Differentiation and identification of Enterococcus durans, E. hirae and E. villorum.

AIMS: To compare different tests in the identification of Enterococcus durans, E. hirae and E. villorum strains. These bacteria belong to the E. faecium species group and are phylogenetically closely related, as evidenced by 16S rRNA sequence homologies of over 98.8%. METHODS AND RESULTS: Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis of whole-cell protein, tRNA interpacer polymerase chain reaction (PCR) and arbitrarily-primed (D11344-primed AP) -PCR analysis correctly identified all three species in a collection of strains from very diverse origins. In contrast, biochemical reactions only allowed the unequivocal differentiation of the three species as a group from the other enterococci. Within this group, D-xylose acidification can be used to differentiate E. villorum, but exceptions occur. Strains highly susceptible to clindamycin can be identified as E. durans, but many strains of this species cannot be differentiated from E. hirae and E. villorum due to acquired resistance. CONCLUSIONS: Despite their close relationship, E. durans, E. hirae and E. villorum can be differentiated by genomic methods and by whole-cell protein analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Only a minority of strains of these three enterococcal species can be identified reliably by the currently available and commonly applied phenotypic tests.

Recurrent bacteremia by Chryseobacterium indologenes in an oncology patient with a totally implanted intravascular device.

Chryseobacterium indologenes was isolated from the blood cultures of an oncological patient with a totally implantable device. Because a catheter-related infection was suspected, the Port-A-Cath was removed after a 10-day course of piperacillin-tazobactam. Differences in susceptibility may exist if either the criteria for either Pseudomonas or Enterobacteriaceae are used.

Nasal and cutaneous carriage of Staphylococcus aureus in hemodialysis patients: the effect of nasal mupirocin.

Fifteen of 20 hemodialysis patients who carried Staphylococcus aureus in their nares also carried the organism on their hands; 2 of 20 patients who did not carry S aureus in their nares carried S aureus on their hands (P < .001). Eighty-seven percent of patients who carried S aureus in their nares and on their hands carried the same strain at both sites. Intranasal mupirocin eliminated S aureus from both sites.

Fatal Aeromonas hydrophila bacteremia in a hemodialysis patient treated with deferoxamine.

A 49-year-old woman undergoing long-term hemodialysis and treated with deferoxamine (DFO) 1.5 g twice weekly for aluminum bone disease developed fever and bilateral calf pain caused by myonecrosis with gas gangrene. She had a rapidly fatal outcome. The cultures of blood and aspirates from both calf muscles demonstrated Aeromonas hydrophila. No obvious entry point could be traced. The in vitro growth of the patient's strain was found to be stimulated by the deferoxamine-iron complex in an iron-deprived medium. It is suggested that high-dose DFO therapy in this patient was responsible for promoting a bacterial infection by this microorganism.

Susceptibility of clinical isolates of Fusarium to antifungal drugs.

The inhibitory activities of amphotericin B, fluconazole, itraconazole, miconazole, ketoconazole and terbinafine against nine isolates from clinically apparent infections of Fusarium solani, four isolates of Fusarium moniliforme and 10 isolates of Fusarium oxysporum were determined with an agar diffusion method (Neosensitabs) and an agar dilution method. The inhibition zones obtained with antifungal Neosensitabs need very careful interpretation. We did not find a good correlation between the agar diffusion method using Neo-sensitabs preloaded with azoles and amphotericin B and the agar dilution method. Amphotericin B (12/23) and terbinafine (18/23) showed good activity. Miconazole (7/23) and ketoconazole (3/23) had poor inhibitory activity. Fluconazole and itraconazole (0/23) had no in vitro activity against any of the isolates tested.

Staphylococcus aureus infections in haemodialysis patients: pathophysiology and use of nasal mupirocin for prevention.

Staphylococcus aureus is the most frequently (42%) isolated micro-organism during bacteraemic episodes in haemodialysis patients. Nasal carriage of S. aureus is of major importance in determining the risk of subsequent infections. Indeed, nasal carriage of S. aureus is highly prevalent in uraemic patients from the onset of maintenance dialysis therapy. The strains isolated simultaneously from the nares and the hands are usually the same. Likewise, infecting S. aureus strains and those isolated from nasal surveillance cultures obtained in the same patient are usually similar. S. aureus infections in haemodialysis patients are thus mostly to be considered as auto-infections. The nares are therefore an elective site for the prevention of S. aureus infections in haemodialysis patients. This has been demonstrated with oral rifampin, and more recently with nasal mupirocin, which is highly effective. Long-term application of nasal mupirocin (e.g. once per week) is cost-effective and is only rarely associated with the emergence of mupirocin-resistance in S. aureus.

Comparison of three rapid methods, tributyrine, 4-methylumbelliferyl butyrate, and indoxyl acetate, for rapid identification of Moraxella catarrhalis.

Moraxella catarrhalis can easily be differentiated from other oxidase-positive, gram-negative cocci with tributyrine, 4-methylumbelliferyl butyrate, or indoxyl acetate. All M. catarrhalis give positive reactions, and all Neisseria spp. give negative reactions. The 4-methylumbelliferyl butyrate tube test and indoxyl acetate strip test provide same-day identification of M. catarrhalis isolates.

Epidemiology of Staphylococcus aureus infections in patients on hemodialysis.

OBJECTIVE: To determine the epidemiology of Staphylococcus aureus infections in hemodialysis patients. METHOD: S aureus isolates from surveillance cultures and from sites of infection were evaluated by both bacteriophage typing and restriction endonuclease digestion of plasmid DNA. SETTING: A hemodialysis unit in Brugge, Belgium. ORGANISMS: S aureus isolates from 11 chronic hemodialysis patients who had participated in the placebo arm of a previously reported placebo-mupirocin comparative study. RESULTS: Of 75 S aureus isolates evaluated, 63 were from cultures of nares and 12 from infections (three arteriovenous fistula infections, four wound infections, and five bacteremias). All isolates were typed by bacteriophages and 56 (75%) had plasmids. Three patients developed 12 infections. Eleven infections were caused by isolates previously identified in surveillance cultures. Only one infection was caused by a strain not identified previously in surveillance cultures. CONCLUSION: These results support the hypothesis that S aureus isolates causing infections in hemodialysis patients are of endogenous origin.

[Epidemiology and prevention of Staphylococcus aureus infections during hemodialysis]. / Epidémiologie et prévention des infections à Staphylococcus aureus en hémodialyse.

Staphylococcus aureus is the pathogen most often isolated from blood during bacteraemic episodes in haemodialysis patients (42%). The pathophysiology of these infections is discussed and a prophylactic strategy is proposed. Nasal carriage of S. aureus, found in 42% of haemodialysis patients, plays a major role in its cutaneous dissemination and hence in the risk of infection by this microorganism. Long-term use of nasal mupirocin in haemodialysis patients with nasal carriage of S. aureus (t.i.d. for 3 to 5 days, followed by once a week) led to a decrease in the yearly incidence of S. aureus bacteraemia from 0.097 to 0.024 (p < 0.01). Tolerance was excellent. This chemoprophylaxis results in substantial savings. When applied as proposed (only nasal application), the long-term use of mupirocin only very rarely leads to the emergence of mupirocin-resistance in S. aureus (1 case in 165 patient-years).

Prosthetic valve endocarditis due to Listeria monocytogenes. A case report with review of the literature.

We report the case of a 71-year-old man with a prosthetic aortic valve endocarditis caused by Listeria monocytogenes. He was successfully treated with a combination of ampicillin and amikacin, and valve replacement surgery. This case and previously reported cases are discussed.

Mucormycosis during deferoxamine therapy is a siderophore-mediated infection. In vitro and in vivo animal studies.

This study investigates the pathophysiology of mucormycosis caused by Rhizopus, which has been reported in 46 dialysis patients, while treated with deferoxamine (DFO). This drug aggravates mucormycosis, which we experimentally induced in guinea pigs and which lead to a shortened animal survival (P < or = 0.01). The drug's effect on Rhizopus is not mediated through the polymorphonuclear cells. Fe.DFO, the iron chelate of DFO, abolishes the fungistatic effect of serum on Rhizopus and increases the in vitro growth of the fungus (P < or = 0.0001). This effect is present at Fe.DFO concentrations > or = 0.01 microM, at which fungal uptake of radioiron from 55Fe.DFO is observed. A 1,000-fold higher concentration of iron citrate is required to achieve a similar rate of radioiron uptake and of in vitro growth stimulation as observed with Fe.DFO. These in vitro effects of Fe.DFO (1 microM) in serum on radioiron uptake and on growth stimulation are more striking for Rhizopus than for Aspergillus fumigatus and are practically absent for Candida albicans. For these three fungal species, the rates of radioiron uptake from 55Fe.DFO and of growth stimulation in the presence of Fe.DFO in serum are directly related (r = 0.886). These results underscore the major role of Fe.DFO in the pathogenesis of DFO-related mucormycosis. Pharmacokinetic changes in uremia lead to a prolonged accumulation of Fe.DFO after DFO administration, which helps explain the increased sensitivity of dialysis patients to DFO-related mucormycosis.

Effect of ferrioxamine on the growth of Rhizopus.

Zygomycosis, caused by Rhizopus spp., has recently been reported to occur in dialysis patients treated with desferrioxamine, suggesting a role of this drug in the pathogenesis of this infection. The hypothesis that ferrioxamine, the iron chelate of desferrioxamine, stimulates the growth of Rhizopus spp. has been brought forward. The growth rate of 2 x 10(5) spores of R. rhizopodiformis (isolated from a dialysis patient who died of zygomycosis while on desferrioxamine therapy) was studied in an iron-deficient medium (1) with human serum at increasing concentrations and (2) with 40% human serum in the presence of ferrioxamine at different concentrations. After grinding the mycelium, growth was measured by absorbance density at 450 nm. The results show that a concentration of 40% human serum inhibits the growth of R. rhizopodiformis > 50% and that, in the presence of serum, ferrioxamine causes a significant growth stimulation at 24 h that persists at 48 h. In conclusion, ferrioxamine stimulates the growth of R. rhizopodiformis in vitro. This probably plays a key role in the pathogenesis of desferrioxamine-related zygomycosis.

Nasal mupirocin ointment decreases the incidence of Staphylococcus aureus bacteraemias in haemodialysis patients.

The incidence of S. aureus bacteraemia in a haemodialysis unit was studied over 2 years (167.75 patient-years of follow-up) during which nasal calcium mupirocin was used to eradicate nasal S. aureus carriage; this incidence was compared to that previously observed in the same unit before the use of nasal mupirocin (185.8 patient-years). Nasal mupirocin led to eradication of nasal S. aureus carriage in 96.3% of surveillance cultures and to a fourfold reduction in the incidence of S. aureus bacteraemia per patient-year, from 0.097 before mupirocin to 0.024 with mupirocin use (P = 0.008). Once or thrice weekly maintenance regimens of mupirocin were equally efficacious. The incidence of bacteraemia caused by other micro-organisms was not significantly affected. One single mupirocin-resistant isolate was identified in a nasal surveillance culture. Eradication of S. aureus from the nares did not lead to overgrowth by other micro-organisms. Chemoprophylaxis with nasal mupirocin in haemodialysis patients is cost-effective.

The use of nasal mupirocin ointment to prevent Staphylococcus aureus bacteraemias in haemodialysis patients: an analysis of cost-effectiveness.

Nasal carriage of Staphylococcus aureus is a risk factor for the development of infections caused by S. aureus in haemodialysis patients. This study compared the incidence of bacteraemia caused by S. aureus during 6 months of use of nasal 2% calcium mupirocin ('Nasal Bactroban') 3-times a week for nasal carriers with the incidence observed previously in the same dialysis unit without the use of mupirocin. Nasal mupirocin led to the total eradication of nasal carriage of S. aureus, a 4.26-fold reduction in the incidence of S. aureus bacteraemia, and a substantial cost saving. After a cumulative experience of nasal mupirocin in haemodialysis patients of more than 43 patient-years, the development of mupirocin resistance was not observed.

Isolation of Prototheca zopfii from a finger. Case report and review of the literature.

Prototheca zopfii, an alga-like organism, was isolated from subungual material in a patient with onycholysis. This organism seldom causes human infections. Clinical and laboratory aspects are described. The literature is reviewed.

Fatal septicemia with Capnocytophaga canimorsus in a compromised host. A case report with review of the literature.

Capnocytophaga canimorsus (DF-2) is a newly described gram-negative bacterium that can produce serious infections following dog bites in the immunocompromised host. We are reporting a case of C. canimorsus infection in an elderly patient with a history of chronic respiratory disease and alcohol abuse. We also give a review of the clinical spectrum of the infection, discuss the difficulty in establishing the diagnosis and the preferential treatment.

The importance of the quinolones in antibacterial therapy.

New quinolones have obtained a definite position in the treatment of certain sexually transmitted diseases, urinary tract infections, prostatitis, gastrointestinal infections, nosocomially acquired pulmonary infections with resistant organisms, pseudomonas infections in cystic fibrosis, and osteomyelitis. The role of the new quinolones in upper respiratory tract infections, acute or chronic bronchitis and community acquired pneumonia is far less established. Their role in selective decontamination of the gastrointestinal tract in neutropenic patients is under investigation. Future modifications may increase their usefulness for treatment of mycobacterial infections, chlamydial infections, and mycoplasma and ureaplasma infections. The structural relationship of the new quinolones with antimalarial drugs may open new perspectives for the treatment of falciparum malaria.

Novel beta-lactamase from Capnocytophaga sp.

A novel beta-lactamase activity which confers resistance to expanded-spectrum cephalosporins and penicillins has been found in strain IC 5/21 of Capnocytophaga spp. Enzyme activity migrated at a molecular size of 38,000 daltons and at an isoelectric point of 3.6, with a minor band at 4.1. Kinetic studies suggested that it belonged to Richmond and Sykes beta-lactamase class 1c. Isoelectric focusing could be achieved only if a nonionic detergent was added to the gel, suggesting the presence of a hydrophobic enzyme akin to a membrane-bound beta-lactamase of gram-positive bacteria. The location of the gene coding for this beta-lactamase is not yet known.

Iron overload in haemodialysis patients increases the risk of bacteraemia: a prospective study.

The incidence of bacteraemia in relation to the degree of transfusional iron overload was studied prospectively in patients from one haemodialysis unit over a 2-year period, with a total follow-up of 181.3 patient-years in 158 patients. Every 3 months, the patients were classified according to the serum ferritin in one of three groups: less than 500, 500-1000 or greater than 1000 micrograms/l. Twenty-nine episodes of bacteraemia were recorded over 181.3 patient-years (yearly incidence of 0.160). The yearly incidence of bacteraemia was 0.1173 and 0.1101 for ferritin less than 500 and 500-1000 micrograms/l (no significant difference), with a cumulative incidence for both groups of 0.1164. In the ferritin greater than 1000 micrograms/l group, the incidence was 0.3404 (P less than or equal to 0.005 versus the ferritin less than or equal to 1000 micrograms/l group). After stratification for patient's age (at inclusion in the study) and duration of haemodialysis therapy, the higher incidence of bacteraemia in the ferritin greater than 1000 versus less than or equal to 1000 micrograms/l groups persisted (P less than or equal to 0.005). This prospective study confirms previous retrospective studies in showing that acquired transfusional iron overload in haemodialysis is associated with a greater risk of bacteraemia.