A total of 300 recent blood stream and pneumonia isolates of
Pseudomonas aeruginosa from 32 different medical centers in the United States were used to assess the accuracy of the Vitek System ...(GNS-107 card) for cefepime, a new “fourth-generation” cephalosporin. The Vitek System test result was compared to the consensus of the three other methods (reference broth microdilution, disk diffusion, Etest (AB BIODISK, Solna, Sweden)), and 271 of 300 consensus category of susceptibility sets were unanimous. The Vitek System produced a 25.3% error rate (5.3% false resistance, 20.0% minor errors). A consistent trend toward higher MIC results with the Vitek System was observed that produced a 15.3 to 21.3% lower susceptible rate compared with the other susceptibility test methods. The consensus cefepime resistance rate was only 4.3% compared to 14.0% for the Vitek GNS-107 card. The error was reproducible on triplicate repeat testing. These results indicate an unacceptable rate of false resistance being produced by the Vitek System when testing cefepime against
P. aeruginosa strains. Alternative methods are suggested for this broad-spectrum antipseudomonal cephalosporin.
We compared EUCAST and CLSI antifungal susceptibility testing methods for itraconazole, posaconazole, and voriconazole by testing 245 Aspergillus clinical isolates. The essential agreement (EA) ...between methods was excellent: 100% (itraconazole), 98.4% (posaconazole), and 99.6% (voriconazole) assessing EA at ±2 dilutions and 99.6% (itraconazole), 87.7% (posaconazole), and 96.3% (voriconazole) at ±1 dilution.
Nontuberculous mycobacteria (NTMs) are environmental microorganisms that can cause infections in humans, primarily in the lung and soft tissue. The prevalence of NTM-associated diseases is increasing ...in the United States. Exposure to NTMs occurs primarily through human interactions with water (especially aerosolized). Potable water from sites across the U.S. was collected to investigate the presence of NTM. Water from 68 taps was sampled 4 times over the course of 2 years. In total, 272 water samples were examined for NTM using a membrane filtration, culture method. Identification of NTM isolates was accomplished by polymerase chain reaction (PCR) amplification of the 16S rRNA and hsp65 genes. NTMs were detected in 78% of the water samples. The NTM species detected most frequently were: Mycobacterium mucogenicum (52%), Mycobacterium avium (30%), and Mycobacterium gordonae (25%). Of the taps that were repeatedly positive for NTMs, the species M. avium, M. mucogenicum, and Mycobacterium abscessus were found to persist most frequently. This study also observed statistically significant higher levels of NTM in chloraminated water than in chlorinated water.
Candida species are the fourth most frequent cause of nosocomial bloodstream infections, and 25%–50% occur in critical care units. During an 18-month prospective study period, all patients admitted ...for ⩾72 hours to the surgical (SICUs) or neonatal intensive care units (NICUs) at each of the participant institutions were followed daily. Among 4,276 patients admitted to the seven SICUs in six centers, there were 42 nosocomial bloodstream infections due to Candida species (9.8/1,000 admissions; 0.99/1,000 patient-days). Of 2,847 babies admitted to the six NICUs, 35 acquired a nosocomial bloodstream infection due to Candida species (12.3/1,000 admissions; 0.64/1,000 patient-days). The following were the most commonly isolated Candida species causing bloodstream infections in the SICU: Candida albicans, 48%; Candida glabrata, 24%; Candida tropicalis, 19%; Candida parapsilosis, 7%; Candida species not otherwise specified, 2%. In the NICU the distribution was as follows: C. albicans, 63%; C. glabrata, 6%; C. parapsilosis, 29%; other, 3%. Of the patients, 30%–50% developed incidental stool colonization, 23% of SICU patients developed incidental urine colonization, and one-third of SICU health care workers' hands were positive for Candida species.
Candida tropicalis has been known to be a major cause of invasive
Candida infection. Numerous reports have documented
C. tropicalis as the most common species of
Candida other than
C. albicans. The ...epidemiology and antifungal susceptibility of
C. tropicalis are poorly defined. A series of 89 clinical isolates of
C. tropicalis from 56 patients hospitalized at seven different U.S. medical centers were analyzed by restriction endonuclease analysis of genomic DNA (REAG) using the restriction enzymes Sfi
I and BssH
II followed by pulsed-field gel electrophoresis (PFGE). The MICs of the isolates for amphotericin B, 5-fluorocytosine (5FC), fluconazole, itraconazole, and D0870 were determined by microbroth dilution testing. A total of 49 different DNA types were identified among the 89 isolates. Generally, each DNA type represented an individual patient, and serial isolates from the same patient were the same DNA type. Small clusters of patients infected with the same DNA type of
C. tropicalis suggested possible nosocomial transmission. The MICs of the various antifungal agents were amphotericin B 0.5 to 2.0 μg/ml (MIC
90 = 2.0 μg/ml), 5FC 0.25 to 1.0 μg/ml (MIC
90 = 0.5 μg/ml), fluconazole 0.25 to 8.0 μg/ml (MIC
90 = 1.0 μg/ml), itraconazole 0.03 to 1.0 μg/ml (MIC
90 = 0.5 μg/ml), and D0870 0.007 to 0.12 μg/ml (MIC
90 = 0.03 μg/ml). These data support previous observations that infections caused by
C. tropicalis frequently originate from the patient's own endogenous flora. Clusters of a single strain in individual hospitals also suggests that limited nosocomial transmission may occur.
Fluoroquinolones, especially the newer agents, have an increased role in the management of respiratory tract infections worldwide. In the SENTRY Antimicrobial Surveillance Program for the ...Asia-Pacific Region for 1998 and 1999, 630
Streptococcus pneumoniae, 583
Hemophilus influenzae and 274
Moraxella catarrhalis isolates were examined to determine the comparative activity of the new fluoroquinolone, gatifloxacin, compared with those of ciprofloxacin, levofloxacin and trovafloxacin. Gatifloxacin was highly active against all three species. Decreased susceptibility (MIC ≥2 μg/mL) to gatifloxacin was noted in only seven strains of
S. pneumoniae (3 of which were resistant); in three strains of
H. influenzae (MIC ≥ 0.12 μg/mL), and 2
M. catarrhalis (MIC > 2 μg/mL).
Modern epidemiology studies now require that nosocomial pathogens be characterized to the subspecies level whenever possible to better define infectious processes and modes of transmission. In ...general, if isolates are classified as different by at least one molecular typing method, they may be assumed to represent different strains and to reflect independent infections. If the isolates are the same, it may be assumed that cross infection has occurred or that the patients were infected by exposure to a common source. Typing methods may also be used to address clinical problems related to distinguishing reinfection versus relapse of an infection, and to examine the development of antifungal resistance among fungal pathogens during the course of antifungal therapy. Determining DNA fingerprints of sequential isolates from patients undergoing antifungal therapy has been useful in demonstrating the potential for the development of antifungal resistance in previously susceptible strains and for detecting the substitution of a more resistant strain for a more susceptible strain in the face of intense antimicrobial pressure. In order to be useful as an epidemiological typing method, a DNA fingerprinting system must effectively distinguish between genetically unrelated strains, identify the same strain in separate samples, and reflect genetic relatedness or unrelatedness (genetic distance) among strains.
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