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Biomedical subjects

L G Burman

Publications and source records attributed to L G Burman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Zoned exponential, vertical and horizontal ultra-clean laminar airflows. No differences in bacteriological efficiency.

We compared the novel zoned exponential ultra-clean operating room ventilation, needing no extra side-walls with the traditionally used ultra-clean air systems having vertical or horizontal laminar airflow, but requiring extra side-walls. The three units were evaluated with regard to elimination of particles with focus on airborne and sedimenting bacteria-carrying particles (colony forming units, cfu) during rigidly standardized sham operations. Although minor differences were recorded inside the ultra-clean airflows, the three systems were comparable with regard to bacteriological efficiency and ensured a low air and surface contamination (0.05-4 cfu/m3 and 7-72 cfu/m2/h, depending on the site of sampling). We conclude that all three systems fulfilled well the criteria for ultra-clean air (< 10 cfu/m3), but that exponential airflow is the most versatile alternative, as additional side-walls around the operating area can be omitted.

Air Microbiology↗
PubMed1997

Transmission of urinary bacterial strains between patients with indwelling catheters--nursing in the same room and in separate rooms compared.

Despite lack of supporting scientific data it has been suggested that patients with an indwelling urinary catheter (IUC) should be nursed in separate rooms to reduce the risk of cross-infection. We conducted a one-month case-control study of nursing home patients with an IUC and bacteriuria, 20 nursed together pairwise and 20 in separate rooms, by weekly urine cultures and typing of the bacterial isolates. The transmission rate of urinary strains between patients was three times higher within rooms (5/9 possible transmissions) than between rooms (9/53 possible transmissions, P = 0.02). The study thus supported nursing IUC patients in separate rooms.

Aged↗
PubMed1997

An allelic variant of the chromosomal gene for class A beta-lactamase K2, specific for Klebsiella pneumoniae, is the ancestor of SHV-1.

Fecal Klebsiella isolates from neonates in 22 Swedish special care units were examined by a PCR we developed for detection of the SHV-1 beta-lactamase gene. All 105 K. pneumoniae isolates and all 11 K. pneumoniae reference strains (including the K. pneumoniae subsp. pneumoniae, ozaenae, and rhinoscleromatis type strains) tested were positive, whereas all 67 K. oxytoca isolates and the K. oxytoca, K. planticola, and K. terrigena type strains tested were negative. Resistance to beta-lactams in K. pneumoniae was not transferable by conjugation, and the beta-lactamase gene was never found on a plasmid. Southern blot analysis showed that the gene had a defined chromosomal location. Isoelectric focusing and sequencing of 231-bp PCR amplicons from different isolates revealed many variants of the enzyme, with the two main groups being SHV-1 like (pI 7.6; 68 isolates) and LEN-1 like (pI 7.1; 14 isolates). Clavulanic acid markedly reduced the MICs of ampicillin for all the K. pneumoniae isolates tested. This fact, MIC profiles (penicillin rather than cephalosporin resistance), pIs, and sequence data showed that the chromosomal beta-lactamase of K. pneumoniae is a class A, group 2 enzyme distinct from the chromosomal AmpC enzymes found in several other gram-negative bacteria and from the chromosomal beta-lactamase K1 of K. oxytoca. We propose that the chromosomal beta-lactamase of K. pneumoniae be designated K2 and suggest that an allelic pI 7.6 variant of this enzyme is the ancestor of the SHV family of plasmid-mediated beta-lactamases.

Alleles↗
PubMed1997

Cytokine gene expression during experimental Escherichia coli pyelonephritis in mice.

PURPOSE: We studied nine inflammatory and immunoregulatory cytokines in acute pyelonephritis and urethral obstruction in mice to better understand the processes underlying kidney inflammation and scarring. MATERIALS AND METHODS: Experimental acute pyelonephritis was established in Bki NMRI outbred mice by bladder inoculation of Escherichia coli, followed by 6 h urethral obstruction. The numbers of cytokine mRNA expressing cells for interleukin-1 (IL-1), IL-4, IL-6, IL-10, IL-12, tumor necrosis factor alpha (TNF-alpha), TNF-beta, transforming growth factor beta (TGF-beta) and interferon gamma (IFN-gamma) were determined in the kidneys and spleens from the infected, non-infected but obstructed and untouched mice using in situ hybridization with radio-labelled oligonucleotide probes at 12 h, 48 h and 6 d after release of the urethral obstruction. RESULTS: Kidney cell expression of IL-1, IL-6 and TNF-alpha mRNA was observed already at 12 h and persisted on day 6 in the infected animals. A significant proinflammatory cytokine response occurred also in the non-infected obstructed animals, albeit later and at lower levels. A marked increase of IL-4, IL-10, TGF-beta and IFN-gamma mRNA producing cells was also found in the kidneys of these two groups again with higher levels in the infected animals. Very high numbers of splenocytes expressing mRNA for IL-1 were observed especially in the infected animals. A high proportion of splenocytes further expressed mRNA for IL-6, TNF-alpha, IL-4, IL-10, IFN-gamma and TGF-beta, again with highest numbers in the infected group of animals. CONCLUSIONS: The present study extends previous knowledge about the local and systemic cytokine expression profiles during acute pyelonephritis and after urethral obstruction. Of particular interest was the marked kidney cell expression of mRNA for TGF-beta, presumed to be important both for obstructive and post-infectious renal scarring.

Acute Disease↗
PubMed1996

Elevated cytokine levels in tracheobronchial aspirate fluids from ventilator treated neonates with bronchopulmonary dysplasia.

UNLABELLED: Bronchopulmonary dysplasia (BPD) is a chronic lung disease often occurring in ventilator-treated very low birth weight infants. The aetiology of BPD is multifactorial and pulmonary immaturity, high oxygen concentrations, peak inspiratory pressure levels and large tidal volumes during prolonged mechanical ventilation are important factors. We measured in tracheobronchial aspirate fluid (TAF) the concentrations of the pro-inflammatory cytokines tumour necrosis factor alpha, interleukin-1 beta (IL-1 beta), IL-6, IL-8, and IL-1 receptor antagonist in infants requiring artificial ventilation for BPD (n = 17) or respiratory distress syndrome (RDS) (n = 15) or postoperatively after surgery (n = 15). The median levels of all studied cytokines in TAF were higher in infants with BPD without local or systemic corticosteroid treatment compared to the median TAF levels of BPD neonates treated with corticosteroids (P = 0.06-P < 0.01). The neonates with BPD not treated with corticosteroids also showed higher levels of the five studied cytokines in TAF compared to infants on short-time ventilator treatment (P < 0.01-P < 0.001) and compared to neonates with RDS (P = 0.07-P < 0.001). The corticosteroid treated neonates with BPD had TAF cytokine levels approaching those of the control neonates. CONCLUSION: Tumour necrosis factors alpha, IL-1 beta, IL6, IL8 and IL1ra were markedly elevated in tracheobronchial aspirate fluids from neonates with bronchopulmonary dysplasia. Corticoid treatment seemed to reduce these levels.

Body Fluids↗
PubMed1996

Interleukin-1 alpha and interleukin-6 in the urine, kidney, and bladder of mice inoculated with Escherichia coli.

After bladder inoculation of mice using the pyelonephritogenic Escherichia coli strain DS17, urinary interleukin-1 alpha (IL-1 alpha) peaked at 0.5 h post infection (mean 233 pg/ml), interleukin-6 (IL-6) at 2 h (mean 572 pg/ml), and leukocyturia at 4 h, all three persisting for more than 24 h. In the kidneys IL-1 alpha peaked at 2 h, persisted over 24 h (mean 900-1,000 pg/ml), and decreased over 2-6 days post inoculation to a mean value of 208 pg/ml. Control kidneys showed low IL-1 alpha values. IL-6 in the kidneys peaked at 5 h (mean 9,999 pg/ml) but normalized, i.e., similar to control kidneys, by 48 h (mean 105 pg/ml). A similar cytokine response, but with tenfold lower levels, was found in the bladder tissue. The isogenic P-negative E. coli mutant DS178 elicited lower IL-6 in the kidneys at 5 h, but persisted in higher numbers in the kidneys at 6 days. Bacterial counts and cytokine levels correlated both in the kidneys and in bladder tissue, (r = 0.50-0.76, P < 0.001). Characterization of the immune response gives a better understanding of the relative importance of different bacterial characteristics for the local inflammatory process and is needed for studies of its pharmacological down-regulation.

Animals↗
PubMed1996

Inefficiency of upward displacement operating theatre ventilation.

A new thermally based ventilation system ('Floormaster') with inlet of cool clean air at floor level, and evacuation at the ceiling of the air warmed by activity in the room (upward displacement ventilation, 17 air changes/h) was compared with a standard positive pressure (plenum) ventilation system with air supply through an inclined perforated screen along one wall at the ceiling and evacuation at floor level (conventional turbulent or mixing system, 16 air changes/h). The study was made during rigidly standardized sham operations (N = 20) performed in the same operating room by a six-member team wearing non-woven disposable or cotton clothing. In general the upward displacement system removed dust particles too small to carry bacteria (0.16-<0.3 microm, 0.001<P<0.01) more efficiently than the conventional system. However, the displacement system also yielded two to threefold higher air and surface bacterial counts in areas important for surgical asepsis (wound area, instrument table) especially with regard to bacterial sedimentation (0.001<P<0.05). The major shortcoming of the displacement system was insufficient elimination of the larger bacteria-carrying particles. The type of clothing worn by the members of the team did not influence the overall results. We conclude that an upward displacement system will lead to increased counts of airborne and sedimenting bacteria and thus increase the risk of postoperative infection in comparison with conventional operating room ventilation systems.

Air Microbiology↗
PubMed1996

Interleukin-1 alpha and interleukin-1 receptor antagonist in the urine of children with acute pyelonephritis and relation to renal scarring.

Urinary concentrations of interleukin-1 alpha (IL-1 alpha) and interleukin-1 receptor antagonist (IL-lra) standardized to urinary creatinine concentrations were studied. The median standardized IL-1 alpha creatinine quotient in children with first-time acute pyelonephritis was 3.6 pg/mumol, but was nondetectable in children with recurrent pyelonephritis, children with non-renal febrile conditions and children convalescent after acute pyelonephritis (p < 0.05-0.01). IL-lra levels were also significantly higher in children with acute first-time pyelonephritis (median of 239 pg/mumol) compared to these three groups of children (p < 0.01-0.001). The highest urinary IL-lra levels, however, were found in the healthy controls (median value 1.019; p < 0.001). Both cytokines were higher among children younger than one year compared to older children. The acute IL-1 alpha creatinine quotients were lowest in children with uptake defects on 99mTC-dimercaptosuccinic acid (DMSA) scintigraphy both during the acute infection (reflecting the acute inflammation) (p < 0.001) and 1 year after the acute infection (reflecting permanent kidney scarring) (p < 0.001). In conclusion, persisting high urinary levels of IL-1 alpha were associated with less renal inflammation and scarring.

Acute Disease↗
PubMed1996

A hospital outbreak of high-level beta-lactam-resistant Enterobacter spp.: association more with ampicillin and cephalosporin therapy than with nosocomial transmission.

We studied an 8 month outbreak of a 7-fold increased isolation rate of high-level beta-lactam-resistant Enterobacter spp. from clinical infections (20 patients, 22 isolates: 20 E. cloacae, 2 E. aerogenes). In a case-control analysis the occurrence of resistant Enterobacter spp. was found to be associated with treatment with multiple antibiotics (p = 0.03), broad-spectrum beta-lactam agents (p = 0.0001) including ampicillin (p = 0.04), and cephalosporins (cefuroxime and cefotaxime, p = 0.004). Biochemical fingerprinting and pulsed-field gel electrophoresis (PFGE) typing showed no identity between the resistant isolates, indicating that neither cross-infection nor nosocomial transmission from a common source was the immediate cause of the problem. The outbreak was not paralleled by the overall Enterobacter spp. isolation rate or the antibiotic usage pattern in the hospital. Thus, the underlying cause of the outbreak remained obscure.

Aged↗
PubMed1996

Zoned vertical ultraclean operating room ventilation. A novel concept making long side walls unnecessary.

We evaluated a novel concept of High Efficiency Particulate Air (HEPA)-filtered vertical Laminar Air Flow (LAF) for operating room ventilation, designed to be used without side-walls. The LAF-unit has a central zone with an airflow of 0.4 m/s and a peripheral zone with an airflow of 0.2 m/s. The design provides an exponential downflow of air resembling an upside-down trumpet mouth and it was claimed to prevent entrainment of peripheral contaminated air. The unit was evaluated with regard to elimination of particles with focus on bacteria-carrying particles (colony-forming units = cfu) during rigidly standardized sham operations. Three different lengths of walls/enclosures (short-ending 2.0 m, medium 1.0 m and long 0.2 m above the floor) were tested. It provided a high degree of bacteriological cleanliness (0.05-4 cfu/m3 of air and 7-64 cfu/m2/h surface contamination) and its efficiency was proved to be independent of the length of the enclosures. We conclude that the novel zoned ultraclean vertical LAF unit is versatile, as it allows for omitting long side-walls, without compromising bacteriological safety.

Air Microbiology↗
PubMed1995

Survival on skin and surfaces of epidemic and non-epidemic strains of enterobacteria from neonatal special care units.

It has been suggested that increased ability to survive on the hands of hospital staff contributes to transmission of certain strains of Gram-negative bacteria. We tested this hypothesis by comparing the survival on fingertips, glass slides and membrane filters of epidemic (M, major) and matched non-epidemic (S, sporadic) faecal strains of Escherichia coli (n = 13 vs. 13) and Klebsiella spp. (n = 19 vs. 19) found among 1066 neonates in 25 special care units (SCUs). The time to 50% killing at 22 degrees C in air was longer for E. coli than for Klebsiella spp. both on human skin (median 6 vs. 2 min P < 0.001) and glass surfaces (15 vs. 8 min P < 0.001). On the other hand, Klebsiella spp. were superior to E. coli in long-term survival tests on membrane filters expressed as the minimum inoculum still yielding growth after 10 days exposure at 22 degrees C in air (10(5) vs. 10(8) bacteria P < 0.001). Despite a large variation in survival times between individual strains no differences between M strains and S strains were observed in any of the three tests. This indicates that bacterial properties other than survival on surfaces contribute to the increased capacity for transmission of certain strains of enterobacteria in SCUs.

Adult↗
PubMed1995

Correlation between susceptibility of infants to infections and interaction with neutrophils of Escherichia coli strains causing neonatal and infantile septicemia.

The ability of Escherichia coli strains causing invasive infections to associate to human neutrophils and induce oxygen radicals was studied in three groups of blood isolates from neonates and infants: low-virulence septicemia strains (LVS), normal septicemia strains (NS), and meningitis strains (M). Infants were classified by susceptibility to infection as low- (LR) or high-risk (HR). All LVS strains were isolated from HR infants and showed higher association to neutrophils (P < .05) and induced a higher oxidative response (P < .05) compared with that of NS and M strains from LR infants. Three LVS strains caused the cells to release oxidative metabolites extracellularly. Thus, impaired interaction with neutrophils is characteristic of virulent clones of E. coli capable of causing invasive infection in healthy full-term neonates. Furthermore, increased extracellular release of oxygen metabolites could harm the surrounding tissue and potentiate the inflammatory process.

Bacteremia↗
PubMed1995

Biochemical fingerprinting compared with ribotyping and pulsed-field gel electrophoresis of DNA for epidemiological typing of enterococci.

The Phene Plate (PhP) biochemical fingerprinting system for bacteria is based on measurements of the kinetics of bacterial biochemical reactions. This system was modified for typing of enterococci and was compared with DNA typing by pulsed-field gel electrophoresis and with ribotyping by using 45 Enterococcus faecalis isolates from international collections. It was also used to study 170 fecal enterococcal isolates from healthy individuals and 28 isolates of E. faecalis from the blood of neonates. The PhP system showed a high degree of discriminatory power for unrelated enterococcal isolates. Among the 170 unrelated fecal isolates, 107 isolates from international collections, PhP typing discriminated 19 types, and ribotyping discriminated 5 types. In most cases, when isolates were of the same DNA type, they were also of the same PhP type, and the level of agreement between these two methods was high (96%). A combination of PhP typing and DNA typing identified 34 different types, but ribotyping did not yield any further discrimination. PhP typing of E. faecalis isolates from healthy individuals (n = 89) and from the blood of neonates with septicemia (n = 28) yielded a diversity of 0.93 for both populations and similar major PhP types in both populations. Thus, the isolates from blood seemed to consist of a normal E. faecalis population, without a dominance of certain strains associated with virulence. We conclude that the PhP system is useful for epidemiological studies of enterococcal isolates, yielding results similar to those obtained with DNA typing by pulsed-field gel electrophoresis. Since PhP typing is a method that is simple and rapid and that is based on automatic evaluation of the data, it is suitable for analyzing large numbers of isolates and can be used alone or in combination with DNA typing or epidemiological and ecological studies of enterococci.

Bacterial Typing Techniques↗
PubMed1994

Interleukin-6 and interleukin-8 in the urine of children with acute pyelonephritis.

Interleukin-6 (IL-6) and interleukin-8 (IL-8) are important mediators of the inflammatory response in serious bacterial infections. We studied the levels of these two cytokines (standardised for urinary creatinine) in the urine of infants and children during and 6 weeks after acute pyelonephritis and in non-renal febrile controls and healthy children without apparent infection. IL-6 was detected in the urine of 52% of children with pyelonephritis compared with 15% of other children (P < 0.001). The median urinary IL-6 level in acute pyelonephritis was 4 pg/mumol compared with undetectable levels in the control group (P < 0.001). IL-8 was detected in 98% of children with pyelonephritis and 42% of other children (P < 0.001). The median concentration of IL-8 was 188 pg/mumol in pyelonephritis; it was undetectable in controls (P < 0.001). IL-8 levels were higher in children less than 1 year of age (P < 0.001).

Acute Disease↗
PubMed1994

Urine interleukin-6 and interleukin-8 in children with acute pyelonephritis, in relation to DMSA scintigraphy in the acute phase and at 1-year follow-up.

The relationship between urine interleukin-6 (IL-6) and interleukin-8 (IL-8)/creatinine quotients and 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy, performed within 10 days of acute first-time pyelonephritis and after 1 year, was studied in 41 children. The urine IL-6 and IL-8/creatinine quotients were also related to the urine N-acetyl-beta-D-glucosaminidase (NAG) and albumin/creatinine quotients. Presence of DMSA uptake defects, reflecting local inflammation, in children in the acute phase of pyelonephritis, were associated with elevated urine IL-6/creatinine quotients (median 27 pg/mumol); in children without DMSA changes there was no increase in quotients (median non-detectable) (P < 0.05). Persistent DMSA changes at the 1-year follow-up, probably reflecting renal scarring, were only seen in children with increased urine IL-6/creatinine quotients in the acute phase (P < 0.01). No correlation was found between urine IL-8 and DMSA uptake defects. Vesicoureteral reflux (VUR) at 6-8 weeks did not correlate with the urine cytokine levels in the acute phase. The urine excretion of NAG and albumin, reflecting renal dysfunction, was associated with values of both urine IL-6 and IL-8/creatinine quotients, but not with DMSA defects or VUR. Thus, the initial urine IL-6/creatinine quotients might be used as an indicator of risk for persistent renal damage in acute pyelonephritis.

Acetylglucosaminidase↗