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Biomedical subjects

M H Roe

Publications and source records attributed to M H Roe.

At least 19 recordsLinked to original sources
PubMed1999

Comparison of isolation media for recovery of Burkholderia cepacia complex from respiratory secretions of patients with cystic fibrosis.

Burkholderia cepacia selective agar (BCSA) has previously been devised for isolation of B. cepacia from respiratory secretions of patients with cystic fibrosis and tested under research laboratory conditions. Here we describe a study in which BCSA, oxidation-fermentation polymyxin bacitracin lactose agar (OFPBL), and Pseudomonas cepacia agar (PCA) were compared in routine culture procedures for the ability to grow B. cepacia and inhibit other organisms. Three hundred twenty-eight specimens from 209 patients at two pediatric centers and 328 specimens from 109 adults were tested. Plates were inoculated, incubated, and read for quality and quantity of growth at 24, 48, and 72 h. Five (1.5%) specimens from 4 (1.9%) children and 75 (22.9%) specimens from 16 (14.7%) adults grew B. cepacia complex. At 24, 48, and 72 h, BCSA achieved 43, 93, and 100% detection, respectively; OFPBL achieved 26, 84, and 96%, respectively; and PCA achieved 33, 74, and 84% detection, respectively. Quality was assessed as pinpoint or good growth. At 24 h, most cultures growing B. cepacia complex had pinpoint colonies. By 48 and 72 h, 48 and 69% of B. cepacia complex cultures, respectively, had good growth on BCSA, while on OFPBL 19 and 30%, respectively, had good growth and on PCA 11 and 18%, respectively, had good growth. BCSA was superior to OFPBL and PCA in suppressing organisms other than B. cepacia complex; 40 non-B. cepacia complex organisms were isolated from BCSA, 263 were isolated from OFPBL, and 116 were isolated from PCA. We conclude that BCSA is superior to OFPBL and PCA in its ability to support the growth of B. cepacia complex and to suppress other respiratory organisms.

Adult↗
PubMed1993

Innovative index system for reporting microbiology laboratory results.

A new computerized format for presenting microbiology laboratory results has been designed and evaluated. This new system uses an index format providing a concise summary of the status of each test ordered and the results for each test organized by the source of the specimen on the first page of the report. This is followed by complete, detailed microbiology results sorted in reverse chronological order. This new system was significantly (P < 0.05) faster and easier to use than a standard source-category reporting system used in many hospitals. In addition, the index format was overwhelmingly preferred by the individuals evaluating both systems.

Abstracting and Indexing↗
PubMed1987

Comparison of three latex agglutination kits and counterimmunoelectrophoresis for the detection of bacterial antigens in a pediatric population.

Three commercial latex agglutination kits (Bactigen, Wampole Laboratories, Cranbury, NJ; Directigen, Hynson, Westcott & Dunning, Baltimore, MD; Wellcogen, Wellcome Diagnostics, Dartford, England) used for the detection of bacterial polysaccharide antigens (Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis) were compared with counterimmunoelectrophoresis and Gram stain for the identification of systemic bacterial disease in children. Urine and (when available) cerebrospinal fluid specimens were saved for all patients. Positive blood or cerebrospinal fluid culture isolates included 36 with H. influenzae type b, 11 with S. pneumoniae, 3 with N. meningitidis and 6 with other organisms. All latex kits performed similarly for the detection of H. influenzae type b antigen with a sensitivity range of 91 to 100%. The four methods performed poorly for the detection of S. pneumoniae (23 to 50%) and N. meningitidis (0%) antigen. Gram stain of cerebrospinal fluid appeared to be equally sensitive to the antigen detection methods for patients with meningitis. The false positive rates for the latex kits and counterimmunoelectrophoresis ranged from 2.8 to 9.2%, with Wellcogen having the lowest rates. The false negative rates ranged from 6.5% to 12% with Directigen having the lowest rate.

Child↗
PubMed1987

Neonatal enterococcal sepsis: case-control study and description of an outbreak.

An increased incidence of neonatal sepsis caused by Group D streptococci, specifically enterococci (GDE), during a recent 6-month period prompted a 5-year review of enterococcal sepsis in our neonatal intensive care unit. Sixteen episodes occurred in 14 babies. GDE accounted for 8 of 19 (42%) episodes of neonatal bacteremia during the epidemic period vs. only 8 of 159 (5%) episodes during the remaining 4.5 years (endemic period) (P less than 0.001). Blood isolates were all identified as Streptococcus faecalis. A combination of three strain-typing methods successfully distinguished the epidemic organisms from endemic nursery strains of GDE and from "background" GDE flora in the hospital. Nursery isolates were all susceptible to ampicillin, intermediate or resistant to the aminoglycosides and variably resistant to the newer cephalosporins. There were no differences in antibiotic susceptibilities of the GDE or in characteristics of the patients that were unique to the epidemic. Neonates with GDE sepsis had a mean birth weight of 913 g, a mean gestational age of 27 weeks and a mean age of onset of sepsis of 8.5 weeks. Twenty-five controls, matched for birth weight and admission date, were identified. Significant differences (P less than 0.05) between cases and controls included: use of a nonumbilical central line (71 vs. 32%); days central line in place (26.5 vs. 6.5 days); and bowel resection (29 vs. 4%). This is the first reported outbreak of S. faecalis sepsis in neonates. GDE are important nosocomial pathogens that must be considered in late onset neonatal sepsis.

Cross Infection↗
PubMed1987

Detection of group A Streptococcus: comparison of solid and liquid culture media with and without selective antibiotics.

Eight hundred thirty-seven consecutive throat cultures from pediatric patients were cultured comparatively on conventional sheep blood agar and selective agar containing 1.25 micrograms/ml trimethoprim and 23.75 micrograms/ml sulfamethoxazole. In two sequential studies the sheep blood agar-sulfamethoxazole-trimethoprim plates were significantly (P less than 0.01) more sensitive for Group A Streptococcus (Strep-A) detection than conventional sheep blood agar plates or Todd-Hewitt broth using the fluorescent antibody-antigen detection technique. The selective plates inhibited normal upper respiratory flora but not Strep-A. An incubation time of 18 hours was significantly better than one of 4 hours for the detection of Strep-A antigen in cultures incubated in Todd-Hewitt broth alone or Todd-Hewitt-sulfamethoxazole-trimethoprim broth, resulting in a 24% increase in positives. These studies demonstrate that Strep-A detection in throat swab specimens, by either culture or antigen detection, will be influenced by the use of selective antibiotics and incubation time.

Anti-Bacterial Agents↗
PubMed1986

Microtiter broth dilution method for yeast susceptibility testing with validation by clinical outcome.

There is no ideal laboratory procedure or culture medium in current use for susceptibility testing of pathogenic yeasts. Six candidate growth media (RPMI 1640 with L-glutamine, yeast nitrogen base, Casamino Acids medium, Mueller-Hinton broth, Sabouraud dextrose broth, and minimum essential medium-Eagle salts) were screened by spectrophotometric absorbance for nucleic acid and protein. From these, two media were selected: a chemically defined growth medium (RPMI 1640 with L-glutamine) and a chemically complex medium (Casamino Acids). MICs of four antifungal agents (5-fluorocytosine, miconazole, ketoconazole, and amphotericin B) for 84 clinical isolates of various Candida species were then determined with both media in agar dilution and microtiter broth dilution systems. The resultant MICs were correlated with clinical outcome for those isolates obtained from patients treated with single antifungal agents, and susceptibility cut points were calculated. Derived MIC cut points for susceptibility were validated in a murine model of systemic candidiasis. RPMI 1640 with L-glutamine was found to have the lowest absorbance values for both nucleic acid and protein, while Casamino Acids medium was highest in both categories. We found that RPMI 1640 with L-glutamine was superior to Casamino Acids medium in the yield of MICs which correlated with actual clinical and animal outcome data. While there were no significant differences in MICs when RPMI 1640 medium was used, the microtiter broth dilution technique was superior to agar dilution in efficiency and ease of performance. We conclude that a microtiter broth system containing RPMI 1640 medium with L-glutamine is a simple, precise, and economical technique for susceptibility testing of pathogenic Candida species. We also suggest that the validation of susceptibility cut points with patient and animal outcome data make this microtiter broth system a preferential method for yeast susceptibility testing.

Amphotericin B↗
PubMed1985

Clinically significant cross-reactions with counterimmunoelectrophoresis between pneumococcus type 6 and Haemophilus influenzae type b.

Biologically and clinically significant cross-reactions may occur between the immunochemically similar capsule antigens of Haemophilus influenzae type b and Streptococcus pneumoniae type 6 by using counterimmunoelectrophoresis (CIE). In three cases of culture-proven S. pneumoniae type 6 disease, a false-positive H. influenzae type b CIE result was detected in a body fluid. Two of three cases were also positive when tested by CIE with pneumococcal omnisera. However, in one of the culture-proven cases of pneumococcal type 6 disease, the omniserum was negative and only the burro 132 H. influenzae type b antiserum demonstrated a positive precipitant reaction. In addition to the three case isolates, we evaluated nine blood or cerebrospinal fluid isolates of pneumococcus type 6, using a variety of both species- and type-specific antisera, by CIE. Two burro antisera detected 12 of 12 (100%) of the S. pneumoniae type 6 strains. A rabbit H. influenzae type b antiserum did not detect any (0 of 12; 0%) of the S. pneumoniae type 6 strains evaluated. All (12 of 12; 100%) of the S. pneumoniae type 6 strains were detected with both rabbit omniserum (S. pneumoniae) and rabbit type 6 antiserum. Our data illustrate the importance of being aware of the immunologic cross-reactivity of the H. influenzae type b capsule with the pneumococcus type 6 capsule and the possibility of false-positive results with CIE when patient specimens are interpreted.

Adolescent↗
PubMed1984

Primary plate identification of group A Streptococcus on a selective medium. Efficiency in an office practice.

The efficiency of group A Streptococcus detection and identification in an office practice was studied using a selective blood agar plate containing sulfamethoxazole and trimethoprim and primary plate bacitracin disk speciation. All results were confirmed by conventional bacteriologic and immunologic techniques the next day by a reference laboratory. In all, 1,591 cultures were processed, of which 156 (10%) could be confirmed the next morning to have group A Streptococcus by primary disk susceptibility interpretation. Bacitracin-resistant beta-hemolytic colonies, which could be immunologically confirmed as group A Streptococcus grew from only three cultures (0.1%). Fifty-six (3%) of the cultures had too few beta-hemolytic colonies to determine bacitracin susceptibility, of which 47 were later proved to be group A Streptococcus. On all preliminary negative cultures, 1% demonstrated group A Streptococcus after incubation for an additional 24 hours. If a selective blood agar plate with primary bacitracin disk susceptibility speciation is used in an office laboratory setting, 99% of all cultures can be accurately interpreted within 24 hours of incubation, providing that those plates with limited growth of beta-hemolytic colonies are thereafter immunologically tested for group A Streptococcus antigen.

Agar↗
PubMed1979

Comparison of two slide tests for detection of group A streptococcal antibodies.

Screening sera for streptococcal antibodies is a useful clinical procedure when recent streptococcal infection requires verification. Presently there are two test kits available that detect five (or more) of the antibodies that may be present. These two screening tests were compared using antistreptolysin O (ASO) and antideoxyribonuclease B (ADB) titers as the reference for true streptococcal infection. All four procedures were performed on 69 sera collected from a pediatric population. Both screening tests were found to be sensitive, specific, economical, and easy to perform; however, both were more sensitive to elevated ASO titers than to elevated ADB titers. In certain clinical situations, therefore, antibody titrations may be necessary to document completely recent streptococcal infection.

Antibodies, Bacterial↗
PubMed1977

Bacteremia in hospitalized children.

The results of 6,951 blood cultures taken from hospitalized children are reviewed. One or more organisms grew from 6% (399) of the cultures, of which 189 (two thirds) were considered to represent confirmed bacteremia. The most common organisms associated with bacteremia were Haemophilus influenzae, Streptococcus pneumoniae, enterobacteriaceae, and Staphylococcus aureus. Patients with deficient host defenses (newborns, oncology patients) with bacteremia had a higher mortality than normal children. Laboratory techniques allowing more rapid detection of positive blood cultures resulted in major alterations in therapy in almost one half of all bacteremic patients.

Anti-Bacterial Agents↗
PubMed1977

Rapid ampicillin susceptibility testing for Haemophilus influenzae.

Recent isolations of strains of Haemophilus influenzae resistant to ampicillin necessitate the development of a rapid, dependable, reproducible method of determining their antibiotic susceptibility. An agar-dilution method permitting susceptibility determinations on clinical specimens within 6-18 hours of specimen collection was designed. Chocolate agar biplates were made with one side having no additive and the other containing 2 mug/ml ampicillin. Seventy clinical specimens (cerebrospinal fluid, joint fluid, ear fluid, pleural fluid, blood culture broth) were streaked directly onto both sides of the plates when received in the laboratory and incubated at 35-37 C in 10% CO2. Reliable, readable results were usually available within 6-18 hours of receipt of the specimen and correlated completely with minimum inhibitory concentrations (MIC) determined by the agar-dilution plate method, although standard disk susceptibilities occasionally indicated false resistance. Susceptible strains (MIC less than 2 mug/ml) grew on the antibiotic-free side of the biplate only. The rapid determination of ampicillin susceptibility allows optimal antibiotic selection for the treatment of Haemophilus influenzae infections with early discontinuation of potentially toxic supplementary drugs.

Ampicillin↗
PubMed1977

Early detection and preliminary susceptibility testing of positive pediatric blood cultures with the Steers replicator.

Early replicator subculturing of blood specimens after 4 to 16 h of incubation detected 135 of 217 (59%) of all positive cultures, including 56 of 64 (87%) Haemophilus influenzae type b, 7 of 22 (32%) Staphylococcus aureus, 19 of 20 (95%) pathogenic streptococci, and 20 of 24 (83%) Enterobacteriaceae. The mean time to detection of the common pediatric pathogens (36 h) was significantly less than that of contaminants (85 h) (P less than 0.001). Blind subculturing to differential media aided in the rapid identification of isolates and the detection of mixed cultures. In addition, a method of obtaining rapid susceptibilities of blood and body fluid isolates to selected antibiotics by blind subculturing to antibiotic-containing media was evaluated. Immediate susceptibility information was obtained for 214 of the 245 (87.3%) isolate-antibiotic combinations. There was complete correlation with a standard Kirby-Bauer reading for 94.9% of these observations. Replicator blood subculturing before 24 h of incubation results in early detection of the majority of pediatric pathogens. The inoculation of additional differential and antibiotic-containing media with each blind subculture aids in rapid identification of isolates and may give limited, but clinically important, immediate susceptibility information.

Anti-Bacterial Agents↗
PubMed1975

Rapid detection of bacteremia by an early subculture technic.

Routine blood cultures in a pediatric hospital were subcultured after 4 to 14 hours of incubation (average 8 hours). Eighty-five per cent of all significant, positive blood cultures were detected within 24 hours of initial incubation. Contaminant organisms rarely grew on early subculture plates. Compared with the traditional 24-hour or 48-hour stain and subculture technics, the 4--14-hour (early) subculture method allows more rapid detection, identification, and sensitivity testing of most bacteria isolated from clinically significant positive blood cultures.

Bacteriological Techniques↗