Peruski L F, Kay B A, El-Yazeed R A, El-Etr S H, Cravioto A, Wierzba T F, Rao M, El-Ghorab N, Shaheen H, Khalil S B, Kamal K, Wasfy M O, Svennerholm A M, Clemens J D, Savarino S J
U.S. Naval Medical Research Unit No. 3, Cairo, Egypt.
J Clin Microbiol. 1999 Sep;37(9):2974-8. doi: 10.1128/JCM.37.9.2974-2978.1999.
No past studies of diarrhea in children of the Middle East have examined in detail the phenotypes of enterotoxigenic Escherichia coli (ETEC) strains, which are important pathogens in this setting. During a prospective study conducted from November 1993 to September 1995 with 242 children under 3 years of age with diarrhea living near Alexandria, Egypt, 125 episodes of diarrhea were positive for ETEC. ETEC strains were available for 98 of these episodes, from which 100 ETEC strains were selected and characterized on the basis of enterotoxins, colonization factors (CFs), and O:H serotypes. Of these representative isolates, 57 produced heat-stable toxin (ST) only, 34 produced heat-labile toxin (LT) only, and 9 produced both LT and ST. Twenty-three ETEC strains expressed a CF, with the specific factors being CF antigen IV (CFA/IV; 10 of 23; 43%), CFA/II (5 of 23; 22%), CFA/I (3 of 23; 13%), PCFO166 (3 of 23; 13%), and CS7 (2 of 23; 9%). No ETEC strains appeared to express CFA/III, CS17, or PCFO159. Among the 100 ETEC strains, 47 O groups and 20 H groups were represented, with 59 O:H serotypes. The most common O serogroups were O159 (13 strains) and O43 (10 strains). O148 and O21 were each detected in five individual strains, O7 and O56 were each detected in four individual strains, O73, O20, O86, and O114 were each detected in three individual strains, and O23, O78, O91, O103, O128, and O132 were each detected in two individual strains. The most common H serogroups were H4 (16 strains), 12 of which were of serogroup O159; H2 (9 strains), all of which were O43; H18 (6 strains); H30 (6 strains); and H28 (5 strains); strains of the last three H serogroups were all O148. Cumulatively, our results suggest a high degree of clonal diversity of disease-associated ETEC strains in this region. As a low percentage of these strains expressed a CF, it remains possible that other adhesins for which we either did not assay or that are as yet undiscovered are prevalent in this region. Our findings point out some potential barriers to effective immunization against ETEC diarrhea in this population and emphasize the need to identify additional protective antigens commonly expressed by ETEC for inclusion in future vaccine candidates.
过去没有针对中东地区儿童腹泻的研究详细检查过产肠毒素大肠杆菌（ETEC）菌株的表型，而在这种情况下ETEC是重要的病原体。在1993年11月至1995年9月对埃及亚历山大港附近242名3岁以下腹泻儿童进行的一项前瞻性研究中，125例腹泻病例的ETEC检测呈阳性。其中98例腹泻病例获得了ETEC菌株，从中选取了100株ETEC菌株，并根据肠毒素、定植因子（CFs）和O:H血清型进行了鉴定。在这些具有代表性的分离株中，57株仅产生耐热毒素（ST），34株仅产生不耐热毒素（LT），9株同时产生LT和ST。23株ETEC菌株表达了一种CF，具体因子为CF抗原IV（CFA/IV；23株中的10株；43%）、CFA/II（23株中的5株；22%）、CFA/I（23株中的3株；13%）、PCFO166（23株中的3株；13%）和CS7（23株中的2株；9%）。没有ETEC菌株似乎表达CFA/III、CS17或PCFO159。在100株ETEC菌株中，代表了47个O群和20个H群，共有59种O:H血清型。最常见的O血清群是O159（13株）和O43（10株）。O148和O21各在5株个体菌株中检测到，O7和O56各在4株个体菌株中检测到，O73、O20、O86和O114各在3株个体菌株中检测到，O23、O78、O91、O103、O128和O132各在2株个体菌株中检测到。最常见的H血清群是H4（16株），其中12株属于O159血清群；H2（9株），均为O43；H18（6株）；H30（6株）；和H28（5株）；后三个H血清群的菌株均为O148。总体而言，我们的结果表明该地区与疾病相关的ETEC菌株具有高度的克隆多样性。由于这些菌株中表达CF的比例较低，我们未检测或尚未发现的其他黏附素在该地区仍有可能普遍存在。我们的研究结果指出了在该人群中有效免疫预防ETEC腹泻的一些潜在障碍，并强调需要鉴定ETEC共同表达的其他保护性抗原，以便纳入未来的候选疫苗中。
