Vedel G
Laboratoire de Bactériologie (Pr Claire Poyart) Groupe Hospitalier Cochin Saint-Vincent-de-Paul La Roche-Guyon, 27, rue du Faubourg Saint-Jacques, 75679 Paris Cedex 14, France.
J Antimicrob Chemother. 2005 Oct;56(4):657-64. doi: 10.1093/jac/dki303. Epub 2005 Sep 6.
Pseudomonas aeruginosa is a major opportunistic bacterial pathogen in nosocomial infections because of the increasing prevalence of resistance to many of the commonly used antibiotics. To ensure optimal efficiency of antibiotic treatment against this species, antibiotic susceptibility tests must be interpreted with caution. Most microbiologists now consider it essential to characterize the antibiotic resistance expressed by isolates. Particular resistance mechanisms may be suspected when the bacterium is resistant to several antibiotics in the same family (for example beta-lactam agents).
Using the disc agar diffusion test, a simple method was developed to distinguish between the common beta-lactam resistance phenotypes of P. aeruginosa and, consequently, the possible resistance mechanism(s). Over a period of 5 years, we analysed 6300 P. aeruginosa strains isolated from various pathological specimens collected from different wards of Cochin Port-Royal Hospital, and reference and collection strains. Each strain had the wild-type phenotype or an acquired resistance phenotype. Eight anti-pseudomonal beta-lactams (ticarcillin, cefotaxime or moxalactam, cefepime or cefpirome, imipenem, ceftazidime, aztreonam, cefsulodin and ticarcillin + clavulanic acid) were used as phenotypic markers.
The following markers were sufficient to distinguish between the wild-type phenotype and the various acquired resistance phenotypes: beta-lactamase synthesis, reduced cell wall permeability and/or increased expression of efflux transporters (active efflux). Detection of resistance phenotypes allows 'interpretive reading' of antibiotic susceptibility tests.
Clearly, improved interpretation of antibiotic susceptibility tests is important for a better appreciation of the effect of antimicrobial agents on bacteria such as P. aeruginosa.
由于对许多常用抗生素的耐药性日益普遍，铜绿假单胞菌是医院感染中主要的机会性细菌病原体。为确保针对该菌种的抗生素治疗具有最佳效果，必须谨慎解读抗生素敏感性试验结果。现在大多数微生物学家认为，对分离株所表现出的抗生素耐药性进行特征描述至关重要。当细菌对同一家族的几种抗生素（例如β-内酰胺类药物）耐药时，可能会怀疑存在特定的耐药机制。
使用纸片琼脂扩散试验，开发了一种简单的方法来区分铜绿假单胞菌常见的β-内酰胺耐药表型，从而确定可能的耐药机制。在5年的时间里，我们分析了从科钦皇家港口医院不同病房收集的各种病理标本中分离出的6300株铜绿假单胞菌菌株，以及参考菌株和保藏菌株。每株菌株都具有野生型表型或获得性耐药表型。使用8种抗假单胞菌β-内酰胺类药物（替卡西林、头孢噻肟或莫西沙星、头孢吡肟或头孢匹罗、亚胺培南、头孢他啶、氨曲南、头孢磺啶和替卡西林+克拉维酸）作为表型标记。
以下标记足以区分野生型表型和各种获得性耐药表型：β-内酰胺酶合成、细胞壁通透性降低和/或外排转运蛋白（主动外排）表达增加。耐药表型的检测有助于对抗生素敏感性试验进行“解读性阅读”。
显然，改进抗生素敏感性试验的解读对于更好地了解抗菌药物对铜绿假单胞菌等细菌的作用非常重要。
