From the Research
The pleomorphic nature and bipolar staining pattern of Yersinia enterocolitica are crucial for its identification and have significant implications for diagnosis and treatment of infections, as they can lead to misdiagnosis if not properly recognized. These morphological characteristics help laboratory personnel identify the organism during microscopic examination, with the bacteria appearing as either short rods or coccobacilli with distinctive bipolar staining (giving a "safety pin" appearance) when special stains like Wayson or Giemsa are used 1. The pleomorphism is more pronounced at lower temperatures (22-25°C) than at body temperature (37°C), which is important when culturing clinical specimens. For proper isolation, selective media like CIN agar (cefsulodin-irgasan-novobiocin) should be used and incubated at both 25°C and 37°C for 24-48 hours.
Some key points to consider:
- The organism's adaptability to different environments contributes to its virulence and ability to cause various clinical syndromes ranging from gastroenteritis to pseudoappendicular syndrome and, in rare cases, septicemia in immunocompromised patients or those with iron overload conditions 1.
- The identification of Yersinia enterocolitica can be achieved through Fourier transform infrared spectroscopy, which allows for differentiation at the species and subspecies levels, including the presence or absence of the ail gene, a main pathogenicity marker 2.
- Antimicrobial susceptibility tests have shown that aminoglycosides and co-trimoxazole are effective against Yersinia enterocolitica, while the organism is resistant to ampicillin, carbenicillin, cloxacillin, and erythromycin 3.
Given the potential for misdiagnosis and the importance of proper identification for effective treatment, it is essential to consider the pleomorphic nature and bipolar staining pattern of Yersinia enterocolitica in clinical practice, particularly when culturing clinical specimens and selecting appropriate antimicrobial therapy 1, 2, 3.