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Biomedical subjects

W L Wang

Publications and source records attributed to W L Wang.

At least 73 records · Page 4Linked to original sources
PubMed1986

Detection of pathogenic Campylobacter species in blood culture systems.

Because differences in recognition of Campylobacter fetus and Campylobacter jejuni in systemic infections may be due partially to differences in the ability to cultivate these organisms, we studied their growth characteristics in two widely used blood culture systems. In the Roche Septi-Chek system (Hoffman-La Roche, Inc., Nutley, N.J.), over a broad range of inocula all strains were detected in broth within 2 days and on paddles within 3 days. In the BACTEC 6B aerobic bottles (Johnston Laboratories, Inc., Towson, Md.), C. jejuni and C. fetus took a median of 5 and 3 days, respectively, to reach the growth index threshold. However, in the BACTEC 7D anaerobic bottles, C. fetus required a median of 2 days to reach the growth index threshold, whereas for C. jejuni the median was greater than 10 days. The poor performance of C. jejuni in both BACTEC systems may have been due to unfavorable incubation atmospheres and may partially explain why C. jejuni bacteremia is so infrequently detected. Overall, the Roche Septi-Chek system was excellent for detecting Campylobacter strains in blood cultures.

Aerobiosis↗
PubMed1986

[Ultrastructure of primary clear cell carcinoma of the liver].

Surgical specimens of 175 cases of primary hepatocellular carcinoma were prepared by routine paraffin section and HE stain. The clear cell cancer specimens were stained with PAS. All the specimens were observed by light microscope. Ultrathin sections were made for 50 samples and studied by electron microscope. Under the light microscope, 79 (45.1%) showed varying amounts of clear cells. According to the proportion and distribution of these cells, clear cell carcinoma of the liver was divided into three types: scattered type (16 cases, 20.3%), localized (43, 54.4%) and diffuse types (20, 25.3%). The clear cancer cells could be found in hepatoma with various degrees of differentiation. Of these 79 cases, 4 (5.1%) were grade I, 53 (67%) and 22 (27.9%) were grades II and III. Positive PAS stain gives an evidence of glycogen in the clear cell cytoplasm. 7 diffuse type clear cell hepatomas were observed with electron microscope. The cytoplasm had only fewer organelles, leading to a void appearance. The amount of the rough endoplasmic reticulum, free ribosome and polyribosome was markedly decreased. So was mitochondria, usually showing swelling and abnormality. The residual rough endoplasmic reticulum and mitochondria were out of normal arrangement. They often aggregated on one side of the nucleus or near the cell membrane. Glycogen particles were increased in some cell cytoplasms. Some particles were even and fine, some were aggregated into masses or scattered. Nuclei showed abnormalities mild to moderate. The nature of the clear cells in liver cancer is the variance of glycogen or lipid in the cytoplasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1985

Surveillance for the detection of nosocomial infections and the potential for nosocomial outbreaks. II. Development of a laboratory-based system.

We describe the development of a surveillance system that uses thresholds for detecting nosocomial infections and the potential for nosocomial outbreaks based on data from microbiology laboratory records at our hospital from 1980 to 1982. These records were monitored weekly to determine the number of positive isolates by the identity of the organism and by the site of the culture. A mean of 225 specimens was processed weekly, with 60 of these yielding bacteria or fungi. The average number of organisms isolated per positive culture was 1.46. Two methods of establishing thresholds were compared, one based on percentiles of ranked isolates, the other based on the mean plus intervals of standard error. The system using thresholds established by the standard error method was consistently more useful to highlight weeks for which there was high risk of a problem occurring in less time than were the surveillance techniques traditionally employed.

Colorado↗
PubMed1985

Controlled evaluation of supplemented peptone and Bactec blood culture broths for the detection of bacteremia and fungemia.

Comparison of conventional blood culture media with newer formulations of Bactec media for radiometric detection are lacking. Therefore, we compared the yield and speed of detection of clinically important microorganisms with supplemented peptone broth (SPB) and Bactec aerobic (6B) and anaerobic (7C or 7D) broths in 7,627 blood samples from adult patients. Acridine orange stains from SPB, radiometric readings from Bactec, and routine subcultures from all bottles were done at the same time intervals. Bactec grew more facultative gram-positive bacteria (P less than 0.02), Bacteroides spp. (P less than 0.001), gram-negative anaerobes (P less than 0.001). The two-bottle Bactec system required less time to detect Staphylococcus aureus (P less than 0.001), facultative gram-positive bacteria (P less than 0.001), Escherichia coli (P less than 0.02), facultative gram-negative bacteria (P less than .001), and fungi (P less than 0.001). Overall, Bactec yielded 11% more microorganisms and detected bacteremia sooner in 18% of samples than did SPB. This advantage was not because of radiometric monitoring, since most positive Bactec bottles were detected macroscopically. SPB offered no advantage for any group of microorganisms. We conclude that Bactec 6B and 7C or 7D broths used as a unit are superior to a single bottle of SPB with an equal volume of blood for the detection of bacteremia and fungemia, and that Bactec's superiority is not due to the method of detection.

Bacteria↗
PubMed1985

Controlled evaluation of Trypticase soy broth in agar slide and conventional blood culture systems.

A commercially available biphasic blood culture system that utilizes an attachable agar slide paddle and Trypticase soy broth (BBL Microbiology Systems, Cockeysville, Md.) was compared with a conventional Trypticase soy broth blood culture bottle in 6,867 paired blood cultures from adult patients. Both systems were inoculated with equal volumes of blood (5 ml) and incubated aerobically (vented) for 2 weeks. More clinically important bacteria and fungi, including Staphylococcus epidermidis, streptococci, Escherichia coli, Klebsiella spp., other Enterobacteriaceae, and Pseudomonas aeruginosa, were recovered from the biphasic system (P less than 0.001). In contrast, more anaerobic bacteria of importance were recovered in the conventional bottle (P less than 0.01). Staphylococci (P less than 0.001), gram-negative facultative and aerobic bacteria (P less than 0.001), and fungi (P less than 0.001) were detected 1 or more days earlier in the biphasic system, whereas pneumococci (P less than 0.05) were detected earlier in the conventional bottle. Of 603 clinically important microorganisms that grew in the biphasic system, 601 (99.7%) were detected by day 7 of incubation, but only 403 of 490 microorganisms (82.2%) were detected by day 7 in the conventional bottle. Overall, the biphasic system was superior to the conventional bottle. For optimal detection of anaerobic bacteremia, however, the biphasic system should be used in conjunction with a complementary anaerobic conventional bottle.

Bacteria↗
PubMed1985

Clinical comparison of an agar slide blood culture bottle with tryptic soy broth and a conventional blood culture bottle with supplemented peptone broth.

The Roche Septi-Chek biphasic blood culture system with tryptic soy broth was compared with a conventional blood culture bottle with supplemented peptone broth in 6,956 paired blood cultures from adult patients. Both systems were inoculated with equal volumes of blood (5 ml) and incubated aerobically (vented) for 2 weeks. More clinically important bacteria and fungi, including Staphylococcus aureus, S. epidermidis, Escherichia coli and other Enterobacteriaceae, Pseudomonas aeruginosa, and Candida albicans and C. tropicalis were recovered from the biphasic system (P less than 0.001). In contrast, more clinically important anaerobic bacteria (P less than 0.001) and Gardnerella vaginalis (P less than 0.05) were recovered in conventional supplemented peptone broth. Staphylococci (P less than 0.01), Enterobacteriaceae other than E. coli (P less than 0.05), and fungi (P less than 0.001) were detected 1 or more days earlier in the biphasic system, whereas streptococci (P less than 0.001) were detected earlier in the conventional bottle. The overall superiority of the agar slide blood culture system compared with conventional blood culture bottles was confirmed by this evaluation. For optimal detection of anaerobic bacteremia, however, the agar slide bottle should be paired with an anaerobic bottle.

Agar↗
PubMed1984

Killing of fabric-associated bacteria in hospital laundry by low-temperature washing.

Hospitals using 71.1 C water for laundering consume vast amounts of energy. We studied whether washing at 22 C would result in fabric-associated bacterial counts significantly different from those remaining after the high-temperature wash procedure in general use. Using a standard method to enumerate fabric-associated bacteria, we found that soiled sheets and terry cloth items were contaminated, respectively, with 10(6) and 10(8) cfu/100 cm2 of fabric area, predominantly gram-negative rods (especially Enterobacteriaceae and Pseudomonadaceae). Staphylococcus species were the most common gram-positive organisms. A standard low-temperature washing cycle without laundry chemicals removed 3 log10 of bacteria by agitation, dilution, and drainage. When low-temperature laundry chemicals were used, 3 log10 of bacteria were killed after the bleach was added, and sheets and terry cloth items had postwash colony counts of 10(1)-10(2) cfu/100 cm2. Drying removed an additional 1-2 log10 organisms. Bacterial counts and species from low- and high-temperature washed fabrics were comparable. Low-temperature washing is therefore as effective as high-temperature washing for eliminating pathogenic bacteria from hospital laundry.

Bacteria↗
PubMed1984

Comparison of antimicrobial susceptibility patterns of Campylobacter jejuni and Campylobacter coli.

To determine whether employing antibiograms is useful to separate Campylobacter jejuni and Campylobacter coli, we determined the MICs of 12 antibiotics for 104 human clinical strains and 74 swine strains. Of 74 swine strains, 5 (7%) were hippurate positive, as were 93 (89%) of 104 human strains. The 12 antimicrobial agents tested were ampicillin, amoxicillin, clindamycin, chloramphenicol, erythromycin, furazolidone, norfloxacin, nalidixic acid, rosoxacin, rosaramicin, tetracycline, and Sch 32063. Isolates from humans were significantly (P less than 0.001) more susceptible than swine strains to clindamycin, erythromycin, rosaramicin, and Sch 32063. Of 11 human hippurate-negative strains, 3 (27%) were resistant to clindamycin, erythromycin, rosaramicin, and Sch 32063, compared with 1 of 93 (1%) hippurate-positive strains. Nearly all human and swine strains were susceptible to furazolidone and nalidixic acid. Campylobacter isolates from humans and swine have different antibiograms, and the susceptibility to certain antibiotics, such as clindamycin, may be helpful for differentiation of C. jejuni from C. coli.

Animals↗
PubMed1984

Comparison of methods for recovery of Escherichia coli and Staphylococcus aureus from seeded laundry fabrics.

To assess the effect of laundry procedures on fabric-associated bacteria, a standard method of enumeration is needed. We evaluated six methods for enumeration of Escherichia coli and Staphylococcus aureus seeded (10(2) and 10(5) CFU/100 cm2 of fabric area) onto sterilized hospital sheets and terry . Two methods involved maceration of seeded swatches in broth followed by passage of the broth through a 0.45-micron-pore-size, 47-mm-diameter filter membrane. Three methods involved agitation of seeded swatches in broth with a paint shaker and membrane filtration of the broth to recover eluted bacterial cells, and the final method involved direct enumeration of cells on fabrics by overlaying seeded swatches with agar containing triphenyltetrazolium chloride as an indicator. The most convenient recovery method employed a 90-s agitation followed by serial dilution of broths and membrane filtration. This method provided 44/57% (low seed/high seed) recovery of E. coli from sheets and 133/31% from terry and 34/74% recovery of S. aureus from sheets and 58/57% from terry . Although maceration provided similar recovery of E. coli and S. aureus, it is a less-practical method. The direct enumeration method was ineffective for enumerating gram-positive bacteria. We conclude that either the agitation or maceration method used enumerated the seeded bacteria to within 1 log10 of their expected number and can be used to assess the bactericidal effectiveness of various steps in the laundering process.

Bacteria↗
PubMed1984

Role of stagnation and obstruction of water flow in isolation of Legionella pneumophila from hospital plumbing.

The stagnation of water in two of four hospital hot-water storage tanks found to contain Legionella pneumophila was reduced by keeping the two tanks continually on-line for 1 year. L. pneumophila colony counts in these two tanks fell quickly to low levels, whereas the organisms persisted in the two tanks that were not in use. L. pneumophila continued to be isolated from 50 to 100% of the hospital showerheads which were sampled during this period. We also examined aerators and other hospital faucet fixtures which obstruct water flow. L. pneumophila was isolated from 22 of 30 faucet aerators and 2 of 16 vacuum breakers but not from 26 nonobstructed faucets or 6 backflow preventers. Over a 7-month period, after nine faucet aerators were sterilized, 10 of 60 surveillance cultures revealed L. pneumophila, despite the inability to isolate the organism from the potable-water tanks in use. These data suggest that prevention of stagnation in hot-water tanks may be effective in reducing L. pneumophila concentrations in potable-water systems serving high-risk populations. We have also shown that faucet aerators, by providing a surface for L. pneumophila to colonize, can become secondary reservoirs for the organism in hospital plumbing.

Cross Infection↗
PubMed1984

Studies of Campylobacter jejuni in patients with inflammatory bowel disease.

Cultures, serology, and immunohistochemical tests for Campylobacter jejuni were performed on 74 patients with inflammatory bowel disease of various disease activity and in healthy and diseased control populations. Fecal cultures were negative in all groups tested. Antibodies to C. jejuni were assessed both by a complement fixation assay and an enzyme-linked immunosorbent assay to multiple serotypes of the organism. Antibody titers in inflammatory bowel disease patients and control populations were similar, and titers in these groups were significantly lower than in patients with acute Campylobacter enteritis. Intestinal tissues examined for Campylobacter antigens by an indirect fluorescent antibody assay were negative. These data do not etiologically implicate C. jejuni in Crohn's disease or chronic ulcerative colitis.

Antibodies, Bacterial↗
PubMed1983

Serologic study of two clusters of infection due to Campylobacter jejuni.

The serologic responses to Campylobacter jejuni in persons involved in two clusters of infection and in control subjects were studied. In the first cluster, in which previously unexposed persons drank raw milk, the attack rate was high and elevated complement-fixing (CF) and specific IgG and IgM antibodies were demonstrated. In the second cluster, involving farmers who chronically drank raw milk, the attack rate was low, but titers of CF and IgG antibodies were high in both affected and unaffected persons. At a control dairy farm, where raw milk was drunk regularly, asymptomatic infection and high CF titers were demonstrated. In contrast to the findings in the first cluster, the titers of IgM antibody among the dairy farmers were low. These studies suggest that chronic exposure to C. jejuni may lead to immunity that may possibly be mediated by IgG.

Adolescent↗