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.

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.

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.

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.

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.

Surveillance of selected post-caesarean infections based on electronic registries: validation study including post-discharge infections

The importance of surveillance of post-discharge infections has increased as a consequence of shorter hospital stay after surgical procedures. This study examined the ability of a computer-based surveillance system to identify urinary tract infections (UTIs) and postoperative wound infections (PWIs) within 30 days after caesarean section. We assessed the use of data from various electronic registries to identify patients with post-caesarean UTI and PWI classified according to a reference standard. The standard was based on information from medical records and self-reported data (questionnaire) using modified Centers for Disease Control and Prevention definitions. The sensitivity of the computer system in detecting UTI diagnosed during hospital stay, readmission or at visits to hospital outpatient clinics was 80.0%; the specificity was 99.9%. For post-discharge UTIs diagnosed outside the hospital, sensitivity and specificity were 76.3% and 99.9%, respectively. For PWIs diagnosed in hospital and post-discharge outside hospital, sensitivities were 77.1% and 68.9%, and the specificities 99.5% and 98.2%. We conclude that a computer-based surveillance system may identify in-hospital infections and post-discharge infections with a relatively high sensitivity and excellent specificity.

Highly discriminative genotyping of Chlamydia trachomatis using omp1 and a set of variable number tandem repeats

This article reports the development of a method for genotyping Chlamydia trachomatis, using PCR and sequencing of omp1, supplemented with three new variable number tandem repeat (VNTR) loci of C. trachomatis. Typeability, reproducibility and discriminatory power were assessed using four groups of samples: two groups (I and II) of C. trachomatis-positive patients and their positive partner(s), one group (III) of patients with recurrent or persistent C. trachomatis infections, and one group (IV) comprising samples containing a newly discovered mutant strain with a 377-bp deletion in the cryptic plasmid, the new variant C. trachomatis (nvCT). The VNTR loci (designated CT1335, CT1299, and CT1291) were all single nucleotide repeats chosen for maximal mutability and variation. In the study material, nine variants of CT1335, eight variants of CT1299 and five variants of CT1291 were found. The discriminatory power (D) of omp1 in the present material was D(omp1) = 0.69. Ds for VNTRs CT1335, CT1299 and CT1291 were 0.53, 0.74 and 0.74, respectively. The resolution power of the omp1-VNTR assay was 0.94. Stability over time of the VNTRs was investigated and found to be adequate for epidemiological studies. Using this genotyping assay, it was confirmed that the nvCT strain was indeed a clone. These results indicate that, with this novel method, strains of C. trachomatis can be individually identified, and epidemiological associations established.

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.

Reasons for Chlamydia trachomatis testing and the associated age-specific prevalences

OBJECTIVE

to assess the age- and sex-specific prevalence of Chlamydia trachomatis infection according to the indications for testing. This was done as part of a health technology assessment to identify the populations that would benefit most from universal screening, and to identify ongoing potential superfluous testing that could liberate resources to be used for targeted screening programs.

METHODS

In Aarhus County, Denmark, population of 630,000, data were collected on 11,423 persons who were being tested for C. trachomatis (10,351 females and 1072 males). Indicated on the request slip were: the sex, the age and the reasons for testing (infected partner; planned transcervical procedure; symptoms consistent with C. trachomatis infection; or routine testing). All samples were analyzed by the Ligase Chain Reaction.

RESULTS

More than 90% of all the tests were conducted in women. The majority of tests were performed in the 21-25 years age group but the prevalence was highest in the 16-20 years age group (7.2%; 95% CI: 5.4%-9.3%). A total of 25% of all tests were carried out in asymptomatic women above the age of 30 in whom the prevalence was only 1.3% (95% CI: 0.8%-1.9%). More than three times as many women (5.8%) than men (1.7%) were tested as sexual partners to C. trachomatis-infected index patients but the risk of infection was highest among men. In women who were tested prior to a transcervical procedure, the prevalence was highest (5.5%; 95% CI: 1.8%-12.4%) in the 16-20 years age group, whereas most samples were obtained in women aged 31-35 years in whom the prevalence was only 0.8% (0.2%-2.3%).

CONCLUSIONS

The prevalence of C. trachomatis infection justifies the screening of asymptomatic individuals below 30 years of age. At present, however, 25% of all tests are requested in asymptomatic women above the age of 30. It might be advisable to use the resources for systematic universal screening of younger individuals rather than to continue the current opportunistic screening of older women.

Managing partners of people diagnosed with Chlamydia trachomatis: a comparison of two partner testing methods

OBJECTIVE

To compare the effectiveness of "home sampling" with that of "office sampling" for testing partners to men and women infected with Chlamydia trachomatis.

METHOD

A randomised controlled effectiveness trial took place in the general community in Denmark. 1300 index women and 526 index men (>/=18 years) with a positive test result for C trachomatis were identified. Of these, 414 index women and 148 index men gave implied consent. Index patients were randomly assigned to provide their partner(s) through the past 12 months with either (1) a kit by which partner(s) could be tested by home sampling, or (2) a kit by which partner(s) could only be tested by seeing a healthcare professional (office sampling). The mainoutcome measure was the proportion of index patients who had at least one partner tested for C trachomatis.

RESULTS

The proportion of index women with at least one partner tested was higher in the home sampling group (0.26) than in the office group (0.12) (difference 0.14; 95% CI 0.10 to 0.19; p<0.0001) and so it was for index men (0.15 v 0.03; difference 0.12; 95% CI 0.07 to 0.16; p<0.0001). Also the proportion of index women for whom at least one partner was identified as infected was higher in the home sampling group compared with the office group (0.11 v 0.07, p=0.01). The corresponding figures for index men were 0.06 v 0.01, p=0.02.

CONCLUSION

The effectiveness of partner testing is higher when partners of C trachomatis infected patients are offered home sampling than when they are offered office sampling.

Prevalence of resistance to ampicillin, gentamicin and vancomycin in Enterococcus faecalis and Enterococcus faecium isolates from clinical specimens and use of antimicrobials in five Nordic hospitals

We determined the species distribution and prevalence of ampicillin resistance, high-level gentamicin resistance (HLGR) and vancomycin resistance among clinical enterococcal isolates from five Nordic laboratories (Bergen, Tromsø, Uppsala, Aarhus and Reykjavik). Isolates represented three different groups: (i) all blood culture isolates from 1999; (ii) consecutive in-patient isolates (maximum 40); and (iii) consecutive outpatient isolates (maximum 40) collected during March to May 2000. Antimicrobial use data were collected at the national and hospital level. A high proportion (31.4%) of Enterococcus faecium was detected among blood culture isolates, in contrast to only 4.2% among isolates from outpatients. Ampicillin resistance was not found in Enterococcus faecalis, in contrast to 48.8% in E. faecium isolates. HLGR rates varied considerably between laboratories (1.1-27.6%). Acquired vancomycin resistance was not detected. There were no significant differences in the prevalences of HLGR between in-patient and outpatient isolates at individual hospitals. A cluster of clonally related ampicillin-resistant and HLGR E. faecium isolates was demonstrated in one of the hospitals. The lowest level of hospital antimicrobial use, the lowest proportion of E. faecium and the lowest prevalence of resistance were observed in Reykjavik. The study showed a relatively low level of resistance in enterococci, as compared with most European countries and the USA. However, there were large differences between hospitals with regard to the relative proportion of E. faecium isolates, their susceptibility to ampicillin and gentamicin, as well as the prevalence of HLGR in E. faecalis isolates. This indicates a potential for further improvement of antibiotic policies, and possibly hospital infection control, to maintain the low resistance levels observed in these countries.

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.

Effectiveness of a mass media campaign to recruit young adults for testing of Chlamydia trachomatis by use of home obtained and mailed samples

OBJECTIVE

To evaluate the effectiveness of a structured information campaign aiming to recruit young adults for a Chlamydia trachomatis test by use of a non-invasive, home obtained and mailed sample.

METHODS

All individuals aged 21-23 living in Aarhus county, Denmark (30 000 young adults) were offered a mailed home sampling test for C trachomatis as part of a structured 14 week information campaign on chlamydia. The kit for home sampling could be requested by leaving a message on an answering machine or through a website on the internet.

RESULTS

During the campaign 119 of 15 000 women (0.8%) and 64 of 15 000 men (0.4%) were tested. Prevalence of infection was 8.4% (10/119) and 7.8% (5/64) in females and males, respectively. Four infections in women (4/10=40%) and three infections in men (3/5=60%) were asymptomatic.

CONCLUSIONS

The mass media campaign had only a limited effect, and there is a need for more effective outreach programmes to recruit young asymptomatic individuals for C trachomatis testing.

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.

A procedure for evaluation and documentation of susceptibility test methods using the susceptibility of Klebsiella pneumoniae to ciprofloxacin as a model

A new procedure for the evaluation and documentation of susceptibility test methods is described. To illustrate the procedure, four basically different susceptibility test methods were examined in a routine laboratory. The test parameter detection of decreased susceptibility to ciprofloxacin (breakpoint MIC 0.25 mg/L) among 94 selected isolates of Klebsiella pneumoniae was used. In addition to comparison of frequency histograms and regression analysis, the accuracies of the susceptibility test methods were determined using the receiver operating characteristic procedure. For each of the methods, the sensitivity (SN), specificity (SP), positive predictive value (PV+) and negative predictive value (PV-) for detection of decreased susceptibility to ciprofloxacin were calculated and plotted against a range of ciprofloxacin inhibition zones determined by the various susceptibility test methods or MICs determined by the Etest (Etest MICs). The results illustrate the accuracy and the robustness of the methods, which can be used to expose the need for training and instruction of laboratory staff. It becomes possible to optimize and justify the choice of inhibition zone breakpoints or Etest MIC breakpoints according to the SN and SP of the method employed. Furthermore, the consequences of adjustments of these breakpoints on the PV+ and PV- can be analysed and related to different clinical and epidemiological situations. We believe that our approach can be used as a model for the evaluation and documentation of susceptibility test methods in general.

[The value of vaginal swabs]

INTRODUCTION

The use of culture of vaginal secretions by physicians and their use of microscopy of vaginal secretions were assessed.

METHODS

The study was conducted partly as a registration of all microbiological requests and reports from the Department of Clinical Microbiology in a selected period, and partly as a questionnaire sent to all general practitioners (GPs) and specialists in obstetrics and gynaecology in the county of Arhus.

RESULTS

In only 19% of 1,354 vaginal swabs received in a month could the findings lead to a specific antimicrobial treatment; 48% of these cases could be diagnosed by microscopy of vaginal secretions alone. Sixty-four per cent of the physicians returned the questionnaire. Half of the specialists and 60% of the GPs performed microscopy. Twenty-five per cent of the physicians treated patients solely on the basis of clinical symptoms.

DISCUSSION

General culture of vaginal secretions has a limited clinical value. The diagnosis in patients complaining of vaginal discharge can often be made by microscopy. There is, however, a need for training GPs in microscopy, as well as specialists.

Population-based study of the risk and short-term prognosis for bacteremia in patients with liver cirrhosis

We examined the risk of bacteremia in patients with liver cirrhosis (compared with the risk for all Danish citizens >20 years of age who were living in North Jutland County, Denmark), as well as the type of bacteremia and the 30-day case-fatality rate. We used the Danish National Registry of Patients to identify 1339 patients with liver cirrhosis, and we used the North Jutland County Bacteremia Database to identify episodes of bacteremia. We observed 117 cases of bacteremia in patients with liver cirrhosis (11.0 cases were expected), which yielded a standardized incidence ratio of 10.5 (95% confidence interval [CI], 8.8-12.7). Sixty-two cases of bacteremia were nosocomial infections. There were 53 cases of gram-positive bacteremia, 55 cases of gram-negative bacteremia, and 8 cases of polymicrobial bacteremia (1 case of candidemia was excluded from the analysis). The most common cause of death was bleeding from gastroesophageal varices; the second most common cause of death was infection in the respiratory system. The 30-day case-fatality rate was 0.53 (95% CI, 0.39-0.73). Patients with liver cirrhosis had an increased risk of bacteremia and a poor prognosis.

Home sampling versus conventional swab sampling for screening of Chlamydia trachomatis in women: a cluster-randomized 1-year follow-up study

We compared the efficacy of a screening program for urogenital Chlamydia trachomatis infections based on home sampling with that of a screening program based on conventional swab sampling performed at a physician's office. Female subjects, comprising students at 17 high schools in the county of Aarhus, Denmark, were divided into a study group (tested by home sampling) and a control group (tested in a physician's office). We assessed the number of new infections and the number of subjects who reported being treated for pelvic inflammatory disease (PID) at 1 year of follow-up; 443 (51.1%) of 867 women in the intervention group and 487 (58.5%) of 833 women in the control group were available for follow-up. Thirteen (2.9%) and 32 (6.6%) new infections were identified in the intervention group and the control group, respectively (Wilcoxon exact value, P=.026). Nine (2.1%) women in the intervention group and 20 (4.2%) in the control group reported being treated for PID (P=.045), indicating that a screening strategy involving home sampling is associated with a lower prevalence of C. trachomatis and a lower proportion of reported cases of PID.

High-resolution genotyping of Chlamydia trachomatis from recurrent urogenital infections

A method for Chlamydia trachomatis restriction fragment length polymorphism (RFLP) analysis and complete sequencing of omp1 was developed for use on samples collected at home, and results were compared. Genotyping by sequencing was superior to RFLP analysis. The omp1 gene in 31 clinical strains harbored few mutations compared to the same gene in ATCC reference strains. Follow-up samples obtained during a 24-week period from 31 patients showed recurrence with the same genotype in five cases and a new genotype in one case.

[Microbiological examination of patients hospitalized in Aarhus municipal hospital]

The purpose of this retrospective study was to evaluate 1) the nature, extent and relevance of the microbiological examination performed before institution of antibiotic treatment, 2) the relevance of the instituted treatment in the light of the microbiological findings or clinical diagnosis of infection. A minimum of requirements concerning microbiological examination was put forward for each clinical diagnosis of infection. Among patients with the diagnosis of sepsis, cystitis or pneumonia, 33%, 80% and 6.5%, respectively, fulfilled the minimum requirements, no attempt at microbiological examination was performed in 4.8%, 10%, and 32%, respectively. There is a need for education in relevant use of clinical microbiology e.g. samples related to focus of infection, and more consistency in the use of microbiological results.

Prolonged persistence on the ocular surface of fortified gentamicin ointment as compared to fortified gentamicin eye drops

PURPOSE

A comparative study on the elimination of gentamicin from the ocular surface and the concentration of gentamicin in the anterior chamber following application of either an ointment or eye drops containing equal concentrations (1.5%) of gentamicin.

METHODS

A disc-diffusion test was used to determine the concentration of gentamicin in fornix inferior of 10 persons. The anterior chamber concentration of gentamicin was determined in 5 cataract patients by the TDX analyzer, Abbot Laboratories, II., USA.

RESULTS

Ten minutes following application, the concentration of gentamicin was significantly higher in the eyes receiving ointment (310.6 mg/L) compared to drops (45 mg/L) (p<0.01). Furthermore, gentamicin could be detected 40 minutes after application in the eyes receiving ointment compared to 10 minutes in the eyes receiving drops. The anterior chamber concentration of gentamicin after application of either drops or ointment was lower than 0.6 mg/L and thus below detection limit.

CONCLUSIONS

The persistence of gentamicin ointment was significantly longer on the ocular surface as compared to gentamicin eye drops. Gentamycin ointment may thus provide a means to reduce the high application frequency presently in use with eye drops to treat bacterial keratitis and thereby reduce patient inconvenience, especially during nighttime.

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.

[Detection of Chlamydia trachomatis infection among young people. The effect of home-sampling and mailing the samples]

Genital Chlamydia trachomatis infection is common and treatable, but often asymptomatic. New diagnostic strategies targeting healthy individuals are therefore needed. The 17 high schools in Aarhus County, Denmark, comprising 8909 students, were cluster-randomized into an intervention group which was offered examination by mailing a urine sample (males and females) and a vaginal flush sample (females) directly to the laboratory, and a control group who were offered examination by a physician. Ninety-three percent (867/928) of the sexually experienced female responders underwent examination in the intervention group, compared with 8% (63/833) in the control group (p < 0.001). The corresponding figures for males were 97%, (430/442) and 2% (4/246), respectively (p < 0.001). Also statistically significantly more infected females and males were found in the intervention group (43 females and 11 males in the intervention group vs. five females and one male in the control group). Home sampling improves the diagnosis of C trachomatis infection among apparently healthy young individuals.

Impact of menstrual cycle on the diagnostic performance of LCR, TMA, and PCE for detection of Chlamydia trachomatis in home obtained and mailed vaginal flush and urine samples

OBJECTIVES

To assess the impact of the menstrual cycle on the diagnostic performance of various assays for detection of Chlamydia trachomatis in home obtained and mailed vaginal flush and urine specimens.

METHODS

A ligase chain reaction assay (LCR; Abbott Laboratories), a transcription mediated amplification assay (TMA; Gen-Probe), and an enzyme amplified immunoassay (PCE; Dako Diagnostics) were evaluated for their validity in detecting C trachomatis in vaginal flush, first void urine, and midstream urine specimens obtained by female high school students at home and mailed directly to the diagnostic laboratory.

RESULTS

C trachomatis was detected in 45 of 889 females (5.1%). The vaginal flush material was positive by TMA and LCR in 84% and 82% of the chlamydia positive females, respectively. First void urine was positive by TMA in 73% and by LCR in 49% of the cases. Midstream urine was positive by TMA and LCR in 69% and 42% of the females, respectively. On a pool of first void and midstream urine, PCE detected 49% of the chlamydia positive females. The overall prevalence of C trachomatis increased with increasing time after the last menstrual bleeding. In urine samples, but not vaginal flush specimens, obtained 3 weeks after the last menstrual bleeding, the sensitivities of TMA, LCR, and PCE decreased markedly suggesting that inhibitors to the assays are excreted in the urine but not in vaginal secretions at this time.

CONCLUSION

Vaginal flush samples are superior to urines for detection of chlamydia infections in females. In screening of young asymptomatic females, samples should be obtained in the latter part of the menstrual cycle.

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.

[Bacteremia in children with acute lymphoblastic leukemia]

The purpose of this study was to describe the pattern of bacterial infections in children with acute lymphoblastic leukemia. Forty-six children with ALL were treated for 119 febrile episodes. Antibiotic therapy was initiated with ampicillin and gentamicin, +/- dicloxacillin and lasted for 5-8 days. Bacterial cultures were positive in 36 of 119 febrile events. At the beginning of the febrile disease there was no difference in CRP and neutrophil count between children with positive and negative blood cultures. The maximum CRP was, however, significantly higher in children with positive blood cultures. In 75% there was no need to change the initial antibiotic treatment with ampicillin and gentamicin +/- dicloxacillin. If the temperature has been normal for 2-3 days and the neutrophil count is increasing it appears safe to discontinue the antibiotic therapy after five days when blood cultures are negative and after 7-8 days when cultures are positive.

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.

The influence of antimicrobial prophylaxis on the microbial and clinical findings in patients after autologous bone marrow transplantation

The influence of a prophylactic regimen consisting of ciprofloxacin 250 mg bid, was examined by surveillance cultures from nose, throat, axilla, gingiva, exit site of central venous catheters, blood, rectum and urine of 60 patients undergoing autologous bone marrow transplantation during a 6-year period. None of the 60 patients developed any infectious with Gram-negative rods belonging to the Enterobacteriaceae, or deep fungal infections, during hospitalization. All patients were neutropenic. Febrile episodes were seen in all patients but 3. From 13 patients, microorganisms in the blood, mostly nonhaemolytic streptococci (9/13), were cultured. Surveillance cultures did not predict later infections, but revealed the marked influence of the prophylactic antibiotics on the normal flora. Thus, mainly streptococci, coagulase-negative staphylococci and yeasts were cultured from the sites examined. It is concluded that the future objective of the microbiological surveillance should be restricted to monitoring the possible selection of drug-resistant microorganisms, and that routine cultures of blood and urine are unnecessary.

[Self-collected and mailed samples for diagnosis of urogenital Chlamydia trachomatis infection in women]

The study compared urine and vaginal flush samples, collected by women at home by endocervical and urine swabs obtained from their general practitioners, for their efficacy in the diagnosis of Chlamydia trachomatis infection. The study was a multipractice study in 33 general practices. A total of 222 women aged 18-25 years, who attended the general practitioner for a gynaecological examination, were included. Diagnostic tests-eight per woman-were performed by the polymerase chain reaction and the ligase chain reaction. A test was considered true positive if two tests or more were positive The prevalence of infection was 11.2% (23/205). Test sensitivity in samples obtained by general practitioners, samples obtained at home subjected to polymerase chain reaction, and samples obtained at home subjected to ligase chain reaction were 91%, 96%, and 100% respectively. The corresponding specificities were 100%, 92.9% and 99.5%. It is concluded that the diagnostic efficacy of samples obtained at home is as good as tests obtained by the general practitioner.

[Preventive strategies against infections in autologous bone marrow transplantation]

The routine microbial surveillance, the prophylatic antibiotic regime and the management of infections were retrospectively evaluated in 26 autologous bone marrow transplantation episodes. The surveillance specimens indicated that ciprofloxacin prophylaxis was effective in minimising gram-negative functions. The comparison between specimens taken before and during the granulocytopenic period showed a shift towards more yeast, otherwise there were no big differences. The surveillance specimen could not identify the causative organisms in case of fever. The proven infections comprised four cases of bacteriaemia and one case of gastro-enteritis. Two patients died from disseminated Aspergillus infection not diagnosed prior to death. In 11 episodes the cause of fever remained unknown. Both fungal infections were related to nearby building construction work. None of the patients with bacterial infections were in a serious clinical condition. In the future the number of routine microbial surveillance specimens will be reduced. The aim of surveillance will be to monitor the potential occurrence of fluoroquinolone resistance, and more attention will be paid to possible fungal infections. The antibacterial policy will be continued.

[Utilization of antibiotics at the Arhus Municipal Hospital. A prevalence study]

The hospital charts of 689 patients in Aarhus Municipal Hospital were surveyed on a single day in the autumn of 1994. Antibiotics were administered to 22% of the patients. In the intensive care unit, 69% of the patients received antibiotics, while 24% of the surgical patients and 17% of medical patients received antibiotics. Twenty-seven percent of 203 prescriptions were given as prophylaxis, mainly to surgical patients. Sixty-four percent were prescribed as monotherapy. Penicillins constituted 41% of the total usage of antibiotics. Antibiotics were administered orally in 55%, intravenously in 37%, topically in 5% and rectally in 3%. The prescription was noted in the medical chart for 96%, the indication in 74% and the planned duration of treatment in only 58% of the cases. Information concerning previous allergic reactions to penicillin was noted for 7% of the patients. It is concluded that the usage of antibiotics and the microbiological findings in the departments should be evaluated regularly, and the antibiotic regime and the practice of prescription adjusted accordingly.

Diagnosis of urogenital Chlamydia trachomatis infection in women based on mailed samples obtained at home: multipractice comparative study

OBJECTIVE

To compare urine and vaginal flush samples collected by women at home with endocervical and urethral swabs obtained by general practitioners for their efficacy in the diagnosis of urogenital Chlamydia trachomatis infection.

DESIGN

Multipractice comparative study.

SETTING

33 general practices and a central department of clinical microbiology in Aarhus County, Denmark.

SUBJECTS

222 women aged 18-25 years who for any reason had a gynaecological examination.

INTERVENTIONS

Endocervical and urethral swabs were obtained by the women's general practitioners. The same women when at home then collected a first void urine sample, a midstream urine sample, and a vaginal flush sample (using a vaginal pipette) and mailed them to the laboratory.

MAIN OUTCOME MEASURES

C trachomatis defected by the polymerase chain reaction and the ligase chain reaction. Eight tests for C trachomatis were performed for every woman. When two of the eight yielded positive results the patient was considered infected.

RESULTS

The overall prevalence of C trachomatis infection was 11.2% (23/205 women). Test sensitivities in samples obtained by general practitioners, samples obtained at home subjected to polymerase chain reaction, and samples obtained at home subjected to ligase chain reaction were 91%, 96%, and 100% respectively. The corresponding specificities were 100%, 92.9%, and 99.5%.

CONCLUSIONS

The diagnostic efficacy of samples obtained by women at home and mailed to the laboratory was as good as for samples obtained by a general practitioner when using the ligase chain reaction. This may have important implications for the practicability of screening for this common, often asymptomatic, and treatable infection.

[Spread of an imported multiresistant Staphylococcus aureus to other hospitals via secondary colonized patients]

A secondary spread of an imported methicillin-resistant Staphylococcus aureus strain (MRSA) to two other patients occurred within a Danish surgical ward in spite of isolation of a multitraumatized index-patient immediately after arrival from a hospital in the Mediterranean area. The two other colonized patients were later transferred to other hospitals in Denmark where it became apparent that they had developed serious infections with the MRSA strain.

IN CONCLUSION

to prevent spread of imported MRSA within Danish hospitals, strict adherence to isolation procedures and a high level of general hygiene is essential not only when patients are transferred from hospitals situated in endemic areas of MRSA abroad, but also when admitted from Danish hospital wards where known cases of colonisation or infection with MRSA exist.

[Peritonitis in continuous ambulatory peritoneal dialysis. Culture of peritoneal dialysate fluid]

Conventional aerobic and anaerobic culture of peritoneal dialysate effluent from patients in continuous peritoneal dialysis (CAPD) was compared to culture in a semiautomated blood culture system. During a two-year period 78 of 79 consecutive episodes of peritonitis among 45 Danish CAPD patients were cultured and the etiology of the infection found in 73 (94%). The sensitivity of the blood culture system was 88%, whereas the sensitivity of the conventional culture of the dialysate effluent was 81%. This difference is not significant (McNemar test; 0.5 > p > 0.3). The majority of isolates were Gram-positive bacteria dominated by coagulase-negative staphylococci (38%). In comparison, only 2% of the cultures of peritoneal dialysate effluent taken within the same period from patients without clinical signs of peritonitis were positive. All the Gram-positive aerobic bacteria were sensitive to vancomycin whereas 97% of the Gram-negative aerobic bacteria were sensitive to gentamicin. An initial empiric treatment of peritonitis with a combination of vancomycin and gentamicin is recommended.

[Peritonitis in continuous ambulatory peritoneal dialysis. An evaluation of the empiric initial antibiotic treatment]

Retrospectively, the clinical outcome and the initial empiric antibiotic treatment of peritonitis in 106 patients on continuous ambulatory peritoneal dialysis (CAPD) were evaluated during a two-year period. A mean frequency of 0.89 episodes of peritonitis per year of dialysis was found. There was a tendency towards an increased frequency of peritonitis in older patients. Diabetic patients constituted a younger age group and had a tendency towards having a lower risk of peritonitis. Patients with polycystic renal disease had a significantly increased risk. The risk of episodes with coagulase-negative staphylococci increased significantly with age. Repeated peritonitis episodes with coagulase-negative staphylococci was associated with a significant increase in the appearance of methicillin drug resistance. Carriers of Staphylococcus aureus had a significantly increased risk of Staphylococcus aureus peritonitis. Microorganisms were cultured in 94% of the episodes. The initial antibiotic therapy was only sufficient in 66% due to antimicrobial drug resistance. The initial antibiotic treatment was changed in 58% of the episodes. The treatment could have been changed to antibiotics with a narrower antimicrobial spectrum in 51% of the episodes. Relapse was seen in 11% of culture positive episodes. In 16% of the episodes (29% of patients with peritonitis) it was necessary to remove the dialysis catheter and transfer the patient to haemodialysis to clear the infection. Only 15% of these patients returned to CAPD again. We found that an initial empiric antibiotic regime of vancomycin combined with an aminoglycoside is to be recommended as achieving an antibiotic coverage of 88%, and this is now the standard regime in the department.

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.

Use of PCR and direct immunofluorescence microscopy for confirmation of results obtained by Syva MicroTrak Chlamydia enzyme immunoassay

A procedure for use of the Amplicor Chlamydia PCR with the Syva MicroTrak enzyme immunoassay (EIA) medium was developed, and the performance of the Syva MicroTrak EIA was evaluated by use of PCR and the Syva MicroTrak direct immunofluorescence assay (DFA) as confirmatory methods. PCR detected Chlamydia organisms at a 10-fold greater dilution than did DFA. Of 366 specimens, 119 specimens were positive by both PCR and DFA, 6 specimens were positive only by PCR, and 241 specimens were negative by both PCR and DFA. Subsequently, DFA and the developed PCR procedure were used prospectively for confirmation of EIA results in a defined negative gray zone between the cutoff value and 30% of the cutoff value (70% below the cutoff value). All specimens with results above the EIA cutoff value were also subjected to confirmation with DFA and PCR. EIA was performed on 7,748 endocervical swab specimens, of which 494 (6.4%) were subjected to confirmation, and on 968 male urethral swab specimens, of which 185 (19.1%) were subjected to confirmation. A "gold standard" was based on the findings by DFA and PCR, and divergent results were resolved by a major outer membrane protein-based PCR. Forty-five of 160 female specimens (28.1%) and 11 of 93 male specimens (11.8%) within the defined negative gray zone were found to be positive. Of 334 female specimens having absorbance unit (AU) values above the EIA cutoff value, 258 could be confirmed, thereby giving a positive predictive value of 77% (258/334). Accordingly, the positive predictive value with male specimens was 95% (87/92). The prevalence of Chlamydia trachomatis-positive specimens was 3.9% (303/7,748) in females and 10.1% (98/968) in males. All male specimens having AU values above 1.0 in the EIA were confirmed positive. In contrast to this, 16 females with AU values above 1.0 in the EIA could not be confirmed positive with either DFA or PCR. The mean age of these females was higher than that of patients testing negative for C. trachomatis (P < 0.005). This might suggest an age-dependent change in vaginal colonization with an organism(s) crossreacting in the EIA. Thus, the PCR procedure developed can be used for confirmation of EIA results, testing specimens with AU values in the defined negative gray zone improves the sensitivity of EIA, and all specimens testing positive in EIA should be subjected to confirmation.

Changing etiology of bacteremia in patients with hematological malignancies in Denmark

To ascertain whether the microbiological etiology of bacteremia among patients with hematological malignancies has changed in Denmark, the species distribution of clinically relevant blood culture isolates from the Hematological Department at Rigshospitalet, Copenhagen in 1990 was compared with 2 previous studies (1970-72; 1981-85). In addition, time trends of the etiology of bacteremia among hematological patients in Copenhagen (eastern Denmark) and in Arhus (western Denmark) were compared. In contrast to many other studies, a significant increase in the proportion of Gram-negative aerobes was observed in Copenhagen (from 43% in 1981-85 to 55% in 1990; p < 0.05), whereas in Arhus the proportion of Gram-positive aerobes increased steadily during the 1980s (from 34% to 51%; p < 0.05). In Copenhagen, non-hemolytic streptococci and Xanthomonas maltophilia increased significantly and accounted for 10% (p < 0.01) and 5% (p < 0.05) respectively, of all isolates in 1990, whereas Staphylococcus aureus during the 2 decades studied decreased from 25% to 8% (p < 0.001). In both regions, a decrease was observed in the proportion of Pseudomonas aeruginosa which accounted for only about 5% of all isolates in 1990. No changes were observed in the rates of anaerobes and yeasts. Several factors may contribute to the reported differences in the etiology of bacteremia among hematological patients, e.g. criteria used to assign the clinical significance of the isolate, blood culture system used, practice of using indwelling intravenous catheters, different policies with respect to antimicrobial treatment, and the degree of immunosuppression. A local surveillance of blood culture isolates is mandatory if changes in etiology and resistance development are to be detected.

Monitoring antimicrobial drug resistance in hospital microorganisms. Definition of problems and methods

Hospital infections continue to be an important problem. Changes in patient categories and in the examinations and treatments offered at the hospital, probably constitute the basis upon which new types of infections and new groups of infecting microorganisms continually emerge. The treatment of patients with hospital infections may become complicated by the emergence of drug resistance in the infecting microorganisms. The situation varies between hospitals, and this necessitates a local microbiological monitoring. Prerequisites of a surveillance system in general are described and illustrated by a system monitoring antimicrobial resistance in a Danish county. A specific computer system (software) for the processing of clinical microbiological results was developed by the author to make the local microbiological monitoring possible. Computer-assisted analyses for an evaluation of the statistical association of drug resistance traits (phenotype) were also developed. Data on local drug resistance patterns were systematically obtained and analysed in a seven-year study comprising several hundred thousands specimens. Drug resistance genotypes were determined for selected groups of microorganisms (e.g. coagulase-negative staphylococci) in various periods. Data from these studies emphasize that it is important to correlate information about resistance phenotypes of all clinical isolates with the resistance genotypes of selected strains in the monitoring of plasmid mediated resistance and its dissemination. These findings agree well with the results of other but generally less comprehensive studies in the literature. In a study of outpatients treated with a particular antimicrobial (tetracycline), it was shown that this drug selected for plasmid mediated multiple drug resistance in the normal flora of the patients. On the basis of these results and the literature, a general model for the emergence and spread of antimicrobial drug resistance is discussed. Examinations of quantitative relationships between antimicrobial usage and microbial resistance are also reviewed. Analysis of the statistical correlation between various measures of antimicrobial use and the prevalence of microbial resistance in the Danish county corroborates the observation that general changes in prevalence of a particular resistance trait seem to be best explained by taking the mechanisms of co-selection by other antimicrobials into consideration.

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.

Antimicrobial usage and microbial resistance in a university hospital during a seven-year period

The prevalence of antimicrobial resistance among Staphylococcus epidermidis, Staph. aureus and Escherichia coli isolated in a university hospital, and the usage of antimicrobial agents within and outside the hospital was established for a seven-year period. The overall resistance to antimicrobial agents increased markedly for Staph. epidermidis but remained constant for the two other species. In Staph. epidermidis, a pronounced increase was seen in prevalence of resistance to penicillin, sulphonamides, trimethoprim, erythromycin and chloramphenicol, whereas resistance to streptomycin and tetracycline decreased. The trends in usage of beta-lactam antibiotics were identical within and outside hospital as opposed to the use of erythromycin and sulphonamides. The highest degree of correlation between antimicrobial usage and resistance to an antimicrobial was obtained using a corrected figure for antimicrobial usage paying regard not only to the use of a particular antimicrobial agent but also to a fraction of the usage of other antimicrobials which may co-select for the resistance trait.

[Accumulated microbiological data. Surveillance of infection/antibiotic policy]

Database reviews of the findings in bacteriological specimens from a period of six years from patients in a department of haematology are employed as a model of how cumulative data about the microorganisms isolated may be employed for surveillance of accumulated infections and in the organization of the antibiotic policy of a department. During the period of observation, the standard treatment with antibiotics for febrile episodes in granulocytopenic patients was altered to piperacillin and netilimicin on the basis of the frequent occurrence of Gram-negative rods including Pseudomonas aeruginosa in blood cultures. It is concluded that accumulated microbiological data is of value for a clinical department and that analysis of the data does not constitute an increased work-load provided that the microbiological reports are routinely registered in a database.

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.

A microcomputer-assisted bacteriology reporting and information system

A microcomputer system for recording and reporting all specimens processed by a routine laboratory of clinical bacteriology is described. The system is based upon two multi-user microcomputers and all functions are carried out within the laboratory by the medical, technical and clerical staff. Data are recorded using visual display units ( VDU *s) and the laboratory has issued about 2700 final reports per week since January 1981. Data on all specimens are kept for immediate recall on a VDU for a period of about 6 weeks and hereafter stored on floppy disks. The computer system also produces laboratory statistics for internal use, epidemiological information for the surveillance of nosocomial infections, and makes accounting information for the accountants office.

The influence of long-term treatment with mecillinam on fecal Escherichia coli

The influence of long-term treatment with a low dose of pivmecillinam on the fecal flora was investigated. Before treatment Escherichia coli was detected in about 88% of 30 outpatients with chronic recurrent urinary tract infections, but after 1-2 months only about 55% had detectable E. coli in the intestinal flora. E. coli resistant to mecillinam were not selected during the therapy. A similar group of patients treated with nitrofurantoin showed neither changes in the E. coli flora nor in the resistance pattern.