Purpose The aim of this study was to monitor environmental contamination by 10 antineoplastic drugs in Canadian oncology pharmacy and patient care areas. The secondary objective was to explore the impact of factors that may explain contamination. Methods Twelve standardized sites were sampled in each center (six in the pharmacy and six in patient care areas). Each sample was prepared to allow quantification of seven antineoplastic drugs (cyclophosphamide, ifosfamide, methotrexate, cytarabine, gemcitabine, 5-fluorouracil, irinotecan) by UPLC-MS-MS. Docetaxel, paclitaxel and vinorelbine were also detected, but not quantified due to sensibility limitations. The impact of some factors was evaluated compared with a Kolmogorov-Smirnov test for independent samples. Results Eighty-three Canadian centers were recruited in 2017. A total of 953 surfaces were sampled, 495 in pharmacy and 458 in patient care areas. Cyclophosphamide was most often found on surfaces (36% of samples positive, 75th percentile 0.0040 ng/cm). The arm rest (81.7% of samples positive for at least one antineoplastic drug), the front grille inside the hood (78.3%) and the floor in front of the hood (61.4%) were more frequently contaminated. Centers who prepared more antineoplastic drugs per year had higher concentration on different surfaces ( p < 0.0001). Conclusion Despite growing awareness and implementation of new safe handling guidelines, healthcare centers' surfaces remain contaminated with traces of many antineoplastic drugs. The use of personal protective equipment remains indisputable. Performing an annual monitoring remains a good indicator to monitor trends over time and to compare with similar centers.
SummaryGyrase-mediated hypernegative supercoiling is one manifestation of R-loop formation, a phenomenon that is normally suppressed by topoisomerase I (topA) in Escherichia coli. Overproduction of RNase HI (rnhA), an enzyme that removes the RNA moiety of R-loops, prevents hypernegative supercoiling and allows growth of topA null mutants. We previously showed that topA and rnhA null mutations are incompatible. We now report that such mutants were viable when RNase HI or topoisomerase III was expressed from a plasmid-borne gene. Surprisingly, DNA of topA null mutants became relaxed rather than hypernegatively supercoiled following depletion of RNase HI activity. This result failed to correlate with the cellular concentration of gyrase or topoisomerase IV (the other relaxing enzyme in the cell) or with transcription-induced supercoiling. Rather, intracellular DNA relaxation in the absence of RNase HI was related to inhibition of gyrase activity both in vivo and in extracts. Cells lacking topA and rnhA also exhibited properties consistent with segregation defects. Overproduction of topoisomerase III, an enzyme that can carry out DNA decatenation, corrected the segregation defects without restoring supercoiling activity. Collectively these data reveal (i) the existence of a cellular response to loss of RNase HI that counters the supercoiling activity of gyrase, and (ii) supercoiling-independent segregation defects due to loss of RNase HI from topA null mutants. Thus RNase HI plays a more central role in DNA topology than previously thought.
There is currently no evidence to support or refute the routine use of closed-system drug transfer devices in addition to safe handling of infusional hazardous drugs, as there is no evidence of differences in exposure or financial benefits between CSTD plus safe handling versus safe handling alone (very low-quality evidence). None of the studies report health benefits.Well-designed multicentre randomised controlled trials may be feasible depending upon the proportion of people with exposure. The next best study design is interrupted time-series. This design is likely to provide a better estimate than uncontrolled before-after studies or cross-sectional studies. Future studies may involve other alternate ways of reducing exposure in addition to safe handling as one intervention group in a multi-arm parallel design or factorial design trial. Future studies should have designs that decrease the risk of bias and enable measurement of direct health benefits in addition to exposure. Studies using exposure should be tested for a relevant selection of hazardous drugs used in the hospital to provide an estimate of the exposure and health benefits of using CSTD. Steps should be undertaken to ensure that there are no other differences between CSTD and control groups, so that one can obtain a reasonable estimate of the health benefits of using CSTD.
Escherichia coli possesses two type 1A topoisomerases, Topo I (topA) and Topo III (topB). Topo I relaxes excess negative supercoiling, and topA mutants can grow only in the presence of compensatory mechanisms, such as gyrase mutations. topB mutants grow as well as wild-type cells. In vitro, Topo III, but not Topo I, can efficiently decatenate DNA during replication. However, in vivo, a chromosome segregation defect is seen only when both type 1A topoisomerases are absent. Here we present experimental evidence for an interplay between gyrase and type 1A topoisomerases in chromosome segregation. We found that both the growth defect and the Par ؊ phenotypes of a gyrB(Ts) mutant at nonpermissive temperatures were significantly corrected by deleting topA, but only when topB was present. Overproducing Topo IV, the major cellular decatenase, could not substitute for topB. We also show that overproducing Topo III at a very high level could suppress the Par ؊ phenotype. We previously found that the growth and chromosome segregation defects of a triple topA rnhA gyrB(Ts) mutant in which gyrase supercoiling activity was strongly inhibited could be corrected by overproducing Topo III (V. Usongo, F. Nolent, P. Sanscartier, C. Tanguay, S. Broccoli, I. Baaklini, K. Drlica, and M. Drolet, Mol. Microbiol. 69:968-981, 2008). We show here that this overproduction could be bypassed by substituting the gyrB(Ts) allele for a gyrB ؉ one or by growing cells in a minimal medium, conditions that reduced both topA-and rnhA-dependent unregulated replication. Altogether, our data point to a role for Topo III in chromosome segregation when gyrase is inefficient and suggest that Topo I plays an indirect role via supercoiling regulation.
Introduction Healthcare workers exposure to antineoplastic drugs can lead to adverse health effects. Guidelines promote the safe handling of antineoplastic drugs, but no safe exposure limit was determined. Regular surface sampling contributes to ensuring workers safety. Methods A cross-sectional monitoring is conducted once a year with voluntary Canadian centers, since 2010. Twelve standardized sampling sites were sampled. Samples were analyzed by high performance mass coupled liquid chromatography. The limits of detection (in ng/cm2) were: 0.001 for cyclophosphamide and gemcitabine; 0.3 for docetaxel and ifosfamide; 0.04 for 5-fluorouracil and paclitaxel; 0.003 for irinotecan; 0.002 for methotrexate; 0.01 for vinorelbine. Results The surfaces from 109 centers were sampled between 01/01/2020–18/06/2020. Twenty-six centers delayed their participation because of the COVID-19 pandemic. 1217 samples were analyzed. Surfaces were frequently contaminated with cyclophosphamide (34% positive, 75th percentile 0.00165 ng/cm2) and gemcitabine (16% and <0.001 ng/cm2). The armrest of patient treatment chairs (84% to at least one drug), the front grille inside the biological safety cabinet (BSC) (73%) and the floor in front of the BSC (55%) were frequently contaminated. Centers that prepared ≥5000 antineoplastic drugs annually had higher concentration of cyclophosphamide on their surfaces (p < 0.0001). Contamination measured on the surfaces was reduced from 2010 to 2020. Conclusions This large-scale study showed reproducible long term follow up of the contamination of standardized sites of Canadian centers and a reduction in surface contamination from 2010 to 2020. Periodic surface sampling help centers meet their continuous improvements goals to reduce exposure as much as possible. The COVID-19 pandemic had a limited impact on the program.
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