Legionella spp. in UK composts--a potential public health issue?

Over the past 5 years, a number of cases of legionellosis in Scotland have been associated with compost use; however, studies investigating sources of infection other than water systems remain limited. This study delivers the first comprehensive survey of composts commonly available in the UK for the presence of Legionella species. Twenty-two store-bought composts, one green-waste compost and one home-made compost were tested for Legionella by culture methods on BCYE-α medium, and the findings were confirmed by macrophage infectivity potentiator (mip) speciation. Twenty-two of the samples were retested after an enrichment period of 8 weeks. In total, 15 of 24 composts tested positive for Legionella species, a higher level of contamination than previously seen in Europe. Two isolates of Legionella pneumophila were identified, and Legionella longbeachae serogroup 1 was found to be one of the most commonly isolated species. L. longbeachae infection would not be detected by routine Legionella urinary antigen assay, so such testing should not be used as the sole diagnostic technique in atypical pneumonia cases, particularly where there is an association with compost use. The occurrence of Legionella in over half of the samples tested indicates that compost could pose a public health risk. The addition of general hygiene warnings to compost packages may be beneficial in protecting public health.

Bioremediation of tributyltin contaminated sediment: degradation enhancement and improvement of bioavailability to promote treatment processes.

Bioremediation of tributyltin (TBT) contaminated sediment was studied and degradation enhancement and improvement of bioavailability were also investigated. In TBT spiked sediment, the half-life of TBT in the control sample, representing natural attenuation, was 578 d indicating its persistence. In the stimulated sample (pH 7.5, aeration and incubated at 28°C), the half-life was significantly reduced to 11 d. Further stimulation by nutrient addition (succinate, glycerol and l-arginine) or inoculation with Enterobacter cloacae (∼10(7) viable cells g(-1) of sediment) resulted in half-life reduction to 9 and 10d, respectively. In non-spiked sediment, the indigenous microorganisms were able to degrade aged TBT, but the extended period of contamination decreased the degradation efficiency. To improve bioavailability, addition of surfactant, adjustment of salinity and sonication were studied. The highest percentage solubilisation of TBT in water was obtained by adjusting salinity to 20 psu, which increased the solubility of TBT from 13% to 33%. Half-lives after bioavailability was improved were 5, 4 and 4d for stimulation, stimulation w/nutrient addition and stimulation w/inoculation, respectively. However, natural attenuation in the control sample was not enhanced. The results show that providing suitable conditions is important in enhancing TBT biodegradation, and bioavailability improvement additionally increased the rate and degraded amount of TBT. Unfortunately, nutrient addition and inoculation of the degrader did not enhance the degradation appreciably.

Decanting versus sterile pre-filled nutrient containers--the microbiological risks in enteral feeding.

A simulated ward study was carried out to compare the microbiological risk of assembling and running four different enteral feeding systems for 24 h. Assembly was carried out, (i) according to manufacturers' instructions with hands either covered by disposable gloves or deliberately contaminated with a test organism, or (ii) touching both the nutrient container top and pump set connector with hands deliberately contaminated with K. aerogenes. Two of the systems were ready-to-hang types (pack and bottle), the other two required feed to be decanted from either bottles or cans. When manufacturers' instructions were followed and disposable gloves worn, organisms were only detected in feeds decanted from cans and at levels < or = 20 cfu ml(-1). However, when systems were assembled following manufacturers' instructions, but with contaminated hands, no organisms were found in either of the ready-to-hang systems but average bacterial counts in samples from systems where the feed was decanted from bottles were 1.8 x 10(3) cfu ml(-1) at 24 h and 9.3 x 10(5) cfu ml(-1) for those where feed was decanted from cans. When systems were deliberately touched with contaminated hands, no organisms were detected in any feed samples from the pack system at 24 h, while bacterial counts for the other three systems ranged from 10(1) to 10(5) cfu ml(-1). The results highlight the important role played by system design in reducing both the level and incidence of bacterial contamination of enteral tube feeds and indicate that ready-to-hang feeding systems should be the preferred choice. However, if decanting of feeds cannot be avoided then strict adherence to manufacturers' instructions and the use of disposable gloves is to be advised.

Microbiological evaluation of four enteral feeding systems which have been deliberately subjected to faulty handling procedures.

The present study was designed to investigate the levels of contamination in four currently used 1000 mL, 'ready-to-hang', enteral feeding systems--Osmolite (Ross Ready-To-Hang), Steriflo, Dripac-flex and Easybag, when faulty handling procedures were used during assembly of the systems. The top of the nutrient container and the proximal (container) end of the pump set of each system were touched during assembly by a researcher whose hands had been deliberately contaminated with Klebsiella aerogenes. Once assembled systems were run continuously for 24 h delivering 1000 mL of feed. Feed samples for microbiological analysis were taken from the distal (patient) end of the feeding tube at 0 h and 24 h and from the feed remaining in the nutrient container at the end of administration (24 h). Five systems of each type were run. Five controls were also run for each type of system, where all procedures were carried out wearing sterile gloves. Eighty-seven percent of feed samples collected from the Osmolite systems and 80% of those from the Steriflo systems were found to contain K. aerogenes, with 13% of feed samples from both systems containing > or = 10(4) cfu/mL, a level of contamination, considered by many, as that above which feed is unacceptable for patient consumption. The percentage of feed systems containing the test organism was much lower in the Dripac-flex and Easybag systems, with K. aerogenes being detected in 27% and 13% of samples respectively. No feed samples from either of these systems contained > or = 10(4) cfu/mL. From the results it can be concluded that deviation from the manufacturers instructions when assembling enteral feeding systems can lead to bacterial contamination of these systems. The results also highlight the effect that system design, such as recessed pump set spikes and recessed nutrient container seals (both of which prevent care workers accidentally touching parts of the feeding system which may come into contact with the feed) have on reducing the number of bacteria gaining entry to the feed in the systems.