Detection of Clostridium difficile toxins A and B in stools by Premier Cytoclone A؉B enzyme immunoassay (EIA) was compared with detection by stool culture for C. difficile followed by detection of toxigenic isolates using the same EIA. Chart reviews were performed to evaluate the likelihood of C. difficile-associated diarrhea and colitis (CADC) for all patients with at least one positive toxin assay. While the toxins were detected in 58 of 85 consecutive CADC patients by both assays, CADC in 5 patients was detected only by stool toxin assay, and in 22 patients CADC was detected only by toxigenic culture. Our results suggest that for laboratories using a rapid toxin A؉B EIA, direct toxin detection in stools should be combined with toxigenic culture in cases in which there is a negative stool toxin assay.Clostridium difficile causes mainly nosocomial enteric diseases that range from antibiotic-associated diarrhea to pseudomembranous colitis (PMC) (13). Various laboratory methods may be used to diagnose C. difficile-associated diarrhea and colitis (CADC), but the two main approaches currently available are based on detection of toxin A, toxin B, or both in stool specimens and detection of toxigenic strains after stool culture (toxigenic culture) (6,7,11,19). Although different data support the idea that both methods are necessary for optimal diagnosis of CADC (4, 5, 10-12, 18, 19, 21), the value of toxigenic culture is still a topic of debate (6,20). Toxin A-negative, toxin B-positive, and both toxin A-positive and toxin B-negative C. difficile strains may be pathogenic in humans (1,8,15). Thus, methods used for toxin detection in stools and/or detection of toxigenic strains should ideally detect both toxins (14). For toxigenic culture, such an approach has been realized until now in only a few studies using both a toxin A enzyme immunoassay (EIA) and a cytotoxin assay (4, 10, 21). The cytotoxin assay is considered the most sensitive method for detecting toxin B in stools, but it requires the use of cell culture and antitoxin and is not well standardized. This limits its use in many clinical laboratories. Commercially available rapid EIAs that detect both toxins have been shown to accurately detect toxins in stools (3,9,16,17) and may represent a more practical method among diagnostic strategies that combine detection of toxins in stools with toxigenic culture.The aim of this study was to evaluate the usefulness of such a test, the Premier Cytoclone AϩB EIA (Meridian Diagnostics, Inc., Cincinnati, Ohio), in identifying CADC patients by stool toxin assay and/or toxigenic culture.A total of 1,104 consecutive diarrheal stool samples obtained from 720 patients in our hospital was sent to our laboratory with a request for C. difficile toxin detection and tested by all assays in parallel. Specimens were processed immediately or stored at 4°C for Յ48 h prior to assay. Part of each sample was set aside and kept at Ϫ80°C for later follow-up testing if required. Toxins were detected in stools by the Premier Cytoclone AϩB EIA...
Pasteurella multocida is a commensal of the upper respiratory tract of various animals. The spectrum of human diseases caused by P. multocida varies from soft-tissue infections following bites and scratches to systemic infections, including respiratory tract infections resulting from airborne contamination and/or chronic carriage. Antimicrobial resistance of Pasteurella strains originating from animals has been reported for many years. Human P. multocida isolates are usually susceptible to penicillins. We report a case in which a strain of b-lactamase-producing P. multocida was isolated from a lung abscess specimen and review related cases.A 75-year-old woman with chronic bronchitis was hospitalized with fever (temperature, 40ЊC), weight loss, increased productive cough, and dyspnea. A chest x-ray was unremarkable, whereas the WBC count was 13,900/mm 3 (89% neutrophils) and the one-hour erythrocyte sedimentation rate was 63 mm/h. The patient was treated for 8 days with intravenous amoxicillin (1.5 g/d). Because of persistent signs of infection, a new chest radiograph was obtained, which showed a left lung abscess; the abscess was confirmed by CT. Culture of specimens obtained by bronchoalveolar lavage yielded P. multocida subspecies multocida (10 5 cfu/mL) and Haemophilus parainfluenzae (10 3 cfu/ mL).Production of b-lactamase by both isolates was detected by a chromogenic test using nitrocefin-impregnated disk and the synergic effect between clavulanate and amoxicillin by disk diffusion testing. Minimum inhibitory concentrations of amoxicillin and amoxicillin/clavulanate for the P. multocida strain were of 8 and 0.25 mg/mL, respectively. Consequently, amoxicillin was changed to intravenous amoxicillin/clavulanic acid (3 g/d). A favorable outcome was achieved, and the patient was discharged from the hospital; medication at the time of discharge was oral amoxicillin/clavulanic acid for 2 months. Our patient had no known exposure to animals other than her cat. Two different strains of P. multocida (subspecies multocida and septica) were isolated from the cat's saliva, but none of them was found to produce b-lactamase.A MEDLINE search of the literature revealed only 4 welldocumented cases of human infections due to penicillin-resistant P. multocida [1][2][3][4]. All 4 cases were respiratory tract infections. The principal features of these cases along with our case are presented in table 1. The respiratory tract is the most common site of pasteurella infections after soft tissues [5]. Previous studies have shown that impaired pulmonary defenses,
In vitro or animal models have been used to investigate the pathogenesis of Helicobacter pylori infection. However, extrapolation to humans of results obtained with these heterologous models remains difficult. We have developed a new model for the study of H. pylori infection that uses human entire embryonic stomachs engrafted in nude mice. At 80 days after implantation, 22 of these xenografts, which exhibited a mature gastric epithelium, were inoculated with 107 to 108 CFU of eitherH. pylori LB1, a freshly isolated H. pyloristrain (n = 12), or H. pylori ATCC 49503 (n = 10). After 12-week examination, H. pylori LB1 persistently colonized the antrum of all inoculated grafts, as assessed by culture (mucus and mucosa), immunohistochemistry (mucosa), and a rapid urease test (mucus). H. pylori ATCC 49503, either before or after in vivo passage, permitted only a transient 2-week colonization in one of the five inoculated grafts in both groups. Colonization was always associated with an increase of gastric juice pH. A mild neutrophil infiltration of the gastric mucosa was noted solely in infected grafts. Transmission electron microscopy showed adherence of H. pylori organisms to epithelial cell surface. In six animals, intracytoplasmic location of this bacterium was observed in the antrum or the fundus. These results allow us to propose this model as a new ex vivo model for the study of specificH. pylori-gastric cell interactions.
Among cases of bacteremia, 27% were caused by PNSP, but this level varies according to the counties and the age of the patients. Infection-related mortality was high, but there was no increase related to penicillin G non-susceptibility of the infecting strain.
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