bluuebunny/crossref_metadata_2025 huggingface dataset:
Susceptibility of
Pseudomonas aeruginosa
to Gentamicin Sulfate In Vitro: Lack of Correlation Between Disc Diffusion and Broth Dilution Sensitivity Data
Authors: Traub Walter H.
Published: December 2020

Seventy-eight of 420 clinical isolates of
Pseudomonas aeruginosa
yielded zones of inhibition of less than 12 mm in diameter around 10-μg discs of gentamicin sulfate when tested by the standardized Bauer-Kirby disc diffusion method. Of 153 strains chosen from these isolates, one strain (0.65%) required 25 μg of gentamicin per ml for inhibition; the remainder (99.35%) were inhibited by 6 μg/ml or less of the antibiotic. It is recommended that those isolates of
P. aeruginosa
that yield zones of inhibition less than 12 mm in diameter be disc susceptibility-tested once more; those isolates that give zones of inhibition of less than 12 mm upon repeated examination should then be subjected to the broth dilution test before they are designated as sensitive or resistant to gentamicin.
Distribution of Coliphages in Hong Kong Sewage
Authors: Dhillon T. S. , Chan Y. S. , Sun S. M. , Chau W. S.
Published: December 2020

Coliphage content of sewage collected from 11 different localities in Hong Kong was determined. The number of plaque-forming units (PFU) ranged from 0.036 × 10
3
to 15.9 × 10
3
per ml. In general, urban sewage tended to be richer than rural sewage both in PFU count as well as plaque morphological variation. Seventy-seven isolates were subjected to a host range study. Fifty per cent of these were able to grow on
Escherichia coli
K-12 as well as
E. coli
B. Approximately 32% were found to be male specific, and the remaining 18% were K-12 specific although sex-indifferent.
Almond Harvesting, Processing, and Microbial Flora
Authors: King A. Douglas , Miller Mary Jo , Eldridge Linda C.
Published: December 2020

This survey was set up on a statistical sampling plan to determine the microbial quality of almonds as they are received at the processing plant. The total aerobic bacterial count and yeast and mold count distribution were skewed by a few high counts compared with the majority of relatively low counts. Hard shell varieties of almonds had lower counts than did soft shell, and almonds with complete shells had lower counts than shelled almonds. Almonds harvested onto canvas had lower counts than those harvested by knocking onto the ground. Nuts with the least amounts of foreign material mixed into the sample had the lowest counts, as did nuts with the least amount of insect damage. Coliforms,
Escherichia coli
, and
Streptococcus
were isolated from the nuts, and their presence was correlated with soil contamination. When almonds are stored, the total plate count, the
Streptococcus
count, and the
E. coli
count after an initial drop remain nearly constant for more than 3 months. In addition to the indicator organisms, several genera of bacteria were isolated including
Bacillus, Xanthomonas, Achromobacter, Pseudomonas, Micrococcus
or
Staphylococcus
, and
Brevibacterium
.
Interenvironmental Transfer of Microorganisms on the Exterior Surfaces of Jet Aircraft
Authors: Pfaender Frederic K. , Swatek Frank E.
Published: December 2020

The likelihood of microorganisms being transferred to new environments by jet aircraft was investigated. Initial random sampling of the aircraft surface revealed the presence of microorganisms in varying numbers on different aerodynamic surfaces. Bacteria of the genus
Bacillus
were the most common isolates, comprising approximately one-third of the total organisms found. The most frequently isolated fungi were
Cladosporium, Alternaria, Penicillium
, and several yeasts. Sampling of surfaces before and immediately after a flight demonstrated that microorganisms were collected during flight in areas protected from the airstream and lost in those areas directly exposed to it. These experiments also showed that the majority of the organisms contaminating the aircraft were acquired from the air at ground level. The placement of microorganisms on the aircraft surface before a flight and determination of their survival after flight indicated that the test organisms were most likely to be transported in the areas protected from the airstream. The organisms showing the best chance of being transferred seem to be the sporeforming bacteria, arthrospore-forming fungi, and some yeasts. All phases of this work showed that microorganisms could be carried by jet aircraft to environments they could not reach by natural means of dispersal.
Rapid Detection and Identification of Respiratory Viruses by Direct Immunofluorescence
Authors: D'Alessio Donn , Williams Stanley , Dick Elliot C.
Published: December 2020

The use of fluorescein-conjugated antiserum against respiratory syncytial (RS) and parainfluenza 1 and 3 viruses was compared with conventional techniques in the rapid detection of virus in tissue cultures inoculated with pharyngeal specimens known to contain these viruses. Twenty-three specimens were tested: 9 RS, 8 parainfluenza 1, and 6 parainfluenza 3. The fluorescent-antibody technique (FA) detected virus in 52% of the tissue cultures in 24 hr, and, by 72 hr, 22 of the 23 cultures were FA-positive whereas only 5 were positive by conventional techniques. Additionally, conjugated antisera were prepared against herpes simplex, influenza A
2
, and adenovirus type 5. All conjugates stained only the homologous virus and were 100- to 10,000-fold more sensitive than conventional techniques in detecting descending dilutions of virus inocula by 24 hr. With the procedures described, several antisera could be conjugated and ready for use within 24 hr. Serum fractionation was by ammonium sulfate precipitation, and with the procedure outlined virtually complete recovery of the globulin fraction and elimination of all of the albumin were accomplished.
Rapid Semiquantitative Method for Screening Large Numbers of Virus Samples by Negative Staining Electron Microscopy
Authors: Monroe James H. , Brandt Phillip M.
Published: December 2020

A rapid, semiquantitative method for screening large numbers of virus samples by negative staining electron microscopy is presented. Results obtained by this method are compared with results obtained by the pseudoreplica method and a measureddrop method. A figure is presented which represents the limit of detectability for virus by negative staining.
Rapid Detection of Sublethally Impaired Cells of
Enterobacteriaceae
in Dried Foods
Authors: Mossel D. A. A. , Ratto M. Alina
Published: December 2020

Samples of dried foods, feeds, and drugs were examined for
Enterobacteriaceae
by using buffered glucose-Brilliant Green-bile broth as the final enrichment medium and deep tubes of violet-red-bile-glucose-agar for confirmation. The pre-enrichment treatments used for the resuscitation of sublethally impaired cells were overnight incubation in lactose broth versus incubation for 1 to 6 hr at room temperature in shallow layers of tryptone soya peptone broth. The latter restoration treatment appeared to be significantly more productive.
Survival of
Neisseria gonorrhoeae
in the Mail
Authors: Cross Robert C. , Crecelius H. Gilbert , Counts Jon M.
Published: December 2020

Cultures of
Neisseria gonorrhoeae
, which used Thayer-Martin slants as transport medium, survived at least 1 day in the mail.
Pseudomonads and Achromobacters in the Spoilage of Irradiated Haddock of Different Preirradiation Quality
Authors: Laycock R. A. , Regier L. W.
Published: December 2020

The effect of initial quality of fish on postirradiation (100 krad) changes in the bacterial flora of haddock fillets during aerobic storage at 3 C has been investigated, with emphasis on the
Pseudomonas
and
Achromobacter
groups. The quality was related to the length of time the eviscerated fish had been stored in ice prior to filleting. Increased numbers of organisms, in particular
Pseudomonas putrefaciens
, were found initially on fillets cut from older fish. Pseudomonads were reduced by 2 to 3 log orders by irradiation, and achromobacters and gram-positive isolates predominated in the immediate postirradiation flora. Little difference could be detected in either types or relative proportions of organisms occurring during storage of unirradiated fish of different quality. Pseudomonads outgrew achromobacters and dominated the spoilage flora in all cases. After spoilage, however, the growth rate of pseudomonads declined markedly. In irradiated fish, achromobacters predominated throughout storage. In fish of better initial quality, bacterial numbers were 1 to 2 log orders higher at spoilage than in their unirradiated counterparts and in the poorer quality of irradiated samples. The increased number of organisms was accompanied by a radical change in the character of the predominant achromobacters. Pseudomonads were found to increase in numbers during storage of irradiated fish, in particular in poorer quality fish on which they were initially present in higher numbers. Detection of pseudomonads, even when present in high numbers, was found to be limited by the identification techniques normally used.
Modification of the Microtiter Technique for Antimicrobial Drug Susceptibility Testing by Incorporation of Indicators
Authors: Tippett L. O. , Zeleznick L. D. , Robb C. A.
Published: December 2020

A
p
H indicator and dextrose were incorporated into growth media as a modification of microbial microtiter methods for determining the minimal inhibitory concentration of antimicrobial drugs. This modified method was tested to evaluate the ease of reading end points by changes in the indicator color. Application of the procedure to two media, three indicators, and eight species of bacteria indicated that definitive end points could be reached as a result of indicator color change caused by acid production during bacterial growth. This method is accurate and reproducible. It is a modification which eliminates a need for plating and facilitates the reading of minimal inhibitory concentration end points.
Complement Fixation Reaction for the Diagnosis of Type II Avian (Marek's) Leukosis
Authors: Hamdy Farouk , Sevoian Martin
Published: December 2020

The present study was designed to find a complement fixation (CF) reaction for the diagnosis of type II lymphoid leukosis, to learn some of the characteristics of the CF antigen, and to investigate the development of CF antibody response to this infection. JM virus-specific antigen was demonstrated in tumorous chicken tissue, in JM virus-infected chick embryo material, in JM virus-infected chicken kidney, and in duck embryo fibroblast tissue culture by using JM virus-immune rabbit serum. This CF antigen did not show cross-reactivity with Rous sarcoma virus or with RIF-type viruses. It was partially heat-labile. The CF activity was restored at —70 C for 10 months and was resistant to intermittent freeze-thaw treatment. The CF antigen may be denatured by ethyl alcohol, but no significant deleterious effects were noted after ether or chloroform treatment. JM virus-specific CF antibody could not be demonstrated by the direct complement dilution method or by the indirect or inhibition form of the CF test in infected or immunized chicken sera.
Isolation of a Pure Dextranase from
Penicillium funiculosum
Authors: Chaiet L. , Kempf A. J. , Harman R. , Kaczka E. , Weston R. , Nollstadt K. , Wolf F. J.
Published: December 2020

A dextranase, produced by
Penicillium funiculosum
, was purified 1,000-fold to yield the enzyme which was demonstrated by gel electrophoresis and electrofocusing to be a homogeneous protein. The purification method included acetone partition, ammonium sulfate fractionation, gel filtration, iron defecation and precipitation, and diethylaminoethyl-cellulose chromatography. The pure enzyme was also obtained by preparative gel electrophoresis. Gel-permeation chromatography indicates a molecular weight of 41,000. An isoelectric
p
H of 4.6 was established by electrofocusing. A 1-mg amount of the enzyme hydrolyzes a dextran substrate to yield 27,000 isomaltose reducing units in 2 hr.
Laboratory Studies with a Selective Enterococcus Medium
Authors: Isenberg Henry D. , Goldberg Dorothy , Sampson Jane
Published: December 2020

Lancefield group D streptococci are involved with appreciable frequency in a variety of infectious processes. The presumptive recognition of these bacteria on initial culturing of clinical specimens is an objective not attained readily by selective media available in the clinical laboratory. Selective Enterococcus agar was evaluated with emphasis on its ability to sequester enterococci from specimens with many microbial components. In addition, the sensitivity of this new agar was compared with Trypticase Soy agar containing sheep blood and Mitis Salivarius agar. All enterococci isolated from clinical material were classified in accordance with accepted biochemical and immunochemical criteria. The enterococci grew on the new medium as distinctive colonies surrounded by a black zone. Only
Listeria monocytogenes
presented similar colonial morphology after 48 hr. Most other bacteria did not grow at all or appeared markedly different. The sensitivity of the new agar was of the same order of magnitude as on blood or Mitis-Salivarius agars, but its selectivity was superior.
Oxidation-Reduction Potential and Growth of
Clostridium perfringens
and
Pseudomonas fluorescens
Authors: Tabatabai L. B. , Walker H. W.
Published: December 2020

A new apparatus was developed for measuring changes in
E
h
,
p
H, and cell numbers. With this apparatus, the relationships of these parameters were studied at initial
E
h
levels of 200 and 40 mv (
p
H 7.0), by using
Clostridium perfringens
and
Pseudomonas fluorescens
. One of the strains of
C. perfringens
grew more luxuriantly at the higher
E
h
, in the presence of small quantities of oxygen, than at the lower one in the absence of oxygen.
P. fluorescens
could grow at a relatively low
E
h
(40 mv,
p
H 7.0) in pure culture but not in the presence of
C. perfringens
under the same conditions.
Stability of Antibiotics and Chemotherapeutics in Agar Plates
Authors: Ryan Kenneth J. , Needham Gerald M. , Dunsmoor Carol L. , Sherris John C.
Published: December 2020

The stability of chemotherapeutic agents incorporated into agar plates was studied by comparison of minimum inhibitory concentrations on fresh and stored plates and by direct bioassay of the chemotherapeutic agar plates. Plates were stored in sealed bags at 4 C. No loss of bioactivity was demonstrated after 30 days of storage in plates containing methicillin, erythromycin, cephalothin, tetracycline, chloramphenicol, kanamycin, streptomycin, polymyxin B, or nalidixic acid. Penicillin G, ampicillin, and nitrofurantoin showed statistically significant losses of activity after 4 weeks. None of the chemotherapeutics tested showed significant loss in activity after 1 week.
Environmental and Nutritional Factors Affecting the Production of Rubratoxin B by
Penicillium rubrum
Stoll
Authors: Hayes A. Wallace , Wyatt Elwanda P. , King Patricia A.
Published: December 2020

Rubratoxin B can be produced in a semisynthetic medium by
Penicillium rubrum
under varying environmental and nutritional conditions. Maximum production (552.0 mg/500 ml) was obtained with
P. rubrum
NRRL A-11785 grown in stationary cultures of Mosseray's simplified Raulin solution supplemented with 2.5% malt extract broth at ambient temperature. Zinc is required at levels of at least 0.4 mg per liter. In the absence of iron sulfate, there was a 50-fold reduction in rubratoxin B production but not in growth. No toxin was produced by this isolate in 5- or 7-liter fermentors.
Evaluation of the Edgegard Laminar Flow Hood
Authors: Coriell Lewis L. , McGarrity Gerard J.
Published: December 2020

In a horizontal back-to-front flow high-efficiency particulate air-filtered laminar hood, it is shown that a Blake bottle obstruction to the air flow causes a downstream cone of turbulent air which can draw microbial contamination into the work area of the hood. In controlled experiments, contamination with T3 coliphage was reduced by a series of perforations around the open edge of the hood which eliminates the cone of turbulent air. The average reduction in phage counts was 90.75, 86.79, 91.12, and 98.92%, depending upon the site of nebulization. The phage counts were reduced in 48 of the 51 tests.
Isolation of Fluorescent Pseudomonads with a Selective Medium
Authors: Sands D. C. , Rovira A. D.
Published: December 2020

Incorporation of novobiocin, penicillin, and cycloheximide into a standard medium for fluorescence selects for fluorescent pathogenic and free-living pseudomonads.
Microbial Aromatization of Androsta-1, 4, 7- Triene-3, 17-Dione
Authors: Kluepfel Dieter , V�zina Claude
Published: December 2020

Several microorganisms transform androsta-1, 4, 7-triene-3, 17-dione into equilin and equilenin, presumably via a 19-hydroxylated intermediate.
Characterization of EO-1 Strains (
Pseudomonas kingii
) Isolated from Clinical Specimens and the Hospital Environment
Authors: Gilardi G. L.
Published: December 2020

Ten strains of the pseudomonad designated EO-1 and named
Pseudomonas kingii
, which were isolated from clinical specimens and the hospital environment, are described.
Recovery of a Canine Herpesvirus from Primary Kidney Cultures Derived from a Closed Dog Colony
Authors: Smith R. F. , Yamashiroya H. M. , Magis J. M.
Published: December 2020

The recovery of a canine herpesvirus from one of eight lots of primary canine kidney cultures derived from a closed dog colony is reported.
Rapid Procedure for the Detection of Acid and Gas Production by Bacterial Cultures
Authors: Fung Daniel Y. C. , Miller Richard D.
Published: December 2020

A rapid miniaturized procedure, with a Microtiter plate and the Amojell-overlay technique, is described for the detection of acid and gas production by bacterial cultures.

Images
Improved Tissue and Cell Homogenizer
Authors: Zierdt Charles H. , Norris George F.
Published: December 2020

Modification of an existing tissue homogenizer is described, which converts to a milk-like consistency even difficult to macerate tissues such as cartilage, hair, and small bones.
Escherichia coli
with Resistance Factors in Vegetarians, Babies, and Nonvegetarians
Authors: Guinée P. , Ugueto N. , van Leeuwen N.
Published: December 2020

The prevalence of
Escherichia coli
carrying resistance factors (R factors) was examined in meat-consuming individuals and in those not consuming meat (vegetarians and babies below the age of 6 months). Assuming that the transport of resistant
E. coli
from animals through meat and meat products to the human consumer is most important, with regard to the incidence of resistant
E. coli
in man, we expected a significant difference in the proportions of people with resistant
E. coli
between the two groups. However, the percentage with resistant
E. coli
was larger in the group of vegetarians and babies than in the group of meat-eating individuals.
Characteristics of Growth Inhibition of
Lactobacillus casei
by 4-Nitroquinoline-
n
-Oxide
Authors: Bond T. J. , Young Kamie Law , Andrus Teresa Tarbell
Published: December 2020

The bacteriostatic action of 4-nitroquinoline-
n
-oxide (4-NQO) for
Lactobacillus casei
is substantially reversed by
d
-and
l
-cysteine, glutathione, and 2,2-dihydroxy-1,4-dithiolbutane (dithioerythritol). The action appears to involve a chemical reaction between carbon atom 4 of 4-NQO and nucleophilic centers, such as -SH groups, located on essential cell constituents. The evidence presented indicates that the protective effect of
d
- and
l
-cysteine, glutathione, and dithioerythritol against the action involves reactions between 4-NQO and -SH compounds.
Urease Color Test Medium U-9 for the Detection and Identification of “T” Mycoplasmas in Clinical Material
Authors: Shepard Maurice C. , Lunceford Carl D.
Published: December 2020

A urease color test fluid medium (U-9) for the detection and identification of T (T-strain) mycoplasmas in clinical material is described which is sensitive and specific for this group of mycoplasmas. The medium was prepared from commercially available components and contained 95% half-strength, tryptic digest broth (
p
H 5.5), 4% unheated horse serum, 0.05% highest-purity urea, 0.001% sodium phenolsulfonphthalein, and 1,000 units of potassium penicillin G per ml. The final reaction of medium U-9 was
p
H 6.0. The overall agreement (positive and negative) between urease reactions in U-9 urease color test medium and culture findings in a standard agar primary culture system among 686 clinical specimens was 98.1%. The disagreement consisted of 13 false-positive urease reactions which were recognized visually as false-positive reactions due to other microorganisms. For specimens from the female genitourinary tract, the inclusion of 2.5 μg of amphotericin B (Fungizone) per ml of medium U-9 is recommended for the suppression of growth of
Candida
species and filamentous fungi.
Enhancement of Friend Leukemia Virus Infection in Mice by Guaroa Virus: Quantitation and Action of Various Oncogenic and Nononcogenic Viruses
Authors: Spahn Gerard J. , Turner W. , Peters Robert L. , Chirigos Michael A.
Published: December 2020

Previous studies have indicated that Guaroa virus (GV), an arbovirus, enhanced the replication of Friend leukemia virus (FLV) in mice. To study further the interaction of GV and FLV, different levels of FLV activity were inoculated into mice. At a level of activity capable of producing limited splenic response, coinfection with GV resulted in a marked increase in spleen-foci activity, mean spleen weight, and amount of infectious virus recoverable from plasma and spleen of dually infected mice. Various oncogenic and nononcogenic viruses were also tested for their ability to enhance FLV infection.
Gastrointestinal Bacteria of Certain Antarctic Birds and Mammals
Authors: Soucek Z. , Mushin Rose
Published: December 2020

An investigation was carried out of the aerobic gram-negative intestinal flora of 158 penguins, 30 skuas, and 66 seals from the Antarctic and sub-Antarctic zones and Phillip Island. Among penguins and seals, 17% and 11%, respectively, were devoid of aerobic enteric organisms, but microscopic examination showed the presence of other bacteria. The coliforms outnumbered the paracolons and nonlactosefermenting bacteria; irregular coliform types and
Escherichia coli
were predominant. The present study indicated the effect of diet on the composition of the intestinal flora of the birds and mammals examined.
Dry-Heat Inactivation Kinetics of Naturally Occurring Spore Populations
Authors: Bond W. W. , Favero M. S. , Petersen N. J. , Marshall J. H.
Published: December 2020

Twenty-three soil samples were collected from areas of the United States where major spacecraft assembly and launch facilities are in operation. Soil samples were treated with ethyl alcohol, ultrasonic energy, and gross filtration. The resultant suspensions consisted of viable, naturally occurring bacterial spores and were used to inoculate stainless-steel strips. The strips were suspended in a forced air oven and assays were made at 5-min intervals for the number of viable spores. Most survivor curves were nonlinear. Subsequently, spore crops of heat-sensitive and heat-resistant soil isolates were found to have linear survivor curves at 125 C which were unaffected by the presence or absence of sterile soil particles from the parent sample. When two spore crops, one of which was heat-resistant and the other heat-sensitive, were mixed, the resultant nonlinear curves were unaffected by the presence or absence of sterile parent soil. Therefore, the survivor curves obtained originally with the soils were the result of heterogeneous spore populations rather than of protection afforded by soil particles in our test system. These results question the rationale both of assuming logarithmic death and of using decimal-reduction values obtained with subcultured standard reference spores in the derivation of dry-heat sterilization cycles for items contaminated with naturally occurring spore populations.
Microbiological Assay for Estimating Salivary Concentrations of the Cariostatic Antibiotic Actinobolin
Authors: Hunt D. E. , Bradley E. L. , Bachmann Joan W.
Published: December 2020

A logarithmic-ratio microbiological assay has been developed for the estimation of concentrations of actinobolin (or inhibitory equivalents) in human saliva. The utility of this assay has been demonstrated by presenting data that show concentrations of this antibiotic (or inhibitory equivalents) detected in saliva or saline after incubation at 37 C for periods as long as 6 hr. The results of some statistical analyses of the assay data have been included.
In Vitro Susceptibility of
Brucella
to Various Antibiotics
Authors: Hall Wendell H. , Manion Robert E.
Published: December 2020

A series of 27 strains of six species of
Brucella
was tested for susceptibility in vitro to a representative cross section of antibiotics in current use. The activity against each species was plotted, with the cumulative per cent of strains inhibited indicated for each concentration. As a class, the tetracycline antibiotics were the most effective. Erythromycin, gentamicin, streptomycin, and kanamycin, as well as rifampin, were quite active. The penicillin-cephalosporin group, with the exception of ampicillin, was comparatively ineffective, as were the polypeptides and the miscellaneous group of chloramphenicol, lincomycin, cycloserine, and sulfadiazine. Species differences were noticeable, with some strains of
B. canis
being considerably more resistant to streptomycin and the tetracyclines than
B. suis
and
B. abortus. B. melitensis, B. ovis
, and
B. neotomae
were intermediate in antibiotic susceptibility.
Bacterial Degradation of Diphenylmethane, a DDT Model Substrate
Authors: Focht D. D. , Alexander M.
Published: December 2020

A strain of
Hydrogenomonas
was isolated by elective culture in a solution with diphenylmethane, an analogue of DDT, as the sole carbon source. Constitutive enzymes effected the oxidation and fission of one of the benzene rings of diphenylmethane, and phenylacetic acid was found as a major degradation product. Small amounts of phenylglyoxylic and benzoic acids were also generated from diphenylmethane by the bacterium. Phenylacetic acid, which contains the second benzene ring of diphenylmethane, was metabolized by inducible enzymes.
Effect of Relative Humidity on the Penetrability and Sporicidal Activity of Formaldehyde
Authors: Hoffman Robert K. , Spiner David R.
Published: December 2020

The effect of relative humidity (RH) on formaldehyde penetration of paper, glassine, and cotton was determined by the death rate of bacterial spores in glass tubes covered with these materials. The data show that paper is readily penetrated regardless of RH, but the RH greatly affects the penetration rate of glassine and cotton. A comparison was also made of the effect of RH on the penetrability of formaldehyde generated from Formalin and paraformaldehyde. At low RH, all three closures were penetrated more readily by formaldehyde from paraformaldehyde than from Formalin, but no difference in the two was observed at high RH. It is felt that the difference at low RH is primarily due to the condensation of the vaporized Formalin.
Determination of Niacin in Orange Juice with Lyophilized
Lactobacillus arabinosus
ATCC 8014
Authors: Gorin N. , Meulenhoff E. J. S. , Yarrow D.
Published: December 2020

The determination of niacin in orange juice with lyophilized
Lactobacillus arabinosus
ATCC 8014 has the advantage over the usual method in eliminating the delay caused by the necessity of cultivating cells of
L. arabinosus
for the inoculum and also in eliminating the periodical cultivation on agar slopes.
Hanging Magnetic Stirrer Which Minimizes Cell Disruption
Authors: Bungay H. R.
Published: December 2020

A magnetic stirring bar enclosed in tubing forms a large paddle which produces good mixing at slow rotational speeds. It is suspended above the bottom of the vessel and cannot grind cells or become misaligned.
Metabolic Fate of Cysteine and Methionine in Rumen Digesta
Authors: Nader C. J. , Walker D. J.
Published: December 2020

Estimates were obtained of the extent to which cysteine and methionine were incorporated into the protein of the microbes of rumen digesta without prior degradation and resynthesis. By using the amino acids labeled with both
35
S and
14
C, it was observed that a large proportion of the
35
S appeared in the sulfide pool and of the
14
C appeared in volatile fatty acids. By isolating the appropriate amino acid, obtaining the
14
C to
35
S ratio, and comparing this with the ratio in the added amino acid, the degree of direct incorporation was calculated. For cysteine it was estimated that at most 1% and for methionine, at most 11% of the amino acid in the free pool was incorporated unchanged into microbial protein. As a consequence of these findings, it is considered that the method for measuring microbial protein synthesis in rumen digesta based upon incorporation of
35
S from the free sulfide pool is not seriously affected by direct utilization of sulfur amino acids arising from dietary sources.
Sugar Substrates for
l
-Lysine Fermentation by
Ustilago maydis
Authors: Sánchez-Marroquín A. , Ledezma M. , Carreño R.
Published: December 2020

The extracellular production of
l
-lysine in media with cane sugar, blackstrap molasses, or clarified sugar-cane juice by a previously obtained mutant of
Ustilago maydis
was studied. Enzymatically inverted clarified juice (medium J-3) gave 2.9 g of lysine per liter under the following conditions: inoculum, 5%;
p
H 5.8; temperature, 30 C; K
La
in the fermentors, 0.41 mmoles of O
2
per liter per min; fermentation time, 72 hr. The concentrate, obtained by direct evaporation and drying of the fermentation broth, could be used as a possible feed supplement because of its amino-acid and vitamin content.
Quantitation of the Antigenicity and Immunogenicity of Purified Foot-and-Mouth Disease Virus Vaccine for Swine and Steers
Authors: Morgan D. O. , McKercher P. D. , Bachrach H. L.
Published: December 2020

The antigenicity and immunogenicity of a purified preparation of foot-and-mouth disease virus [type A
12
, strain 119 (FMDV A-119)] inactivated with 6.0 m
m
N
-acetylethylenimine at 37 C were compared in swine and steers. Three antigen doses were tested, 640, 160, and 40 ng. In accordance with findings for guinea pigs, as previously determined by dose-response curves, as little as fourfold changes in antigen in the region of the minimum effective dose produced marked differences in the serological and immune responses of swine. The minimum effective dose of antigen for antibody formation in swine and guinea pigs, as determined by mouse median protective dose (PD
50
) values, was 160 ng. The minimum immunogenic dose for swine was also 160 ng. The vaccinated swine were challenged with either FMDV A-119 or with heterologous subtype A
24
strain Cruzeiro or type A strain A-CANEFA-1. Those immunized with 640 ng of antigen were about equally immune to the three challenge viruses; most swine having a mouse PD
50
value of 2.0 or greater were immune regardless of which strain was used for challenge. In steers, the smallest dose tested, 40 ng, was satisfactory in eliciting circulating antibodies and immunity. Physical and biological tests indicated that the antigen used in the vaccine is stable for at least 9 months at 4 C.
Ethylene Oxide Resistance of Nondesiccated and Desiccated Spores of
Bacillus subtilis var. niger
Hermetically Sealed in Various Polymeric Films
Authors: Doyle John E. , McDaniel Alvin W. , West Keith L. , Whitbourne James E. , Ernst Robert R.
Published: December 2020

The resistance to destruction of spores of
Bacillus subtilis
var.
niger
hermetically sealed in various polymeric films and exposed to ethylene oxide with and without relative humidity was determined. The effect of desiccation was also determined. The order of increased resistance to sterilization with regard to type of polymeric film was found to be: polyethylene equal to polyvinyl chloride, less than nylon, less than cellophane/polyethylene laminate, less than phenoxy, less than mylar/polyethylene laminate. Desiccated spores sealed in various polymeric films were much more resistant to ethylene oxide sterilization than nondesiccated spores. Relative humidity was an important factor in ethylene oxide sterilization with spores not sealed in polymeric films. However, with spores hermetically sealed in polyethylene, added relative humidity was an insignificant factor in the sterilization process.
Sterility Test Method for Petrolatum-Based Ophthalmic Ointments
Authors: Tsuji Kiyoshi , Stapert E. M. , Robertson John H. , Waiyaki Peter M.
Published: December 2020

A sensitive sterility testing procedure for the detection of microbial contamination in petrolatum-based ointments is described. The method involves dissolving the ointment in filter-sterilized isopropyl myristate and filtering through a membrane filter. Improved sensitivity is obtained by blending the membrane in Trypticase Soy Broth before incubation. Filter-sterilized isopropyl myristate is shown to be less toxic to microorganisms than heat-sterilized isopropyl myristate. The isopropyl myristate method is more sensitive than the polyethylene glycol-ether method for the detection of microbial contamination.
Probability Distribution of Drug-Resistant Mutants in Unselected Populations of
Mycobacterium tuberculosis
Authors: David Hugo L.
Published: December 2020

The fluctuation test shows that
Mycobacterium tuberculosis
mutates to resistance to isoniazid, streptomycin, ethambutol and rifampin spontaneously and at random. The average mutation rates for the drugs, in the same order, were calculated to be 2.56 × 10
−8
, 2.95 × 10
−8
, 10
−7
, and 2.25 × 10
−10
mutation per bacterium per generation. The relatively high mutation rate to ethambutol resistance and the low mutation rate to rifampin resistance were confirmed by analyzing the increase in the proportion of mutants with time in a growing population of the tubercle bacilli. The highest proportions of mutants to be expected in unselected populations of the tubercle bacilli were calculated from the results of fluctuation tests.
Serological Diagnosis of Human Melioidosis with Indirect Hemagglutination and Complement Fixation Tests
Authors: Alexander Aaron D. , Huxsoll David L. , Warner Albert R. , Shepler Virginia , Dorsey Arthur
Published: December 2020

An indirect hemagglutination (IHA) test and a complement fixation (CF) test were evaluated from test results on sera from 212 human melioidosis patients of which 119 were culturally proved cases. Significant antibody titers (IHA titers of 1:40 or greater and CF titers of 1:4 or greater) were demonstrated with either test in all except five patients. IHA and CF titers ranged as high as 1:20,480 and 1:1,024, respectively. Antibodies were usually demonstrated by both tests 1 week after onset of disease. Transient seronegative reactions during the course of disease were seen in sera of approximately 19% of the patients with either IHA and CF but rarely with both tests. High titers in either test were obtained by the third week of disease and reached maximum levels in 4 to 5 months. Titers usually were detectable for 9 or more months. Antibodies were detected by IHA and CF tests in 80 to 100% of the sera obtained at various time intervals from 9 months to 2 or more years after disease onset. Antibody persistence occurred in patients who had a short disease course, as well as in patients with prolonged, complicated infections. The IHA test had excellent specificity when evaluated with normal human sera and diverse antimicrobial sera from hyperimmunized rabbits and human patients. The CF antigen appeared to contain common antigens with some but not all types of
Pseudomonas aeruginosa
. The specificity of the CF antigen could be enhanced without appreciable effect on its sensitivity by use of a titer of 1:8 in lieu of 1:4 as a criterion for a significant reaction. Either test could be used advantageously for the laboratory diagnosis of melioidosis.
Effect of Sodium Fluorescein and Plating Medium on Recovery of Irradiated
Escherichia coli
and
Serratia marcescens
from Aerosols
Authors: Dorsey Emerson L. , Berendt Richard F. , Neff Everett L.
Published: December 2020

Irradiation of aerosols of either
Escherichia coli
or
Serratia marcescens
with simulated solar (xenon) radiation caused a significant decrease in viability. When sodium fluorescein was employed to determine the physical loss of organisms from the aerosol, an additional adverse effect upon survival was noted. The decay curves indicated that at least two mechanisms of inactivation were operative, one due to aerosolization, the other to irradiation. After collection from aerosols, both species of microorganisms grew better on blood agar base than on Casitone agar, but this finding did not appear to be related to the effect of irradiation.
Detection of Mycotoxins by Thin-Layer Chromatography: Application to Screening of Fungal Extracts
Authors: Scott P. M. , Lawrence J. W. , van Walbeek W.
Published: December 2020

A convenient thin-layer chromatographic screening procedure for the detection of 18 mycotoxins is described.
Continuous Dispenser for Multiple-Well Serological Plate
Authors: Middlebrook G. , Reggiardo Z. , Taylor G. R.
Published: December 2020

Materials and methods are described for the construction of an inexpensive multiple-well dispensing apparatus for use in serological microtitration.
Standardization of Human Diploid Cell Cultivation
Authors: Litwin Jack
Published: December 2020

Human embryonic diploid lung fibroblasts grown in Eagle's medium were exposed continually to a variety of environmental conditions over a large number of passages to observe how these conditions affected the growth and longevity of these cells in vitro. The cells grew well at temperatures between 34 and 37 C and some cells could be adapted to grow at 40 C. Very limited growth occurred at 30 to 31 C; however, confluent monolayers of cells could be maintained for months at 30 C and still give rise to actively growing cultures. Increasing the amino acid concentration in Eagle's medium or the calf serum concentration above 10% had no effect on the growth rate or longevity. One per cent calf serum could not support prolonged active growth. Trypsin concentrations between 1 and 0.1% and crystalline trypsin at 50 μg/ml showed no influence on cell growth. Ethylenediaminetetraacetic acid treatment and scraping, however, destroyed many of the cells, and the survivors grew poorly. The clonal morphology varied with age. Young cells frequently gave rise to densely packed clones, whereas older cells gave rise to clones with widely scattered cells. The cloning efficiency was high when the cells were young but decreased rapidly with successive passage. It was relatively constant from the 7th to 20th passage at about 15%.
Neutron Activation Analysis of Manganese and Sodium in Bacterial Cells
Authors: Krueger Woodrow B. , Carey Walter E. , Kolodzeij Bruno J.
Published: December 2020

The application of neutron activation analysis for mineral determinations in bacteria was investigated. Elements considered here were manganese and sodium. The sporeformer
Bacillus megaterium
ATCC 19213 was utilized. With this method, the manganese and sodium levels of whole and ashed vegetative cells, sporulating cells, and free spores were determined. The culture medium was also analyzed for these two elements. The results indicate that neutron activation analysis is readily applicable to the study of mineral content of bacterial cells, spores, and culture media. The method has been shown to be ideal for the study of incorporation and egression of mineral elements during vegetative growth and secondary metabolism of sporulation.
Immunization of Mice with Components of
Pasteurella multocida
Authors: Srivastava Kunwar K. , Foster John W. , Dawe Donald L. , Brown John , Davis Richard B.
Published: December 2020

Log-phase cells of
Pasteurella multocida
strain P-1059 were used to prepare isolated culture filtrate, cell wall, and cytoplasmic components. Culture filtrate was further separated by column chromatography. A portion of cytoplasm and culture filtrate was conjugated to ferritin by means of metaxylylene diisocyanate. Cell walls induced more protection in mice than the conjugated or unconjugated cytoplasm or culture filtrate. The cell walls caused edema and erythema when given intradermally in rabbits, whereas cytoplasm and culture filtrate produced dermal necrosis. The first of four chromatographically separated fractions of culture filtrate was possibly more immunogenic in mice than cell walls. This fraction was less reactive intradermally in rabbits than cell walls but more reactive than the other fractions.
Pyrolysis-Gas-Liquid Chromatography of Fungi: Differentiation of Species and Strains of Several Members of the
Aspergillus flavus
Group
Authors: Vincent Phillip G. , Kulik Martin M.
Published: December 2020

Four fungi of the
Aspergillus flavus
group were differentiated to the species level and strain level by pyrolysis-gas-liquid chromotography. Comparisons of pyrochromatograms revealed more similarities than dissimilarities among both species and strains in the pyrolytic elution patterns. Quantitative analysis was made by comparing the number of peaks in which two strains or reference species agreed or disagreed, the degree of superimposability between the pyrolytic elution patterns of strains and reference species, and the presence or absence of peaks for strain pairs within each species. The accuracy and precision of these techniques suggest that pyrolysis-gas-liquid chromatography may have wide application in the detection, enumeration, and identification of fungi by nonmycologically trained personnel.
Improved Device for the Administration of Fungal Spores to Small Animals via the Respiratory Route
Authors: Burrell Robert
Published: December 2020

An improved device has been designed and constructed for the administration of fungal spores or other air-suspended particles to mice via inhalation. Fabricated from Lucite [0.25 inch (0.63 cm)], the device was built in the shape of a 6-inch (15.2-cm) cube with two 1-inch (2.5-cm) holes drilled in each side. Mice are restrained in plastic conical centrifuge tubes which fit into the holes by friction. The device is safe, easily cleaned and sterilized, and can accommodate up to eight animals at a single exposure.
Technique for Viral Neutralization Antibody Surveys in Primary Microcultures
Authors: Helmke R. J. , Heberling R. L. , Kalter S. S.
Published: December 2020

A simplified, microplate tissue culture procedure is described which facilitates neutralization antibody surveys on large numbers of sera. A comparison of the micromethod with that employing standard tube cultures indicates it to be as sensitive and far more economical.
Method for the Isolation of Proteolytic Marine Bacteria
Authors: Sizemore Ronald K. , Stevenson L. Harold
Published: December 2020

A two-layer plate consisting of a lower indicator layer of milk-agar and an upper nutrient agar layer was developed for isolating proteolytic marine bacteria.
Foot-and-Mouth Disease Virus Antibodies: Comparison of a Tissue Culture Microneutralization Test with the Assay in Suckling Mice
Authors: Wagner G. G. , McVicar J. W.
Published: December 2020

A microneutralization test for foot-and-mouth disease virus antibodies is described and compared to the standard mouse test.
Improved Chemically Defined Basal Medium (CMRL-1969) for Primary Monkey Kidney and Human Diploid Cells
Authors: Healy G. M. , Teleki S. , Seefried A. V. , Walton M. J. , Macmorine H. G.
Published: December 2020

An improved tissue culture basal medium, CMRL-1969, supplemented with serum, has been evaluated by measuring the growth responses of primary cultures of trypsin-dispersed monkey kidney cells (PMKC) and of an established culture of a human diploid cell strain (HDCS). Medium H597, an early modification of medium 199 which has been used successfully in the preparation of poliomyelitis vaccine for 15 years, was used for comparison. In addition, parallel testing was done with Basal Medium Eagle (BME) widely used for the growth of HDCS. The improvements in basal medium CMRL-1969 are attributed to changes in amino acid concentrations, in vitamin composition, and, in particular, to enhanced buffering capacity. The latter has been achieved by the use of free-base amino acids and by increasing the dibasic sodium phosphate. The new medium has already been used to advantage for the production of polioviruses in PMKC where equivalent titers were obtained from cultures initiated with 70% of the number of cells required with earlier media. The population-doubling time was reduced in this system. Also, with small inocula of HDCS, the time required to obtain maximum cell yield was shorter with CMRL-1969 than with BME. Both media were supplemented with 10% calf serum. Maximum cell yields after repeated subcultivation in the new basal medium were greatly increased and the stability of the strain, as shown by chromosomal analysis, was not affected. Basal medium CMRL-1969 can be prepared easily in liquid or powdered form.
Micro Indirect Hemagglutination Test for Cytomegalovirus
Authors: Fuccillo David A. , Moder Flora L. , Traub Renee G. , Hensen Sally , Sever John L.
Published: December 2020

In an effort to obtain the flexibility and ease of performance of a rapid, serological test for detection of cytomegalovirus antibody, the indirect hemagglutination (IHA) technique was investigated by using a microserological system. Antigens were prepared from tissue cultures of infected human fibroblasts. The specificity of the cytomegalovirus antibody response detected by the IHA test correlated well with the standard neutralization test. The IHA method was more sensitive than the complement fixation test in detecting antibody in congenitally infected newborns. There appeared to be some heterologous antibody response with
Herpesvirus hominis
or varicella virus infections. The IHA test pattern was found to be very stable with excellent persistence of agglutination.
Rapid Method for the Isolation of
Listeria monocytogenes
from Experimentally Infected Mice
Authors: Wilkinson Thomas R. , Hall Elizabeth R.
Published: December 2020

Listeria monocytogenes
was successfully isolated from experimentally infected mice by placing homogenized tissues in phosphate-buffered saline (PBS), trypsin, peptone, or pepsin followed by incubation at 37 C for 24 hr. A larger number of
Listeria
isolates were recovered from the trypsin or PBS splenic homogenate suspensions incubated at 37 C for 2 hr than from the other diluent suspensions. Holding infected tissues at 4 C for at least 3 months did not increase the efficiency of
Listeria
isolation.
Listeria
L-forms were not isolated from mice injected with the bacterial form. The in vitro viability of
Listeria
L-forms suspended in PBS or PBS splenic homogenate was greatly reduced when held at 4 C.