Division of Infectious Diseases, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Stellenbosch University, Cape Town, South Africa.
Clin Infect Dis. 2022 Oct 12;75(8):1297-1306. doi: 10.1093/cid/ciac183.
High rates of tuberculosis (TB) transmission occur in hospitals in high-incidence countries, yet there is no validated way to evaluate the impact of hospital design and function on airborne infection risk. We hypothesized that personal ambient carbon dioxide (CO2) monitoring could serve as a surrogate measure of rebreathed air exposure associated with TB infection risk in health workers (HWs).
We analyzed baseline and repeat (12-month) interferon-γ release assay (IGRA) results in 138 HWs in Cape Town, South Africa. A random subset of HWs with a baseline negative QuantiFERON Plus (QFT-Plus) underwent personal ambient CO2 monitoring.
Annual incidence of TB infection (IGRA conversion) was high (34%). Junior doctors were less likely to have a positive baseline IGRA than other HWs (OR, 0.26; P = .005) but had similar IGRA conversion risk. IGRA converters experienced higher median CO2 levels compared to IGRA nonconverters using quantitative QFT-Plus thresholds of ≥0.35 IU/mL (P < .02) or ≥1 IU/mL (P < .01). Median CO2 levels were predictive of IGRA conversion (odds ratio [OR], 2.04; P = .04, ≥1 IU/mL threshold). Ordinal logistic regression demonstrated that the odds of a higher repeat quantitative IGRA result increased by almost 2-fold (OR, 1.81; P = .01) per 100 ppm unit increase in median CO2 levels, suggesting a dose-dependent response.
HWs face high occupational TB risk. Increasing median CO2 levels (indicative of poor ventilation and/or high occupancy) were associated with higher likelihood of HW TB infection. Personal ambient CO2 monitoring may help target interventions to decrease TB transmission in healthcare facilities and help HWs self-monitor occupational risk, with implications for other airborne infections including coronavirus disease 2019.
高结核发病率国家的医院存在较高的结核病（TB）传播率，但目前尚无有效的方法来评估医院设计和功能对空气传播感染风险的影响。我们假设个人环境二氧化碳（CO2）监测可以作为衡量与 TB 感染风险相关的再呼吸空气暴露的替代指标，这种暴露与医护人员（HWs）有关。
我们分析了南非开普敦的 138 名 HWs 的基线和重复（12 个月）干扰素-γ释放测定（IGRA）结果。对基线阴性 QuantiFERON Plus（QFT-Plus）的随机 HWs 亚组进行了个人环境 CO2 监测。
TB 感染的年发病率较高（34%）。初级医生的基线 IGRA 阳性率低于其他 HWs（比值比，0.26；P=0.005），但 IGRA 转化率的风险相似。与 IGRA 非转化者相比，IGRA 转化者的 CO2 中位数水平更高，这是使用定量 QFT-Plus 阈值≥0.35 IU/mL（P<0.02）或≥1 IU/mL（P<0.01）的结果。CO2 中位数水平与 IGRA 转化相关（优势比[OR]，2.04；P=0.04，≥1 IU/mL 阈值）。有序逻辑回归表明，CO2 中位数水平每增加 100 ppm 单位，IGRA 重复定量结果更高的可能性几乎增加 2 倍（OR，1.81；P=0.01），提示存在剂量依赖性反应。
HWs 面临较高的职业性 TB 风险。CO2 中位数水平升高（表明通风不良和/或人员密集）与 HWs 结核感染的可能性增加相关。个人环境 CO2 监测可能有助于针对医疗保健设施中的 TB 传播，减少干预措施，并帮助 HWs 自我监测职业风险，这对包括 2019 年冠状病毒病在内的其他空气传播感染具有影响。
