Ispitivanje prisustva i serotipske pripadnosti vrste Streptococcus suis u materijalima poreklom od svinja | Investigation of presence and serotype affiliation of Streptococcus suis species in samples originating from pigs

Cilj ovog ispitivanja je bio da se ustanovi prisustvo S. suis na nekim farmama iklanicama svinja u Republici Srbiji, definišu biohemijske osobine izolovanih sojeva, utvrdinjihova serotipska pripadnost i ispita njihova osetljivost na antibiotike. Poznato je da se S.suis nalazi kao normalan stanovnik respiratornog sistema svinja, najčešće tonzila i nosnihšupljina, a često se može izolovati i iz genitalnog i gastrointestinalnog sistema. Kliničkizdrave svinje predstavljaju glavni rezervoar uzročnika i najznačajniju kariku uepidemiologiji infekcije kod ljudi. Iako se smatra uglavnom patogenom svinja, S. suis je dosada izolovan kao uzročnik infekcija kod različitih drugih vrsta sisara (goveda, mačaka,ovaca) i ptica. Infekcije kod ljudi izazvane S. suis smatrane su sporadičnim i bile suuglavnom vezane za ljude koji dolaze u kontakt sa svinjama i njihovim proizvodima.Međutim, 2005. godine u Kini je izbila epidemija izazvana S. suis kada je obolelo više od 200ljudi, a kod skoro 20% obolelih bolest se završila fatalno. Ova epidemija je potpunopromenila shvatanje o opasnosti ovog patogena za zdravlje ljudi. Veterinarske dijagnostičkelaboratorije obično lako identifikuju S. suis upotrebom malog broja biohemijskih testova,naročito ukoliko su ispitivani uzorci poreklom od obolelih svinja. Međutim, smatra se da nekisojevi (i/ili serotipovi) S. suis mogu biti pogrešno identifikovani komercijalnim kitovima, zbogčega serotipizacija, koja se inače koristi i u rutinskoj dijagnostičkoj proceduri predstavljajednu od sigurnih dijagnostičkih metoda Osetljivost na antibiotike sojeva S. suis u zemljamau kojima je ispitivana uglavnom je zavisila od antibiotika koji su korišćeni u lečenju svinja.Za ovo ispitivanje korišćeni su brisevi nazofaringealnih tonzila prasadi i svinja, nosnihšupljina prasadi, ali i brisevi organa uginule prasadi, brisevi sa trupova zaklanih svinja ibrisevi sa noža za evisceraciju organa na klanici. Svi uzorci su transportovani u tripton sojabujonu u roku od 2 časa od uzorkovanja. Za izolaciju su korišćene čvrste i tečne hranljivepodloge (Columbia agar sa dodatkom 5% ovčije krvi, moždano srčana infuzija sa dodatkom6,5% NaCl, tripton soja bujon, eskulin bujon, andrade ugljeno hidratni bujon sa indikatoromi trehalozom ili salicinom). Za identifikaciju izolovanih bakterija korišćeni su klasični ikomercijalni testovi API 20 Strep i rapid ID32 STREP (bioMérieux, Francuska), a definitivnaidentifikacija sojeva S. suis obavljena je serološkom tipizacijom sa serumima specifičnim zakapsularne antigene (1-35) S. suis, takozvanim Neufeld testom (Quellung reakcija).Ispitivanje osetljivosti sojeva na antimikrobne lekove S. suis izvedeno je disk-difuzionommetodom po Kirby - Bauer-u na Mueller Hinton agaru sa 5% ovčije krvi, korišćenjem diskovaproizvođača BD diagnostics prema uputstvu proizvođača. Od ukupno 226 uzoraka izolovanasu i serotipizirana 34 soja. Serotip 2 S. suis je ustanovljen u 67.7% slučajeva, a serotipovi 7,9 i 1 su izolovani u daleko manjim procentima (17.6%, 8.8% i 5.9%). Kod svih sojevaStreptococcus suis izolovanih od svinja sa nekoliko farmi i klanica u Republici Srbijiustanovljena je visoka osetljivost na cefalosporinske antibiotike, vankomicin i hloramfenikol(100%), manja na penicilin, amoksicilin, ciprofloksacin, eritromicin i azitromicin (94,1%),veoma niska na kombinaciju sulfametoksazola i trimetoprima (5,9%), dok je kod svih sojevautvrđena rezistencija na tetraciklin, klindamicin i linkomicin.

The aim of this study was to establish the presence of S. suis on some pig farms in theRepublic of Serbia, then, to define their biochemical profiles, determine their serotypeaffiliation and test antimicrobial susceptibility of isolated serotypes. It is known that S. suis isa normal inhabitant of the respiratory system of pigs, mostly of the tonsils and nasal cavities,and can often be isolated from the genital and gastrointestinal system. Clinically healthy pigsare a major reservoir of pathogens and the most important link in the epidemiology ofinfection in humans. Although generally considered a pathogen for pigs, S. suis has beenisolated as the cause of infection in a variety of other mammal species (cattle, cats, sheep)and birds. Infections in humans caused by S. suis were considered sporadic and were mostlyrelated to people who come in contact with pigs and their products. However, in year 2005the outbreak in China caused by S. suis affected more than 200 people, with almost 20% ofpatients with the disease ending fatally. This epidemic has completely changed the perceptionof the danger of this pathogen to human health. Veterinary diagnostic laboratories usuallyeasily identify S. suis using a small number of biochemical tests, especially if the samplesoriginate from diseased pigs. However, it is considered that some S. suis strains (and/orserotypes) may be incorrectly identified by commercial kits, thus making serotyping(normally used in routine diagnostic procedures), one of the safest diagnostic procedures.For this test we used nasopharyngeal swabs of pigs and pig tonsils, nasal cavities of piglets,and swabs of dead pigs, swabs from the carcasses of slaughtered pigs and swabs from theevisceration knife after slaughter. All samples were transported in tryptone soy broth within 2hours of sampling. For isolation were used solid and liquid media (Colombia agar with 5%sheep blood added, brain heart infusion with 6.5% NaCl added, tryptone soy broth, esculinbroth, andrade’s carbohydrate broth with indicator and trechalose or salicine). For theidentification of the isolated bacteria classical and commercial tests API 20 Strep and RapidID32 STREP (bioMérieux, France) were used and for the definitive identification of strains ofS. suis serological typing was performed with antisera specific for capsular antigens (1-35)the so-called Neufeld test (Quellung reaction). Antimicrobial susceptibillity testing wasperformed by disc-diffusion (Kirby-Bauer) method on Mueller Hinton agar with 5% sheep bloodusing BD diagnostics antimicrobial susceptibility test discs according to manufacturersinstructions. From 226 collected samples, 34 strains of S. suis have been isolated. S. suisserotype 2 has been isolated in 67,7% of cases, while serotypes 7, 9 and 1 have been isolatedmuch less frequently (17.6%, 8.8% and 5.9%, respectively ). All S. suis strains isolated fromsome pig farms and slaughterhouses in Republic of Serbia showed high antimicrobialsusceptibility to cephalosporins, vancomycin and chloramphenicol (100%), little lesssusceptibility to penicillin, amoxicillin, ciprofloxacin, erythromycin and azythromycin(94,1%), very low susceptibility was observed against sulfamethoxazole and trimethoprim,while all strains were resistant to tetracycline, clindamycin and lincomycin.