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Isolation and partial characterization of polymyxin B-resistant isolates of Vibrio parahaemolyticus.

Two polymyxin-resistant isolates V2PXR and P1R4PXR of Vibrio parahaemolyticus were spontaneously isolated and compared with the polymyxin-sensitive strains as to their chemical compositions of cell envelopes and their outer membrane protein compositions. When grown in the presence or absence of polymyxin, the cell envelopes of polymyxin-resistant isolates showed a significantly increased content of protein as compared with those of respective polymyxin-sensitive strains. Both polymyxin-resistant isolates produced the major outer membrane protein b' after growth in the presence or absence of polymyxin. A new major outer membrane protein with an apparent molecular weight of 26,000 (26 K protein) was produced by polymyxin-resistant isolates grown in the presence of polymyxin. The production of 26 K protein was also observed in the polymyxin-resistant isolates grown in the medium containing low concentrations of NaCl (0.2% and 0.5%).

Anti-Bacterial Agents↗

The isolation, identification and molecular analysis of Candida spp. isolated from the oral cavities of patients with diabetes mellitus.

Previous studies have shown a high incidence (77%) of isolation of Candida spp. from the oral cavities of patients with type 1 diabetes mellitus. The aim of the present study was to assess the prevalence of yeast in the oral cavities of patients suffering from type 1 and type 2 diabetes mellitus. The patients were classified according to the level of diabetic control (HbA1c), and further stratified on the presence or absence of dental prosthesis. Oral rinse samples were assessed for the growth of yeast and the degree of colonization. Oral isolates were defined to the species level by both phenotypic and novel molecular methods. The overall proportion (60%) of diabetic patients who had Candida spp. isolated from the oral cavity was similar to that previously reported. Local oral factors, such as the presence of dentures, seemed to have a greater influence than diabetic status on the amount and species of Candida isolated from the oral cavities of diabetic patients. Diabetic patients with dentures had more non-albicans Candida isolated from their mouths than dentate diabetic patients. Candida dubliniensis was isolated from diabetic patients and may have a predilection for dentate patients.

Adult↗

Origin of reproductive isolation in the absence of apparent genic differentiation in a geographic isolate of Drosophila pseudoobscura.

F(1) males obtained from the cross of D. pseudoobscura females from Bogotá (Colombia) x males of this species from mainland, i.e. populations from various locations in the United States and from Guatemala, are sterile. This sterility is due to genes located on the X chromosome and the autosomes; the Y chromosome is not involved. The percentage of sterile males in backcrosses can be explained by assuming an interaction between two loci on the Bogotá X chromosome and probably two loci, one each on two of the mainland autosomes. The role of founder events, inbreeding and geographic isolation in the development of reproductive isolation and the magnitude of gene differences responsible for the origin of reproductive isolation is discussed. It is concluded that founder events, inbreeding and geographic isolation play a major role in the development of reproductive isolation and that major adaptive incorporation of new alleles at a large number of structural loci is not necessary for the origin of reproductive isolation.

Animals↗

Comparative in vitro activity of PGE 9262932 and fluoroquinolones against Canadian clinical Streptococcus pneumoniae isolates, including molecularly characterized ciprofloxacin-resistant isolates.

OBJECTIVES: The aim of this study was to assess the in vitro activity of the non-fluorinated quinolone PGE 9262932 against Streptococcus pneumoniae isolates with various resistance phenotypes: ciprofloxacin-resistant, macrolide-resistant, penicillin-resistant and trimethoprim/sulfamethoxazole-resistant. METHODS: The in vitro activity of PGE 9262932 against 2585 recent Canadian S. pneumoniae isolates with various resistance phenotypes was determined and compared with that of gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin. In particular, the activity of PGE 9262932 against ciprofloxacin-resistant isolates with defined parC and gyrA mutations was assessed. RESULTS: PGE 9262932 MIC90s were < or = 0.015 mg/L for all S. pneumoniae and 0.12 mg/L for the ciprofloxacin-resistant isolates. Resistance to penicillin, macrolides or trimethoprim/sulfamethoxazole had little effect on the PGE 9262932 MICs. The quinolone MIC50/90s were only slightly affected by the presence of one parC or gyrA mutation, but increased 2- to 16-fold in the presence of mutations in both parC and gyrA, depending on the specific quinolone. With each quinolone resistance genotype, the order of activity, based on MIC90, against the ciprofloxacin-resistant isolates was PGE 9262932, gemifloxacin, moxifloxacin, gatifloxacin and levofloxacin. CONCLUSIONS: PGE 9262932 was the most active quinolone against all S. pneumoniae isolates, regardless of resistance phenotype.

Anti-Bacterial Agents↗

Isolation and characterization of a new chimpanzee lentivirus (simian immunodeficiency virus isolate cpz-ant) from a wild-captured chimpanzee.

OBJECTIVE: To assess the prevalence of infection with simian immunodeficiency virus (SIV) isolate cpz, a lentivirus closely related to HIV-1, in chimpanzees, and to obtain new SIVcpz isolates. METHODS: Forty-four wild-captured chimpanzees in Belgium and Côte d'Ivoire were tested for HIV and SIV antibodies. Virus was isolated from the peripheral blood lymphocytes of positive animals and characterized by electron microscopy, Western blot and radioimmunoprecipitation assay. RESULTS: One animal had antibodies that cross-reacted with HIV-1. A lentivirus was isolated and referred to as SIVcpz-ant. With regard to molecular weight patterns, SIVcpz-ant differs from SIVcpz-gab' an HIV-1-related virus isolated from a wild-captured chimpanzee in Gabon. The major core protein, the transmembrane and outer membrane glycoproteins of the SIVcpz-ant strain consistently had higher molecular weights. Significantly more HIV-1-positive sera reacted with the envelope proteins of the Gabonese SIVcpz-gab strain than with the SIVcpz-ant strain. CONCLUSIONS: This study shows that natural infection of wild-captured chimpanzees with an HIV-related virus may not be uncommon. The diversity of the two chimpanzee isolates, the different geographical origin and the absence of disease suggest that chimpanzees have not recently become SIVcpz-infected.

Animals↗

Alteration of polymorphonuclear neutrophil surface receptor expression and migratory activity after isolation: comparison of whole blood and isolated PMN preparations from normal and postfracture trauma patients.

BACKGROUND: Post-traumatic MOF results from local tissue injury because of migration and activation of dysfunctional polymorphonuclear leukocytes (PMN). Although fracture surgery exacerbates the postinjury inflammatory response, it is usually beneficial. This study compared changes in PMN receptor expression and migratory activity, in whole blood and following PMN isolation. METHODS: IL-8 mediated PMN migration and expression of CXCR-1, CD11b, and CD18 was studied in isolated and whole blood PMN in normal controls. Migration was studied at admission and day 5 after surgery in trauma patients undergoing fracture surgery. RESULTS: PMN isolation results in increased expression of surface receptors and enhanced migration in normal controls. In trauma patient samples, isolated PMN migration is enhanced after injury, but suppressed when migration from whole blood is studied, both after injury and fracture surgery. CONCLUSION: PMN isolation results in priming for migration, which has a relatively greater impact upon PMN in trauma patients. The observation that PMN activity may decline but priming potential remains enhanced is novel. Further refinements of whole blood and isolated PMN techniques are clearly warranted. This may help to resolve the mismatch in clinical and scientific experience in those patients with major fractures requiring surgical stabilization.

Adult↗

Isolation of feline rotaviruses and their relationship to human and simian isolates by electropherotype and serotype.

Rotaviruses were detected by electron microscopy in the faecal specimens of six clinically well cats and virus was subsequently isolated from four of them. Analysis of the RNA of the isolates showed the existence of three electrophoretic types characteristic of the 'long' RNA electrophoretic pattern exhibited by rotaviruses. All feline isolates were neutralized only by antiserum to SA11 rotavirus, indicating that these isolates were serotype 3 rotaviruses. Antiserum prepared against a feline strain neutralized all the feline isolates as well as SA11 but showed no neutralizing activity against human isolates of serotype 1, 2 or 4.

Animals↗

A measles virus isolate from a child with Kawasaki disease: sequence comparison with contemporaneous isolates from 'classical' cases.

We examined the relationship between a measles virus isolate from a child with Kawasaki disease and two contemporaneous wild-type isolates from children with 'classical' measles and the Schwarz vaccine strain. Sequence analysis of 3118 bp from the nucleoprotein, matrix, fusion and haemagglutinin genes of each virus revealed that the isolate from the child with Kawasaki disease was not related to measles vaccine strains and did not contain any of the marked abnormalities previously found in subacute sclerosing panencephalitis isolates, but was more akin to wild-type isolates currently circulating in the U.K. A comparison of our sequences with those obtained from earlier wild-type U.K. isolates suggests significant evolution of measles virus in the U.K. over the last decade.

Amino Acid Sequence↗

DNA typing for Helicobacter pylori isolates from eradication-failed patients: comparison of the isolates before and after therapy.

BACKGROUND: Failure of Helicobacter pylori eradication occurs frequently despite use of multiple microbial agents. AIM: We aimed to study differences between H. pylori strains isolated before and after eradication failure. METHODS: We treated 87 patients with peptic ulcer using triple therapy consisting of omeprazole plus combinations of clarithromycin, amoxicillin, or metronidazole. We studied the status of cagA, vacA, and iceA by PCR, and examined the differences in H. pylori isolates by pulsed-field gel electrophoresis and arbitrary primer polymerase chain reaction. The minimum inhibitory concentration of clarithromycin, amoxicillin, or metronidazole was determined by an agar dilution method. RESULTS: Eradication therapy failed in 12 patients (14%); H. pylori isolates were obtained from all of these both before and after therapy. After eradication therapy, 10 patients were colonized with the same strain as before therapy, while the other two patients were colonized with different strains from those before therapy. In the former group, one isolate changed from metronidazole-sensitive to -resistant, one changed from clarithromycin- and metronidazole-sensitive to -resistant, and four were resistant to clarithromycin or metronidazole both before and after therapy. The other four isolates remained sensitive to clarithromycin and metronidazole after therapy. In the two patients who yielded apparently different isolates after therapy, they changed from clarithromycin- and metronidazole-sensitive to -resistant. CONCLUSION: Eradication of H. pylori by first-line therapy is an important goal in the treatment of H. pylori-positive peptic ulcer, and that appropriate antimicrobial sensitivity testing should be conducted in patients with eradication failure.

Adult↗

Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT009 isolates: differentiation of the live vaccine strain Zoosaloral from field isolates.

A total of 25 epidemiologically unrelated Salmonella enterica subsp. enterica (S.) serovar Typhimurium DT009 isolates from various human and animal sources, the original S. Typhimurium DT009 Zoosaloral live vaccine strain and two Zoosaloral strains reisolated from vaccinated chickens were investigated by various molecular typing methods (I) to determine the most suitable method or combination of methods for the differentiation of DT009 field isolates and (II) to investigate which molecular methods are suitable to differentiate the Zoosaloral live vaccine strain from field isolates of the same phage type. Based on the results of plasmid profile analysis, IS200 typing and macrorestriction analysis with XbaI, SpeI and BlnI, the 28 S. Typhimurium DT009 isolates were assigned to 16 different genomic groups, one of which was exclusively represented by the original and the reisolated Zoosaloral strains. IS200 typing was the most discriminatory single method for the differentiation of the DT009 isolates followed by plasmid profile analysis and BlnI-macrorestriction analysis. The Zoosaloral vaccine strain differed from the DT009 field isolates by its unique HindIII-fragment pattern of the virulence plasmid and by its unique SpeI-macrorestriction pattern.

Animals↗

Retrospective identification and characterization of Candida dubliniensis isolates among Candida albicans clinical laboratory isolates from human immunodeficiency virus (HIV)-infected and non-HIV-infected individuals.

Fungal opportunistic infections, and in particular those caused by the various Candida species, have gained considerable significance as a cause of morbidity and, often, mortality. The newly described species Candida dubliniensis phenotypically resembles Candida albicans so closely that it is easily misidentified as such. The present study was designed to determine the frequency at which this new species is not recognized in the clinical laboratory, to determine the patient populations with which C. dubliniensis is associated, to determine colonization versus infection frequency, and to assess fluconazole resistance. Over a 2-year period, 1,251 isolates that were initially identified as C. albicans by a hospital clinical laboratory were reevaluated for C. dubliniensis by inability to grow at 45 degrees C, colony color on CHROMagar Candida medium, coaggregation assay with Fusobacterium nucleatum, and sugar assimilation profiles (API 20C AUX yeast identification system). A total of 15 (1.2%) isolates from 12 patients were identified as C. dubliniensis. Ten of the patients were found to be immunocompromised (these included patients with human immunodeficiency virus infection or AIDS, cancer patients receiving chemotherapy, and patients awaiting transplantation). Thirteen isolates were highly susceptible to fluconazole (MIC, <0.5 microgram/ml). Three isolates from one patient, genotypically confirmed as the same strain, showed variable susceptibility to fluconazole. The first isolate was susceptible, whereas the other two isolates were dose-dependent susceptible (MIC, 16.0 microgram/ml). These data confirm the close association of C. dubliniensis with immunocompromised states and that increased fluconazole MICs may develop in vivo. This study emphasizes the importance of screening germ-tube-positive yeasts for the inability to grow at 45 degrees C followed by confirmatory tests in order to properly identify this species.

AIDS-Related Opportunistic Infections↗

Occurrence of extended-spectrum and AmpC beta-lactamases in bloodstream isolates of Klebsiella pneumoniae: isolates harbor plasmid-mediated FOX-5 and ACT-1 AmpC beta-lactamases.

We tested 190 Klebsiella pneumoniae bloodstream isolates recovered from 189 patients in 30 U.S. hospitals in 23 states to determine the occurrence of extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase producers. Based on growth inhibition by clavulanic acid by disk and MIC test methods, 18 (9.5%) of the isolates produced ESBLs. Although the disk diffusion method with standard breakpoints identified 28 cefoxitin-nonsusceptible isolates, only 5 (18%) of these were confirmed as AmpC producers. Of two AmpC confirmatory tests, the three-dimensional extract test was easier to perform than was the double-disk approximation test using a novel inhibitor, Syn2190. Three of the five AmpC producers carried the bla(FOX-5) gene, while the other two isolates harbored the bla(ACT-1) gene. All AmpC genes were transferable. In vitro susceptibility testing with standard inocula showed that all five AmpC-producing strains were susceptible to cefepime, imipenem, and ertapenem but that with a high inoculum, more of these strains were susceptible to the carbapenems than to cefepime. All but 1 of 14 screen-positive AmpC nonproducers (and ESBL nonproducers) were susceptible to ceftriaxone and cefepime at the standard inoculum as were 6 of 6 isolates that were randomly selected and tested with a high inoculum. These results indicate that (i). a significant number of K. pneumoniae bloodstream isolates harbor ESBL or AmpC beta-lactamases, (ii). confirmatory tests are necessary to identify true AmpC producers, and (iii). in vitro, carbapenems are active against AmpC-producing strains of K. pneumoniae.

Bacterial Proteins↗

Isolation of CD4-independent primary human immunodeficiency virus type 1 isolates that are syncytium inducing and acutely cytopathic for CD8+ lymphocytes.

Previous studies have established the existence of CD4-independent simian immunodeficiency virus, human immunodeficiency virus type 2 (HIV-2), and laboratory strains of HIV-1. However, whether CD4-independent viruses may also exist in HIV-1-infected patients has remained unclear. We have recently reported the isolation of viruses from an AIDS patient that were able to infect CD8(+) cells independent of CD4, using CD8 as a receptor. Using a similar approach, here we examined viruses from 12 randomly selected patients (obtained from the AIDS Research and Reference Program, National Institutes of Health) for the presence of CD4-independent HIV-1. CD4-independent variants were isolated from infected CD8(+) cells from the viral quasispecies of 7 of 12 patients. The CD4-independent isolates were able to infect primary CD8(+) cells as well as a CD4(-) CD8(+) T-cell line. Soluble CD4 and blocking anti-CD4 or -CD8 antibody had no effect on infection of CD8(+) cells. Remarkably, two of the seven CD4-independent isolates, but not their parental bulk viruses, induced syncytia and caused acute death of infected CD8(+) cells. Some of the CD4-independent variants were also able to infect U87 cells that were negative for CD4, CD8, and common HIV coreceptors, suggesting a novel entry mechanism for these isolates. The CD4-independent isolates were derived from adults and children infected with subtypes A, B, and D. Although no common motif for CD4 independence was found, novel sequence changes were observed in critical areas of the envelopes of the CD4-independent viruses. These results demonstrate that HIV-1-infected patients can frequently harbor viruses that are able to mediate CD4-independent infection of CD8(+) cells. In addition, this study also provides evidence of primary HIV-1 variants that are syncytium inducing and acutely cytopathic for CD8(+) lymphocytes.

Adult↗

Vasoconstrictive effects of endothelin-1, endothelin-3, and urotensin II in isolated perfused human lungs and isolated human pulmonary arteries.

BACKGROUND: Urotensin II (UII) has been identified as a ligand for the orphan receptor GPR14 through which it elicits potent vasoconstriction in humans and non-human primates. The pulmonary vasculature is particularly sensitive; human UII (hUII) exhibits a potency 28 times that of endothelin (ET)-1 in isolated pulmonary arteries obtained from cynomolgus monkeys. However, hUII induced vasoconstriction in isolated human intralobar pulmonary arteries is variable, possibly as a result of location dependent differences in receptor density or because it is only uncovered by disease dependent endothelial dysfunction. METHODS: The vasoactivity of both hUII and gobi UII (gUII) in comparison with ET-1 and ET-3 was studied in isolated perfused lung preparations (n = 14) and isolated intralobar pulmonary arteries (n = 40, mean diameter 548 (27) microm) obtained from 17 men of mean (SE) age 67 (2) years and eight women of mean (SE) age 65 (3) years with a variety of vascular diseases. RESULTS: ET-1 (10 pM-100 nM) and ET-3 (10 pM-30 nM) elicited vasoconstriction in the lung preparations, inducing comparable increases in pulmonary arterial pressure of 24.8 (4.5) mm Hg and 14.5 (4.9) mm Hg, respectively, at 30 nM (p = 0.13). Similarly, ET-1 (10 pM-300 nM) and ET-3 (10 pM-100 nM) caused marked vasoconstriction in isolated pulmonary arteries, inducing maximal changes in tension of 4.36 (0.26) mN/mm and 1.54 (0.44) mN/mm, respectively, generating -logEC(50) values of 7.67 (0.04) M and 8.08 (0.07) M, respectively (both p<0.05). However, neither hUII nor gUII (both 10 pM-1 micro M) had any vasoactive effect in either preparation. CONCLUSION: UII does not induce vasoconstriction in isolated human pulmonary arterial or lung preparations and is therefore unlikely to be involved in the control of pulmonary vascular tone.

Aged↗

Characterization of southern African isolates of maize streak virus: typing of three isolates by restriction mapping.

The genomic replicative form DNAs (RF-DNA) of three maize streak virus isolates (MSV-CT, MSV-PE, and MSV-SW) from widely separated locations in southern Africa were characterized by restriction endonuclease mapping in order to assess the feasibility of using the technique to determine genetic variability between isolates. The viruses were transmitted to and propagated in laboratory-grown maize by the leafhopper vector Cicadulina mbila (Naudé). MSV-PE produced more severe symptoms than MSV-CT and MSV-SW; the isolates were serologically identical in 'western' immunoblot tests, but distinct in 'sandwich' enzyme-linked immunosorbent assays. RF-DNA of all three isolates was prepared from infected maize; the RF-DNA of MSV-CT and MSV-PE was cloned in a plasmid vector in Escherichia coli. Restriction maps were generated from this cloned DNA and from the RF-DNA of MSV-SWA. The maps were similar in regions expected to be conserved, but there were also important differences between all isolates. The implications of these results, and of relationships amongst these and other sequenced isolates of MSV, are discussed.

Africa, Southern↗

High prevalence of penicillin resistance and comparative in vitro activity of various antibiotics in clinical isolates of streptococcus pneumoniae isolated in the Province of Hainaut during winter 2004.

A total of 154 isolates of Streptococcus pneumoniae obtained from 8 different centres in the province of Hainaut were included in this study. The susceptibilities to penicillin, amoxicillin, cefuroxime, ciprofloxacin, moxifloxacin, erythromycin and tetracycline were determined by a microdilution technique following NCCLS recommendations. Decreased susceptibility to penicillin was 32.5% (23.4% intermediate and 9.1% high-level). The other insusceptibility rates were as follows: amoxicillin 1.9% [0% Resistance (R)], cefuroxime 23.4% (R 22.1%), ciprofloxacin 9.1% (R 1.3%), erythromycin 39.6% (R 38.3%), and tetracycline 31.8% (R 30.5%). No decreased susceptibility was found for moxifloxacin. MICs of amoxicillin, cefuroxime, erythromycin and tetracycline rose with those of penicillin for penicillin-insusceptible isolates. Most penicillin-insusceptible isolates remained fully susceptible to amoxicillin (94%), while moxifloxacin and ciprofloxacin kept an activity on 100% and 92% of these isolates respectively. Phenotypes with triple or quadruple insusceptibility were present in 31.2% of the isolates. Penicillin-insusceptible isolates showed a co-insusceptibility of 36.7% to erythromycin, 30.0% to tetracycline and 3.3% to ciprofloxacin.

Adolescent↗

In vitro susceptibility of 21 antimicrobial agents to 37 isolates of Brachyspira hyodysenteriae isolated from pigs in Okinawa Prefecture.

The in vitro susceptibilities to 21 antimicrobial agents, of 37 isolates of Brachyspira (B.) hyodysenteriae isolated from pigs in Okinawa meat center and a pig farm in Okinawa Prefecture, Japan, were determined by the agar dilution method. Carbadox was the most active of all the agents tested against the isolates (MIC: <0.003 to 0.05). All the isolates were highly susceptible to olaquindox, tiamulin, dimetridazole, efrotomycin and valnemulin with MICs ranging from </=0.1 to 1.6 microg/ml. Penicillins, chloramphenicol, tetracyclines, terdecamycin and streptomycin were also active against the isolates. Most isolates were resistant to lincomycin, avilamycin and macrolides (with the exception of terdecamycin).

Animals↗

Isolation and characterization of an adventitious avian leukosis virus isolated from commercial Marek's disease vaccines.

Commercial Marek's disease (MD) vaccines produced by two manufacturers were tested for possible contamination with avian leukosis virus (ALV). Samples of MD vaccines manufactured by two companies (A and B) were received from a breeder company; samples were also received directly from vaccine company B. Using virus isolation tests, samples initially tested positive for subgroup E (endogenous) ALV. However, upon repassage, the vaccines also tested positive for exogenous ALV. The isolated exogenous ALV proved to be a subgroup A virus, as determined by flow cytometry using polyclonal chicken antibodies specific for various subgroups of ALV, and by DNA sequencing of the envelope glygoprotein (gp85). The exogenous ALV isolated from MD vaccines was inoculated in chickens from ADOL lines 15I(5) x 7(1) and 0 to determine its pathogenicity and compare it with that of Rous-associated-virus-1 (RAV-1), the prototype strain of ALV-A. Each chicken from each line was inoculated with approximately 10,000 infectious units of RAV-1 or the ALV-A isolated from vaccines termed B-39 virus at 7th day of embryonation. At hatch, and at 4, 8, and 16 wk of age, chickens were tested for viremia and cloacal shedding; chickens were also observed for ALV-induced tumors within 16 wk of age. Viremia and cloacal shedding results suggest that chickens from both lines were susceptible to infection with either virus. Within 16 wk of age, the proportion of ALV tumors induced by strain B-39 in line 0 and line 15I5 x 7(1) chickens was 0% and 12%, respectively, compared with 62% and 67% in chickens inoculated with RAV-1. The data indicate that commercial MD vaccines produced by two manufacturers were contaminated with endogenous subgroup E and an exogenous subgroup A ALV. Further, data from biological characterization suggest that the ALV-A isolated from commercial MD vaccines is of low oncogenicity, compared with that of RAV-1. GenBank accession numbers: The gp85 gene sequences of ALV isolated from commercial Marek's disease vaccines have been deposited in GenBank and assigned the following accession numbers: A46 subgroup A, DQ412726 ; B53 subgroup A, DQ412727; A46 subgroup E, DQ412728; B53 subgroup E, DQ412729.

Animals↗