Survey of blood culture isolates in an area of Sweden from 1980 to 1986

Prevalence and Mortality Associated with Bloodstream Organisms: a Population-Wide Retrospective Cohort Study

Bloodstream infections (BSIs) represent a substantial mortality risk, yet most studies are limited to select pathogens or populations. The aim of this study was to describe the population-wide prevalence of BSIs and examine the associated mortality risk for the responsible microorganisms. We conducted a population-wide retrospective cohort study of BSIs in Ontario in 2017. Blood culture data was collected from almost all microbiology laboratories in Ontario and linked to data sets of patient characteristics. For each organism, we determined the prevalence and crude mortality risk, and using logistic regression models, the adjusted odds of 30-day mortality was calculated relative to patients with negative blood cultures and matched patients without blood culture testing. From 531,065 blood cultures, we identified 22,935 positive BSI episodes in 19,326 patients, for an incidence of 150 per 100,000 population. The most frequently isolated organisms were Escherichia coli, Staphylococcus aureus, coagulase-negative staphylococci, Klebsiella species, and Enterococcus species with 40.2, 22.4, 12.1, 11.1, and 7.1 episodes per 100,000 population respectively. BSI episodes were associated with 17.0% mortality at 30 days. Compared to patients with negative cultures, the adjusted 30-day mortality risk for positive BSIs was 1.47 (95% confidence interval (CI), 1.41 to 1.54) and compared to matched patients without blood culture testing was 2.62 (95% CI, 2.52 to 2.73). Clostridium species were associated with the highest adjusted odds of mortality compared to that of negative cultures (adjusted odds ratio, 5.81; 95% CI, 4.00 to 8.44). Among high incidence pathogens, Staphylococcus aureus had the highest odds ratio of mortality (adjusted odds ratio, 2.14; 95% CI, 1.94 to 2.36). BSIs are associated with increased mortality risk, varying across organisms.

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.

Epidemiology of Staphylococcus aureus bacteremia in Denmark from 1957 to 1990

OBJECTIVE: To investigate the changes in epidemiology of Staphylococcus aureus (SA) bacteremia in Denmark over a 30-year period, where the population has remained stable. METHODS: Bacteriologic and clinical data were generated on 17 712 SA strains from virtually all SA bacteremia cases in Denmark from 1957 to 1990 submitted to our laboratory for phage typing. The data were related to information about population, hospital activity and blood-culturing activity during that period. RESULTS: SA bacteremia cases increased from 3 to 20/100 000 inhabitants per year, with the largest increases in incidence rates for the <1-year and >50-year age groups. While blood-culturing activity increased three-fold during the period, the rate of SA bacteremias actually decreased relative to the number of blood cultures taken. The increase in SA bacteremia cases was mainly due to increases in nosocomial infections for all age groups and was related to the increasing admission rates to Danish hospitals. Major shifts in antibiotic resistance patterns and phage types took place during the period, i.e. a marked reduction in multiresistant (including methicillin-resistant) strains, but could not explain the change in the epidemiology of the infections. CONCLUSIONS: The data indicate that increases in SA bacteremia rates correlated significantly with increasing numbers of admissions to hospitals. The main increase in SA bacteremia rates was represented by nosocomial infection, although increasing blood-culturing activity during the period may have contributed.

Evaluation of staphylococci isolated from a blood culture system (Colorbact)

During a one-year period, all blood cultures positive for staphylococci from two of the smaller Danish counties with non-university hospitals only were evaluated. The isolates were speciated and coagulase-negative staphylococci (CoNS) were biotyped. Furthermore, antibiogram, phage typing and lectin typing were performed for all isolates. Clinical information was obtained by telephone, and before any bacteriological identification was performed, a preliminary judgment was made as to whether the positive blood culture was of clinical significance. A total of 3,500 blood cultures were evaluated and 426 (12.2%) were positive. One hundred and sixty blood cultures from 137 patients contained staphylococci; 36 of these patients had a pure culture of Staphylococcus aureus. One hundred and twenty-four CoNS were found and identified as S. epidermidis (81), S. hominis (19), S. haemolyticus (8), S. simulans (1), and Micrococcus species (3), and another 12 staphylococcal isolates which could not be identified to species level. A total of 35 patients had mixed cultures, including 6 with S. aureus as one of the isolates and 15 with mixed CoNS. Clinical relevance was estimated in 90% of cases where the later bacterial identification showed S. aureus, whereas clinical relevance was absent in the majority of cases including CoNS. Methicillin and gentamicin resistance was absent among S. aureus, but frequent among CoNS, especially S. epidermidis, where 40% were resistant to methicillin and 30% to gentamicin.

Survey of bacteraemia in a Spanish hospital over a decade (1981-1990)

The aetiology, epidemiology and in-vitro antibiotic susceptibility of bacteraemic isolates in a Spanish hospital, over a decade (1981-1990), were reviewed. A total of 4363 possible episodes were microbiologically confirmed (incidence: 15.7 cases per 1000 admissions). A slight increase in the number of Gram-positive cocci and anaerobes over the last 4 years was found. The most frequent species (annual range) were: Escherichia coli (13.5%-18.9%), Staphylococcus aureus (10.5%-17.8%), Klebsiella spp. (3.0%-9.4%), Enterococcus faecalis (3.0%-8.2%), Pseudomonas aeruginosa (2.5%-5.8%) and Streptococcus pneumoniae (1.8%-5.6%). Males were more affected than females (ratio 1.7:1). The portal of entry was known in 2126 episodes, of which the most frequent were urinary and gasto-intestinal tracts (24.4% and 19.4% respectively). Bacteraemia was associated with rapidly and ultimately fatal underlying diseases in 7.2% and 15.1% of the cases respectively. The hospital location of patients was: medical ward 46.0%, surgical ward 22.7%, paediatric ward 16.9%, and intensive care unit 14.4%.

Predictors for bacteraemia

In a study of 4104 episodes of septicaemia seen at St Thomas's Hospital between 1969 and 1989, predictors for the condition, other than age and hospital service, were difficult to identify, mainly as a result of the limited data available on the denominator groups. The collection of a small number of simple and readily assessed items of information on all patients with septicaemia did, however, allow the identification of some associations between certain groups of patients and particular species of bacteria and foci of infection. Until there is a substantially larger amount of accurate, complete and computerized data on all hospital patients, further recognition of predictors for bacteraemia will prove difficult to develop.

A 10-year survey of clinically significant blood culture isolates and antibiotic susceptibilities from adult patients with hematological diseases at a major Swedish hospital

In patients treated with cytotoxic drugs granulocytopenia and septicemia are commonly seen. In this 10-year survey 324 blood culture isolates from 184 patients with hematological diseases and septicemia were studied. The distribution of microbiological diagnoses in patients with hematological diseases as well as acute leukemia 1980-1986 was significantly different (p less than 0.01) from an unselected blood culture material from the same period. The differences are mainly seen between Enterobacteriaceae other than Escherichia coli, Pseudomonas aeruginosa and staphylococci. The microbiological spectrum for patients with hematological disease 1987-1989 was also significantly different (p less than 0.05) from the spectrum of the same group of patients 1980-1986 due to higher frequencies of coagulase-negative staphylococci and alpha-streptococci and lower frequency of E. coli in the latter period. 40% of the isolates were gram-positive cocci during the first period and increased to 50% during the second period. The susceptibility testing indicates that trimethoprim/sulfonamide is not as good a choice as ciprofloxacin or norfloxacin for oral antibiotic prophylaxis. For intravenous therapy imipenem/cilastatin or the combinations of an aminoglycoside/piperacillin or aminoglycoside/third generation cephalosporin have advantages over aminoglycoside/trimethoprim/sulfa in combination. However, addition of isoxazolylpenicillin or vancomycin now seems necessary to cover the increasing part of gram-positive bacteria causing septicemia in patients with hematological disease.

Yeasts in blood cultures: impact of early therapy

Patients with growth of yeast in blood cultures were analyzed during the 6-year-period 1981-1986, with special regard to predisposing factors, mortality, severity of the disease and therapy. There were 80 isolations of yeasts in blood cultures in 39 patients and Candida albicans was the most common. The majority of the patients in the material had multiple predisposing factors. The overall mortality was 58%. Patients with d disseminated disease had a mortality of 79% in contrast to 32% in patients with transient fungemia. Disseminated disease was more common in surgical patients. The prognosis of patients treated within 4 days from the onset of septic symptoms was significantly better than that of patients with a later start of therapy. On the basis of these results we emphasize the importance of early empiric therapy.