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Biomedical subjects

H D Isenberg

Publications and source records attributed to H D Isenberg.

At least 37 records · Page 2Linked to original sources
PubMed1988

Central catheter infections: single- versus triple-lumen catheters. Influence of guide wires on infection rates when used for replacement of catheters.

A prospective study was conducted over six months to determine if triple-lumen catheters were associated with a higher rate of infection than single-lumen catheters. A total of 502 central intravascular catheters were prospectively collected from 362 consecutive patients in the adult intensive care units. Semiquantitative and broth cultures were performed on distal and proximal catheter segments, with peripheral blood culture specimens drawn in febrile patients. The overall infection rate for the 502 catheters was 11.8 percent or 2.2 infections per 100 days at risk. The infection rates were: single-lumen lines, 8 percent; triple-lumen lines, 32 percent; and triple-lumen pulmonary artery catheters, 12 percent. When corrected for time at risk, the triple-lumen lines and the triple-lumen pulmonary artery catheters had the same rate of infection, which was three times greater than that of the single-lumen catheters. After correction for confounding variables such as the presence of diabetes mellitus, the use of hyperalimentation, the degree of illness, dialysis, or ultrafiltration, and the use of a guide wire to place a replacement line over a pre-existing one, the risk of infection remained significantly higher for triple-lumen than for single-lumen catheters. The use of a guide wire to place a new line over an old one also was associated with a trend towards an increased risk of infection.

Adult↗
PubMed1988

Evaluation of three disinfectants after in-use stress.

Solutions of 2.0% and 3.4% glutaraldehyde, and of 0.5% phenate with 0.18% glutaraldehyde were stressed with a microbial and organic soil load for the periods advocated by the respective manufacturers. The disinfecting efficacy of the stressed solutions was challenged with Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Mycobacterium bovis (BCG), a water Mycobacterium sp. and Candida albicans. The three disinfectants were active against the fast-growing bacteria in appropriate dilutions; lesser dilutions of the glutaraldehyde solutions killed the mycobacteria and the yeast, while stressed phenate with glutaraldehyde did not. One hour exposure of the stressed disinfectants failed to kill the spore preparations while reducing the number of survivors.

Aldehydes↗
PubMed1988

Antimicrobial susceptibility testing: a critical evaluation.

Antibiotic susceptibility test results must be interpreted cautiously. There are important differences between the laboratory and natural environments. There are also important differences between disc and dilution tests, and between laboratories. Laboratory tests can demonstrate antagonism and synergy. Because beta-lactamases can be induced, beta-lactam susceptibility may have to be monitored during therapy. Increases in the incidence of drug resistance are particularly important in nosocomial infections.

Anti-Bacterial Agents↗
PubMed1988

Pathogenicity and virulence: another view.

The concepts of pathogenicity and virulence have governed our perception of microbial harmfulness since the time of Pasteur and Koch. These concepts resulted in the recognition and identification of numerous etiological agents and provided natural and synthetic agents effective in therapy and prevention of diseases. However, Koch's postulates--the premier product of this view--place the onus of harmfulness solely on the microbial world. Our recent experiences with polymicrobic and nosocomial infections, legionellosis, and acquired immunodeficiency syndrome point to the host as the major determinant of disease. The principles of parasitism, enunciated by Theobold Smith, approximate more accurately the disturbances of the host-parasite equilibrium we designate as infection. Many complex attributes of microbial anatomy and physiology have been obscured by our dependency on the pure-culture technique. For example, bacterial attachment organelles and the production of exopolysaccharides enable microorganisms to interact with mammalian glycocalyces and specific receptors. In addition, selection, through the use of therapeutic agents, aids in the progression of environmental organisms to members of the intimate human biosphere, with the potential to complicate the recovery of patients. These factors emphasize further the pivotal significance of host reactions in infections. Parasitism, in its negative aspects, explains the emergence of "new" infections that involve harm to more than host organs and cells: we may encounter subtler infections that reveal parasitic and host cell nucleic acid interactions in a form of genomic parasitism.

Animals↗
PubMed1988

Nosocomial urinary tract infection with a slowly growing, fastidious Escherichia coli.

Escherichia coli recovered from a nosocomially acquired urinary tract infection required 48 h of incubation on blood agar and did not grow on other routine clinical laboratory media. This bacterium dissociated readily into three colony types, all of which were confirmed as E. coli by DNA hybridization studies. Preliminary studies indicate a prolonged lag phase that could not be corrected by the addition of a variety of peptones and yeast extracts. Better growth was achieved by the addition of 10% horse serum.

Aged↗
PubMed1988

Comparison of three enzyme-linked immunosorbent assays and a direct fluorescent-antibody test for detection of respiratory syncytial virus antigen.

We prospectively evaluated three enzyme immunoassays (EIAs) and a direct fluorescent-antibody (DFA) test for respiratory syncytial virus detection. Of 90 specimens, 79% gave the same results in all four tests (30 positive and 41 negative) and 97% were in agreement in three of the four assays. The agreement between the direct fluorescent-antibody test and each enzyme immunoassay was greater than or equal to 86%.

Antigens, Viral↗
PubMed1988

Clinical laboratory challenges in the recognition of Leuconostoc spp.

Vancomycin-resistant Streptococcus salivarius-like bacteria were isolated from the blood and gastrostomy tube of a 6-month-old child during vancomycin therapy for Staphylococcus epidermidis central venous catheter-associated bacteremia. The isolates produced D-(-)-lactate and ethanol from glucose, hydrolyzed esculin, and produced no ammonia from arginine, thus fulfilling the major criteria as Leuconostoc spp. The enzymatic profile of the bacteria suggested that they were not lactobacilli or streptococci. Resistance to vancomycin and penicillin tolerance were noted. The formula fed through the gastrostomy tube was suspected as the vehicle that transmitted the organism to the patient. Penicillin and tobramycin therapy was used successfully.

Catheterization, Central Venous↗
PubMed1988

Microbiology of indwelling central intravascular catheters.

Indwelling central-line catheters (n = 502) from 362 patients in intensive care units were analyzed prospectively. The skin site, 6-cm-distal and -proximal subcutaneous segments of the catheter, exudates, and blood were cultured. Semiqualitative roll plate cultures of the catheter segments were followed by broth cultures and examined for 72 h. All isolates were identified, and susceptibilities were determined. Line infections, defined clinically, yielded 22 different microbial species; 10 different species were recovered from colonized lines. Of the Staphylococcus epidermidis isolates recovered, 39% occurred singly and 21% occurred in combination with other microorganisms; Enterococcus faecalis, S. hominis, and Pseudomonas aeruginosa were next in frequency of isolation. Line infections also yielded other staphylococci, viridans group streptococci, several members of the family Enterobacteriaceae, acinetobacters, anaerobic bacteria, Candida spp., and Aspergillus fumigatus. While S. epidermidis was also the most frequent isolate among the line colonizers, different species and different frequencies of isolation were found among this group. The study showed that the distal catheter segment broth culture was the best predictor of clinical line infections; in addition, gram-negative bacteria were isolated only from the catheters of patients with overt infections.

Bacteria↗
PubMed1988

Novel application of video image processing to biochemical and antimicrobial susceptibility testing.

ALADIN (Analytab Products, Plainview, N.Y.) is an automated instrument that uses video imaging (computer-assisted guided video camera) for the determination of biochemical and antimicrobial susceptibility test reactions. This collaborative investigation compared video-generated results obtained with ALADIN with visually determined findings. Both approaches were used to view identical reactions. Overall agreement for biochemical and antimicrobial susceptibility tests was greater than 95%. This study demonstrates that video imaging is an acceptable approach for determining microbial responses to biochemical and antimicrobial agents and may provide, with appropriate computer modifications, more accurate and reproducible results than are possible by visual scrutiny.

Bacteria, Anaerobic↗
PubMed1988

Odontogenic infection secondary to Leuconostoc species.

Leuconostoc species are gaining importance as pathogenic organisms. We present the first case of odontogenic infection caused by Leuconostoc spp. Isolates initially identified as streptococci were found to be vancomycin resistant. Rigorous bacteriologic investigation subsequently classified these organisms as Leuconostoc mesenteroides.

Bacterial Infections↗
PubMed1987

Collaborative clinical laboratory study of a broth-disk test for determination of bacterial susceptibility to beta-lactams in combination with amdinocillin.

Methodology for the performance of synergistic antibiotic susceptibility studies has not been standardized. We addressed this problem collaboratively with combinations of amdinocillin and select other beta-lactam antibiotics by using a simple broth-disk test compared with a microdilution approach. Each method used the same drugs singly and in combination. The broth-disk test evaluated each agent and the combinations at concentrations that reflected the breakpoints for each drug; the same ratios of beta-lactam to amdinocillin were used in doubling dilutions with the microdilution method. Initially, each participant studied the same 50 members of the family Enterobacteriaceae; each bacterium was studied on three occasions. Thereafter, 500 representatives of Enterobacteriaceae isolated recently from clinical specimens were studied. Designated strains served as controls. Reproducibility between the two approaches studied in phase 1 of the investigation indicated good agreement between the methods, ranging from 87 to 100%. Agreement between the microdilution and broth-disk tests for the 2,551 clinical isolates ranged from 86 to 95%, with slightly better correlations between combination results than with the single agents. The findings indicate that antibiotic disks used routinely in the clinical laboratory can be used in a simple elution test to determine susceptibility of organisms to beta-lactam antibiotics alone and in combination with amdinocillin.

Amdinocillin↗
PubMed1986

Acid-fast bacilli in sputum: a case of Legionella micdadei pneumonia.

Legionella micdadei has been implicated as a cause of nosocomial pneumonia. There are no reports of L. micdadei pneumonia diagnosed by acid-fast stain of expectorated sputum. We report a case of L. micdadei pneumonia in which expectorated sputum harbored acid-fast bacteria that reacted specifically with fluorescent antiserum to L. micdadei, confirmed by culture. In a patient at risk for nosocomial infection, the differential diagnosis of a positive sputum stain for acid-fast bacilli should include L. micdadei in addition to mycobacteria. Therapy for L. micdadei infection should be considered pending confirmation of the diagnosis.

Aged↗
PubMed1985

Collaborative evaluation of the UniScept qualitative antimicrobial susceptibility test.

The UniScept system (Analytab Products, Plainview, N.Y.) is a commercially prepared microdilution antimicrobial susceptibility test for the determination of qualitative susceptibility results for gram-negative and gram-positive bacteria. The system showed excellent correlation with the reference agar diffusion approach for organisms from clinical specimens and with stock and reference cultures. Intra- and interlaboratory reproducibility was high.

Anti-Bacterial Agents↗
PubMed1985

Clinical laboratory studies of disinfection with Sporicidin.

The clinical microbiology laboratory evaluation of disinfectants can serve as a guide for their application to reduce hospital-acquired infections. The use of Sporicidin, a glutaraldehyde-phenol formulation, was evaluated by the application of modified MIC and MBC determinations for standard organisms. In addition, the effect of this formulation on bacteria that may proliferate in water at ambient temperatures was studied. This investigation indicated that such studies can help the clinical microbiologist to guide the use of disinfectants and sterilants for the maintenance of a safe hospital environment.

Aldehydes↗