bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzyme-linked immunosorbent assay for rubella immunoglobulin G: new method for attachment of antigens to microtiter plates
Authors: Skurrie I J , Gilbert G L
Published: January 2020

Many of the enzyme-linked immunosorbent assay (ELISA) techniques previously described for detection of rubella-specific antibodies employ complex technology not available in routine diagnostic laboratories. The method described allows the use of commercially available rubella hemagglutination inhibition (HI) antigen. Passive adsorption of these antigens to plastic is variable, but with the use of albumin as a bridge, it is possible to attach the antigen reliably to the plastic wells. Over 1,500 sera were tested by both HI and ELISA techniques to detect the presence of rubella antibodies. These sera were selected with a bias towards those with low levels of rubella-specific antibody, since it has been demonstrated that it is in this range that discrepancies are more likely to occur between HI and ELISA techniques. In 99% of the sera tested, the results of both techniques were in agreement. On the basis of these results, the technique offers a useful alternative to the routine rubella HI test and other ELISA techniques which need sophisticated antigen preparations.
Factors affecting detection of Yersinia enterocolitica heat-stable enterotoxin by the infant mouse test
Authors: Serafim M B , Monteiro A R , de Castro A F
Published: January 2020

With regard to the assay of heat-stable enterotoxin (ST) from Yersinia enterocolitica, we made a comparative study of the conventional infant mouse test read at 4 h and a modified infant mouse test read at 2 h. The influence of several factors, such as the medium used to prepare ST, lysing of bacterial cells from the broth cultures used to prepare ST, and the temperature at which the inoculated mice were kept during the test, was also investigated. Thus, with a few exceptions, Pai-Mors medium was more suitable than Casamino Acids-yeast extract medium, for the preparation of yersinial ST. Gut/carcass weight ratios obtained with lysed supernatants or with supernatants from whole cultures of Y. enterocolitica were similar, suggesting that most of the ST produced by this microorganism in broth cultures is extracellular. The amount of ST produced by Y. enterocolitica, as well as the ambient temperature at which inoculated mice were kept during the assay, was found to influence gut/carcass weight ratios obtained with both tests. Enterotoxigenicity and the temperature at which mice were kept were interrelated, such that for weakly enterotoxigenic strains there were no significant differences among gut/carcass weight ratios for the conventional and modified infant mouse tests carried out at 18 or 25 degrees C, but at 30 degrees C the values in the modified test were higher for most ST preparations with Pai-Mors medium. The influence of ambient temperature was more pronounced at 37 degrees C, since most strains produced negative results in the conventional test at this temperature. We conclude that the conventional infant mouse test is adequate for assaying yersinial ST, provided that the temperature at which mice are kept during the assay is fixed at around 25 degrees C.
Agar microdroplet assay for delayed hypersensitivity to Legionella pneumophila serogroup 1
Authors: Widen R , Klein T , Lee I , Friedman H
Published: January 2020

An agarose microdroplet technique was utilized to assess the cellular immunity of guinea pig lymphoid cells to Legionella pneumophila antigen in vitro. Both direct and indirect migration inhibition procedures were shown to be capable of detecting sensitization of guinea pigs to L. pneumophila antigens. Animals injected with adjuvant alone or unrelated antigens did not yield spleen cells responsive to L. pneumophila, indicating the specificity of the response. Migration inhibition factor induction by Legionella antigen in vitro correlated well with skin test responses in vivo. The positive reaction detected by migration inhibition occurred at times similar to that of skin reactivity but later than that of the earliest serum antibody titers. The assay appears to be useful for monitoring sensitization to Legionella and may be applicable to the study of cell-mediated immunity to this bacterium in infected individuals.
Evaluation of the Anaerobe-Tek system for identification of anaerobic bacteria
Authors: Buesching W J , Svirbely J R , Ayers L W
Published: January 2020

The Anaerobe-Tek system of Flow Laboratories, Inc. (McLean, Va.), is a new bacterial identification system which uses Gram morphology, sporulation, and reactions from 15 agar-based biochemical tests to generate a six-digit code number for identification of anaerobic bacteria. Supplemental tests are recommended when necessary to complete species identification. Individual test and identification performance of this system was evaluated by testing 216 anaerobic bacteria representing 31 species and one Centers for Disease Control unnamed group in parallel with a routine clinical laboratory identification system. Most of the tests in the Anaerobe-Tek system performed well; 85% of the organisms were correctly identified. The 32 (15%) failures in identification were due to omission from the identification code data base (38%), false-negative indole reactions (22%), and other incorrect biochemical reactions (40%). The replacement of the recommended indole test with an extraction method using the inoculum broth and an expansion of the data base of the system could raise the correct identification for this organism population to over 90% with no change in the test materials.
Selective enrichment broth medium for isolation of Campylobacter jejuni
Authors: Martin W T , Patton C M , Morris G K , Potter M E , Puhr N D
Published: January 2020

A new selective Campylobacter enrichment broth for the isolation of Campylobacter jejuni has been tested with fecal specimens of human, poultry, and bovine origin. We compared the isolation rate with that from the simultaneous direct plating of a duplicate specimen. Of the 380 duplicate specimens examined comparatively, we obtained a 46.3% increase in isolation of C. jejuni by using the new Campylobacter enrichment broth medium.
Microbiological and clinical evaluation of the isolator lysis-centrifugation blood culture tube
Authors: Henry N K , McLimans C A , Wright A J , Thompson R L , Wilson W R , Washington J A
Published: January 2020

In a controlled evaluation of 6,010 blood cultures, the yield of clinically significant microorganisms was greater from a lysis-centrifugation system (Isolator, Du Pont Co.) than from a nonvented vacuum bottle containing tryptic soy broth with sodium polyanetholesulfonate and CO2 and a vented bottle containing biphasic brain heart infusion medium with sodium polyanetholesulfonate. The Isolator significantly increased the frequency of isolation of Staphylococcus aureus and Candida spp. and significantly decreased the time required for the detection of S. aureus, Pseudomonas aeruginosa, and Candida spp.; however, anaerobic bacteria were recovered significantly more frequently from nonvented bottles with tryptic soy broth, and pneumococci were recovered significantly more frequently from both bottle systems. Contamination of cultures was significantly greater with the Isolator system than with either bottle system. Regardless of the number of blood cultures obtained per septic episode, the Isolator detected microbiologically proven bacteremia or fungemia in a significantly greater number of patients and significantly decreased the time required for detection.
Concurrent comparability of automated systems and commercially prepared microdilution trays for susceptibility testing
Authors: Hansen S L , Freedy P K
Published: January 2020

Susceptibility test results from 100 clinical isolates, using the AMS, MS-2, Autobac MTS, Micro-Media system, and Sensititre, were compared with results from the proposed National Committee for Clinical Laboratory Standards reference microdilution method for minimum inhibitory concentrations and with Bauer-Kirby results. Isolates were tested concurrently by each method on consecutive days to obtain duplicate results. The data were computer analyzed, using National Committee for Clinical Laboratory Standards guidelines for break point interpretation. Analysis was centered on drug-organism combinations and not on overall percent correlation. Data were analyzed for comparability to the reference methods and for reproducibility within each system. Commercial system results were very reproducible. Results from 4- to 8-h tests (AMS, MS-2, MTS) gave more very major discrepancies when compared with either reference method than did results from 15- to 18-h systems (Micro-Media, Sensititre).
New serogroup of Legionella pneumophila, serogroup 8
Authors: Bissett M L , Lee J O , Lindquist D S
Published: January 2020

A strain of Legionella pneumophila (designated Concord 3) was isolated from a postmortem lung specimen of a patient with pneumonia. Direct fluorescent-antibody and immunoelectrophoresis tests, using absorbed and unabsorbed reagents prepared to this and other strains of legionellae, indicated that the Concord 3 strain represents a new serogroup of L. pneumophila, serogroup 8.
Immunochemical detection of a common antigen among Streptococcus uberis isolates
Authors: Jones K F , Norcross N L
Published: January 2020

Fifty-three isolates of Streptococcus uberis from various sources were examined for the presence of a common antigen. Initially, a serum was produced in rabbits which, by using rocket line immunoelectrophoresis, proved to react with identity to all of the S. uberis crude extracts as well as group B and E streptococcal extracts. The antigen(s) responsible for this cross-reactivity was partially purified by Sephacryl S-200 gel chromatography and analyzed by fused rocket immunoelectrophoresis. Further analysis by immunodiffusion showed that probably two antigens in the gel chromatography-consolidated fractions were common to the S. uberis and group B and E isolates, but that one of the antigens present was unique to S. uberis. Trypsin destroyed the immunoreactivity of this antigen. Isolation of this common antigen could possibly alleviate some of the tedium associated with the identification of this organism.
Location of Campylobacter jejuni in infected chicken livers
Authors: Barot M S , Mosenthal A C , Bokkenheuser V D
Published: January 2020

To determine whether chicken livers infected with Campylobacter jejuni are seeded in vivo or contaminated after slaughtering, 117 livers purchased in retail outlets in New York were examined for surface and tissue infections. Of 56 livers positive for C. jejuni, 36 yielded surface growth only, 18 both surface and tissue growth, and 2 tissue growth only. The scanty growth from tissue samples suggests a carry-over of organisms from the surface. It was concluded, therefore, that contamination is most likely due to unhygienic handling of offal. Infection rates of livers varied from retailer to retailer.
Simple method for preparation of antibody-enzyme conjugates for enzyme-linked immunosorbent assays
Authors: De Jong P J
Published: January 2020

Mixing suspensions of rabbit antibody for staphylococcal enterotoxin A and commercial anti-rabbit immunoglobulin G-alkaline phosphatase conjugate produced a complex conjugate suitable for use as the second antibody in a conventional enzyme-linked immunosorbent assay. The method was useful for detecting 1 ng of staphylococcal enterotoxin A per ml.
Detection of immunoglobulin M antibodies with antigen-tagged latex particles in an immunosorbent assay
Authors: Remington J S , Eimstad W M , Araujo F G
Published: January 2020

A method is described for the detection of immunoglobulin M (IgM) antibodies to Toxoplasma gondii by using latex particles coated with antigens of the organism. An excellent qualitative agreement was noted when the latex method was compared with other tests for the detection of IgM toxoplasma antibodies. The method is simple and inexpensive to perform and does not require the use of whole killed organisms or an enzyme conjugate.
Detection of Rift Valley fever virus antigen by enzyme-linked immunosorbent assay
Authors: Niklasson B , Grandien M , Peters C J , Gargan T P
Published: January 2020

A double-antibody (sandwich) enzyme-linked immunosorbent assay (ELISA) was adapted to detect Rift Valley fever virus antigen. Antibodies were purified from hyperimmune mouse and rabbit sera by affinity chromatography, using CNBr-activated Sepharose 4B coupled to a beta-propiolactone-inactivated sucrose-acetone-extracted suckling mouse liver antigen. In the assay, antigen was captured by mouse antibody adsorbed to polystyrene plates and then detected by reacting sequentially with rabbit anti-Rift Valley fever virus antibody and swine anti-rabbit immunoglobulin G conjugated to alkaline phosphatase. ELISA proved to be useful in measuring viral antigen in different animal systems. However, great variation was found in the amount of antigen per PFU encountered in different circumstances. The ELISA system was optimized using supernatant fluids from infected Vero cell cultures and had a sensitivity of 10(5) PFU/ml. Hamsters develop progressive viremia, much as seen in susceptible domestic animals, such as lambs; ELISA could reliably detect 10(6) PFU/ml of viremic hamster serum. Rhesus monkeys with Rift Valley fever infection were positive by ELISA even when viremias were only 5 X 10(3) PFU/ml. ELISA also proved to be useful in measuring viral antigen in infected mosquitoes.
New selective plating medium for isolation of Vibrio vulnificus biogroup 1
Authors: Brayton P R , West P A , Russek E , Colwell R R
Published: January 2020

A new plating medium (VV agar) has been developed as an alternative to thiosulfate-citrate-bile salts-sucrose (TCBS) agar for the isolation of Vibrio vulnificus. Salicin (2% wt/vol) is employed as the source of carbohydrate, with potassium tellurite (0.0005% wt/vol), crystal violet (0.00015% wt/vol), oxgall (0.8% wt/vol), and a pH of 8.6 to inhibit growth of gram-positive and gram-negative organisms other than V. vulnificus. Because strains of V. vulnificus do not strongly ferment salicin in VV agar, a pH indicator has not been included in the medium. Growth of V. vulnificus appears on VV agar as large grey colonies with black centers. Other non-Vibrio strains which grow on the medium produce smaller colonies and fail to take up tellurite. VV agar has proved to be more effective than TCBS agar in inhibiting members of the Enterobacteriaceae as well as gram-positive cocci. Only Vibrio strains capable of utilizing salicin grow well on VV agar. Recovery and growth of V. vulnificus are superior on VV agar, compared with TCBS agar.
4-h Identification of Pseudomonas aeruginosa with 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan
Authors: Davis J R , Stager C E , Araj G F
Published: January 2020

A total of 361 gram-negative bacilli were evaluated for their ability to grow in the presence of 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan. The minimum time required for the production of visual turbidity in brain heart infusion broth was determined to be 4 h in shake cultures at 35 degrees C. The minimal inhibitory concentration (MIC) of 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan in brain heart infusion broth was determined for 174 isolates. The MICs for all 40 Pseudomonas aeruginosa isolates tested were greater than 50 micrograms/ml. The MICs for the other 53 pseudomonads tested were less than or equal to 5 micrograms/ml. Among 81 other gram-negative bacilli tested, the MICs for 4 were 15 micrograms/ml, the MICs for 15 were 10 micrograms/ml, the MICs for 21 were 5 micrograms/ml, and the MICs for 41 were less than or equal to 1 micrograms/ml. Based on these data, 361 gram-negative bacilli were inoculated into brain heart infusion broth containing 15 micrograms of 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan per ml and incubated on a shaker for 4 h. The only bacteria that produced visual turbidity were identified as P. aeruginosa (170 of 170 isolates).
Detection of mycobacteria by radiometric and standard plate procedures
Authors: Damato J J , Collins M T , Rothlauf M V , McClatchy J K
Published: January 2020

A group of 89 smear-positive sputum specimens were evaluated by radiometric and standard plate procedures to determine the methodology which would provide the earliest detection of mycobacteria and maximum test sensitivity. Digested non-decontaminated specimens were concentrated and inoculated into modified selective BACTEC radiometric 7H12 broth and Mitchison selective 7H10 agar. Sodium hydroxide (1.5% final concentration) was then used to decontaminate these specimens. They were then concentrated and inoculated into both selective and nonselective 7H12 radiometric broths and into selective 7H10 and nonselective Middlebrook 7H11 agar media. The specimen processing and media combinations providing the earliest detection were non-decontaminated specimens with modified selective 7H12 BACTEC broth and decontaminated specimens with 7H12 BACTEC broths. Maximum sensitivity (percent positive) was obtained by using non-decontaminated specimens on Mitchison selective 7H10 Agar (98%) or decontaminated specimens in 7H12 BACTEC broth (95%). The decontamination process was found to reduce significantly the number of mycobacteria in clinical specimens, particularly the mycobacteria other than Mycobacterium tuberculosis. The specimen processing-media combinations providing the earliest detection and maximum recovery of mycobacteria (100%) were non-decontaminated specimens with modified selective 7H12 BACTEC broth or Mitchison selective agar and decontaminated specimens with 7H12 BACTEC broth or 7H11 agar.
Viral antibody screening system that uses a standardized single dilution immunoglobulin G enzyme immunoassay with multiple antigens
Authors: Blomberg J , Nilsson I , Andersson M
Published: January 2020

We present an enzyme-linked immunosorbent assay (ELISA) system for the simultaneous determination of immunoglobulin G antibodies directed against several viruses. Antibodies to up to eight different viruses could be determined for three different sera on one microtitration plate. After subtraction of the absorbance values obtained with the control antigens, the viral antigen absorbancies were expressed as percentages of the absorbance obtained with a pooled immunoglobulin standard. This value, the relative antibody activity, was rapidly calculated by means of a computer directly connected to the ELISA photometer and was stored on magnetic disks, thereby facilitating seroepidemiological studies. The reproducibility of the relative antibody activity was calculated to at best +/- 3.6% (standard deviation) in an intraassay test and to at worst +/- 20.4% (standard deviation) in an interassay test. Each serum was analyzed only at a dilution of 1/75. The sensitivity of this single-dilution ELISA (SD-ELISA) method for the detection of titer rises was compared with those of conventional methods, mostly complement fixation but also hemagglutination inhibition. A total of 142 of 155 (92%) paired sera showing fourfold complement fixation or hemagglutination inhibition rises also showed significant results in SD-ELISA. A total of 22 of 57 (39%) significant relative antibody activity rises were significant in complement fixation or hemagglutination inhibition. Overall, up to twice as many significant titer rises could be detected with SD-ELISA. Most of these seemed to have a sound correlation with clinical data. The specificity of SD-ELISA was found to be similar to that of complement fixation, with some cross-reactions occurring between herpes simplex and varicella-zoster virus antigens and between parainfluenza viruses. We have found SD-ELISA to be a valuable clinical virological tool that supplements conventional serology.
Evaluation of intestinal parasite morphology in polyvinyl alcohol preservative: comparison of copper sulfate and mercuric chloride bases for use in Schaudinn fixative
Authors: Garcia L S , Shimizu R Y , Brewer T C , Bruckner D A
Published: January 2020

As a result of disposal problems inherent in the use of mercury compounds, many laboratories have considered using copper sulfate as a substitute for mercuric chloride in polyvinyl alcohol (PVA) preservative. The primary use for PVA-preserved specimens is the permanent stained smear, the most important technique for the identification of intestinal protozoa. A comparison of organism recovery and morphology was undertaken with PVA containing either copper sulfate or mercuric chloride base. Paired fecal specimens (417 pairs) were collected and examined with the Formalin-ether concentration and Trichrome stain techniques. Numbers of organisms recovered and helminth egg and protozoan morphology were assessed from the concentration sediment. Morphology, clarity of nuclear and cytoplasmic detail, overall color differences, and the ease or difficulty in detecting organisms in fecal debris were assessed from the permanent stained smear. No significant differences were found in the numbers and morphology of organisms seen in the concentration sediment. However, when the trichrome stain was used, the overall morphology of the intestinal protozoa preserved in PVA with copper sulfate was not equal to that seen with PVA with mercuric chloride. We do not recommend switching from mercuric chloride base to copper sulfate base unless that is the only option available for the preparation of permanent stained smears.
Rapid inoculum standardization system: a novel device for standardization of inocula in antimicrobial susceptibility testing
Authors: Wicks J H , Nelson R L , Krejcarek G E
Published: January 2020

A rapid inoculum standardization system for antimicrobial susceptibility testing without incubation or the conventional turbidity adjustment has been developed. The rapid inoculum standardization system consists of a plastic rod with cross-hatched grooves on one end and a specific nutrient medium in a vial. The crosshatched grooves are designed to pick up and release a known number of viable microorganisms. In use, the end of the rod is touched to five colonies 1 to 2 mm in diameter from a primary agar plate, thus filling the grooves with bacteria. The rod is placed into the vial, and the bacteria are suspended in the medium by agitation with a Vortex Genie Mixer. The resulting suspension contains 5 X 10(7) to 5 X 10(8) CFU/ml for most gram-negative bacilli and gram-positive cocci. Microorganisms such as streptococci that have colonies less than 1 mm in diameter require as many as 10 colonies for an adequate inoculum suspension. Ninety-five commonly encountered bacterial isolates were tested in triplicate by agar plate counts. The resulting overall geometric mean of the agar plate counts was 1.52 X 10(8) CFU/ml for the species tested. We have found that the rapid inoculum standardization system provides a consistent and reproducible method for the standardization of inoculum for antimicrobial susceptibility testing without the incubation period and turbidity adjustment.
Detection of group B streptococcal antigens in amniotic fluid of rhesus monkeys
Authors: Hemming V G , London W T , Smith L P , Curfman B L , Fischer G W , Sever J L
Published: January 2020

To simulate group B streptococci (GBS) amniotic fluid infections common in humans and to examine bacterial growth and the appearance of GBS antigens in vivo, GBS were injected into the amniotic cavity of 19 near-term rhesus monkeys. Transabdominal aspirates of amniotic fluid were obtained before bacterial challenge, after 2 and 6 h, and during cesarean section delivery (24 h). Each fluid was quantitatively cultured for GBS. Specimens of amniotic fluid and gastric aspirate from each infant were tested for the presence of GBS antigens with a commercial latex particle agglutination test (Wellcogen Strep B; Wellcome Diagnostics, Dartford, England). To eliminate nonspecific latex particle agglutination reactivity, presumably caused by proteins, a processing procedure was required. Despite active proliferation of bacteria, only 12% of the 2-h amniotic specimens were latex particle agglutination positive. In contrast, 94% of th3 6-h and 100% of the 24-h specimens had detectable antigens, as did 89% of the gastric fluid specimens aspirated from the 19 newborns. Latex particle agglutination tests, after proper processing, will readily detect GBS antigens in amniotic or gastric aspirate fluid from experimentally infected rhesus monkeys.
Electrophoretic characterization of soluble protein extracts of Legionella pneumophila and other members of the family Legionellaceae
Authors: Lema M , Brown A
Published: January 2020

The soluble peptides of strains of Legionella pneumophila, Tatlockia micdadei, Fluoribacter bozemanae, Fluoribacter dumoffii, and Fluoribacter gormanii were studied by polyacrylamide gel electrophoresis. Characteristic patterns were seen for Legionella and Tatlockia strains, whereas the patterns for the Fluoribacter strains were variable as would be expected for this genetically heterogeneous group. Grouping by peptide pattern was consistent with proposed taxons based on DNA-DNA homology. By using a new silver stain technique, the sensitivity and ease of pattern recognition were enhanced significantly. This technique is an easily applied general method for distinguishing between strains in epidemiological studies.
Bacteriophage and bacteriocin typing scheme for Clostridium difficile
Authors: Sell T L , Schaberg D R , Fekety F R
Published: January 2020

The study of the epidemiology of infection with Clostridium difficile would be aided by a way to type individual bacterial isolates. We therefore sought bacteriophages for use in typing. With mitomycin C exposure (3 micrograms/ml), filtrates from 10 strains of C. difficile had plaque-forming lytic activity on other C. difficile strains. Individual phage were passaged and made into high-titer stock preparations for typing. Electron microscopy revealed tailed phage particles from one such preparation. In addition to phage, inhibitory activity without distinct plaque formation consistent with bacteriocins was observed for 20 strains. C. difficile isolates from 16 patients taken 1 to 14 days apart were similar in their phage sensitivity pattern, whereas isolates from separate geographic locations showed a great variety of patterns. We conclude that bacteriophage should be useful for typing strains of C. difficile.
Comparison of the antibacterial spectra of cephalexin and cefaclor with those of cephalothin and newer cephalosporins: reevaluation of the class representative concept of susceptibility testing
Authors: Preston D A , Jones R N , Barry A L , Thornsberry C
Published: January 2020

The validity of the class representative concept for in vitro susceptibility testing of older cephalosporins was reevaluated. Two oral cephalosporins, cephalexin and cefaclor, were compared with the established cephalosporin class representative, cephalothin, by using reference microdilution minimal inhibitory concentrations of 528 isolates of a wide variety of gram-positive and gram-negative bacterial pathogens. For each comparison, there were only 15 (2.8%) random major and very major interpretive discrepancies. Additional comparisons confirmed the need to test second-generation (cefamandole) and third-generation (cefotaxime) cephalosporins separately. These results provide reasonable assurance that the use of cephalothin as an in vitro predictor of qualitative bacterial susceptibility to these two oral cephalosporins remains an acceptable alternative to testing each antibiotic individually.
Temperature-related variations in the lipid composition of methicillin-resistant and methicillin-susceptible Staphylococcus aureus strains
Authors: Pisano M A , Ball D J , Eriquez L
Published: January 2020

Growth of methicillin-susceptible and -resistant strains of Staphylococcus aureus at 28 and 37 degrees C led to changes in the relative amounts of phospholipids recovered. The major phospholipids present in these strains were phosphatidylglycerol, lysophosphatidylglycerol, and diphosphatidylglycerol. Phosphatidylglycerol tended to occur in lower amounts in the resistant strains, but it was the major phospholipid in both methicillin-susceptible and -resistant S. aureus strains. Growth patterns and total lipid concentrations were similar in all strains.
Advantages of BACTEC hypertonic culture medium for detection of Haemophilus influenzae bacteremia in children
Authors: La Scolea L J , Sullivan T D , Dryja D , Neter E
Published: January 2020

The hypertonic and aerobic culture media in the BACTEC system were compared for the detection of Haemophilus influenzae bacteremia in children. Of 1,611 blood cultures, 30 were positive for this pathogen. The aerobic and hypertonic media gave positive results in 28 and 29 cultures, respectively. Within the first 12 h, H. influenzae was detected in the hypertonic medium in 48.5% of the positive cultures as compared to 35% for the aerobic medium. Importantly, after the first 12 h, the hypertonic medium yielded positive results sooner than did the aerobic medium, the difference being statistically significant (P less than 0.01). The hypertonic medium yielded positive results earlier than the aerobic medium in nine cultures; the reverse was seen in only one culture. Furthermore, the aerobic medium gave negative growth index readings despite growth, as shown by microscopy and subculture, in 43% of the total cultures in contrast to only 13% for the hypertonic medium, a significant difference (P less than 0.05). Thus, the present study indicates a distinct advantage of hypertonic medium compared with aerobic medium in the automated BACTEC system for earlier detection of H. influenzae bacteremia and is recommended for those age groups in which this pathogen plays a predominant role.
Micro-Media Systems anaerobe panel versus broth disk method in anaerobe antimicrobial testing
Authors: Polomski J C , Bauer S H , McClatchey K D
Published: January 2020

Frozen microtitration trays manufactured by Micro-Media Systems (MMS) for antimicrobial testing of anaerobic bacteria were evaluated and compared with the broth disk elution method of Virginia Polytechnic Institute (VPI) described by Wilkins and Thiel. A total of 224 clinical anaerobic isolates were tested. Susceptibility results were compared for carbenicillin, cefoxitin, chloramphenicol, clindamycin, penicillin, and tetracycline. Published procedures for the MMS and VPI methods were followed using aerobic inoculation. Growth performance in the MMS method was 74% compared with 89% in the VPI method. For each antibiotic, the MMS minimum inhibitory concentration was compared with the VPI test concentration. Of the 972 drug-organism combinations, 2.9% of the results were discrepant. Clindamycin and tetracycline accounted for 82% of the discrepancies. The MMS anaerobe susceptibility panels were easy to inoculate and interpret and compared well with the VPI broth disk susceptibility method.
Demonstration of intraocular synthesis of immunoglobulin G toxoplasma antibodies for specific diagnosis of toxoplasmic chorioretinitis by enzyme immunoassay
Authors: Turunen H J , Leinikki P O , Saari K M
Published: January 2020

By using a modified enzyme immunoassay we have conducted a detailed study on the intraocular synthesis of toxoplasma antibodies during ocular toxoplasmosis. In control patients operated on for cataracts, the ratio of immunoglobulin G (IgG) toxoplasma antibodies in serum to those in aqueous humor was more than 100. In eight of the nine patients with clinically diagnosed toxoplasmic chorioretinitis, the ratio ranged between 6 and 56. In five patients with some other type of uveitis, the ratio was comparable with that in controls. Parallel determinations of mumps IgG antibody ratios were carried out to prove that the increased intraocular toxoplasma antibody levels were not a result of increased diffusion or polyclonal antibody stimulation. In all patients, mumps antibody ratios were within normal range. We also tested the samples of aqueous humor for IgM and IgA antibodies, but the antibodies in the aqueous humor were found to be exclusively IgG. Our results indicate that IgG-class anti-toxoplasma antibodies are produced locally within the eye in cases of toxoplasmic chorioretinitis. The determination of these antibodies can offer a valuable aid to make a specific etiological diagnosis of ocular toxoplasmosis.
Lyophilized microculture susceptibility test for ketoconazole, miconazole, clotrimazole, and griseofulvin against dermatophytes
Authors: Granade T C , Mothershead M A , Artis W M
Published: January 2020

A lyophilized microculture antimycotic susceptibility testing system for ketoconazole, miconazole, griseofulvin, and clotrimazole is described. Microculture plates were loaded with 100 microliters of medium and 10 microliters of appropriate concentrations of the four antimycotics and were lyophilized to complete dryness. The lyophilized plates were stored at -70 degrees C or 4 degrees C or in a desiccator at 25 degrees C. Samples from each storage condition were rehydrated at 1, 2, 3, 4, 5, 6, 8, 10, and 12 months and inoculated with Trichophyton mentagrophytes (Robin) Blanchard ATCC 18748. All of the minimal inhibitory concentrations (MICs) generated from the lyophilized microcultures were within one experimental dilution of MICs derived from fresh microcultures. The ability of reconstituted lyophilized microcultures to consistently produce MICs comparable to MICs derived from fresh microcultures was characterized. Nine dermatophyte isolates were tested five times each over a 70-day period. The MICs derived were reproducible and comparable to MICs determined by freshly prepared microculture tests. Lyophilization of freshly prepared antimycotic-containing microcultures does not alter the MIC resolution of the testing system and provides an effective method of storage of prepared antimycotic tests for ketoconazole, miconazole, clotrimazole, and griseofulvin.
Gonococcal sensitivity to fecal lipids can be mediated by an Mtr-independent mechanism
Authors: McFarland L , Mietzner T A , Knapp J S , Sandstrom E , Holmes K K , Morse S A
Published: January 2020

Various factors affect the sensitivity of Neisseria gonorrhoeae to physiological levels of hydrophobic molecules. A total of 98 N. gonorrhoeae strains from rectal, cervical, and urethral cultures of homosexual men and heterosexual men and women were examined for their sensitivities to fecal lipids. Isolates were characterized according to cell envelope phenotype, auxotype, and protein I serogroup. Although cell envelope phenotype was an important factor in the resistance of this organism to fecal lipids (Mtr phenotype greater than wild type greater than Env phenotype), other factors were also of importance. AHU- strains (strains having a requirement for arginine, hypoxanthine, and uracil) uniformly exhibited a wild-type envelope phenotype but were as sensitive to fecal lipids as were Env strains. The protein I serogroup was not a factor in determining the sensitivity of wild-type envelope phenotype non-AHU- strains to fecal lipids. However, sexual preference and site of isolation were important factors. Wild-type envelope phenotype (non-AHU-) strains from homosexual men and heterosexual women were more resistant to fecal lipids than were similar isolates from heterosexual men. When these strains were compared by isolation site, it was observed that rectal isolates from homosexual men and heterosexual women were more resistant than were cervical isolates from heterosexual women or urethral isolates from heterosexual men. Urethral isolates from homosexual men were also more resistant to fecal lipids than were urethral isolates from heterosexual men. These data suggest that the host environment can select for increased resistance to hydrophobic molecules by an Mtr-independent mechanism. The basis for this Mtr-independent resistance is presently unknown, but it is likely that it involves an alteration of the target site(s) for fecal lipid inhibition.
Evaluation of the updated MS-2 Bacterial Identification system in comparison with the API 20E system
Authors: DiPersio J R , Dyke J W , Vannest R D
Published: January 2020

The recently updated MS-2 Bacterial Identification system software (Abbott Laboratories, Diagnostic Division, Irving, Tex.) was compared with the original MS-2 Bacterial Identification software and the API 20E, using 968 strains of Enterobacteriaceae. The updated MS-2 software correctly identified 94.4% of the isolates tested. API 20E and the original MS-2 software correctly identified 91 and 85.3% of the strains, respectively. MS-2 responses were considered to be equivocal (needing additional tests for verification) if the percent likelihood values were less than 80%. The percentage of equivocal responses was reduced from 6.5% with the original software to 2.2% with the updated software, and the percentage of incorrect identifications was reduced from 8.2 to 3.4% with the original and updated software, respectively. Organisms belonging to 25 taxonomic groups were tested. Direct comparison of the two MS-2 programs showed that the updated MS-2 software increased the identification accuracy of Salmonella spp., Enterobacter cloacae, Providencia stuartii, Escherichia coli, Shigella spp., Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, and Acinetobacter calcoaceticus. A decrease in accuracy was seen with Citrobacter freundii, Hafnia alvei, Enterobacter agglomerans, and Yersinia pseudotuberculosis when the updated software was used. The remaining 12 taxonomic groups were not affected by the software changes. The updated MS-2 software appears to significantly improve the identification accuracy of the MS-2 Bacterial Identification system.
Rapid method for identification and susceptibility testing of Escherichia coli bacteriuria
Authors: Dennstedt F E , Stager C E , Davis J R
Published: January 2020

This report describes a rapid method for the identification and susceptibility testing of Escherichia coli bacteriuria by use of the Autobac urine screen (AUS), a 5-h indole test, and the AutoMicrobic system E. coli Susceptibility Card (AMS-ECSC). All specimens that were AUS negative at 3 and 5 h were reported as negative. All specimens that were AUS positive at 3 or 5 h were removed from the refrigerator and streaked to a MacConkey-blood agar biplate with a 0.001-ml calibrated loop and incubated at 35 degrees C. The standard method for identification and susceptibility testing consisted of inoculating isolated colonies into the AutoMicrobic system Enterobacteriaceae-Plus Biochemical Card and the AutoMicrobic system General Susceptibility Card. Of 915 specimens, 212 (23.2%) were AUS positive at 3 h, of which 112 (52.8%) were indole positive when tryptophan broth was tested at 5 h. The sensitivity and specificity of this screening method for E. coli bacteriuria were 78.8 and 72.2%, respectively. If contaminated cultures were excluded, specificity was 94.4%. When the indole test was positive, 10 microliters of growth from tryptophan broth was used as inoculum for the AMS-ECSC. AMS-ECSC results were final at 12 h. The sensitivity and specificity of the AMS-ECSC for identification of E. coli were 90.4 and 55.0%, respectively. If contaminated cultures were excluded, specificity was 100%. AMS-ECSC susceptibility results demonstrated an overall agreement of 94.3% with the standard method, with 0.5% very major, 3.4% major, and 1.8% minor discrepancies. The biplate was examined after overnight incubation, and when colonies compatible in morphology with E. coli were present in significant numbers, AMS-ECSC results were reported. When discrepancies were found between biplate and AMS-ECSC results, the biplate was processed in the conventional manner. A rapid method for identifying and performing susceptibility tests for approximately 70% of the specimens with E. coli bacteriuria is described.
Radioimmunoassay and opsonic antibody responses to pneumococcal capsular polysaccharide vaccine in serum and ascitic fluid of cirrhotic patients
Authors: Simberkoff M S , Schiffman G S , Spicehandler J R , Moldover N H , Rahal J J
Published: January 2020

Pneumococcal capsular polysaccharide vaccine was administered to 19 cirrhotic patients and to 25 control subjects. Radioimmunoassay antibody concentration and opsonic titers (OT) were measured in sera and ascites collected before and 3 to 4 weeks after inoculation. The geometric mean antibody concentrations in prevaccination sera from the cirrhotic patients were significantly increased to types 3, 4, 7F, 8, 9N, and 12F antigens, and in postinoculation sera their geometric mean antibody concentration was increased to types 3, 9N, and 12F antigens. OT to Streptococcus pneumoniae type 3 correlated with the radioimmunoassay antibody concentration in postinoculation sera. Of 14 cirrhotic subjects, 3 had OT of greater than or equal to 4 in prevaccination sera, and the highest OT and radioimmunoassay antibody concentration were observed in postinoculation specimens from this group. Antibody and OT against S. pneumoniae type 3 were also observed in ascitic specimens. These data suggest that cirrhotic subjects respond to pneumococcal capsular polysaccharide with antibodies in both serum and ascitic fluid. However, the protective efficacy of this antibody response must be assessed by larger prospective studies.
A three-year study of nosocomial infections associated with Pseudomonas aeruginosa
Authors: Sherertz R J , Sarubbi F A
Published: January 2020

During a 3-year study period in a university teaching hospital, 417 nosocomial infections associated with Pseudomonas aeruginosa were documented in 321 patients. The overall rate of P. aeruginosa nosocomial infection was 5.3 cases per 1,000 patients. Residence on the surgery or medicine service, advanced patient age, and exposure to the burn, surgery, or medicine intensive care units correlated with higher rates of infection. The most common sites for P. aeruginosa infection were the lower respiratory tract, urinary tract, blood stream, and surgical wounds. Nosocomial P. aeruginosa lower respiratory tract and blood stream infections were significantly associated with exposure to certain intensive care units, whereas P. aeruginosa urinary tract infections more commonly occurred on the neurology and neurosurgery services. Results of live antigen serotyping showed that serotype 6 was most common, followed by serotypes 1 and 11. Serotype 6 correlated with resistance to carbenicillin, gentamicin, and tobramycin, and serotype 11 correlated with resistance to carbenicillin. Two-thirds of the isolates tested were sensitive to carbenicillin, gentamicin, and tobramycin, but 13.2% were resistant to all three of these drugs. P. aeruginosa isolates resistant to all three drugs were associated with urinary tract infections.
Demonstration of serum antibodies to Cryptosporidium sp. in normal and immunodeficient humans with confirmed infections
Authors: Campbell P N , Current W L
Published: January 2020

Antibodies to Cryptosporidium sp. were detected in sera from 12 immunocompetent individuals recovered from cryptosporidiosis and from 5 subjects with an acquired immunodeficiency syndrome and persistent cryptosporidiosis by an indirect immunofluorescent (IIF) test. Marked seroconversion accompanied recovery from infection in immunocompetent individuals, and their IIF titers remained high (1:40 to 1:640) for at least 1 year. No antibodies to Cryptosporidium sp. were detected in sera from two subjects with hypogammaglobulinemia, normal T-cell function, and persistent cryptosporidiosis or in sera from individuals not previously exposed to Cryptosporidium sp. Very little or no cross-reactivity with the other coccidia--Toxoplasma, Sarcocystis, and Isospora spp.--occurred in the IIF test procedure. The application of this IIF procedure, along with recently developed techniques to detect oocysts in the feces, should provide the basis for a more accurate assessment of the number of individuals within any subject group with previous and active Cryptosporidium infections.
Susceptibility testing of multidrug-resistant Staphylococcus aureus with the Sceptor microdilution system
Authors: Blair H C , Cleary T J
Published: January 2020

The antimicrobial susceptibilities of Staphylococcus aureus isolates were concurrently determined by the Sceptor system (BBL Microbiology Systems, Cockeysville, Md.) and by the standard disk diffusion method. For the methicillin-resistant isolates, there was greater than 98% agreement between the two test results with penicillin G, erythromycin, clindamycin, tetracycline, gentamicin, and tobramycin. Major disagreements (susceptible by one method and resistant by the other) were 7% for methicillin, 13.5% for cephalothin, 3.5% for cefamandole, and 27% for amikacin. The major discrepancies for methicillin were eliminated by supplementing the inoculum broth with salt. For methicillin-susceptible isolates, agreement between the two methods was 96 to 100% for all antibiotics except amikacin.
Evaluation of trichophyton agars for identification of Trichophyton soudanense
Authors: Weitzman I , Salkin I F , Rosenthal S A
Published: January 2020

Studies of three monoconidial subcultures of each of 10 isolates of Trichophyton soudanense on seven trichophyton agars revealed variations in growth among the subcultures of each isolate and among the isolates themselves on six agars. In contrast, greater consistency and generally good to excellent growth were noted with all isolates on trichophyton agar 1 (basal medium). These results are contrary to those found with other Trichophyton species and suggest that growth on the trichophyton agars is not a suitable test for the identification of T. soudanense.
Enhanced detection of polymicrobic bacteremia by repeat subculture of previously positive blood cultures
Authors: Hansen S L , Hetmanski J
Published: January 2020

Blood subcultures repeated 3 days after the cultures were first identified as positives increased our detection of polymicrobic bacteremia in 9.1 to 27% of clinically significant patient episodes. Reincubation and repeated subculture of previously positive blood cultures had a direct impact on the therapeutic management of patients with polymicrobic bacteremia.
Comparison of Cultureset to a Conventional Tissue Culture—Fluorescent-Antibody Technique for Isolation and Identification of Herpes Simplex Virus
Authors: Fayram Sandra L. , Aarnaes Sandra , de la Maza Luis M.
Published: January 2020

The isolation and identification of herpes simplex virus types 1 and 2 from clinical specimens with a 48-h system was compared with a conventional tissue culture detection method.
Isolation of Salmonella enteritidis, serotype Horsham, from three American Indian Tribes
Authors: Castle S P , Nims L J , Lapham S C
Published: January 2020

Salmonella enteritidis, serotype Horsham, identified rarely worldwide, was isolated from the stools of six American Indians with gastroenteritis. The patients were from separate tribes located in three geographically distinct villages. Although significant contact was demonstrated between ill individuals within two tribes, no common source for the organism has been identified.