MC LCM U............................................................................................................................................... 1 I. TNH HNH NG C THC PHM TRN TH GII V VIT NAM................................... 2 II. MT S VI SINH VT C TH GY NG C THC PHM .............................................. 6

2.1 Salmonella ...................................................................................................................... 6 2.2 Campylobacter ............................................................................................................... 6 2.3 Clostridium perfringens ................................................................................................. 7 2.4 Clostridium ..................................................................................................................... 7 2.5 Staphylococcus ............................................................................................................... 8 2.6 Vibrio spp ....................................................................................................................... 9 2.7 Escherichia coli ............................................................................................................ 10 2.8 Shigella ......................................................................................................................... 10 2.9 Listeria monocytogenes ................................................................................................ 11 2.10 Cc virus gy bnh trong thc phm ......................................................................... 12 2.11 Coliforms .................................................................................................................... 13 2.12 Nm men v nm mc................................................................................................ 13III. CC PHNG PHP NH LNG VI SINH VT............................................................... 15

3.1 nh lng vi sinh vt bng phng php m trc tip............................................. 15 3.1.1 m bng bung m hng cu ............................................................................ 15 3.1.2 K thut m Breed............................................................................................... 17 3.1.3 m bng knh hin vi hunh quang..................................................................... 18 3.2 Cc k thut nh lng vi sinh vt trong mu bng phng php nui cy............... 19 3.2.1 Phng php m khun lc ................................................................................. 20 3.2.2 Phng php c on s lng vi sinh bng k thut MPN (Most Probable Number): ........................................................................................................................ 28 3.2.3 Phng php lai khun lc .................................................................................... 29 3.3 Phng php o c ................................................................................................ 31IV. P DNG I VI MT S VI SINH VT GY BNH TRONG THC PHM ............... 32

4.1 nh lng Fecal Coliform v E. Coli bng phng php m a ............................ 32 4.2 nh lng Vibrio Parahaemolyticus .......................................................................... 33 4.3 nh lng Coliforms, Coliforms chu nhit, E. Coli gi nh (Fecal Coliforms) bng phng php MPN ............................................................................................................. 35 4.4 nh lng Enterococci ng rut trong nc bng phng php mng lc ........... 37 Thit b: .......................................................................................................................... 37 4.5 nh lng Clostridium kh sunfite trong nc bng phng php tng sinh trong mi trng cy lng................................................................................................................... 38KT LUN ........................................................................................................................................ 40

TI LIU THAM KHO .................................................................................................. 41 PH LC ........................................................................................................................... 42

M UCc vi sinh vt gy bnh nhim trong thc phm thng gp gm cc vi khun Salmonella Shigella, E.coli, Bibrio choterea, Clostridium botulinum, Clostridium perfringens; cc vius Hepatis, virus Hepatis virus A, Rotavirus; cc k sinh trng Amip, sn l gan, sn b, trng lng; cc nm mc v nm men Aspergillus, candida, Furanium... Vi sinh vt gy bnh nhim trong thc phm bng 4 con ng chnh: qua sc vt, qua mi trng, ch bin v bo qun. Mc nguy him v triu chng ca bnh c th gy nn do c t ca vi sinh vt tit vo thc phm hay do chnh t bo ca chng gy nn. c th gy ng c thc phm, vi sinh phi hin din vi s lng t bo ln v ph thuc liu lng ca tng chng loi nhim vo, thc phm phi c cc u kin l ho thch hp cho vi sinh vt pht trin, nhit v thi gian phi thch hp cho qu trnh tng trng ca chng t khi chng nhim vo cho n khi tiu th vi sinh vt nhn ln n liu lng hay sn xut lng c t gy hi. Khi nhim thc phm, vi sinh vt gy h hng lm thc phm b i mu, i v, c mi. Tuy nhin cng c mt s loi gy nhim thc phm nhng khng lm thay i mu, mi, v hay hnh dng bn ngoi ca thc phm. V vy rt kh nhn bit bng cm quan. Do , vic xc nh v nh lng cc vi sinh vt gy bnh nhim trong thc phm l iu rt cn thit.

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I. TNH HNH NG C THC PHM TRN TH GII V VIT NAM cc nc pht trin c ti 10% dn s b ng c thc phm v mc bnh truyn qua thc phm mi nm; vi cc nc km pht trin t l ny cao hn nhiu. Nhiu nc c quy nh bo co nhng ch t 1% s ca b ng c thc phm. Ng c thc phm M chim 5% dn s/nm (>10 triu ngi/nm), trung bnh 175 ca/100.000 dn, mi nm cht 5.000 ngi; Anh: 190 ca/100.000 dn; Nht: 20-40 ca/100.000 dn; c l 4,2 triu ca/nm. Thc trng vi phm v sinh an ton thc phm nc ta rt ng bo ng. Ng c thc phm cp tnh trong nhng nm qua vn c chiu hng gia tng c v s v v quy m mc. T l mc/100.000 dn trung bnh t nm 2001 2005 l 5,48. C nhiu nguyn nhn gy ra cc v ng c thc phm trong ton quc nh thc phm nhim, mi trng nhim; thc phm c c; iu kin sn xut, ch bin thc phm khng bo m an ton, nhn thc hnh vi ng v phng chng ng c thc phm ca cng ng cn nhiu hn ch Trung bnh mi nm c 202.2 v ng c thc phm xy ra vi 5.525,1 ngi mc v 55.2 ngi cht. S v ng c xy ra nhiu nht l t thng 4 - 7 v thng 9 11. T l mc ng c trung bnh l 7.14/100.000 dn, t l cht l 0,06/100.000 dn/nm. S v ng c ln ( 30 ngi) chim 26,8% vi s mc chim 83,2%. V ng c nh v va (