Vancomycin-resistant Enterococcus faecium: impact of ending screening and isolation in a Danish University hospital.

BACKGROUND: Substantial resources are used in hospitals worldwide to counteract the ever-increasing incidence of vancomycin-resistant and vancomycin-variable Enterococcus faecium (VREfm and VVEfm), but it is important to balance patient safety, infection prevention, and hospital costs. AIM: To investigate the impact of ending VREfm/VVEfm screening and isolation at Odense University Hospital (OUH), Denmark, on patient and clinical characteristics, risk of bacteraemia, and mortality of VREfm/VVEfm disease at OUH. The burden of VREfm/VVEfm bacteraemia at OUH and the three collaborative hospitals in the Region of Southern Denmark (RSD) was also investigated. METHODS: A retrospective cohort study was conducted including first-time VREfm/VVEfm clinical isolates (index isolates) detected at OUH and collaborative hospitals in the period 2015-2022. The intervention period with screening and isolation was from 2015 to 2021, and the post-intervention period was 2022. Information about clinical isolates was retrieved from microbiological databases. Patient data were obtained from hospital records. FINDINGS: At OUH, 436 patients were included in the study, with 285 in the intervention period and 151 in the post-intervention period. Ending screening and isolation was followed by an increased number of index isolates. Besides a change in van genes, only minor non-significant changes were detected in all the other investigated parameters. Mortality within 30 days did not reflect the VREfm/VVEfm-attributable deaths, and in only four cases was VREfm/VVEfm infection the likely cause of death. CONCLUSION: Despite an increasing number of index isolates, nothing in the short follow-up period supported a reintroduction of screening and isolation.

C-reactive protein and albumin kinetics before community-acquired bloodstream infections - a Danish population-based cohort study.

Early changes in biomarker levels probably occur before bloodstream infection (BSI) is diagnosed. However, this issue has not been fully addressed. We aimed at evaluating the kinetics of C-reactive protein (CRP) and plasma albumin (PA) in the 30 days before community-acquired (CA) BSI diagnosis. From a population-based BSI database we identified 658 patients with at least one measurement of CRP or PA from day -30 (D-30) through day -1 (D-1) before the day of CA-BSI (D0) and a measurement of the same biomarker at D0 or D1. Amongst these, 502 had both CRP and PA measurements which fitted these criteria. CRP and PA concentrations began to change inversely some days before CA-BSI diagnosis, CRP increasing by day -3.1 and PA decreasing by day -1.3. From D-30 to D-4, CRP kinetics (expressed as slopes - rate of concentration change per day) was -1.5 mg/l/day. From D-3 to D1, the CRP slope increased to 36.3 mg/l/day. For albumin, the slope between D-30 to D-2 was 0.1 g/l/day and changed to -1.8 g/l/day between D-1 and D1. We showed that biomarker levels begin to change some days before the CA-BSI diagnosis, CRP 3.1 days and PA 1.3 days before.

Hypoalbuminaemia as a marker of trans-capillary leakage in community-acquired bacteraemia patients.

Community-acquired bacteraemia patients (n = 2472), Denmark, 2000-2008. Albumin, C-reactive protein (CRP) and haemoglobin (Hb) measured 2000-2010. We assessed daily mean levels of albumin, CRP and Hb from 30 days before to 30 days after bacteraemia and correlations between albumin vs. CRP and albumin vs. Hb. In linear regression models, we evaluated the contribution of CRP, Hb, chronic and acute variables to the albumin level variations. The mean albumin level (33.6 g/l) was steady before day 1, declined to 29.3 g/l on day 1 with little increase afterward. The mean CRP increased from day -5, peaked on day 1 and declined thereafter. The mean Hb level was fairly constant during days -30/30. Albumin was inversely (R range, - 0.18/-0.47, P < 10-4) correlated with the CRP level and positively (R = 0.17-0.46, P < 10-4) correlated with the HB level. In most models, CRP was the first variable that contributed to the albumin variations, 34-70% of the full model. The sudden decrease of albumin levels, without sudden fluctuations of CRP or Hb, indicated that hypoalbuminaemia was a marker of trans-capillary leakage.

Antibiotic treatment and mortality in patients with Listeria monocytogenes meningitis or bacteraemia.

Invasive Listeria monocytogenes infections carry a high mortality despite antibiotic treatment. The rareness of the infection makes it difficult to improve antibiotic treatment through randomized clinical trials. This observational study investigated clinical features and outcome of invasive L. monocytogenes infections including the efficacy of empiric and definitive antibiotic therapies. Demographic, clinical and biochemical findings, antibiotic treatment and 30-day mortality for all episodes of L. monocytogenes bacteraemia and/or meningitis were collected by retrospective medical record review in the North Denmark Region and the Capital Region of Denmark (17 hospitals) from 1997 to 2012. Risk factors for 30-day all-cause mortality were assessed by logistic regression. The study comprised 229 patients (median age: 71 years), 172 patients had bacteraemia, 24 patients had meningitis and 33 patients had both. Significant risk factors for 30-day mortality were septic shock (OR 3.0, 95% CI 1.4-6.4), altered mental state (OR 3.6, 95% CI 1.7-7.6) and inadequate empiric antibiotic therapy (OR 3.8, 95% CI 1.8-8.1). Cephalosporins accounted for 90% of inadequately treated cases. Adequate definitive antibiotic treatment was administered to 195 patients who survived the early period (benzylpenicillin 72, aminopenicillin 84, meropenem 28, sulfamethoxazole/trimethoprim 6, and piperacillin/tazobactam 5). Definitive antibiotic treatment with benzylpenicillin or aminopenicillin resulted in a lower 30-day mortality in an adjusted analysis compared with meropenem (OR 0.3; 95% CI 0.1-0.8). In conclusion, inadequate empiric antibiotic therapy and definitive therapy with meropenem were both associated with significantly higher 30-day mortality.

Decreasing incidence rates of bacteremia: a 9-year population-based study.

BACKGROUND: Numerous studies have shown that the incidence rate of bacteremia has been increasing over time. However, few studies have distinguished between community-acquired, healthcare-associated and nosocomial bacteremia. METHODS: We conducted a population-based study among adults with first-time bacteremia in Funen County, Denmark, during 2000-2008 (N = 7786). We reported mean and annual incidence rates (per 100,000 person-years), overall and by place of acquisition. Trends were estimated using a Poisson regression model. RESULTS: The overall incidence rate was 215.7, including 99.0 for community-acquired, 50.0 for healthcare-associated and 66.7 for nosocomial bacteremia. During 2000-2008, the overall incidence rate decreased by 23.3% from 254.1 to 198.8 (3.3% annually, p < .001), the incidence rate of community-acquired bacteremia decreased by 25.6% from 119.0 to 93.8 (3.7% annually, p < .001) and the incidence rate of nosocomial bacteremia decreased by 28.9% from 82.2 to 56.0 (4.2% annually, p < .001). The incidence rate of healthcare-associated bacteremia remained stable. The most common microorganisms were Escherichia coli (28.3%), Staphylococcus aureus (12.3%), coagulase-negative staphylococci (10.0%) and Streptococcus pneumoniae (9.1%). Regardless of place of acquisition, the proportion of bacteremias caused by enterococci increased (p < .05) and the proportion caused by coagulase-negative staphylococci decreased (p < .05). CONCLUSIONS: The incidence rates of community-acquired and nosocomial bacteremia decreased substantially over time.

Incidence, clinical characteristics and 30-day mortality of enterococcal bacteraemia in Denmark 2006-2009: a population-based cohort study.

Enterococci currently account for approximately 10% of all bacteraemias, reflecting remarkable changes in their epidemiology. However, population-based data of enterococcal bacteraemia are scarce. A population-based cohort study comprised all patients with a first episode of Enterococcus faecalis or Enterococcus faecium bacteraemia in two Danish regions during 2006-2009. We used data collected prospectively during clinical microbiological counselling and hospital registry data. We determined the incidence of mono- and polymicrobial bacteraemia and assessed clinical and microbiological characteristics as predictors of 30-day mortality in monomicrobial bacteraemia by logistic regression analysis. We identified 1145 bacteraemic patients, 700 (61%) of whom had monomicrobial bacteraemia. The incidence was 19.6/100 000 person-years (13.0/100 000 person-years for E. faecalis and 6.6/100 000 person-years for E. faecium). The majority of bacteraemias were hospital-acquired (E. faecalis, 45.7%; E. faecium, 85.2%). Urinary tract and intra-abdominal infections were the predominant foci for the two species, respectively. Infective endocarditis (IE) accounted for 25% of patients with community-acquired E. faecalis bacteraemia. Thirty-day mortality was 21.4% in patients with E. faecalis and 34.6% in patients with E. faecium. Predictors of 30-day mortality included age, co-morbidity and hospital-acquired bacteraemia. In addition, intra-abdominal infection, unknown focus and high-level gentamicin resistance were predictors of mortality in E. faecalis patients. E. faecium was associated with increased risk of mortality compared with E. faecalis. The study emphasizes the importance of enterococci both in terms of incidence and prognosis. The frequency of IE in patients with E. faecalis bacteraemia emphasizes the importance of echocardiography, especially in community-acquired cases.

Pre-operative use of anti-TNF-α agents and the risk of post-operative complications in patients with Crohn's disease--a nationwide cohort study.

BACKGROUND: A possible negative role of pre-operative use of antitumour necrosis factor-alpha (anti-TNF-α) agents on post-operative outcomes in Crohn's disease (CD) patients is still debated. AIM: To examine the impact of pre-operative anti-TNF-α agents on post-operative outcomes 30 and 60 days after CD surgery in a nationwide Danish cohort. Outcomes were death, reoperation, anastomosis leakage, intra-abdominal abscess and bacteraemia. METHODS: We identified all patients having surgical procedures from 1 January 2000 to 31 December 2010 (n = 2293). Patients were classified according to use of anti-TNF-α agents within 12 weeks before surgery (exposed) or not (unexposed). Outcomes were obtained from nationwide registries and a bacteraemia registry. Sub-analyses were performed for bacteraemia and for impact of pre-operative timing of anti-TNF-α agents. RESULTS: Among surgical procedures for CD, 214 were exposed and 2079 were not. We found no increased relative risks of death or abscess drainage 30 or 60 days after follow-up. Among exposed, 7.5% had a reoperation within 30 days vs. 8.6% among unexposed, adjusted odds ratio (OR) = 0.92, 95% confidence interval (CI): 0.52-1.63. Among exposed, 3.8% had an anastomosis leakage within 30 days after surgery vs. 2.8% among unexposed, adjusted OR = 1.33, 95% CI: 0.59-3.02. No further cases of anastomosis leakages appeared within 60 days. Sub-analyses indicated no increased risk of bacteraemia after 30 days and no increased risks when anti-TNF-α agents were given ≤14 days before surgery. CONCLUSION: We found no significantly increased relative risks of post-operative complications after use of anti-TNF-α agents either 12 weeks or ≤14 days before surgery for Crohn's disease.

Pre-operative use of anti-TNF-α agents and the risk of post-operative complications in patients with ulcerative colitis - a nationwide cohort study.

BACKGROUND: It is still controversial whether pre-operative anti-tumour necrosis factor-alpha (anti-TNF-α) agents increase post-operative complications in patients with ulcerative colitis (UC). AIM: In a nationwide Danish cohort of patients with UC, we aimed to examine the impact of pre-operative use of anti-TNF-α agents on post-operative adverse outcomes after colectomy for UC. Outcomes (within 30 and 60 days after surgery) were reoperation, anastomosis leakage, intra-abdominal abscess, bacteremia and death. METHODS: Based on the Danish National Patient Registry we identified all UC patients, aged ≥15 years, having their first surgery for UC in the period of 1 January 2003-31 December 2010 (n = 1226). Patients were classified according to use of anti-TNF-α agents within 12 weeks before surgery or not. Outcome data were obtained from Danish registries. Logistic regression analyses were used to estimate adjusted risks [with 95% confidence intervals (CI)] of post-operative outcomes among patients treated with anti-TNF-α agents, relative to those not treated. RESULTS: A total of 199 UC patients were exposed to anti-TNF-α agents within 12 weeks before colectomy, and 1027 were not. Among exposed, the adjusted odds ratio of reoperation and anastomosis leakage within 30 days after colectomy was 1.07 (95% CI: 0.71-1.59) and 0.52 (95% CI: 0.06-4.11) respectively. No deaths, cases of abscess drainage or bacteremia occurred among exposed within 30 days. Furthermore, no increased relative risks were found within 60 days after colectomy. CONCLUSIONS: Based on nationwide data on UC patients having colectomies, pre-operative use of anti-TNF-α agents did not increase the risk of post-operative complications.

Baseline C-reactive protein level as a predictor of mortality in bacteraemia patients: a population-based cohort study.

We examined the association between C-reactive protein (CRP) level at time of blood culture (BC) draw and mortality following bacteraemia. Our population-based cohort study comprised all first-time monomicrobial bacteraemia episodes in adults in a Danish county during 1996-2004 (n = 5267). CRP was measured within 24 h of the first positive BC draw. Cox regression was used to compute mortality rate ratios (MRRs) associated with CRP level quartiles (10-64 (reference), 65-143, 144-240 and 241-688 mg/L), controlling for age, gender, comorbidity, specialty, acquisition of infection, and infection focus. We also looked for a biological interaction between CRP level and high magnitude of bacteraemia (three of three culture bottles positive). Thirty-day mortality increased with higher CRP level: adjusted 0-30-day MRRs for patients in the second, third and fourth CRP quartiles were 1.38 (95% CI 1.13-1.69), 1.70 (95% CI 1.40-2.06), and 2.38 (95% CI 1.96-2.87), respectively (p for trend <10(-4)). In contrast, mortality associations with CRP during 31-365 days of follow-up were weak (adjusted MRRs for the second to fourth quartiles ranged from 1.18 to 1.28). A high magnitude of bacteraemia strengthened the association between high CRP level and 30-day mortality. We conclude that the CRP level, measured concurrently with the first positive BC, independently predicted 30-day mortality in adult bacteraemia patients.

Bacteraemia as a result of Campylobacter species: a population-based study of epidemiology and clinical risk factors.

Invasive disease as a result of Campylobacter is rarely reported. We reviewed 46 cases of blood stream infection with Campylobacter in a Danish population with complete follow-up. The incidence was 2.9 per 1 million person-years with a peak incidence in the age group above 80 years. In the population, the ratio of notified bacteraemia/enteritis patients with Campylobacter infection was 0.004. Patients with bacteraemia were older and had higher comorbidity, e.g. alcoholism, immunosuppression, previous gastrointestinal surgery or HIV infection. We found 26% of blood isolates resistant to ciprofloxacin. The length of hospitalization was significantly longer in bacteraemia patients, whereas the outcome was favourable with 28-day mortality of 4% in bacteraemia patients and 1% in enteritis patients. None of the bacteraemia patients relapsed within 365-day follow-up.

Magnitude of bacteraemia is a predictor of mortality during 1 year of follow-up.

We evaluated magnitude of bacteraemia as a predictor of mortality, comprising all adult patients with a first-time mono-microbial bacteraemia. The number of positive bottles [1 (reference), 2, or 3] in the first positive blood culture (BC) was an index of magnitude of bacteraemia. We used Cox's regression analysis to determine age and comorbidity adjusted risk of mortality at days 0-7, 8-30, and 31-365. Of 6406 patients, 31.1% had BC index 1 (BCI 1), 18.3% BCI 2, and 50.6% BCI 3. BCI 3 patients had increased risk of mortality for days 0-7 (1.30, 95% CI 1.10-1.55) and days 8-30 (1.37, 95% CI 1.12-1.68), but not thereafter. However, in surgical patients mortality increased only beyond day 7 (8-30 days: 2.04, 95% CI 1.25-3.33; 31-365 days: 1.27, 95% CI 0.98-1.65). Thus, high magnitude of bacteraemia predicted mortality during the first month with a shift towards long-term mortality in surgical patients.

Severity of infection and seasonal variation of non-typhoid Salmonella occurrence in humans.

Non-typhoid Salmonella infections may present as severe gastroenteritis necessitating hospitalization and some patients become septic with bacteraemia. We hypothesized that the seasonal variation of non-typhoid Salmonella occurrence in humans diminishes with increased severity of infection. We examined the seasonal variation of non-typhoid Salmonella infections in three patient groups with differing severity of infection: outpatients treated for gastroenteritis (n=1490); in-patients treated for gastroenteritis (n=492); and in-patients treated for bacteraemia (n=113). The study was population-based and included all non-typhoid Salmonella patients in a Danish county from 1994 to 2003. A periodic regression model was used to compute the peak-to-trough ratio for the three patient groups. The peak-to-trough ratios were 4.3 [95% confidence interval (CI) 3.6-5.0] for outpatients with gastroenteritis, 3.2 (95% CI 2.4-4.2) for in-patients with gastroenteritis, and 1.6 (95% CI 1.0-2.8) for in-patients with bacteraemia. We conclude that the role of seasonal variation diminishes with increased severity of non-typhoid Salmonella infection.

High incidence of intravascular focus in nontyphoid Salmonella bacteremia in the age group above 50 years: a population-based study.

Questions regarding the relative frequency of vascular complications in nontyphoid Salmonella bacteremia are pending, and the true population-based age-related incidence is not known. We reviewed all cases of nontyphoid Salmonella bacteremia during a 10-year period from 1994 through 2003 in a well-defined population of 492,843 residents in North Jutland County, Denmark. 77 of a total of 111 cases occurred in patients >50 years old. In this age group, five cases of mycotic aneurysm and two cases of endocarditis were documented, corresponding to a 9% occurrence. The annual incidence rate of endovascular nontyphoid Salmonella infection in this age group was 4.4 per 1,000,000 person years. The mortality was 43% in cases with endovascular infection, and surgical procedures were important for survival. We conclude that in patients older than 50 years, detection of nontyphoid Salmonella bloodstream infection should be followed by examinations for mycotic aneurysms and endocarditis.

Incidence and prognosis of non-typhoid Salmonella bacteraemia in Denmark: a 10-year county-based follow-up study.

The aim of this study was to examine the incidence and prognosis of non-typhoid Salmonella bacteraemia in a well-defined population in which complete follow-up investigations had been performed. All patients with non-typhoid Salmonella bacteraemia from 1994 through 2003 in North Jutland County, Denmark, were eligible for the study. Annual incidence rates were calculated for 10-year age groups. The North Jutland County Bacteraemia Database (inclusion of subjects), medical hospital records, the Prescription Registry (redemption of prescription drugs), and the Central Population Registry (deaths) were used as data sources. The outcomes were mortality within 30 and 180 days of the first non-typhoid-Salmonella-positive blood sample. Cox proportional-hazards regression analysis was performed, first with age and comorbidity as evidenced by Charlson index scores, and second with selected clinical and laboratory prognostic variables potentially related to non-typhoid Salmonella bacteraemia per se. A total of 111 non-typhoid Salmonella bacteraemia patients were included in the study. The incidence rate (mean 2.3/100,000 person-years) increased steadily from 1.9/100,000 person-years in the 40-49-year age group to 14.6/100,000 person-years in those >90 years. Twelve (11%) and 24 (22%) patients died within 30 and 180 days, respectively. Cox regression analyses showed that increasing age and, to a higher degree, increasing levels of comorbidity were independently associated with an unfavourable outcome, whereas none of the clinical or laboratory variables studied were strong independent prognostic factors. In conclusion, the presence of comorbid diseases and old age were independently associated with mortality, whereas clinical and laboratory variables were less important.

Farm disinfectants select for cyclohexane resistance, a marker of multiple antibiotic resistance, in Escherichia coli.

AIMS: The aim of this study was to determine if three classes of farm disinfectants were able to select for ciprofloxacin or cyclohexane tolerant [indicative of a multiple antibiotic resistance (MAR) phenotype] Escherichia coli and if cyclohexane-tolerant E. coli could be isolated from farms. METHODS AND RESULTS: Chicken slurry containing ca 1 : 99 ratio ciprofloxacin resistant : susceptible E. coli (10 different resistant strains examined) was treated for 24 h with each of the disinfectants and examined for survival of resistant : susceptible strains. Ciprofloxacin-sensitive (n=5) and -resistant (n=5) E. coli were grown with sublethal concentrations of the disinfectants and then plated to agar containing ciprofloxacin or overlaid with cyclohexane. Escherichia coli (n=389) isolated from farms were tested for cyclohexane tolerance. Minimum inhibitory concentrations (MIC) were determined against representative isolates and mutants. The disinfectants did not select for the ciprofloxacin-resistant E. coli in poultry slurry but following growth with each of the three disinfectants, higher numbers (P < or = 0.023) of cyclohexane-tolerant E. coli were isolated and these had a MAR phenotype. Of the 389 farm E. coli tested, only one was cyclohexane tolerant. CONCLUSIONS: It is possible that in a farm environment, E. coli could be exposed to similar concentrations of the disinfectants that are selected for MAR type organisms under these laboratory conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Data from this study suggest that cyclohexane-resistant E. coli are not common on farms, but in view of the ease of isolating them in the laboratory with farm disinfectants, further investigations on farms are warranted.

Surface disinfection tests with Salmonella and a putative indicator bacterium, mimicking worst-case scenarios in poultry houses.

Surface disinfection studies mimicking worst-case scenarios in badly cleaned poultry houses were made with 3 bacterial isolates (Salmonella enteritidis, Salmonella senftenberg, and Enterococcus faecalis), and 3 1% disinfectant solutions, formaldehyde (F; 24.5% vol/vol), glutaraldehyde/benzalkonium chloride (G; Bio Komplet Plus), and a peroxygen compound (P; Virkon S), with World Health Organization (WHO) standard hard water as a control. Materials (concrete paving stones, steel feed chain links, wooden dowels, and jute egg belts) and organic matter found commonly in poultry houses (feed, fats, egg yolk) were used in the tests. Organic matter inoculated with high numbers of stationary phase cultures was added to materials and dried for 24 h at different temperatures (6, 11, 20, or 30 degrees C), immersed in solutions for set time periods (5, 15, or 30 min), and dried again for 25 h (6, 11, or 30 degrees C). Then, traditional recovery procedures (using 10-fold dilutions until 10(-4), i.e., a most probable number method) were applied. For the 2 Salmonella isolates, the efficacy of the solutions was (in decreasing order): formaldehyde > glutaraldehyde/benzalkonium chloride > peroxygen compound > WHO hard water, except when feed chain links with fats were disinfected using 30 degrees C before and after disinfection, for which the peroxygen compound seemed more effective. Enterococcus faecalis was equally or less susceptible than S. enteritidis and S. senftenberg, indicating its suitability as an indicator bacterium. For the peroxygen compound, S. senftenberg was more susceptible than S. enteritidis in spite of higher minimum inhibitory concentrations to this disinfectant for the former.

Monitoring the efficacy of steam and formaldehyde treatment of naturally Salmonella-infected layer houses.

AIMS: To monitor if a temperature-humidity-time treatment found to be effective in eliminating Salmonella in laboratory trials (Gradel et al. 2003) was efficient against Salmonella in naturally infected layer houses. METHODS AND RESULTS: Six layer houses with natural Salmonella infections were steam treated in a download period, aiming at >or=60 degrees C and 100% relative humidity (RH) during a 24-h period, with or without the addition of 30 ppm formaldehyde. In addition, two control layer houses were disinfected chemically. Salmonella samples taken from predetermined sites before and after treatment were tested qualitatively for Salmonella and coliforms. Samples with indicator bacteria (feed inoculated with Escherichia coli or Enterococcus faecalis and faeces with naturally occurring E. coli and enterococci) were placed during steam-treatment at 12 sites in each house (where the temperature was logged at 5-min intervals) and tested for surviving bacteria. Generally, the field test results confirmed the results of laboratory tests, especially when 30 ppm formaldehyde was added to the steam. In well-sealed houses, the recommended temperature-humidity-time scheme was accomplished at a minimum of 10 cm above floor level within 1 h. CONCLUSIONS: A steam treatment of >or=60 degrees C and 100% RH during a 24-h period with the addition of 30 ppm formaldehyde at the beginning of the process is recommended for eliminating Salmonella from naturally infected poultry layer houses. SIGNIFICANCE AND IMPACT OF THE STUDY: A specific recommendation for the elimination of Salmonella in poultry houses can be given.

Laboratory heating studies with Salmonella spp. and Escherichia coli in organic matter, with a view to decontamination of poultry houses.

AIMS: To determine a temperature-humidity-time treatment that eliminates Salmonella and Escherichia coli in substrates representing organic matter in poorly cleaned poultry houses, i.e. worst case scenario laboratory tests. METHODS AND RESULTS: Organic matter (poultry faeces and feed) in a 2.5-cm layer was inoculated with 2 x 10(5)-3 x 10(6) Salmonella g(-1), left undried or dried at ca. 30% relative humidity (RH) during a 10-day period, and temperature increased at 1 degrees C h(-)1 to the final heating temperature of 50, 55, 60, 65 or 70 degrees C and held at 16-30 or 100% RH. All samples were tested for Salmonella according to predetermined sampling time schedules and faecal samples were also tested for naturally occurring E. coli. Overall, humidity was an important factor in the elimination of Salmonella and E. coli. Results for recovery of Salmonella and E. coli were highly associated. CONCLUSIONS: The application of >/=60 degrees C and 100% RH during a 24-h period eliminated Salmonella and E. coli in all samples. Escherichia coli could be used as an indicator bacterium for the elimination of Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: The results from worst case scenario laboratory tests could be applied in steam heating of persistently Salmonella-infected poultry houses. The use of E. coli as an indicator bacterium for the validation of Salmonella results should be considered.

Comparisons of sampling procedures and time of sampling for the detection of Salmonella in Danish infected chicken flocks raised in floor systems.

Bacteriological follow-up samples were taken from 41 chicken (Gallus gallus) flocks in floor systems, where Salmonella enterica (Salmonella) had been detected either directly in bacteriological samples or indirectly by serological samples. Three types of follow-up samples were compared to each other within each flock: 1) 5 pairs of socks, analysed as 5 samples, 2) 2 pairs of socks, analysed as one sample, and 3) 60 faecal samples, analysed as one pooled sample. Agreement between sampling methods was evaluated by the following statistical tests: 'Kappa', 'The adjusted rand', McNemar's test for marginal symmetry, Proportion of agreement P0, P+, P-, and Odds Ratio. The highest agreement was found between the 2 types of sock sampling, while the lowest agreement was found by comparing 60 faecal samples with 5 pairs of socks. Two pairs of socks analysed as one pool appeared to be just as effective in detecting S. enterica as the 60 faecal samples. In broiler flocks, 5 pairs of socks were used both in the routine samples taken at about 3 weeks of age for the establishment of infection of the flock, and as one of the follow-up samples taken shortly before slaughter age, which means that the only notable differences between the 2 sampling rounds were the age of the broilers and of their litter. S. enterica was detected more frequently in samples from broilers about 3 weeks old, than in similar samples taken from broilers a few days prior to slaughter at ca. 33-40 days of age.

Pre-harvest surveillance of Campylobacter and Salmonella in Danish broiler flocks: a 2-year study.

In national surveillance programmes of broiler flocks carried out in Denmark during 1998 and 1999, 89,110 samples for Campylobacter representing 8911 broiler flocks were taken at 10 different abattoirs, and 44,550 samples for Salmonella were taken from the same flocks in the broiler houses at the farms. Of the swabs, 42.5% were Campylobacter positive. Most positive samples were found during July, August and September, while the lowest number of positive samples were found during January, February, March and April. Of the flocks, 5.5% were Salmonella positive, but no seasonal variation was observed. For each flock, the presence of Campylobacter and Salmonella was recorded in order to estimate the possible correlation between colonisation with the two pathogens. In conclusion, no significant effects on intensive cleaning and disinfection procedures on Campylobacter occurrence could be demonstrated, and no significant correlation between occurrence of Campylobacter and Salmonella infections in Danish broilers could be demonstrated which is in contrast to previous observations on concurrent colonisation of broilers with these two zoonotic pathogens.