Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique.
Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal.
BMC Infect Dis. 2020 Sep 7;20(1):659. doi: 10.1186/s12879-020-05380-1.
Diarrheagenic Escherichia coli (DEC) are among the leading pathogens associated with endemic diarrhea in low income countries. Yet, few epidemiological studies have focused the contribution of enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC) and diffusely adherent E. coli (DAEC).
We assessed the contribution of EHEC, EIEC and DAEC isolated from stool samples from a case-control study conducted in children aged < 5 years in Southern Mozambique between December 2007 and November 2012. The isolates were screened by conventional PCR targeting stx1 and stx2 (EHEC), ial and ipaH (EIEC), and daaE (DAEC) genes.
We analyzed 297 samples from cases with less-severe diarrhea (LSD) matched to 297 controls, and 89 samples from cases with moderate-to-severe diarrhea (MSD) matched to 222 controls, collected between November 3, 2011 and November 2, 2012. DEC were more common among LSD cases (2.7%, [8/297] of cases vs. 1.3% [4/297] of controls; p = 0.243]) than in MSD cases (0%, [0/89] of cases vs. 0.4%, [1/222] of controls; p = 1.000). Detailed analysis revealed low frequency of EHEC, DAEC or EIEC and no association with diarrhea in all age strata. Although the low frequency, EIEC was predominant in LSD cases aged 24-59 months (4.1% for cases vs. 0% for controls), followed by DAEC in similar frequency for cases and controls in infants (1.9%) and lastly EHEC from one control. Analysis of a subset of samples from previous period (December 10, 2007 and October 31, 2011) showed high frequency of DEC in controls compared to MSD cases (16.2%, [25/154] vs. 11.9%, [14/118], p = 0.383, respectively). Among these, DAEC predominated, being detected in 7.7% of cases vs. 17.6% of controls aged 24-59 months, followed by EIEC in 7.7% of cases vs. 5.9% of controls for the same age category, although no association was observed. EHEC was detected in one sample from cases and two from controls.
Our data suggests that although EHEC, DAEC and EIEC are less frequent in endemic diarrhea in rural Mozambique, attention should be given to their transmission dynamics (e.g. the role on sporadic or epidemic diarrhea) considering that the role of asymptomatic individuals as source of dissemination remains unknown.
产肠毒性大肠杆菌（DEC）是与低收入国家地方性腹泻相关的主要病原体之一。然而，很少有流行病学研究关注肠出血性大肠杆菌（EHEC）、肠侵袭性大肠杆菌（EIEC）和弥散粘附性大肠杆菌（DAEC）的作用。
我们评估了 2007 年 12 月至 2012 年 11 月在莫桑比克南部年龄<5 岁的儿童中进行的病例对照研究中从粪便样本中分离的 EHEC、EIEC 和 DAEC 的作用。分离株通过针对stx1 和 stx2（EHEC）、ial 和 ipaH（EIEC）和 daaE（DAEC）基因的常规 PCR 进行筛选。
我们分析了 2011 年 11 月 3 日至 2012 年 11 月 2 日期间收集的 89 例中重度腹泻（MSD）病例与 222 例对照以及 297 例轻度腹泻（LSD）病例与 297 例对照的 297 份样本。LSD 病例中 DEC 更为常见（2.7% [8/297]的病例与 1.3% [4/297]的对照；p=0.243]），而 MSD 病例中 DEC 则更为少见（0% [0/89]的病例与 0.4% [1/222]的对照；p=1.000）。详细分析显示，所有年龄组的 EHEC、DAEC 或 EIEC 频率均较低，与腹泻无关联。尽管频率较低，但 EIEC 在 24-59 个月龄的 LSD 病例中更为常见（4.1%的病例与 0%的对照），其次是在婴儿中 DAEC 也有相似的频率（1.9%），最后是对照中有 1 例 EHEC。对前一时期（2007 年 12 月 10 日和 2011 年 10 月 31 日）的样本子集进行分析表明，对照组中 DEC 的频率高于 MSD 病例（16.2% [25/154]与 11.9% [14/118]；p=0.383）。在这些样本中，DAEC 更为常见，24-59 个月龄的病例中为 7.7%，对照组为 17.6%，其次是 EIEC，在 24-59 个月龄的病例中为 7.7%，对照组为 5.9%，但未观察到关联。EHEC 从一个病例样本和两个对照样本中检出。
我们的数据表明，尽管 EHEC、DAEC 和 EIEC 在莫桑比克农村的地方性腹泻中较为少见，但应关注它们的传播动态（例如在散发性或流行性腹泻中的作用），因为无症状个体作为传播源的作用尚不清楚。
