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S Messer

Publications and source records attributed to S Messer.

16 recordsLinked to original sources
PubMed2002

Antifungal susceptibility of South African oral yeast isolates from HIV/AIDS patients and healthy individuals.

The in vitro antifungal susceptibility profile of 589 oral yeast isolates from HIV/AIDS patients and healthy South Africans was determined against amphotericin B, nystatin, 5-fluorocytosine (5-FC), clotrimazole, miconazole, ketoconazole, itraconazole and fluconazole. The broth microdilution method of the National Committee on Clinical Laboratory Standards was used and MIC(50) and MIC(90) determined. A 100% susceptibility to fluconazole was observed among the 466 isolates of Candida albicans. Among C. krusei, the second most common isolate, only 2.6% of isolates were susceptible to fluconazole and itraconazole. Despite the lack of previous exposure to antifungal agents, very little difference was observed in the antifungal profile between the South African isolates and isolates from the United States (U.S.), Canada and South America. South Africa has a particularly high incidence of HIV-infection and oral candidiasis is the most common oral complication in these patients. This study provides important baseline data as the isolates were collected prior to fluconazole being made freely available to HIV/AIDS patients attending government health clinics.

AIDS-Related Opportunistic Infections↗
PubMed2002

An evaluation of the performance of XLD, DCA, MLCB, and ABC agars as direct plating media for the isolation of Salmonella enterica from faeces.

AIMS: To compare the performance of four media, singly and in combination, as direct plating media for the isolation of Salmonella enterica from human faeces. METHODS: Two thousand four hundred and nine routine, faecal samples received by four laboratories were inoculated on to xylose lysine desoxycholate (XLD), desoxycholate citrate (DCA), mannitol lysine crystal violet brilliant green (MLCB), and alpha-beta chromogenic (ABC) agars using standardised protocols, reagents, and data collection. Isolates of presumptive salmonellae were identified using standard laboratory techniques and the results were analysed statistically. RESULTS: Direct plating recovered 46 of the 60 possible isolates of Salmonella spp recovered via enrichment broth. No isolates were recovered from direct plating that were not recovered via selenite enrichment. MLCB gave the highest isolation rate individually (84.8%) and amounts of competing flora (CF) did not affect the recognition of colonies. ABC proved highly specific, but insensitive, and isolation rates were adversely affected by any amount of CF. Isolation rates from XLD and DCA were only affected when the CF load was heavy. DCA was least specific, with only 9.01% of picks positive and greatest number of confirmatory tests. XLD and MLCB, in combination, gave the highest isolation rate. CONCLUSIONS: Where the earlier results of direct plating may be advantageous, XLD and MLCB provide the optimal combination. For non-typhi salmonellae, MLCB is the best, single direct plating medium. For routine diagnostic work, XLD is most effective.

Bacteriological Techniques↗
PubMed2002

Effect of incubation temperature on the isolation of thermophilic species of Campylobacter from faeces.

Although no large-scale clinical study has been performed, it has been reported that incubation at 37 degrees C gives better isolation rates for all common species of Campylobacter than incubation at 42 degrees C, while also improving the recovery of the more unusual species. In this study, 2,570 faecal samples were examined in four laboratories, using a standardised protocol. Isolation rates of Campylobacter spp. were compared after incubation on modified campylobacter blood-free selective agar at 37 degrees C and 42 degrees C. Campylobacter spp. isolates were made from 185 samples (7.2%); 25 were recovered only at 42 degrees C and three only at 37 degrees C (p < 0.001). There were significantly more colonies at 42 degrees C (p = 0.001). Competing flora were heavier at 37 degrees C, but this did not account for the difference in isolation rates or quantity of growth. It is recommended that cultures for Campylobacter spp. be routinely incubated at 42 degrees C. More specific techniques are required to seek for fastidious campylobacters.

Agar↗
PubMed2001

A comparison of the performance of bacitracin-incorporated chocolate blood agar with chocolate blood agar plus a bacitracin disk in the isolation of Haemophilus influenzae from sputum.

The lack of selectivity of chocolated blood agar (CBA), routinely used for the isolation of Haemophilus influenzae, may lead to masking of the growth of H. influenzae due to overgrowth of competing flora. Bacitracin can be used as a selective agent, either incorporated into the medium or applied to the medium in a filter paper. However, neither method has been evaluated or compared in a large study. Sputum samples (1990) were examined in four laboratories and the isolation rates of H. influenzae on chocolated blood agar with bacitracin added to the medium (BCA) and chocolated blood agar (CBA) with a bacitracin disk were compared. A plain blood agar plate was also inoculated to facilitate the isolation of Streptococcus pneumoniae so that its effects on the isolation of H. influenzae could be assessed. No significant difference was found between the isolation rates of H. influenzae on BCA and CBA with a bacitracin disk, although competing flora was greatly reduced and quantity of growth of H. influenzae increased on BCA. The presence of S. pneumoniae did not affect the isolation of H. influenzae in this study.

Anti-Bacterial Agents↗
PubMed2001

A comparison of the isolation rates of Salmonella and thermophilic Campylobacter species after direct inoculation of media with a dilute faecal suspension and undiluted faecal material.

Regardless of media used, dilution of faecal samples before direct plating may improve isolation rates and reduce subcultures by freeing organisms from the faecal mass and diminishing competing flora. Despite the routine use of dilution in many laboratories, it has never been established properly whether direct or dilute inocula should be used in primary plating of faeces. A total of 3764 faecal samples was examined in four laboratories with a standardised methodology. The isolation rates, competing flora and confirmatory work performed for Salmonella spp. and Campylobacter spp. from primary plating media with a dilute faecal inoculum were compared with those after direct inoculation of faecal material. Inoculum effects on the isolation of Shigella spp. could not be assessed as only one isolate occurred during the study period. The overall isolation rates of both major enteric pathogens were unaffected by the inoculum. However, significantly fewer wasted subcultures were recorded with a dilute inoculum for Campylobacter spp., and competing florawas reduced in all cases without diluting out small numbers of the pathogen.

Campylobacter↗
PubMed2000

A head-on comparison of the in vitro antifungal activity of conventional and lipid-based amphotericin B: a multicenter study.

A comparative study of conventional amphotericin B, Abelcet and AmBisome was performed using a microdilution format of the NCCLS M27-A methodology for susceptibility testing against 300 fungal isolates (152 yeasts, 148 filamentous fungi) in both RPMI-1640 and antibiotic medium #3 (AB3). The clinical isolates included Candida albicans (n=54), Candida glabrata (n=25), Candida parapsilosis (n=23), Candida krusei (n=19), Candida lusitaniae (n=14), Cryptococcus neoformans (n=5), Candida tropicalis (n=12), Aspergillus flavus (n=34), Aspergillus fumigatus (n=46) and 68 other filamentous fungi encompassing 22 different genera. The minimal inhibitory concentrations (MIC) for all drugs were defined as the lowest concentrations in which there was no visible growth. MICs were determined after 48 h for yeasts and 72 h for filamentous fungi. The mean MICs +/- standard error (microg/ml) for yeasts and filamentous fungi, respectively, were: Abelcet, 0.51+/-0.21, 4.34+/-0.61; AmBisome, 1.28+/-0.24, 5.68+/-0.57; amphotericin B, 0.29+/-0.11, 1.12+/-0.19, respectively. Overall, against both yeasts and filamentous fungi Abelcet proved to have more potent antifungal activity than AmBisome. Using AB3 as opposed to RPMI-1640 generally produced lower MIC values but did not have any effect on the order of relative activity with all of the antifungal agents tested. In conclusion, our data shows that Abelcet is more active than AmBisome against pathogenic yeast and filamentous fungi when assayed in AB3 in vitro. Comparison of the activities of these antifungals in experimental animal models is necessary to determine whether these in vitro findings are correlated with in vivo efficacy.

Amphotericin B↗
PubMed1999

A comparison of blood agar supplemented with NAD with plain blood agar and chocolated blood agar in the isolation of Streptococcus pneumoniae and Haemophilus influenzae from sputum. Bacterial Methods Evaluation Group.

Streptococcus pneumoniae grows well and generally exhibits typical morphology on Columbia blood agar, whereas Haemophilus influenzae requires a more complex medium to meet its growth requirements - usually chocolated blood agar - on which S. pneumoniae is less easily recognisable. Therefore, a single medium that produces typical morphology of S. pneumoniae and facilitates the growth of H. influenzae would have considerable potential advantages. It has been claimed that blood agar supplemented with nicotinamide adenine dinucleotide (NAD) is such a medium. However, despite its routine use in several large diagnostic laboratories its performance has never been properly evaluated. In the present study, 1724 sputum samples were examined in four laboratories. The isolation rates of H. influenzae and S. pneumoniae on NAD-supplemented blood agar (SBA) were compared with those on a two-plate combination of plain blood (BA) and chocolated blood agar (CBA). The two-plate combination performed significantly better for both organisms; isolation rates for H. influenzae were increased from 8.16% on SBA to 11.07% on BA plus CBA and for S. pneumoniae from 4.18% to 4.68%. Isolation rates were also compared after incubation for 24 and 48 h. With the two-plate combination, isolation rates for H. influenzae and S. pneumoniae were increased by 0.98% and 0.16%, respectively, and for SBA by 0.57% and 0.32% after 48 h. However, despite this increase, SBA still performed less well than the two-plate combination.

Agar↗
PubMed1998

Molecular epidemiology and antifungal susceptibility of Cryptococcus neoformans isolates from Ugandan AIDS patients.

Little is known of the antifungal susceptibility patterns and molecular epidemiology of Cryptococcus neoformans from tropical regions. We studied 164 clinical isolates of C. neofomans from 120 Ugandan AIDS patients with cryptococcal meningitis by analyzing their electrophoretic karyotypes and antifungal susceptibility profiles. Computer-assisted analysis of karyotype patterns was performed to generate dendrograms. MICs of fluconazole and flucytosine were determined by reference methods. A total of 43 distinguishable DNA types were identified among the 164 isolates. Only 30 patients (25%) were infected with their own unique strain of c. neoformans, whereas 75% of the patients shared their infecting strain with at least one other patient. Among 17 patients with more than one CSF isolate of C. neoformans, sequential isolates were identical or highly related in 12 (71%) and were different in five patients (29%). The isolates were susceptible to both fluconazole and flucytosine and there were no instances in which a stepwise increase in either fluconazole or flucytosine MICs was observed among serial isolates. These findings suggest that the epidemiology of cryptococcal disease in AIDS patients from tropical regions may be somewhat different from that observed in more temperate climates.

Acquired Immunodeficiency Syndrome↗
PubMed1998

In vitro activities of voriconazole (UK-109,496) and four other antifungal agents against 394 clinical isolates of Candida spp.

Voriconazole (formerly UK-109,496) is a new monotriazole antifungal agent which has potent activity against Candida, Cryptococcus, and Aspergillus species. We investigated the in vitro activity of voriconazole compared to those of fluconazole, itraconazole, amphotericin B, and flucytosine (5FC) against 394 bloodstream isolates of Candida (five species) obtained from more than 30 different medical centers. MICs of all antifungal drugs were determined by the method recommended by the National Committee for Clinical Laboratory Standards using RPMI 1640 test medium. Overall, voriconazole was quite active against all the yeast isolates (MIC at which 90% of the isolates are inhibited [MIC90], < or =0.5 microg/ml). Candida albicans was the most susceptible species (MIC90, 0.06 microg/ml) and Candida glabrata and Candida krusei were the least (MIC90, 1 microg/ml). Voriconazole was more active than amphotericin B and 5FC against all species except C. glabrata and was also more active than itraconazole and fluconazole. For isolates of Candida spp. with decreased susceptibility to fluconazole and itraconazole MICs of voriconazole were also higher. Based on these results, voriconazole has promising antifungal activity and further in vitro and in vivo investigations are warranted.

Amphotericin B↗
PubMed1997

Activity of a new triazole, Sch 56592, compared with those of four other antifungal agents tested against clinical isolates of Candida spp. and Saccharomyces cerevisiae.

Sch 56592 is a new triazole agent with potent, broad-spectrum antifungal activity. The in vitro activities of Sch 56592, itraconazole, fluconazole, amphotericin B, and flucytosine (5-FC) against 404 clinical isolates of Candida spp. (382 isolates) and Saccharomyces cerevisiae (22 isolates) were investigated. In vitro susceptibility testing was performed by a broth microdilution method performed according to National Committee for Clinical Laboratory Standards guidelines. Overall, Sch 56592 was very active (MIC at which 90% of isolates are inhibited [MIC90], 0.5 microgram/ml) against these yeast isolates. Sch 56592 was most active against Candida tropicalis, Candida parapsilosis, candida lusitaniae, and Candida stellatoidea (MIC90, < or = 0.12 microgram/ml) and was least active against Candida glabrata (MIC90, 2.0 micrograms/ml). Sch 56592 was 2- to 32-fold more active than amphotericin B and 5-FC against all species except C. glabrata. By comparison with the other triazoles, Sch 56592 was equivalent to itraconazole and greater than or equal to eightfold more active than fluconazole. On the basis of these results, Sch 56592 has promising antifungal activity, and further in vitro and in vivo investigations are warranted.

Amphotericin B↗
PubMed1995

'Fifteen percent of microbiology reports are wrong!': further experience with an internal quality assessment and audit scheme.

Infection control teams critically depend on the quality of the diagnostic microbiology laboratories with which they are associated. Internal quality assessment (IQA) by specimen resubmission measures the consistency of laboratory performance and can be adapted for medical audit, but few laboratories appear to include these techniques as part of their quality control procedures. We established an IQA scheme in our bacteriology laboratory in May 1989, and the mean discrepancy rate for the first two years was nearly 15%. During the next two years covered by this report, the scheme was extended to include audit of the consistency of medical microbiologists' comments on reports, and a standardized scoring scheme was introduced. Results from the scheme are collated and analysed thrice yearly, and laboratory techniques altered and extra staff training planned to reduce discrepancies. Four thousand four hundred and fourteen specimens (1.4% workload) were resubmitted, and 325 (7.4%) gave discrepant results. During the two years, the overall discrepancy rate fell consistently from 9.4 to 3.2%. Fifty-three discrepancies (1.2%) were in microscopy, and 243 (5.5%) were between culture results. Substantial decreases in technical discrepancies followed training initiatives in sputum bacteriology, and training in anaerobic recognition and improved illumination in the anaerobic cabinet. Problems of consistent recognition of staphylococci and of urine isolates in mixed culture, and of faecal microscopy have proved difficult to eradicate. There was a 20.3% discrepancy rate between medical comments, but only 0.4% would have been likely to result in different patient outcomes. The cost of running the scheme was 4474 pounds per annum, equating to a surcharge of 0.058 pounds to each of our routine diagnostic specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic Errors↗
PubMed1995

Food-initiated outbreak of methicillin-resistant Staphylococcus aureus analyzed by pheno- and genotyping.

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) involving 27 patients and 14 health-care workers (HCW) was studied. The outbreak started in the hematology unit of the University Hospital Rotterdam, Dijkzigt, The Netherlands, and spread to the surgical unit. Twenty-one patients (77.8%) developed clinical disease, and five died. Subsequently, MRSA was detected in food and in the throat of one of the HCW who prepared food for hematology patients. Food contaminated by an HCW most likely caused the first case of MRSA septicemia. This route of transmission has not been described before. The outbreak strain was probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne MRSA transmission played an important role in disseminating the organism. The outbreak was controlled within 6 months by intensifying surveillance, temporarily closing the affected wards, treating carriers, and instituting an MRSA ward outside the hospital. Phage typing, insertion sequence probing, protein A gene typing, and DNA fingerprinting by PCR revealed that all outbreak-related isolates were identical. By pulsed-field gel electrophoresis, all but one of the outbreak-related isolates were determined to be identical. Protein A gene typing identified numerous (11) repeat units in all outbreak-related isolates, which supports the suggestion that the outbreak strain may have been more virulent and more transmissible than other MRSA strains. Pheno- and genotyping studies underlined the value of DNA fingerprinting methods for investigation of MRSA epidemiology. Optimal discriminatory power was achieved by combining the results of four genotyping methods.

Base Sequence↗
PubMed1993

Development of an internal quality assessment scheme in a clinical bacteriology laboratory.

AIM: To develop an internal quality assessment (IQA) scheme in a clinical bacteriology laboratory. METHODS: Over 24 months, 1230 diagnostic specimens, representing 0.42% of laboratory workload, were anonymised and resubmitted for analysis. Six hundred and twenty one (48.7%) of these gave positive culture results; 44 fecal and upper respiratory specimens were "spiked" (artificially inoculated) to increase the proportion of positive samples. RESULTS: Discrepancies between IQA and clinical sample results occurred in 188 cases (14.8%): 76.6% of these were in culture results, 13.3% in microscopy performance, and 10.1% in clerical recording. The culture discrepancy rate for each positive sample was lowest for wound (17.5%) and urine (18.1%) specimens, and highest for faeces (34.9%) and upper respiratory (37.7%) samples. Discrepancies in several areas responded to staff training and improvement in technical methods. CONCLUSIONS: An IQA programme of this type assesses the reproducibility of tests within a diagnostic laboratory when analysing common specimen types and organisms. It permits blind assessment of many areas of diagnostic work that are not readily amenable to other quality assurance methods, and it raises the awareness of all staff to the importance of quality in every aspect of specimen and data processing.

Bacteriological Techniques↗