bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Chromosome Underreplication on Cell Division in
Escherichia coli
Authors: Botello Emilia , Nordström Kurt 
Published: March 2020

ABSTRACT

The key processes of the bacterial cell cycle are controlled and coordinated to match cellular mass growth. We have studied the coordination between replication and cell division by using a temperature-controlled
Escherichia coli intR1
strain. In this strain, the initiation time for chromosome replication can be displaced to later (underreplication) or earlier (overreplication) times in the cell cycle. We used underreplication conditions to study the response of cell division to a delayed initiation of replication. The bacteria were grown exponentially at 39°C (normal DNA/mass ratio) and shifted to 38 and 37°C. In the last two cases, new, stable, lower DNA/mass ratios were obtained. The rate of replication elongation was not affected under these conditions. At increasing degrees of underreplication, increasing proportions of the cells became elongated. Cell division took place in the middle in cells of normal size, whereas the longer cells divided at twice that size to produce one daughter cell of normal size and one three times as big. The elongated cells often produced one daughter cell lacking a chromosome; this was always the smallest daughter cells, and it was the size of a normal newborn cell. These results favor a model in which cell division takes place at only distinct cell sizes. Furthermore, the elongated cells had a lower probability of dividing than the cells of normal size, and they often contained more than two nucleoids. This suggests that for cell division to occur, not only must replication and nucleoid partitioning be completed, but also the DNA/mass ratio must be above a certain threshold value. Our data support the ideas that cell division has its own control system and that there is a checkpoint at which cell division may be abolished if previous key cell cycle processes have not run to completion.
Short-Term Regulation of Nitrogenase Activity by NH
4
+
in
Rhodobacter capsulatus
: Multiple In Vivo Nitrogenase Responses to NH
4
+
Addition
Authors: Yakunin Alexander F. , Hallenbeck Patrick C. 
Published: March 2020

ABSTRACT

The photosynthetic bacterium
Rhodobacter capsulatus
has been shown to carry out nitrogenase “switch-off,” a rapid, reversible inhibition of in vivo activity. Here, we demonstrate that highly nitrogen-limited cultures of both the wild-type strain and a
draT draG
mutant are capable of nitrogenase switch-off while moderately nitrogen-limited cultures show instead a “magnitude” response, with a decrease in in vivo nitrogenase activity that is proportional to the amount of added NH
4
+
.
EnterohemorrhagicEscherichia coli(EHEC) Strains of Serogroup O118 Display Three Distinctive Clonal Groups of EHEC Pathogens
Authors: Wieler Lothar H. , Busse Barbara , Steinrück Hartmut , Beutin Lothar , Weber Albert , Karch Helge , Baljer Georg 
Published: March 2020

ABSTRACTA recent case report of a child infected with enterohemorrhagicEscherichia coli(EHEC) of serotype O118:H16 in Bavaria, in association with the isolation of a bovine O118 strain on the same farm (A. Weber, H. Klie, H. Richter, P. Gallien, M. Timm, and K. W. Perlberg, Berl. Muench. Tieraerztl. Wochenschr. 110:211–213, 1997), prompted us to investigate the relationship between bovine and human strains of serogroup O118. A total of 29 human O118E. colistrains from Europe (21), Canada (4), and Peru (4) were compared by virulence typing and macrorestriction analysis with 7 bovine O118 EHEC strains isolated in Bavaria. Twenty-five of the human strains were characterized as EHEC. By serotyping and determination of the virulence-associated factors Shiga toxin (stx1 stx2 stx2variants), intimin (eae), and EHEC hemolysin (HlyEHEC), three distinctive groups of O118 human pathogens were identified. Most of the strains belonged to serotype O118:H16, displaying the virulence traits Stx1, intimin, HlyEHEC, and EspP/PssA (group 1). In addition, we identified strains of serotype O118:H12 (Stx2d only; group 2) and of serotype O118:H30 (Stx2 and intimin; group 3). Macrorestriction analysis withBlnI andXbaI revealed that all strains with a single O118 serotype profile (O118:H12, O118:H16, and O118:H30) belonged to one clonal cluster, irrespective of their origin. Group 1 strains clustered in the same clonal group as the bovine O118:H16 strains. Moreover, four pairs of strains of different origins and indistinguishable by all other methods applied were identified as group 1 strains. Our data support the direct transmission of an EHEC O118:H16 strain from a calf to a 2-year-old boy in the above-mentioned case report. Since bovine and human O118:H16 strains represent the same clones, they must be considered zoonotic EHEC pathogens. In contrast, EHEC strains of serotypes O118:H12 and O118:H30 have been isolated only from humans, indicating a reservoir for certain human O118 EHEC strains other than bovines.
Evaluation of Three Rapid Methods for Detection of Methicillin Resistance inStaphylococcus aureus
Authors: Louie L. , Matsumura S. O. , Choi E. , Louie M. , Simor A. E. 
Published: March 2020

ABSTRACTThe probe-based Velogene Rapid MRSA Identification Assay (ID Biomedical Corp., Vancouver, British Columbia, Canada) and the latex agglutination MRSA-Screen (Denka Seiken Co., Tokyo, Japan) were evaluated for their ability to identify methicillin-resistantStaphylococcus aureus(MRSA) and to distinguish strains of MRSA from borderline oxacillin-resistantS. aureus(BORSA;mecA-negative, oxacillin MICs of 2 to 8 μg/ml). The Velogene is a 90-min assay using a chimeric probe to detect themecAgene. MRSA-Screen is a 15-min latex agglutination test with penicillin-binding protein 2a antibody-sensitized latex particles. We compared these assays with the BBL Crystal MRSA ID System (Becton Dickinson, Cockeysville, Md.) and with PCR formecAgene detection. A total of 397 clinical isolates ofS. aureuswere tested, consisting of 164 methicillin-susceptible strains, 197 MRSA strains, and 37 BORSA strains. All assays performed well for the identification of MRSA with sensitivities and specificities for Velogene, MRSA-Screen, and BBL Crystal MRSA ID of 98.5 and 100%, 98.5 and 100%, and 98.5 and 98%, respectively. Three MRSA strains were not correctly identified by each of the Velogene and MRSA-Screen assays, but repeat testing with a larger inoculum resolved the discrepancies. The BBL Crystal MRSA ID test misclassified four BORSA strains as MRSA. Both the Velogene and the MRSA-Screen assays are easy to perform, can accurately differentiate BORSA isolates from MRSA isolates, and provide a rapid alternative for the detection of methicillin resistance inS. aureusin clinical laboratories, especially whenmecAPCR gene detection is unavailable.
Comparison of Serologic Assays and PCR for Diagnosis of Human Herpesvirus 8 Infection
Authors: Spira Thomas J. , Lam Lee , Dollard Sheila C. , Meng Yuan-Xiang , Pau Chou Pong , Black Jodi B. , Burns Darrell , Cooper Brian , Hamid Melissa , Huong Joe , Kite-Powell Kathleen , Pellett Philip E. 
Published: March 2020

ABSTRACT

A variety of assays for the diagnosis human herpesvirus 8 (HHV-8) infection have been reported. We compared several such assays with a panel of 88 specimens from human immunodeficiency virus (HIV)-infected patients with Kaposi's sarcoma (KS) (current-KS patients;
n
= 30), HIV-infected patients who later developed KS (later-KS patients;
n
= 13), HIV-infected patients without KS (no-KS patients;
n
= 25), and healthy blood donors (
n
= 20). PCR assays were also performed with purified peripheral blood mononuclear cells (PBMCs) to confirm positive serologic test results. The order of sensitivity of the serologic assays (most to least) in detecting HHV-8 infection in current-KS patients was the mouse monoclonal antibody-enhanced immunofluorescence assay (MIFA) for lytic antigen (97%), the orfK8.1 peptide enzyme immunoassay (EIA) (87%), the orf65 peptide EIA (87%), MIFA for latent antigen (83%), the Advanced Biotechnologies, Inc., EIA (80%), and the orf65 immunoblot assay (80%). Combination of the results of the two peptide EIAs (combined peptide EIAs) increased the sensitivity to 93%. For detection of infection in later-KS patients, the MIFA for lytic antigen (100%), the orfK8.1 peptide EIA (85%), and combined peptide EIAs (92%) were the most sensitive. Smaller percentages of no-KS patients were found to be positive (16 to 56%). Most positive specimens from the current-KS and later-KS groups were positive by multiple assays, while positive specimens from the no-KS group tended to be positive only by a single assay. PCR with PBMCs for portions of the HHV-8 orf65 and gB genes were positive for less than half of current-KS and later-KS patients and even fewer of the no-KS patients. The concordance between serologic assays was high. We propose screening by the combined peptide EIAs. For specimens that test weakly positive, we recommend that MIFA for lytic antigen be done. A positive result with a titer of ≥1:40 would be called HHV-8 positive. A negative or low titer would be called HHV-8 negative. If a population has a high percentage of persons who test positive by the combined peptide EIAs, then a MIFA could be performed with the negative specimens to determine if any positive specimens are being missed. Alternatively, if a population has a low percentage that test positive, then a MIFA could be performed with a subset of the negative specimens for the same reason. As described above, only a titer of ≥1:40 would be considered HHV-8 positive.
Evaluation of IS200-PCR and Comparison with Other Molecular Markers To TraceSalmonella entericasubsp.entericaSerotype Typhimurium Bovine Isolates from Farm to Meat
Authors: Millemann Yves , Gaubert Stéphane , Remy Dominique , Colmin Catherine 
Published: March 2020

ABSTRACTA procedure that uses an original molecular marker (IS200-PCR) and that is based on the amplification of DNA with outward-facing primers complementary to each end of IS200has been evaluated with a collection of 85Salmonella entericasubsp.entericaserotype Typhimurium isolates. These strains were isolated from a group of 10 cows at different stages: during transportation between the farm and the slaughterhouse, on the slaughter line, from the environment, and from the final product (ground beef). The 85 isolates were characterized by their antibiotic resistance patterns and were compared by IS200-PCR and by use of four other genotypic markers. Those markers included restriction profiles for 16S and 23S rRNA (ribotypes) and amplification profiles obtained by different approaches: random amplified polymorphic DNA analysis, enterobacterial repetitive intergenic consensus PCR, and PCR ribotyping. The results of the IS200-PCR were in accordance with those of other molecular typing methods for this collection of isolates. Five different genotypes were found, which made it possible to refine the hypotheses on transmission obtained from phenotypic results. The genotyping results indicated the massive contamination of the whole group of animals and of the environment by one clonal strain originally recovered from one cow that excreted the strain. On the other hand, a few animals and their environment appeared to be simultaneously contaminated with genetically different strains.
A Comparison of Seven Tests for Serological Diagnosis of Tuberculosis
Authors: Pottumarthy Sudha , Wells Virginia C. , Morris Arthur J. 
Published: March 2020

ABSTRACT

Seven serological tests, two immunochromatographic tests, ICT Tuberculosis and RAPID TEST TB, and five enzyme-linked immunosorbent assays, TUBERCULOSIS IgA EIA, PATHOZYME-TB complex, PATHOZYME-MYCO IgG, PATHOZYME-MYCO IgA, and PATHOZYME-MYCO IgM, were evaluated simultaneously with 298 serum samples from three groups of individuals: 44 patients with active tuberculosis, 204 controls who had undergone the Mantoux test (89 Mantoux test-positive and 115 Mantoux test-negative controls), and 50 anonymous controls. The sensitivities of the tests with sera from patients with active tuberculosis were poor to modest, ranging from 16 to 57%. All the tests performed equally with sera from subgroups of those with active tuberculosis, those with pulmonary (33 patients) versus extrapulmonary (11 patients) disease, and those who were smear positive (24 patients) versus smear negative (12 patients) (
P
> 0.05). The specificities of the tests ranged from 80 to 97% with sera from the Mantoux test controls and 62 to 100% with sera from the anonymous controls. The TUBERCULOSIS IgA EIA had the highest sensitivity (57%) with sera from patients with active tuberculosis, with a high specificity of 93% with sera from the Mantoux test controls, but a very poor specificity of 62% with sera from the anonymous controls. Overall, ICT Tuberculosis followed by PATHOZYME-MYCO IgG had the best performance characteristics, with sensitivities of 41 and 55%, respectively, with sera from patients with active tuberculosis and specificities of 96 and 89%, respectively, with sera from the Mantoux test controls and 88 and 90%, respectively, with sera from the anonymous controls. By combining all the test results, a maximum sensitivity of 84% was obtained, with reciprocal drops in specificities to 55 and 42% for the Mantoux test controls and anonymous controls, respectively. The best combination was that of ICT Tuberculosis and PATHOZYME-MYCO IgG, with a sensitivity of 66% and a specificity of 86% for the Mantoux test controls and a sensitivity and specificity of 78% for the anonymous controls. While a negative result by any one of these tests would be useful in helping to exclude disease in a population with a low prevalence of tuberculosis, a positive result may aid in clinical decision making when applied to symptomatic patients being evaluated for active tuberculosis.
A Survey of Stool Culturing Practices for
Vibrio
Species at Clinical Laboratories in Gulf Coast States
Authors: Marano Nina N. , Daniels Nicholas A. , Easton Alyssa N. , McShan Andre , Ray Beverly , Wells Joy G. , Griffin Patricia M. , Angulo Frederick J. 
Published: March 2020

ABSTRACT

Non-cholera
Vibrio
infections are an important public health problem. Non-cholera
Vibrio
species usually cause sporadic infections, often in coastal states, and have also caused several recent nationwide outbreaks of gastroenteritis in the United States. We report a survey of laboratory stool culturing practices for
Vibrio
among randomly selected clinical laboratories in Gulf Coast states (Alabama, Florida, Louisiana, Mississippi, and Texas). Interviews conducted with the microbiology supervisors of 201 clinical laboratories found that 164 (82%) received stool specimens for culture. Of these, 102 (62%) of 164 processed stool specimens on site, and 20 (20%) of these 102 laboratories cultured all stool specimens for
Vibrio
, indicating that at least 34,463 (22%) of 152,797 stool specimens were cultured for
Vibrio
. This survey suggests that despite an increased incidence of non-cholera
Vibrio
infections in Gulf Coast states, a low percentage of clinical laboratories routinely screen all stool specimens, and fewer than 25% of stool specimens collected are routinely screened for non-cholera
Vibrio
.
Extraction-Free, Filter-Based Template Preparation for Rapid and Sensitive PCR Detection of Pathogenic Parasitic Protozoa
Authors: Orlandi Palmer A. , Lampel Keith A. 
Published: March 2020

ABSTRACT

Within the last several years, the protozoan parasites
Cyclospora cayetanensis
,
Cryptosporidium parvum
, and microsporidia have become recognized as important, rapidly emerging human pathogens in immunocompromised and immunocompetent individuals. Since the early 1990s, many of the reported outbreaks of enteric illness caused by these microorganisms have been attributed to food- and water-borne contamination. Many inherent obstacles affect the success of current surveillance and detection methods used to monitor and control levels of contamination by these pathogens. Unlike methods that incorporate preenrichment for easier and unambiguous identification of bacterial pathogens, similar methods for the detection of parasitic protozoa either are not currently available or cannot be performed in a timely manner. We have developed an extraction-free, filter-based protocol to prepare DNA templates for use in PCR to identify
C. cayetanensis
and
C. parvum
oocysts and microsporidia spores. This method requires only minimal preparation to partially purify and concentrate isolates prior to filter application. DNA template preparation is rapid, efficient, and reproducible. As few as 3 to 10 parasites could be detected by PCR from direct application to the filters. In studies, as few 10 to 50
Encephalitozoon intestinalis
spores could be detected when seeded in a 100-μl stool sample and 10 to 30
C. cayetanensis
oocysts could be detected per 100 g of fresh raspberries. This protocol can easily be adapted to detect parasites from a wide variety of food, clinical, and environmental samples and can be used in multiplex PCR applications.
Urogenital
Chlamydia trachomatis
Serovars in Men and Women with a Symptomatic or Asymptomatic Infection: an Association with Clinical Manifestations?
Authors: Morré S. A. , Rozendaal L. , van Valkengoed I. G. M. , Boeke A. J. P. , van Voorst Vader P. C. , Schirm J. , de Blok S. , van den Hoek J. A. R. , van Doornum G. J. J. , Meijer C. J. L. M. , van den Brule A. J. C. 
Published: March 2020

ABSTRACT

To determine whether certain
Chlamydia trachomatis
serovars are preferentially associated with a symptomatic or an asymptomatic course of infection,
C. trachomatis
serovar distributions were analyzed in symptomatically and asymptomatically infected persons. Furthermore, a possible association between
C. trachomatis
serovars and specific clinical symptoms was investigated.
C. trachomatis
-positive urine specimens from 219 asymptomatically infected men and women were obtained from population-based screening programs in Amsterdam. Two hundred twenty-one
C. trachomatis
-positive cervical and urethral swabs from symptomatically and asymptomatically infected men and women were obtained from several hospital-based departments. Serovars were determined using PCR-based genotyping, i.e., restriction fragment length polymorphism analysis of the nested-PCR-amplified
omp1
gene. The most prevalent
C. trachomatis
serovars, D, E, and F, showed no association with either a symptomatic or asymptomatic course of infection. The most prominent differences found were (i) the association of serovar Ga with symptoms in men (
P
= 0.0027), specifically, dysuria (
P
< 0.0001), and (ii) detection of serovar Ia more often in asymptomatically infected people (men and women) (
P
= 0.035). Furthermore, in women, serovar K was associated with vaginal discharge (
P
= 0.002) and serovar variants were found only in women (
P
= 0.045).
Atypical Lipid-Dependent
Malassezia
Species Isolated from Dogs with Otitis Externa
Authors: Crespo M. J. , Abarca M. L. , Cabañes F. J. 
Published: March 2020

ABSTRACT

During a survey of the occurrence of
Malassezia
species in the external ear canals of dogs with chronic otitis externa, lipid-dependent
Malassezia
species were isolated in three dogs. These species were identified as
Malassezia furfur
and
M. obtusa
but showed atypical assimilation patterns. To our knowledge, this is the first report of the isolation of lipid-dependent species of the genus
Malassezia
in association with canine otitis.
Comparison of Recoveries of
Mycobacterium tuberculosis
Using the Automated BACTEC MGIT 960 System, the BACTEC 460 TB System, and Löwenstein-Jensen Medium
Authors: Somoskövi Ákos , Ködmön Csaba , Lantos Ákos , Bártfai Zoltán , Tamási Lilla , Füzy Judit , Magyar Pál 
Published: March 2020

ABSTRACT

Using two different liquid media and one conventional solid medium, a total of 57 mycobacterial isolates (
Mycobacterium tuberculosis
,
n
= 55; nontuberculous mycobacteria,
n
= 2) were recovered from 377 clinical specimens. The rates of recovery of
M. tuberculosis
were 96.4% with the BACTEC MGIT 960 liquid medium, 92.7% with BACTEC 12B liquid medium, and 81.8% with the Löwenstein-Jensen (LJ) medium. The mean time to detection of
M. tuberculosis
in smear-positive specimens was 12.6 days for BACTEC MGIT 960 medium, 13.8 days for BACTEC 12B medium, and 20.1 days for LJ medium, and in smear-negative specimens it was 15.8 days for BACTEC MGIT 960 medium, 17.7 days for BACTEC 12B medium, and 42.2 days for LJ medium. The rates of contamination were 3.7, 2.9, and 1.2% for the BACTEC MGIT 960, BACTEC 12B, and LJ media, respectively. In conclusion, the nonradiometric, fully automated 7-ml BACTEC MGIT 960 system can be considered a viable alternative to the semiautomated, radiometric BACTEC 460 TB system.
Retrospective Diagnosis of Diphtheria by Detection of the
Corynebacterium diphtheriae tox
Gene in a Formaldehyde-Fixed Throat Swab Using PCR and Sequencing Analysis
Authors: Komiya Takako , Shibata Naohiro , Ito Masafumi , Takahashi Motohide , Arakawa Yoshichika 
Published: March 2020

ABSTRACT

The
tox
gene of
Corynebacterium diphtheriae
was detected in a formaldehyde-fixed throat swab taken from a 68-year-old man who was reported to have died of suffocation due to a pharyngeal tumor. DNA templates prepared from bacterial cells fixed with 10% formaldehyde were subjected to a PCR analysis with
tox
gene-specific PCR primers. The resultant 112-nucleotide-long PCR product was sequenced using a dye terminator method, and an expected 57-nucleotide-long internal sequence of the
tox
gene was detected. This method is applicable for retrospective diagnosis in diphtheria cases in which only a formaldehyde-fixed clinical sample is available.
Epidemiologic Typing of
Salmonella enterica
Serotype Enteritidis in a Canada-Wide Outbreak of Gastroenteritis due to Contaminated Cheese
Authors: Ahmed Rafiq , Soule Geoff , Demczuk Walter H. , Clark Clifford , Khakhria Rasik , Ratnam Samuel , Marshall Stephen , Ng Lai-King , Woodward David L. , Johnson Wendy M. , Rodgers Frank G. 
Published: March 2020

ABSTRACT

A major Canada-wide outbreak of gastroenteritis due to
Salmonella enterica
serotype Enteritidis phage type (PT) 8 occurred in 1998, and this was traced to contaminated cheese in a commercial lunch pack product. Phage typing and pulsed-field gel electrophoresis linked the clinical and cheese isolates of serotype Enteritidis but failed to differentiate outbreak from nonoutbreak PT 8 strains. Further differentiation was made by biotyping based on melibiose fermentation.
Limitations of Vitek GPS-418 Cards in Exact Detection of Vancomycin-Resistant Enterococci with the
vanB
Genotype
Authors: Okabe Tadashi , Oana Kozue , Kawakami Yoshiyuki , Yamaguchi Masaru , Takahashi Yuko , Okimura Yukie , Honda Takayuki , Katsuyama Tsutomu 
Published: March 2020

ABSTRACT

The susceptibilities of 20 strains of vancomycin-resistant enterococci (VRE) with the
vanB
genotype obtained by using Vitek GPS-418 cards were compared with those obtained by the broth dilution method of the National Committee for Clinical Laboratory Standards (NCCLS) (approved standard M7-A4) and with those obtained by the agar screen method using bile esculin azide agar containing 6 μg of vancomycin per ml. Although both the broth dilution and agar screen methods disclosed no discordance, Vitek GPS-418 cards yielded a very major error compared with the results obtained by the reference broth dilution method of the NCCLS. Vitek GPS-418 cards were therefore found to have considerable room for improvement for the accurate detection of
vanB
VRE strains.