Clinical and laboratory evaluation of a real-time PCR for Clostridium difficile toxin A and B genes.

Many laboratories use enzyme immunoassays (EIAs) for the diagnosis of Clostridium difficile infection (CDI). More recently, polymerase chain reaction (PCR)-based diagnosis has been described as a sensitive test. Real-time PCR for the detection of C. difficile toxin A and B genes was evaluated. A prospective evaluation was performed on stool samples from 150 hospitalized adult patients and 141 healthy volunteers. PCR was compared to toxigenic culture (TC), direct cytotoxicity test (CTT), ImmunoCard® Toxin A and B (Meridian Bioscience), and enzyme-linked immunosorbent assay (ELISA) (Vidas). The results were correlated with clinical data using a standardized questionnaire. The diagnostic yield of the PCR was further evaluated after implementation. Using toxigenic culture as the gold standard, the sensitivity and specificity of PCR were 100 and 99.2%, respectively. Patients were categorized as follows: TC/PCR-positive (n = 17) and negative TC (n = 133). The differences in these groups were more frequent use of antibiotics and leukocytosis (p < 0.05). The diagnostic yield of PCR was evaluated during a period of 6 months and showed an increase of positive patients by 50%. PCR for the detection of toxigenic C. difficile has a high sensitivity and can rule out CDI, but cannot differentiate CDI from asymptomatic carriage. Clinicians should be aware of this in order to prevent inappropriate treatment and delay of other diagnostics.

Non-adherence to antimicrobial treatment guidelines results in more broad-spectrum but not more appropriate therapy.

Mortality in patients admitted with sepsis is high and the increasing incidence of infections with multiresistant bacteria is a worldwide problem. Many hospitals have local antimicrobial guidelines to assure effective treatment and limit the use of broad-spectrum antibiotics, thereby reducing the selection of resistant bacteria. We evaluated adherence to the antimicrobial treatment guidelines of our hospital in patients presenting to the emergency department (ED) with sepsis and assessed the in vitro susceptibility of isolated pathogens to the guideline-recommended treatment and the prescribed treatment. We included all adult patients with a known or suspected infection and two or more extended systemic inflammatory response syndrome (SIRS) criteria. Patients who did not receive antimicrobial treatment, presented with infections not included in the guidelines, or had more than one possible focus of infection were excluded. A total of 276 ED visits (262 patients) were included. Guideline-concordant treatment was prescribed in 168 visits (61%). In the case of guideline-disconcordant treatment, 87% was more broad-spectrum than guideline-recommended treatment. A microbiological diagnosis was established in 96 visits (35%). The susceptibility of the pathogens isolated from patients treated with guideline-concordant treatment (n=68) and guideline-disconcordant treatment (n=28) to guideline-recommended treatment (91% versus 89%) and to prescribed treatment (91% versus 93%) was similar (p=0.77 and p=0.79, respectively). In conclusion, non-adherence to the guidelines occurred frequently and resulted in more broad-spectrum empirical therapy. This did not result in a higher rate of susceptibility of the isolated pathogens to the prescribed empirical therapy.

How prompt is prompt in daily practice? Earlier initiation of empirical antibacterial therapy for the febrile neutropenic patient.

With fever being the most common manifestation of early sepsis, clinical practice guidelines emphasise the prompt institution of broad-spectrum antibacterial therapy at its onset. An audit was performed on the haematology ward to determine whether there was any delay in starting antibiotic treatment during neutropenia in clinical patients and to define the main reasons for this. Strategies were developed, implemented and evaluated on short- and long-term implications on the delay in the start of antibacterial therapy. The procedures specified in the protocol for starting empirical antibacterial therapy were audited to assess whether the target for starting therapy within 30 min of fever was achieved. Initial results indicated that two major changes to the protocol were necessary to achieve a reduction in the delay between detection of fever and starting antibacterial therapy. This modified protocol was evaluated 4 months after implementation by means of a consecutive audit. After 3 years, a third audit was performed to determine the long-term implications of the improved protocol. In the initial audit, the mean time interval between the onset of fever and the administration of antibacterial therapy was 75 min. With the modified protocol, the mean time to starting therapy was shortened to 32 min (P < 0.05). Changing the protocol for starting antibacterial therapy allowed nurses to administer the first dose of antibiotic significantly earlier.

Prevalence and molecular mechanism of macrolide resistance in beta-haemolytic streptococci in The Netherlands.

The prevalence of resistance to erythromycin and clindamycin as well as the presence of the resistance genes mef(A), mef(E), erm(A) and erm(B) were determined in 1076 consecutive isolates of beta-haemolytic streptococci of Lancefield groups A (n=219), B (n=562),C (n=58) and G (n=237) collected during 2005 and 2006. The prevalence of macrolide resistance was highest in group C streptococci (6.9%), followed by group B (5.3%), group G (4.6%) and group A (1.4%). Eighty-eight percent of resistance was mediated by erm(A) and erm(B) genes. Macrolide resistance in beta-haemolytic streptococci in The Netherlands is low, but increasing macrolide resistance was observed in group B streptococci.

Decontamination of the digestive tract and oropharynx in ICU patients.

BACKGROUND: Selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) are infection-prevention measures used in the treatment of some patients in intensive care, but reported effects on patient outcome are conflicting. METHODS: We evaluated the effectiveness of SDD and SOD in a crossover study using cluster randomization in 13 intensive care units (ICUs), all in The Netherlands. Patients with an expected duration of intubation of more than 48 hours or an expected ICU stay of more than 72 hours were eligible. In each ICU, three regimens (SDD, SOD, and standard care) were applied in random order over the course of 6 months. Mortality at day 28 was the primary end point. SDD consisted of 4 days of intravenous cefotaxime and topical application of tobramycin, colistin, and amphotericin B in the oropharynx and stomach. SOD consisted of oropharyngeal application only of the same antibiotics. Monthly point-prevalence studies were performed to analyze antibiotic resistance. RESULTS: A total of 5939 patients were enrolled in the study, with 1990 assigned to standard care, 1904 to SOD, and 2045 to SDD; crude mortality in the groups at day 28 was 27.5%, 26.6%, and 26.9%, respectively. In a random-effects logistic-regression model with age, sex, Acute Physiology and Chronic Health Evaluation (APACHE II) score, intubation status, and medical specialty used as covariates, odds ratios for death at day 28 in the SOD and SDD groups, as compared with the standard-care group, were 0.86 (95% confidence interval [CI], 0.74 to 0.99) and 0.83 (95% CI, 0.72 to 0.97), respectively. CONCLUSIONS: In an ICU population in which the mortality rate associated with standard care was 27.5% at day 28, the rate was reduced by an estimated 3.5 percentage points with SDD and by 2.9 percentage points with SOD. (Controlled Clinical Trials number, ISRCTN35176830.)

Performance of two tube coagulase methods for rapid identification of Staphylococcus aureus from blood cultures and their impact on antimicrobial management.

Test parameters and clinical impact of the direct tube coagulase test (DTCT) for rapid identification of Staphylococcus aureus from blood culture were investigated. The sensitivity of the DTCT at 4 h using saline dilution was 96%, compared with 93% using serum separator tubes; specificity was 100% for both methods. Among 32 patients with S. aureus bacteraemia, treatment modifications were based on microbiology results from the primary source of infection in 12 patients, on a Gram's stain from blood culture in seven patients, and on the DTCT in nine patients. The DTCT is a valuable adjunct in the routine microbiology laboratory because of its good performance, technical simplicity and low cost.

Microbiological cultures of allografts of the femoral head just before transplantation.

Allografts of bone from the femoral head are often used in orthopaedic procedures. Although the donated heads are thoroughly tested microscopically before release by the bone bank, some surgeons take additional cultures in the operating theatre before implantation. There is no consensus about the need to take these cultures. We retrospectively assessed the clinical significance of the implantation of positive-cultured bone allografts. The contamination rate at retrieval of the allografts was 6.4% in our bone bank. Intra-operative cultures were taken from 426 femoral head allografts before implantation; 48 (11.3%) had a positive culture. The most frequently encountered micro-organism was coagulase-negative staphylococcus. Deep infection occurred in two of the 48 patients (4.2%). In only one was it likely that the same micro-organism caused the contamination and the subsequent infection. In our study, the rate of infection in patients receiving positive-cultured allografts at implantation was not higher than the overall rate of infection in allograft surgery suggesting that the positive cultures at implantation probably represent contamination and that the taking of additional cultures is not useful.

Ventilator-associated pneumonia caused by Dolosigranulum pigrum.

Dolosigranulum pigrum is an unusual gram-positive catalase-negative coccus. It was isolated, only after prolonged incubation, from bronchial secretions from a patient with ventilator-associated pneumonia. The patient responded well to antimicrobial therapy. Identification was done by 16S rRNA DNA sequence analysis, but it can be done with relatively simple phenotypic tests.

Urosepsis with Actinobaculum schaalii and Aerococcus urinae.

Actinobaculum was isolated from urine only after prolonged incubation in 5% CO(2) after discrepancy between urine Gram stain and initial culture results was observed. Additional patients were diagnosed using this method. The prevalence of Actinobaculum species in urinary tract infections is underestimated since it is not isolated by routine urine culture procedures.

Comparison of the novel quantitative ARMS assay and an enriched PCR-ASO assay for K-ras mutations with conventional cytology on endobiliary brush cytology from 312 consecutive extrahepatic biliary stenoses.

BACKGROUND: Extrahepatic biliary stenosis (EBS) has malignant and benign causes. Patients with EBS are at risk of having or developing malignancy. Accurate diagnostic tests for early detection and surveillance are needed. The sensitivity of biliary cytology for malignancy is low. K-ras mutation analysis on brush cytology is a valuable adjunct, but specificity is low. A quantitative test for K-ras mutations has been developed: the amplification refractory mutation system (ARMS). AIM: To assess the test characteristics and additional value of ARMS in diagnosing the cause of EBS. METHODS: Brush samples from endoscopic retrograde cholangiopancreatography were collected from 312 patients with EBS. K-ras mutation analysis was performed using ARMS-allele specific amplification was coupled with real time fluorescent detection of PCR products. Results were compared with conventional cytology and K-ras mutation analysis using allele specific oligonucleotide (ASO) hybridisation, and evaluated in view of the final diagnosis. RESULTS: The test characteristics of ARMS and ASO largely agreed. Sensitivity for detecting malignancy was 49% and 42%, specificity 93% and 88%, and positive predictive value (PPV) 96% and 91%, respectively. The sensitivity of ARMS and cytology combined was 71%, and PPV was 93%. The specificity of ARMS could be increased to 100% by setting limits for the false positives, but reduced sensitivity from 49% to 43%. CONCLUSIONS: ARMS can be considered supplementary to conventional cytology, and comparable to ASO in diagnosing malignant EBS. A specificity of 100% can be achieved with ARMS, which should be considered in the surveillance of patients at risk for pancreatic cancer.

Aetiology of male urethritis in patients recruited from a population with a high HIV prevalence.

The aetiology of urethritis, the significance of potential pathogens and the relation of urethritis to HIV infection were determined in 335 men (cases) with and 100 men (controls) without urethral symptoms. Urethral swab specimens were tested for different organisms by PCR or by culture for Neisseria gonorrhoeae. The prevalence of N. gonorrhoeae and Chlamydia trachomatis was 52 and 16%, respectively. The potential pathogens: Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis and herpes simplex virus (HSV), were present in 5, 36, 6 and 6% of the cases respectively. M. genitalium was the only potential pathogen associated with microscopic urethritis. After excluding gonococcal infections, U. urealyticum was more frequent in symptomatic patients, while the prevalence of T. vaginalis was similar among cases and controls. These results strongly suggest an a etiological role for M. genitalium in male urethritis, a possible role for U. urealyticum, but not for T. vaginalis. The control group, with 97% genital ulcer disease patients, was not suitable for the investigation of the role of HSV. The sero-prevalence of HIV was 45%. Current infections were not associated with HIV. However, a history of previous urethral discharge was associated with HIV in a multivariate analysis and supported the hypothesis that non-ulcerative sexually transmitted diseases facilitate HIV transmission.

Vaginal tampons as specimen collection device for the molecular diagnosis of non-ulcerative sexually transmitted infections in antenatal clinic attendees.

Self-inserted vaginal tampons for the molecular diagnosis of non-ulcerative STIs were evaluated. Cervical and vaginal swabs, tampons and urines were collected from 185 first-time antenatal clinic attendees. Cultures and nucleic acid amplification assays (NAA) were performed. The sensitivity of PCR on tampons for Trichomonas vaginalis was with 94% (CI 85-98%) significantly higher (P<0.001) than culture (50%, CI 38-62%) or urine (53%, CI 41-65%). Neisseria gonorrhoeae culture had a sensitivity of 64% (CI 36-86%), strand displacement assay (SDA) had a sensitivity of 79% (CI 49-94%) using tampon specimens, 57% (CI 30-81%) using endocervical swabs and 43% (CI 19-70%) using urines. There was no difference in sensitivity of SDA for Chlamydia trachomatis using tampon specimens, urine or endocervical swabs. The specificity approached 100% for all assays on all specimens. NAA on tampons for the detection of T. vaginalis, N. gonorrhoeae and C. trachomatis identified more infections than assays on swabs or urines. This reached statistical significance for T. vaginalis only.

Identification of women at high STD risk among STD clinic attendees: implications for STD programmes.

We showed an association between current infection with a recognized sexually transmitted infection (STI) pathogen and HIV infection in women but not in men with non-ulcerative genital disease. While the accuracy of recognition of male urethritis and genital ulcer syndromes is high, this is significantly less for non-ulcerative STIs in women. The symptoms associated with the latter have a broad differential diagnosis including conditions of a non-STI nature. Local sexually transmitted disease (STD) clinic attendees often comprise patients with and without STIs. We hypothesized that this may be responsible for the association of current STI pathogens and HIV in women. To identify a group of women that would be representative of a true STD clinic population we looked at those with a past history of treated genital ulcers. When we analysed in this subset the association of current STI pathogen and HIV infection, a pattern emerged that was comparable with that in men.

Diagnosis of bacterial vaginosis on self-collected vaginal tampon specimens.

A vaginal tampon specimen was previously shown to be suitable for the molecular diagnosis of non-ulcerative sexually transmitted infections (STIs). Different tampon fluid preparations were evaluated for the diagnosis of bacterial vaginosis (BV). Women with pregnancy related problems were enrolled. Two observers evaluated the different tampon fluid preparations and vaginal smears collected during speculum examination using the Nugent score. Using the Amsel criteria, 21% of the 84 women enrolled were diagnosed with BV. Results of the tampon fluid preparations and vaginal smears showed excellent agreement for both observers (Spearman >0.80). The overall sensitivity and specificity was 91.7% (95% CI: 81.6-96.5) and 79.3% (95% CI: 67.2-87.8), respectively, using the Amsel criteria as reference standard. The tampon provides a specimen for the combined diagnosis of non-ulcerative STIs and BV. This non-invasively collected specimen may facilitate self-initiated testing and population-based studies as well as longitudinal studies that are necessary to gain insight in the epidemiology of BV related to STIs and HIV.

Pancreatic cancer after remote peptic ulcer surgery.

BACKGROUND: Peptic ulcer surgery may carry an increased risk for pancreatic cancer development. Molecular analysis of K-ras codon 12, frequently mutated in conventional pancreatic cancers, might provide insight into the aetiological mechanisms. METHODS: The relative risk of pancreatic cancer was computed by multivariate and person-year analysis in a cohort of 2633 patients who had undergone gastrectomy. Lung cancer risk was analysed as an indirect means of assessing smoking behaviour. K-ras codon 12 mutational analysis was performed on 15 postgastrectomy pancreatic cancers. RESULTS: There was an overall increased risk of pancreatic carcinoma of 1.8 (95% confidence interval, 1.3 to 2.6) five to 59 years postoperatively, which gradually increased to 3.6 at 35 years or more after surgery (chi(2) test for trend, p < 0.05). Multivariate analysis indicated that parameters other than postoperative interval did not influence the risk. Lung cancer risk was significantly increased after surgery, but no time trend was observed. The spectrum and prevalence of K-ras codon 12 mutations were comparable to conventional pancreatic cancer. CONCLUSIONS: Remote partial gastrectomy is associated with an increased risk of pancreatic cancer. Postgastrectomy and non-postgastrectomy pancreatic cancers may share similar aetiological factors, such as smoking. However, the neoplastic process in patients who have undergone gastrectomy appears to be accelerated by factors related to the surgery itself.