The share of Escherichia, especially E. coli, is significant in urinary and gastrointestinal infections (3, 4, and 18). In recent years, E. albertii has been reported to cause gastrointestinal infections in some cases of epidemics, and the results indicated that E. albertii resembles E. coli pathotypes (19, 20). This has challenged a range of studies to verify the diagnosis of E. coli pathotypes, especially EPEC, in recent years. Thus, it was proved that E. albertii was mistakenly identified as EPEC due to its unknown features and similar phenotypic and biochemical characteristics to E. coli (12, 21, and 22). The reliable classification of diarrhea-causing bacteria into distinct pathotypes requires molecular tools, and the unavailability of this equipment in clinical laboratories has led to misdiagnosis and neglect of some pathogens, including E. albertii (22). Recently, researchers, have examined this unknown species in terms of prevalence, biochemical characteristics, pathogenicity, and virulence factors. Although studies in this area are increasing day by day, there is still insufficient information about these indicators in E. albertii.
The study of this bacterial species is of particular importance since some findings have obscured the information from previous research. Therefore, given the importance of E. albertii as a lesser-known bacterial species and its importance in gastrointestinal and urinary tract infections and its neglect in diagnosis, for the first time in Iran (As far as the authors know) the present study identified E. albertii among urinary and fecal samples collected from clinical laboratories in Kermanshah province. These specimens were previously identified as E. coli.
Of the 100 clinical samples, 94 were positive for the uidA gene (Specific for E. coli) and using the specific genes of E. albertii (lysP and mdh), 6 cases (6%) of E. albertii were finally identified. The uidA gene was not found in these six samples. Of the 6 cases of E. albertii, 5 cases belonged to urinary tract infections. It is believed that the origin of E. coli, which causes urinary tract infections, is intestinal flora (23). As a result, the gastrointestinal tract can be the origin of E. albertii identified from urinary samples in the present study.
To identify E. albertii, similar studies have traced two genes of lysP, and mdh. Nimri reported that out of a total of 250 isolates obtained in about ten years from the feces of people with diarrhea, 48 cases of E. albertii were identified using the lysP and mdh genes. The uidA gene was not found in these 48 isolates. It should be noted that these specimens had previously been identified as E. coli (8).
Aoshima also reported 6 E. albertii isolates from 20 phenotypically recognized E. coli samples by identifying the lysP and mdh genes in a population with a gastrointestinal infection of food origin (12).
By tracking the eae gene and sequencing it, Ooka identified 21 out of 31 samples related to the gastrointestinal infection as E. albertii. They were initially diagnosed as E. coli (27). In another study, Ooka reported that out of a total of 278 samples from the human, animal, and environmental sources previously identified as E. coli using common diagnostic methods, 26 were identified as E. albertii using MLST analysis of the eae gene. 14 cases of them belonged to human samples (21).
Hinenoya re-examined 20 strains of E. coli isolated from diarrheal infections. He identified all 20 isolates as E. albertii by MLST analysis of housekeeping genes of E. albertii (24).
Ori et al., in a 6-year care program re-examined diarrhea-causing E. coli isolates. They identified 10 E. albertii cases out of a total of 693 isolates by tracking specific genes including cdgR, DNA-binding transcription activating gene in cysteine biosynthesis, and palmitoyl-acyl carrier protein-depended acetyltransferase gene (22).
In a research conducted by Lindsey, out of a total of 1,644 samples of chicken carcasses over one year at the slaughterhouse, lysP and mdh genes were positive in 61 isolates, which were identified as possible E. albertii species. However, the sequencing of the rpoB gene reduced the number of E. albertii to 27 (14).
In general, due to the lack of a specific diagnostic protocol for E. albertii, different studies have used different methods and specific genes to identify it, and this information is constantly changing. It can be argued that although most studies have identified the two genes of lysP and mdh as specific genes in the diagnosis of E. albertii, in several studies these two genes have not been able to identify all E. albertii. Therefore, efforts have been made to design more specific areas of the genome (10, 13–15).
Also, there is a discrepancy in the findings of the phenotypic and biochemical characteristics of E. albertii. For example, E. albertii was previously considered as a type of negative lactose, but a recent study found that strains of E. albertii could ferment the lactose (26). One of the reasons for the limited recognition of the phenotypic and biochemical properties of E. albertii is the small number of known strains to date (14).
In general, there is no sufficient information about the features of E. albertii to isolate and diagnose it optimally. As a result, it is difficult to identify the true prevalence of infections associated with E. albertii (24).
In several studies, the role of E. albertii as a potential and related pathogen in cases of gastroenteritis and diarrhea in humans has been confirmed (14 and 25–30). In countries such as Japan and Norway, the number of infections caused by E. albertii is increasing, which is a warning sign that the bacterium is causing problems around the world (24).
E. albertii is important not only for its pathogenicity and its role in gastroenteritis in the world but also for its resistance to certain antibiotics (6, 7). Therefore, it is important to continuously examine patients with diarrhea and urinary tract infections to detect E. albertii. Deaths among birds are another reason for global attention to E. albertii. The bacterium has also been isolated from animals such as pigs, cats, and in some cases from environmental and food contamination (21, 31–33, 98–100). As a result, epidemiological studies should include not only the clinical level but also animal and environmental patterns such as water and food.
In the first step, the study of the frequency of E. albertii in the world can help further identify it. Epidemiological studies also help identify pathogenic strains, biochemical characteristics, and virulence genes. Finally, the integration of data and results leads to a comprehensive and accurate definition of the characteristics of E. albertii. In general, it can be said that in the future, diagnostic tests for E. albertii will be routinely performed in clinical laboratories to differentiate it from other members of the Enterobacteriaceae family.