臨床抗生素感受性試驗對於社區性呼吸道感染症治療之重要性

Inferring the Appropriate Empiric Antibiotics to Treat Community-acquired Respiratory Tract Infections According to Clinical Laboratory Data

呼吸道感染症是造成人類最常見的感染症，因此知道那些抗生素適用於治療呼吸道感染症非常重要。本研究企圖分析來自呼吸道所分離的常見菌種及探討其抗藥性，以提供臨床醫師在使用經驗性抗生素治療社區性呼吸道感染症的參考。自2011年至2015年，在南部的某區域醫院，從住院二天內自痰液或咽喉拭子培養出的Streptococcus pneumoniae、Haemophilus influenzae、Haemophilus parainfluenzae及Moraxella catarrhalis皆列入此研究範圍，進行菌株數及抗生素敏感率分析。同時，也分析自2014年10月到12月期間，收集fluoroquinolones、amoxicillin-clavulanate及ceftriaxone經驗性治療社區性肺炎的治療效果，以佐證實驗室的推論是否正確。由273納入研究之菌株中，最常見的菌株為H. influenzae（n =106, 佔38.9%）、H. parainfluenzae（n = 91, 佔33.3%）及S. pneumoniae（n = 59, 佔21.6%）。對於這三種菌株，levofloxacin的敏感率分別為45.3%、41.8%及69.5%；amoxicillin-clavulanate的敏感率分別為72.6%、94.5%及72.7%；ceftriaxone的敏感率分別為99.1%、100%及72.7%。另外，由113納入研究之臨床病例中（包括fluoroquinolones、amoxicilli-clavulanate及ceftriaxolne經驗性治療社區性肺炎的治療效果），ceftriaxone、amoxicillin-clavulanate、fluoroquinolones的治療成功率分別為95.6%（22/23）、81.3%（26/32）及75.9%（44/58）。因此根據此研究的結果（包括最常見致病菌、抗生素敏感率及臨床病例分析），在fluoroquinolones、amoxicilli-clavulanate及ceftriaxolne這三類抗生素當中，能提供治療社區性呼吸道感染症最適當的抗生素是ceftriaxone。在此，我們高度的建議，臨床實驗室應該對於不同的感染症，定期提供最常見的致病菌及抗生素敏感率，以提供臨床醫師在使用經驗性抗生素治療時的參考。如此才能使病患得到較適當的治療，而且我們也認為這種做法是臨床實驗室的責任及義務。

Respiratory tract infections are the most frequent infections in human; hence, a knowledge of antibiotics to treat these infections are very important. This study was conducted to analyze the frequent organisms isolated from respiratory tract and their antimicrobial susceptibility testing, guiding empiric antibiotics prescribed by clinicians to treat community-acquired respiratory tract infections (CA-RTI). At a regional hospital in southern Taiwan, from 2011 to 2015, all positive cultures with Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, and Moraxella catarrhalis isolated from the sputum and throat swab within 2 days hospitalization were enrolled. We analyzed the number of strains and their antimicrobial susceptibility testing results. In addition, from October to December 2015, empiric treatment for community-acquired pneumonia by fluoroquinolones, amoxicillin-clavulante, and ceftriaxone were collected to validate whether our laboratory inferences were correct. A total of 273 isolates were analyzed. The most frequent organisms were H. influenzae (n = 106, 38.9%), H. parainfluenzae (n = 91, 33.3%), and S. pneumoniae (n = 59, 21.6%). For these three organisms, levofloxacin had susceptibility rates of 45.3%, 41.8%, and 69.5%, respectively. Amoxicillin-clavulanate had susceptibility rates of 72.6%, 94.5%, and 72.7%, respectively. Ceftriaxone had susceptibility rates of 99.1%, 100%, and 72.7%, respectively. In addition, we analyzed 113 cases of empiric antibiotics (including fluoroquinolones, amoxicillin- clavulanate, and ceftriaxone) to treat community-acquired pneumonia, finding that the treatment successful rates of ceftriaxone, amoxicillin-clavulanate, and fluoroquinolones were 95.6% (22/23), 81.3% (26/32), and 75.9% (44/58), respectively. According to the results of this study (including analysis of the frequent organisms, in vitro susceptibility testing, and clinical cases), the most optimal antibiotic to treat CA-RTI was ceftriaxone among these three classes of antibiotics. Herein, we highly suggest that the clinical laboratory should offer the frequent organisms and their antimicrobial susceptibility results of different infections on a regular time schedule, guiding empiric antibiotics by clinicians. If so, the patients can get the better treatment; moreover, we think that this is the responsibility of the clinical laboratory.