Associations between blood cultures after surgery for colorectal cancer and long-term oncological outcomes.

BACKGROUND: Systemic inflammation following curative surgery for colorectal cancer may be associated with increased risk of recurrence. [Correction added on 29 November 2019, after first online publication: text amended for accuracy.] This study investigated whether a clinically suspected infection, for which blood cultures were sent within 30 days after surgery for colorectal cancer, was associated with long-term oncological outcomes. METHODS: This register-based national cohort study included all Danish residents undergoing surgery with curative intent for colorectal cancer between January 2003 and December 2013. Patients who developed recurrence or died within 180 days after surgery were not included. Associations between blood cultures taken within 30 days after primary surgery and overall survival, disease-free survival and recurrence-free survival were analysed using Cox regression models adjusted for relevant clinical confounders, including demographic data, cancer stage, co-morbidity, blood transfusion, postoperative complications and adjuvant chemotherapy. RESULTS: The study included 21 349 patients, of whom 3390 (15·9 per cent) had blood cultures taken within 30 days after surgery. Median follow-up was 5·6 years. Patients who had blood cultures taken had an increased risk of all-cause mortality (hazard ratio (HR) 1·27, 95 per cent c.i. 1·20 to 1·35; P < 0·001), poorer disease-free survival (HR 1·22, 1·16 to 1·29; P < 0·001) and higher risk of recurrence (HR 1·15, 1·07 to 1·23; P < 0·001) than patients who did not have blood cultures taken. CONCLUSION: A clinically suspected infection requiring blood cultures within 30 days of surgery for colorectal cancer was associated with poorer oncological outcomes.

ANTECEDENTES: La inflamación sistémica en el cáncer colorrectal puede asociarse con un aumento del riesgo de recidiva. En este estudio se investigó si la sospecha clínica de infección, en la que se obtuvieron cultivos de sangre periférica durante los primeros 30 días de la cirugía por cáncer colorrectal, se asociaba con los resultados oncológicos a largo plazo. MÉTODOS: Se trata de un estudio de cohortes de un registro de una base de datos nacional, que incluyía todos los sujetos residentes en Dinamarca sometidos a cirugía por cáncer colorrectal con intención curativa desde enero de 2003 a diciembre de 2013. Los pacientes con recidiva o que fallecieron durante los primeros 180 días después de la cirugía fueron excluidos. Se estimaron las asociaciones entre los cultivos de sangre periférica efectuados en los primeros 30 días tras la cirugía primaria y la supervivencia global, supervivencia libre de enfermedad y supervivencia libre de recidiva mediante modelos de regresión de Cox, ajustados por variables clínicas confusoras relevantes (incluyendo datos demográficos, estadio del cáncer, comorbilidad, transfusión de sangre, complicaciones postoperatorias y quimioterapia adyuvante). RESULTADOS: El estudio incluyó 21.349 pacientes, de los cuales en 3.390 (16%) se habían obtenido cultivos de sangre periférica durante los primeros 30 días tras la cirugía. La mediana de seguimiento fue de 5,6 años. Los pacientes en los que se había obtenido cultivos de sangre periférica presentaron un riesgo aumentado de mortalidad por cualquier causa (cociente de riesgos instantáneos, hazard ratio, HR 1,27, i.c. del 95% 1,20-1,35; P < 0.0001), peor supervivencia libre de enfermedad (HR 1,22, i.c. del 95% 1,16-1,29; P < 0,0001) y mayor riesgo de recidiva (HR 1,15, i.c. del 95% 1,07-1,23; P < 0,0001) que los pacientes en los que no se habían obtenido cultivos. CONCLUSIÓN: La presencia de una infección sospechada clínicamente para la cual se requiere obtener cultivos de sangre periférica en los primeros 30 días tras cirugía por cancer colorrectal se asoció con peores resultados oncológicos.

A comparison of GenomEra® GBS PCR and GeneXpert ® GBS PCR assays with culture of GBS performed with and without broth pre-enrichment.

This study was designed to compare the performance of GeneXpert® and GenomEra® group B streptococcus (GBS) PCR assays, held up against standard culture of GBS performed with and without broth pre-enrichment. In Denmark, the strategy for preventing early onset GBS infection (EOGBS) is risk factor based. Three hundred and sixty six women fulfilling one or more of the criteria for presence of risk factors for EOGBS were prospectively included. Rectovaginal swab samples were taken intrapartum and tested bed-site by the GenomEra® and the GeneXpert® GBS PCR assays and cultured at the microbiology laboratory using Granada agar plates with and without prior growth of sampling material in selective enrichment broth. Among 366 participants tested intrapartum, 99 were GBS-positive by culture, 95 by GenomEra, and 95 by GeneXpert. Compared with culture, the GenomEra and the GeneXpert performed with a sensitivity of 91.8% and 91.7% and a specificity of 98.1% and 97.3%, respectively. A combined reference standard was established by defining true positives as either culture-positive samples or culture-negative samples where both the GeneXpert and the GenomEra GBS PCR assays were positive. Using this, the sensitivity increased to 92.2% and the specificity to 99.6% for GenomEra and to 92.0% and 96.8% for GeneXpert. The use of selective broth enrichment found only three additional GBS culture-positive samples. The performance of the two PCR methods examined was very similar and close to the findings by culture, and both PCR assays are thus applicable as rapid intrapartum bed-site tests.

One-year incidence of prosthetic joint infection in total hip arthroplasty: a cohort study with linkage of the Danish Hip Arthroplasty Register and Danish Microbiology Databases.

OBJECTIVE: To examine the trend of Prosthetic Joint Infections (PJI) following primary total hip arthroplasty (THA) and the antimicrobial resistance of the bacteria causing these infections. MATERIALS AND METHODS: We identified a population-based cohort of patients in the Danish Hip Arthroplasty Register (DHR) who had primary THA and received their surgery in Jutland or Funen between 2005 and 2014. We followed the patients until revision, emigration, death, or up to 1-year of follow-up. Data from the DHR were combined with those from microbiology databases, the National Register of Patients, and the Civil Registration System. We estimated the cumulative 1-year incidence of PJI for two 5-year periods; 2005-2009 and 2010-2014. The hazard ratio of PJI as a measure of relative risk after adjusting for multiple risk factors was calculated. RESULTS: Of 48,867 primary THAs identified, 1120 underwent revision within 1 year. Of these, 271 were due to PJI. The incidence of PJI was 0.53% (95% confidence interval (CI): 0.44; 0.63) during 2005-2009 and 0.57% (95% CI: 0.49; 0.67) during 2010-2014. The adjusted relative risk was 1.05 (95% CI: 0.82; 1.34) for the 2010-2014 period vs the 2005-2009 period. The most common micro-organisms identified in the 271 PJI were Staphylococcus aureus (36%) and coagulase-negative staphylococci (CoNS) (33%); others commonly identified included Enterobacteriaceae, enterococci, and streptococci. Antimicrobial resistance to beta-lactams and gentamicin did not change during the study period. CONCLUSION: The risk of PJI within 1-year after primary THA and the antimicrobial resistance of the most prevalent bacteria remained unchanged during the 2005-2014 study period.

Reduction of intrapartum antibiotic prophylaxis by combining risk factor assessment with a rapid bedside intrapartum polymerase chain reaction testing for group B streptococci.

OBJECTIVE: To investigate the impact of administering Intrapartum Antibiotic Prophylaxis (IAP) to laboring women with one or more risk factors for Early Onset Group B Streptococcal neonatal infection (EOGBS) based on the result of a rapid bedside test for Group B Streptococci (GBS). STUDY DESIGN: Quality assessment study. METHODS: Three-hundred-sixty-six laboring women admitted to our maternity ward, with one or more risk factors for EOGBS, were prospectively included. Rectovaginal swab-samples were examined bedside by the GenomEra® GBS Polymerase Chain Reaction (PCR) assay upon admission. Time from administration of IAP to delivery was registered. According to national guidelines, one-hundred-two women mandatorily received IAP independent of the PCR test result fulfilling one of the following three risk factors: prior infant with EOGBS, preterm labor before 35 gestational week, temperature ≥ 38 °C during labor. Women with GBS bacteriuria during current pregnancy, rupture of membranes ≥ 18 h IAP, and preterm labor between 35 and 37 gestational week, received IAP solely if the PCR test was positive. Predictive values were calculated for each risk factor. RESULTS: Previous GBS bacteriuria was strongly associated (PPV = 71%) with a positive GBS PCR test, whilst the corresponding positive percent of ROM > 18 h and of GA 35-37 was only PPV = 16% and 22%, respectively. Seventy-four women, 74/251 (31%), received IAP because they were GBS PCR positive. IAP was thus reduced by about two-thirds compared to the risk-based strategy of offering IAP to all women with one or more risk factors for EOGBS. Two women, 2/254 (0.8%), received inferior care, as they did not receive IAP within the recommended 4 h prior to delivery due to the extra time spend on the test procedure. CONCLUSION: Bedside intrapartum PCR testing of women with risk factors for EOGBS effectively diminishes use of IAP during labor compared to the present risk factor-based strategy alone. In this project, the extra time spend on the PCR test procedure did not lead to noticeable delay in IAP.

Effectiveness of an electronic hand hygiene monitoring system in increasing compliance and reducing healthcare-associated infections.

During an interventional study in a nephrology department, we investigated the effect of an electronic hand hygiene monitoring system on the hand hygiene compliance of healthcare workers (N = 99) and hospital-acquired bloodstream infections. The hand hygiene compliance of the doctors and nurses improved significantly during the intervention phase when they received group and individual feedback based on actionable insights from the electronic hand hygiene monitoring system. The improvements in hand hygiene compliance were associated with a significant reduction in the number of hospital-acquired bloodstream infections.

Prioritize effluent quality, operational costs or global warming? - Using predictive control of wastewater aeration for flexible management of objectives in WRRFs.

This study presents a general model predictive control (MPC) algorithm for optimizing wastewater aeration in Water Resource Recovery Facilities (WRRF) under different management objectives. The flexibility of the MPC is demonstrated by controlling a WRRF under four management objectives, aiming at minimizing: (A) effluent concentrations, (B) electricity consumption, (C) total operations costs (sum electricity costs and discharge effluent tax) or (D) global warming potential (direct and indirect nitrous oxide emissions, and indirect from electricity production) . The MPC is tested with data from the alternating WRRF in Nørre Snede (Denmark) and from the Danish electricity grid. Results showed how the four control objectives resulted in important differences in aeration patterns and in the concentration dynamics over a day. Controls B and C showed similarities when looking at total costs, while similarities in global warming potential for controls A and D suggest that improving effluent quality also reduced greenhouse gasses emissions. The MPC flexibility in handling different objectives is shown by using a combined objective function, optimizing both cost and greenhouse emissions. This shows the trade-off between the two objectives, enabling the calculation of marginal costs and thus allowing WRRF operators to carefully evaluate prioritization of management objectives. The long-term MPC performance is evaluated over 51 days covering seasonal and inter-weekly variations. On a daily basis, control A was 9-30% cheaper on average compared to controls A, D and to the current rule-based control. Similarly, control D resulted on average in 35-43% lower greenhouse gasses daily emission compared to the other controls. Difference between control performance increased for days with greater inter-diurnal variations in electricity price or greenhouse emissions from electricity production, i.e. when MPC has greater possibilities for exploiting input variations. The flexibility of the proposed MPC can easily accommodate for additional control objectives, allowing WRRF operators to quickly adapt the plant operation to new management objectives and to face new performance requirements.

Surveillance of hospital-acquired infections based on electronic hospital registries.

Computer-assisted surveillance of hospital-acquired infections (HAIs) was compared with conventional manual registration (our gold standard i.e. reference method) by chart reviews of nosocomial infections in patients from surgical and medical departments. By combining selected infection parameters from various electronic hospital registries, the computer detected general HAIs with a sensitivity of 94% and a specificity of 47%. However, defining septicaemia, urinary tract infection (UTI), pneumonia and postoperative wound infection (PWI) specifically by sets of simplified criteria (infection parameters), computer-assisted surveillance was able to detect these infections with a sensitivity ranging between 82% (UTI) and 100% (septicaemia), and a specificity ranging between 91% (PWI) and 100% (septicaemia) compared with conventional manual registration. We conclude that computer surveillance based on data collected for other purposes in electronic hospital registries is an effective method for monitoring HAIs.

Analysing risk factors for urinary tract infection based on automated monitoring of hospital-acquired infection.

Urinary tract infections account for as much as one-third of all nosocomial infections. The aim of this study was to examine previously reported characteristics of patients with hospital-acquired urinary tract infections (HA-UTI) using an automated infection monitoring system (Hospital-Acquired Infection Registry: HAIR). A matched case-control study was conducted to investigate the association of risk factors with HA-UTI. Patients with HA-UTI more frequently had indwelling urinary catheters or a disease in the genitourinary or nervous system than the controls. Automated hospital-acquired infection monitoring enables documentation of key risk factors to better evaluate infection control interventions in general or for selected groups of patients.

Automated surveillance system for hospital-acquired urinary tract infections in Denmark.

BACKGROUND: The Danish Hospital-Acquired Infections Database (HAIBA) is an automated surveillance system using hospital administrative, microbiological, and antibiotic medication data. AIM: To define and evaluate the case definition for hospital-acquired urinary tract infection (HA-UTI) and to describe surveillance data from 2010 to 2014. METHODS: The HA-UTI algorithm defined a laboratory-diagnosed UTI as a urine culture positive for no more than two micro-organisms with at least one at ≥10(4)cfu/mL, and a probable UTI as a negative urine culture and a relevant diagnosis code or antibiotic treatment. UTI was considered hospital-acquired if a urine sample was collected ≥48h after admission and <48h post discharge. Incidence of HA-UTI was calculated per 10,000 risk-days. For validation, prevalence was calculated for each day and compared to point prevalence survey (PPS) data. FINDINGS: HAIBA detected a national incidence rate of 42.2 laboratory-diagnosed HA-UTI per 10,000 risk-days with an increasing trend. Compared to PPS the laboratory-diagnosed HA-UTI algorithm had a sensitivity of 50.0% (26/52) and a specificity of 94.2% (1842/1955). There were several reasons for discrepancies between HAIBA and PPS, including laboratory results being unavailable at the time of the survey, the results considered clinically irrelevant by the surveyor due to an indwelling urinary catheter or lack of clinical signs of infection, and UTIs being considered HA-UTI in PPS even though the first sample was taken within 48h of admission. CONCLUSION: The HAIBA algorithm was found to give valid and valuable information and has, among others, the advantages of covering the whole population and allowing continuous standardized monitoring of HA-UTI.

Incidence rates of hospital-acquired urinary tract and bloodstream infections generated by automated compilation of electronically available healthcare data.

BACKGROUND: Monitoring of hospital-acquired infection (HAI) by automated compilation of registry data may address the disadvantages of laborious, costly and potentially subjective and often random sampling of data by manual surveillance. AIM: To evaluate a system for automated monitoring of hospital-acquired urinary tract (HA-UTI) and bloodstream infections (HA-BSI) and to report incidence rates over a five-year period in a Danish hospital trust. METHODS: Based primarily on electronically available data relating to microbiology results and antibiotic prescriptions, the automated monitoring of HA-UTIs and HA-BSIs was validated against data from six previous point-prevalence surveys (PPS) from 2010 to 2013 and data from a manual assessment (HA-UTI only) of one department of internal medicine from January 2010. Incidence rates (infections per 1000 bed-days) from 2010 to 2014 were calculated. FINDINGS: Compared with the PPSs, the automated monitoring showed a sensitivity of 88% in detecting UTI in general, 78% in detecting HA-UTI, and 100% in detecting BSI in general. The monthly incidence rates varied between 4.14 and 6.61 per 1000 bed-days for HA-UTI and between 0.09 and 1.25 per 1000 bed-days for HA-BSI. CONCLUSION: Replacing PPSs with automated monitoring of HAIs may provide better and more objective data and constitute a promising foundation for individual patient risk analyses and epidemiological studies. Automated monitoring may be universally applicable in hospitals with electronic databases comprising microbiological findings, admission data, and antibiotic prescriptions.

Utilization of blood cultures in Danish hospitals: a population-based descriptive analysis.

This national population-based study was conducted as part of the development of a national automated surveillance system for hospital-acquired bacteraemia and ascertains the utilization of blood cultures (BCs). A primary objective was to understand how local differences may affect interpretation of nationwide surveillance for bacteraemia. From the Danish Microbiology Database, we retrieved all BCs taken between 2010 and 2013 and linked these to admission data from the National Patient Registry. In total, 4 587 295 admissions were registered, and in 11%, at least one BC was taken. Almost 50% of BCs were taken at admission. The chance of having a BC taken declined over the next days but increased after 4 days of admission. Data linkage identified 876 290 days on which at least one BC was taken; 6.4% yielded positive results. Ten species, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae, Enterococcus faecium, Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, Enterobacter cloacae and Klebsiella oxytoca, accounted for 74.7% of agents for this purpose classified as pathogenic. An increase in BCs and positive BCs was observed over time, particularly among older patients. BCs showed a seasonal pattern overall and for S. pneumoniae particularly. A predominance of male patients was seen for bacteraemias due to S. aureus, E. faecium and K. pneumoniae. Minor differences in BCs and positive BCs between departments of clinical microbiology underpin the rationale of a future automated surveillance for bacteraemia. The study also provides important knowledge for interpretation of surveillance of invasive infections more generally.

Effects of short-chain fatty acids on in vitro bacterial growth of Bacteroides fragilis and Escherichia coli.

Short-chain fatty acids (SCFA) are produced in the large bowel of nonruminant mammals by bacterial anaerobic fermentation. The aim of the present study was to investigate the effects of SCFA on the in vitro growth of Bacteroides fragilis and Escherichia coli. B. fragilis and E. coli isolated from fresh human clinical samples and a reference strain for each species were incubated in a meat infusion broth with increasing amounts of SCFA and grown under anaerobic conditions at a temperature of 37 degrees C. Bacterial growth was estimated by spectrophotometry. Rate of growth was calculated from the logarithmic growth phase. SCFA, in concentrations normally found in the human colon, had a significant (p<0.01) inhibitory effect of the in vitro growth rate for E. coli, while they were without effect on the in vitro growth rate of B. fragilis. It may be concluded that under in vitro conditions SCFA had growth-inhibitory effects on E. coli, while they had no effect on B. fragilis.

Phage-typing of coagulase-negative staphylococci. Factors influencing typability.

Factors influencing the phage-typability of coagulase-negative Micrococcaceae have been studied in 2,778 clinical isolates comprising A) 209 consecutive isolates from one laboratory, B) 2,107 clinical strains submitted for phage-typing for epidemiological reasons, and C) 462 strains representing all isolates of presumed clinical significance found in two laboratories during one month. The reproducibility was acceptable at duplicate repeated typing of the same strains as well as by typing epidemiologically-related pairs of strains from the same patient. Strains of Staphylococcus haemolyticus were seldom typable, whereas strains of S. epidermidis and S. hominis had a higher typability. Methicillin-resistant strains and other multiple-resistant strains were rarely typable (11-13%). The typability was higher among susceptible strains (36%) and strains resistant to penicillin only (43-50%). The typability of strains of the same species and antibiotic-resistance pattern differed between hospitals compared and decreased markedly over the years for multiple-resistant S. epidermidis isolates.

Drug resistance and plasmid profiles in Staphylococcus epidermidis in 1964 and 1986.

An examination has been made of drug resistance and plasmid content of Staphylococcus epidermidis isolated from hospital patients in 1964 and 1986. Drug resistance was much more prevalent in isolates from 1986 than in isolates from 1964. Plasmids were demonstrated in 50 of 52 strains from 1964 and in 102 of 111 strains from 1986. The majority of both drug-sensitive and drug-resistant strains harboured more than one plasmid. Of five plasmids obtained from a multiply-drug-resistant S. epidermidis, four were shown to mediate drug resistance.

Observations on multiple drug resistance in coagulase-negative staphylococci isolated in hospitals from 1975 to 1985.

Drug resistance in coagulase-negative staphylococci (CNS) isolated in hospitals since 1975 was analysed using routine laboratory data registered on a microcomputer. Resistance increased substantially in CNS during the years, especially in Staphylococcus epidermidis isolates, of which more than 50% were multiply drug resistant by 1985. Among the methicillin-resistant CNS strains, resistance to gentamicin rose from 0% in 1975 to 76% in 1985. Co-resistance to kanamycin, gentamicin, and in some cases netilmicin seemed to replace co-resistance to kanamycin and streptomycin in S. epidermidis. Gentamicin and netilmicin usage in hospital increased tenfold from 1976 to 1985.

Bacteraemia caused by hospital-type micro-organisms during hospital stay.

A sharp transition between community-type and hospital-type pathogens at the second or third day of hospital stay is often assumed. This study aimed to test whether such a threshold phenomenon exists for bloodstream infections and to examine the relationship between the proportion of infections caused by hospital-type pathogens and length of stay in the hospital. Blood stream infections were studied in a referral and a university hospital in west Denmark, and a university hospital in central Israel during three study periods (1994-1996, 1992-1995, 1989-1995 in the three hospitals respectively). No threshold effect at 2-3 days stay in the hospital could be demonstrated. However the percentage of Pseudomonas aeruginosa bloodstream infections increased constantly in the three hospitals from 1%, 1% and 7% during the first 2 days to 7%, 4%, and 14% during the third week of hospital stay (P<0.01 for all three comparisons-chi(2)for linear trends). For Candida sp. the increase was from 0%, 2%, 1% during the first 2 days to 3%, 4%, and 9% during the third week, P<0.05. Methicillin-resistant Staphylococcus aureus in Israel increased from 26% of the total number of S. aureus during the first 2 days to 69% during the third week, P<0.0001. For penicillin-resistant S. aureus in Denmark, the percentages were 84% and 100%, P<0.05.The percentage of infections caused by hospital-type pathogens increased almost linearly during the first 3 weeks of hospital stay, with no threshold effect. This trend should be taken into account when prescribing empirical therapy for nosocomial infections.

Coagulase-negative Staphylococci in Danish blood cultures: species distribution and antibiotic susceptibility.

The distribution and antibiotic susceptibility of coagulase-negative staphylococci (CoNS) isolated from blood cultures was examined in samples from hospitals covering most of Denmark. A total of 499 CoNS isolates were detected in 477 blood cultures from 340 patients and speciated as Staphylococcus epidermidis, 285; Staphylococcus hominis, 61; Staphylococcus haemolyticus, 43; Staphylococcus warneri, 12; Staphylococcus cohnii, 7; Staphylococcus saprophyticus, 4; Staphylococcus capitis, 2 and Staphylococcus lugdunensis, 1. Seventy-eight isolates could not be identified to species level and six were Micrococcus spp. In 108 (22.6%) blood culture sets, more than one CoNS strain were found, as detected by species identification, antibiogram and biotyping. Significantly more blood cultures from patients in university hospitals were drawn from central venous catheters. Comparing university and non-university hospitals, the overall antibiotic susceptibility among CoNS was only slightly different, except for methicillin and amikacin. The prevalence of methicillin-resistant strains was 35.1% in the university hospital strains vs. 25.3% in the non-university hospital strains. The overall prevalence of methicillin resistance was 32%. Great geographic variation in both species distribution and antibiotic resistance was observed. The high prevalence of S. epidermidis makes subtyping of this species important.

Quantitative culture of bronchoalveolar lavage fluid in community-acquired lower respiratory tract infections.

To evaluate the diagnostic value of quantitative bacterial culture of bronchoalveolar lavage (BAL) fluid obtained by fibreoptic bronchoscopy, 67 consecutive immunocompetent adult patients admitted to hospital with community-acquired lower respiratory tract infections from September 1997 to May 1998 were investigated. Results were compared to the findings in eight healthy control persons investigated in February 1998. There was no difference between study patients and control persons when quantitative culture of total cumulative bacterial findings or bacteria categorized as members of the oropharyngeal normal flora were compared. The culture of normal flora in bronchial washings probably reflects contamination of the lower airways with secretions from upper arways by the fibreoptic procedure itself, as fractionated sampling showed a 10-fold reduct on in quantitative culture results when a primary bronchial washing was compared to a secondary sampling from the same bronchus in the control group. Twenty-four (36%) of 67 patients were cultured as positive in the study group while all control persons were cultured as negative for bacteria categorized as potential pathogens. With a threshold value for positive culture of 10(4) cfu ml(-1) the specificity of lavage culture of potential pathogenic bacteria in relation to actual lower airway infection was 100%. Therefore, quantitative bacterial culture of potential pathogenic bacteria in BAL fluid is very specific but only positive in about one-third of unselected immunocompetent adult patients with a lower respiratory tract infection.

Intensified microbiological investigations in adult patients admitted to hospital with lower respiratory tract infections.

The objective of this study was to investigate the diagnostic yield of a programme with intensified microbiological investigations in immunocompetent adult patients with lower respiratory tract infections (LRTI). Patients in the study group were included prospectively and consecutively from September 1st 1997 to May 31st 1998 and were compared with a control group from the preceding year. A total of 67 adult patients were included in the study group and they were compared with 122 adult patients in the control group. The study group underwent fibre-optic bronchoscopy (FOB) with bronchoalveolar lavage (BAL). Only 7% in the historic control group were discharged with an aetiological diagnosis of their infections; while the diagnostic yield in the study group increased to 51% of patients. In the study group the presence of new infiltrates on chest X-ray increased the detection of a microbiological aetiology from 37% with no infiltrates to 62% with infiltrates and recent antibiotic therapy reduced the detection of a microbiological cause of infection from 61% in 36 patients who had not received antibiotic therapy to 39% in 31 patients who had received recent antibiotic therapy prior to microbiological sampling. Patients in the study group with known aetiology had higher values of inflammatory markers than patients with unknown aetiology. For Streptococcus pneumoniae infection culture and urine antigen detection were complimentary depending on recent antibiotic therapy since seven of eight culture-positive patients had not received antibiotic therapy within 72 h prior to investigation, while all four patients positive for urine antigens from S. pneumoniae had received antibiotic therapy within 72 h of urine sampling. In conclusion intensified microbiologic investigations increase the diagnostic yield from 7% to 51% of patients in the study group with an aetiologic diagnosis. Routine FOB with BAL had no apparent effect on clinical outcome and seems only justified in selected patients with severe LRTI with infiltrates on chest X-ray and signs of severe inflammation where a high diagnostic yield is achieved.

Formation of amino acid (L-leucine, L-phenylalanine) derived volatile flavour compounds by Moraxella phenylpyruvica and Staphylococcus xylosus in cured meat model systems.

A bacterial strain isolated from Danish immersion curing brine, Moraxella phenylpyruvica 0100, and a commercial meat starter culture, Staphylococcus xylosus DD34, were tested for their ability to form characteristic volatile compounds in minimal medium with the added amino acid L-leucine or L-phenylalanine under different environmental conditions (pH 5.5 and 6.0; 0 and 210 ppm nitrate; pre-incubation with and without agitation) and compared with respect to their ability to form volatile compounds in cured meat extracts and vacuum-packed cured meat cuts. The characteristic cured meat aroma precursors/compounds 3-methylbutanal and 3-methylbutanol were found to be formed in cured meat extracts and vacuum-packed cured meat cuts inoculated with M. phenylpyruvica. These volatiles are most probably formed by metabolic conversion of the amino acid L-leucine by M. phenylpyruvica, as they were also produced in minimal media with added L-leucine inoculated with this organism. The characteristic L-phenylalanine derived compound, benzaldehyde, formed by M. phenylpyruvica in minimal medium in the presence of nitrate (210 ppm), was not produced in any noticeable amount in cured meat extracts or vacuum-packed cured meat inoculated with M. phenylpyruvica. In contrast, benzacetaldehyde, which has been described as a possible metabolic product of the microbial conversion of L-phenylalanine, was found to be a characteristic volatile compound formed in cured meat extracts and vacuum-packed cured meat inoculated with M. phenylpyruvica, indicating an alternative metabolic pathway for L-phenylalanine by this organism in a cured meat environment. Even though S. xylosus was able to form volatile compounds characteristic of cured meats (3-methylbutanal, 3-methylbutanol) in minimal media with added L-leucine, this bacterial strain seemed not to be able to produce these characteristic volatiles in the studied cured meat systems. The present data imply that M. phenylpyruvica, in particular, is a potential meat starter for ensuring superior flavour development in cured meat.