Elisabeth Schoutens Serruys

Pseudomonas aeruginosa and Enterobacteriaceae bacteremia after biliary endoscopy: An outbreak investigation using DNA macrorestriction analysis

PURPOSE An outbreak of gram-negative bacteremia in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) was investigated to determine the sources of infection and to control transmission. PATIENTS, METHODS, AND RESULTS The incidence of post-ERCP bacteremia increased from 1.6% (60 of 3,696) procedures to 3.6% (53 of 1,454) procedures (relative risk 2.3, p < 0.0001) after endoscopes were processed in a new automated disinfector. Bacteremia involved nine species of Pseudomonas and Enterobacteriaceae, which were also isolated from processed endoscopes. Seven epidemic strains with highly related genomic macrorestriction profiles each infected 2 or more patients, accounting for 29 (55%) episodes of post-ERCP bacteremia. Strains recovered from endoscopes and from the disinfector were associated with 22 (42%) and 5 (9%) bacteremic episodes respectively. Effective endoscope disinfection was achieved by cleansing and disinfection of a blind channel not processed in the disinfector, additional isopropanol-air flush of all channels, and auto-disinfection of the disinfector. In the following period, the incidence of post-ERCP bacteremia returned to the pre-epidemic rate (1.7%, p = 0.0001). CONCLUSION Bacterial genome fingerprinting by macrorestriction analysis enabled delineation of a multi-strain outbreak of post-ERCP bacteremia. Cross-contamination, and to a lesser extent, common-source contamination, appeared related to inadequate disinfection of endoscopes processed in an automated disinfector.

Risk factors for septicemia following endoscopic biliary stenting

The purpose of this study was to identify patients who were more likely to experience septicemia after endoscopic biliary drainage. In an attempt to determine the relative importance of each risk factor and their possible interdependancy to more precisely identify high-risk patients and to deduce some guidelines for prevention, a discriminant regression analysis of risk factors for septicemia was used. Clinical, biological, and radiological data of 34 consecutive patients who experienced septicemia within 3 days after endoscopic biliary stenting were reviewed retrospectively and compared with data of a group of 71 patients without any septic complication. If only data available before the procedure were used in the discriminant analysis, prior cholangitis and leucocytosis appeared as significant risk factors, but the linear combination of these data could not predict septicemia in 50% of cases. When information concerning the quality of drainage after the procedure was introduced into the analysis, 91% of the septicemic patients were identified, and other expected risk factors such as the nature of the stricture, the type of drainage, or prior cholangitis and leukocytosis had no or marginal predictive values. Patients referred from centers where duodenoscopes might have been poorly disinfected appeared to be at higher risk for Pseudomonas aeruginosa septicemia. These results emphasize the crucial role of the quality of drainage as a risk for septicemia. Regarding the prevention of infection, it is concluded from this study that (a) pure diagnostic endoscopic retrograde cholangiopancreatography should be avoided in obstructed patients if drainage cannot be performed during the same procedure; (b) drainage should be as complete as possible; (c) antibiotics should be administered before ERCP to every patient with suspected obstructive jaundice and should cover P. aeruginosa if local epidemiological data suggest that there is a problem with disinfection of the endoscopes; and (d) the quality of drainage should guide the duration of antibiotic prophylaxis.

Rapid detection of tuberculous and non-tuberculous mycobacteria by polymerase chain reaction amplification of a 162 bp DNA fragment from antigen 85.

A polymerase chain reaction (PCR) assay was developed for detection of mycobacteria using amplification of a 162 bp region of the genes coding for the mycobacterial antigen 85 complex. Strains belonging to theMycobacterium tuberculosis complex were further differentiated from non-tuberculous mycobacteria by hybridization of the PCR derived Southern blot with an internal oligonucleotide probe and washing under stringent conditions. The method allowed rapid and sensitive detection of mycobacterial DNA in uncultured clinical samples. PCR results obtained forMycobacterium tuberculosis in 206 specimens from 180 untreated patients gave a sensitivity of 93.9% and a specificity of 94.3% compared with the culture. PCR detected DNA fromMycobacterium tuberculosis in seven samples from patients with clinically evident tuberculosis in whom culture was negative. The results suggest that this PCR assay could be used for early and specific diagnosis of tuberculosis.

Rapid Simple and Nested Polymerase Chain Reaction for the Diagnosis of Pneumocystis carinii pneumonia

We have developed a rapid and easy extraction procedure for polymerase chain reaction (PCR) protocols. Using this simplified step, we evaluated the sensitivity and the specificity of a simple PCR using the primers of Wakefield et al, and of a nested PCR, using new internal primers selected by us, in a total of 89 bronochoalveolar lavage (BAL) fluid samples from 43 immunosuppressed patients. In 13 patients, Pneumocystis carinii pneumonia (PCP) was diagnosed by immunofluorescent antibody (IFA) staining performed on BAL cells cytospun on microscope slides. In seven of these patients we attempted to estimate the post-treatment persistence of P. carinii in BAL, by PCR. After a rapid 2-h extraction procedure, simple and nested PCR were positive in all cases of PCP. SImple and nested PCR both had a 100% sensitivity and a 98 and 84% specificity respectively, compared to IFA. After completion of treatment, BAL liquids from asymptomatic patients were no longer positive by both PCR techniques, whereas the BAL fluid of a patient who was still symptomatic was positive by simple and nested PCR. In follow-up BAL fluids of patients with proven PCP, persistence of P. carinii was detected for a longer period by nested PCR than by simple PCR. Simple PCR is a very rapid and sensitive assay for the diagnosis of PCP in BAL fluid and gives clear-cut results in the case of doubtful IFA staining results. Nested PCR seems to improve the sensitivity of the detection of P. carinii in BAL fluid, but the clinical relevance of a positive result remains to be investigated..

Vascular graft infection caused by Aspergillus species: case report and review of the literature.

We report an unusual case of vascular graft infection caused by Aspergillus fumigatus that began with a false aneurysm, major arterial emboli, and septic arthritis. Successful treatment included resection of the infected graft, restoration of circulation by extraanatomic bypass, and administration of amphotericin B and itraconazole, a new antifungal agent. Graft infection in the case reported herein most likely occurred during surgery and took place during an insidious outbreak of postoperative infection.

Prevotella bivia as an unusual cause of endocarditis.

A case of monomicrobial endocarditis due toPrevotella bivia in a 60-year-old man without previous cardiac lesions is reported. The extremely indolent course with multiple systemic emboli as the only clinical manifestation occurring at least seven months before diagnosis and the persistently negative blood cultures were remarkable features of this case. The incidence, clinical characteristics, treatment and outcome of published cases of infective endocarditis due to anaerobic bacteria are briefly reviewed.

In vitro activity of commonly used oral antimicrobial agents against community isolates of respiratory pathogens.

The in vitro activity of ampicillin, amoxicillin/clavulanate, cefadroxil, cefaclor, cefuroxime (axetil), co-trimoxazole, doxycycline, ciprofloxacin, ofloxacin, erythromycin, and roxithromycin was tested against unselected isolates of S. pneumoniae (70), H. influenzae (93), and M. catarrhalis (46), cultured from clinically significant sputum samples of general practice patients. All isolates of S. pneumoniae were highly susceptible to ampicillin; cefadroxil and cefaclor were markedly less active on a weight basis; resistance was only observed with co-trimoxazole (4.3%), doxycycline (5.7%), and erythromycin (2.9%); however, ciprofloxacin and ofloxacin showed median MICs (MIC50), that were only one dilution below breakpoint. Beta-lactamase was detected in 14.0% of H. influenzae isolates; all isolates were susceptible to amoxicillin/clavulanate, cefaclor, and cefuroxime (axetil), although MICs were generally higher for cefaclor; the highest activity was exhibited by ciprofloxacin and ofloxacin; apart from cefadroxil, erythromycin, and roxithromycin, that showed only marginal activity, resistance was observed with co-trimoxazole (4.3%) and doxycycline (1.1%). All (including 71.7% of beta-lactamase producing) isolates of M. catarrhalis were susceptible to amoxicillin/clavulanate, cefaclor and cefuroxime (axetil), although MICs were markedly lower for amoxicillin/clavulanate; ciprofloxacin and ofloxacin showed the lowest MICs; resistance was only observed with cefadroxil (2.2%). In conclusion, the antimicrobial agents showing the most uniformly high in vitro activity against the 3 common community respiratory pathogens tested in the present study, were amoxicillin/clavulanate and, to a lesser extent, cefuroxime (axetil).

Evaluation of Gas-Liquid Chromatography (GLC) for Rapid Detection of Clostridium Difficile in Fecal Specimens.

Clostridium difficile intestinal infection is a major nosocomial hazard in patients receiving antimicrobial therapy. Rationale for rapid diagnosis include lifesaving antimicrobial therapy in patients with severe colitis and early isolation measures for transmission control. We have therefore analysed the sensitivity, specificity and predictive value of GLC identification of isocaproic acid in diarrheic stools from adult hospitalized patients in comparison with selective fecal culture on Cycloserine Cefoxitin Fructose Agar. During the study period, the prevalence of positive culture for C. difficile was 38/595 fecal specimens (6.4%). Compared with culture, GLC had a sensitivity of 24/38 (63%) and a specificity of 524/557 (94%). The predictive value of a positive GLC was 24/57 (42%) and of a negative GLC was 524/538 (97%). Measurement of the isocaproic acid peak height did not allow determination of a cutt-off value improving the test accuracy. The sensitivity of detection of isocaproic acid in stools by GLC is too low to be used as screening test for C. difficile infection. However, in a low prevalence population, a positive GLC test increased the pre-test probability of infection sevenfold.