Zanon Vincenzo, Rossi Lucia, Castellani Elena, Camporesi Enrico Mario, Palù Giorgio, Bosco Gerardo
ATiP, Diving & Hyperbaric Medicine Center, Padua, Italy.
Med Gas Res. 2012 Sep 11;2(1):24. doi: 10.1186/2045-9912-2-24.
HyperBaric Oxygen (HBO) therapy involves exposure to pure oxygen in a pressurized room, and it is an already well-established treatment for various conditions, including those originated by serious infections. Starting from the observation of an increased number of patients who were accessing our HBO units for diseases supported from concomitant multidrug-resistant microorganisms, as well as considering the evident clinical benefit and laboratory final outcome of those patients at the end of the treatment, aim of our study was to measure, or better define at least, if there was any interaction between a hyperbaric environment and some selected microorganisms and if those positive results were due to the increased oxygen partial pressure (pO2) value or just to the increased pressure, regardless of the fraction of inspired oxygen (FiO2) applied (21÷100%).
We applied various increased pO2 values in a hyperbaric environment. Our study design was tailored in four steps to answer four specific questions, ordered in a progressive process: OxyBioTest (OBT)-1,2,3, and 4. Specifically, we chose to investigate possible changes in the Minimum Inhibitory Concentration (MIC) and in the Minimum Bactericidal Concentration (MBC) of multi-resistant microorganisms after a single session of hyperbaric therapy.
OBT-1 and OBT-2 provide a semi-quantitative confirmation of the bacterio-cidal and cytostatic effects of HBO. HBO is cidal only if the total exposure pressure is elevated, and cidal or cytostatic effect are not always dependent on the pO2 applied.OBT-4 has shown the adjuvant effect of HBO and antimicrobial drug against some selected bacteria.
We seem allowed to hypothesize that only in case of a good approach to a lesion, permitting smaller bacterial loads thanks to surgical debridement and/or eventual antibiotic therapy for example, You can observe the clear effectiveness of the HyperBaric Oxygen (HBO) exposure as a valid adjuvant therapy, even when that lesion is substained from multidrug-resistant micro-organisms. On the contrary when the bacterial load is very high we observe an unchanged situation or a just a slightly diminishing in the number of cfu/ml.
Even if confined in this 'in vitro' environment and in a single treatment, just knowing the microorganism strain responsible of the lesion we seem allowed to both weight the possible related effectiveness using HBO Therapy (HBOT) and derive the best pO2 to treat the case. A further possible development of the study highlights a comparison between Acinetobacter baumannii (ACBA) and Pseudomonas aeruginosa (PSAE), and Escherichia coli (ESCO) and Klebsiella pneumoniae (KLPN).
高压氧（HBO）疗法是在加压舱内吸入纯氧，它是一种已被广泛应用于多种病症的成熟治疗方法，包括由严重感染引发的病症。从观察到越来越多因合并多重耐药微生物感染而前来接受HBO治疗的患者，以及考虑到这些患者在治疗结束时明显的临床获益和实验室最终结果出发，我们研究的目的是测量，或者至少更好地确定，高压环境与某些特定微生物之间是否存在相互作用，以及这些阳性结果是由于氧分压（pO2）值升高，还是仅仅由于压力升高，而与所应用的吸入氧分数（FiO2）（21%至100%）无关。
我们在高压环境中应用了各种升高的pO2值。我们的研究设计分四个步骤进行，以回答四个特定问题，按递进过程排列：氧生物测试（OBT）-1、2、3和4。具体而言，我们选择研究单次高压治疗后多重耐药微生物的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）可能发生的变化。
OBT-1和OBT-2半定量证实了HBO的杀菌和抑制细胞生长作用。只有当总暴露压力升高时，HBO才具有杀菌作用，且杀菌或抑制细胞生长作用并不总是依赖于所应用的pO2。OBT-4显示了HBO和抗菌药物对某些特定细菌的辅助作用。
我们似乎可以假设，只有在对病变采取良好处理方法的情况下，例如通过手术清创和/或最终的抗生素治疗使细菌载量降低，才可以观察到高压氧（HBO）暴露作为一种有效的辅助治疗方法的明显效果，即使该病变由多重耐药微生物引起。相反，当细菌载量非常高时，我们观察到每毫升菌落形成单位（cfu/ml）数量不变或仅略有减少的情况。
即使局限于这种“体外”环境且仅进行单次治疗，只要知道引起病变的微生物菌株，我们似乎就可以权衡使用高压氧疗法（HBOT）可能产生的相关效果，并得出治疗该病例的最佳pO2。该研究的进一步可能发展方向是比较鲍曼不动杆菌（ACBA）与铜绿假单胞菌（PSAE），以及大肠杆菌（ESCO）与肺炎克雷伯菌（KLPN）。
