Ibrahim Mutasim E, Magzoub Magzoub A, Bilal Naser E, Hamid Mohamed E
Department of Medical Microbiology, Faculty of Medical Laboratory Sciences, Khartoum University, Khartoum, Sudan.
Saudi Med J. 2013 Mar;34(3):240-7.
To analyze integrons gene cassettes Class I among Escherichia coli (E. coli) isolates from Sudan and to determine their effect on the prevalence of resistance to antimicrobials.
This cross-sectional study was conducted at 6 hospitals in Khartoum State, Sudan between April and August 2011. Escherichia coli (n=133) isolated from clinical specimens of patients were included. Isolates were identified and tested for antimicrobial susceptibility following standard procedures. Multi-drug resistance (MDR) patterns was defined as non-susceptibility to ≥3 antimicrobials. Class I integrons was detected by polymerase chain reaction, and gene cassettes were characterized via sequencing analysis.
Of the 133 E. coli isolates, 40.6% (n=54) harbored Class I integrons. All the 54 integron carriage, E. coli was found to be MDR strains. Integron carriage isolates confer higher levels of resistance than any other isolates (p<0.05) such as amoxicillin-clavulanic acid (66.7% versus 36.7%), ceftazidime (46.3% versus 17.7%), chloramphenicol (29.6% versus 7.6%), ciprofloxacin (70.4% versus 43%), tetracycline (88.9% versus 57%) and trimethoprim-sulfamethoxazole (98.1% versus 69.6%). Sequencing of gene cassettes harbored mostly dihydrofolate reductase (dfrA), which encodes resistance to trimethoprim and aminoglycoside adenyltransferase (aadA) that encodes resistance to streptomycin. The most frequent combination types were dfrA17 and aadA5 genes.
Class I integrons were quite common and its carriage contributed significantly to the emergence of MDR among E. coli. Nevertheless, factors leading to the wide spread of integrons are still to be determined.
分析苏丹大肠杆菌分离株中的Ⅰ类整合子基因盒，并确定其对耐药性流行的影响。
本横断面研究于2011年4月至8月在苏丹喀土穆州的6家医院进行。纳入从患者临床标本中分离出的大肠杆菌（n = 133）。按照标准程序对分离株进行鉴定和药敏试验。多重耐药（MDR）模式定义为对≥3种抗菌药物不敏感。通过聚合酶链反应检测Ⅰ类整合子，通过测序分析对基因盒进行表征。
在133株大肠杆菌分离株中，40.6%（n = 54）携带Ⅰ类整合子。在所有54株携带整合子的大肠杆菌中，均发现为多重耐药菌株。携带整合子的分离株比其他任何分离株具有更高水平的耐药性（p<0.05），如阿莫西林 - 克拉维酸（66.7%对36.7%）、头孢他啶（46.3%对17.7%）、氯霉素（29.6%对7.6%）、环丙沙星（70.4%对43%）、四环素（88.9%对57%）和甲氧苄啶 - 磺胺甲恶唑（98.1%对69.6%）。基因盒测序结果大多为编码对甲氧苄啶耐药的二氢叶酸还原酶（dfrA）和编码对链霉素耐药的氨基糖苷腺苷转移酶（aadA）。最常见的组合类型是dfrA17和aadA5基因。
Ⅰ类整合子相当常见，其携带显著促成了大肠杆菌中多重耐药的出现。然而，导致整合子广泛传播的因素仍有待确定。
