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Biomedical subjects

M A Pfaller

Publications and source records attributed to M A Pfaller.

At least 379 records · Page 21Linked to original sources
PubMed1992

Spontaneously occurring staphylococcal mutants resistant to clinically achievable concentrations of ciprofloxacin and temafloxacin.

The frequency of spontaneously occurring mutants resistant to 0.5, 1, 2, 4 and 8 micrograms of temafloxacin or ciprofloxacin per milliliter was documented with four Staphylococcus aureus and four Staphylococcus epidermidis strains. Resistant mutants were recovered at two- to four-fold the MIC of either drug, and they displayed cross-resistance to other fluoroquinolones. Resistance to temafloxacin occurred at frequencies lower than those observed with equal concentrations of ciprofloxacin. Resistance to greater than four-fold the MIC of either drug was not detected (frequencies less than 10(-10).

Anti-Infective Agents↗
PubMed1992

Colonization with coagulase-negative staphylococci in two neonatal units.

Episodes of septicaemia due to coagulase-negative staphylococci (CNS) were more frequent in a level III than in a level II neonatal unit in Stockholm, Sweden. Colonization with CNS during the first 2 weeks of life was investigated in 10 infants from each unit. As the use of antibiotics differed between the two units, the aim was to correlate colonization and antimicrobial resistance patterns to antibiotic usage. Antimicrobial susceptibility of CNS to isoxazolylpenicillins, co-trimoxazole, erythromycin, clindamycin, chloramphenicol and gentamicin was determined. Selected isolates were typed with restriction endonuclease analysis of plasmid DNA and of genomic DNA. Infants were frequently colonized with multiple strains and species of CNS, and transmission of strains from patient to patient occurred within the unit. Qualitative and quantitative differences in antibiotic use were not correlated with colonization. The prevalence of resistant isolates, mostly of Staphylococcus haemolyticus, was higher in the level II unit with lower use of antibiotics. Staphylococcus epidermidis, which is generally more virulent, prevailed in the level III unit, where there were more severely ill children and invasive procedures were more frequently performed.

Anti-Bacterial Agents↗
PubMed1992

Interpretive criteria and quality control guidelines for lomefloxacin and meropenem in susceptibility tests of Haemophilus influenzae using Haemophilus test medium.

Lomefloxacin and meropenem were tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Haemophilus influenzae using Haemophilus test medium (HTM). Interpretive criteria were established by using triplicate testing of 102 representative H. influenzae strains. Only a susceptible category was proposed for lomefloxacin (greater than or equal to 22 mm and less than or equal to 2 micrograms/ml) and meropenem (greater than or equal to 13 mm and less than or equal to 4 micrograms/ml) due to the lack of resistant isolates. QC range for H. Influenzae ATCC 49247 were established using multiple HTM agar and broth base lots, three disk lots for each drug, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards M23-T guideline.

Anti-Infective Agents↗
PubMed1992

Cefdinir (FK482), an orally administered cephalosporin in vitro activity comparison against recent clinical isolates from five medical centers and determination of MIC quality control guidelines.

Cefdinir, a new oral cephalosporin, was compared to cefaclor, cefadroxil, cefixime, and cefuroxime against greater than 5000 recent aerobic clinical isolates. This multicenter study revealed broad-spectrum cefdinir activity against all Enterobacteriaceae (MIC50s, 0.06-2 micrograms/ml) except Enterobacter cloacae, Morganella morganii, Proteus vulgaris, and Serratia marcescens (MIC50s, greater than or equal to 4 micrograms/ml). Oxacillin-susceptible staphylococci (MIC90s, 0.5-2 micrograms/ml), beta-hemolytic Streptococcus group B (MIC90, 0.06 micrograms/ml), and Acinetobacter lwoffii were also susceptible to cefdinir. The activity of cefdinir was similar to that of cefixime and cefuroxime against Gram-negative organisms and superior to all tested oral cephems when tested against Gram-positive cocci. None of the cephalosporins were active against oxacillin-resistant Staphylococcus spp., enterococci, Pseudomonas spp., or Xanthomonas maltophilia. MIC quality control range guidelines were established for the strains recommended by the National Committee for Clinical Laboratory Standards documents.

Anti-Bacterial Agents↗
PubMed1992

Outbreak of Candida bloodstream infections associated with retrograde medication administration in a neonatal intensive care unit.

An outbreak of candidemia involving five infants receiving total parenteral nutrition in the neonatal intensive care unit was investigated. Cultures of the intravenous fluids demonstrated that the retrograde medication syringe fluids were significantly more likely to be contaminated with Candida than were other fluids being administered to the infants (p less than 0.001). Candidemia was significantly associated with total parenteral nutrition (p = 0.04) and retrograde medication administration (p = 0.02). A survey of nursing practice found that reuse of the retrograde syringes was the most likely cause of contamination. Molecular typing showed that the strains of Candida albicans that were isolated from the bloodstream were also found in the retrograde syringes and that at least three strains of C. albicans and one strain each of Candida tropicalis and Candida parapsilosis were involved. In vitro growth curves demonstrated that Candida species had a selective growth advantage versus bacteria in the total parenteral nutrition fluid. An in vitro simulation of the retrograde medication administration system suggested that the outbreak probably developed after the frequency of changing intravenous tubing was decreased from every 24 hours to every 72 hours. The outbreak was terminated by using syringes only once and resuming intravenous tubing changes every 24 hours. Retrograde medication administration in association with total parenteral nutrition may increase the risk of Candida line infection.

Candida↗
PubMed1992

Molecular epidemiology of coagulase-negative staphylococci isolated from immunocompromised patients.

OBJECTIVE: To define the source of invasive coagulase-negative staphylococci (CNS) and the epidemiology of strain variation in immunocompromised patients. DESIGN: Weekly microbial surveillance cultures were obtained from the nares, throat, skin, rectum, and urine. Plasmid pattern analysis was performed on all coagulase-negative staphylococci isolated from blood cultures and on selected strains from the surveillance sites. SETTING: A 902-bed, university-owned, tertiary-care referral hospital. PARTICIPANTS: Forty-four patients on the bone marrow transplant or hematologic malignancy services. RESULTS: Plasmid pattern analysis was performed on 340 surveillance isolates (median = 7 per patient) and 201 bloodstream isolates (median = 3 per patient). Patients were colonized with numerous unique strains (median = 5 per patient) of coagulase-negative staphylococci. The 44 patients had 108 episodes of positive blood cultures, 20 of which were preceded by colonization with the same strain. Isolation of the matching strain from surveillance cultures preceded the positive blood culture by 1 to 8 days in 9 episodes and 18 to 389 days in 11 episodes. The matching strain was isolated from the skin in only 6 (30%) of those episodes and from mucosal sites in 70%. Of the 108 episodes of positive blood cultures, 21 were identified as nosocomial bloodstream infections. Four of the 21 nosocomial bloodstream infections were preceded by colonization with the same strain. In all 4 episodes, the infecting strain was cultured from the nares before the blood cultures were obtained. CONCLUSIONS: Our results suggest that mucous membranes might be sources for strains of CNS causing bacteremia.

Coagulase↗
PubMed1992

Epidemiological typing methods for mycoses.

Despite the increasing importance of nosocomial fungal infections, very little is known of the epidemiology, mode of transmission, or pathogenesis of infections due to fungal pathogens. Recently, a number of potentially useful epidemiological typing systems have been employed for identification of strains within species of Candida and other fungi. Epidemiological studies employing either DNA-based or protein-based typing methods have provided some interesting insights into the epidemiology of nosocomial fungal infections, particularly nosocomial candidiasis. Careful epidemiological studies employing selected typing methods are essential to the rational development of effective measures for prevention and control of nosocomial infections caused by opportunistic fungal pathogens.

Candida↗
PubMed1992

Value of the Candida antigen assay in diagnosis of systemic candidiasis in burn patients.

The Cand-tec latex agglutination test was used to analyze 2,575 serum samples from 47 consecutive burn patients at risk for systemic candidiasis and serum samples from 24 nonhospitalized control subjects. One burn patient had systemic candidiasis documented by culture of a deep biopsy specimen. In addition, blood culture produced positive results in one patient with no other evidence of systemic candidiasis. Wound, sputum, mucous membrane, or gastrointestinal tract specimens were cultured in 25 of 47 (53%) patients with no evidence of systemic candidiasis. Surveillance cultures were negative in 19 (40%) patients and there were no signs of systemic candidial infection. The sensitivity of the Candida antigen titer was 100% at titers of greater than or equal to 1:2, greater than or equal to 1:4, greater than or equal to 1:8, and greater than or equal to 1:16. Specificity was 77% at titers of greater than or equal to 1:4, 94% at titers of greater than or equal to 1:8, and 100% at titers of greater than or equal to 1:16. The positive predictive value ranged from 6.0% at greater than or equal to 1:4 to 100% at greater than or equal to 1:16. The negative predictive value was 100% for all titer values. The Cand-tec antigen test shows poor specificity and poor positive predictive value for the detection of systemic candidiasis in burn patients.

Adolescent↗
PubMed1992

Ticarcillin and ticarcillin-clavulanic acid susceptibility tests: error rates for disk tests with consecutively isolated members of the family Enterobacteriaceae.

A five-laboratory coordinated study was undertaken to determine whether ticarcillin and ticarcillin-clavulanic acid disk susceptibility tests could accurately detect resistance among enteric bacilli. Each facility performed disk tests and broth microdilution susceptibility tests with reagents distributed from a common source, and appropriate controls were included in order to ensure methodologic uniformity. Each institution tested 500 consecutively isolated enteric bacilli against ticarcillin and ticarcillin-clavulanic acid. The prevalence of discrepancies between disk tests and dilution tests with 2,435 unselected enteric bacilli provided a valid estimate of the true error rate for tests with the two disks. The current interpretive criteria for susceptibility tests with ticarcillin and ticarcillin-clavulanic acid disks were found to be reliable; i.e., there were major or very major discrepancies between MIC categories and disk test results for less than 1% of all strains and minor discrepancies for only 5 to 10%. Even lower error rates would occur if the zone size-interpretive criteria were modified, but at this time it is difficult to determine whether the practical problems created by making such changes can be justified by the magnitude of the problem that is being resolved.

Clavulanic Acids↗
PubMed1992

Standardized susceptibility testing of fluconazole: an international collaborative study.

An international collaborative study of broth dilution (MIC) and disk diffusion susceptibility testing of fluconazole was conducted by using a chemically defined medium (High-Resolution Antifungal Assay Medium; Oxoid Ltd., Basingstoke, United Kingdom) and standard test methods performed in eight reference laboratories. Ten yeast isolates were tested by each test method in duplicate on each of 3 separate days. The intralaboratory reproducibility of the MIC test was excellent; 95.7% of the replicate tests (n = 220) were within 2 doubling dilutions of the other values in the set for the eight laboratories. The intralaboratory reproducibility of the disk test was also good, with 91% of the replicate tests (n = 234) agreeing with each other within an arbitrarily chosen value of 4 mm. Interlaboratory agreement of MIC test results was acceptable, with 84% of the MICs agreeing within 2 doubling dilutions. In contrast, the interlaboratory agreement of the disk test was not good, with only 59% of test results agreeing within 4 mm. Comparison of the rank order of MICs obtained in each laboratory with the reference rank order gave an agreement of 70 to 80% (median, 80%) with the MIC test and 70 to 90% (median, 80%) with the disk test. These preliminary results are encouraging for the development of standardized testing methods for testing fluconazole.

Culture Media↗
PubMed1992

Collaborative comparison of broth macrodilution and microdilution antifungal susceptibility tests.

A collaborative comparison of macro- and microdilution antifungal susceptibility tests was performed in five laboratories. MICs of amphotericin B, fluconazole, flucytosine, and ketoconazole were determined in all five centers against 95 coded isolates of Candida spp., Cryptococcus neoformans, and Torulopsis glabrata. A standard protocol with the following National Committee for Clinical Laboratory Standards Subcommittee on Antifungal Susceptibility Testing recommendations was used: an inoculum standardized by spectrophotometer, buffered (RPMI 1640) medium (pH 7.0), incubation at 35 degrees C, and an additive drug dilution procedure. Two inoculum sizes were tested (1 x 10(4) to 5 x 10(3) to 2.5 x 10(3) CFU/ml) and three scoring criteria were evaluated for MIC endpoint determinations, which were scored as 0 (optically clear), < or = 1 (slightly hazy turbidity), and < or = 2 (prominent decrease in turbidity compared with that of the growth control). Overall intra- and interlaboratory reproducibility was optimal with the low-density inoculum, the second-day readings, and MICs scored as either 1 or 2. The microdilution MICs demonstrated interlaboratory agreement with most of the four drugs higher than or similar to that of the macrodilution MICs. In general, there was good interlaboratory agreement with amphotericin B, fluconazole, and flucytosine; ketoconazole gave more variable results.

Antifungal Agents↗
PubMed1991

Infection control: the premier quality assessment program in United States hospitals.

The three decennial international meetings of the Centers for Disease Control have reaffirmed the national health priority for prevention of nosocomial infections. Moreover, the past 20 years have seen the institutionalization of the infection control practitioner and hospital epidemiologist. The epidemiologic activities of these two groups have included access to medical care, identification of risk factors, and both prevention and control of adverse nosocomial events. As such, they represent experience with issues commonly referred to as quality of care. It is argued that infection control not only is now but has been from its inception the premier quality assessment program in the United States. Moreover, it is the only activity in quality assessment that has been shown to be efficacious.

Cross Infection↗
PubMed1991

Methicillin-resistant Staphylococcus aureus: implications for the 1990s and effective control measures.

Data from around the world verify the escalating incidence of infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Since MRSA are spread primarily on the hands of health care workers, rates of infection are a function of infection control activities within institutions. Moreover, infections with MRSA are serious and often life-threatening. Thus, there are compelling medical and ethical reasons to invest in control measures. Currently available data suggest the efficacy of three measures: (a) identification of the entire patient reservoir (cases and carriers) for purposes of isolation; (b) strict handwashing between patients to prevent transmission; and (c) treatment of the carrier state in health care workers and patients during periods of high infection rates with safe and effective topical agents such as mupirocin.

Carrier State↗
PubMed1991

Reemergence of epidemic methicillin-resistant Staphylococcus aureus in a general hospital associated with changing staphylococcal strains.

An epidemic of methicillin-resistant Staphylococcus aureus (MRSA) infections involving 323 patients occurred at the University of Cincinnati Hospital from 1977 to 1981. Subsequently, endemic MRSA persisted in the hospital for 6 years, until 1987, when a new epidemic began with 223 patients becoming infected over 3 years. Between the two epidemics, there was a major change in the MRSA recovered from infected patients, as demonstrated by three epidemiologic markers. Antibiograms showed that the tetracycline-resistant MRSA involved in the first epidemic was replaced by tetracycline-susceptible MRSA in the second epidemic; bacteriophage typing indicated that the original epidemic strain, D11/83A/85, had been replaced by new strains, many of which were susceptible to phage 54; and restriction endonuclease analysis of plasmid DNA confirmed that a single strain was involved in the first epidemic and that multiple strains were present in the second epidemic. The epidemiology of MRSA infections in the hospital changed with the change in staphylococcal strains. The first epidemic was hospital based with most infections occurring in surgical patients, and the burn unit was the major reservoir. In contrast, 28% of the patients in the second epidemic had community-acquired infections, and nursing home patients were an important source of these infections. Also, 29% of the hospital-acquired infections in this epidemic occurred in nonsurgical patients. This time the burn unit was not a reservoir of infection, but other intensive care units were. The increased diversity of strains of MRSA in the second epidemic might be related to increased transmission in the community and more widespread transmission in the hospital.

Bacteriophage Typing↗
PubMed1991

Reduced intravascular catheter infection by antibiotic bonding. A prospective, randomized, controlled trial.

We report a prospective, randomized, controlled clinical trial to evaluate the efficacy of antibiotic-bonded catheters in reducing the incidence of intravascular catheter-related infections. Ninety-three central venous catheters and 85 arterial catheters were studied in the surgical intensive care unit. Study catheters were pretreated with the cationic surfactant tridodecylmethylammonium chloride. The anionic antibiotic, cefazolin, was bonded before insertion of the catheters by immersing them in a 50-mg/mL solution. Fourteen percent of the 81 catheters in the control group were infected, compared with 2% of the 97 antibiotic-bonded catheters. Staphylococcus epidermidis was the most common organism obtained. There was no significant difference in the number of colonized or clinically inflamed catheter insertion sites. None of the 100 antibiotic immersion solutions yielded anything on microbiologic culture. We conclude that antibiotic bonding is an efficient, safe, and cost-effective method of reducing intravascular catheter infection in patients who are in intensive care units.

Bacterial Infections↗