Isihloko
I-EMB agar iqhathaniswa ne-MacConkey agar: ukukhetha nokuhumusha imidiya
Umfundi uhlikihla isampula yamanzi efanayo emapuletini amabili. Kwelinye, kuvela amakoloni amnyama anokucwebezela okuluhlaza okufana nensimbi. Kwelinye, kuvela amakoloni aphinki agqamile anendilinga efiphele ewazungezile. Womabili amapuleti afakwe isampula evela kushubhu elifanayo, afukanyelwa eceleni komunye nomunye, futhi afundwa ngehora elifanayo. Umfundi ubuza ukuthi yiliphi ipuleti elilungile.
Womabili amapuleti alungile. Aphendula imibuzo ehlukene. Ukudideka kuvela lapho le midiya emibili iphathwa njengezindlela ezishintshanayo zokuhlola amagciwane asemathunjini. Inenhloso efanayo, okuwukukhetha izinhlobo ze-enteric eziyi-Gram negative nokuhlukanisa ama-lactose fermenter kuma-nonfermenter, kodwa leyo nhloso iyifeza ngekhemistri ehlukene nangendlela ehlukene yokuchaza okubonakalayo. Uma usuqonda imiqondo emibili eyisisekelo, ukukhetha ipuleti nokufunda amakoloni kuba umsebenzi ojwayelekile.
Impendulo emfushane
I-EMB agar isebenzisa odayi ababili, i-eosin Y ne-methylene blue, abenza imisebenzi emibili: banciphisa ukukhula kwe-Gram positive futhi babumbane bazinze eduze kwabakhiqizi be-asidi enamandla ukuze bakhe amakoloni amnyama, ngokwesibonelo avame ukuba nokucwebezela okuluhlaza okufana nensimbi ku-Escherichia coli. I-MacConkey agar ihlukanisa le misebenzi: ama-bile salts kanye ne-crystal violet kunciphisa ama-Gram positive, i-lactose isekela i-fermentation, kanti i-neutral red ibonisa i-asidi ngokwenza amakoloni abe phinki noma abomvu. Uma umsebenzi uwukubonisa ngendlela ecacile okusolakala ukuthi yi-E. coli, i-EMB iyafaneleka. Uma umsebenzi uwukuhlukanisa ngokucacile ama-lactose fermenter aphinki kuma-nonfermenter angenambala, ikakhulukazi ezinqubweni zesitulo noma zomchamo, i-MacConkey ngokuvamile kulula ukuyifunda. Alikho ipuleti elikhomba uhlobo lwesidalwa ngombala kuphela.
EMB: odayi abakhetha futhi babike ngesikhathi esisodwa
Umqondo we-EMB uhlanganisa ukukhetha nokukhombisa kuma-molecule afanayo. I-ASM eosin methylene blue agar protocol ichaza i-EMB njengemidiya ekhethayo nehlukanisayo, lapho inhlanganisela yodayi ivimbela izinhlobo eziningi ze-Gram positive kuyilapho i-lactose fermentation ibangela ukuthathwa nokuzinza kodayi. I-Levine formulation ejwayelekile iqukethe i-peptone, i-lactose, i-phosphate, i-eosin Y, i-methylene blue, ne-agar, njengoba kubhalwe ku-FDA BAM method for Levine EMB agar. Qaphela ukuthi amaresiphi amadala e-EMB kwesinye isikhathi ayefaka i-sucrose kanye ne-lactose, kuyilapho i-Levine EMB iqukethe i-lactose ngaphandle kwe-sucrose, ngakho bhala ukuthi iyiphi formulation esetshenziswa ilabhorethri yakho.
Ukufunda i-EMB kusho ukufunda ukuziphatha kodayi. I-lactose fermentation enamandla ikhiqiza i-asidi eyanele ukubangela ukuzinza okukhulu kodayi, okwenza i-E. coli ibe nezikhungo ezimnyama eziluhlaza okwesibhakabhaka kuya kokumnyama futhi, esimweni sakudala, ibe nokucwebezela okuluhlaza okufana nensimbi ekukhanyeni okubuyiselwe. Ama-fermenter abuthakathaka njenge-Enterobacter ne-Klebsiella ngokuvamile akhula njengamakoloni aphinki kuya kokunsomi, ane-mucoid, ngaphandle kwalokho kucwebezela. Ama-nonfermenter afana ne-Salmonella, Shigella, ne-Proteus ngokuvamile akhula njengamakoloni angenambala noma acishe abonakale ngoba awakhiqizi ukuqhuma kwe-asidi okubangela ukuzinza kodayi. Ama-Gram positive ngokuvamile ayacindezelwa, nakuba izinga lokucindezelwa lingafani futhi lishintsha ngohlobo lwe-strain nomkhiqizo. Ikhemistri ephelele yokulungiselela odayi, okuhlanganisa nokuthi kungani i-methylene blue iziphatha njenge-cationic stain kwasekuqaleni, ingeyengxoxo ehlukile mayelana nama-dye formulation, kanti umongo ojwayelekile we-microscopy utholakala ku-atlas yezindlela zokufaka umbala. Lesi sihloko sigxile ekukhethweni nasekufundweni kwamapuleti.
Umfanekiso ongenhla uyisibonelo sokuchaza. Ubonisa indlela yokucabanga ngokubonakalayo okufanele uyilindele: amakoloni amnyama acwebezelayo kanye nezinhlobo eziphinki ezine-mucoid kanye nezinhlobo eziphaphathekile ku-EMB, kuqhathaniswa nezinhlobo eziphinki neziphaphathekile ku-MacConkey. Wusebenzise ukufunda iphethini, bese uqinisekisa konke okufundayo ngezithombe zama-control kanye ne-product insert yemidiya ngqo esebhentshini lakho.
MacConkey: imisebenzi ehlukanisiwe, umthetho wokubona olula
Umqondo we-MacConkey unikeza umsebenzi ngamunye isithako esihlukile. I-ASM MacConkey agar protocol iveza indlela efanayo yokuthi iyakhetha futhi iyahlukanisa, kanti i-FDA BAM method for MacConkey agar ibala izingxenye ezisebenzayo: ama-peptone, i-lactose, ama-bile salts, usawoti, i-neutral red, i-crystal violet, ne-agar. Ama-bile salts kanye ne-crystal violet kukhetha ngokumelene nama-Gram positive. I-lactose ihlinzeka nge-substrate ye-fermentation. I-neutral red isebenza njengombiki we-pH, ishintshe ibe phinki kuya kobomvu lapho kwakheka khona i-asidi, kwesinye isikhathi kube ne-bile ezinzile ezungeze ama-fermenter anamandla.
Umthetho wokufunda wenziwe waba lula ngamabomu: ophinki kusho i-lactose fermenter, ongenambala noma ophaphathekile kusho i-nonfermenter. I-E. coli ibonakala iphinki kuya kobomvu, ngokuvamile ibe nendilinga ye-bile precipitate. I-Klebsiella ne-Enterobacter ibonakala iphinki futhi ivame ukuba ne-mucoid ngenxa yama-capsule ayo. I-Salmonella, Shigella, Proteus, kanye nezinye izinduku eziningi ze-Gram negative zibonakala zingenambala. Kunenye inzuzo ebalulekile kumalabhorethri okufundisa: ama-bile salts ngokuvamile anciphisa i-Proteus swarming, ngakho kulula ukuthola amakoloni ahlukene ku-MacConkey kunasemidiyeni engakhethi, nakuba ukucindezelwa kungaphelele futhi kunezinye izindlela ezingenawo usawoti lapho ukulawula i-swarming kuyinto ebaluleke kakhulu.
Isizathu samangqamuzana sokuthi odayi baziphathe ngale ndlela sibuyela ekushajeni nasekwakhekeni. I-Methylene blue ingudayi we-cationic phenothiazine, futhi ukwakheka nezakhiwo zayo kuchaza ukuthambekela kwayo ezindaweni zamagciwane ezine-asidi, okuwukuthambekela okufanayo okusebenza lapho izinzile ezindaweni ezine-asidi ku-EMB.
Ukuqhathanisa ngokushesha
| Isici | EMB agar | MacConkey agar |
|---|---|---|
| Uhlelo lokukhetha | Eosin Y plus methylene blue | Bile salts plus crystal violet |
| I-substrate yokuhlukanisa | Lactose (Levine has no sucrose) | Lactose |
| Inkomba | Dye precipitation itself (dark colonies, green sheen) | Neutral red (pink to red acid colonies) |
| Strong E. coli signal | Dark blue black colony, often metallic green sheen | Pink to red colony, often bile precipitate |
| Klebsiella and Enterobacter | Pink to purple, mucoid, usually no sheen | Pink to red, often mucoid |
| Salmonella, Shigella, Proteus | Usually colorless or translucent | Usually colorless or pale |
| Gram positives | Usually suppressed | Usually suppressed on crystal violet formulas |
| Best teaching payoff | Strong versus weak fermentation made visible | Simplest fermenter versus nonfermenter sort |
Funda ithebula njengenqubo yokwenza isinqumo. Lapho umsebenzi udinga abafundi babone ibanga lamandla e-fermentation elinesiphetho esisodwa esivelele, i-EMB iyakubonisa. Lapho umsebenzi udinga ukuhlukaniswa okusheshayo okubili ngaphambi kokuqinisekiswa nge-biochemical, i-MacConkey iyakubonisa.
Iyiphi imidiya yesampula ngayinye
Emisebenzini yamanzi egxile ekuqaphelweni okusolwayo kwe-fecal coliform noma i-E. coli, i-EMB iyakhanga ngoba ukucwebezela kwayo kuhluke ngokubonakalayo. I-MacConkey nayo isebenza kuma-enteric Gram negative futhi inomlando wokusetshenziswa emanzini, kodwa alikho ipuleti elithatha indawo yendlela yokuhlola amanzi ebekwe ngumthetho, engase icacise imidiya efana ne-modified mTEC noma MI kuye ngokuhlolwa. Hlola indlela ilabhorethri yakho ephoqelekile ukuyilandela.
Ekuhlukaniseni okufana nokwenziwa kumasampula esitulo phakathi kwama-fermenter nama-nonfermenter, i-MacConkey ngokuvamile iwusizo kakhulu kulezi ezimbili. Umsebenzi wesitulo osebenzayo we-Salmonella noma Shigella ngokuvamile ungeza imidiya ye-enteric ekhethayo kakhulu njenge-XLD noma Hektoen enteric kunokuthembela ku-MacConkey kuphela.
Ekufundiseni ngesampula yomchamo okulingisa ukuhamba komsebenzi kwe-clinical, hlanganisa i-MacConkey ne-blood agar. I-MacConkey ihlinzeka ngokuhlukaniswa kokuqala kwama-Gram negative kuyilapho i-blood agar ikhuphula izinhlobo ezicindezelwa yi-MacConkey. Lokhu kubhangqa kujwayelekile ezincazelweni ze-clinical zokulungiselela i-urine culture.
Ekufundiseni umqondo ngokumsulwa, sebenzisa kokubili. I-EMB ifundisa ukuthi amandla e-fermentation abalulekile nokuthi i-molecule eyodwa ingenza imisebenzi emibili. I-MacConkey ifundisa ukwakheka okuhlukaniswe ngamamojula: umkhethi, i-substrate, nombiki kugcinwa kuhlukene. Abafundi abahlakaza i-E. coli eyaziwayo, i-Klebsiella aerogenes eyaziwayo, kanye ne-Salmonella eyaziwayo eceleni komunye nomunye kuwo womabili amamidiya ngokuvamile abasaphambanisi lezi zindlela ezimbili zokucabanga.
Izingibe zokufunda eziphindaphindeka njalo ngethemu
Ukwehluleka okuvame kakhulu ukukhomba uhlobo ngombala kuphela. Ophinki ku-MacConkey kungaba yi-E. coli, Klebsiella, Enterobacter, noma enye i-fermenter. Ongenambala kungaba yi-Salmonella, Shigella, Proteus, Pseudomonas, noma enye i-nonfermenter. Umbala uyisici sokuhlola esiqondisa umsebenzi wokuqinisekisa njenge-Gram stain, oxidase, biochemical panels, noma ukuhlonza ngethuluzi, hhayi igama lohlobo.
Ukwehluleka kwesibili ukuchaza ngokweqile ukungabikho kokucwebezela. Amanye amakoloni e-E. coli angempela, ikakhulukazi ahlukaniswe kahle, akhiqiza ukucwebezela okuncane noma angakhiqizi nhlobo ku-EMB. Ukungabikho kokucwebezela akuyikhiphi i-E. coli, futhi ukuba khona kwakho akuyifakazeli. Phatha ukucwebezela njengenkomba esolwayo.
Ukwehluleka kwesithathu ukuqhathanisa amapuleti aneminyaka ehlukene. Ama-lactose fermenter abambezelekile angaphenduka aphinki ku-MacConkey ngemva kokufukanyelwa isikhathi eside, okwenza ukuhlukaniswa okucacile phakathi kwe-fermenter ne-nonfermenter kungabe kusacaca. Funda ngehora elishiwo ilabhorethri futhi ubhale isikhathi sokufukanyelwa kanye nomphumela.
Ukwehluleka kwesine ukufunda ukukhula okuxubile njengohlobo olulodwa. Ikoloni ephinki eduze kwekoloni engenambala imelela ama-phenotype amabili, hhayi into ephakathi. Khetha amakoloni ahlukene kahle futhi usebenze nge-morphotype ngayinye ngokwehlukana. Ukuthungwa kwe-mucoid kwengeza ingibe efanayo: kokubili i-Klebsiella ne-Enterobacter kungabonakala kune-mucoid, ngakho i-capsule iyodwa ayikwazi ukunquma igama. Isidalwa esasifundiswa njenge-Enterobacter aerogenes manje sesihlukaniswa njenge-Klebsiella aerogenes, okuchaza ukuthi kungani amashadi amadala namalebula amasha kubonakala kungavumelani.
Ama-control nomthetho wokugcina
Sebenzisa ama-control anezithombe noma amasha njalo ngeseshini: i-E. coli yokusabela kwe-fermenter enamandla, i-Klebsiella aerogenes ye-mucoid fermentation ngaphandle kokucwebezela okujwayelekile, i-Salmonella strain yokusabela kwe-nonfermenter engenambala, kanye ne-Staphylococcus aureus ukuqinisekisa ukucindezelwa kwe-Gram positive kumkhiqizo wakho ngqo. Qondanisa izinombolo zama-strain nemibandela yokwamukelwa ne-manufacturer insert, ngoba ukukhetha kuyashintsha ngokwe-bile, crystal violet, nokuqukethwe kodayi.
Khumbula umusho owodwa ebhentshini. I-EMB isebenzisa odayi abakhetha futhi babike ngesikhathi esisodwa, okunikeza uphawu lwe-E. coli olugqamile kodwa kudinga ukufunda okucashile kakhudlwana. I-MacConkey ihlukanisa ukukhetha nokubika, okunikeza ukuhlukaniswa okulula phakathi kokuphinki nokuphaphathekile kodwa kunikeza imininingwane encane ngamandla e-fermentation. Khetha imidiya enomqondo ohambisana nombuzo, qinisekisa umbala ngezivivinyo ezifanele, bese la mapuleti amabili eyeka ukuncintisana aqale ukusebenzisana.