Search

ABSTRACTCHROMagar Yersinia (CAY) is a new chromogenic medium for the presumptive detection of virulent Yersinia enterocoliticain stools. Based on a comparative analysis of 1,494 consecutive stools from hospitalized patients, CAY was found to be just as sensitive as the reference medium (cefsulodin-irgasan-novobiocin agar) but was significantly more specific and had a very low false-positive rate. CAY reduces the workload (and thus costs) for stool analysis and can therefore be recommended for routine laboratory use.

ABSTRACTThe sensitivities of the Xpert MTB/RIF test and an in-house IS6110-based real-time PCR using TaqMan probes (IS6110-TaqMan assay) for the detection of Mycobacterium tuberculosiscomplex (MTBC) DNA were compared by use of 117 clinical specimens (97 culture positive and 20 culture negative for MTBC) that were frozen in sediment. The 97 clinical specimens included 60 respiratory and 37 nonrespiratory specimens distributed into 36 smear-positive and 61 smear-negative specimens. Among the 97 culture-positive specimens, 4 had rifampin-resistant isolates. Both methods were highly specific and exhibited excellent sensitivity (100%) with smear-positive specimens. The sensitivity of the Xpert MTB/RIF test with the whole smear-negative specimens was more reduced than that of the IS6110-TaqMan assay (48 versus69%, P= 0.005). Both methods exhibited similar sensitivities with smear-negative respiratory specimens, but the Xpert MTB/RIF test had lower sensitivity with smear-negative nonrespiratory specimens than the IS6110-TaqMan assay (37 versus 71%, P= 0.013). Finally, the sensitivities of the Xpert MTB/RIF test and the IS6110-TaqMan assay were 79% and 84%, respectively, with respiratory specimens and 53% and 78%, respectively (P= 0.013), with nonrespiratory specimens. The Xpert MTB/RIF test correctly detected the rifampin resistance in smear-positive specimens but not in the one smear-negative specimen. The Xpert MTB/RIF test is a simple rapid method well adapted to a routine laboratory that appeared to be as sensitive as the IS6110-TaqMan assay with respiratory specimens but less sensitive with paucibacillary specimens, such as smear-negative nonrespiratory specimens.

Growth kinetics, siderophore activity and iron‐regulated bacterial proteins of Acinetobacter baumanniiBM2580 were studied in iron‐restricted and iron‐supplemented chemically defined media. Iron‐regulated outer membrane proteins of 75 kDa and 80 kDa were expressed under iron‐restricted conditions. Cloning and sequencing of the complete iron‐uptake regulatory (fur) gene from A. baumanniiBM2580 is reported for the first time. This gene is preceded by a single autoregulated promoter whose −10 region overlaps the Fur binding site. The open reading frame identified encodes a polypeptide consisting of 145 amino acids. The furgene is followed by a divergent open reading frame coding for the C‐terminus of a putative PilU protein. Sequence analysis indicates that the Fur protein of A. baumanniiwas 63% identical to the Escherichia coliFur protein.

Since the environmental iron concentration has emerged as an important attribute in the expression of bacterial virulence, the purpose of this study was to determine the effects of transferrin, lactoferrin, heme compounds, and inorganic iron sources (ferric and ferrous sulfate) on the growth ofBilophila wadsworthiaand to study its outer membrane composition when grown under these different simulatedin vivoconditions. Lactoferrin, transferrin, hemin and hemoglobin supported full growth of the bacteria in media lacking other iron sources.Bilophila wadsworthiawas also capable of growing in the presence of ferrous and ferric sulfate. Profiles obtained by SDS-PAGE showed two iron-regulated outer membrane proteins (IROMPs) of 190 kDa and 88 kDa. The 190 kDa was susceptible to proteinase K cleavage in whole cells, indicating its exposure at the cell surface. These two major IROMPs were expressed in iron-restricted media supplemented with iron-bound organic sources and repressed by the addition of inorganic iron sources.

A new bronchoscopic-protected catheter brush (BPCB), designed to obtain uncontaminated bronchial secretions, was studied in vitroand in vivo.The device was composed of a standard biopsy brush, protected by a single catheter and occluded with an agar plug. Ejection of the plug was obtained neither by advancing the brush nor by advancing an inner cannula (as in a telescoping catheter brush), but instead, by an air flux, provided by a syringe which was connected to the proximal tip. In the first part of the study the ability of the BPCB to obtain uncontaminated specimens was tested in comparison with the reference telescoping catheter brush (BFW brush 10/70/90, Medi-Tech Corp Watertown, MA). Catheters of each type were successively passed through the inner channel of a bronchofiberscope which was contaminated with Klebsiella pneumonia.After ejection of the distal plug, sampling of bronchial secretions infected with a marker organism (Pseudomonas aeruginosa),was performed with the brush. Culture of brush specimens of each type of catheter grew the marker organism in pure culture and obtained the same amount of bronchial secretions (0.001 ml). The manual vortexing of the brush in the transport medium (Ringer's solution) proved to be as effective as the mechanical vortexing so that transecting of the brush was no longer mandatory. In the second part of this study, paired bronchial samplings from 27 patients were performed using both types of catheters and similar results for both were obtained. In these in vitrostudies, completed by a clinical trial, our single-sheathed, plugged catheter brush proved to be as reliable as the double telescoping catheter brush. However, because of its relatively simple conception, making it easier to use and lower in cost than the double catheter brush, routine use of this sampling device should be considered.

To study the bactericidal activity of β-lactam antibiotics (imipenem, cefepime, cefpirome) alone or in combination with a β-lactamase inhibitor (sulbactam) in the presence or absence of aminoglycoside (amikacin or isepamicin) against Klebsiella pneumoniaestrains producing extended-spectrum β-lactamases (ESBLs).

The protected specimen brush (PSB) with quantitative cultures is one of the most reliable techniques for assessing pneumonia in mechanically ventilated (MV) patients. The need to select a certain lung segment for bronchoscopic sampling is still debated. We investigated whether the results of PSB specimens collected within an area radiographically involved with pneumonia (inv-PSB) differed from the results of PSB specimens collected within a lung area without radiographic abnormalities (non-inv-PSB) in 39 MV patients with suspected pneumonia. The comparison of bacterial titers of inv-PSB and non-inv-PSB cultures did not disclose significant differences. Agreement regarding the diagnosis of pneumonia according to recommended diagnostic threshold was observed in 34 of 39 patients (87.1 percent). These results which are in accordance with the pathophysiology of ventilator-associated pneumonia and histologic studies do not support the need to select a certain lung segment for bronchoscopic sampling in most MV patients with suspected pneumonia.

Objective: To study the bactericidal activity of β‐lactam antibiotics (imipenem, cefepime, cefpirome) alone or in combination with a β‐lactamase inhibitor (sulbactam) in the presence or absence of aminoglycoside (amikacin or isepamicin) against Klebsiella pneumoniaestrains producing extended‐spectrum β‐lactamases (ESBLs).

ABSTRACTWe report the first case of postneurosurgical meningitis due to Psychrobacter sanguinis, identified only by 16S rRNA analysis. Psychrobacterspp. usually live in deep sea environments and cold habitats. Despite a strict questioning of the patient and the medical staff, we did not find the source of this bacterium.

The study through Monte Carlo simulation of -lactam pharmacokineticpharmacodynamic target attainment and determination of subsequent serum concentrations of piperacillin–tazobactam administered through continuous infusion to children treated for fever and neutropenia shows that 400 mgkgday has the highest probability of target attainment against Pseudomonas aeurginosain our oncology ward compared with the standard regimen of 300 mgkgday.

A 5' nuclease PCR assay for detection of the Yersinia pestis plasminogen activator (pla) gene in human respiratory specimens with simulated Y. pestis infection was developed. An internal positive control was added to the reaction mixture in order to detect the presence of PCR inhibitors that are often found in biological samples. The assay was 100% specific for Y. pestis. In the absence of inhibitors, a sensitivity of 10(2) CFU/ml of respiratory fluid was obtained. When inhibitors were present, detection of Y. pestis DNA required a longer sample treatment time and an initial concentration of bacteria of at least 10(4) CFU/ml. The test's total turnaround time was less than 5 h. The assay described here is well suited to the rapid diagnosis of pneumonic plague, the form of plague most likely to result from a bioterrorist attack.

ABSTRACTA new molecular assay detecting toxigenic Clostridium difficile, the BD Max Cdiff (Becton, Dickinson), was evaluated with 360 diarrheal feces samples. It exhibited high sensitivity (97.7%) and specificity (99.7%). The positive (97.7%) and negative (99.7%) predictive values of this test allow an accurate answer within 2 h.

Growth kinetics, siderophore activity and iron-regulated bacterial proteins of Acinetobacter baumannii BM2580 were studied in iron-restricted and iron-supplemented chemically defined media. Iron-regulated outer membrane proteins of 75 kDa and 80 kDa were expressed under iron-restricted conditions. Cloning and sequencing of the complete iron-uptake regulatory (fur) gene from A baumannii BM2580 is reported for the first time. This gene is preceded by a single autoregulated promoter whose −10 region overlaps the Fur binding site. The open reading frame identified encodes a polypeptide consisting of 145 amino acids. The fur gene is followed by a divergent open reading frame coding for the C-terminus of a putative PilU protein. Sequence analysis indicates that the Fur protein of A baumannii was 63% identical to the Escherichia coli Fur protein.

Bactericidal assays of Bacteroides gracilis (six strains) and Bilophila wadsworthia (12 strains) in brucella broth with appropriate supplements were performed by the time-kill kinetic method. Antimicrobial agents tested were ampicillin/sulbactam (final concentrations, 16/8 µg/mL), ticarcillin/clavulanate (128/2 µg/mL), imipenem (8 µg/mL), cefoxitin (32 µg/mL), chloramphenicol (16 µg/mL), clindamycin (4 µg/mL), and metronidazole (16 µg/mL). Although all antimicrobial agents tested inhibited growth of all Bilophila strains during the first 24 hours, bactericidal activity was variable; only metronidazole was uniformly bactericidal. Most strains of Bilophila showed 1–2 log increases in growth at 6 hours with clindamycin and chloramphenicol. With chloramphenicol, some Bilophila strains tested showed regrowth starting at 30 hours. B. gracilis strains were generally more susceptible to all agents tested. Metronidazole, ticarcillin/clavulanate, chloramphenicol, and imipenem were most active. Several strains of B. gracilis were not killed by ampicillin/sulbactam, clindamycin, or cefoxitin. Activity was variable among strains and antimicrobial agents.