-negative staphylococci in clustered gram-positive bacteremia?

Procalcitonin (PCT) and pro-adrenomedullin (ProADM) have been proposed as diagnostic and prognostic biomarkers of infection. Between July 2009 and January 2012, we studied the role of these biomarkers in 163 patients with clustered gram-positive and gram-negative bacteremia. PCT levels were significantly higher in patients with Staphylococcus aureus and gram-negative bacteremia than those with coagulase-negative staphylococci (CoNS) isolated from blood cultures (P = 0.29 and <0.001, respectively). ProADM levels were only significantly higher in patients with gram-negative bacteremia (median 1.46 nmol/L) than those with CoNS (median 1.01 nmol/L) (P = 0.04). Among patients with CoNS, PCT, and ProADM, levels failed to differentiate blood contamination (medians 0.24 ng/mL and 0.97 nmol/L) from true bacteremia (medians 0.26 ng/mL and 1.14 nmol/L) (P = 0.51 and 0.57, respectively). In cancer patients, PCT (and to a lesser extent, ProADM) was useful in differentiating CoNS from S. aureus and gram-negative bacteremia.

Mixed bloodstream infections involving bacteria and Candida spp

OBJECTIVES

Polymicrobial bloodstream infection (BSI) is an imprecisely defined entity purportedly associated with a worse outcome than monomicrobial BSI. This study examines trends in BSI episodes caused by bacteria and Candida spp. (mixed-BSI) in a large teaching hospital.

METHODS

All episodes of BSI from January 2000 to December 2010 were reviewed. Three groups (n = 54 each) of patients were compared: all adults with mixed-BSI from January 2006 to December 2010 (cases) and randomly selected patients with polybacterial BSI (polyB-BSI) (Control 1) or Candida spp. BSI (Candida-BSI) (Control 2) in this same period.

RESULTS

A total of 139 episodes of mixed-BSI were recorded (0.7% of all BSI, 6.9% of all poly-BSI and 18.0% of all Candida-BSI episodes). The incidence of mixed-BSI was 0.21 cases/1000 admissions, increasing from 0.08 (2000) to 0.34 (2010) cases/1000 admissions (P = 0.007). Mixed-BSI represented 11.8% and 22.9% of all episodes of candidaemia in 2000 and 2010, respectively (P = 0.011). Compared with polyB-BSI, mixed-BSI patients showed fewer malignancies, more frequent nosocomial or intravenous catheter BSI source and less frequent intra-abdominal origin, were more frequently admitted to an intensive care unit (ICU), received more antimicrobials and showed a longer hospital stay and higher mortality. Compared with Candida-BSI, mixed-BSI patients showed more severe underlying diseases, were more frequently admitted to an ICU or oncology-haematology unit, showed a higher APACHE II score, more often progressed to septic shock or multiorgan failure and received more antimicrobials. Mortality was similar.

CONCLUSIONS

Mixed-BSI is a rare, distinct infection with a worse prognosis than polyB-BSI. We were unable to detect differences in the prognosis of mixed-BSI when compared with Candida-BSI.

The preanalytical optimization of blood cultures: a review and the clinical importance of benchmarking in 5 Belgian hospitals

Bloodstream infections remain a major challenge in medicine. Optimal detection of pathogens is only possible if the quality of preanalytical factors is thoroughly controlled. Since the laboratory is responsible for this preanalytical phase, the quality control of critical factors should be integrated in its quality control program. The numerous recommendations regarding blood culture collection contain controversies. Only an unambiguous guideline permits standardization and interlaboratory quality control. We present an evidence-based concise guideline of critical preanalytical determinants for blood culture collection and summarize key performance indicators with their concomitant target values. In an attempt to benchmark, we compared the true-positive rate, contamination rate, and collected blood volume of blood culture bottles in 5 Belgian hospital laboratories. The true-positive blood culture rate fell within previously defined acceptation criteria by Baron et al. (2005) in all 5 hospitals, whereas the contamination rate exceeded the target value in 4 locations. Most unexpected, in each of the 5 laboratories, more than one third of the blood culture bottles were incorrectly filled, irrespective of the manufacturer of the blood culture vials. As a consequence of this shortcoming, one manufacturer recently developed an automatic blood volume monitoring system. In conclusion, clear recommendations for standardized blood culture collection combined with quality control of critical factors of the preanalytical phase are essential for diagnostic blood culture improvement.

Vancomycin MICs do not predict the outcome of methicillin-resistant Staphylococcus aureus bloodstream infections in correctly treated patients

BACKGROUND

Recent studies have reported a greater probability of vancomycin treatment failure in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections caused by strains with a vancomycin MIC ≥ 1.5 mg/L. However, previous reports included patients treated without adjustments based on vancomycin serum levels and with different methods to evaluate MICs, which may render different results.

METHODS

Over a 5 year period (2005-09), vancomycin MICs were determined for 361 MRSA isolates recovered from 309 patients with bloodstream infection using microdilution and the Etest simultaneously. The relationship between the vancomycin MICs determined by each method was assessed. To assess the outcome of patients treated with vancomycin, 104 patients for whom serum vancomycin levels had been determined were selected.

RESULTS

The percentage of MRSA strains with MIC values ≥ 1.5 mg/L according to the Etest was 66.5% compared with only 3.6% according to microdilution. No correlation between mortality and any MIC value obtained with either method was observed, independently of the vancomycin serum levels measured.

CONCLUSIONS

There is a poor correlation between vancomycin MIC values obtained by microdilution and by Etest. No association between mortality rate and any MIC value was observed, not even in patients with suboptimal vancomycin trough serum levels. These data do not support replacing or complementing the standard microdilution test with the Etest for determination of MICs of vancomycin in microbiology laboratories.

The decline of typhoid and the rise of non-typhoid salmonellae and fungal infections in a changing HIV landscape: bloodstream infection trends over 15 years in southern Vietnam

The etiological spectrum of bloodstream infections is variable between industrialized and developing countries and even within a defined location over time. We investigated trends in bloodstream infections at an infectious disease hospital in Ho Chi Minh City, Vietnam, from 1994-2008. Amongst 66,111 blood cultures performed, a clinically relevant pathogen was isolated in 7645 episodes (positivity rate; 116/1000 cultures). Salmonella Typhi was the predominant pathogen until 2002; however, a considerable annual decline in the proportion of S. Typhi was observed (OR 0.6993, 95% CI [0.6885, 0.7103], p<0.0001). Conversely, there was a significant increase in the proportions of non-typhoidal Salmonella (NTS), Cryptococcus neoformans and Penicillium marneffei, concurrent with increasing HIV prevalence. These data document a substantial longitudinal shift in bloodstream infection etiology in southern Vietnam. We propose such changes are related to increasing economic prosperity and HIV prevalence, and this pattern marks a substantial change in the epidemiology of invasive salmonellosis in Southeast Asia.

Characteristics of healthcare-associated and community-acquired Klebsiella pneumoniae bacteremia in Taiwan

OBJECTIVES

Klebsiella pneumoniae is the major cause of community-onset pyogenic infections in Taiwan. We investigated the clinical features and outcomes of community-acquired (CA) and healthcare-associated (HCA) infections among community-onset K. pneumoniae bacteremia.

METHODS

Adult patients with community-onset monomicrobial K. pneumoniae bacteremia were analysed retrospectively at a medical centre in Taiwan over a 4-year period. We compared the clinical characteristics of patients from the CA and HCA groups and identified the risk factors for infection-related mortality.

RESULTS

In a total of 372 patients, HCA infections were observed in 44%. The HCA group had higher Charlson score, the Acute Physiology and Chronic Health Evaluation, version II (APACHE II) score, frequency of malignancy, rates of respiratory tract infection and bacteremia from unknown sources, and higher mortality than the CA group. Diabetes and liver abscess were predominant in the CA group. Whereas old age, APACHE II score >15, malignancy, liver cirrhosis, chronic renal failure, respiratory tract infection, skin and soft tissue infection, and inappropriate antimicrobial therapy were predictors for mortality, HCA bacteremia was not.

CONCLUSIONS

HCA bacteremia showed different characteristics and higher mortality than CA bacteremia, but HCA infection was not an independent risk factor for mortality.

Impact of inadequate empirical therapy on the mortality of patients with bloodstream infections: a propensity score-based analysis

The impact of the adequacy of empirical therapy on outcome for patients with bloodstream infections (BSI) is key for determining whether adequate empirical coverage should be prioritized over other, more conservative approaches. Recent systematic reviews outlined the need for new studies in the field, using improved methodologies. We assessed the impact of inadequate empirical treatment on the mortality of patients with BSI in the present-day context, incorporating recent methodological recommendations. A prospective multicenter cohort including all BSI episodes in adult patients was performed in 15 hospitals in Andalucía, Spain, over a 2-month period in 2006 to 2007. The main outcome variables were 14- and 30-day mortality. Adjusted analyses were performed by multivariate analysis and propensity score-based matching. Eight hundred one episodes were included. Inadequate empirical therapy was administered in 199 (24.8%) episodes; mortality at days 14 and 30 was 18.55% and 22.6%, respectively. After controlling for age, Charlson index, Pitt score, neutropenia, source, etiology, and presentation with severe sepsis or shock, inadequate empirical treatment was associated with increased mortality at days 14 and 30 (odds ratios [ORs], 2.12 and 1.56; 95% confidence intervals [95% CI], 1.34 to 3.34 and 1.01 to 2.40, respectively). The adjusted ORs after a propensity score-based matched analysis were 3.03 and 1.70 (95% CI, 1.60 to 5.74 and 0.98 to 2.98, respectively). In conclusion, inadequate empirical therapy is independently associated with increased mortality in patients with BSI. Programs to improve the quality of empirical therapy in patients with suspicion of BSI and optimization of definitive therapy should be implemented.

Molecular assays in the diagnosis of neonatal sepsis: a systematic review and meta-analysis

BACKGROUND

Microbial cultures for diagnosis of neonatal sepsis suffer from low sensitivity and reporting delay. Advances in molecular microbiology have fostered new molecular assays that are rapid and may improve neonatal outcomes.

OBJECTIVES

We assessed whether molecular assays have sufficient sensitivity (>0.98) and specificity (>0.95) to replace microbial cultures in the diagnosis of neonatal sepsis and explored heterogeneity by use of subgroup analyses based on the type of assay, gestational age of the neonate, and type of sepsis onset.

METHODS

We performed the systematic review as recommended by the Cochrane Diagnostic Test Accuracy Working Group. Electronic bibliographic databases, conference abstracts, personal files, and reference lists of identified articles were searched. We included studies of case-control or consecutive series design, which evaluated molecular assays (index test) in neonates with suspected sepsis (participants) in comparison with microbial cultures (reference standard). Two reviewers independently assessed the methodologic quality of the studies and extracted data.

RESULTS

A bivariate random-effects model was used for meta-analysis of the 23 included studies, and summary estimates of sensitivity and specificity with 95% confidence intervals (CIs) were generated. Mean sensitivity and specificity were 0.90 (95% CI: 0.78-0.95) and 0.96 (95% CI: 0.94-0.97), respectively. Real-time polymerase chain reaction (PCR) and broad-range conventional PCR had higher sensitivity and specificity than other assays. Sufficient data were not available to evaluate gestational-age and sepsis-type subgroups.

CONCLUSION

Molecular assays do not have sufficient sensitivity to replace microbial cultures in the diagnosis of neonatal sepsis but may perform well as "add-on" tests.