Diagnosis and treatment of Aspergillus flavus sternal wound infections after cardiac surgery.

We report the clinical data for 9 patients affected during an outbreak of Aspergillus flavus sternal wound infections after cardiac surgery. In 7 patients, the infection had a locally invasive character, with 3 of these patients having multiple relapses; 2 patients had fulminant mediastinitis and died. Most patients received combined surgical and medical treatment.

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.

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.

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.

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.

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.

[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).

The influence of calcium mupirocin nasal ointment on the incidence of Staphylococcus aureus infections in haemodialysis patients.

Mupirocin was used in haemodialysis patients in an attempt to eradicate nasal carriage of Staphylococcus aureus and to prevent infection caused by this microorganism. The effectiveness of calcium mupirocin as a 2% nasal ointment OB2 (16 patients for 104 patient-months) was compared to that of placebo (18 patients for 147 patient-months) in a double-blind study. Mupirocin or placebo were applied in both anterior nares thrice daily for 2 weeks and subsequently three times weekly for a total of 9 months. During therapy, S. aureus was recovered from only 6% of the nasal cultures in the mupirocin group compared to 58% in the placebo group (P less than or equal to 0.01). Only one S. aureus infection was documented in the mupirocin group compared to six in the placebo group (P less than or equal to 0.05). The S. aureus strain causing the single infection in the mupirocin group was of a different phage type to that of the original nasal strain. In contrast, at least four of the six strains causing infection in the placebo group were of similar phage type to the original nasal strain. All S. aureus isolates remained mupirocin sensitive (MIC less than or equal to 1 mg/l). In conclusion, mupirocin nasal ointment was effective in eradicating nasal carriage of S. aureus and in preventing S. aureus infections in patients on haemodialysis.