# Current Challenges in _Yersinia_ Diagnosis and Treatment
## 9 Diagnosis  
The diagnostic process should be based on clinical evaluation of the current symptoms. It is worth noting that some symptoms are age-specific. For example, gastrointestinal symptoms usually predominate in children, while in adults, in addition to abdominal symptoms, articular symptoms may predominate. However, yersiniosis can occur in different age groups of patients and is detected both in childhood and in old age. In most cases of infectious diarrhea, _Y. enterocolitia_ is not suspected as a potential source of infection. Therefore, the incidence of yersiniosis is largely underestimated, and \begin{table}
\begin{tabular}{c c c} \hline \hline
\begin{tabular}{c} Severe toxic-allergic syndrome, repeated \\  & cyclically (a cyclic course); \\  & \(\bullet\) & Gastroenteritis, mesadenitis, appendicitisis, \\  & hepatitis, pancreatitis; \\  & \(\bullet\) & Pneumonia, myocarditis, \\  & \(\bullet\) & meningoencephalitis, nephritis; \\  & \(\bullet\) & Scarlet-like form and nodular erythema; \\  & \(\bullet\) & Arthalgia; \\  & \(\bullet\) & Septicemia (lethal outcomes) [3]. \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont_. the difficulty in isolating these pathogens from polycontaminated samples delays the diagnosis [148]. Detection of the organism in a clinical sample is necessary to make a definitive diagnosis of yesriniosis. In clinical practice, isolation of the bacteria from stool, blood, wounds, throat swabs, bile, mesenteric lymph nodes, and cerebrospinal fluid allows for confirmation of the diagnosis [16]. Stool culture is the most readily available method of confirming the diagnosis of _Y. enterocolitica_; however, it should be performed within the first fourteen days of illness. If it is positive, it confirms the infection. Unfortunately, standard stool cultures (without a specific _Y. enterocolitica_ incubation growth medium) do not detect the bacilli of _Y. enterocolitica_ and are laborious [18]. The most sensitive method is a prolonged low-temperature culture on a selective growth medium [148]. Since _Y. enterocolitica_ does not ferment lactose, and is oxidase negative and urease positive, some data suggest direct plating on cefusolodin-irgasan-novobiocin (CIN) agar followed by enrichment procedures according to the reference method ISO 10273:2003 [149]. Unfortunately, even on such a specific medium, _Y. enterocolitica_ is rarely detected. For example, in the analysis of 3622 stool samples, a positive test result was observed in seven samples from five patients [150]. Therefore, culturing on CIN or on other specific media that allow for growth at 25 degrees Celsius is not a cost-effective procedure and should therefore not be routinely used. Another recently described method for detecting Yersinia is the Statens Serum Institut enteric medium (SSI), which allows for the growth of Yersinia at 37 \({}^{\circ}\)C. SSI should not be used to detect _Y. pseudotuberculosis_ because the growth of this bacterium at 37 \({}^{\circ}\)C is inhibited. It is a good method for detecting the pathogenic strains of _Y. enterocolitica_ (most nonpathogenic Yersinia species are inhibited on SSI). However, in contaminated human stool, the recovery of _Y. enterocolitica_ colonies on SSI at 37 \({}^{\circ}\)C is difficult and less sensitive than on CIN at 28 \({}^{\circ}\)C. Therefore, despite its limitations, CIN incubated at 28 \({}^{\circ}\)C is still required for the successful isolation of enteropathogenic Yersinia from stool [148]. The course of the disease varies from mild to aggressive. If the prodromal symptoms predominate, specific serological tests can help to confirm _Yersinia_ infection. These tests are commonly used to detect IgG, IgA, and IgM [151]. Specific antibodies are usually detected in the serum or synovial fluid of patients with the clinical symptoms of yesriniosis using ELISA or immunoblotting. These tests allow for the detection of antibodies against _Yersinia_ LPS, ECA-specific antibodies, and _Yersinia_-specific immune complexes [152].