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J F Plouffe

Publications and source records attributed to J F Plouffe.

At least 55 records · Page 3Linked to original sources
PubMed1985

Difference in virulence of environmental isolates of Legionella pneumophila.

Endemic nosocomial Legionnaires disease has occurred at our medical center for several years. Two subtypes of Legionella pneumophila serogroup 1 (UH-1 and RH-1) have been isolated in approximately equal numbers from hospital potable water. However, almost all clinical isolates have been UH-1. To assess potential differences in virulence, 50% lethal doses (LD50) and 50% infective doses (ID50) of UH-1 and RH-1 were determined by intraperitoneal infection in guinea pigs. The UH-1 LD50 was 7.41 X 10(6) CFU, which was significantly lower than the RH-1 LD50 of 9.12 X 10(7) CFU (P = 0.0001). The mean time to death in UH-1-infected guinea pigs was also significantly shorter than in RH-1-infected animals (P = 0.0008). The UH-1 ID50 was 5.8 X 10(3) CFU, and although it was lower than the RH-1 ID50 of 1.4 X 10(4) CFU, this difference was not statistically significant (P = 0.21). This study demonstrates a difference in virulence between UH-1 and RH-1 in guinea pigs. Differences in strain virulence, as demonstrated between these two subtypes, may help to explain the widespread isolation of L. pneumophila from the environment contrasted with the limited occurrence of human Legionnaires disease.

Animals↗
PubMed1985

Serum bactericidal activity against Legionella pneumophila.

Two strains of Legionella pneumophila serogroup 1 (UH1 and RH1) were incubated in fresh human serum. The UH1 strain was serum resistant, whereas the RH1 strain was serum susceptible. The bactericidal activity of fresh serum was abrogated by heating. Serum resistance of L. pneumophila strains may correlate with increased virulence.

Blood Bactericidal Activity↗
PubMed1984

Serological differences in Legionella pneumophila infections.

Guinea pigs were infected with two subtypes of Legionella pneumophila serogroup 1 (UH1 and RH1). Seroconversion by indirect fluorescent-antibody assay was demonstrated in 94 to 97% of guinea pigs when the challenge strain was used as the antigen. The standard Philadelphia 1 antigen demonstrated seroconversion in 94% UH1-challenged animals, but in only 66% of RH1-challenged animals.

Animals↗
PubMed1983

Subtypes of Legionella pneumophila serogroup 1 associated with different attack rates.

From January, 1982, through February, 1983, 20 cases of nosocomial legionnaires' disease caused by Legionella pneumophila serogroup 1 were identified in two adjoining hospital buildings, UH and RH. Although the buildings housed similar patient populations and the hot water systems in each were colonised with similar numbers of L pneumophila serogroup 1, 19 cases (1.03/1000 discharges) occurred in UH and only 1 case (0.08/1000 discharges) occurred in RH. Three subtypes of L pneumophila serogroup 1 were defined by plasmid content and monoclonal antibody binding patterns; two were unique to the environmental and patient isolates from UH and one was unique to RH. The marked differences in the attack rates suggest that the UH subtypes may be more pathogenic than the RH subtype and that the subtyping of L pneumophila might be a useful tool for studying the epidemiology of legionnaires' disease.

Cross Infection↗
PubMed1983

Production of monoclonal antibodies to Legionella pneumophila serogroups 1 and 6.

To better define the surface antigens of Legionella pneumophila for clinical and experimental purposes, we have produced monoclonal antibodies to L. pneumophila serogroups 1 and 6. Two hybridomas were produced in serogroup 1. One antibody, LP-I-17, recognized a serogroup-common antigen. The second antibody, LP-I-81, was specific for serogroup 1. This antibody was able to agglutinate bacterial cells belonging to the serogroup 1 reference strains. Philadelphia and Knoxville. Microagglutination assays of environmental and clinical isolates revealed a subgroup of serogroup 1 environmental isolates which were not agglutinated by LP-I-81. This subset of isolates was segregated to certain buildings in the medical complex. Immunodiffusion studies showed identity between the LP-I-81 antigen and the serogroup-specific antigen of serogroup 1 organisms. This antigen could be absorbed out of the serogroup 1 organism extract with LP-I-81-coated Staphylococcus aureus, leaving the serogroup-common antigens. Three hybridomas were produced to serogroup 6. All three produced antibodies which were serogroup 6 specific and agglutinated serogroup 6 bacteria.

Agglutination Tests↗
PubMed1983

Plasmid profiles of clinical and environmental isolates of Legionella pneumophila serogroup 1.

Clinical and environmental Legionella pneumophila serogroup 1 isolates from a single water source in Columbus, Ohio, exhibited five different plasmid profiles. The multiplicity of plasmid profiles observed within a single geographic area and a skewed distribution of isolates bearing these plasmid profiles within this area suggest that plasmid analyses will be useful in the study of the epidemiology of Legionnaires disease and the environmental distribution of legionellae.

Bacterial Infections↗
PubMed1983

Cefotaxime: pharmacokinetics and in vitro antibacterial activity of serum and urine in normal human volunteers.

The pharmacokinetic and antibacterial properties of cefotaxime were determined in normal adult volunteers. Single doses of 250, 500, 1,000 and 2,000 mg were evaluated following 5- and 20-min intravenous (i.v.) infusions and intramuscular (i.m.) administration. Cefotaxime was well tolerated and mean peak serum levels exceeded the minimum inhibition concentration (MIC) values for a wide spectrum of potential bacterial pathogens. Approximately 48% of the i.v. doses was excreted renally; average volume of distribution was 30% of body weight and the t 1/2 was about 1 h. Cefotaxime was rapidly absorbed following i.m. injection with maximum serum concentrations occurring at approximately 0.6 h. Serum and urine antibacterial activity reflected the concentration of cefotaxime and MIC of the bacterial pathogens tested.

Bacteria↗
PubMed1982

Lymphocyte blastogenic responses to L. pneumophila in acute Legionellosis.

Thirteen patients with acute Legionellosis were studied. Acute serologic studies obtained within the first two weeks of illness were non-diagnostic in 10 of 13 cases. Lymphocyte blastogenic responses to sonicated L. pneumophila were much higher in patients with acute disease (mean net cpm +/- SEM = 66,786 +/- 15,428) than in subjects without a history of Legionellosis (11,800 +/- 1,760) p less than 0.01. Eleven of the 13 patients with acute Legionellosis had net cpm greater than 17,000. Lymphocytes from six patients with acute non-Legionnaires' pneumonia had mean cpm of 3,769 +/- 909 (p less than 0.01). Blastogenic response to L. pneumophila appears to occur earlier than the production of measurable antibody and may be a useful adjunct to diagnosis.

Adult↗
PubMed1982

Cord blood lymphocyte transformation responses to Legionella pneumophila.

Cord blood lymphocytes were obtained from 94 neonates for transformation assays with sonicated and partially Legionella antigens and phytohemagglutinin. The Legionella antigens gave mean stimulation indices (SI) of approximately three times the background. The nonspecific mitogen phytohemagglutinin gave mean SI of 23 times the background. There was some minor nonspecific stimulation of cord blood lymphocytes by Legionella antigens but not enough to account for the SI seen in patients with Legionnaires' disease (48 +/- 14).

Fetal Blood↗
PubMed1981

Treatment of Clostridium difficile colitis and diarrhea with vancomycin.

Toxigenic Clostridium difficle is the major cause of antibiotic-associated colitis and is susceptible to vancomycin at fecal concentrations achieved with oral therapy. The effect of oral vancomycin was studied in 16 patients with C. difficile-related diarrhea or colitis, 12 of whom had colitis documented by endoscopy, biopsy, and/or barium enema. Four patients had antibiotic-associated diarrhea and possibly antibiotic-associated colitis, because sigmoidoscopy either showed normal results (two patients) or was not performed (two patients). Nineteen episodes of diarrhea were treated with oral vancomycin in two dosage regimens for three to 14 days. Twelve patients received 2 g daily, and four patients initially received 1 g or less per day. Within 48 hours of the start of vancomycin therapy, 14 of 16 patients (87 percent) showed a decrease in temperature, abdominal pain and diarrhea. Diarrhea ceased completely within two days of the start of vancomycin in nine episodes, within three to seven days in six episodes, and within eight to 14 days in the remaining four episodes, and within eight to 14 days in the remaining four episodes. Diarrhea recurred in two of these patients (12 percent) when the drug inciting the initial episode of colitis was given again 42 days or more after vancomycin therapy was stopped; both patients responded again to retreatment with vancomycin. Oral vancomycin is an effective treatment of C. difficile-related colitis and diarrhea.

Adolescent↗
PubMed1981

Lymphocyte transformation to Legionella pneumophila.

Lymphocytes from seventeen subjects with previously diagnosed Legionnaires' disease and 63 subjects without a history of Legionellosis were studied in a transformation assay with a crude extract of Legionella pneumophila. In the lymphocyte transformation assay the mean stimulation index was 48+/-14 in the Legionnaires' disease group and 18+/-13 (p less than 0.001) in the control group. Endotoxin from Escherichia coli did not stimulate the cultures. Extracts from multiple other gram negative bacilli had minimal stimulation which was similar in lymphocytes from both groups. Lymphocytes from 2/3 of the subjects without a history of Legionellosis had increased incorporation of radionucleotide over background when incubated with the crude extract of L. pneumophila indicating that these subjects may have been exposed to L. pneumophila in the past and may be immune to Legionnaires' disease. This may help explain the very low attack rate (1.6-3.4%) in epidemics.

Antigens, Bacterial↗
PubMed1981

Lymphocyte cultures with small numbers of cells: antigenic stimulation by histoplasmin.

Previous experiments from this laboratory have shown that small numbers of lymphocytes could be stimulated by phytohemagglutinin to transform. Experiments in 15 subjects sensitized to histoplasmin demonstrated that antigenic stimulation with histoplasmin could be achieved with as few as 12.5 X 10(3) lymphocytes per 0.1 ml culture, (2,521 +/- 1.260) compared to unstimulated cultures (250 +/- 41), p less than 0.01, although false negative values (less than three fold increase in radionucleotide incorporation over unstimulated cultures) were obtained in 6 of 15 cases. Fourteen of 15 positive responders were correctly identified by culturing 25 X 10 (3) cells with histoplasmin for six days. The cell numbers required to give a blastogenic response with histoplasmin can be reduced to 25 X 10(3) cells in situations where cell availability is limited.

Antigens↗