A 6-month prospective study of hospital-acquired bacteremia in Copenhagen county

Timing of positive blood samples does not differentiate pathogens causing healthcare-associated from community-acquired bloodstream infections in children in England: a linked retrospective cohort study

Paediatricians recognize that using the time-dependent community-acquired vs. hospital-acquired bloodstream infection (BSI) dichotomy to guide empirical treatment no longer distinguishes between causative pathogens due to the emergence of healthcare-associated BSIs. However, paediatric epidemiological evidence of the aetiology of BSIs in relation to hospital admission in England is lacking. For 12 common BSI-causing pathogens in England, timing of laboratory reports of positive paediatric (3 months to 5 years) bacterial blood isolates were linked to in-patient hospital data and plotted in relation to hospital admission. The majority (88·6%) of linked pathogens were isolated <2 days after hospital admission, including pathogens widely regarded as hospital acquired: Enterococcus spp. (67·2%) and Klebsiella spp. (88·9%). Neisseria meningitidis, Streptococcus pneumoniae, group A streptococcus and Salmonella spp. were unlikely to cause hospital-acquired BSI. Pathogens commonly associated with hospital-acquired BSI are being isolated <2 days after hospital admission alongside pathogens commonly associated with community-acquired BSI. We confirm that timing of blood samples alone does not differentiate between bacterial pathogens. Additional factors including clinical patient characteristics and healthcare contact should be considered to help predict the causative pathogen and guide empirical antibiotic therapy.

Community-acquired, healthcare-associated and hospital-acquired bloodstream infection definitions in children: a systematic review demonstrating inconsistent criteria

BACKGROUND

Historically, bacterial infections were categorized as either community-acquired (CA) or hospital-acquired (HA). However, the CA/HA dichotomy no longer adequately reflects patterns of emerging healthcare-associated (HCA) infections in complex patients managed between hospital and the community. Studies trying to define this evolving epidemiology often excluded children.

AIM

To identify what criteria have been used to distinguish between CA, HCA and HA bloodstream infections (BSIs) in children, and the proportional distribution of CA, HCA and HA among total BSIs and by organism.

METHODS

We systematically reviewed published literature from PubMed, UK Department of Health and US Centers for Disease Control and Prevention websites.

FINDINGS

Results from 23 studies and the websites highlighted the use of inconsistent criteria. There were 13 and 15 criteria variations for CA and HA BSI respectively, although a 48h cut-off for cultures sampled post admission was most commonly reported. Five studies used variable clinical criteria to define HCA. The mean proportion of paediatric CA BSI in nine studies was 50%. Only four BSI organisms from five studies were predominantly CA (Streptococcus pneumoniae, Salmonella spp.) or HA (coagulase-negative staphylococci, Enterococcus spp.), whereas Pseudomonas spp., Klebsiella spp. and Enterobacter spp. did not clearly fit into either category.

CONCLUSIONS

Our study reveals inconsistent use of criteria, and a lack of evidence upon which to base them, to distinguish between CA, HCA and HA BSI in children. Criteria for CA, HCA and HA BSI need to be developed using population-based studies that consider patients' clinical characteristics, recent healthcare exposure as well as isolated organism species.

Epidemiology of bacteraemia in Hamad general hospital, Qatar: a one year hospital-based study

We conducted a one-year observational study from July 2007 to June 2008 to describe the epidemiology of bacteraemia at Hamad general hospital. During this period, a total of 452 episodes of bacteraemia occurred, which corresponds to a rate of 19/1000 hospital admissions. Most patients 58.8% (266/452) had community acquired bacteraemia, and primary bacteraemia accounted for 62.2% (281/452) of the cases. The most common source of bacteraemia was intravenous catheterization in 19.2% (87/452) but no source was identified in 42.9% (194/452) of the episodes. Gram-negative organisms were isolated in 63.1% (285/452) episodes with Escherichia coli being the most frequent 21.5% (97/452). Multidrug resistance was observed in 33.3% (7/21) of all Pseudomonas aeruginosa isolates, 50% (6/12) of Acinetobacter isolates and 28.6% (6/21) of Enterobacter isolates, whereas all ESBL producing Klebsiella spp. and E. coli were multiresistant. The percentages of oxacillin resistant coagulase negative Staphylococci isolates and methicillin-resistant Staphylococcus aureus isolates were 81.8% (27/33) and 13.2% (7/53) respectively. In hospital mortality was 22.5% (102/452), and inadequate treatment and septic shock were found to be independent predictors of mortality. Therefore, bloodstream infection surveillance is crucial to produce meaningful guidelines for prevention (e.g., catheter-related) and empirical treatment of bacteraemia in Qatar.

Course and outcome of Staphylococcus aureus bacteraemia: a retrospective analysis of 308 episodes in a Swiss tertiary-care centre

Staphylococcus aureus bacteraemia (SAB) is associated with substantial morbidity and mortality worldwide. The charts of adult patients with SAB who were hospitalised in a Swiss tertiary-care centre between 1998 and 2002 were studied retrospectively. In total, 308 episodes of SAB were included: 2% were caused by methicillin-resistant strains; 49% were community-acquired; and 51% were nosocomial. Bacteraemia without focus was the most common type of community-acquired SAB (52%), whereas intravenous catheter-related infection predominated (61%) among nosocomial episodes of SAB. An infectious diseases (ID) specialist was consulted in 82% of all cases; 83% received appropriate antibiotic treatment within 24 h of obtaining blood cultures. Overall hospital-associated mortality was 20%. Community-acquired SAB was associated independently with a higher mortality rate than nosocomial SAB (26% vs. 13%; p 0.009). Independent risk-factors for a fatal outcome were age (p < 0.001), immunosuppression (p 0.007), alcoholism (p < 0.001), haemodialysis (p 0.03), acute renal failure (p < 0.001) and septic shock (p < 0.001). Consultation with an ID specialist was associated with a better outcome in univariate analysis (p < 0.001). Compared with a previous retrospective analysis performed at the same institution between 1980 and 1986, there was a 140% increase in community-acquired SAB, a 60% increase in catheter-related SAB, and a 14% reduction in mortality. In conclusion, mortality in patients with SAB remained high, despite effective antibiotic therapy. Patients with community-acquired SAB were twice as likely to die as patients with nosocomial SAB. Consultation with an ID specialist may reduce mortality in patients with SAB.

Are Antimicrobial-Impregnated Catheters Effective? Replace the Water and Grab Your Washcloth, Because We Have a Baby to Wash

Significant controversy surrounds the usefulness of central venous catheters (CVCs) impregnated with antimicrobial agents (A-CVCs) for the prevention of catheter-related bloodstream infections (CRBSIs). In a recent issue of Clinical Infectious Diseases, we reviewed 11 published trials of A-CVCs versus uncoated CVCs, and we concluded that there is a lack of solid evidence to support a benefit of A-CVCs in reducing the rate of CRBSIs. A response to our review was recently published in Clinical Infectious Diseases. In this response, our colleagues assert that there is a large body of evidence that demonstrates a powerful decrease in the risk of infection, and they conclude that we should not waste precious resources while we perform additional research to confirm what we have already found to be true. Although these authors agree with us on the significant shortcomings of the studies used to support the use of A-CVCs, they dismiss the need for additional trials to demonstrate that the use of A-CVCs does reduce infections. This dismissal, however, cannot be justified, because of the existence of an ongoing, federally supported, multicenter, prospective, placebo-controlled trial, led by our colleagues, that compares the rate of CRBSIs among patients randomized to receive either an A-CVC or a "placebo" uncoated CVC. That our colleagues are leading a trial that assesses the efficacy of A-CVCs versus placebo uncoated CVCs supports our viewpoint that the truth regarding the protective role of A-CVCs has yet to be determined. Because of the significant cost, potential toxicity, and risk of increased antimicrobial resistance associated with the use of A-CVCs, and until the results of the important trial conducted by our colleagues convincingly demonstrate that A-CVCs reduce the rate of clinically significant events (not just catheter colonization), we recommend that the use of A-CVCs be limited to investigational settings.

Bilateral endogenous bacterial endophthalmitis: a report of four cases

PURPOSE

To present and discuss four cases of bilateral endogenous endophthalmitis.

METHODS

An observational study of four patients aged 55-80 years, seen within a 2-year period. All had diagnostic and therapeutic vitrectomy. The antibiotic therapy was guided by analyses of cultures of blood and vitreous.

RESULTS

Blood cultures demonstrated Streptococcus pneumoniae in two patients and Staphylococcus aureus and Morganella morganii, each in one patient. The findings corresponded with culture findings from vitreous material in two patients. The primary foci for the metastatic spread of infection were endocarditis, discitis and a subdural abscess of the lumbar spine, urinary tract infection, and infection of a recent hip alloplasty, respectively, in the four patients. Five eyes became blind, whereas three eyes recovered to visual acuity of 0.25-0.67.

CONCLUSIONS

Endogenous bacterial endophthalmitis usually leads to total loss of vision. The disease is acute and the time span for intervention limited. We believe that an active therapeutic approach including intravitreal antibiotics and vitreoretinal surgery saved three eyes from blindness.

Mucosa or skin as source of coagulase-negative staphylococcal bacteraemia?

Nosocomial bacteraemia is associated with significant morbidity, mortality, and cost worldwide, and is most commonly caused by coagulase-negative staphylococci (CONS). Establishing the source of CONS bacteraemia is therefore important in the prevention and management of this infection. CONS infections are presumed to originate at the cutaneous sites of central venous catheters (CVCs), a belief that has led to prevention strategies that focus almost exclusively on the skin. However, mucosal colonisation by CONS is well established, suggesting that mucosal sites might be an important source of CONS bacteraemia. We review the published material that evaluates the source(s) of CONS. We included only studies that used a strict definition of CONS bacteraemia, evaluated skin and other potential sources of CONS, and studied the molecular association between CONS blood isolates and their potential sources. Three published reports fulfilled our criteria. In cancer patients with CONS or CONS bacteraemia, most of the colonising strains that had a molecular match with the strain recovered from the blood of the same patient were mucosal isolates; by contrast, no association was seen between CONS blood and skin isolates. Furthermore, in several patient populations evidence was reported of mucosal colonisation by CONS and in several reports experimental and clinical mucosal translocation of CONS with subsequent bacteraemia was documented. Together these data indicate that mucosal sites are an important source of CONS bacteraemia. Clinical strategies for the treatment of patients with a positive blood culture for CONS, the widespread use of antimicrobial-coated CVCs, and maximum barrier protection for CVC insertion should be reassessed, and strategies to decrease mucosal colonisation by CONS should be developed.

Do antimicrobial-impregnated central venous catheters prevent catheter-related bloodstream infection?

Controversy surrounds the role of central venous catheters (CVCs) impregnated with antimicrobial agents in the prevention of catheter-related bloodstream infection (CRBSI). We reviewed the current literature to evaluate the efficacy of antimicrobial-impregnated CVCs for preventing CRBSI. Eleven randomized studies published in article form were identified that included a control group that received nonimpregnated CVCs. We evaluated study methodologies, inclusion of key patient characteristics, use of clinically relevant end points, and molecular-relatedness studies. Review of these 11 trials revealed several methodological flaws, including inconsistent definitions of CRBSI, failure to account for confounding variables, suboptimal statistical and epidemiological methods, and rare use of clinically relevant end points. This review also failed to demonstrate any significant clinical benefit associated with the use of antimicrobial-impregnated CVCs for the purpose of reducing CRBSI or improving patient outcomes. More rigorous studies are required to support or refute the hypothesis that antimicrobial-impregnated CVCs reduce the rate of or prevent CRBSI.

Reappraisal of community-acquired bacteremia: a proposal of a new classification for the spectrum of acquisition of bacteremia

In recent years, dramatic changes in health care systems have shifted much of the care of sick individuals from hospitals to the community. Consequently, infections traditionally classified as community-acquired or hospital-acquired infections cannot now be readily classified into either category. We thus propose a new classification based on a wider spectrum of acquisition. A total of 1028 episodes of bloodstream infection (BSI) were divided into 5 categories: true community-acquired infections (370 episodes [36%]), infections in recently discharged patients (110 [11%]), infections associated with invasive procedures performed just before or at the time of admission (56 [5%]), infections in patients admitted from nursing homes (68 [7%]), and hospital-acquired infections (424 [41%]). Thus, 234 (39%) of the 604 bloodstream infections traditionally defined as community acquired were reclassified into 3 newly defined groups, each of which has distinct epidemiologic, clinical, and bacteriologic characteristics, as well as distinct antimicrobial susceptibility profiles. There is a conceptual and practical need for such a new classification.

High antibiotic consumption in Danish intensive care units?

Decreased antibiotic susceptibility among microorganisms isolated from intensive care unit (ICU) patients is found to be associated with high total antibiotic consumption or inappropriate use of antibiotics in the ICUs. The aims of this study were: 1) to characterize the antibiotic consumption in Danish ICUs, and in four ICUs with expectedly large differences in levels of antibiotic consumption, 2) to estimate the association between antibiotic susceptibility among isolated microorganisms and antibiotic consumption. This was done by: 1) a retrospective questionnaire study of the annual supply of antibiotics in 1995 to 30 ICUs in Denmark, and 2) a 2-month prospective study of patients and microbiological samples in four Danish ICUs in 1996. We found that the supply of antibiotics to Danish ICUs was substantial, with a median value of 124 DDD/100 patient days. No association was found between high consumption of antibiotics and decreased antibiotic susceptibility in the four ICUs.