Infectious complications in 126 patients treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation.
(1/1206)
The effect of an extensive prophylactic antimicrobial regimen was prospectively assessed in 126 patients after high-dose chemotherapy and autologous PBSC. They received ciprofloxacin (500 mg/12 h), acyclovir (200 mg/6 h), and itraconazole (200 mg/12 h) orally until neutrophil recovery. Febrile patients received i.v. imipenem (500 mg/6 h) to which vancomycin and amikacin were added if fever persisted for 2-3 and 5 days, respectively. Amphotericin B lipid complex was further given on day 7 or 8 of fever. Median times for a neutrophil count of >0.5 x 10(9)/l and a platelet count of >20 x 10(9)/l were 9 and 11 days. Severe neutropenia (<0.1 x 10(9)/l) lasted for a median of 5 days in which 72% of febrile episodes and 50% of cases of bacteremia occurred. Gram-positive bacteria were isolated in 30 of 40 episodes of bacteremia, 25 of which were caused by Staphylococcus epidermidis. Clinical foci were the intravascular catheter in 35 cases, respiratory infection in 11, cellulitis in two, anal abscess in one, and neutropenic enterocolitis in one. The high incidence of febrile episodes (94%) and bacteremias (31%) may be due to the lack of efficacy of antimicrobial prophylaxis and the persistence of a 5-day period of severe neutropenia. (+info)
Identification and characterization of SirA, an iron-regulated protein from Staphylococcus aureus.
(2/1206)
The acquisition of iron by pathogenic bacteria is often a crucial step in establishing infection. To accomplish this, many bacteria, including Staphylococcus aureus, produce low-molecular-weight iron-chelating siderophores. However, the secretion and transport of these molecules in gram-positive organisms are poorly understood. The sequence, organization, and regulation of genes involved in siderophore transport are conserved among gram-negative bacteria. We used this information to identify a putative siderophore transport locus from an S. aureus genomic sequence database. This locus contains three predicted open reading frames with a high degree of homology to genes involved in siderophore uptake in several bacterial species, in particular the cbr locus of the plant pathogen Erwinia chrysanthemi. The first gene in the locus, which we have designated sir for staphylococcal iron regulated, encodes a putative lipoprotein with a molecular mass of 37 kDa. The open reading frame is preceded by a 19-bp region of dyad symmetry with homology for operator sequences controlling iron-regulated expression of genes in other bacteria. Fur titration experiments indicate that this region of dyad symmetry is sufficient for Fur-dependent regulation in Escherichia coli. The expression of this gene was repressed, in a dose-dependent manner, by the addition of iron to the S. aureus culture medium. sir-encoded proteins may be involved in iron acquisition in vivo and therefore may be targets for antimicrobial agents. (+info)
Changing susceptibilities of coagulase-negative staphylococci to teicoplanin in a teaching hospital.
(3/1206)
The susceptibility of two collections of coagulase-negative staphylococci (CNS) isolated from clinical specimens for teicoplanin and vancomycin were compared. They comprised 91 and 101 isolates, collected in 1985 and 1994 respectively, from different departments of a teaching hospital. MICs of vancomycin and teicoplanin were determined by a modified Etest method. Additionally, a disc diffusion test was performed for teicoplanin. All isolates were susceptible to vancomycin (MIC < or = 4 mg/L). Two of the 91 isolates collected in 1985 were intermediate to teicoplanin (MIC between 8 and 32 mg/L), whereas in 1994 the number of intermediate isolates was 20 out of 101 (P < 0.01). The correlation between MICs, as determined by the modified Etest assay, and disc diffusion zones was poor (r = -0.35). Results show that resistance to teicoplanin in CNS has increased in the study hospital over a period of 9 years. This increase is likely to be correlated with the introduction of teicoplanin. Furthermore, a disc diffusion method does not appear to be the first method of choice for detection of strains of CNS with diminished susceptibility to teicoplanin. (+info)
An inflammatory polypeptide complex from Staphylococcus epidermidis: isolation and characterization.
(4/1206)
Staphylococcus epidermidis releases factors that activate the HIV-1 long terminal repeat, induce cytokine release, and activate nuclear factor B in cells of macrophage lineage. The active material had a mass of 34,500 daltons, was inactivated by proteases and partitioned into the phenol layer on hot aqueous phenol extraction, and thus was termed phenol-soluble modulin (PSM). High performance liquid chromatography (HPLC) of crude PSM yielded two peaks of activity designated PSM peak 1 and peak 2. MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectroscopy indicated the presence of two components in peak 1, which were designated PSM and PSM. Peak 2 contained a single component, designated PSM. Separation of PSM and PSM in peak 1 could be achieved by a second HPLC procedure. The structure of each component was determined by amino acid sequence analysis and identification and sequencing of their genes. PSM, PSM, and PSM were 22-, 44-, and 25-amino acid, respectively, strongly hydrophobic polypeptides. PSM was identified as Staphylococcus epidermidis delta toxin, whereas PSM and PSM exhibited more distant homology to previously described staphylococcal toxins. They appeared to exist as a complex or aggregate with activity greater than the component parts. The properties of the S. epidermidis PSMs suggest that they may contribute to the systemic manifestations of Gram-positive sepsis. (+info)
Surface-grafted, environmentally sensitive polymers for biofilm release.
(5/1206)
Controlling bacterial biofouling is desirable for almost every human enterprise in which solid surfaces are introduced into nonsterile aqueous environments. One approach that is used to decrease contamination of manufactured devices by microorganisms is using materials that easily slough off accumulated material (i.e., fouling release surfaces). The compounds currently used for this purpose rely on low surface energy to inhibit strong attachment of organisms. In this study, we examined the possible use of environmentally responsive (or "smart") polymers as a new class of fouling release agents; a surface-grafted thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAAM), was used as a model compound. PNIPAAM is known to have a lower critical solubility temperature of approximately 32 degrees C (i.e., it is insoluble in water at temperatures above 32 degrees C and is soluble at temperatures below 32 degrees C). Under experimental conditions, >90% of cultured microorganisms (Staphylococcus epidermidis, Halomonas marina) and naturally occurring marine microorganisms that attached to grafted PNIPAAM surfaces during 2-, 18-, 36-, and 72-h incubations were removed when the hydration state of the polymer was changed from a wettability that was favorable for attachment to a wettability that was less favorable. Of particular significance is the observation that an organism known to attach in the greatest numbers to hydrophobic substrata (i.e., H. marina) was removed when transition of PNIPAAM to a more hydrated state occurred, whereas an organism that attaches in the greatest numbers to hydrophilic substrata (i.e., S. epidermidis) was removed when the opposite transition occurred. Neither solvated nor desolvated PNIPAAM exhibited intrinsic fouling release properties, indicating that the phase transition was the important factor in removal of organisms. Based on our observations of the behavior of this model system, we suggest that environmentally responsive polymers represent a new approach for controlling biofouling release. (+info)
Comparison of peritoneal fluid culture results from adults and children undergoing CAPD.
(6/1206)
BACKGROUND: Peritonitis is a common complication in patients with end-stage renal disease treated by continuous ambulatory peritoneal dialysis (CAPD). Empirical treatment is based on the organisms that are most frequently isolated and their susceptibilities. OBJECTIVE: To analyze and then compare peritoneal fluid culture results from adult and pediatric patients on CAPD, with respect to micro-organisms and antimicrobial susceptibilities. DESIGN: Three-year retrospective review of peritoneal fluid cultures from adults and children on CAPD. RESULTS: We isolated 481 organisms from 378 peritoneal fluid specimens, collected from 135 patients (45 children, 90 adults). There were 191 episodes of peritonitis in children (mean 4.2+/-3.5, range 1 - 15) compared to 187 in adults (2.1+/-1.9, range 1 - 10) (p< 0.001). Two or more episodes occurred in 30 of 45 children (67%) compared to 33 of 90 adults (37%) (p < 0.001).The number of different organisms/patient as well as the total number of isolates/patient were significantly greater in children (respectively, 2.8+/-2.3, range 1 - 12; and 5.3+/-5.2, range 1 - 27) than in adults (2.0+/-1.3, range 1 - 6; and 2.7+/-2.4, range 1 - 10) (p< 0.005). After Staphylococcus epidermidis, S. aureus was the most frequently isolated organism, occurring in 18% of episodes in adults and 12% of episodes in children (p< 0.01). Twenty-two of 33 fungal isolates (67%) in children were Candida parapsilosis compared to 3 of 24 (12%) in adults (p < 0.001). Subanalysis of multiple episodes revealed that Pseudomonas and Candida occurred significantly more often in children (p< 0.01), whereas S. aureus occurred more often in adults (p< 0.001). In polymicrobial episodes S. epidermidis occurred more often in adults (p < 0.05). Significant differences in susceptibilities to ampicillin, ceftriaxone, chloramphenicol, and gentamicin were found between children and adults (p< 0.05 - 0.001). CONCLUSIONS: CAPD-associated peritonitis occurs significantly more often in children than adults. Significant differences in microbial etiology and susceptibilities were found between pediatric and adult patients. Each dialysis unit should periodically analyze peritoneal fluid culture results from its CAPD patients. These data can then be used for optimization of empirical antimicrobial therapy of peritonitis. (+info)
Phenotypic and genomic variation among Staphylococcus epidermidis strains infecting joint prostheses.
(7/1206)
We studied the SmaI and SstII macrorestriction patterns of 54 Staphylococcus epidermidis strains isolated from 14 patients infected following the implantation of joint prostheses. Multiple strains from pus and infected tissue specimens of each patient were selected on the basis of different colony morphologies and drug resistance patterns. The same criteria were used to select 23 S. epidermidis strains from hand swabs of eight healthy individuals. For 10 of the 14 patients, all the intrapatient strains appeared to be closely or possibly related, whereas related strains were detected in the skin flora of only one of the eight healthy individuals. This observation suggests that, in most cases, the patients were infected by a single S. epidermidis clone which subsequently underwent rearrangements that yielded derivatives with divergent phenotypes and, occasionally, divergent macrorestriction patterns. The four patients whose specimens contained unrelated S. epidermidis strains were probably infected with several polyclonal strains. (+info)
Stool microflora in extremely low birthweight infants.
(8/1206)
AIM: To serially characterise aerobic and anaerobic stool microflora in extremely low birthweight infants and to correlate colonisation patterns with clinical risk factors. METHODS: Stool specimens from 29 infants of birthweight <1000 g were collected on days 10, 20, and 30 after birth. Quantitative aerobic and anaerobic cultures were performed. RESULTS: By day 30, predominant species were Enterococcus faecalis, Escherichia coli, Staphylococcus epidermidis, Enterbacter cloacae, Klebsiella pneumoniae, and Staphylococcus haemolyticus. Lactobacillus and Bifidobacteria spp were identified in only one infant. In breast milk fed (but not in formula fed) infants, the total number of bacterial species/stool specimen increased significantly with time (2.50 (SE 0.34) on day 10; 3.13 (0.38) on day 20; 4.27 (0.45) on day 30) as did quantitative bacterial counts; Gram negative species accounted for most of the increase. On day 30, significant inverse correlations were found between days of previous antibiotic treatment and number of bacterial species (r=0.491) and total organisms/g of stool (r=0.482). Gestational age, birthweight, maternal antibiotic or steroid treatment, prolonged rupture of the membranes, and mode of delivery did not seem to affect colonisation patterns. CONCLUSIONS: The gut of extremely low birthweight infants is colonised by a paucity of bacterial species. Breast milking and reduction of antibiotic exposure are critical to increasing fecal microbial diversity. (+info)