Mal Pushpa Bhawan, Jabeen Kauser, Farooqi Joveria, Unemo Magnus, Khan Erum
Section of Pathology and Laboratory Medicine, Clinical Microbiology Aga Khan University, Stadium Road, P.O. Box 3500, Karachi, 74800, Pakistan.
WHO Collaborating Centre for Gonorrhoea and other STIs, Department of Laboratory Medicine, Clinical Microbiology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
BMC Microbiol. 2016 Oct 10;16(1):236. doi: 10.1186/s12866-016-0707-6.
Accurate detection of Neisseria gonorrhoeae antimicrobial resistance is essential for appropriate management and prevention of spread of infection in the community. In this study Calibrated Dichotomous Sensitivity (CDS) and Clinical Laboratory Standards Institute (CLSI) disc diffusion methods were compared with minimum inhibitory concentration (MIC) by Etest in Neisseria gonorrhoeae isolates from Karachi, Pakistan. CDS and CLSI disc diffusion techniques, and Etest for ceftriaxone, penicillin G, spectinomycin and ciprofloxacin against 100 isolates from years 2012-2014 were performed. Due to lack of CLSI breakpoints for azithromycin, it was interpreted using cut-offs from British Society of Antimicrobial Chemotherapy (BSAC). Due to lack of low concentration tetracycline discs, tetracycline was tested with CLSI disc diffusion and Etest only. Comparisons were based on the identified susceptibility, intermediate susceptibility and resistance (SIR) categories using the different methods. Complete percent agreement was percentage agreement achieved when test and reference method had identical SIR-category. Essential percent agreement was percentage agreement when minor discrepancies were disregarded.
There was 100 % and 99 % overall essential agreement and 50 % versus 23 % overall complete agreement by CDS and CLSI methods, respectively, with MICs for all tested antibiotics. Using either method, there was 100 % complete agreement for ceftriaxone and spectinomycin. There was 90 % versus 86 % complete agreement for ciprofloxacin, and 60 % and 75 % for penicillin using CDS and CLSI method, respectively. Essential agreement of 99 % and complete agreement of 62 % was found for tetracycline with CLSI method. There was 100 % essential and complete agreement by CDS, BSAC and Etest for azithromycin.
No major errors with regard to identified SIR-categories were found for penicillin, ciprofloxacin, ceftriaxone and spectinomycin using CLSI and CDS methods. All isolates were susceptible to ceftriaxone and spectinomycin, and 99 % to azithromycin. In low-resource settings, both the CLSI and CDS disc diffusion techniques might be used for susceptibility testing of gonococcal isolates. However, these methods require considerable standardization and quality controls for adequate levels of reproducibility and correct interpretation to reflect appropriately the MIC values of the different antimicrobials. New, emerging, or rare resistance should be confirmed by MIC determination.
准确检测淋病奈瑟菌的抗菌药物耐药性对于社区感染的合理管理和预防传播至关重要。在本研究中，将校准二分敏感度（CDS）和临床实验室标准协会（CLSI）纸片扩散法与Etest测定的最低抑菌浓度（MIC）进行比较，用于检测来自巴基斯坦卡拉奇的淋病奈瑟菌分离株。对2012 - 2014年的100株分离株进行了CDS和CLSI纸片扩散技术以及头孢曲松、青霉素G、壮观霉素和环丙沙星的Etest检测。由于缺乏CLSI阿奇霉素断点，采用英国抗菌化疗协会（BSAC）的临界值进行判读。由于缺乏低浓度四环素纸片，仅用CLSI纸片扩散法和Etest检测四环素。比较基于使用不同方法确定的敏感、中介和耐药（SIR）类别。完全百分比一致性是指测试方法和参考方法具有相同SIR类别时达成的百分比一致性。基本百分比一致性是指忽略微小差异时的百分比一致性。
对于所有测试抗生素的MIC，CDS和CLSI方法的总体基本一致性分别为100%和99%，总体完全一致性分别为50%和23%。使用任何一种方法，头孢曲松和壮观霉素的完全一致性均为100%。环丙沙星的完全一致性分别为90%（CDS法）和86%（CLSI法），青霉素的完全一致性分别为60%（CDS法）和75%（CLSI法）。CLSI法检测四环素的基本一致性为99%，完全一致性为62%。CDS法、BSAC法和Etest法检测阿奇霉素的基本和完全一致性均为100%。
使用CLSI和CDS方法检测青霉素、环丙沙星、头孢曲松和壮观霉素的SIR类别时未发现重大错误。所有分离株对头孢曲松和壮观霉素敏感，对阿奇霉素的敏感率为99%。在资源匮乏地区，CLSI和CDS纸片扩散技术均可用于淋球菌分离株的药敏试验。然而，这些方法需要相当程度的标准化和质量控制，以达到足够的可重复性水平并进行正确判读，从而恰当地反映不同抗菌药物的MIC值。新出现的、罕见的耐药情况应通过MIC测定予以确认。
