Outbreak caused by tobramycin-resistant Pseudomonas aeruginosa in a bone marrow transplantation unit.

Between May and August 1995, 5 patients in a bone marrow transplantation (BMT) ward developed bacteremia caused by Pseudomonas aeruginosa resistant to tobramycin (TRPA). Previously, isolates of TRPA had been limited to patients who were treated in 1 intensive care unit (ICU) of this tertiary care teaching hospital in Helsinki, Finland. To study whether the outbreak was caused by a single or multiple strains of P. aeruginosa, 102 isolates of TRPA from clinical samples obtained from different hospital units and 22 isolates obtained from the hospital environment were characterized by pulsed-field gel electrophoresis. All isolates from hematological patients produced 1 unique fragment pattern, which was also isolated from 3 ICU patients before the BMT ward outbreak began as well as from 5 shower heads in the BMT ward. The outbreak in the BMT ward was successfully controlled by eradicating the probable environmental source--contaminated hand showers--but the endemic infections continued in the ICU.

The conventionally ventilated operating theatre and air contamination control during cardiac surgery--bacteriological and particulate matter control garment options for low level contamination.

OBJECTIVE: The purpose of the study was to compare the usefulness of a conventional bacteriological technique with that of particle counting under lower air contamination and better aseptic conditions achieved with special staff garments and covering for the patient. Contamination levels were estimated with continuous on line air particle counting measurement, volumetric intermittent short period aerobic bacteriological cultures and wound surface contact cultures. METHODS: In a series of 66 consecutive coronary artery bypass operations performed by the same team and in the same theatre using different types of patient and staff clothing, the impact of a reduced bacteriological and particulate contamination were assessed. The volumetric air contamination of particles > or =5 microm and bacteria-carrying particles were monitored 30 cm above the sternal wound. The bacterial contamination and bacterial wound infections in the sternal and leg wounds were assessed as well. RESULTS: With the alternative garment and textile system, the air counts fell from 25 colony-forming units (CFU)/m3 to 7 CFU/m3 (P < 0.0038). The contamination of the sternal wound was reduced by 46% and that of the leg wound by >90%. In order to give continuous contamination feedback during the whole operation to the theatre staff, particle counts > or =5 microm were monitored and visualized. Air particle counts decreased rapidly from 850 particles/m3 and stabilized to approximately 50 particles/m3 when the alternative clothing system was used (P < 0.001). Low particle counts > or =5 microm should offer the possibility to indirectly estimate air bacteria carrying particle counts during the entire operation. Less than 20% of the total count in this size group carries bacteria. The low air contamination was achieved even in an ordinary ventilated theatre when individual team members used clean air suits in combination with impermeable patient drapes. When air particle level < or =50 particles/m3 is reached, the bacterial air contamination is in the order of that of orthopaedic hip operations. The staff must during the entire operation adjust their activity to air asepsis. CONCLUSIONS: The use of clean air suits and impermeable patient clothing results in a low exogenous contamination of air and wound. Continuous air particle monitoring is a good intraoperative method to monitor the air contamination longitudinally in an operating theatre.

Late onset Pneumocystis carinii pneumonia following allogeneic bone marrow transplantation.

We retrospectively reviewed all positive Pneumocystis carinii findings among adult patients who had received an allogeneic BM transplant at the Helsinki University Central Hospital between July 1990 and December 1993. The aim was to define the incidence of late onset Pneumocystis carinii pneumonia (PCP) in BMT patients who had routinely received PCP prophylaxis for 6 months post-BMT. In 110 BMT patients, 16 episodes of PCP were documented. Only one patient had been receiving PCP prophylaxis at the onset of PCP. Fourteen of the episodes occurred more than 6 months post-BMT. (median 10.5, range 4-42 months); three of them beyond 1 year. All three had extensive chronic GVHD. Of the 11 patients with an onset between 7-12 months post-BMT, all but one were on methylpredisolone because of chronic GVHD (n = 7) or cytopenia (n = 2) and five of them were in relapse of their hematological malignancy. No mortality from PCP was detected. The risk of developing PCP between 7-12 months post-BMT among patients at risk was 13.4%. We conclude that PCP prophylaxis should be continued until 1 year post-BMT in patients receiving corticosteroid treatment as well as in those with a hematological relapse. Long-term prophylaxis beyond 1 year should be considered in cases with extensive chronic GVHD.

Increased resistance among Staphylococcus epidermidis isolates in a large teaching hospital over a 12-year period.

The prevalence of drug resistance among clinically significant blood isolates of Staphylococcus epidermidis (n = 464) and consumption of antibiotics at a tertiary care teaching hospital (Meilahti Hospital, Helsinki) were analysed for the period 1983-1994. Resistance to methicillin increased from 28 to 77%. Simultaneously, usage of third-generation cephalosporins increased nearly sevenfold (from 8.6 kg/ to 56.4 kg/year). A significant correlation was found between percentages of methicillin resistance and usage of penicillinase-stable beta-lactam agents, including cloxacillin, imipenem, and first-, second-, and third-generation cephalosporins (r = 0.737, p < 0.0062). The increase in ciprofloxacin resistance occurred soon after the introduction of ciprofloxacin. Moreover, there was a remarkable increase in resistance to fusidic acid (from 10 to 40%) and rifampin (from 0 to 23%) despite the low usage of these agents. Overall, the rate of multiply resistant isolates roughly tripled (from 20 to 71%) and, by 1994, the frequency of isolates susceptible to vancomycin only was as high as 11%, which remarkably limits options for therapy.