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Biomedical subjects

J H Jorgensen

Publications and source records attributed to J H Jorgensen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Development of an antimicrobial susceptibility testing method suitable for performance during space flight.

Very little is known regarding the effects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a space shuttle mission. Specially prepared susceptibility test research cards (bioMérieux Vitek, Hazelwood, Mo.) were designed to include 6 to 11 serial twofold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole. MICs of the drugs were determined by visual reading of color end points in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue; Accumed International, Westlake, Ohio). This study has demonstrated reproducible susceptibility results in the testing of isolates of Staphylococcus aureus, group A Streptococcus species, Enterococcus faecalis, Escherichia coli (beta-lactamase-positive and -negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa. In some instances, the MICs were comparable to those determined by a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the space shuttle, storage of inoculated cards at refrigeration temperature aboard the space shuttle until experiment initiation, and then incubation of the cards for 18 to 48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4 to 8 degrees C to accommodate the mission's time schedule and the astronaut's activities. For comparison, ground-based control (normal gravity) MIC values will be generated by simultaneous inoculation and incubation of a second set of test cards in a laboratory at the launch site. This procedure can provide for a safe and compact experiment that should yield new information on the effects of microgravity on the biological activities of various classes of antibiotics.

Aerospace Medicine↗
PubMed1996

Serogroup-specific epidemiology of Streptococcus pneumoniae: associations with age, sex, and geography in 7,000 episodes of invasive disease.

A study sample of 7,010 episodes of invasive Streptococcus pneumoniae disease was obtained by combining 13 existing datasets. Disease episodes due to each of 12 pneumococcal serogroups (1, 3-9, 14, 18, 19, and 23) were then compared with episodes in a constant internal control group to describe serogroup-specific variations in disease frequency by age, sex, and geographic origin. The results are presented as odds ratios (with 95% confidence intervals) derived by logistic regression, with adjustment for the major confounders, including dataset of origin. Variation in the male:female ratios between serogroups is small, suggesting that capsular characteristics are an unlikely explanation for the male preference of S. pneumoniae. Serogroups associated with higher nasopharyngeal prevalence (e.g., 19 and 24) are relatively more common in Europe and North American, while the invasive serotypes 1 and 5 are much more common in South America. The custom of reporting serogroup frequencies in two age groups, children and adults, conceals much of the variation in the age distributions across the whole span of life. The reduction of risk associated with serogroups 6, 14, 18, 19, and 23 beyond childhood follows different gradients, being most abrupt in serogroups 14 and most gradual in serogroup 18. The relative risk of disease with serotype 1 declines steadily throughout life, while with serotypes 3 and 8 it increases over middle age. Serogroups 7 and 23 are found unusually frequently in the third decade of life. Because of the wide differences in the epidemiology of individual serogroups of S. pneumoniae, it is questionable whether pneumococcal infection should continue to be classified as a single disease entity.

Adolescent↗
PubMed1996

In-vitro susceptibility of Streptococcus pneumoniae to the d- and l-isomers of ofloxacin: interpretive criteria and quality control limits.

The l-isomer of ofloxacin (levofloxacin) was twice as active as ofloxacin and the d-isomer was inactive against 654 Streptococcus pneumoniae isolates. For disc susceptibility tests of pneumococci, 5 micrograms levofloxacin discs can be used with interpretive criteria of < or = 12 mm for resistant (MIC > or = 8.0 mg/L) and > or = 16 mm for susceptible (MIC < or = 2.0 mg/L). For quality control of levofloxacin tests, S. pneumoniae ATCC 49619 should give zones 20-25 mm in diameter and MICs 0.5-2.0 mg/L.

Anti-Infective Agents↗
PubMed1996

In vivo activities of ceftriaxone and vancomycin against Borrelia spp. in the mouse brain and other sites.

Borrelia burgdorferi, the agent of Lyme disease, and B. turicatae, a neurotropic agent of relapsing fever, are susceptible to vancomycin in vitro, with an MIC of 0.5 microgram/ml. To determine the activity of vancomycin in vivo, particularly in the brain, we infected adult immunocompetent BALB/c and immunodeficient CB-17 scid mice with B. burgdorferi or B. turicatae. The mice were then treated with vancomycin, ceftriaxone as a positive control, or normal saline as a negative control. The effectiveness of treatment was assessed by cultures of blood and brain and other tissues. Ceftriaxone at a dose of 25 mg/kg of body weight administered every 12 h for 7 to 10 days eliminated cultivable B. burgdorferi or B. turicatae from all BALB/c or scid mice in the study. Vancomycin at 30 mg/kg administered every 12 h was effective in eliminating infection from immunodeficient mice if treatment was started within 3 days of the onset of infection. If treatment with vancomycin was delayed for 7 days or more, vancomycin failed to eradicate infection with B. burgdorferi or B. turicatae from immunodeficient mice. The failure of vancomycin in eradicating established infections in immunodeficient mice was associated with the persistence of viable spirochetes in the brain during antibiotic treatment.

Animals↗
PubMed1996

Development of interpretive criteria and quality control limits for macrolide and clindamycin susceptibility testing of Streptococcus pneumoniae.

A six-laboratory collaborative study was conducted to develop MIC and zone diameter quality control limits and interpretive criteria for antimicrobial susceptibility testing of Streptococcus pneumoniae with azithromycin, clarithromycin, dirithromycin, and clindamycin. The MICs of all of the agents plus erythromycin for 302 clinical isolates of pneumococci that had been selected with an emphasis on resistant strains were determined by use of the National Committee for Clinical Laboratory Standards (NCCLS)-recommended broth microdilution procedure. The zone diameters of the isolates were also determined for the same agents except erythromycin by the NCCLS disk diffusion test procedure. Repeated testing of S. pneumoniae ATCC 49619 with different sources and lots of media and disks allowed development of MIC and zone diameter quality control ranges for these agents. Interpretive criteria for the MIC of azithromycin were established and were as follows: susceptible, < or = 0.5 microgram/ml; intermediate, 1 microgram/ml; and resistant, > or = 2 micrograms/ml. The interpretive criteria advocated for the MICs of clarithromycin and clindamycin were as follows: susceptible, < or = 0.25 microgram/ml; intermediate, 0.5 microgram/ml; and resistant, > or = 1 microgram/ml. Comparison of MICs and disk diffusion zone diameters led to the development of interpretive criteria for the zone diameters for azithromycin, clarithromycin, and clindamycin that correlated well with these MIC breakpoints. Testing of this organism collection also led to the reestablishment of the erythromycin MIC breakpoints as being identical to those of clarithromycin, which resulted in equivalent cross-susceptibility and cross-resistance for the three macrolides that are currently marketed in the United States. Thus, the susceptibility of pneumococci to azithromycin and clarithromycin can be predicted accurately by testing only erythromycin in clinical laboratories. This recommendation, as well as the interpretive and quality control criteria that are described, have been accepted by NCCLS and are included in the latest NCCLS susceptibility testing guidelines.

Anti-Bacterial Agents↗
PubMed1996

Comparison of inoculation methods for testing enterococci by using vancomycin screening agar.

One hundred four recent clinical isolates of Enterococcus species were screened for vancomycin resistance by using inocula of 10(5) or 10(6) CFU dispensed by pipet and by use of a cotton swab dipped in a 0.5 McFarland standard organism suspension applied to the surface of brain heart infusion agar containing 6 micrograms of vancomycin per ml. The three inoculation methods were equivalent in the detection of nonsusceptible isolates. The use of swab inoculation was convenient and less costly than the use of micropipets.

Agar↗
PubMed1995

Tentative criteria for determining the in vitro susceptibilities of Haemophilus influenzae, including quality control parameters, to two fluoroquinolones (grepafloxacin and PD 131628).

Grepafloxacin (OPC 17116) and PD 131628 were evaluated against 150 Haemophilus influenzae isolates to propose susceptibility testing criteria for both broth dilution and disk diffusion procedures using haemophilus test medium. Grepafloxacin-susceptible isolates are defined as those for which minimum inhibitory concentrations (MICs) are < or = 0.06 micrograms/ml and zones of inhibition are > or = 27 mm. PD 131628-susceptible strains of H. influenzae included those that exhibited MICs < or = 0.03 micrograms/ml, and the zones were > or = 32 mm. All MICs were well below concentrations that can be achieved in the blood and tissues of patients treated with either study drug. Criteria for defining a resistant category cannot be determined until strains with elevated MICs are available for study. The proposed quality control guidelines for H. influenzae ATCC 49247 and the disk test are 32-39 mm in diameter for grepafloxacin and 34-42 mm for PD 131628. The preliminary broth microdilution MIC control limits for this strain are 0.002-0.016 micrograms/ml for grepafloxacin and 0.002-0.008 micrograms/ml for PD 131628.

Anti-Infective Agents↗
PubMed1995

Clinical and molecular epidemiology of vancomycin-resistant Enterococcus faecium during its emergence in a city in southern Texas.

During a 19-month period from April 1993 to October 1994, 41 isolates of vancomycin-resistant Enterococcus faecium (VREF) were detected in seven different hospitals in a city in southern Texas. A case-control study to determine the risk factors for acquisition was done in the hospital in which the majority of isolates were detected. Pulsed-field gel electrophoresis (PFGE) of whole-cell DNA was used to determine strain identity. Thirty-five (85%) of the 41 VREF isolates were of the vanB phenotype. Of these, 32 (91%) of 35 were the same strain by PFGE typing. The same vanB strain was documented in five different hospitals in the city. In contrast, 4 (67%) of 6 of the vanA phenotype VREF isolates were distinct strains by PFGE typing. Significant risk factors for colonization or infection with VREF were prior exposure to antibiotics (P = .04), the previous use of third-generation cephalosporins (P = .03), and the previous use of parenteral vancomycin (P = .002). Infection-control and antibiotic-utilization measures were implemented to control cross-transmission and selection of VREF isolates. During the emergence of VREF in our city, clonal dissemination of a single strain of vanB VREF among six hospitals was documented. Limited cross-transmission of vanA phenotype VREF isolates occurred, but most vanA VREF isolates were distinct strains selected in individual hospital environments.

Anti-Bacterial Agents↗
PubMed1995

Methicillin-resistant Staphylococcus aureus as a community organism.

An increase in methicillin-resistant Staphylococcus aureus (MRSA) infections prompted a study of MRSA during a 21-month period in a 600-bed university hospital in southern Texas. MRSA cases were classified as community, nosocomial, or transfer cases. A case-control study of risk factors for community MRSA compared with community methicillin-susceptible S. aureus (MSSA) was performed. Pulsed field gel electrophoresis (PFGE) of whole cell DNA typing was used as a marker of strain identity for 31 consecutive isolates collected during the last 8 months of the study. During the 21 months there were 170 patients with MRSA infection or colonization, an incidence of 0.2 per 1,000 patient-days. Ninety-nine (58%) of 170 isolates were from community cases; the community to nosocomial case ratio was 2:1. No significant risk factors differentiated patients with community MRSA compared with community MSSA. Most community MRSA isolates studied (15 [68%] of 22) had distinct PFGE patterns, as did many nosocomial MRSA isolates (4 [44%] of 9). MRSA isolates were commonly present on admission to the hospital, and multiple MRSA strains were demonstrated among both community and hospital isolates.

Adult↗
PubMed1995

The clinical and molecular epidemiology of bacteremias at a university hospital caused by pneumococci not susceptible to penicillin.

To determine the epidemiology of bacteremias due to pneumococci not susceptible to penicillin (PNSP) at a university hospital, active microbiologic surveillance of bacteremias due to PNSP was done for 28 months. Controls were bacteremias caused by penicillin-susceptible pneumococci. Antimicrobial susceptibilities for alternative antibiotics were determined. Pulsed-field gel electrophoresis (PFGE) and serotyping were used as markers of strain identity. Of 113 pneumococcal isolates, 14 (13%) were intermediate or resistant to penicillin (MIC > or = 0.1 microgram/mL). Twelve PNSP were resistant to other drugs: chloramphenicol (5), tetracycline (6), trimethoprim-sulfamethoxazole (5), cefotaxime (1), and erythromycin (1). Independently significant risk factors associated with PNSP bacteremia were sepsis and prior treatment with beta-lactam antibiotics. PFGE revealed 10 distinguishable patterns among 12 isolates available for typing. In general, PFGE typing correlated with serotyping. It also distinguished some isolates of the same serotype. PFGE typing and serotyping suggest that the frequency of PNSP in the San Antonio, Texas, area is not due to dissemination of a single clonal strain.

Adolescent↗
PubMed1995

Tests for susceptibility of Streptococcus pneumoniae to cefdinir: proposed interpretive criteria and quality control parameters for both microdilution and disc diffusion methods.

Proposed quality control (QC) parameters for susceptibility testing of Streptococcus pneumoniae to cefdinir were developed following the procedure recommended by the National Committee for Clinical Laboratory Standards. The proposed QC MIC range for microdilution susceptibility testing of S. pneumoniae ATCC 49619 is 0.06-0.25 mg/L. The proposed QC limits for inhibitory zone diameters of S. pneumoniae ATCC 49619 around 5 micrograms cefdinir disks is 26-31 mm. We recommend the following for tentative interpretive criteria for determining the susceptibility of S. pneumoniae to cefdinir: susceptible, MIC < or = 0.5 mg/L or inhibition zone diameter > or = 23 mm; intermediate, MIC 1.0 mg/L or inhibition zone, 20-22 mm; resistant, MIC > or = 2.0 mg/L or inhibition zone diameter, < or = 19 mm for broth microdilution and disc diffusion tests, respectively.

Cefdinir↗
PubMed1995

Interpretive criteria and quality control parameters for testing bacterial susceptibility to the fluoroquinolone PD131628.

For testing bacterial susceptibility to PD131628, a 5-micrograms disk and the following tentative interpretive criteria may be used: > or = 19 mm for susceptible (MIC, < or = 1.0 micrograms/ml), 16 to 18 mm for intermediate (MIC, 2.0 micrograms/ml), and < or = 15 mm for resistant (MIC, > or = 4.0 micrograms/ml). For standard quality control strains, the following limits are proposed: for Escherichia coli ATCC 25922, zones of 31 to 41 mm or a MIC of 0.002 to 0.016 micrograms/ml; for Pseudomonas aeruginosa ATCC 27853, zones of 26 to 34 mm or a MIC of 0.12 to 0.5 micrograms/ml; for Staphylococcus aureus ATCC 25923, zones of 27 to 33 mm; for Staphylococcus aureus ATCC 29213, a MIC of 0.03 to 0.12 micrograms/ml; and for Enterococcus faecalis ATCC 29212, a MIC of 0.12 to 0.5 micrograms/ml.

Anti-Infective Agents↗
PubMed1995

Molecular characterization and multilaboratory evaluation of Enterococcus faecalis ATCC 51299 for quality control of screening tests for vancomycin and high-level aminoglycoside resistance in enterococci.

Studies were conducted to validate the use of Enterococcus faecalis ATCC 51299 (which is vancomycin resistant and resistant to high levels of gentamicin and streptomycin) and E. faecalis ATCC 29212 (which is susceptible to vancomycin and against which gentamicin or streptomycin and cell wall-active agents have synergistic kill activity) as controls in an agar screening test for vancomycin resistance and high-level streptomycin and gentamicin resistance and a broth microdilution screening test for high-level streptomycin and gentamicin resistance. Both organisms performed as expected in these tests and will serve as appropriate controls. However, E. faecalis ATCC 29212 was occasionally noted to produce light growth on the vancomycin screening plate with certain lots of agar. Quality control ranges for disk diffusion tests with disks with large amounts of streptomycin (300 micrograms) and gentamicin (120 micrograms) were established for E. faecalis ATCC 29212; zone limits are 16 to 22 mm for gentamicin and 14 to 19 mm for streptomycin. No zones for inhibition were seen when E. faecalis ATCC 51299 was tested with these high-content disks.

Aminoglycosides↗
PubMed1995

Clinical isolates of Mycobacterium simiae in San Antonio, Texas. An 11-yr review.

During a period of 11 yr (1983-1993) 137 clinical isolates of Mycobacterium simiae obtained from 75 patients were identified in a University hospital in San Antonio, Texas. One hundred twenty-eight isolates (93%) were from a pulmonary source, four (3%) from blood, and five from other sites including skin, urine, lymph node, bone marrow, and brain. Of 62 evaluable patients, six (10%) had definite infection, nine (14%) had probable disease, and 48 (76%) were thought to be colonized. During the last 2 yr of the study (1992 and 1993), M. simiae became the second most frequently isolated nontuberculous mycobacterium at this institution surpassed only by Mycobacterium avium complex. There are limited data about effective treatment for this multidrug-resistant organism. New macrolides, quinolones, ethambutol, clofazimine, and aminoglycosides are promising therapeutic agents.

AIDS-Related Opportunistic Infections↗
PubMed1994

An old antibiotic for a new multiple-resistant Enterococcus faecium?

Enterococci have become an important cause of nosocomial infections and may demonstrate high-level resistance to multiple antibiotics. We present the case of a 68-year-old man with a history of small cell lung cancer, who developed bacteremia due to a strain of Enterococcus faecium. The isolate was resistant to multiple antibiotics including vancomycin, ampicillin, aminoglycosides, quinolones, and macrolides. The patient was successfully treated with doxycycline and removal of an infected central venous catheter.

Aged↗