## 4 Discussion
[47] observed that 15.4% of environmental samples from fish production plants in Finland were contaminated with _L. monocytogenes_. Accordingly, [PERSON] et al. [48] collected samples from the fish-processing environment (floor, sinks, and siphons), equipment (knives and cutting boards), personnel (hands and clothing), and the ice used, with reported isolation rates of 20% for samples from the environment, equipment, and ice, and 5% for the personnel samples. They also reported that the knife and cutting surface samples were the most contaminated environmental samples. In a survey carried out in Thessaloniki, [PERSON] et al. [43] collected 100 samples from the environment, equipment, and workers of fish markets, wherein _Listeria monocytogenes_ was isolated only from the cutting boards, the floor, and the fish storage boxes. In addition to _Listeria monocytogenes_ strains, 98 _Listeria_ spp. isolates were recovered. Specifically, _Listeria_ spp. isolates were detected in 49.6% of environmental samples and 37.0% of fish samples. Similar results were observed by [PERSON] and [PERSON] [49], who reported that the prevalence of _Listeria_ spp. in samples of fresh fish was 40%. However, other studies report lower prevalence rates of _Listeria_ spp. in the fish-processing environment, as well as in fresh fish. [PERSON] et al. [40] reported that _Listeria_ spp. prevalence in the fish-processing environment and in fresh fish was 7.8% and 21.3%, respectively, with _L. innocua_ being isolated at a higher rate (35.3%), similar to the findings of this study. Accordingly, [PERSON] et al. [42] isolated _Listeria_ spp. in 62 of the 470 environmental and fish samples (13.2%) they collected, with most isolated isolates being identified as _L. innocua_. Finally, [PERSON] et al. [50] noted that in the 237 environmental and fish samples collected, the rate for _Listeria_ spp. was 8.86%. Perhaps the complexity of the samples collected in the present study, including quite diverse sampling points, can justify the higher isolation rates. Molecular serotyping of _Listeria monocytogenes_ strains has revealed the most common types to belong to the molecular serotypes IIc (22/24; 91.7%) and IVb (2/24; 83%). Among the relevant publications, there are variations concerning the serotypes isolated from fish and fish-processing facilities. Still, the dominance of molecular serotype IIc is not reported in other studies. [PERSON] et al. [44] reported that most of the isolates from fish and the fish-market environment belonged to serotype 1/2a (45.7%), followed by serotypes 4b (40.3%), 1/2c (5.39%), 1/2b (4.68%), and 4c (3.96%). Also, [PERSON] et al. [40] reported that the 43 _Listeria monocytogenes_ isolates were typed as 1/2a, 4b, and 1/2b, with serotype 1/2a occurring most frequently (72.1%), followed by serotypes 4b (23.3%) and 1/2b (4.7%). [PERSON] and [PERSON] [41] noted that _Listeria monocytogenes_ isolates from fresh fish samples in India belonged to serotypes 4b (66.7%), 1/2b (27.77%) and 1/2a (5.55%). In studies conducted in Israel and China, serotype 4b was the most prevalent serotype [37,51]. In contrast, [PERSON] and [PERSON] [36] reported that among 57 positive isolates, four different serotypes were found, with the most dominant being 1/2a (70.2%), followed by serotypes 1/2b (24.6%), 1/2c (3.5%), and 4b (1.8%). Similarly, in a survey conducted in Turkey, serotype 1/2b was the most frequent in fresh seafood products [52]. In conclusion, serotype 1/2a was reported to be the most frequent serotype among _Listeria monocytogenes_ strains of seafood origin. However, in the present study, none of the _Listeria monocytogenes_ isolates that were collected belong to this serotype; instead, it seems that serotype IIc is persistent in the area of study. In the present study, almost all _Listeria monocytogenes_ strains showed resistance to at least one antimicrobial substance. The highest resistance rates were observed for clindamycin and vancomycin, followed by tetracycline and penicillin.