Department of Quality Control, Reactivos para Diagnóstico, S.L., Barcelona, Catalonia, Spain.
Microbiology Section, Department of Biology, Healthcare and Environment, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, Barcelona, Catalonia, Spain.
Microbiol Spectr. 2022 Apr 27;10(2):e0240121. doi: 10.1128/spectrum.02401-21. Epub 2022 Mar 22.
Glycine-vancomycin-polymyxin-cycloheximide agar (GVPC) is a recommended medium for the detection of spp. in water samples. However, its quality could be improved in terms of recovery of spp. and selectivity properties. Modifications were introduced in GVPC manufacture: autoclaving conditions (115°C, 15 min) and atmosphere during component-stirring (removal of oxygen and N injection). The use of softer autoclaving conditions (115°C, 15 min) improved the growth of Legionella anisa by the spiral method and Legionella pneumophila after membrane filtration. The medium manufactured with O removal and autoclaving for 15 min at 115°C allowed a faster growth of L. pneumophila (colonies visible at day 2) and a notable increase of L. anisa growth (colonies appearing at day 3, and statistically significant numbers of CFU at day 5). After 3 to 5 days of incubation, the improved media showed higher selectivity properties, particularly for Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 9027. A further improvement was achieved by the addition of N during ingredient stirring, leading to a statistically significant faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3. Selectivity properties were also enhanced, resulting in the complete inhibition of both E. faecalis strains and Escherichia coli and complete-partial inhibition of P. aeruginosa. Oxygen removal during GVPC manufacture using a vacuum pump system promotes the growth of L. pneumophila and L. anisa, and markedly inhibits the growth of E. coli, P. aeruginosa, and E. faecalis. Currently, GVPC is a recommended medium for the detection of spp. in water samples. However, recovery of spp. and selectivity properties can be improved. GVPC medium manufactured without oxygen improved the growth of Legionella pneumophila and Legionella anisa. Oxygen removal during GVPC manufacture also improved selectivity properties. A further improvement was achieved by the addition of N during ingredient stirring, leading to a faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3 and enhancement of selectivity properties. The introduction of the modified GVPC medium in routine practice can allow a better detection of spp. in water samples.
甘氨酸-万古霉素-多黏菌素-环丝氨酸琼脂（GVPC）是一种推荐用于检测水中 spp. 的培养基。然而，它在 spp. 的回收率和选择性方面可以得到改善。在 GVPC 的生产过程中进行了改进：高压灭菌条件（115°C，15 分钟）和搅拌过程中的气氛（去除氧气和氮气注入）。使用较软的高压灭菌条件（115°C，15 分钟）通过螺旋法改善了嗜肺军团菌和膜过滤后的嗜肺军团菌的生长。使用去除氧气并在 115°C 下进行 15 分钟高压灭菌的培养基允许更快地生长嗜肺军团菌（第 2 天可见菌落），并显著增加嗜肺军团菌的生长（第 3 天出现菌落，第 5 天 CFU 数量有统计学意义）。孵育 3 至 5 天后，改良培养基显示出更高的选择性，特别是对粪肠球菌 ATCC 29212 和铜绿假单胞菌 ATCC 9027。通过在成分搅拌过程中添加氮气，进一步提高了嗜肺军团菌和嗜肺军团菌的生长速度，在第 2 天和第 3 天以及嗜肺军团菌在第 3 天的生长速度有统计学意义。选择性也得到了增强，导致两种粪肠球菌菌株和大肠杆菌完全抑制，铜绿假单胞菌完全部分抑制。使用真空泵系统在 GVPC 生产过程中去除氧气促进了嗜肺军团菌和嗜肺军团菌的生长，并显著抑制了大肠杆菌、铜绿假单胞菌和粪肠球菌的生长。目前，GVPC 是一种推荐用于检测水中 spp. 的培养基。然而，它的回收率和选择性可以得到改善。不添加氧气的 GVPC 培养基改善了嗜肺军团菌和嗜肺军团菌的生长。在 GVPC 生产过程中去除氧气也改善了选择性。通过在成分搅拌过程中添加氮气进一步提高了嗜肺军团菌在第 2 天和第 3 天以及嗜肺军团菌在第 3 天的生长速度，并增强了选择性。在常规实践中引入改良的 GVPC 培养基可以更好地检测水中的 spp.。
