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Biomedical subjects

J F John

Publications and source records attributed to J F John.

At least 55 records · Page 3Linked to original sources
PubMed1989

Molecular analysis of nosocomial epidemics.

Newer developments in molecular biology offer the hospital epidemiologist and clinical microbiologist powerful tools for analysis of nosocomial epidemics. Plasmid fingerprinting and genomic REA are rapid and often more definitive alternatives to serotyping and biotyping. Isolation of specific plasmids for special study involves more complicated manipulations. Polypeptide patterns, though at times diffuse in appearance, can be easily produced with SDS-PAGE of whole cells or outer membranes. Specific monoclonal antibodies as probes for individual proteins can generate more definitive answers about the exact type of protein(s) present. Multilocus enzyme electrophoresis (MLE) has become an ingenious tool for characterizing closely related nosocomial bacterial strains. The newest molecular methods using ribotyping, DNA probes, and the PCR will open many doors into the microbial genomes that were previously closed to the hospital microbial detective. These advances will compel hospitals to plan for their funding and implementation. Yet, like other scientific progress, the new biology in the nosocomial setting will raise as many questions as it will answer.

Bacteria↗
PubMed1988

Immunoblots, antimicrobial resistance, and bacteriophage typing of oxacillin-resistant Staphylococcus aureus.

An immunoblotting system was developed for typing of oxacillin-resistant Staphylococcus aureus. Clinical isolates recovered during a 40-month period at a single institution were evaluated with this typing scheme. Results were compared with susceptibility patterns and with bacteriophage typing results for 100 clinical isolates and with plasmid fingerprints for 14 isolates. Immunoblotting was found to be a useful method with good reproducibility that distinguished seven major groups of patient isolates that were clinically and epidemiologically related. Susceptibility patterns showed specific correlations with other typing results but were inferior to immunoblotting and phage typing for differentiating major groups of organisms. Plasmid profiles failed to distinguish two major groups that were readily identified by immunoblots and phage typing. There was evidence of increasing antimicrobial resistance of endemic hospital strains. Immunoblotting correlated well with phage typing, offered an alternative method for typing isolates that could not be typed by phage typing, and was superior to susceptibility testing and plasmid profiles for distinguishing different groups of oxacillin-resistant S. aureus at our institution.

Bacteriophage Typing↗
PubMed1988

An outbreak of Pseudomonas cepacia bacteremia associated with a contaminated intra-aortic balloon pump.

In January 1983, symptomatic Pseudomonas cepacia bacteremia developed in two patients in the cardiothoracic intensive care unit within 3 days after cardiac operation and insertion of an intra-aortic balloon pump. An epidemiologic and microbiologic investigation revealed that both patients required intra-aortic balloon pumping for circulatory support and that the water reservoir of the intra-aortic balloon pump (SMEC, Inc., Cookeville, Tenn.) contained more than 10(5) Pseudomonas cepacia per milliliter. This organism was also recovered from the purge button and on-off switch of the pump and from the hands of a health care worker who manipulated the water reservoir of the intra-aortic balloon pump. Agarose gel electrophoresis of lysates of Pseudomonas cepacia with rapid methods of deoxyribonucleic acid preparation revealed three identical plasmids of the Pseudomonas cepacia from the water reservoir of the intra-aortic balloon pump and from the infected patients. Transmission from the worker's hands to patients presumably occurred by inoculation of the intravascular lines during management. No additional cases of Pseudomonas cepacia bacteremia were observed after the unit was replaced with a nonwater reservior intra-aortic balloon pump. This report substantiates the ability of Pseudomonas cepacia to multiply in water and to cause epidemic bacteremia, identifies the water reservoir of the SMEC intra-aortic balloon pump as a previously unrecognized hazard for the patient requiring intra-aortic balloon pumping, and documents the value of plasmid analysis in elucidating the mode of transmission of nosocomial Pseudomonas cepacia infections.

Aged↗
PubMed1987

MRSA colonization.

Explore the source record for details and available documents.

Carrier State↗
PubMed1987

Protected transbronchial needle aspiration and protected specimen brush in the diagnosis of pneumonia.

Protected transbronchial needle aspiration (PTBNA) of pneumonic lung theoretically could bypass dislodged upper respiratory tract flora, a potential source of contamination of protected specimen brush (PSB) cultures. To evaluate the usefulness of PSB and PTBNA in establishing the etiology of pneumonia, we prospectively studied 20 patients with acute bacterial pneumonia not receiving antibiotics. After informed consent, patients had fiberoptic bronchoscopy under fluoroscopy to localize the pneumonia, and specimens were obtained by the PSB. The protective plug of a specially devised needle for PTBNA was pneumatically dislodged and aspiration was performed within the infiltrate under fluoroscopy. Quantitative cultures were plated immediately for aerobes, anaerobes, and Legionella. Greater than 4 X 10(3) organisms/brush or 1 X 10(4) organisms/ml needle aspirate were considered to be consistent with infection. The results using PSB and PTBNA were compared in 15 of 20 patients in whom a definitive diagnosis (positive blood or pleural fluid culture) or presumptive diagnosis (expectorated sputum culture, clinical characteristics, and response to specific therapy) was established. The PSB and PTBNA cultures on uninfected control subjects (n = 5) being bronchoscoped for other reasons were negative. The PSB and PTBNA were each diagnostic in 2 of the 5 patients with definitive diagnoses. In the group with a presumptive diagnosis (n = 10), PSB was diagnostic in 7 of 10 and PTBNA in 9 of 10. The overall (definitive plus presumptive) diagnostic yield was 60% for PSB and 73% for PTBNA. Multiple organisms were isolated in high concentrations in 53% of the patients. The most common organisms recovered in addition to the primary pathogen was alpha hemolytic streptococci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Gentamicin vs cefotaxime for therapy of neonatal sepsis. Relationship to drug resistance.

An outbreak of serious infections due to gentamicin-resistant Klebsiella pneumoniae occurred in a neonatal intensive care unit in which the combination of gentamicin sulfate and ampicillin sodium had been used for standard initial therapy for suspected sepsis for nearly 11 years. After institution of control measures that included the substitution of cefotaxime sodium for gentamicin in the standard regimen, the outbreak promptly subsided. Nevertheless, a second outbreak of serious infections due to cefotaxime-resistant Enterobacter cloacae began ten weeks later. Sequential stool cultures from patients in the unit confirmed the disappearance of gentamicin-resistant K pneumoniae and the emergence of cefotaxime-resistant E cloacae after the change in antibiotic policy. These observations suggest that routine use of newer cephalosporins for therapy of suspected sepsis may lead to the emergence of drug-resistant microorganisms more rapidly than has occurred with the aminoglycosides.

Ampicillin↗
PubMed1985

Effect of formulary restriction of cefotaxime usage.

Cefotaxime sodium was assigned to the open formulary for 12 months and then was placed on formulary restriction to evaluate the restriction's effect on rate of use by services and appropriateness of use. Over 18 months, 187 cases (72 before and 115 after restriction) were reviewed. The majority of use (prerestriction and postrestriction) was in the medicine, pediatrics, and surgery services. The postrestriction usage rate for the three services increased significantly. Cefotaxime was used appropriately in 85% of cases during both periods and was not used prophylactically. Appropriateness of use was independent of formulary restriction. During both periods, approximately 76% of patients received cefotaxime for pneumonia, sepsis, meningitis, or immunosuppression. Of 205 infections, gram-negative bacilli accounted for over half of the pathogens isolated. Thus, formulary restriction was ineffective in reducing the rate of cefotaxime usage and had no effect on the appropriateness of usage.

Adolescent↗
PubMed1984

Aminoglycoside resistance in Pseudomonas aeruginosa isolated from cystic fibrosis patients.

The authors studied 30 gentamicin-resistant and 17 gentamicin-sensitive strains of Pseudomonas aeruginosa isolated from respiratory cultures of patients with cystic fibrosis from five United States cities for the presence of plasmids, cross-resistance to other aminoglycosides, and the production of aminoglycoside-modifying enzymes. Four of 30 resistant strains and 3 of 17 sensitive strains contained one or more plasmids. Aminoglycoside cross-resistance to tobramycin, amikacin, and netilmicin was seen in 21 of 30 gentamicin-resistant strains. Seven strains that had low-level gentamicin resistance (minimum inhibitory concentrations [MIC] = 8-32 micrograms/mL) were sensitive to one or more of the other three aminoglycosides. Two strains with high-level gentamicin resistance (MIC greater than or equal to 128 micrograms/mL) were sensitive to amikacin. These two strains, each containing three plasmids, were the only isolates of nine tested that produced an aminoglycoside-modifying enzyme with activity against gentamicin. None of the plasmids was transferable by conjugation. Four strains, three of which contained one or more plasmids, produced an aminoglycoside 3'-0-phosphotransferase II. The authors propose that the mechanism of gentamicin resistance in P. aeruginosa from patients with cystic fibrosis is not commonly plasmid-mediated and likely is due to membrane impermeability to aminoglycosides.

Aminoglycosides↗
PubMed1984

Amifloxacin activity against well-defined gentamicin-resistant, gram-negative bacteria.

Amifloxacin (WIN 49375) activity against a well-defined group of gentamicin-resistant gram-negative bacilli was compared with the activity of 11 other antimicrobial agents. For all strains, amifloxacin and norfloxacin were the most active agents, followed by cefotaxime and moxalactam. For Acinetobacter sp. only amifloxacin had an achievable MIC for 90% of the strains. Amifloxacin joins other newly developed DNA gyrase inhibitors as potentially useful agents for infections due to aminoglycoside-resistant gram-negative bacilli.

Anti-Bacterial Agents↗
PubMed1984

Cytomegalovirus pneumonia in sickle cell disease.

Cytomegalovirus (CMV) pneumonia frequently occurs in immunocompromised hosts. Unlike encapsulated bacteria and Mycoplasma, CMV pneumonia has not been reported in sickle cell disease. We describe a case of a healthy young man with sickle cell thalassemia who died with CMV pneumonia.

Adolescent↗
PubMed1983

Cefotaxime therapy. Evaluation of its effect on bacterial meningitis, CSF drug levels, and bactericidal activity.

Cefotaxime sodium was evaluated in the treatment of ten patients with bacterial meningitis. Seven of the patients were infected with unusual and difficult to eradicate pathogens. Eight of the ten patients had a favorable clinical response and rapid sterilization of their CSF. Trough CSF levels of cefotaxime (range, 5.6 to 44.3 micrograms/mL) and desacetylcefotaxime (3.7 to 44.0 micrograms/mL) were manyfold greater than the minimal bactericidal concentrations of the causative pathogens with the exception of the one Pseudomonas aeruginosa isolate. Trough CSF bactericidal titers ranged from 1:16 to 1:4,096 or more (median, 1:256) in the nine patients with susceptible pathogens. Trough cefotaxime and desacetylcefotaxime levels and bactericidal titers were maintained or actually increased over the course of therapy. Cefotaxime appears to be a promising new agent for the treatment of bacterial meningitis.

Cefotaxime↗
PubMed1983

Molecular epidemiology of sequential nursery epidemics caused by multiresistant Klebsiella pneumoniae.

Multiresistant Klebsiella pneumoniae has been endemic among adult patients at Vanderbilt University Medical Center since 1973. Multiresistant K. pneumoniae was absent from pediatric wards until 1979, when it produced an epidemic in the intensive care nursery followed a year later by a second epidemic involving K. pneumoniae of the same serotype. The 105 megadalton (Md) conjugative resistance (R) plasmid (pCER7999) transferring multiple antibiotic resistance in the adult, endemic strain was found also in isolates from the first epidemic in the intensive care nursery. The mother of a child in the nursery harbored E. coli containing the same 105 Md R plasmid. The second epidemic also involved a 105 Md conjugative R plasmid, which, however, by molecular analysis was different from the first epidemic plasmid and also pCER7999. Thus, the second epidemic resulted from the introduction of a new, unrelated multiresistant K. pneumoniae strain. Contemporary hospital epidemiology often requires the application of molecular techniques for an understanding of nosocomial infections.

Cross Infection↗
PubMed1982

Cefotaxime therapy of serious bacterial infection in adults.

We evaluated the efficacy, safety, and tolerance of cefotaxime in 35 adults (25 with pleuropulmonary infections, 7 with genitourinary tract infections, and 3 with soft tissue infections). Of these 35 patients, 18 (51.4%) were seriously or critically ill. In vitro susceptibility testing revealed that 90.4% of the pathogens isolated were susceptible to cefotaxime (minimal inhibitory concentration, less than 8 micrograms/ml), 4.8% were intermediately susceptible (minimal inhibitory concentration, 8 to 32 micrograms/ml), and 4.8% were resistant (minimal inhibitory concentration, greater than 32 micrograms/ml). A total of 34 of the 35 patients (97%) were clinically and bacteriologically cured of their infections. Adverse reactions occurred in two patients, but these reactions did not require interruption of therapy.

Adolescent↗
PubMed1982

Evidence for a chromosomal site specifying amikacin resistance in multiresistant Serratia marcescens.

We studied 21 strains of amikacin-resistant Serratia marcescens from three different U.S. cities, Twenty of the 21 strains contained conjugative R plasmids mediating gentamicin and tobramycin resistance. Amikacin-resistant S. marcescens from two cities predominated in protracted outbreaks. Conversely, the amikacin-resistant Charleston strain (serotype 02/03:nonmotile) was isolated from only four patients during an outbreak of gentamicin- and tobramycin resistant, amikacin-susceptible S. marcescens (serotype O19:O17). Five different representative amikacin-resistant S. marcescens, each containing a single conjugative plasmid, elaborated a nontransferable aminoglycoside (6')-N-acetyltransferase [AAC(6')] with similar substrate profiles in addition to other transferable aminoglycoside-modifying enzymes. One amikacin-resistant S. marcescens cured of its plasmid and another naturally occurring plasmid-free amikacin-resistant S. marcescens elaborated only AAC(6')-1. These data support the concept of a chromosomal locus in S. marcescens for AAC(6')-1 which commonly coexists with plasmid-mediated genes for aminoglycoside-modifying enzymes.

Acetyltransferases↗