Improved bacteriological surveillance of haemodialysis fluids: a comparison between Tryptic soy agar and Reasoner's 2A media

Abstract

Microbiological surveillance of haemodialysis fluids, including pre-treated dialysis water samples collected from RO treatment systems, can be performed more precisely with R2A media than TSA, when incubated at 25+/-2 degrees C for 10 days.

Isolation of Optically Targeted Single Bacteria by Application of Fluidic Force Microscopy to Aerobic Anoxygenic Phototrophs from the Phyllosphere

“…To demonstrate that FluidFM technology can be used to isolate bacteria, we first used clover leaf washes and randomly selected individual bacteria for subsequent isolation of liquid R2A medium (52). R2A medium was used to cultivate the bacteria, because a wide range of bacteria are able to multiply in this medium and it is commonly used to isolate various bacteria from environmental samples.…”

Airborne microorganisms in the African desert dust corridor over the mid-Atlantic ridge, Ocean Drilling Program, Leg 209

“…Employment of a low nutrient substrate such as R2A limits nutrient-shock which may be experienced by stressed cells plated on a nutrient rich substrate and numerous studies have shown that R2A gives superior recovery of CFU in comparison to high nutrient substrates in many different settings (body fluids, water, etc.) (Guerrero, 1987;Horgan, Matheson, McLoughlin-Borlace, & Dart, 1999;Lesne, Berthet, Binard, Rouxel, & Humbert, 2000;Massa, Caruso, Trovatelli, & Tosques, 1998;Reasoner, 2004;Reasoner & Geldreich, 1985;van der Linde, Lim, Rondeel, Antonissen, & de Jong, 1999). A number of studies have successfully utilized R2A to recover bacteria from soils, the lower atmosphere, and extreme atmospheric altitudes (Bodour, Drees, & Maier, 2003;Gentry, Newby, Josephson, & Pepper, 2001;Griffin, 2004;Griffin et al, 2003;Kellogg et al, 2004;Ovreas & Torsvik, 1998).…”

Comparison of techniques for culture of dialysis water and fluid

“…24 A number of studies report that lower nutrient levels and temperature promote recovery of more bacteria from water samples than are recovered at higher nutrient levels and temperatures. 13,16,19 It has been observed that dialysis fluid does not always yield the same taxa that are recovered from the water used to prepare the fluid, 25,26 that bacteria likely to be pathogenic and those acquired nosocomially are better recovered on high nutrient media at higher temperatures, 17,23 and that "A particular hazard is introduced when the water temperature is raised to 37C within the dialysis machine, since this temperature supports growth of the more dangerous mesotropic bacteria, for example, P. aeruginosa or S. aureus.…”

“…12 Both approaches have microbiologic rationales: TGEA and R2A methods are performed at a temperature and nutrient level close to that of dialysis water and its resident microorganisms, and have been shown to yield higher colony counts in several studies. 10,[13][14][15][16] TSA-48h cultures are performed at the temperature at which the patient is exposed to dialysis fluid in the dialyzer. 17 In addition, TSA-48h has the operational advantage that results are available more quickly, allowing earlier corrective action, and allows a laboratory to operate more efficiently.…”

“…Most previous studies examining the use of various methods to culture water and dialysis fluid ( Table 1) 18 concluded that lower nutrient medium, lower incubation temperatures and longer incubation times, similar to those specifically recommended by the ISO standards, result in higher total counts and better recovery of pigmented Gram negative organisms than do methods using higher nutrient content, shorter incubation times and higher incubation temperatures, [13][14][15][16]19 similar to the methods recommended by AAMI RD52, 10 incorporated into the CMS 2008 ESRD CfC, 11 and used in the U.S. Although the current international standards cite these studies to justify their recommendations, the studies are small, use samples of little relevance to the dialysis environment (such as potable water), use reference points higher than 50 CFU/mL, and are inconsistent in incubation conditions and in the pairing of culture methods compared.…”