Biomedical subjects

M A Pfaller

Publications and source records attributed to M A Pfaller.

At least 163 records · Page 9Linked to original sources

PubMed1999

Comparative evaluation of an automated ribotyping instrument versus pulsed-field gel electrophoresis for epidemiological investigation of clinical isolates of bacteria.

A collection of bacterial isolates were typed using the Ribo-Printer Microbial Characterization System (Qualicon, Wilmington, DE, USA), an automated ribotyping system, and pulsed-field gel electrophoresis (PFGE). Grouping patterns, discrimination, and typeability were compared. The collection consisted of 411 isolates of bacteria from 32 medical centers. The isolates included a total of 18 species (both Gram-positive and Gram-negative), covering the range of concern to a laboratory performing epidemiological investigations. The patterns of groups obtained by both typing systems were similar for all species examined. Ribotyping provided less discrimination than PFGE, especially for Serratia marcescens, and Pseudomonas aeruginosa. All strains were typed by the Ribo-Printer, but 2.75% were not typeable by PFGE. The Ribo-Printer has proven to be a valuable primary typing method for a high-volume laboratory, even for those species for which it provides a lesser degree of discrimination than PFGE.

Bacteria↗

PubMed1999

International surveillance of blood stream infections due to Candida species in the European SENTRY Program: species distribution and antifungal susceptibility including the investigational triazole and echinocandin agents. SENTRY Participant Group (Europe).

The SENTRY Antimicrobial Surveillance Program, an international study of blood stream infections (BSIs), detected 170 episodes of candidemia in 20 European medical centers (13 nations) between January and December, 1997. Twenty-three percent of the candidal BSI occurred in patients hospitalized in an intensive care unit, 21% in patients in an internal medicine service, 13% in patients in a surgical service, and 9% in patients in an oncology service. Overall, 53% of the BSI were attributable to Candida albicans followed in prevalence by C. parapsilosis (21%), C. glabrata (12%), C. tropicalis (6%), C. famata (2%), C. krusei (1%), and C. inconspicua (1%). As observed previously in Canada and Latin America, C. parapsilosis and not C. glabrata, was the most common non-albicans species causing yeast BSI in Europe. The proportion of these candidemias attributable to C. albicans varied widely from 0-100% among the 20 European centers. Among the different species of Candida, resistance to fluconazole (MIC, > or = 64 micrograms/mL) and itraconazole (MIC, > or = 1.0 microgram/mL) was observed with C. glabrata and C. krusei and was observed more rarely among other species (e.g., C. inconspicua). Isolates of C. albicans, C. parapsilosis, C. tropicalis, and C. guilliermondii were all highly susceptible to both fluconazole and itraconazole. Furthermore, the investigational triazoles (BMS-207147, Sch 56592, and voriconazole) and an echinocandin (MK-0991) all demonstrated potent in vitro activity (MIC90s, 0.5, 0.5, 1.0, and 2.0 micrograms/mL, respectively) against these isolates. Continued surveillance at an international level will be important to monitor trends in species distribution and antifungal susceptibility among invasive strains of Candida.

Antifungal Agents↗

PubMed1999

Colony morphology of Candida spp. as a guide to species identification.

The presence of colony projections, often referred to as "feet," have typically been considered a characteristic of Candida albicans. In the current study that examined the colony morphology of numerous different species of Candida, several clinical isolates of Candida tropicalis and Candida krusei were also noted to produce "feet." The medium and growth conditions under which colony projections were produced by these species were characterized.

Candida↗

PubMed1999

Multicenter evaluation of the antimicrobial activity for seven broad-spectrum beta-lactams in Turkey using the Etest method. Turkish Antimicrobial Resistance Study Group.

From March through July 1997, a nine laboratory surveillance project was initiated in Turkey to monitor the potency and spectrum of seven broad-spectrum antimicrobial agents (cefepime, ceftazidime, cefotaxime, imipenem, aztreonam, cefoperazone/sulbactam, and ticarcillin/clavulanate) tested against approximately 100 organisms (average 82; range 70 to 95 isolates) per participant center (736 strains). Eleven groups of organisms were tested by the Etest method (AB BIODISK, Solna, Sweden) with results validated by concurrent quality control strain analysis. Results from all centers were tabulated and 91.1% of quality assurance tests were within ranges recommended by the National Committee for Clinical Laboratory Standards. Among the seven beta-lactam-class drugs tested, imipenem and cefepime were the most active beta-lactams tested against all isolates. Overall, the rank order of susceptibility of the seven agents was imipenem > cefepime > cefoperazone/sulbactam > ceftazidime > cefotaxime > aztreonam > ticarcillin/clavulanate. Both cefepime and imipenem were active against ceftazidime-resistant strains of Enterobacteriaceae as well as against Streptococcus spp. and oxacillin-susceptible Staphylococcus aureus. Resistance phenotypes consistent with extended spectrum beta-lactamases were documented among Escherichia coli and Klebsiella spp., and profiles consistent with stably derepressed Bush-Jacoby-Mederios group 1 (Amp C) cephalosporinases were common among Enterobacter spp., Citrobacter spp., and Serratia spp. These data should be used to guide empiric therapy with beta-lactams in Turkey, and additionally will provide a reference statistical baseline to which future national studies of drugs in this class can be compared.

Anti-Bacterial Agents↗

PubMed1999

Multicenter evaluation of the antimicrobial activity for six broad-spectrum beta-lactams in Venezuela: comparison of data from 1997 and 1998 using the Etest method. Venezuelan Antimicrobial Resistance Study Group.

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 502 bacteria in seven Venezuelan hospital laboratories. These data were compared with results of a similar study performed in 1997. The organisms tested included 309 recent clinical isolates of Enterobacteriaceae, 70 Pseudomonas aeruginosa, 54 Acinetobacter species, and 69 oxacillin-susceptible Staphylococcus aureus. Extended spectrum beta-lactamase production was noted among 30% of Klebsiella pneumoniae isolates. Hyperproduction of Amp C cephalosporinase producing resistance to ceftazidime and cefotaxime was observed with 10 to 37% of isolates of Enterobacter spp., Serratia spp., and Citrobacter freundii. The overall rank order of activity of the six beta-lactams tested in this study against all clinical isolates was imipenem (96.6% susceptible) > cefepime (90.4%) > piperacillin/tazobactam (85.7%) > ceftazidime (73.5%) > cefotaxime (70.5%) > piperacillin (55.0%). These findings were very similar to those reported for 1997.

Anti-Bacterial Agents↗

PubMed1999

Multicenter evaluation of antimicrobial resistance to six broad-spectrum beta-lactams in Colombia: comparison of data from 1997 and 1998 using the Etest method. The Colombian Antimicrobial Resistance Study Group.

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 823 bacteria in 11 Colombian hospital laboratories. These data were compared with results of a similar study conducted in 1997. The organisms tested included 532 recent clinical isolates of Enterobacteriaceae, 108 Pseudomonas aeruginosa, 94 Acinetobacter species, and 89 oxacillin-susceptible Staphylococcus aureus. Extended-spectrum beta-lactamase production was noted among 27.8 to 33.9% of Escherichia coli isolates and 41.7 to 46.7% of Klebsiella spp. isolates. Hyperproduction of Amp C cephalosporinases was observed with 10.5 to 31.4% of isolates of Enterobacter spp., Serratia spp., and Citrobacter spp. An increase in resistance to all of the beta-lactams was observed among Enterobacteriaceae, Acinetobacter spp. and P. aeruginosa when 1998 results were compared with those obtained in 1997. The overall rank order of activity of the six beta-lactams tested in 1998 versus all clinical isolates was imipenem (93.2% susceptible) > cefoperazone/sulbactam (84.1%) > cefepime (80.9%) > ceftazidime (70.7%) > aztreonam (65.7%) > cefotaxime (65.6%). In contrast, the rank order of these same agents tested against a similar collection of Colombian isolates in 1997 was imipenem (96.6% susceptible) > cefepime (93.6%) > cefoperazone/sulbactam (90.5%) > cefotaxime (74.9%) > aztreonam (74.3%) > ceftazidime (73.2%).

Colombia↗

PubMed1999

Development of in vitro susceptibility testing methods for gemifloxacin (formerly LB20304a or SB-265805), an investigational fluoronaphthyridone.

Potent investigational fluoroquinolones require convenient, but accurate, diagnostic tests for initially applied clinical trials. For this purpose, gemifloxacin (formerly SB-265805, LB20304a) was tested by the reference dilution tests and standardized disk diffusion methods of the National Committee for Clinical Laboratory Standards (NCCLS) to establish interpretive criteria. For rapid-growing pathogens, 986 organisms were tested by broth microdilution MIC, and 5- and 10-microgram disk diffusion tests. Correlation (r) between 5- and 10-microgram disk zone diameters was 0.99 (y = -0.12 to 0.99x) and the preferred 5-microgram disk zone/MIC scattergram produced a regression of y = 14.8 to 0.41x (r = 0.93). At potential pharmacodynamics (Cmax = 1.3 micrograms/mL for 320 mg dose) validated breakpoints of < or = 0.5 microgram/mL for susceptible and > or = 2 micrograms/mL for resistant, correlate zones of > or = 17 mm and < or = 13 mm produced rare serious interpretive errors (0.1%) and 96.7% absolute categorical agreement. For 304 Streptococcus pneumoniae and 305 strains of other streptococci, the same breakpoints produced 100 and 99.1% categorical accuracy even when testing levofloxacin-resistant (MIC, > or = 4 micrograms/mL) strains. Interpretive breakpoints were proposed for Hemophilus influenzae (300 strains tested), with complete correlation between tests. Etest (AB BIODISK, Solna, Sweden) was compared in all experiments with the fastidious species and showed a trend toward higher values (twofold). Gemifloxacin in vitro susceptibility test methods seem to be accurate and with very acceptable intermethod agreement, supported by previously reported functional quality control guidelines.

Anti-Infective Agents↗

PubMed1999

The epidemiology of candidemia in two United States cities: results of a population-based active surveillance.

We conducted prospective, active population-based surveillance for candidemia (defined as any Candida species isolated from blood) in Atlanta and San Francisco (total population, 5.34 million) during 1992-1993. The average annual incidence of candidemia at both sites was 8 per 100,000 population. The highest incidence (75 per 100,000) occurred among infants </=1 year old. In 19% of patients, candidemia developed prior to or on the day of admission. Underlying medical conditions included cancer (26%), abdominal surgery (14%), diabetes mellitus (13%), and human immunodeficiency virus infection (10%). In 47% of cases, species of Candida other than Candida albicans were isolated, most commonly Candida parapsilosis, Candida glabrata, and Candida tropicalis. Antifungal susceptibility testing of 394 isolates revealed minimal levels of azole resistance among C. albicans, C. tropicalis, and C. parapsilosis. These data document the substantial burden of candidemia and its changing epidemiology. Continued surveillance will be important to monitor the epidemiology of candidemia and to detect emergence of resistance to azoles.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Persistence of Legionella pneumophila in a hospital's water system: a 13-year survey.

OBJECTIVE: To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC). DESIGN: Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE). SETTING: A large university teaching hospital. ISOLATES: All surviving isolates obtained from culture-proven nosocomial L. pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993. RESULTS: Thirty-three isolates from culture-proven nosocomial cases of L. pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period. CONCLUSION: Specific strains of L. pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.

Cross Infection↗

PubMed1999

Investigation of suspected nosocomial clusters of Staphylococcus haemolyticus infections.

OBJECTIVE: To determine whether typing methods can discriminate among Staphylococcus haemolyticus isolates. DESIGN: Molecular epidemiological evaluation of S. haemolyticus isolates obtained from patients hospitalized on a hematology service and in a surgical intensive-care unit (SICU). SETTING: A large Midwestern teaching hospital. INTERVENTIONS: None. RESULTS: Over 22 days, S. haemolyticus was isolated from five patients on the hematology service. Isolates from four patients had the same unusual antibiogram and biotype. Ribotyping, restriction endonuclease digestion of plasmid DNA (REAP), and whole chromosomal DNA analysis by pulsed-field gel electrophoresis (PFGE) confirmed that these isolates were identical and different from the fifth patient's isolate and from 6 control isolates. In a second cluster, 11 S. haemolyticus isolates obtained from eight patients in the SICU had similar antibiograms and biotypes. By REAP and ribotype analysis, isolates from four patients were identical. However, PFGE indicated that only two of these patients shared a common strain. CONCLUSIONS: Antibiograms or biotyping may discriminate among isolates of S. haemolyticus if the results of these tests are unusual. Many clinical isolates can be differentiated by REAP analysis, ribotyping, or PFGE. However, some isolates are identical by all of these methods, suggesting that they may have been transmitted nosocomially.

Cross Infection↗

PubMed1999

Molecular epidemiology of gram-negative bacteremia.

We did pulsed field gel electrophoresis (PFGE) and antibiotic susceptibility testing on 202 gram-negative isolates obtained from blood cultures between 1 January 1989 and 31 December 1993. Seventy-eight patients had at least two gram-negative isolates of the same species recovered from blood drawn one or more days apart and met the other study criteria. Twenty patients had only 1 bloodstream infection, 48 patients had 1 recurrence of bacteremia, and 10 patients had > 1 recurrence of bacteremia. Of 80 recurrences of bacteremia, 52 (65%) were relapses and 28 (35%) were reinfections. Seventy-eight percent of the episodes of bacteremia occurring < or = 300 days apart were relapses, and 100% occurring > 300 days apart were reinfections (P < .001). Organisms causing recurrent bacteremia were not more resistant than those causing initial episodes. In conclusion, most episodes of recurrent gram-negative bacteremia were relapses. Relapses and reinfections could not be distinguished only by the length of time between episodes or by antimicrobial susceptibility patterns.

Anti-Bacterial Agents↗

PubMed1999

Recurrent gram-negative bacteremia: incidence and clinical patterns.

Fifty-eight patients who had at least two episodes of gram-negative bacteremia were evaluated to define the epidemiology of recurrent bacteremia caused by these organisms. Thirty-two patients (55%) had single relapses, 16 (28%) had one reinfection, and 10 (17%) had more than one recurrence of bacteremia. Intravenous catheters were the most common probable source of bacteremia. Relapses occurred earlier after the initial episode than did reinfections (58 days vs. 292 days; P = .002). The duration of antibiotic therapy for the first episode was shorter for patients with relapses than for those with reinfections (13.9 days vs. 17.5 days; P = .046). Microorganisms causing recurrent bacteremic episodes were not unusually resistant to antimicrobial agents. Reinfections may be difficult to prevent because they are associated with the severity of the underlying illness, which may not improve. The frequency of relapses might be reduced by increasing the duration of antibiotic therapy and eliminating foci of infection.

Adolescent↗

PubMed1999

Nosocomial bloodstream infections in United States hospitals: a three-year analysis.

Nosocomial bloodstream infections are important causes of morbidity and mortality. In this study, concurrent surveillance for nosocomial bloodstream infections at 49 hospitals over a 3-year period detected >10,000 infections. Gram-positive organisms accounted for 64% of cases, gram-negative organisms accounted for 27%, and 8% were caused by fungi. The most common organisms were coagulase-negative staphylococci (32%), Staphylococcus aureus (16%), and enterococci (11%). Enterobacter, Serratia, coagulase-negative staphylococci, and Candida were more likely to cause infections in patients in critical care units. In patients with neutropenia, viridans streptococci were significantly more common. Coagulase-negative staphylococci were the most common pathogens on all clinical services except obstetrics, where Escherichia coli was most common. Methicillin resistance was detected in 29% of S. aureus isolates and 80% of coagulase-negative staphylococci. Vancomycin resistance in enterococci was species-dependent--3% of Enterococcus faecalis strains and 50% of Enterococcus faecium isolates displayed resistance. These data may allow clinicians to better target empirical therapy for hospital-acquired cases of bacteremia.

Bacteremia↗

PubMed1999

Survey of bloodstream infections due to gram-negative bacilli: frequency of occurrence and antimicrobial susceptibility of isolates collected in the United States, Canada, and Latin America for the SENTRY Antimicrobial Surveillance Program, 1997.

During 1997, a total of 4,267 nosocomial and community-acquired bloodstream infections due to gram-negative organisms were reported from SENTRY hospitals in Canada (8 sites), the United States (30 sites), and Latin America (10 sites). Escherichia coli was the most common isolate (41% of all gram-negative isolates), followed by Klebsiella species (17.9%), Pseudomonas aeruginosa (10.6%), and Enterobacter species (9.4%). For all gram-negative isolates combined, the most active antimicrobials tested were meropenem, imipenem, and cefepime. The quinolones levofloxacin (MIC90, 2 microg/mL), ciprofloxacin (MIC90, 1 microg/mL), gatifloxacin (MIC90, 2 microg/mL), sparfloxacin (MIC90, 2 microg/mL), and trovafloxacin (MIC90, 2 microg/mL) were also active against most isolates. Bloodstream infection isolates from Latin America were uniformly more resistant to all classes of antimicrobial agents tested than were isolates from Canada or the United States. Resistance phenotypes consistent with extended-spectrum beta-lactamase production were also most common among E. coli and Klebsiella species from Latin America. Further investigation of the reasons for regional differences in resistance patterns is needed, as is ongoing surveillance to detect resistance trends and to guide antimicrobial use.

Bacteremia↗

PubMed1999

In vitro activities of voriconazole, fluconazole, and itraconazole against 566 clinical isolates of Cryptococcus neoformans from the United States and Africa.

We investigated the in vitro activity of voriconazole compared to those of fluconazole and itraconazole against 566 clinical isolates of Cryptococcus neoformans from Africa (164) and the United States (402). Isolates were obtained from cerebrospinal fluid (362), blood (139), and miscellaneous sites (65). Voriconazole (MIC at which 90% of the isolates are inhibited [MIC90], 0.12 to 0.25 microg/ml) was more active than either itraconazole (MIC90, 0.5 microg/ml) or fluconazole (MIC90, 8.0 to 16 microg/ml) against both African and U. S. isolates. Isolates inhibited by >/=16 microg of fluconazole per ml were almost all (99%) inhibited by </=1 microg of voriconazole per ml. These results suggest that voriconazole may be useful in the treatment of cryptococcosis.

Africa↗

PubMed1999

Haemophilus influenzae and Moraxella catarrhalis from patients with community-acquired respiratory tract infections: antimicrobial susceptibility patterns from the SENTRY antimicrobial Surveillance Program (United States and Canada, 1997).

Between February and June of 1997, a large number of community-acquired respiratory tract isolates of Haemophilus influenzae (n = 1,077) and Moraxella catarrhalis (n = 503) from 27 U.S. and 7 Canadian medical centers were characterized as part of the SENTRY Antimicrobial Surveillance Program. Overall prevalences of beta-lactamase production were 33.5% in H. influenzae and 92.2% in M. catarrhalis with no differences noted between isolates recovered in the United States and those from Canada. Among a total of 21 different antimicrobial agents tested, including six cephalosporins, a beta-lactamase inhibitor combination, three macrolides, tetracycline, trimethoprim-sulfamethoxazole (TMP-SMX), rifampin, chloramphenicol, five fluoroquinolones, and quinupristin-dalfopristin, resistance rates of > 5% with H. influenzae were observed only with cefaclor (12.8%) and TMP-SMX (16.2%).

Anti-Bacterial Agents↗

PubMed1999

In vitro activities of BMS-207147 against over 600 contemporary clinical bloodstream isolates of Candida species from the SENTRY Antimicrobial Surveillance Program in North America and Latin America.

We compared the in vitro activity of BMS-207147, an investigational triazole, with those of itraconazole and fluconazole against 613 clinical bloodstream isolates of Candida spp. collected from SENTRY participating hospitals during 1997 and 1998. Overall, BMS-207147 was the most active azole against all Candida spp. While both BMS-207147 and itraconazole displayed a stepwise decrease in activity against isolates for which the fluconazole MICs were elevated, BMS-207147 had two- to fourfold greater activity than itraconazole both against Candida spp. that were dose-dependently fluconazole susceptible and against those that were fluconazole resistant.

Antifungal Agents↗

PubMed1999

Identification of Candida dubliniensis based on temperature and utilization of xylose and alpha-methyl-D-glucoside as determined with the API 20C AUX and vitek YBC systems.

To have a better understanding of the role of Candida dubliniensis in clinical infections, it is essential that microbiology laboratories can identify this species rapidly and accurately in clinical specimens. C. dubliniensis has been reported to lack the ability to utilize xylose (XYL) and alpha-methyl-D-glucoside (MDG) and to grow poorly or not at all at 45 degrees C, whereas Candida albicans isolates utilize XYL and MDG and usually grow well at 45 degrees C. We tested 66 isolates of C. dubliniensis and 100 isolates of C. albicans with both the API 20C AUX and Vitek YBC systems to evaluate the ability of the XYL and MDG tests contained within each of these systems to distinguish between the two species. The ability to grow at 45 degrees C was also examined. None of the C. dubliniensis isolates grew at 45 degrees C, and 23 of 100 C. albicans isolates (23%) exhibited poor or no growth at 45 degrees C. The XYL and MDG tests contained within the API 20C AUX system were both negative for all 66 C. dubliniensis isolates and were positive for 98 (XYL) and 56 (MDG) of the 100 C. albicans isolates. With the Vitek system, 64 of 66 C. dubliniensis isolates (97.0%) were XYL negative and 63 (95.0%) were MDG negative. Conversely, 96 of 100 C. albicans isolates (96.0%) were XYL positive and 100 (100.0%) were MDG positive with the Vitek system. Clinical microbiology laboratories could use lack of growth at 45 degrees C and a negative XYL test with either the API 20C AUX or Vitek yeast identification system to provide a presumptive identification of C. dubliniensis. A negative MDG test result with either system would also be helpful but may misclassify C. albicans as C. dubliniensis, especially when the API 20C AUX system is used.

Candida↗