Anaisis Micro de Brotes de Semillas en Noruega

8/14/2019 Anaisis Micro de Brotes de Semillas en Noruega

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Microbiological analysis of seed sprouts in Norway

Lucy J. Robertson a, *, Gro S. Johannessen b, Bjrn K. Gjerde a , Semir Loncarevic b

a Section of Parasitology, Department of Pharmacology, Microbiology and Food Hygiene, The Norwegian School of Veterinary Science, PO Box 8146 Dep., 0033 Oslo, Norway

bSection for Food and Feed Microbiology, National Veterinary Institute, PO Box 8156 Dep., 0033 Oslo, Norway

Received 24 June 2001; accepted 5 November 2001

Abstract

As part of larger survey of microbial contamination of fruits and vegetables in Norway, four different sprouted seed productswere analysed for bacterial and parasitic contaminants ( n = 300 for bacterial analyses and n = from 17 to 171 for parasiteanalyses, depending on parasite). Escherichia coli O157, Salmonella , Listeria monocytogenes , Cyclospora oocysts, Ascariseggs and other helminth parasites were not detected in any of the sprout samples. Thermotolerant coliform bacteria (TCB) wereisolated from approximately 25% of the sprout samples, with the highest percentage of TCB positive samples in alfalfa sprouts.Most TCB were Enterobacter spp. and Klebsiella . E. coli was isolated from 8 of 62 TCB positive mung bean sprout samples.Cryptosporidium oocysts were detected in 8% of the sprout samples and Giardia cysts were detected in 2% of the samples. Allthe Cryptosporidium positive samples, and most of the Giardia positive samples, were mung bean sprouts. Parasite

concentrations in positive samples were low (between 1 and 3 oocysts/cysts per 50 g sprouts). Sprout irrigation water was alsoanalysed for microbial contaminants. E. coli O157 and L. monocytogenes were not detected. TCB were isolated fromapproximately 40% of the water samples. Salmonella reading was isolated from three samples of spent irrigation water on 3consecutive days. Cryptosporidium and Giardia were also isolated from spent irrigation water. Additionally, eight samples of unsprouted mung bean seed were analysed for Cryptosporidium oocysts and Giardia cysts. One or both of these parasites weredetected in six of the unsprouted seed samples at concentrations of between 1 and 5 oocysts/cysts per 100 g unsprouted seed.Whilst our results support spent irrigation water as the most suitable matrix for testing for bacteria, unsprouted seed isconsidered the more useful matrix for analysing for parasite contaminants. D 2002 Elsevier Science B.V. All rights reserved.

Keywords: Alfalfa; Ascaris ; Bean sprouts; Cryptosporidium ; Cyclospora ; Escherichia coli O157; Giardia ; Helminths; Listeria monocytogenes ;Mung; Radish; Parasites; Salmonella ; Seed sprouts; Thermotolerant coliform bacteria; Vegetables

1. Introduction

Consumption of seed sprouts, which has been ubi-quitous for many centuries in oriental culture, has beengrowing in global popularity over the past 30 years. In

the USA, soybean sprouts were heralded as a new andmarvellous form of nutrition during the second worldwar, and since then, increasing interest in eating raw,alternative products has popularised sprout consump-tion yet further. In a US survey in 19981999, of 12,755 people questioned, 976 (7.7%) reported havingeaten alfalfa sprouts during the previous 7 days (C.D.C,1999). Reputedly there are over 450 US-based sprout growers producing over 300,000 tons of sprouts annu-ally to fulfil the consumer demand (Kurtzweil, 1999).

0168-1605/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved.PI I : S0168-1605(01)00738-3

* Corresponding author. Tel.: +47-22-96-49-66; fax: +47-22-96-49-65.

E-mail address: [email protected] (L.J. Robertson).

www.elsevier.com/locate/ijfoodmicroInternational Journal of Food Microbiology 75 (2002) 119126


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Although consumption of seed sprouts has ahealthy image, seed sprouts have been demonstratedto have been the vehicle for transmission in a numberof

foodborne outbreaks of infection. These outbreaks of infection have included salmonellosis and Escherichiacoli O157 infection, and implicated seed sproutsinclude alfalfa, clover, cress, mung bean, radish andsoy. Most of the outbreaks are detailed in a review paper (Taormina et al., 1999), and have occurred inCanada, Denmark, Finland, Japan, Sweden, UK andUS. More recently (2000 and 2001), outbreaks of salmonellosis have been linked to mung bean sproutsin California, USA involving 45 cases (ProMED-mailPost, 2000a) and in Edmonton, Canada, involving over 30 cases (Honish and Nguyen, 2001) and an outbreak of Salmonella enteriditis PT4b infection involving 25cases associated with soya bean sprout consumption inthe Netherlands has been reported (ProMED-mail Post,2000b). Furthermore different unsprouted sesame seed products (tahini and halva) have recently been associ-ated with outbreaks of salmonellosis in Sweden andAustralia (ProMED-mail Post, 2001).

As part of a larger survey of microbial contami-nation of fruits and vegetables in Norway (Robertsonand Gjerde, 2001a), various sprouted seed product samples were analysed for bacterial and parasitic

contaminants. Additionally, water samples used dur-ing the sprout production process and unsproutedseeds were analysed.

The purpose of this study was to determine themicrobiological quality of sprouted seed products onthe Norwegian market, to examine the potential publichealth importance of microbial contamination of seedsprouts, and to investigate the most appropriateapproach for analysing this product for bacteria and parasites.

2. Materials and methods

2.1. Seed sprouts

Alfalfa, mung bean, radish sprouts and sprout mix(including sprouts of green peas, adzuki beans, lentilsand chick peas) were included in the analyses. All had been grown in Norway by the same producer. The threemain distributors of fruit and vegetables in Norwaycollected the samples in rotation and transported the

samples to the laboratory. Bacteriological analysis of the samples was conducted either directly on arrival at the laboratory, or following overnight storage in the

refrigerator. Parasitological analysis was commencedwithin 72 h of arrival of samples at the laboratory. Not all samples were analysed for all bacteria and

parasites. Numbers of samples of produce analysedfor the various bacterial and parasitic contaminants aredescribed in Tables 2 and 3.

2.2. Processing water

Water samples associated with the production of mung bean sprouts were analysed. Altogether 46samples of spent irrigation water were analysed for the presence of bacterial contaminants. Samples weretaken weekly, except for 2 weeks when samples weretaken daily. Approximately 1-l volumes of water weresampled into sterile bottles, transported to the labo-ratory and analysed directly on arrival.

Three water samples were also analysed for Crypto- sporidium oocysts and Giardia cysts. Two 10-l sampleswere of spent irrigation water, and one 10-l sample waswater taken directly from the source, before contact with the sprouting seeds.

2.3. Unsprouted mung bean seeds

Samples of unsprouted mung bean seeds wereobtained from the bean sprout supplier. Eight 100-gsamples were analysed for Cryptosporidium and Giar-dia .

2.4. Bacteriological analysis of sprout and water samples

The sprout and water samples were analysed for the

presence of thermotrophic coliform bacteria (TCB),Salmonella , E. coli O157 and Listeria monocytogenesusing standard methods as listed in Table 1.

2.5. Analysis of sprout samples for Ascaris and other helminths, Cryptosporidium, Giardia and Cyclospora,and analysis of water and seed samples for Crypto- sporidium and Giardia

Development of the methods used in this survey for analysing the sprouts and sprout seeds are described in

L.J. Robertson et al. / International Journal of Food Microbiology 75 (2002) 119126 120


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detail elsewhere (Robertson and Gjerde, 2000; Rob-ertson et al., 2000). In brief, 50-g samples of thesprouts, or 100-g samples of unsprouted seeds, wereweighed into homogeniser bags containing a centralfilter (BagPage, Brevete , France and Etranger) and pro-cessed.

Sample processing consisted of four distinct stages:(a) elution into aqueous suspension, (b) concentration

of suspension, (c) separation of the parasites in thesuspension (for samples analysed for Cryptosporidiumand Giardia and/or Cyclospora ) using paramagnetic beads, and (d) screening by microscopy. The proce-dures are described in greater detail elsewhere (Ro- bertson and Gjerde, in press (a)). For all parasites,appropriate calculations were performed to estimatethe number of parasites in the whole of the sample fromthe number detected in the sub-sample.

The procedure for analysing water samples for Cryptosporidium and Giardia was based upon Method

1623 (Anonymous, 1999b). The analytical techniquecan be divided into 5 distinct sections as follows: (a)membrane filtration of sample, (b) elution of materialfrom membrane filter using detergent solution asdescribed elsewhere (Anonymous, 1997), (c) concen-tration of eluted material by centrifugation, (d) iso-lation of parasites from concentrated eluted material byIMS, and (e) screening by microscopy.

2.6. Recovery efficiency of techniques used for parasitological analysis

Seeding experiments were conducted to assess therecovery efficiency of the techniques used. Details of some of these experiments can be found elsewhere(Robertson and Gjerde, 2001b; Robertson et al., 2000).In brief, 50-g samples of mung bean sprouts, and 100-g samples of unsprouted mung beans, were seededwith appropriate parasites of known concentration, the

Table 1Methods of bacteriological analysis used for samples of sprouted seeds and processing water

Microorganism Analysis Sample type Method or reference method

Thermotolerant coliforms Enumeration Sprouts NMKLa

no. 125. Presumptive colonies cultivated on blood-agar prior to confirmation by gas-production in EC-broth, indole production(BBL k DrySlide k Indole, Becton Dickinson and Company, France)and identification by API 20E (bioMerieux, France). Detection limit 10 cfu/g.

Water NS b 4792. Detection limit 1 cfu/100 ml. E. coli O157 Isolation Sprouts 25 g sample enriched in buffered peptone water (BPW) (225 ml) at

37 F 1 C for 6 hrs prior to immunomagnetic separation (IMS)(according to Dynal) followed by plating on Sorbitol MacConkey agar with cefixime and tellurite (CT-SMAC Oxoid Ltd., England) and Chromagar O157(Chromagar Microbiology, France). Presumptive positive coloniesconfirmed by subcultivation on blood agar, tested for indole-production(DrySlide Indole) and agglutination (drySpot E. coli O157, OxoidLimited, England).

Water NMKL no. 164. 100 ml of water filtered and filter transferred

to 225 ml mTSB with Novobiocin (Difco, USA) and incubated at 41.5 F 0.5 Cfor 6 h prior to IMS. After IMS, samples plated onto Sorbitol MacConkey agar (SMAC Oxoid Ltd., England) and CT-SMAC (containing cefiximeand tellurite). Confirmation performed as described in the NMKL method above.

Salmonella spp. Isolation Sprouts Pre-enrichment and selective enrichment performed as described in NMKL no. 71. A total of 0.1 ml of selective enrichment broth usedfor the ELISA test (Salmonella ELISA test, bioline, Denmark).Presumptive positive samples confirmed according to NMKL no. 71.

Water NMKL no. 71. L. monocytogenes Isolation Sprouts NMKL no. 136. In addition to Oxford and Palcam agar (Oxoid Ltd., England), the samples

also plated on blood-agar.Water NMKL no. 136. Samples plated on Oxford agar only.

a NMKL= Nordic Committee on Food Analysis, 1996, 1999a,b,c. b

NS = Norwegian Standards Association, 1990.



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described method followed and the recovery efficiencycalculated. Although relatively high recovery efficien-cies have been found using these methods from other

vegetables (Robertson and Gjerde, 2000; Robertson et al., 2000) recovery efficiencies from bean sprouts weremore variable and lower, being between approximately25% and 35% for Cryptosporidium , 4% and 42% for Giardia , 38% and 50% for Ascaris and 4% for Cyclo- spora (Robertson and Gjerde, 2000; Robertson et al.,2000). Possible approaches for improving parasiterecovery efficiency from bean sprouts are describedelsewhere (Robertson and Gjerde, 2001c).

Recovery efficiency from mung bean seeds was between 45% and 50% for Cryptosporidium (n = 2)and 65% and 70% for Giardia (n =2).

Recovery efficiency from water samples was approximately 43% for Cryptosporidium and 67% for Giardia (Robertson and Gjerde, 2001b).

3. Analysis of data

Data was compiled in a spreadsheet (Microsoft Excel) and analysed as appropriate using descriptivestatistics, and by construction of contingency tables toenable Chi-squared analysis for association.

4. Results

4.1. Microbiological analysis of seed sprouts

E. coli O157, Salmonella , and L. monocytogeneswere not detected in any of the samples. Thermotoler-

ant coliform bacteria (TCB) were isolated from approximately 25% of the samples of sprouts in varyingnumbers (between 0.2 10 2 and 1.4 10 7 cfu/g)(Table 2). Enterobacter spp. and Klebsiella spp. wereisolated from most of the TCB positive samples. Thestrains were typically identified as E. cloacae , E. saka- zakii and K. pneumoniae ssp. pneumoniae . E. coli wasisolated from eight of the 62 TCB positive mung beansprout samples.

Although a greater percentage of alfalfa sproutswas TCB positive than other sprout types, there was

no statistically significant association between alfalfasprouts and TCB contamination compared to the other sprout types.

Neither Cyclospora oocysts nor Ascaris eggs or other helminth transmission stages were detected onany of the samples. Eighteen (10.5%) of the samplesexamined for Cryptosporidium oocysts and Giardiacysts were found to be positive (Table 3). No sampleswere found to be simultaneously positive for both pa-rasites. Concentrations of Cryptosporidium and Giar-dia detected were generally low (Table 4).

Although all Cryptosporidium positive samples andmost Giardia positive samples were mung bean sprout samples (Table 3), no statistically significant associa-tion between mung bean sprouts and parasite contam-ination was detected as compared to the other sprout types ( p = 0.33).

Only one of the samples that was positive for Cryptosporidium or Giardia was positive for bacterialcontaminants; in this sample of mung bean sprouts, 1Cryptosporidium oocyst/50 g and 1.0 103 cfu/g E.coli were detected .

Table 2Results of bacteriological analyses of seed sprouts

Number (%) samples positive

TCB a

ProduceAlfalfa (n = 27) 8 (30)Mung bean ( n = 259) 62 (24)Radish (n = 6) 0 (0)Sprout mix ( n = 8) 2 (25)Total ( n = 300) 72 (24)

Escherichia coli O157, Salmonella and Listeria monocytogeneswere not detected in any of the samples.

a Thermotrophic coliform bacteria.

Table 3Results of parasitological analyses of sprouted seed samples

Number positive/number analysed. In brackets are% positive samples

Cyclospora Helminths( Ascaris )

Cryptosporidium Giardia

ProduceAlfalfa 0/1 (0) 0/13 (0) 0/16 (0) 0/16 (0)Mung bean 0/16 (0) 0/81 (0) 14/149 (9) 3/149 (2)Radish 0/0 ( ) 0/2 (0) 0/6 (0) 1/6 (17)Total 0/17 (0) 0/96 (0) 14/171 (8) 4/171 (2)

No sample was positive simultaneously for Cryptosporidium andGiardia .



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4.2. Microbiological analysis of processing water

E. coli O157 and L. monocytogenes were not de-tected in any of the 46 samples of spent irrigationwater. TCB were isolated from approximately 40% of the water samples (Table 5). The numbers of TCBvaried from 2 cfu/100 ml to 6.0 105 cfu/100 ml. E.coli was isolated from three, Enterobacter spp. from12 and Klebsiella spp. were isolated from eight of thewater samples. The Enterobacter spp. identified weremostly E. cloacae and the klebsiellas were identified

as K. pneumoniae ssp. pneumoniae .Salmonella reading was detected in three samples of

spent irrigation water from the same batch of sproutson3 consecutive days. Mung bean sprouts from the batchfrom which this contaminated water had been sampledwere unfortunatelynot analysedas a part of this project.Parasites were not detected in the single water sourcesample which had not been in contact with the sprout-

ing seeds. However, parasites were detected in thesamples of spent irrigation water; a single Cryptospori-dium oocyst was detected in one sample and a single

Giardia cyst was detected in the other sample.

4.3. Parasitological analysis of unsprouted mung bean seed

Of the eight 100-g portions of mung bean seedsanalysed, parasites were not detected in two of them.The remaining six all had Cryptosporidium oocystsdetected in them (range = 15 oocysts per 100 g por-tion, mean= 2.3 oocysts, median = 2 oocysts), and of these, Giardia cysts were detected in three portions(one Giardia cyst in each sample).

5. Discussion

The occurrence of TCB in 24% of the sprout samples and 41% of the samples of spent irrigation water could be a warning that pathogens might be present.However, E. coli was only isolated from eight TCB positive sprout samples and three TCB positive spent irrigation water samples. The method used for thedetection of TCB may not be an optimal method for

this type of product. There was a high level of back-ground flora present which may have limited thedetection of indicator bacteria such as E. coli , whichmay have been present at low levels. Most of the TCBstrains isolated belonged to either Enterobacter spp. or Klebsiella spp. These species are normally present inthe environment, and are opportunistic pathogens for humans not usually considered to be of food hygiene

Table 4Concentrations of Cryptosporidium oocysts and Giardia cystsdetected in sprouted seeds

Number of samples (Oo)cysts per 100 g sprouts

Cryptosporidium positive samplesMung bean sprouts 6 2

6 42 6

Giardia positive samplesMung bean sprouts 1 2

1 41 6

Radish sprouts 1 2

Table 5Results of microbiological analyses of processing water used in the production of mung bean sprouts

Number positive Spent irrigation water (1-l volumes) n = 46

Spent irrigation water (10-l volumes) n = 2

Source water (before contact withsprouting seeds;10-l volumes) n = 1

TCB 19 E. coli O157 0 Salmonella 3 L. monocytogenes 0 Cryptosporidium a 1 0Giardia 1 0

a Not examined.



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importance. This suggests that E. coli , rather than TCB,should be used as indicator organism when examiningthe hygienic state of sprouts and other vegetables.

Whilst the only parasites detected in the sproutswere Cryptosporidium oocysts and Giardia cysts, their occurrence was indicative of faecal contamination.However, only one of the samples was simultaneously positive for Cryptosporidium , Giardia and E.coli ; thismay be a reflection of important differences between bacteria and these parasites, particularly the potentialfor amplification and dissemination of bacteria, asopposed to the protozoan parasites, through a produc-tion lot of seed sprouts.

Despite the detection of the human pathogens,Cryptosporidium , Giardia and Salmonella reading ,in the sprouts and water samples, no known cases of infection were associated with contaminated seedsprouts throughout the survey period. For both para-sites and Salmonella , it is possible that if infectionoccurred, it was not always identified or reported or not associated with specific product consumption.Additionally, parasitic infection may not have occurred because the level of contamination was below thehuman infectious dose or because the parasites werenon-viable or non-infectious to humans. No attempt was made to assess viability, infectivity or strain/

isolate of parasite during the survey.The contamination of the sprouts and the spent

irrigation water with bacteria and parasites is probablydue to the use of contaminated seeds (Mahon et al.,1997; Anonymous, 1999a). It has been suggested that contaminated seed has been the source of most, if not all, sprout associated disease outbreaks, and seed isapparently frequently grown, milled and stored inconditions where contamination can occur readily(Anonymous, 1999a). Contamination with pathogenic bacteria may be low, but conditions and processes

during sprouting are ideal for amplifying numbers of Salmonella and E. coli and also for spreading theinfective agent throughout the entire production lot.However, for pathogens such as Cryptosporidium andGiardia, which do not amplify outside their hosts, therisks of adverse public health consequences are con-sidered similar for sprouts to those for other products,or, indeed, less due to the extensive washing duringsprout production (Anonymous, 1999a). However, our survey indicates that sprouts may be contaminatedwith Cryptosporidium oocysts and Giardia cysts, and

the results from analyses of pre-rinse and spent irriga-tion water and also of unsprouted mung bean seedsindicates that seeds are almost certainly the source of

contamination. Regular bacteriological analyses of thewater source used by the sprout production facility(Gro Gjedebo, KNT Gla mdal, pers. comm.) alsoindicate that the seeds, rather than the water, are likelyto have been the source of bacterial contaminants.

The possible routes for seed contamination aredescribed in full elsewhere (Anonymous, 1999a), but the primary reason appears to be that the seedsare treated as a raw agricultural product rather than afood product and may carry microorganisms fromtheir original environment. Indeed, most seed grownis used for agricultural purposes rather than sprouting,and the decision is often not made until post-harvest-ing. The use of manure as a fertiliser, faecally con-taminated water for irrigation, birds, insects, animals,unclean harvesting equipment, storage equipment andtransportation vessels are all factors that should beconsidered when attempting to identify possible con-tamination routes for agricultural products (Beuchat and Ryu, 1997).

Cracks and cavities in the seeds where the pre-sumptive pathogenic bacteria can survive, and even-tually create biofilms (Fett, 2000) and where parasitic

protozoa may adhere, may also be of importance. It isdifficult to remove such contamination, as the forcesholding the pathogens to the seeds are strong, andwould require vigorous cleaning to effect removal.Research has been conducted on approaches for dis-infection of seeds (Delaquis et al., 1999; Taorminaand Beuchat, 1999; Rajkowski and Thayer, 2000;Weissinger and Beuchat, 2000). However, the optimaldisinfection procedure is not obvious, as the methodmust not destroy the seeds capacity to sprout, and the potentially harmful effects of discharge of large vol-

umes of disinfectant must also be considered. Fur-thermore, whereas some disinfection regimes mayeliminate or diminish bacterial survival, it is unlikelyto be effective for Cryptosporidium and Giardia ,which are notoriously robust and can withstand arange of disinfectants.

As well as supplying information on pathogenoccurrence, this study provides useful insights onapproaches to analysing sprouted seeds for pathogens.The results indicate that pathogen testing for sproutedseeds is probably not best conducted on the seed



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sprout produce itself, but on either the spent irrigationwater, or, for parasites, on the unsprouted seeds (Table6). In this survey, the detection rate for TCB washigher from spent irrigation water than in the actual

sprouts. This may be because proportionally larger portions of the sprouts were tested when the spent irrigation water was analysed, as the water runsthrough the whole batch of sprouts before the water is collected. Testing of spent irrigation water for bacterial contaminants is supported by the recently published data of Stewart et al. (2001).

As Cryptosporidium and Giardia do not proliferateoutside their hosts, there is no numerical amplificationadvantage of testing sprouts and/or spent irrigationwater following germination procedures. Indeed, cyst/

oocyst concentrations per unit of matrix (sprout or water) will be reduced, and recovery efficiencies insprouts are also adversely affected. The disadvantageof seed testing is that if contamination is localised (for example a single bag, contaminated in a single cor-ner), then it would be unlikely to be detected in seedtesting, but may be more likely to be detected if spent irrigation water is analysed.

In USA, most sprout growers participate in avoluntary programme of testing spent irrigation water from sprout production for bacterial pathogens (Ano-

nymous, 1999c), and our study supports this regime.However, sprout producers do not routinely test for Cryptosporidium and/or Giardia , and, indeed, to our knowledge, our study is the first to suggest that

sprouted seeds may pose a risk of infection with these protozoan parasites.

6. Conclusion

This Norwegian survey provides information onthe occurrence of pathogens in sprouted seeds, andalso indicates the utility of different approaches for analysis of this product for different pathogens.

Our data indicate the requirement for further re-

search in this area so that the risk of infection withthese pathogens via consumption of sprouted seedmay be more fully understood, and the importanceand most pertinent approach for analysis assessed.

Acknowledgements

This work was supported by a grant from the Norwegian Food Control Authority. We acknowledgethe assistance of KNT Gla mdal, and the ready co-

Table 6Comparison of factors affecting the most appropriate analytical regime for bacterial pathogens and indicators and protozoan pathogens in seedsprouts

Bacterial pathogens and indicators(e.g. E. coli , Salmonella )

Protozoan pathogens (e.g. Giardia cysts,Cryptosporidium oocysts)

Concentration in unsprouted seeds Low; only surviving, unable to proliferate or grow Low; unable to proliferate or growConcentration in seed sprouts High; sprouting provides excellent conditions

(temperature, humidity, nutrition) for resuscitationand proliferation of bacteria

Lower; unable to proliferate or grow1 kg sprout seed may yield between5 to 8 kg sprouts. Losses inirrigation water. Also lower recoveryefficiency of analytical methods

Concentration in spent irrigationwater

High (although may not be as high as in sprouts);sprouting provides excellent conditions(temperature, humidity, nutrition) for resuscitationand proliferation of bacteria

Lower; unable to proliferate or growLarge volumes of water generally usedfor irrigation, particularly of mung bean sprouts

Distribution in unsprouted seeds Probably uneven Probably unevenDistribution in seed sprouts Probably less uneven than in unsprouted

seeds due to mixing, and amplification

Probably less uneven than in unsprouted

seeds due to mixingDistribution in spent irrigation

water Probably less uneven than in unsproutedseeds due to mixing, amplification andwater running through whole production batch

Probably less uneven than in unsproutedseeds due to mixing and water runningthrough whole production batch

In conclusion: preferred matrixfor detection

Spent irrigation water Unsprouted seeds



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operation of the seed sprout supplier. We are gratefulto Andrew Campbell, Microbiology R&D. Dynal AS,OSLO, for provision of the WGA-Dynabeads for iso-

lation of Cyclospora oocysts.

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Anaisis Micro de Brotes de Semillas en Noruega

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