Rachdi M, Boutiba-ben Boubaker I, Hraoui M, Ben Redjeb S
Laboratory of Microbiology, Charles Nicolle Hospital, Tunis, Tunisia.
Arch Inst Pasteur Tunis. 2010;87(1-2):35-42.
One hundred sixty non duplicate erythromycin resistant Streptococcus agalactiae isolates were collected in Tunisia from January 2005 to December 2007 They were investigated to determine their resistance level to different macrolides and the mechanisms involved. Most erythromycin resistant S. agalactiae isolates were isolated from urinary specimens (38.75%, 62/160). The constitutive MLSB phenotype (cMLS) showed in 84.3% (135/160) with high MICs of macrolides and lincosamides (MIC90>256 microg/mL) and 8.2% (13/160) inducible MLSB phenotype (iMLS) with high MICs of macrolides (MIC90>256 microg/mL) and moderately increased MICs of lincosamides (MIC90=8 microg/mL). The M phenotype showed in 7.5% (12/160) with moderately increased MICs of macrolides (MIC90=32 microg/mL) and low MICs of lincosamides (MIC90=0.75 microg/mL). All strains were susceptible to quinupristun-dalfopristin association and linezolid (MIC90: 05 and 0.38 microg/mL respectively). Strains with MLSB phenotype harboured erm(B) gene with 825% (n=132), erm(TR) gene with 8.12% (n=13) and erm(B) plus mef (A) with 1.88% (n=3). All strains categorized as M phenotype carried the mef(A) gene (75%, n=12). cMLSB phenotype conferring cross resistance to macrolides, lincosamides and streptogramins B with high level of resistance was the most prevalent.
2005年1月至2007年12月期间，在突尼斯收集了160株无重复的耐红霉素无乳链球菌分离株。对它们进行了研究，以确定其对不同大环内酯类药物的耐药水平及相关机制。大多数耐红霉素无乳链球菌分离株来自尿液标本（38.75%，62/160）。组成型MLSB表型（cMLS）在84.3%（135/160）的菌株中出现，其大环内酯类和林可酰胺类药物的最低抑菌浓度（MIC）较高（MIC90>256μg/mL）；诱导型MLSB表型（iMLS）在8.2%（13/160）的菌株中出现，其大环内酯类药物的MIC较高（MIC90>256μg/mL），林可酰胺类药物的MIC中度升高（MIC90=8μg/mL）。M表型在7.5%（12/160）的菌株中出现，其大环内酯类药物的MIC中度升高（MIC90=32μg/mL），林可酰胺类药物的MIC较低（MIC90=0.75μg/mL）。所有菌株对奎奴普丁-达福普汀联合制剂和利奈唑胺敏感（MIC90分别为0.5和0.38μg/mL）。具有MLSB表型的菌株中，82.5%（n=132）携带erm(B)基因，8.12%（n=13）携带erm(TR)基因，1.88%（n=3）携带erm(B)加mef(A)基因。所有归类为M表型的菌株均携带mef(A)基因（75%，n=12）。赋予对大环内酯类、林可酰胺类和链阳菌素B高水平交叉耐药的cMLSB表型最为普遍。
