Prevalence of psychrotrophic pathogens and hygiene indicators in fish in eutrophic lakes and retail in Latvia. Summary of the Doctoral thesis for the scientific degree of Dr.med.vet. | Psihrotrofo patogēnu un higiēnas indikatormikroorganismu izplatība zivīs eitrofos ezeros un mazumtirdzniecībā Latvijā. Promocijas darba kopsavilkums Dr.med.vet. zinātniskā grāda iegūšanai

anglais. Salmonella spp., Listeria monocytogenes and Yersinia enterocolitica are the most commonly reported foodborne pathogens, and it can be transmitted to humans through raw or undercooked food. The purpose of this study was to investigate the prevalence of Salmonella spp., Listeria monocytogenes, Yersinia enterocolitica and hygiene indicators in raw fish from lakes and at retail. Overall, 194 raw fish samples were analysed in this study. The fish samples were collected from three eutrophic lakes and at retail in Latvia during the period of June to December 2014. Hygiene indicators were detected on skin, gills, and in gut of each fish. The prevalence of pathogens were studied in subsample of fish musscle, skin and internal organs. The various hygiene indicators, total bacterial count, Enterobacteriaceae count, fecal coliforms, psychrotrophs, and Escherichia coli were determined. Fish samples were analysed for the presence of pathogenic bacteria, Salmonella spp., L. monocytogenes and Y. enterocolitica. Hygienic indicators and presence of pathogens were determined according to ISO methods. PCR serogrouping method was used to examine strains of L. monocytogenes isolated from fish. For isolates identified as Y. enterocolitica biotype was detected by biochemical reactions. Among 135 fish samples from retail investigated, Listeria monocytogenes were isolated from 35 (26%) samples, and Y. enterocolitica from 45 (33%) samples. L. monocytogenes serogroup IIa was predominant, followed by IIb and IVb. All of isolated Y. enterocolitica strains belonged to biotype 1A. Salmonella spp. were not detected in any of fish samples analysed. No pathogens were detected in fish samples collected from lakes. Salmonella spp., L. monocytogenes and Y. enterocolitica are a major public health concern.

letton. Psihrotrofās patogēnās baktērijas spēj saglabāt dzīvotspēju un augt temperatūrā, kas zemāka par 7 ºC. Pie psihrotrofajām baktērijām pieder Listeria monocytogenes un Yersinia enterocolitica, un tās ir vienas no biežāk konstatētajām pārtikas infekciju ierosinātājām cilvēkiem Eiropas Savienībā (EFSA, 2016; EFSA, 2013). Pētījuma materiāls ievākts trīs ezeros un vienā mazumtirdzniecības uzņēmumā Latvijā. Kopumā tika ievākti 194 zivju paraugi, kas piederēja desmit zivju sugām. Higiēnas indikatormikroorganismi tika noteikti trīs dažādos audos katram zivju paraugam, bet patogēnu sastopamība analizēta katrā zivī. No higiēnas indikatormikroorganismiem tika noteikts baktēriju kopskaits, Enterobacteriaceae dzimtas baktērijas, fekālās koliformas, psihrotrofie mikroorganismi un Escherichia coli. Higiēnas indikatormikroorganismu un patogēnu noteikšanai tika pielietotas metodes, kas atbilst ISO standartiem. Listeria monocytogenes izolēšanas gadījumā veikta izolātu serogrupu noteikšana ar multiplex PCR metodi. Yersinia enterocolitica izolēšanas gadījumā tika noteikts biotips, pielietojot bioķīmiskās reakcijas. Konstatēts, ka zivīs mazumtirdzniecībā sastopami Listeria spp., tostarp L. monocytogenes celmi, kā arī Yersinia spp., tostarp Y. enterocolitica celmi. Zivīs no ezeriem Listeria spp., Yersinia spp. un Salmonella nebija sastopamas. Zivīs mazumtirdzniecībā netika konstatētas Salmonella ģints baktērijas. Higiēnas indikatormikroorganismu izplatība bija atšķirīga dažādos audos zivīs no ezeriem, kā arī zivīs mazumtirdzniecībā. No ezeru zivīm viszemākais higiēnas indikatormikroorganismu daudzums bija zušos.