提高甲型副伤寒患者血培养阳性率的研究

A research on improving the proportion of paratyphoid fever A patients with positive blood culture

目的确定甲型副伤寒（简称：甲副）患者血内细菌数及其变化规律，分析血细菌数、采血量、培养分离方法和血培养阳性率间的关系。方法采用定量全血培养技术检测300例临床诊断甲副病例血内细菌数；用标准血培养技术对3000例疑似甲副病例进行需氧和（或）厌氧血培养；用血清甲副病原菌（简称：甲副菌）鞭毛抗原检测的细菌半定量技术分析不同病程215例甲副患者血清甲副菌鞭毛抗原的检测情况。结果131例甲副患者血细菌数的中位数是0．5CFU／ml，全距是〈0．3～6CFU／ml；血细菌数范围为〈0．3、0．3～0．49、0．5～0．9、0．9～4．9和〉5的病例构成分别是22％、28％、33％、12％和5％；长病程甲副患者血清甲副菌鞭毛抗原阳性率比短病程者高（χ^2〉4．06。P〈0．050）；疑似甲副病例5ml和10ml静脉血甲副菌血培养阳性率分别为49．8％和72．8％（χ^2=70．9，P〈0．005）；病例标准需氧瓶和厌氧瓶配对培养总阳性率为51．3％，需、厌氧瓶的血培养结果存在相关关系（χ^2=14．5。P〈0．005），厌氧培养瓶比需氧培养瓶更适合培养血内甲副菌（χ^2=5．0，P〈0．025）。结论甲副病例血内细菌数、采血量、病程、血培养方式是决定血培养阳性率的重要因素，增加采血量和采血次数并用两个以上培养瓶作配对血培养可把甲副患者血培养阳性率提高到接近99％。

Objectives To determine the bacterial counts and its variation in bloods of paratyphoid fever A patients, analyze the relationships among bacterial counts in blood, the volume of blood taken, laboratory methods used for culture and isolation, and the yields from blood cultures. Methods The blood bacterial counts of 300 probable paratyphoid fever A patients were estimated by quantitative whole-blood cultures. Broth blood cultures were per/ormed on 3000 patients with suspected paratyphoid fever A. A semiquantitative method of Salmonella Enterica subsp, enterica set. paratyphoid A on the detection of flagellin antigen in serum was used to analyze the yields from sera flagellin of 215 paratyphoid patients in different duration of illness. Results The median value of S. enterica subsp, enterica set. paratyphoid A count in bloods of 131 paratyphoid fever A patients were 0.5 CFU/ml （range, 0.3 to 6 CFU/ml）. The proportion of paratyphoid fever A patients with bacterial counts in blood 〈0.3, 0.3 to 0.49, 0.5 to 0.9, 0.9 to 4.9 and 〉5 CFU/ml was 22%, 28%, 33%, 12% and 5%, respectively. Cultures were positive for the bacteria in 995 of the 2000 patients （49.8%） when 5 ml of blood was cultured and in 291 of 400 patients （72.8%） when 10 ml of blood was cultured （χ^2 =70. 9,P〈0. 005）. With both aerobic bottles and anaerobic bottles broth culture, the bacteria isolates had been found in the blood of 51.3% of patients with clinically suspected cases of enteric fever. The yields from aerobic and anaerobic broth cultures were of relevant link （χ^2 = 14.5, P〈0.005）, the anaerobic bottles were more suitable for the culture of S. enterica ser. Paratyphoid A in blood than aerobic bottles （χ^2=5.0, P〈0.025）. The positive rate of the bacteria Ilagellin antigen in sera of the patients with long duration of illness was significantly higher than the rate of the patients with short duration of illness （χ^2〉4.06, P〈0.050）, the proportion of paratyphoid fever A patients with the positive sera flagellin antigen was decreased with the increasing duration of illness. Conclusions The bacterial counts in blood, the volume of blood taken, the duration of illness and the blood culture methods used for isolation were important factors determining the yields from blood culture of paratyphoid fever A patients. The proportion of paratyphoid fever A patients with positive blood cultures increases with increasing the volume and bacterial counts of blood taken, as well as two or more blood culture bottles, the positive blood culture rate could come up to 99% or so.