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G Prats

Publications and source records attributed to G Prats.

At least 91 records · Page 5Linked to original sources
PubMed1993

Ultrastructural localization of major hydatid fluid antigens in brood capsules and protoscoleces of Echinococcus granulosus of human origin.

Monospecific rabbit antisera obtained through experimental immunization with previously purified proteins were used in the ultrastructural localization of two hydatid fluid antigens, in brood capsules and protoscoleces of Echinococcus granulosus of human origin. The antigen-antibody reaction was revealed by a colloidal gold based method. Reaction was evident in the connective region of the germinal membrane and in the parenchyma of the protoscoleces. Both antigen 5 and antigen B were located in the interstitial material between the parenchymal cells and precisely associated with disorganized areas. The brood capsule wall and the brood capsule contents, the tegument of the protoscoleces, the parenchymal cells, the muscle cells, the calcareous corpuscles and the hooks did not contain antigen 5 or antigen B. Label was not observed in the lumen of the collecting ducts or in the flame cells, although antigen 5 was evident in the periluminal cytoplasm. The origin of the antigens and their release are discussed.

Animals↗
PubMed1993

Detection of human papillomavirus 16 and 18 DNA in epithelial lesions of the lower genital tract by in situ hybridization and polymerase chain reaction: cervical scrapes are not substitutes for biopsies.

Human papillomavirus (HPV) types 16 and 18 in 66 women with histologically documented lesions of the genital tract and 64 control cohorts were investigated. The efficacies of in situ hybridization and polymerase chain reaction (PCR) in detecting HPV 16 and 18 DNA were analyzed. In order to assess the usefulness of replacing biopsies with cervical scrapes, the two samples were compared by PCR. The prevalence rates of HPV infection by PCR were 59.1 and 10.9% in patients and controls, respectively. PCR was three times more sensitive than in situ hybridization (52.6 versus 17.8%). However, the need to improve PCR sensitivity by subsequent dot blot hybridization reduced one of the main advantages of PCR, i.e., expeditious diagnosis. Cervical scrapes were less sensitive than biopsies (13.6 versus 53%), although with four (6.1%) patients with intraepithelial neoplasias, HPV DNA was identified only by means of cervical scraping. We conclude that obtaining biopsy specimens and cervical scraping are complementary sampling procedures.

Adolescent↗
PubMed1993

Infection of pulmonary artery catheters. Epidemiologic characteristics and multivariate analysis of risk factors.

Sixty-nine consecutive pulmonary artery catheters (PACs) were prospectively studied in a medical-surgical intensive care unit. Fifteen (21.7 percent) and two (2.9 percent) of the PACs were associated with colonization and bacteremia, respectively. These data represent an incidence of 4.98 and 0.66 episodes per 100 catheterization-days, respectively. Coagulase-negative staphylococci were the most common isolates. The source of the colonizing microorganism was the skin in 56 percent of cases, hubs in 28 percent, and unknown in 16 percent. From multivariate analysis, only more than 5 days of catheterization was significantly associated with a greater risk of colonization. Antimicrobial use was associated with negative cultures. The most useful method to diagnose colonization was the examination of both tip and intradermal segments. In addition, we suggest associate hub cultures when catheter-related bacteremia is suspected. These data may be useful in improving efficacy in the diagnosis and prevention of PAC-related infection.

Bacteremia↗
PubMed1993

A three-year study of severe community-acquired pneumonia with emphasis on outcome.

Fifty-eight consecutive patients with severe community-acquired pneumonia were studied prospectively during a three-year period. The group included 44 men and 14 women (mean age: 45.0 +/- 15.7 years). The cause of pneumonia was diagnosed in 35 (60.3 percent) cases, and the most common pathogens were Streptococcus pneumoniae (37.1 percent), Legionella pneumophila (22.8 percent) and Gram-negative bacilli (11.4 percent). The fact that Mycobacterium tuberculosis was present in four (11.4 percent) patients and Pneumocystis carinii in three (8.5 percent) is worthy of note. The overall death rate was 22.4 percent. More than 50 percent of deaths occurred within the first five days and were caused by septic shock, hemoptysis (tuberculosis) or hypoxia. However, hypoxia remains the main fatal complication and all late-occurring deaths (> 5 days) observed were due to this cause. These data could be important in planning strategies and protocols to improve prognosis.

Adult↗
PubMed1993

Impact of previous antimicrobial therapy on the etiology and outcome of ventilator-associated pneumonia.

OBJECTIVE: To define the influence of prior antibiotic use on the etiology and mortality of ventilator-associated pneumonia (VAP). SETTING: A university hospital medical-surgical ICU. DESIGN: Prospective clinical study. METHODS: Over a 35-month period, we prospectively studied 129 consecutive episodes of VAP. Etiologic diagnosis was established using a protected specimen brush and quantitative culture techniques. We examined prognostic factors by univariate and multivariate analyses using a statistical software package (SPSS). RESULTS: The rate of VAP caused by Gram-positive cocci or Haemophilus influenzae was statistically lower (p < 0.05) in the patients who had received antibiotics previously, while the rate of VAP caused by Pseudomonas aeruginosa was statistically higher (p < 0.01). Patients died of causes directly related to the infection in 18 (14.0 percent) episodes, P aeruginosa being isolated in 9 of these fatal cases. Indeed, we found that 27.7 percent (15/54) of patients who had received prior antimicrobial therapy before the onset of pneumonia died, compared with only 4.0 percent (3/75) of those who did not. In the univariate analysis, the variables significantly associated with attributable mortality were age older than 45 years, use of corticosteroids, presence of shock, hospital day of VAP over 9, antecedent COPD, and a prior antibiotic use. A step-forward logistic regression analysis defined only prior antibiotic use (p < 0.0001, OR = 9.2) as significantly influencing the risk of death from VAP. The same result was obtained when severity was included in the model. However, prior antibiotic use entirely dropped out as a significant risk factor when the etiologic agent was included in the regression equation. CONCLUSIONS: Distribution of infecting microorganisms responsible for VAP differs in patients who received prior antimicrobial therapy, and this factor determines a higher mortality rate. We suggest a restrictive antibiotic policy in mechanically ventilated patients with the purpose of reducing the risk of death from VAP.

Anti-Bacterial Agents↗
PubMed1992

Mycobacterium alvei sp. nov.

A new species of rapidly growing, nonphotochromogenic mycobacteria, Mycobacterium alvei, is described. The inclusion of this organism in the genus Mycobacterium is based on its acid fastness, its mycolate pattern, and its G + C content. A study of six strains showed that they form a homogeneous group with an internal phenotypic similarity value of 97 +/- 2.22%. DNA relatedness studies showed that the six M. alvei strains which we studied form a single DNA hybridization group which is less than 49% related to 14 other species of the genus Mycobacterium; the deltaTm values determined for the strains which exhibited higher levels of DNA homology were all greater than 7.9 degrees C. A lipid analysis showed that tuberculostearic acid was present. Docosanoic and tetracosanoic acid methyl esters were detected as mycolic acid cleavage products. All six isolates which we tested contained alpha-mycolic acids and relatively large amounts of a new kind of mycolic acid containing a methoxy group of omega-1 position, a characteristic that has not been described previously in mycobacteria. Strain CR-21 is the type strain; a culture of this strain has been deposited in the Collection Nationale de Cultures de Microorganismes de l'Institut Pasteur, Paris, France, as strain CIP 103464.

Base Composition↗
PubMed1992

Nosocomial respiratory tract infections in multiple trauma patients. Influence of level of consciousness with implications for therapy.

A prospective study of 161 multiple trauma patients was carried out to determine the incidence, the causative agents, and the outcome of nosocomial respiratory tract infections in this highly selected population. Thirty-eight (23.6 percent) patients developed a nosocomial pneumonia (NP). In addition, there were four superinfections in three patients, representing an incidence of 26 percent (42 of 161). Incidence of NP was significantly greater among comatose patients (42.2 vs 13.3 percent, p less than 0.05). Furthermore, purulent tracheobronchitis was diagnosed in six patients. The causative agent of NP was identified in 36 (85.7 percent) episodes by means of fiberoptic bronchoscopies with protected specimen brush sampling. Staphylococcus aureus (55.8 percent) was the predominant pathogen isolated in multiple trauma patients in coma (Glasgow coma score [GCS] below 9 during a period greater than 24 h), while aerobic Gram-negative bacilli were responsible for the majority of cases in the remaining population studied. The overall mortality rate was 19.8 percent, but only five deaths were related to NP. We conclude that nosocomial respiratory tract infections are a frequent problem in multiple trauma patients, especially in those with GCS below 9, although this complication is associated with a relatively low mortality. Among patients with GCS below 9, S aureus was a frequent finding; consequently, antimicrobial therapy in this population needs to be different than that for the remaining multiple trauma patients with NP.

Bacteria↗
PubMed1992

Pneumonia due to Haemophilus influenzae among mechanically ventilated patients. Incidence, outcome, and risk factors.

Incidence and potential risk factors for pneumonia due to Haemophilus influenzae in adults treated with mechanical ventilation in a medical-surgical ICU were investigated. Diagnosis was established in 91 episodes and H influenzae was isolated in 20 of them. Mean onset of ventilator-associated pneumonia (VAP) due to H influenzae was 10.8 days after intubation. Six patients with H influenzae VAP died in the ICU. Of 13 risk factors for developing VAP due to H influenzae, an absence of prior antibiotic treatment was the only variable which had statistical significance (p < 0.001). In these mechanically ventilated patients, Haemophilus influenzae was a common causative agent for VAP, frequently associated with Gram-positive cocci. Episodes of H influenzae VAP were associated with a lower mortality compared with other etiologies. The epidemiologic and clinical findings indicate that patients without a prior antimicrobial treatment have increased susceptibility to infections of the airway by H influenzae.

Adolescent↗
PubMed1992

[Septic shock: epidemiology and prognosis].

As part of an infection control program in ICU, we studied prospectively 1500 consecutive patients admitted to a medical and surgical ICU from January 1988 to July 1990. Over this period of time, 69 patients developed septic shock, and 38 of them died (55.1%). Primary source of infection was the lower respiratory tract or intraabdominal in more than 50% of cases, and were related to a high mortality rate, however SS arising from a biliary tract infection is associated with a mortality rate below 20%. In the univariate analysis, nosocomial origin (p = 0.0001), creatinine serum level > 175 mumol/l (p = 0.005), multiple organ failure in the first 24 hours after shock started (p = 0.02), underlying cancer disease (p = 0.02) or liver cirrhosis (p = 0.03) were associated with a statistically significant higher risk for dying. No differences were found regarding age, sex, admission date, coma, recent surgery, prior cardiac arrest, diabetes, organ transplantation, corticosteroid therapy, cancer chemotherapy, absence of fever, bacteriology of the infection and appropriate antibiotic therapy. The multivariate analysis further identified that creatinine serum level > 175 mumol/l (p = 0.004), underlying cancer disease (p = 0.005), liver cirrhosis (p = 0.02) and nosocomial-acquired infection (p = 0.02) were independently associated to a higher risk for dying. These data allows the identification of factors related to a worst outcome. The high mortality rates recorded for septic shock still recommends the rapid transfer of the patient to an ICU as well as the use of aggressive therapy in all cases.

Cross Infection↗
PubMed1992

Nosocomial pneumonia in critically ill comatose patients: need for a differential therapeutic approach.

The purpose of this prospective clinical study was to determine the incidence, bacteriology and outcome of lower respiratory tract infections developed among 208 consecutive, critically ill comatose patients, hospitalized in a university hospital, medical-surgical intensive care unit, over a three year period. Nosocomial pneumonia developed in 53 (25%) patients after a mean of 8.1 days (range 3-31 days). Furthermore, there were five superinfections, raising the mean incidence to 28%. One patient developed secondary bacteraemia, and another two had septic shock. Fifteen (28%) patients from the pneumonia group died, and six of these deaths were considered to be directly related to nosocomial pneumonia. Identification of the causative agent, using the protected specimen brush technique, was possible in 42 episodes; in 10 (24%) of these cases more than one microorganism was isolated. Gram-positive cocci represented 53% of isolates, and Staphylococcus aureus accounted for 78% of all Gram-positive cocci, being the most frequent microorganism in this population. In conclusion, nosocomial pneumonia is a common complication of critically ill comatose patients. Its characteristic aetiological spectrum in this population should affect antibiotic prescription. Consequently, we suggest including antimicrobial drugs which are active against S. aureus in the empirical regimen until aetiological diagnosis is established.

Anti-Bacterial Agents↗
PubMed1991

Echinococcus granulosus: antigen characterization by chemical treatment and enzymatic deglycosylation.

Parasite antigenic fractions obtained by biochemical purification of sheep hydatid fluid were subjected to enzymatic digestion. The relative mobilities of the 5 and B antigens, before and after treatment, were analyzed by polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. Antigenic fractions transferred to nitrocellulose were also treated with sodium metaperiodate and concanavalin A. The results indicate that antigen 5 contains a substantial amount of carbohydrates covalently linked to a polypeptide backbone, which strongly bind to concanavalin A and is removed by N-glycosidase F (PNGase F). Antigen 5 possesses complex N-linked oligosaccharides (PNGase F sensitive), without terminal N-acetyl-D-glucosamine residues (N-acetyl-D-glucosaminidase nonsensitive) and has no high-mannose oligosaccharides (endo-beta-N-acetylglucosaminidase H nonsensitive). In contrast, the antigen B of low molecular weight is not susceptible to either enzymatic digestions (PNGase F, Endo H, and N-acetyl-D-glucosaminidase) or sodium metaperiodate oxidation and it does not bind to concanavalin A. Polyclonal antibodies prepared against the two antigens reacted with the deglycosylated antigen 5 in Western blot. The dominant epitopes are, therefore, polypeptides, although the presence of carbohydrate epitopes in the native glycoproteins cannot be excluded.

Acetylglucosaminidase↗
PubMed1991

Distribution of a novel mycolic acid in species of the genus Mycobacterium.

We found that Mycobacterium porcinum ATCC 33776T (T = type strain) contains a new kind of mycolic acid with a methoxy group at the omega-1 position. This mycolic acid was identified by comparing it with the previously described methoxymycolic acids. The patterns of mycolic acid methyl esters from 418 strains belonging to 44 species of mycobacteria were studied by using thin-layer chromatography. In addition to M. procinum ATCC 33776T, representative strains of M. porcinum, Mycobacterium fortuitum, "Mycobacterium peregrinum," Mycobacterium senegalense, and a recently isolated Mycobacterium sp. contained appreciable amounts of the newly described mycolic acid.

Chromatography, Thin Layer↗
PubMed1991

Immunochemical localization of major hydatid fluid antigens in protoscoleces and cysts of Echinococcus granulosus from human origin.

Monospecific rabbit antisera obtained through experimental immunization with previously purified proteins were used in the structural localization of two hydatid fluid antigens, antigen 5 and antigen B, in cyst membranes and protoscoleces of E. granulosus from human origin. The antigen-antibody reaction was revealed by an avidin-biotin-peroxidase technique. Antigen 5 was not evident in the laminated membrane of the cyst wall, but it was associated with the germinal membrane of the cyst wall and brood capsules. The parenchyma of invaginated and evaginated protoscoleces was heavily labelled. The tegument, the calcareous corpuscles, the suckers and the hooks did not contain antigen 5. Degenerated protoscoleces were also labelled. Antigen B localization was essentially identical to antigen 5, but degenerated protoscoleces were not recognized by anti-antigen B antiserum. Technical aspects and differences with previously published work are discussed.

Animals↗
PubMed1991

Evaluation of practical chromatographic procedures for identification of clinical isolates of mycobacteria.

After experimental conditions were established, 366 strains of mycobacteria belonging to 23 different species were studied for fatty acids, secondary alcohols, and mycolic acid cleavage products by capillary gas-liquid chromatography. Additionally, the mycolic acid pattern was studied by thin-layer chromatography. Capillary gas-liquid chromatography allowed direct identification of the following Mycobacterium spp.: M. kansasii, M. marinum, M. szulgai, M. xenopi, M. malmoense, and M. gordonae. The patterns of mycolic acid methyl esters recorded for the test strains of M. chelonae and M. agri may be of value in the identification of these species. Moreover, the combined use of the two chromatographic techniques provided precise identification of the M. tuberculosis complex, M. simiae, M. fallax, M. triviale, and M. chelonae-like organisms. A minimal set of biochemical tests is usually required to obtain identification to the species level when chromatographic procedures alone are not sufficient. Under the reported experimental conditions, thin-layer chromatography and capillary gas-liquid chromatography are rapid and very useful techniques for the identification of mycobacteria.

Alcohols↗
PubMed1991

Incidence, etiology, and outcome of nosocomial pneumonia in mechanically ventilated patients.

This study assessed the incidence, etiology, and consequences of ventilator-associated pneumonia in 1,000 consecutive patients admitted in a medical-surgical intensive care unit (ICU). A total of 264 patients were submitted to mechanical ventilation (MV) for more than 48 hours. Fifty-eight (21.9 percent) patients developed a bacterial pneumonia after a mean of 7.9 days (range, 2 to 40 days) of MV. In addition, they were ten superinfections in nine patients, raising the mean incidence to 25.7 percent. Five patients developed secondary bacteremia, and another five had septic shock. Identification of the causative agent of pneumonia was possible in 47 episodes by means of highly specific techniques (telescoping plugged catheter, blood cultures, and/or necropsy). Thirteen (27.6 percent) of these cases were polymicrobial. The predominant pathogens isolated in the first episode of pneumonia were Gram-negative bacilli (62.6 percent), but a high incidence of Staphylococcus aureus infection (23.2 percent) was detected. Gram-negative bacilli represented 66.6 percent of the total organisms isolated in superinfections. The mortality rate in the pneumonia group was 42 percent; this percentage is similar to mortality rate among MV patients without pneumonia (37 percent). We conclude that nosocomial pneumonia is a frequent complication of MV in the medical-surgical ICU. Ventilator-associated pneumonia does not appear to increase fatality in critically ill patients with a high mortality rate (38 percent); however, it significantly prolongs the length of stay in the ICU for survivors.

Bacteria↗
PubMed1991

Laboratory diagnosis of catheter-related bacteremia.

Semiquantitative culture of the external surface of catheter tips has become the currently most used method to detect catheter colonisation and catheter-related bacteremia; however, this method may fail to detect significant colonisation of the internal lumen of catheters, and several quantitative methods have been described for this purpose. Although 15 and 1000 CFU are used to define positive catheters, the sensitivity and specificity are not yet well known, and the definitive cut-off level for a positive result remains to be established. We studied prospectively 91 intravascular catheter tips removed because a catheter-related infection was suspected. The result of external and internal cultures with different cut-off levels, alone or combined, were correlated with clinical data in 22 bacteremic episodes which occurred in these patients, 12 of which were catheter-related. The semiquantitative culture of the external surface alone with a cut-off level of 25 CFU provided the best means of detecting catheter-related bacteremia. This method has 100% sensitivity and 81.1% specificity. We conclude that semiquantitative culture technique of the catheter tip alone is sufficient and this method should be employed for diagnosing catheter-related bacteremia in unselected populations.

Bacteremia↗