Diagnostic approach for detection and identification of emerging enteric pathogens revisited: the (Ali)arcobacter lanthieri case.

An immunocompetent patient without a history of recent travel or animal exposure developed persistent abdominal bloating and cramps without diarrhoea or fever. Negative additional investigations excluded gastritis, infectious colitis, inflammatory bowel disease and neoplasia, but routine stool culture detected a Campylobacter-like organism. The isolate was obtained with use of a polycarbonate filter technique, emphasizing the importance of culture to support and validate the occurrence of emerging and new bacterial enteric pathogens. The ensuing extensive laboratory examinations proved challenging in identifying this potential pathogen. Phylogenetic marker analysis based on the 16S ribosomal RNA and rpoB gene sequences revealed that the isolate was most closely related to Arcobacter lanthieri and Arcobacter faecis. Subsequent analysis of a draft whole genome sequence assigned the isolate to A. lanthieri. We report the presence of five virulence genes, cadF, ciaB, mviN, hecA and iroE, indicating a possible pathogenic nature of this organism. This case demonstrated the importance of the use of agnostic methods for the detection of emerging pathogens in cases of enteric disease with a wide array of gastrointestinal symptoms.

How to achieve accurate blood culture volumes: the BD BACTEC FX blood volume monitoring system as a measuring instrument and educational tool.

Collecting adequate volumes of blood in blood culture bottles is crucial for sensitive detection of bacteremia and fungemia. Tools enabling easy collection of data on the degree of blood culture bottle filling at different hospital departments are an important step toward quality measurement and improvement. In this study, we verified the accuracy of a software tool for the monitoring of blood culture bottle filling developed by Becton Dickinson, BD blood volume monitoring system (BVMS) that was adjusted for use on plastic BACTEC bottles, and evaluated its ease of use in routine practice. In total, 538 negative plastic BD BACTEC Plus Aerobic/F blood culture bottles collected in two secondary care hospitals in Belgium were included in the study. The BVMS software demonstrated good performance, with an acceptable mean difference of - 0.3 mL or - 4.0% between the mean volume estimated by BVMS and the mean weight-based volume. Data (mean blood volume and standard deviation) and figures (box-and-whisker and histogram plots) on blood culture bottle filling are easily acquired. They provide information on the current situation in a hospital (department) and can be used as a tool for quality improvement measurements and follow-up. Caution is required when interpreting BVMS results for hospital wards where a substantial amount of the bottles collected come from patients with hematocrit values < 30%. This study demonstrated that BVMS is a reliable and easy to use tool which facilitates monitoring and coordination of optimization of blood culture bottles filling by the clinical laboratory.

Elderly versus nonelderly patients with invasive aspergillosis in the ICU: a comparison and risk factor analysis for mortality from the AspICU cohort.

Data regarding the epidemiology and diagnosis of invasive aspergillosis in the critically ill population are limited, with data regarding elderly patients (≥75 years old) even scarcer. We aimed to further compare the epidemiology, characteristics and outcome of elderly versus nonelderly critically ill patients with invasive aspergillosis (IA) Prospective, international, multicenter observational study (AspICU) including adult intensive care unit (ICU) patients, with a culture and/or direct examination and/or histopathological sample positive for Aspergillus spp. at any site. We compared clinical characteristics and outcome of IA in ICU patients using two different diagnostic algorithms. Elderly and nonelderly ICU patients with IA differed in a number of characteristics, including comorbidities, clinical features of the disease, mycology testing, and radiological findings. No difference regarding mortality was found. According to the clinical algorithm, elderly patients were more likely to be diagnosed with putative IA. Elderly patients had less diagnostic radiological findings and when these findings were present they were detected late in the disease course. The comparison between elderly survivors and nonsurvivors demonstrated differences in clinical characteristics of the disease, affected sites and supportive therapy needed. All patients who were diagnosed with proven IA died. Increased vigilance combined with active search for mycological laboratory evidence and radiological confirmation are necessary for the timely diagnosis of IA in the elderly patient subset. Although elderly state per se is not a particular risk factor for mortality, a high SOFA score and the decision not to administer antifungal therapy may have an impact on survival of elderly patients.

Drivers and impact of antifungal therapy in critically ill patients with Aspergillus-positive respiratory tract cultures.

Invasive pulmonary aspergillosis (IPA) is an increasingly recognised problem in critically ill patients. Little is known about how intensivists react to an Aspergillus-positive respiratory sample or the efficacy of antifungal therapy (AFT). This study aimed to identify drivers of AFT prescription and diagnostic workup in patients with Aspergillus isolation in respiratory specimens as well as the impact of AFT in these patients. ICU patients with an Aspergillus-positive respiratory sample from the database of a previous observational, multicentre study were analysed. Cases were classified as proven/putative IPA or Aspergillus colonisation. Demographic, microbiological, diagnostic and therapeutic data were collected. Outcome was recorded 12 weeks after Aspergillus isolation. Patients with putative/proven IPA were more likely to receive AFT than colonised patients (78.7% vs. 25.5%; P <0.001). Patients with host factors for invasive fungal disease were more likely to receive AFT (72.5% vs. 37.4%) as were those with multiorgan failure (SOFA score >7) (68.4% vs. 36.9%) (both P <0.001). Once adjusted for disease severity, initiation of AFT did not alter the odds of survival (HR = 1.40, 95% CI 0.89-2.21). Likewise, treatment within 48 h following diagnosis did not change the clinical outcome (75.7% vs. 61.4%; P = 0.63). Treatment decisions appear to be based on diagnostic criteria and underlying disease severity at the time of Aspergillus isolation. IPA in this population has a dire prognosis and AFT is not associated with reduced mortality. This may be explained by delayed diagnosis and an often inevitable death due to advanced multiorgan failure.

Evaluation of direct Etest for antimicrobial susceptibility testing of bacteria isolated from synovial fluid of horses using enrichment bottles.

This study evaluated the Etest for direct antimicrobial susceptibility testing (AST) of bacteria from equine synovial specimens, incubated in BACTEC enrichment bottles. Ninety-four culture-positive broths were inoculated onto agar to directly determine the minimum inhibitory concentrations (MICs) of 13 antimicrobials, using the Etest (direct Etest). Results were compared with those obtained with the agar dilution reference method, the standard Etest, and the disc diffusion method, after subculture and standardisation of the inoculum. For categorical comparison of AST results, MICs were translated into susceptibility categories, using clinical breakpoints. The direct Etest predicted categorical susceptibility/resistance of bacteria from equine synovial fluid with acceptable accuracy (overall categorical agreement, 91%) and was more reliable than the disc diffusion test. The direct Etest was less accurate than the standard Etest for generating MICs ± 1 log dilution relative to the reference method (overall essential agreement, 69% vs. 89%). As the Etest generated a high percentage of inaccuracies with trimethoprim and sulfadiazine, these were less suitable antimicrobial agents for inclusion. In conclusion, the direct Etest reliably predicted the susceptibility of isolates from equine synovial fluid for the tested antimicrobials, except for trimethoprim and sulfadiazine. Since it did not require subculture and preparation of a standardised inoculum, direct Etest results were available at least 24 h earlier than with other methods, which could facilitate the diagnosis of synovial infections. However, when accuracy is prioritised over speed for MIC determination, the standard Etest is preferred over the direct Etest.

Prevalence, Risk Factors, and Clinical Relevance of Fluoroquinolone-Resistant Organisms in Rectal Cultures: Should We Target Antibiotic Prophylaxis Prior to Prostate Biopsy?

The rise of infectious complications after prostate biopsy has been linked to the growing resistance of enterobacteria to fluoroquinolone (FQ) antibiotics. In this review, we investigated the potential benefit of targeted antibiotic prophylaxis based on rectal cultures prior to prostate biopsy. An electronic search for all related literature published in English was performed from April until June 2015 using the MEDLINE and EMBASE databases. Data were obtained regarding the true prevalence of FQ-resistant bacteria in the rectum of patients, the identification of those patients at risk of harbouring FQ-resistant bacteria, the risk of infectious complications after transrectal prostate biopsy in patients with FQ-resistant bacteria, and the effect of targeted prophylaxis. Although there is limited evidence that a targeted approach might be beneficial, we conclude that current studies on the use of rectal cultures in the prebiopsy setting have too many limitations and confounding variables to definitely accept this approach in clinical practice. Whether this methodology is useful in a certain region will greatly depend on local fluoroquinolone-resistance rates.

Evaluation of the BD BACTEC FX blood volume monitoring system as a continuous quality improvement measure.

The yield of blood cultures is proportional to the volume of blood cultured. We evaluated an automatic blood volume monitoring system, recently developed by Becton Dickinson within its BACTEC EpiCenter module, that calculates mean volumes of negative aerobic bottles and generates boxplots and histograms. First, we evaluated the filling degree of 339 aerobic glass blood cultures by calculating the weight-based volume for each bottle. A substantial amount of the bottles (48.3%) were inadequately filled. Evaluation of the accuracy of the monitoring system showed a mean bias of -1.4 mL (-15.4%). Additional evaluation, using the amended software on 287 aerobic blood culture bottles, resulted in an acceptable mean deviation of -0.3 mL (-3.3%). The new software version was also tested on 200 of the recently introduced plastic bottles, which will replace the glass bottles in the near future, showing a mean deviation of +2.8 mL (+26.7%). In conclusion, the mean calculated volumes can be used for the training of a single phlebotomist. However, filling problems appear to be masked when using them for phlebotomist groups or on wards. Here, visual interpretation of boxplots and histograms can serve as a useful tool to observe the spread of the filling degrees and to develop a continuous improvement program. Re-adjustment of the software has proven to be necessary for use with plastic bottles. Due to our findings, BD has developed further adjustments to the software for validated use with plastic bottles, which will be released soon.

Establishing quality control ranges for temocillin following CLSI-M23-A3 guideline.

OBJECTIVES: This study aimed to establish acceptable quality control ranges for temocillin disk diffusion tests and Etest(®) minimal inhibitory concentrations. METHODS: According to Clinical and Laboratory Standards Institute (CLSI) guideline, a Tier 2 quality control study was performed and involves seven laboratories. Each of them tested 10 replicates of two quality control strains (Escherichia coli ATCC 25922 and E. coli ATCC 35218) on three different media lots and, for disk diffusion, two disk lots. RESULTS: Proposed zone diameter quality control ranges were 12-25 mm for E. coli ATCC 25922 and 19-28 mm for E. coli ATCC 35218. Proposed Etest quality control ranges were 3-24 mg/l for E. coli ATCC 25922 and 2-6 mg/l E. coli ATCC 35218. CONCLUSION: Based on our results, we would advise the use of E. coli ATCC 35218 as QC strain for temocillin susceptibility testing and Etest because ranges obtained are narrower than with E. coli ATCC 25922 and do not overlap temocillin breakpoint.

Timely diagnosis of respiratory tract infections: evaluation of the performance of the Respifinder assay compared to the xTAG respiratory viral panel assay.

BACKGROUND: Respiratory tract infections are the most common cause of hospitalization in infants and young children and are typically caused by viral or, less commonly, bacterial pathogens. Existing non-molecular diagnostic methods have several drawbacks such as limited sensitivity, long turn-a-round time and limited number of pathogens that can be detected. OBJECTIVES: Nucleic acid amplification methods can increase sensitivity and enable the initiation of appropriate interventions without delay. Broad-spectrum detection and identification circumvent the use of individual diagnostic DNA or RNA based assays. At present, several commercial assays are available for broad-spectrum detection. STUDY DESIGN: We compared the performance of the xTAG Respiratory Viral Panel (RVP) (Luminex Molecular Diagnostics, Toronto, Canada) with that of the Respifinder (Pathofinder, Maastricht, Netherlands) for 9 external quality assurance (EQA) panels (QCMD, Scotland) consisting of a total of 106 EQA samples. RESULTS: Both the RVP and the Respifinder assay have an excellent specificity. Sensitivity was 33% and 78% for the RVP and the Respifinder assay, respectively. For both assays, sensitivity was low for weak positive samples. DISCUSSION: The results of our study seem to indicate a better sensitivity for the Respifinder. Analysis of patient samples is necessary to evaluate the clinical performance.

Use of blood culture medium enrichment for synovial fluid culture in horses: a comparison of different culture methods.

REASONS FOR PERFORMING STUDY: Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence-based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. OBJECTIVES: To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. METHODS: Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis-centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). RESULTS: Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy-one of 90 samples (79%) were culture-positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. CONCLUSION: Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. POTENTIAL RELEVANCE: The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.

Speed of molecular detection techniques for methicillin-resistant Staphylococcus aureus admission screening in an acute care hospital.

Active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) carriers is considered an essential component of MRSA control strategies in acute care hospitals. Recently, molecular assays for MRSA screening have been proposed with significant reduction of the sample processing time. Using a time analysis model, we investigated the time gain after the introduction of a molecular assay and compared this with a preceding control period, using culture-based techniques. During a four-month period all high risk patients (N=44) and all known MRSA-positive patients readmitted to the hospital (N=41) were screened for MRSA upon admission. In both groups the long pre-analytical phase - time from admission to sampling and transportation of samples to the laboratory - was the determining factor in the entire process. A substantial reduction of the sample processing time was achieved using molecular assays, compared with conventional culture. Due to the long pre-analytical phase, in addition to the high costs associated with polymerase chain reaction (PCR) testing, molecular techniques were not introduced for the admission screenings. In the group of the readmission screenings, however, a fast test result could save a substantial number of unnecessary isolation days, resulting in an economic benefit for the hospital. PCR testing might be of interest for the readmission screenings. In conclusion, local policies for MRSA screening should be investigated before introducing expensive PCR technology.

Prevalence of antibodies to Chlamydia pneumoniae in a Belgian population.

To evaluate the prevalence of antibodies to Chlamydia pneumoniae in a healthy adult Belgian population a study group of 150 medical students was chosen. Sera were collected in the period between March and October 1990 and assessed by the microimmunofluorescence test. Sixty-one per cent were found to have IgG antibodies to C. pneumoniae in a titre greater than or equal to 16, which showed evidence of past infection. Twenty-one per cent had IgA in a titre greater than or equal to 8. In none were antibodies of the IgM fraction detected. The same sera were tested for the presence of antibodies to Chlamydia trachomatis. One hundred and thirty-one sera with no or low titres of antibodies to C. pneumoniae tended to have low or no detectable antibodies to C. trachomatis. Nineteen sera with high (greater than 128) titres of antibodies to C. pneumoniae had IgG antibodies in a titre of greater than or equal to 32 to C. trachomatis. This prevalence (13%) is much higher than one would expect in a population at low risk for C. trachomatis infection. The problem of possible cross-reactions between the three species in the micro-immunofluorescence test is discussed.

Respiratory tract carrier rates of Moraxella (Branhamella) catarrhalis in adults and children and interpretation of the isolation of M. catarrhalis from sputum.

Nonselective media and previously described selective media were used to study the occurrence of Moraxella (Branhamella) catarrhalis in sputum samples of good and poor quality and in samples taken from different sites of the upper respiratory tracts of healthy subjects. It was found that in healthy adults the carrier rate was 5.4%, as opposed to 50.8% in children and 26.5% in people older than 60 years. M. catarrhalis was recovered significantly more often from sputum samples of good quality (5%) than from poor quality samples (0.5%), and when present, it was found mostly in the presence of high inocula. From these data gathered from healthy and diseased subjects, it is concluded that the presence of M. catarrhalis in the sputum of adults is rarely due to oronasopharyngeal contamination of the sputum. Similar findings reported by others are discussed, and the origins of the currently held concept that M. catarrhalis is a common commensal organism of the human upper respiratory tract are traced.

Prevalence of antibodies to Chlamydia pneumoniae in a pediatric hospital population in Belgium.

To evaluate the prevalence of antibodies to Chlamydia pneumoniae in a pediatric hospital population, 207 patients admitted to the pediatric unit of the hospital during the period January to April 1989 were screened. A microimmunofluorescence test was used to measure both Chlamydia pneumoniae specific total antibody and IgM antibody. Fifty-eight (28%) patients were found to have antibodies to Chlamydia pneumoniae. Only one serum contained specific IgM. Analysis of the age specific prevalence of antibody showed a sudden rise in the 10 to 12 year old age group. Cross-reaction in the test with the other Chlamydia species is discussed. It is concluded that the incidence of primary Chlamydia pneumoniae infection during the study period was low, but that the infection occurs in Belgium with about the same prevalence as in other countries.

Serological typing of Branhamella catarrhalis strains on the basis of lipopolysaccharide antigens.

A total of 302 strains of Branhamella catarrhalis from different parts of the world were serologically typed according to their lipopolysaccharide (LPS) antigenicity. For this purpose, an inhibition enzyme-linked immunosorbent assay was developed using the following reagents: antisera raised against whole bacterial suspensions for a panel of 16 serotype strains and LPS prepared from these strains by phenol extraction. Antisera were absorbed with whole bacterial suspensions of the B. catarrhalis strains to be tested. The residual activity of the sera against the homologous LPS was determined by means of an enzyme-linked immunosorbent assay, using microdilution plates coated with LPS. Strains which gave greater than 90% reduction of activity were considered to carry the same LPS type as the serotype strain. It was shown that 93.4% of the strains tested carried one of three possible LPS types. LPS of B. catarrhalis are the rough type and have an apparent Mr of 5,500, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

[Bacteriologic aspects of peritonitis in continuous ambulatory peritoneal dialysis]. / Aspects bactériologiques des péritonites en dialyse péritonéale continue ambulatoire.

Despite the many advantages of chronic ambulatory peritoneal dialysis, peritonitis continues to be a major complication. Gram+ cocci tend to form the major part in the group of causative agents. Various methods have been employed to increase the sensitivity of culture. Data from pertinent studies are compared with our own experiences.

Selective medium for Branhamella catarrhalis with acetazolamide as a specific inhibitor of Neisseria spp.

Several semiselective media for Branhamella catarrhalis have been proposed. These media allow growth of all members of the family Neisseriaceae, and further differentiation is necessary. By addition of 10 micrograms of acetazolamide, a carbonic anhydrase inhibitor, per ml and incubation in air, a medium was created which reduced growth of Neisseria spp. When saliva samples from 178 healthy schoolchildren were screened for the presence of B. catarrhalis, the carrier rate for this organism was estimated to be 48.9% with the selective medium compared with 12.4% when a semiselective medium, which contains only 10 micrograms of vancomycin, 5 micrograms of trimethoprim, and 2 micrograms of amphotericin B per ml, was used and 6.2% when a nonselective blood agar plate was used. The number of Neisseria spp. isolated dropped from 297 on the semiselective agar to 55 on the selective agar.

Creatine determinations as an early marker for the diagnosis of acute myocardial infarction.

In the acute phase of acute myocardial infarction (3-8 h after onset of symptoms) an early transient increase in the creatine concentration of serum, saliva, and especially of urine can be observed. Due to the renal threshold, urine values give a much better discrimination between infarction patients and controls than do serum determination. In some patients secondary peaks of serum and urine creatine concentrations can be seen about 24-36 h after hospital admission. Intramuscular injections of 5.0 mL of a saline solution and muscular trauma interfere with the test, but with angina pectoris interference is absent or limited. Creatine leakage from myocardium is insufficient to explain the observed creatinuria in infarctions, and intact extra-cardiac tissues are believed to be involved in creatine release.

Comparative in vitro activity of the new quinolone fleroxacin (RO 23-6240).

RO 23-6240 (fleroxacin), pefloxacin, augmentin, cefaclor, cef-uroxime, ceftazidime, vancomycin, piperacillin and amikacin were tested against a wide variety of gram-positive and gram-negative bacteria. The MICs of fleroxacin were very similar to those of pefloxacin. Against all the bacterial groups tested, the quinolones compared favorably with the other antimicrobials tested, particularly against the more resistant species such as Corynebacterium group JK and D2 and methicillin-resistant staphylococci.