bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsatisfactory specificities and sensitivities of six enzyme immunoassays for antibodies to hepatitis B core antigen
Authors: Caspari G , Beyer H J , Elbert G , Koerner K , Muss P , Schunter F W , Uy A , Gerlich W , Thomssen R , Schmitt H
Published: January 2020

To examine the consistency and comparability of anti-hepatitis B core antigen (anti-HBcAg) assays, four blood donation centers of the Red Cross in the Federal Republic of Germany tested 4,080 unselected blood donors with six different tests in parallel. Confirmation testing of reactive samples was done in the National Reference Center for Viral Hepatitis. Depending on the test kit used, 4.1 to 9.9% of serum samples were initially positive and 2.9 to 7.5% were repeatedly positive. Sixteen percent of serum samples were positive in at least one test but only three percent were positive in all six tests. Statistical analysis of frequency distribution of optical densities for each test suggested that there should be a correction of the cutoff values. This reduced the number of false-positive results by half, but a significant proportion of discrepant results could not be resolved. The lack of specificity and consistency requires cautious interpretation of isolated anti-HBcAg results in clinical specimens. Screening of predominantly anti-HBcAg-negative populations (e.g., blood donors) by the current anti-HBcAg test kits will almost necessarily give unsatisfactory results.
Dot enzyme immunoassay for visual detection of peste-des-petits-ruminants virus antigen from infected caprine tissues
Authors: Obi T U , Ojeh C K
Published: January 2020

An enzyme-linked immunosorbent microassay using nitrocellulose paper as the solid-phase support was developed for the detection of peste-des-petits-ruminants virus antigens in infected caprine tissue homogenates. Dots of tissue homogenates were applied to nitrocellulose papers, and any unreacted sites were blocked with 5% skim milk powder in triethanolamine-buffered saline. After incubation of the papers in tissue culture supernatant monoclonal antibody against the peste-des-petits-ruminants virus, the antigen-antibody reaction was detected with peroxidase-conjugated anti-mouse immunoglobulin G and the enzyme substrate 4-chloro-1-naphthol. Positive results were visualized as blue dots. Results of the dot enzyme immunoassay compared favorably with those of the standard enzyme-linked immunosorbent assay. Incorporation of Nonidet P-40 in the washing solution did not improve the sensitivity of the dot enzyme immunoassay, and pretreatment of homogenates with Nonidet P-40 before application to the nitrocellulose paper inhibited the binding of the antigen to the paper and reduced the intensity of the color development.
Pleural infection caused by Legionella anisa
Authors: Bornstein N , Mercatello A , Marmet D , Surgot M , Deveaux Y , Fleurette J
Published: January 2020

The first case of infection caused by Legionella anisa with isolation of the organism is reported here. The presence of L. anisa in the water supply of the hospital and the isolation of this species in the pleural fluid of a patient suffering from nosocomial pleurisy confirm the potential pathogenicity of this Legionella species.
Significance of specific immunoglobulin M in the chronological diagnosis of 38 cases of toxoplasmic lymphadenopathy
Authors: Del Bono V , Canessa A , Bruzzi P , Fiorelli M A , Terragna A
Published: January 2020

The persistence of immunoglobulin M (IgM) antibody to Toxoplasma gondii in sera from 38 patients after toxoplasmic lymphadenopathy was investigated by using an indirect immunofluorescence assay, a double-sandwich enzyme-linked immunosorbent assay, and an immunosorbent agglutination assay. Positive predictive values at 3 and 6 months after lymphadenopathy were, respectively, 45 and 73% for the indirect immunofluorescence assay, 25 and 45% for the double-sandwich enzyme-linked immunosorbent assay, and 22 and 43% for the immunosorbent agglutination assay.
Detection of asymptomatic initial herpes simplex virus (HSV) infections in animals immunized with subunit HSV glycoprotein vaccines
Authors: Bernstein D I , Ashley R L , Stanberry L R , Myers M G
Published: January 2020

The evaluation of herpes simplex virus (HSV) vaccine efficacy will require methods to detect asymptomatic acquisition of HSV infection and to assess the risk of recurrences in these patients. HSV-infected vaccinees should develop antibodies to HSV polypeptides not included in subunit vaccines. Sera from 57 HSV glycoprotein-vaccinated guinea pigs that had asymptomatic initial infections after genital HSV type 2 challenge were collected after vaccination but before HSV challenge and again 30 days after HSV challenge to determine the antibody response to HSV polypeptides. Antibodies to nonvaccine HSV polypeptides were detected in sera collected after viral challenge from 32 (56%) of these 57 animals. Twenty-six (81%) of the 32 animals with detectable antibody developed recurrent disease; however, recurrences also developed in 11 (44%) of the remaining 25 that did not show detectable antibody to nonvaccine HSV polypeptides. The magnitude of vaginal viral shedding during the initial disease period following challenge was significantly lower in animals that did not develop antibody to nonvaccine polypeptides compared with those that did develop antibody (area under the viral shedding curve, 5.2 +/- 3.2 versus 18.1 +/- 5.8; P less than 0.0001) . These data suggest that detection of antibody to nonvaccine HSV polypeptides will identify the majority (70%) of initially asymptomatic vaccinees that develop recurrent disease but that latency can be established even with markedly reduced levels of viral replication that did not induce a detectable antibody response.
Synthetic peptide homologous to the envelope proteins of retroviruses shares a cross-reacting epitope with the CD4 receptor
Authors: Rothmann J , Hassan N F , Campbell D E , Kamani N , Douglas S D
Published: January 2020

A synthetic peptide (CKS-17) homologous to a highly conserved region of the retroviral transmembrane protein p15E was tested for its effect on receptor expression on monocytes. The CKS-17 amino acid sequence is present in several retroviruses including human T-cell lymphotropic virus types I and II and human immunodeficiency virus. The CKS-17 peptide has been previously shown to inhibit monocyte superoxide production, natural killer cell activity, polyclonal B-cell activation, and monocyte-mediated killing by inactivation of interleukin-1. In this study, we demonstrated that the anti-CD4 monoclonal antibody OKT4 binds strongly in vitro to CKS-17-treated human blood monocytes, whereas other antibodies tested were not reactive. This observed binding was the result of direct interaction of OKT4 antibody with the CKS-17 peptide. Moreover, a partial homology was found in amino acid sequence analysis of the CD4 epitope and the CKS-17 peptide.
Characterization of a Legionella anisa strain isolated from a patient with pneumonia
Authors: Thacker W L , Benson R F , Hawes L , Mayberry W R , Brenner D J
Published: January 2020

Legionella anisa, previously found only in environmental specimens, was isolated from a bronchial lavage specimen of an immunocompromised patient with pneumonia. Growth, physiologic, gas-liquid chromatographic, serologic, and DNA characteristics were consistent with those of the type strain of L. anisa, WA-316-C3 (ATCC 35292).
Evaluation of Bacto TB hydrolysis reagent (Tween 80) for the identification of Branhamella catarrhalis
Authors: Weiner M , Penha P D
Published: January 2020

An investigation of the hydrolysis of Tween 80 reagent by Branhamella catarrhalis and related organisms (Neisseria and Moraxella species) revealed that only B. catarrhalis gave a positive result. A total of 226 strains, including reference organisms and clinical isolates, were studied. B. catarrhalis changed the color of the reagent from amber to pink-red after overnight incubation. We recommend this simple and cost-effective test as an alternative procedure to DNase testing or tributyrin hydrolysis or as a supplemental procedure for the identification of B. catarrhalis in clinical specimens.
Endocarditis associated with Comamonas acidovorans
Authors: Horowitz H , Gilroy S , Feinstein S , Gilardi G
Published: January 2020

A case of endocarditis caused by Comamonas acidovorans (Pseudomonas acidovorans) in a 42-year-old intravenous-drug abuser is described. This article appears to be the first detailed report of the isolation of this organism from a systemic clinical infection and its identification as a pathogen.
Ghost mycobacteria on Gram stain
Authors: Trifiro S , Bourgault A M , Lebel F , René P
Published: January 2020

The Gram stain is a key tool in diagnostic microbiology. Its usefulness with respect to mycobacteria is undefined. The neutrality of mycobacteria other than Mycobacterium tuberculosis on Gram staining of various clinical specimens is described.
Immunophysical characterization of human isolates of Serratia marcescens
Authors: Hamadeh R M , Mandrell R E , Griffiss J M
Published: January 2020

The immunophysical characteristics of 29 Serratia marcescens strains isolated from hospitalized patients in three different cities were studied. Their outer membrane antigens were compared by solid-phase radioimmunoassay inhibition, and their proteinase K-treated, whole-cell lysates were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis. The strains had a limited number of unique outer membrane lipopolysaccharide (LPS) and capsular polysaccharide (K) antigens. By solid-phase radioimmunoassay inhibition, these strains could be divided into four distinct LPS and five K antigenic groups. By SDS-PAGE, the LPS groups could be further divided into three distinct SDS-PAGE core polysaccharide profiles and five distinct O-side-chain polysaccharide profiles. Immunoblot analysis with rabbit antiserum confirmed the limited heterogeneity of these isolates. Of the strains tested, no PAGE profile was unique to blood or nonblood isolates or to organisms collected from a given hospital. Variability of O and core PAGE profiles was not a function of organism growth cycle. Five representative Serratia strains were tested by SDS-PAGE and immunoblot analysis and in a bactericidal assay with normal human serum. We found that (i) the normal human serum had antibodies to the LPS of each of the strains, (ii) the anti-LPS antibody measured by immunoblot did not correlate with the level of bactericidal activity in the normal human serum, (iii) three of four sepsis isolates were serum sensitive, (iv) two Serratia strains serum sensitive in log-phase growth became serum resistant in late stationary-phase growth and under limiting nutrient conditions, and (v) no LPS PAGE profile distinguished serum-sensitive from serum-resistant strains.
Use of a Chinese hamster ovary cell cytotoxicity assay for the rapid diagnosis of pertussis
Authors: Halperin S A , Bortolussi R , Kasina A , Wort A J
Published: January 2020

A cytotoxicity assay with Chinese hamster ovary cells (CHO) capable of detecting 750 pg of pertussis toxin was assessed for use as a rapid test for the diagnosis of pertussis and compared with direct immunofluorescence (DFA). With pure bacterial cultures and simulated clinical specimens, the CHO assay detected as few as two colonies of Bordetella pertussis; no cytotoxicity occurred with other respiratory tract microorganisms. Next, nasopharyngeal aspirate secretions and nasopharyngeal cultures harvested after 72 h of incubation from 57 culture-positive and 201 culture-negative patients were examined. The CHO assay with nasopharyngeal secretions was positive in 25 (45%) of 55 culture-positive cases; DFA was positive in 15 (26%) of 57 cases (P = 0.05). The CHO assay with 72-h culture washes was positive in 42 (75%) of 57 culture-positive cases (P less than 0.001 compared with DFA). The CHO assay was more specific than DFA; all five CHO-positive, culture-negative cases were confirmed as true positives by serologic or toxin neutralization assays. In contrast, only 4 (36%) of 11 DFA-positive, culture-negative cases were confirmed as pertussis by serologic methods (P = 0.03). Combining the CHO assay with culture significantly decreased the delay in laboratory diagnosis of pertussis (3.30 versus 4.54 days; P = 0.01). The CHO assay is a sensitive and specific assay for the rapid diagnosis of pertussis.
Simplified and accurate nonradioactive polynucleotide gene probe assay for identification of enterotoxigenic Escherichia coli
Authors: Sommerfelt H , Grewal H M , Bhan M K
Published: January 2020

The present study describes a colony hybridization setup for identification of enterotoxigenic Escherichia coli obviating the need for advanced equipment and radioactive isotopes. With a modest laboratory arrangement, polynucleotide gene probes were produced in large quantities. The probes were labeled with digoxigenin and, after hybridization, detected with an antidigoxigenin alkaline phosphatase conjugate. With an established isotope-based oligonucleotide hybridization assay as reference, a blinded study on a large battery of enterotoxigenic and nonenterotoxigenic bacteria revealed a satisfactory sensitivity and specificity of the nonradioactive assay.
Detection of human parvovirus B19 DNA by using the polymerase chain reaction
Authors: Koch W C , Adler S P
Published: January 2020

The polymerase chain reaction (PCR) was investigated for detecting human parvovirus B19 (B19) DNA in sera. Three pairs of oligonucleotides were evaluated as primers. The best oligonucleotide pair spanned 699 nucleotides, including the region common to VP1 and VP2. After PCR amplification of B19 DNA in serum, a 699-nucleotide DNA fragment was detected on agarose gels. This DNA fragment was B19 DNA, because after Southern transfer it hybridized to a 19-nucleotide internal probe and contained a single PstI cleavage site. Dot blot hybridization with a radiolabeled cloned portion of the B19 genome as a probe was compared with PCR. PCR was 10(4) times more sensitive than dot blot hybridization and, with an internal radiolabeled probe, 10(7) times more sensitive than dot blot hybridization. Of 29 serum specimens from 18 patients with proven B19 infections, 24 were PCR positive. None of 20 serum samples from uninfected controls were positive. Of 22 serum samples positive for immunoglobulin M to B19, PCR detected B19 DNA in 17. Seven serum samples lacking immunoglobulin M were PCR positive. PCR detected B19 DNA in urine, amniotic fluid, pleural fluid, ascites, and leukocyte extracts. PCR is a rapid and simple method for diagnosing infections with human parvovirus B19 but must be combined with serologic tests for immunoglobulin M to B19, especially when testing only a single serum sample.
Diversity and stability of restriction enzyme profiles of plasmid DNA from methicillin-resistant Staphylococcus aureus
Authors: Zuccarelli A J , Roy I , Harding G P , Couperus J J
Published: January 2020

Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a significant epidemiological problem. Detecting the sources of epidemic strains and preventing their access to patients, however, depend upon the availability of techniques to reliably distinguish among MRSA strains. We evaluated restriction enzyme analysis of plasmid DNA for use as an epidemiological marker of MRSA strains. The diversity of plasmid types was assessed by examining 120 clinical and environmental MRSA isolates from five southern California hospitals and from the American Type Culture Collection. Thirty-seven distinctive EcoRI digestion patterns were observed. We characterized each strain by the number of plasmids it contained and the sizes of the fragments that were generated by EcoRI. Very few of the isolates (4.2%) lacked plasmids, and some (6.7%) contained DNA that was not digested by EcoRI. Several isolates (12.5%) contained two or more plasmids. We were able to assess the stability of MRSA plasmid types by tracking epidemic strains over a 2-year period. We also examined successive isolates from 10 individual patients during their hospitalization. In all but one case, the patient's plasmid profiles remained unchanged. We conclude that the diversity and stability of MRSA plasmid types make them excellent epidemiological markers. In support of this conclusion, we found that our data provided significant epidemiological insights. Two epidemic strains, accounting for more than half of the infections, were identified in the five hospitals. The remaining cases were sporadic, caused by MRSA strains that appeared very infrequently and that may have originated from sources outside the hospitals.
Rapid biochemical test to identify verocytotoxin-positive strains of Escherichia coli serotype O157
Authors: Thompson J S , Hodge D S , Borczyk A A
Published: January 2020

Fluorogenic procedures were used with the substrate 4-methylumbelliferyl-beta-D-glucuronide (MUG) to identify Escherichia coli. Most strains produced beta-glucuronidase and, thus, were MUG positive. A 20-min procedure was developed to detect glucuronidase activity in 1,295 bacterial cultures, representing 23 genera, of strains that were isolated from clinical specimens. Very few organisms other than E. coli were MUG positive. Of 682 E. coli strains that were isolated, 630 (92.4%) were MUG positive. When an additional 188 E. coli serotype O157 isolates were examined, 155 E. coli O157:H7, 10 E. coli O157:H-, and 1 E. coli O157:H (rough) isolate were MUG negative. All 166 cultures were verocytotoxin positive. Of the remaining 22 E. coli O157 isolates, 2 isolates were O157:H-, 1 isolate was O157:H (rough), and 19 isolates were other H types (H6, H16, H19, H25, H42, and H45); these 22 isolates were MUG positive. All 22 cultures were verocytotoxin negative. The rapid MUG procedure can be used to predict verocytotoxin-positive isolates of E. coli O157; that is, there is a very good likelihood that MUG-negative E. coli O157 isolates are verocytotoxin positive.
Short prereduced anaerobically sterilized (PRAS) biochemical scheme for identification of clinical isolates of bile-resistant Bacteroides species
Authors: Citron D M , Baron E J , Finegold S M , Goldstein E J
Published: January 2020

The rapid identification of isolates of bile-resistant Bacteroides species has clinical and therapeutic relevance because of differences in their patterns of susceptibility and virulence. Five hundred twenty-one strains of bile-resistant Bacteroides species that were previously identified by conventional biochemical methods were reexamined to determine the minimum essential parameters necessary for correct identification. Rapid tests for bile resistance, indole production, and catalase were combined with a novel scheme for biochemical determination of saccharolytic activity on arabinose, trehalose, rhamnose, and/or xylan that included the postincubation addition of bromthymol blue for visual pH determination. Organisms were inoculated into prereduced anaerobically sterilized (PRAS) carbohydrates directly from plates, and identification was complete within 24 h of obtaining a pure culture. Ninety-three percent of bile-resistant Bacteroides species from routine clinical specimens were identified correctly by this scheme; a small number of other indole-positive strains, B. splanchnicus, B. eggerthii, and B. stercoris, were misidentified as B. uniformis.
Occurrence of Clavispora lusitaniae, the teleomorph of Candida lusitaniae, among clinical isolates
Authors: Gargeya I B , Pruitt W R , Simmons R B , Meyer S A , Ahearn D G
Published: January 2020

Of 13 clinical isolates of Candida lusitaniae from diverse geographical regions, 7 represented the mating types (6 alpha, 1 a) of the ascomycete Clavispora lusitaniae. Selected nonfertile isolates showed significant DNA relatedness (greater than 90%) to representatives of both mating types. Phenotypic physiological characteristics, such as cellobiose fermentation and rhamnose assimilation, proved insufficient for separation of Clavispora lusitaniae and Clavispora opuntiae.
Rapid detection of Pneumocystis carinii using a direct fluorescent monoclonal antibody stain
Authors: Ng V L , Virani N A , Chaisson R E , Yajko D M , Sphar H T , Cabrian K , Rollins N , Charache P , Krieger M , Hadley W K
Published: January 2020

A collaborative study was undertaken at two institutions to assess the performance of a direct fluorescent-antibody stain for the detection of Pneumocystis carinii in respiratory specimens from patients with known or suspected human immunodeficiency virus type 1 infections. A total of 163 specimens (125 induced sputa, 37 bronchoalveolar lavage fluids, and 1 tracheal aspirate) from 124 patients were examined by using modified Giemsa (Diff-Quik; Baxter American Scientific Products, Chicago, Ill.) and direct fluorescent-antibody stains. A total of 73 specimens contained P. carinii, which was detected in 66 (92%) of the specimens by using the modified Giemsa and in 71 (97%) of the specimens by using the fluorescent-antibody stain. One bronchoalveolar lavage fluid specimen in which P. carinii was detected only with the fluorescent-antibody stain was determined to be a false-positive based on subsequent clinical evaluation of the patient. Although the overall time for processing and examining specimens stained with either stain was not significantly different for those specimens containing P. carinii, considerably less time was required for microscopic examination of those fluorescent-antibody-stained specimens lacking P. carinii.
Phagocytosis of mastitis isolates of Staphylococcus aureus and expression of type 5 capsular polysaccharide are influenced by growth in the presence of milk
Authors: Sutra L , Rainard P , Poutrel B
Published: January 2020

Phagocytosis by bovine polymorphonuclear granulocytes of seven capsular polysaccharide type 5 Staphylococcus aureus strains isolated from mastitis [corrected] was investigated by means of luminol-dependent chemiluminescence. Bacteria were grown on four different agar media (brain heart infusion, Columbia broth, modified staphylococcus medium 110, and skim milk) and were opsonized by normal bovine serum. When compared to growth on brain heart infusion agar, Columbia agar, and modified staphylococcus medium 110 agar, growth on skim milk agar rendered five of the strains more resistant to opsonization. The other two strains were resistant in all culture media used. Short periods of incubation in milk after growth on brain heart infusion agar did not augment resistance to phagocytosis, indicating that mere adsorption of milk components on bacteria was not responsible. The variability of the chemiluminescence response of polymorphonuclear leukocytes was pronounced among strains with each growth medium except milk. Growth on modified staphylococcus medium 110 and on milk agar favored the masking of teichoic acid, as shown by inagglutinability with rabbit antiserum. Interestingly, agglutination by a monoclonal antibody to capsular polysaccharide type 5 was optimal when bacteria were grown on skim milk agar. This suggests that capsular polysaccharide participated in the masking effect. These findings indicate that masking of the bacterial target of most of the naturally acquired opsonins present in normal bovine serum occurred when bacteria grew in the presence of milk, resulting in an increased resistance to phagocytosis by polymorphonuclear leukocytes.
Detection of colonization factor antigen I-positive enterotoxigenic Escherichia coli with a cloned polynucleotide probe
Authors: Grewal H M , Sommerfelt H , Gaastra W , Svennerholm A M , Bhan M K , Hamers A M , Kumar R , Wiklund G , Bjorvatn B
Published: January 2020

We compared a new colony hybridization assay with an established enzyme-linked immunosorbent assay for detection of enterotoxigenic Escherichia coli (ETEC) expressing colonization factor antigen I (CFA/I). The tests were applied to 135 human ETEC strains. Of these isolates, 30 had previously been characterized for CFAs. A strain harboring the plasmid vector of the polynucleotide gene probe, nine non-ETEC strains from healthy infants, and eight ETEC strains of animal origin were included for further evaluation of probe specificity. The two assays showed a high level of concordance in the specific detection of ETEC strains expressing CFA/I. A total of 24 strains tested positive in the CFA/I hybridization assay, while 23 of those strains were positive in the CFA/I enzyme-linked immunosorbent assay. The single discrepant result could be explained by the loss of a regulatory gene. The strain harboring the plasmid vector of the probe, the non-ETEC E. coli strains, and the ETEC strains of animal origin were all negative in the CFA/I probe assay.
Importance of rotavirus and adenovirus types 40 and 41 in acute gastroenteritis in Korean children
Authors: Kim K H , Yang J M , Joo S I , Cho Y G , Glass R I , Cho Y J
Published: January 2020

To examine the role of rotavirus (Rv) and adenovirus types 40 and 41 (Ad40/41) in Korean children with acute gastroenteritis, we evaluated 345 children with acute gastroenteritis and 90 children without acute gastroenteritis in Seoul, Korea, during a 29-month period. Stools were tested for group A Rv antigen and for Ad40/41 by using monoclonal antibody (MAb)-based assays. Rv was found in 68% of the ill children and 19% of the controls (P less than 0.001), whereas Ad40/41 was detected in 9% of the ill children and 2% of the controls (P less than 0.05). Also, 6% of the ill children and 0.01% of the controls excreted Rv and Ad40/41 simultaneously. Among the ill children, 96% of children with Rv and 94% of those with Ad40/41 were younger than 24 months. Although a peak of Rv infection was detected in early winter in both years of the study, there was no apparent seasonal trend with Ad40/41. Diarrhea with more than 10 stools per day, vomiting, or fever was most strongly associated with Rv shedding, whereas the first two manifestations were associated with coinfection of Rv and Ad40/41. To investigate the genetic and serotypic diversity of Rv strains, we tested 195 and 144 fecal Rv specimens isolated from the gastroenteritis cases, respectively, by polyacrylamide gel electrophoresis of the segmented RNA genome and by an enzyme-linked immunosorbent assay with serotype-specific MAbs. Of the 195 specimens, 154 yielded RNA patterns characteristic of group A Rv: 18% had short electrophoretic migration patterns, 81% had long patterns, and 1% had a mixture of short and long patterns. Of the 144 specimens, serotype specificity was determined in 51%: 89% were serotype 1, 10% were serotype 2, and 1% were serotype 3. Analysis of the specimens for which electropherotypes and serotypes were available indicated that a given RNA pattern corresponded to a particular serotype, except in one strain that showed short patterns but serotype 1. We suggest that Rv and Ad40/41 in stools be accepted critically as an important cause of diarrhea among young children in Korea.
Serological typing of spotted fever group Rickettsia isolates from Zimbabwe
Authors: Kelly P J , Mason P R
Published: January 2020

Eight rickettsialike organisms were isolated in tissue culture from ticks of dogs and cattle from various areas of Zimbabwe. These isolates and a reference strain, Rickettsia conorii Simko, were tested by microimmunofluorescence against homologous and heterologous antisera raised in mice. From the titers obtained by this method, specificity differences (SPDs) were calculated between each of the rickettsiae. Only small serological differences were detected among the isolates from ticks obtained from dogs (mean SPD, 0.5) and also among the isolates from ticks obtained from cattle (mean SPD, 0.3). However, when isolates from ticks obtained from dogs and cattle were compared, the serological differences were greater (mean SPD, 1.3). The isolates from ticks obtained from dogs were found to be very similar serologically to the Simko strain of R. conorii (mean SPD, 0.8), while three of four isolates from ticks obtained from cattle were different enough (SPD, greater than or equal to 3) to be identified as separate serotypes. These findings indicate that there is a high degree of antigenic heterogeneity among the tick-transmitted spotted fever group rickettsiae in Zimbabwe.
Bovine lactoferrin binding to six species of coagulase-negative staphylococci isolated from bovine intramammary infections
Authors: Naidu A S , Miedzobrodzki J , Andersson M , Nilsson L E , Forsgren A , Watts J L
Published: January 2020

Bovine lactoferrin (BLf), an acute-phase iron-binding secretory protein present in secretions of the bovine udder, was demonstrated to bind to the following staphylococcal species associated with bovine intramammary infections: S. epidermidis, S. warneri, S. hominis, S. xylosus, S. hyicus, and S. chromogenes. The degree of 125I-labeled BLf uptake significantly varied among the blood agar-grown cells of all six species of coagulase-negative staphylococci tested. Isolates identified as S. xylosus demonstrated the highest (mean, 35.1 x 10(6) +/- 13.3 x 10(6) nmol) and S. hyicus the lowest (mean, 10.7 x 10(6) +/- 5.9 x 10(6) nmol) binding to 125I-BLf. BLf binding was optimum at an acidic pH, with time-dependent binding saturation ranging from 70 min for S. warneri to 240 min for S. hominis. The BLf-binding mechanism was specific, with affinity constants (Ka values) ranging between 0.96 x 10(6) and 11.90 x 10(6) liters/mol. The numbers of BLf-binding sites per cell, as determined by using Scatchard analysis, were as follows: S. epidermidis, 3,600; S. warneri, 1,900; S. hominis, 4,100; S. xylosus, 4,400; S. hyicus, 6,100; and S. chromogenes, 4,700. 125I-BLf binding to all species was inhibited by unlabled BLf and unlabeled human lactoferrin, whereas none of the various plasma, connective tissue, or mucosal secretory proteins or carbohydrates tested caused significant interference. BLf-binding receptors of the six coagulase-negative staphylococcal species demonstrated marked differences in patterns of susceptibility to proteolytic or glycolytic enzyme digestion and to heat or periodate treatment. These data suggest that the BLf-binding components in S. epidermidis and S. warneri are proteins containing glycosidyl residues. In the remaining four species, the proteinaceous nature of the BLf-binding component was evident, but the involvement of glycosidyl residues was not clear. Results of this study establish the presence of specific binding components for BLf on coagulase-negative staphylococci isolated from bovine intramammary infections.
Importance of membrane-bound antigens of Toxoplasma gondii and their fixation for serodiagnosis of toxoplasmic encephalitis in patients with acquired immunodeficiency syndrome
Authors: Suzuki Y , Remington J S
Published: January 2020

Titers in a direct agglutination test using Formalin-fixed toxoplasma tachyzoites were significantly higher in patients with acquired immunodeficiency syndrome with toxoplasmic encephalitis (TE) than in those without TE. In contrast, when fresh (not fixed) tachyzoites were used, the titers did not differ from those in patients without TE. The direct agglutination test using Formalin-fixed tachyzoites better distinguished between patients with TE and those without TE than an agglutination test using latex particles coated with Formalin-fixed sonicated-tachyzoite antigens. Thus, both selective use of membrane-bound antigens and their fixation are important for serodiagnosis of TE in patients with acquired immunodeficiency syndrome.
Human herpesvirus 6 inhibits human immunodeficiency virus type 1 replication in cell culture
Authors: Levy J A , Landay A , Lennette E T
Published: January 2020

The SF strain of human herpesvirus 6 (HHV-6SF) isolated from the saliva of a human immunodeficiency virus (HIV)-infected individual was shown to inhibit HIV type 1 (HIV-1) replication in both peripheral blood mononuclear cells and purified CD4+ lymphocytes. This suppression of HIV-1 replication led to decreased cytopathic effects of HIV-1 and prolonged survival of CD4+ cells in culture. Even low levels of HHV-6 added to peripheral blood mononuclear cells showed an inhibitory effect on HIV-1 replication. These results differ from those previously reported showing enhanced HIV-1 production following infection with another strain of HHV-6.
Microagglutination test for early and specific serodiagnosis of tularemia
Authors: Sato T , Fujita H , Ohara Y , Homma M
Published: January 2020

A microagglutination test with safranin-stained Francisella tularensis antigen was compared with a conventional tube agglutination test for the serodiagnosis of tularemia. The microagglutination test was performed in round-bottom microtiter plates by using 0.025 ml of the antisera and of the antigen. The antibody titers obtained by using the microagglutination test were 8 to 64 times higher than those seen with the tube agglutination. By the microagglutination test, the serum agglutinins were detected 3 days earlier in rabbits and 9 days earlier in humans than by the tube agglutination test. The microagglutination test also detected residual circulating antibodies in humans more than 20 years after recovery from infection. These early agglutinins were shown to be in the immunoglobulin M class because of their sensitivities to 2-mercaptoethanol. No significant group agglutination reaction with Brucella abortus was observed. These observations indicate that the microagglutination test is a useful tool for the early and specific serodiagnosis of tularemia.
Detection of pYV+ Yersinia enterocolitica isolates by P1 slide agglutination
Authors: Sory M P , Tollenaere J , Laszlo C , Biot T , Cornelis G R , Wauters G
Published: January 2020

Rabbit polyclonal antisera were raised against the pYV-encoded outer membrane protein P1 of five Yersinia enterocolitica strains belonging to serogroups O:3, O:5,27, O:8, and O:9. Analysis of these strains with the sera showed that P1 presented at least six different antigenic factors. Two of the serum specimens were chosen to test the P1 agglutinability of 797 strains isolated from various sources. This technique appeared to be more reliable than autoagglutination and Ca2+ dependency to monitor the presence of the pYV plasmid. Hence, we propose this P1-mediated agglutination as a new and easy virulence test.
Association of production of cell-detaching factor with the clinical presentation of Trichomonas vaginalis
Authors: Garber G E , Lemchuk-Favel L T
Published: January 2020

Recent work has shown that Trichomonas vaginalis produces a cell-detaching factor (CDF) that causes detachment of monolayer cells in vitro. To study the role of CDF as a pathogenic marker of disease, we studied the production of CDF in 12 clinical isolates of T. vaginalis. These isolates were also utilized in the mouse subcutaneous assay of Honigberg, which is the standard for pathogenicity of T. vaginalis. The isolates were divided into three groups based on clinical presentation (asymptomatic [n = 4], moderate [n = 4], and severe symptoms [n = 4]). CDF was assessed by harvesting the supernatant from the growth of T. vaginalis in cell culture and filtering the supernatant through a 0.45-microns-pore-size filter. The filtrate was applied in a microtiter cytotoxicity assay. The mouse subcutaneous assay did not significantly differentiate among the isolates. However, CDF was strongly associated with clinical presentation by two-way, repeated-measure analysis of variance (P = 0.025). Thus, CDF appears to correlate with clinical presentation and may be an important virulence marker in T. vaginalis pathogenesis.
Comparison of four methods for rapid detection of Pneumocystis carinii in respiratory specimens
Authors: Cregan P , Yamamoto A , Lum A , VanDerHeide T , MacDonald M , Pulliam L
Published: January 2020

Four stains for the detection of Pneumocystis carinii in respiratory specimens were compared for sensitivity, specificity, preparation time, and ease of interpretation. One hundred specimens were collected. Of these, 50 were induced sputum specimens and 50 were bronchoalveolar lavage fluid. All specimens were stained with Diff-Quik (DQ) (a modified Giemsa stain), a quick silver stain, and direct and indirect immunofluorescence stains. A positive specimen was defined as any smear positive by two or more of the methods. Fifty-eight percent of specimens were positive. Seventy-four percent of the sputum specimens and 42% of the bronchoalveolar lavages were positive. The sensitivities for detection of P. carinii in sputum were 92% with silver stain, 97% with direct immunofluorescence assay (DFA), 97% with indirect immunofluorescence assay (IFA), and 92% with DQ. The sensitivities for detection in bronchoalveolar lavage were 86% with silver stain, 90% with DFA, 86% with IFA, and 81% with DQ. Preparation times varied from 90 min for the silver stain and IFA to 3 min for DQ. Costs of the tests varied from $1.50 per slide for DQ to $10.00 per slide for the silver stain and DFA. Reading times varied from 10 to 30 min for the silver stain and DQ to less than 5 min for the immunofluorescence assays. We conclude that all of these tests are viable options for the clinical laboratory, and the choice will be influenced by factors such as clinical volume, ability to batch specimens, and expertise of technological support. A reasonable option may be to use the quick and inexpensive DQ as a screening test and to confirm negative smears with a more sensitive assay.
Direct detection of Mycobacterium tuberculosis in clinical specimens by DNA amplification
Authors: De Wit D , Steyn L , Shoemaker S , Sogin M
Published: January 2020

A polymerase chain reaction assay was developed for the amplification of a 336-bp repetitive fragment in the chromosome of Mycobacterium tuberculosis. The assay is specific for M. tuberculosis and can be used to detect the amount of DNA present in less than 10 organisms. It was used to demonstrate M. tuberculosis DNA in 14 of 26 clinical specimens (from cerebrospinal fluids, pleural fluid aspirates and biopsies, pericardial fluid aspirates, and an open lung biopsy), and it was shown to be at least as sensitive as conventional culture techniques with these specimens.
Characterization of prototype and clinically defined strains of Streptococcus suis by genomic fingerprinting
Authors: Mogollon J D , Pijoan C , Murtaugh M P , Kaplan E L , Collins J E , Cleary P P
Published: January 2020

A collection of Streptococcus suis strains from animal and human infections was examined for DNA-banding patterns after restriction endonuclease digestion and agarose gel electrophoresis. The endonuclease HaeIII produced the most discriminating restriction profiles among 23 serotypes studied. DNA from serotypes 9, 11, 12, and 16 was resistant to HaeIII cleavage. DNA from serotypes 9 through 16 was cleaved with HindIII and showed substantial genomic differences. We also examined 106 epidemiologically unrelated strains isolated from cases of pig meningitis or pneumonia and 5 strains isolated from cases of human meningitis in order to compare genomic fingerprinting and serotyping as epidemiological tools. Heterogeneity was found among fingerprints of serologically identical isolates, indicating genetic diversity within some serotypes. DNA fingerprints of some serotype 2 strains from different sources appeared identical, suggesting a clonal relationship among strains of this serotype. The data suggest that this technique represents an important tool for examining the natural history of disease caused by S. suis.
Enumeration of mutans streptococci in clinical samples by using monoclonal antibodies
Authors: de Soet J J , van Dalen P J , Pavicic M J , de Graaff J
Published: January 2020

Mutans streptococci have been strongly associated with dental caries. Two members of this group of bacteria, Streptococcus mutans and Streptococcus sobrinus, are often found in human dental plaque. Identification of mutans streptococci on the basis of sugar fermentation is troublesome and easily leads to erroneous conclusions. Furthermore, the recovery on selective media differs for different species. This causes incorrect enumeration of S. mutans and S. sobrinus in clinical samples. The aim of this study was to develop a method for simultaneous identification and enumeration of S. mutans and S. sobrinus in dental plaque and saliva samples. With this immunoblot technique (IBT), significantly more plaque samples containing S. sobrinus were detected than on the selective medium Trypticase-yeast-cysteine-sucrose-bacitracin agar (TYCSB) (P less than 0.01). The numbers of plaque samples harboring S. mutans were equal on TYCSB and by IBT. However, the numbers of CFU of S.mutans as well as of S. sobrinus detected with the IBT were significantly higher than those obtained on TYCSB (P less than 0.001). The recovery of primary isolations of S. sobrinus on TYCSB seems to have been inhibited in 26 of the 45 S. sobrinus-containing plaque samples. False-positive or false-negative reactions with the IBT were not found.
Use of sequential enzyme immunoassay and direct fluorescent antibody tests for detection of Chlamydia trachomatis infections in women
Authors: Schwebke J R , Stamm W E , Handsfield H H
Published: January 2020

Endocervical infections due to Chlamydia trachomatis remain difficult to diagnose due to the lack of an inexpensive, rapid, and accurate test. We evaluated an alternative strategy for diagnosis in which initial screening was performed with an enzyme immunoassay (Chlamydiazyme) followed by a direct fluorescent antibody (DFA) test on specimens in which the Chlamydiazyme optical density (OD) reading fell in an intermediate zone. Lowering the Chlamydiazme OD ratio (specimen to control) used to define a positive test from 1.0 (the ratio suggested by the manufacturer) to 0.3 raised the sensitivity of Chlamydiazyme from 73 to 83%. Confirmation of those specimens having OD ratios of 0.3 to 0.99 by DFA testing increased the specificity of Chlamydiazyme from 95 to 100%. This strategy necessitated performance of the DFA test on 5% of the specimens. Lowering the cutoff OD ratio below 0.3 increased the sensitivity even further but required DFA testing on greater than 25% of the specimens. Use of an adjusted positive cutoff value for defining positive enzyme immunoassays followed by DFA confirmation for intermediate-zone readings may be a feasible approach for some laboratories that lack cell culture facilities.
Enzyme-linked immunoassay for detection of Cryptosporidium antigens in fecal specimens
Authors: Ungar B L
Published: January 2020

Cryptosporidium sp. is a ubiquitous 4- to 6-micron protozoan parasite infecting the intestinal tract of humans. It causes mild to fulminant diarrhea in patients, especially immunocompromised persons, and it may be hard to detect by microscopic fecal examination. An indirect, double-antibody enzyme-linked immunosorbent assay (ELISA) was developed using specifically produced goat and rabbit antisera to detect Cryptosporidium antigens in human feces. Of 62 frozen stools from patients with cryptosporidiosis, as detected by at least two microscopic diagnostic techniques, 51 were positive by ELISA; all ELISA-negative specimens came from patients with fewer than five oocysts per 0.01 ml of concentrated fecal sample examined after modified acid-fast or fluorescent monoclonal antibody staining. A total of 182 specimens from persons without Cryptosporidium infection were negative by ELISA in 176 instances; 3 ELISA-positive specimens came from patients with cryptosporidiosis diagnosed earlier. The sensitivity of the assay was 82.3%, and specificity was 96.7%. The predictive value of a positive ELISA was 89.5%, and the predictive value of a negative ELISA was 94.2%. The ELISA was not affected by the presence of eight other intestinal parasites but was sometimes affected by repeated freezing and thawing of fecal specimens. All fecal specimens were heated to 100 degrees C for 2 min to reduce proteolytic enzyme activity, although the necessity of this step needs further evaluation. This first-generation ELISA is a simple, rapid, easily standardized test for Cryptosporidium antigens in stool samples which will be useful for diagnosis and for large-scale epidemiologic studies.
Enhanced radiometric detection of Mycobacterium paratuberculosis by using filter-concentrated bovine fecal specimens
Authors: Collins M T , Kenefick K B , Sockett D C , Lambrecht R S , McDonald J , Jorgensen J B
Published: January 2020

A commercial radiometric medium, BACTEC 12B, was modified by addition of mycobactin, egg yolk suspension, and antibiotics (vancomycin, amphotericin B, and nalidixic acid). Decontaminated bovine fecal specimens were filter concentrated by using 3-microns-pore-size, 13-mm-diameter polycarbonate filters, and the entire filter was placed into the radiometric broth. Comparison of the radiometric technique with conventional methods on 603 cattle from 9 Mycobacterium paratuberculosis-infected herds found that of 75 positive specimens, the radiometric technique detected 92% while conventional methods detected 60% (P less than 0.0005). Only 3.9% of radiometric cultures were contaminated. To measure the effect of filter concentration of specimens on the detection rate, 5 cattle with minimal and 5 with moderate ileum histopathology were sampled weekly for 3 weeks. M. paratuberculosis was detected in 33.3% of nonfiltered specimens and 76.7% of filtered specimens (P less than 0.005). Detection rates were directly correlated with the severity of disease, and the advantage of specimen concentration was greatest on fecal specimens from cattle with low-grade infections. Detection times were also correlated with infection severity: 13.4 +/- 5.9 days with smear-positive specimens, 27.9 +/- 8.7 days with feces from cows with typical subclinical infections, and 38.7 +/- 3.8 days with fecal specimens from cows with low-grade infections. Use of a cocktail of vancomycin, amphotericin B, and nalidixic acid for selective suppression of nonmycobacterial contaminants was better than the commercial product PANTA (Becton Dickinson Microbiologic Systems, Towson, Md.) only when specimens contained very low numbers of M. paratuberculosis. Radiometric culture of filter-concentrated specimens generally doubled the number of positive fecal specimens detected over conventional methods, making it a useful tool for diagnosis and control of bovine paratuberculosis.