Clinical characterization of breakthrough bacteraemia: a survey of 392 episodes

Risk factors for positive follow-up blood cultures in Gram-negative bacteremia among immunocompromised patients with neutropenia

INTRODUCTION

Gram-negative bacillary bloodstream infection (GN-BSI) is a frequent clinical challenge among immunocompromised hosts and is associated with a high mortality. The utility of follow-up blood cultures (FUBCs) for GN-BSI in this population, particularly in the setting of neutropenia, is poorly defined.

METHODS

We conducted a single-center, retrospective cohort study between the period of July 2018 and April 2022 to investigate the utility of FUBCs and delineate risk factors for positive cultures among neutropenic patients with monomicrobial GN-BSI. Univariate logistic regression was performed to assess risk factors associated with positive FUBCs.

RESULTS

Of 206 patients, 98% had FUBCs performed, and 9% were positive. Risk factors for positive FUBCs included multidrug-resistant GN infection (OR 3.26; 95% confidence interval [CI] 1.22-8.72) and vascular catheter source (OR 4.82; CI 1.76-13.17). Among patients lacking these risk factors, the prevalence of positive FUBCs was low (2.8%) and the negative predictive value was 92%. Those with positive and negative FUBCs had similar rates of all-cause mortality (16.7% vs. 16.6%; p = .942) and microbiologic relapse (11.1% vs. 6.0%; p = .401) within 90-days of treatment completion. However, positive FUBCs were associated with prolonged hospitalization and longer duration of antimicrobial therapy.

CONCLUSION

Positive FUBCs were infrequent in neutropenic patients with GN-BSI, and their occurrence did not significantly impact mortality or microbiologic relapse. Risk factors for positive FUBCs included multidrug resistant Gram-negative infection and vascular catheter source. Prospective studies will be necessary to elucidate the benefits and risks of FUBCs when managing GN-BSI in patients with underlying immune compromise.

Follow-up blood cultures in Pseudomonas aeruginosa bacteremia: A potential target for diagnostic stewardship

Objectives

Evidence supporting collection of follow-up blood cultures for Gram-negative bacteremia is mixed. We sought to understand why providers order follow-up blood cultures when managing P. aeruginosa bacteremia and whether follow-up blood cultures in this context are associated with short- and long-term survival.

Methods

We conducted a retrospective cohort study of adult inpatients with P. aeruginosa bacteremia at the University of Maryland Medical Center in 2015-2020. Kaplan-Meier survival curves and Cox regression with time-varying covariates were used to evaluate the association between follow-up blood cultures and time to mortality within 30 days of first positive blood culture. Provider justifications for follow-up blood cultures were identified through chart review.

Results

Of 159 eligible patients, 127 (80%) had follow-up blood cultures, including 9 (7%) that were positive for P. aeruginosa and 10 (8%) that were positive for other organisms. Follow-up blood cultures were typically collected "to ensure clearance" or "to guide antibiotic therapy." Overall, 30-day mortality was 25.2%. After risk adjustment for patient characteristics, follow-up blood cultures were associated with a nonsignificant reduction in mortality risk (hazard ratio, 0.43; 95% confidence interval, 1.08; P = .071). In exploratory analyses, the potential mortality reduction from follow-up blood cultures was driven by their use in patients with Pitt bacteremia scores >0.

Conclusions

Follow-up blood cultures are commonly collected for P. aeruginosa bacteremia but infrequently identify persistent bacteremia. Targeted use of follow-up blood cultures based on severity of illness may reduce unnecessary culturing.

Candida Bloodstream Infections: Changes in Epidemiology and Increase in Drug Resistance

The literature on bloodstream infections (BSIs) have predominantly been biased towards bacteria, given their superior clinical significance in comparison with the other types of microorganisms. Fungal pathogens have epidemiologically received relatively less attention, although they constitute an important proportion of BSI aetiologies. In this review, the authors discuss the clinical relevance of fungal BSIs in the context of Candida species, as well as treatment options for the infections, emphasizing the compelling need to develop newer antifungals and strengthen antimicrobial stewardship programmes in the wake of the rapid spread of antifungal resistance.

Does This Patient Need Blood Cultures? A Scoping Review of Indications for Blood Cultures in Adult Nonneutropenic Inpatients

Guidance regarding indications for initial or follow-up blood cultures is limited. We conducted a scoping review of articles published between January 2004 and June 2019 that reported the yield of blood cultures and/or their impact in the clinical management of fever and common infectious syndromes in nonneutropenic adult inpatients. A total of 2893 articles were screened; 50 were included. Based on the reported incidence of bacteremia, syndromes were categorized into low, moderate, and high pretest probability of bacteremia. Routine blood cultures are recommended in syndromes with a high likelihood of bacteremia (eg, endovascular infections) and those with moderate likelihood when cultures from the primary source of infection are unavailable or when prompt initiation of antibiotics is needed prior to obtaining primary source cultures. In syndromes where blood cultures are low-yield, blood cultures can be considered for patients at risk of adverse events if a bacteremia is missed (eg, patient with pacemaker and severe purulent cellulitis). If a patient has adequate source control and risk factors or concern for endovascular infection are not present, most streptococci or Enterobacterales bacteremias do not require routine follow-up blood cultures.

Limited Clinical Utility of Follow-up Blood Cultures in Patients With Streptococcal Bacteremia: An Opportunity for Blood Culture Stewardship

Background

The value of positive follow-up blood cultures (FUBCs) in streptococcal bacteremia has not been well defined. Therefore, we explored the frequency of and risk factors for positive FUBC in a retrospective cohort of patients with streptococcal bacteremia.

Methods

Adults ≥18 years of age, admitted with at least 1 positive blood culture for Streptococcus spp between 2013 and 2018 followed by at least 1 FUBC, were potentially eligible. Positive FUBCs were defined as cultures positive for the same streptococcal species drawn >24 hours after the index culture. We excluded patients with polymicrobial bacteremia. We compared the characteristics of patients with and without a positive FUBC.

Results

In our single-center cohort, we identified 590 patients with streptococcal bacteremia, and 314 patients met inclusion criteria. Ten patients had FUBC with Streptococcus spp (3.2%), 4 (1.3%) had a contaminant identified, and 3 (1.0%) had a new pathogen isolated. Endocarditis (5 of 10 [50.0%] vs 35 of 304 [11.5%]), epidural abscess (2 of 10 [20%] vs 4 of 304 [1.3%]), and discitis or vertebral osteomyelitis (3 of 10 [30.0%] vs 14 of 304 [4.6%]) were associated with positive FUBC. Patients with positive FUBC had a longer median length of stay (12.9 vs 7.1 days, P = .004) and longer duration of antibiotic treatment (14.9 vs 43.2 days, P = .03).

Conclusions

Follow-up blood cultures among patients with streptococcal BSI are rarely positive. Clinicians could consider limiting follow-up blood cultures in patients at low risk for deep-seated streptococcal infections, persistent bacteremia, or endovascular infection.

Comparison of breakthrough Gram-positive cocci infection during vancomycin vs teicoplanin therapy in patients receiving haematopoietic stem cell transplantation

WHAT IS KNOWN AND OBJECTIVE

Our previous report indicated that teicoplanin (TEIC) caused fewer adverse effects than vancomycin (VCM) in patients with febrile neutropenia (FN) receiving haematopoietic stem cell transplantation (HSCT). However, we observed breakthrough methicillin-resistant-Staphylococcus haemolyticus (MR-S haemolyticus) infection during TEIC therapy in these patients. In this study, we sought to compare the incidence of breakthrough Gram-positive cocci (GPC) infection during VCM and TEIC therapy in this population.

METHODS

A single-centre, retrospective cohort study was conducted. Patients who had received HSCT and were administered VCM (n = 19) or TEIC (n = 38) for FN from 1 September 2011 to 31 August 2019 were enrolled. We compared the incidence of breakthrough GPC infection between the VCM and TEIC groups.

RESULTS

Breakthrough GPC infection during glycopeptide therapy in febrile neutropenic patients received HSCT was observed in three patients (7.9%) in the TEIC group but in none of patients (0%) in the VCM group. MR-S haemolyticus with low glycopeptide susceptibility (TEIC MIC = 2-8 μg/mL, VCM MIC = 2-4 μg/mL) was isolated from blood cultures in all patients with breakthrough GPC infections. All breakthrough infections were cured by changing from TEIC to daptomycin (DAP).

WHAT IS NEW AND CONCLUSION

The incidence of breakthrough GPC infection during glycopeptide therapy in febrile neutropenic HSCT patients was higher in the TEIC group than in the VCM group. MR-S haemolyticus with low glycopeptide susceptibility was isolated from all patients with breakthrough GPC infection and successfully treated with DAP.

Breakthrough and persistent bacteremia due to serotype K1 Klebsiella pneumoniae in an immunocompetent patient

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HvKP caused breakthrough and persistent bacteremia on an immunocompetent patient.

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This is the first reported case of spondylitis due to HvKP.

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A combination of CTRX and GM might be recommended for HvKP bacteremia.

Herein, we report a case of breakthrough and persistent bacteremia due to serotype K1 Klebsiella pneumoniae in an immunocompetent 53- year-old man. He was diagnosed with pyogenic spondylitis owing to back pain and based on magnetic resonance imaging findings. On admission, several imaging studies were taken to search for other abscesses and infective endocarditis; however, there were no significant findings. Additionally, blood cultures were negative. Upon treatment with intravenous ampicillin/sulbactam, the patient’s symptoms improved. However, eleven days after admission, the patient experienced a fever and worsening back pain. Blood cultures were taken again, and K. pneumoniae was detected, which showed sensitivity to ampicillin/sulbactam. Fourteen days after admission, K. pneumoniae was detected again, suggesting breakthrough and persistent bacteremia with K. pneumoniae. The source of the K. pneumoniae infection was unknown. The antimicrobial regimen was changed to a combination of ceftriaxone and gentamicin. Sixty days after admission, the patient was discharged without any sequelae. The isolated K. pneumoniae strains were found to carry rmpA and were confirmed as serotype K1; thus, detected hypervirulent K. pneumoniae (HvKP). HvKP is an increasingly recognized pathotype of K. pneumoniae characterized clinically by its ability to cause organ- or life-threatening infections in healthy persons. To the best of our knowledge, our case is the first report of spondylitis due to confirmed HvKP. Moreover, HvKP caused breakthrough and persistent bacteremia on an immunocompetent patient.

Breakthrough bloodstream infections in critically ill non-neutropenic patients: higher incidence and better survival than non-breakthrough infections

Introduction. Breakthrough bloodstream infections (BSIs) are rare among non-neutropenic patients.Aim. Our goal was to determine the risk factors associated with development of breakthrough BSIs among critically ill non-neutropenic patients and its role in mortality.Methodology. During a 24-month period (August 2016 to July 2018), all BSIs among non-neutropenic patients hospitalized at the University General Hospital of Patras, Greece, were included. Antimicrobial resistance of isolates was interpreted according to EUCAST guidelines. BSIs were considered as breakthrough when blood cultures yielded a pathogen in a patient who, for at least the previous 72 h, had been receiving at least one antibiotic to which the isolated microorganism was susceptible.Results. Among 217 episodes of BSI, 118 (54.4 %) developed a breakthrough infection. Primary BSIs predominated (101; 46.5 %), followed by catheter-related BSIs (56; 25.8 %). Gram-negative bacteria represented the most common pathogens isolated (157; 72.4 %), followed by Gram-positive bacteria (36; 16.6 %) and fungi (36; 16.6 %). Factors independently associated with the development of breakthrough BSIs were immunosuppressive therapy, obesity (body mass index ≥30 kg m^{- 2}), infection by Gram-positive bacteria, noradrenaline dose during 24 h from BSI onset, prior use of colistin and antifungal treatment. Overall 14-day mortality was 23.0 % (50 patients). Multivariate analysis revealed noradrenaline dose during 24 h from BSI onset as an independent predictor of mortality, while appropriate empiric antimicrobial treatment and breakthrough BSI were identified as predictors of good prognosis.Conclusion. Breakthrough BSIs were common among critically ill non-neutropenic patients and these patients were associated with better survival because they were de facto receiving appropriate antibiotics.

Is a single set of negative blood cultures sufficient to ensure clearance of bloodstream infection in patients with Staphylococcus aureus bacteremia? The skip phenomenon

Background

The most recent version of the Infectious Diseases Society of America guidelines for the treatment of methicillin-resistant Staphylococcus aureus infections states that a single set of negative blood cultures is sufficient to demonstrate clearance of bacteremia. However, S. aureus might exhibit fluctuating blood culture positivity, labeled as “the skip phenomenon”. Our objectives were to determine the prevalence of the skip phenomenon in a cohort of hospitalized patients with S. aureus bacteremia and to determine the associated clinical variables.

Methods

We conducted a nested case–control study, using a previous cohort of 757 adult inpatients between July 2006 and June 2011 with ≥ 3 days of S. aureus bacteremia. Each case of S. aureus bacteremia with the skip phenomenon was matched to 2 to 4 controls based on age, gender, and duration of bacteremia. The association of clinical characteristics with the skip phenomenon was analyzed via conditional logistic regression.

Results

Of the 757 patients in the cohort, 29 (4%) had the skip phenomenon. 26 (90%) patients in the cases group were male. The median age was 69.4 years (interquartile range [IQR] 58.7 to 80.3). Although an attempt to match for the duration of bacteremia was done, there was a statistically longer duration in patients with cases as compared to that in controls (median [IQR], 10 [7–12] days, vs 8 [6–10] days; P = 0.015). Accordingly, duration of bacteremia was adjusted for in regression models. Notably, 26 (90%) patients in the case group were receiving chronic immunosuppressive therapy, as compared to 69 (79%) patients in the control group (P = 0.427).

Conclusion

Our findings prompt consideration of a practice chance to obtain serial negative blood cultures to ensure clearance of bacteremia among patients with S. aureus bacteremia.

Electronic supplementary material

The online version of this article (10.1007/s15010-019-01339-w) contains supplementary material, which is available to authorized users.

Current time-to-positivity of blood cultures in febrile neutropenia: a tool to be used in stewardship de-escalation strategies

OBJECTIVES

We aimed to describe the current time-to-positivity (TTP) of blood cultures in individuals with onco-haematological diseases with febrile neutropenia. We assessed the probability of having a multidrug-resistant Gram-negative bacilli (MDR-GNB) bloodstream infection (BSI) 24 h after cultures were taken, to use this information for antibiotic de-escalation strategies.

METHODS

BSI episodes were prospectively collected (2003-2017). When a patient experienced more than one BSI, only one episode was randomly chosen. Time elapsed from the beginning of incubation to a positive reading was observed; TTP was recorded when the first bottle had a positive result.

RESULTS

Of the 850 patient-unique episodes, 323 (38%) occurred in acute leukaemia, 185 (21.8%) in non-Hodgkin's lymphoma and 144 (16.9%) in solid neoplasms. Coagulase-negative staphylococci (225; 26.5%), Escherichia coli (207; 26.1%), Pseudomonas aeruginosa (136; 16%), Enterococcus spp. (81; 9.5%) and Klebsiella pneumoniae (67; 7.9%), were the most frequent microorganisms isolated. MDR-GNB were documented in 126 (14.8%) episodes. Median TTP was 12 h (interquartile range 9-16.5 h). Within the first 24 h, 92.1% of blood cultures were positive (783/850). No MDR-GNB was positive over 24 h. Of the 67 (7.9%) episodes with a TTP ≥24 h, 25 (37.3%) occurred in patients who were already receiving active antibiotics against the isolated pathogen. Most common isolations with TTP ≥24 h were coagulase-negative staphylococci, candidaemia and a group of anaerobic GNB.

CONCLUSIONS

Currently, the vast majority of BSI in individuals with onco-haematological diseases with febrile neutropenia have a TTP <24 h, including all episodes caused by MDR-GNB. Our results support reassessing empiric antibiotic treatment in neutropenic patients at 24 h, to apply antibiotic stewardship de-escalation strategies.

Increased Costs Associated with Bloodstream Infections Caused by Multidrug-Resistant Gram-Negative Bacteria Are Due Primarily to Patients with Hospital-Acquired Infections

The clinical and economic impacts of bloodstream infections (BSI) due to multidrug-resistant (MDR) Gram-negative bacteria are incompletely understood. From 2009 to 2015, all adult inpatients with Gram-negative BSI at our institution were prospectively enrolled. MDR status was defined as resistance to ≥3 antibiotic classes. Clinical outcomes and inpatient costs associated with the MDR phenotype were identified. Among 891 unique patients with Gram-negative BSI, 292 (33%) were infected with MDR bacteria. In an adjusted analysis, only history of Gram-negative infection was associated with MDR BSI versus non-MDR BSI (odds ratio, 1.60; 95% confidence interval [CI], 1.19 to 2.16; P = 0.002). Patients with MDR BSI had increased BSI recurrence (1.7% [5/292] versus 0.2% [1/599]; P = 0.02) and longer hospital stay (median, 10.0 versus 8.0 days; P = 0.0005). Unadjusted rates of in-hospital mortality did not significantly differ between MDR (26.4% [77/292]) and non-MDR (21.7% [130/599]) groups (P = 0.12). Unadjusted mean costs were 1.62 times higher in MDR than in non-MDR BSI ($59,266 versus $36,452; P = 0.003). This finding persisted after adjustment for patient factors and appropriate empirical antibiotic therapy (means ratio, 1.18; 95% CI, 1.03 to 1.36; P = 0.01). Adjusted analysis of patient subpopulations revealed that the increased cost of MDR BSI occurred primarily among patients with hospital-acquired infections (MDR means ratio, 1.41; 95% CI, 1.10 to 1.82; P = 0.008). MDR Gram-negative BSI are associated with recurrent BSI, longer hospital stays, and increased mean inpatient costs. MDR BSI in patients with hospital-acquired infections primarily account for the increased cost.

Clinical Features and Risk Factors for Development of Breakthrough Gram-Negative Bacteremia during Carbapenem Therapy

With the increasing use of carbapenems, carbapenem-resistant Gram-negative bacteria have become a major concern in health care-associated infections. The present study was performed to evaluate the clinical and microbiological features of breakthrough Gram-negative bacteremia (GNB) during carbapenem therapy and to assess risk factors for development of breakthrough GNB. A case-control study was performed at a tertiary hospital from 2005 to 2014. Case patients were defined as individuals whose blood cultures grew Gram-negative bacteria while the patients were receiving carbapenems for at least 48 h before breakthrough GNB. Age-, sex-, and date-matched controls were selected from patients who received carbapenem for at least 48 h and did not develop breakthrough GNB during carbapenem treatment. A total of 101 cases of breakthrough GNB were identified and compared to 100 controls. The causative microorganisms for breakthrough GNB were Stenotrophomonas maltophilia (n = 33), Acinetobacter baumannii (n = 32), Pseudomonas aeruginosa (n = 21), and others (n = 15). Approximately 90% of S. maltophilia isolates were susceptible to levofloxacin and trimethoprim-sulfamethoxazole. The most common infection types were primary bacteremia (38.6%) and respiratory infections (35.6%). More than half of the patients died within a week after bacteremia, and the 30-day mortality rate was 70.3%. In a multivariate analysis, a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization by causative microorganisms were significantly associated with breakthrough GNB. Our data suggest that S. maltophilia, A. baumannii, and P. aeruginosa are the major pathogens of breakthrough GNB during carbapenem therapy, in association with a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization.

Sending repeat cultures: is there a role in the management of bacteremic episodes? (SCRIBE study)

Background

In the management of bacteremia, positive repeat blood cultures (persistent bacteremia) are associated with increased mortality. However, blood cultures are costly and it is likely unnecessary to repeat them for many patients. We assessed predictors of persistent bacteremia that should prompt repeat blood cultures.

Methods

We conducted a retrospective cohort study of bacteremias at an academic hospital from April 2010 to June 2014. We examined variables associated with patients undergoing repeat blood cultures, and with repeat cultures being positive. A nested case control analysis was performed on a subset of patients with repeat cultures.

Results

Among 1801 index bacteremias, repeat cultures were drawn for 701 patients (38.9 %), and 118 persistent bacteremias (6.6 %) were detected. Endovascular source (adjusted odds ratio [aOR], 7.66; 95 % confidence interval [CI], 2.30-25.48), epidural source (aOR, 26.99; 95 % CI, 1.91-391.08), and Staphylococcus aureus bacteremia (aOR, 4.49; 95 % CI, 1.88-10.73) were independently associated with persistent bacteremia. Escherichia coli (5.1 %, P = 0.006), viridans group (1.7 %, P = 0.035) and β-hemolytic streptococci (0 %, P = 0.028) were associated with a lower likelihood of persistent bacteremia. Patients with persistent bacteremia were less likely to have achieved source control within 48 h of the index event (29.7 % vs 52.5 %, P < .001), but after variable reduction, source control was not retained in the final multivariable model.

Conclusions

Patients with S. aureus bacteremia or endovascular infection are at risk of persistent bacteremia. Achieving source control within 48 h of the index bacteremia may help clear the infection. Repeat cultures after 48 h are low yield for most Gram-negative and streptococcal bacteremias.

Risk factors for late recurrent candidaemia. A retrospective matched case-control study

Incidence, risk factors and clinical significance of late recurrent (LR) candidaemia (>1 month between episodes) remains unclear. The 1219 episodes of candidaemia detected from January 1985 to December 2014 were reviewed. We selected all cases with more than one episode separated by at least 30 days after clinical resolution in the interim (cases) and compared each of them with two controls (patients with single episodes of candidaemia). Clinical strains were genotyped to differentiate relapses from re-infection. Eighteen patients (1.48%) had 36 episodes of LR candidaemia (median 4 months). Independent risk factors for recurrence in the multivariate analysis were: underlying gastrointestinal disease (OR 67.16; 95% CI 5.23-861.71; p 0.001) and fungaemia due to Candida parapsilosis (OR 9.10; 95% 1.33-62.00; p 0.02). All episodes of LR candidaemia diagnosed during the first 3 months were due to an intravascular source of infection, whereas in those occurring after 3 months the main source of the disease was the abdomen, followed by endocarditis, and urinary tract. Molecular typing showed that 42.9% of LR candidaemias were relapses and 57.1% were re-infections. Neither time of recurrence nor clinical origin could predict type of recurrence. LR candidaemia is a relatively rare event that is more frequent in patients who have an initial episode of candidaemia due to C. parapsilosis or an underlying gastrointestinal disease. Episodes of LR candidaemia that occur within the first 3 months should prompt an attempt to exclude an intravascular source of infection, whereas those occurring later point to an intra-abdominal origin.

Breakthrough bacteremia in the neonatal intensive care unit: incidence, risk factors, and attributable mortality

BACKGROUND

An episode of breakthrough bacteremia, which was defined as positive blood cultures despite appropriate antibiotic therapy, imposes a treatment challenge in the neonatal intensive care unit (NICU).

METHODS

All episodes of breakthrough bacteremia from a tertiary level NICU in Taiwan between 2004 and 2011 were analyzed and compared with nonbreakthrough bacteremia.

RESULTS

Breakthrough bacteremia was identified in 7.6% (72/942) of neonatal bacteremia, and 43 (59.7%) occurred as recurrent episodes. Gram-negative organisms (41.7%) and fungi (15.3%) accounted for more than half of all microorganisms in breakthrough bacteremia. Compared with nonbreakthrough bacteremia, breakthrough bacteremia was significantly associated with more severe disease, was more likely to require aggressive therapies, and had a higher rate of infectious complications. Previous use of broad-spectrum antibiotics (odds ratio [OR], 7.54; P < .001) and particular microbial etiologies (Pseudomonas aeruginosa: OR, 4.40; P = .025; fungi: OR, 2.70; P = .013) were independent risk factors for developing breakthrough bacteremia. The crude sepsis-attributable mortality rate was greater in breakthrough bacteremia episodes (16.7% vs 6.4%; P = .004), and this condition was independently associated with an increased risk of death (OR, 2.14; 95% confidence interval, 1.04-4.40; P = .040).

CONCLUSION

Breakthrough bacteremia is not uncommon (7.6% of all bacteremia) in NICUs and represents a more severe form of neonatal bacteremia that is independently associated with an increased risk of death.

Delays in appropriate antibiotic therapy for gram-negative bloodstream infections: a multicenter, community hospital study

Background

Gram-negative bacterial bloodstream infection (BSI) is a serious condition with estimated 30% mortality. Clinical outcomes for patients with severe infections improve when antibiotics are appropriately chosen and given early. The objective of this study was to estimate the association of prior healthcare exposure on time to appropriate antibiotic therapy in patients with gram-negative BSI.

Method

We performed a multicenter cohort study of adult, hospitalized patients with gram-negative BSI using time to event analysis in nine community hospitals from 2003-2006. Event time was defined as the first administration of an antibiotic with invitro activity against the infecting organism. Healthcare exposure status was categorized as community-acquired, healthcare-associated, or hospital-acquired. Time to appropriate therapy among groups of patients with differing healthcare exposure status was assessed using Kaplan-Meier analyses and multivariate Cox proportional hazards models.

Results

The cohort included 578 patients with gram-negative BSI, including 320 (55%) healthcare-associated, 217 (38%) community-acquired, and 41 (7%) hospital-acquired infections. 529 (92%) patients received an appropriate antibiotic during their hospitalization. Time to appropriate therapy was significantly different among the groups of healthcare exposure status (log-rank p=0.02). Time to first antibiotic administration regardless of drug appropriateness was not different between groups (p=0.3). The unadjusted hazard ratios (HR) (95% confidence interval) were 0.80 (0.65-0.98) for healthcare-associated and 0.72 (0.63-0.82) for hospital-acquired, relative to patients with community-acquired BSI. In multivariable analysis, interaction was found between the main effect and baseline Charlson comorbidity index. When Charlson index was 3, adjusted HRs were 0.66 (0.48-0.92) for healthcare-associated and 0.57 (0.44-0.75) for hospital-acquired, relative to patients with community-acquired infections.

Conclusions

Patients with healthcare-associated or hospital-acquired BSI experienced delays in receipt of appropriate antibiotics for gram-negative BSI compared to patients with community-acquired BSI. This difference was not due to delayed initiation of antibiotic therapy, but due to the inappropriate choice of antibiotic.

Current management of bloodstream infections

Bloodstream infection (BSI) is a frequent complication of invasive infections. The presence of bacteremia has therapeutic and prognostic implications. Here we review recent changes in the epidemiology, diagnosis and treatment of BSI (excluding candidemia). The evidence of the impact of healthcare-association in many community-onset episodes and the increase in drug-resistant pathogens causing BSI in the community and hospitals is reviewed. The emergence of molecular methods as an alternative tool for the diagnosis of BSI and novel aspects of clinical management, particularly of some multidrug-resistant organisms. Several quality indicators related to the diagnosis and management of bacteremia in hospitals are proposed.

Oral cryotherapy reduces mucositis and improves nutrition - a randomised controlled trial

AIM AND OBJECTIVE

To investigate if oral cryotherapy during myeloablative therapy may influence frequency and severity of mucositis, nutritional status and infection rate after bone marrow transplantation.

BACKGROUND

Patients treated with intensive myeloablative treatment before bone marrow transplantation are all at risk to develop mucositis. Oral mucositis causes severe pain and oral dysfunction, which can contribute to local and systemic infections and bleeding; it may even interrupt cancer therapy. Oral mucositis also decreases the oral food intake, which increases the risk for malnutrition and infection. Reduced food intake, loss of fat and muscles, alterations in energy and substrate metabolism leads to malnutrition.

DESIGN

A randomised controlled trial with a random assignment to experimental or control group.

METHOD

A stratified randomisation was used with regard to the type of transplantation. Mucositis was measured on WHO mucositis scale. Number of days of total parenteral nutrition, infection rate, weight, albumin levels and days at hospital was compared.

RESULTS

There were significantly fewer patients in the experimental group with mucositis grade 3-4 than in the control group and significantly lower number of days in the hospital (allogeneic patients). Less total parenteral nutrition was needed in the experimental group in both settings, and the S-albumin level was significantly better preserved. No significant difference could be found with regard to infection rate.

CONCLUSION

Oral cryotherapy reduced mucositis, number of hospital days, the need for total parenteral nutrition and resulted in a better nutritional status.

RELEVANCE TO CLINICAL PRACTICE

Nurses caring for patients treated with myeloablative therapy should place high priority to prevent oral mucositis and hereby reduce its side effects.

[A drug addict presenting with complicated tricuspid valve endocarditis]

The right-sided heart valves are affected in about 10% of patients with infective endocarditis. However, the tricuspid valve is the most frequently involved valve in intravenous drug users with infective endocarditis. When treated with antibiotics, the prognosis is considered favorable. Reported here is the case of a drug-addicted patient with polymicrobial (Staphylococcus aureus and Streptococcus pneumoniae) infective endocarditis of the tricuspid valve and a lethal outcome due to multiple organ failure. The indications and options to perform cardiac surgery in patients with infective endocarditis of the tricuspid valve are discussed.

Bacterial substitution of coagulase-negative staphylococci for streptococci on the oral mucosa after hematopoietic cell transplantation

PURPOSE

Coagulase-negative staphylococci (CoNS) are frequently isolated from blood cultures of hematopoietic cell transplantation (HCT) patients. Generally, the use of central venous catheters is recognized as a significant risk factor for CoNS infection, while the impact of CoNS infection from oral ulcerative mucositis, which occurs frequently in HCT, may be underestimated. Here, we examined the bacteria on the buccal mucosa after HCT.

METHODS

Sixty-one patients were examined for bacteria on the buccal mucosa routinely once a week from 1 week before to 3 weeks after allogeneic HCT. Subjects were divided into groups with short and long periods of antibiotic use, and differences in bacterial substitution were evaluated. The relationships between type of HCT (conventional HCT or RIST) and bacterial substitution were also evaluated.

RESULTS

The changes in detection frequencies of CoNS and α-streptococci from before to 3 weeks after HCT were significant (P < 0.05, χ (2) test): 14.5-53.3% and 92.7-53.1%, respectively. Significant bacterial substitution of CoNS for streptococci was observed in the long-term antibiotic use group (P < 0.05, χ (2) test), but also occurred in cases with short-term or no antibiotic use. No relationships between type of HCT (conventional HCT or RIST) were observed.

CONCLUSION

Bacterial substitution of CoNS for streptococci occurred frequently on the buccal mucosa after HCT. In addition to antibiotic use, environmental factors may be involved in bacterial substitution. It is important to consider the presence of oral mucositis in CoNS infection after HCT.

Previous ciprofloxacin exposure is associated with resistance to beta-lactam antibiotics in subsequent Pseudomonas aeruginosa bacteremic isolates

BACKGROUND

Pseudomonas aeruginosa cross-resistance to ceftazidime, imipenem, meropenem, piperacillin, and fluoroquinoles has been shown in experimental studies, but information regarding its impact in the clinical setting is scarce and inconsistent. The aim of this study was to assess whether previous exposure to ciprofloxacin influences on the sensitivity of those antibiotics in subsequent P aeruginosa bacteremic isolates.

METHODS

Patients with P aeruginosa bacteremia were recorded from a blood culture surveillance program (1997-2007). Demographic characteristics, underlying diseases, setting of the infection, source of infection, previous antibiotic exposure, and antibiotic sensitivity were analyzed.

RESULTS

We studied 572 cases of P aeruginosa bacteremia. There were 327 men (57.2%), and the mean age was 61.2 +/- 18 years. The bacteremia was nosocomial in 62.4% of episodes. Resistance rates of P aeruginosa isolates were 15.5% for ceftazidime, 16.7% for imipenem, 11.2% for meropenem, 12.3% for piperacillin-tazobactam, and 23.1% for ciprofloxacin. Exposure to ciprofloxacin during the previous 30 days was an independent predictor of resistance to ceftazidime (odds ratio [OR], 3; 95% confidence interval [CI]: 1.7-5.3; P < .001), imipenem (OR, 2; 95% CI: 1.1-3.7; P = .02), meropenem (OR, 2.7; 95% CI: 1.4-5.3; P = .004), piperacillin-tazobactam (OR, 2.4; 95% CI: 1.3-4.7; P = .007), ciprofloxacin (OR, 2.9; 95% CI: 1.7-4.9; P < .001), and multidrug resistance (OR, 2.5; 95% CI: 1.2-5.2; P = .02).

CONCLUSION

P aeruginosa bacteremic isolates from patients who have been exposed to ciprofloxacin during the 30 days prior to the development of bacteremia have an increased risk of being resistant to ceftazidime, imipenem, meropenem, piperacillin-tazobactam, or ciprofloxacin and to have multidrug resistance.

Life at the front: dissecting bacterial-host interactions at the ocular surface

The ocular surface usually looks quiet, presenting a general impression of biological inactivity. Yet, the ability of the cornea to maintain health while continually exposed to environmental insults, and in the relative absence of immune strategies afforded by other body sites, reflects its complexity. Because it is critical for transparency and, therefore, our survival, the fine structure of the cornea has likely provided the driving force for the evolution of what appears to be a truly remarkable system. While several molecules are now known to participate, we are only beginning to obtain the knowledge to fully explain the mechanisms involved in corneal resistance to infection. Full explanation will require a better understanding of the interplay between microbes and various components of the ocular surface, and of the critical factors determining health as the usual outcome. To understand infectious disease, we need to consider how the scenario changes in conditions associated with susceptibility. What we learn in the process could yield a wealth of potential therapies for a wide variety of diseases of the eye and of other sites.

Microbial and clinical determinants of time-to-positivity in patients with bacteraemia

Time-to-positivity is useful in the diagnosis of catheter-related bacteraemia and as a predictor of an endovascular source in patients with Staphylococcus aureus bacteraemia. However, this parameter has been evaluated for only a limited number of microorganisms. In the present study, time-to-positivity was recorded for 1872 episodes of significant monomicrobial bacteraemia diagnosed at a teaching hospital during a 2-year period, and the associated microbial and clinical variables were investigated. According to multivariate analysis, Streptococcus pneumoniae, beta-haemolytic streptococci, Escherichia coli, Klebsiella, Enterobacter, Citrobacter and Aeromonas were characterised by fast growth, with an endovascular source, shock, liver cirrhosis and neutropenia also predicting a short time-to-positivity. For patients not receiving appropriate antibiotics, detection of Gram-positive cocci in clusters within 14 h was predictive of Staph. aureus; a time-to-positivity of >21 h ruled out the possibility that a Gram-positive organism in chains was a beta-haemolytic streptococcus or Strep. pneumoniae, and a time-to-positivity of < or =12 h meant that it was very unlikely that a Gram-negative bacillus was a non-fermenter. A time-to-positivity of < or =8 h was predictive of a non-urinary tract source in patients with E. coli bacteraemia, and detection of growth within 13 h predicted an endovascular source in those with Staph. aureus bacteraemia. In conclusion, time-to-positivity depended on the microorganism, original source and clinical variables involved. Although this measurement may provide some early clues concerning the microorganisms involved and the source of bacteraemia, its clinical impact remains to be defined.

Secular trends of blood isolates in patients from a rural area population hospitalized in a tertiary center in a small city in Greece

BACKGROUND

Most of the studies evaluating the secular trends of blood isolates come from tertiary hospitals in urban areas. We sought to study the trends of the antimicrobial resistance of blood isolates in patients from a rural population hospitalized in a tertiary hospital in a small city in Greece.

METHODS

We retrospectively collected and analysed data for the first positive blood culture obtained for each admission for each patient hospitalized in General Hospital of Tripolis, Tripolis, Peloponnesus, Greece during a 5 year period (16/05/2000-15/05/2005).

RESULTS

Sixty-seven thousand and seventy patients were hospitalized during the study period from whom 3,206 blood cultures were obtained. A higher increase of the number of obtained blood cultures than the number of admissions was noted during the study period (p < 0.001). Three hundred and seventy-three (11.6%) blood cultures were positive. Coagulase-negative staphylococci (35.9%), Escherichia coli (29%), and Staphylococcus aureus (18.2%) were the most commonly isolated pathogens. Among the Staphylococcus aureus isolates, the proportion of methicillin-resistant Staphylococcus aureus (MRSA) was 17.2% (5/29). The proportion of Escherichia coli resistant to trimethoprim and sulfamethoxazole, ampicillin and cefuroxime was 29.6% (32/108), 25.0% (27/108), and 8.3% (9/108) respectively. Imipenem-resistance was noted in 3.4% (1/29) of Pseudomonas aeruginosa isolates. There were only 6 (1.6%) Acinetobacter baummanii blood isolates during the study period.

CONCLUSION

The antimicrobial resistance of isolates from patients receiving care at the studied tertiary hospital in a small city in Greece is considerably less compared to that noted in tertiary hospitals in larger cities of the country.