Chlorine Resistance of Listeria monocytogenes Biofilms and Relationship to Subtype, Cell Density, and Planktonic Cell Chlorine Resistance

Strains of Listeria monocytogenes vary in their ability to produce biofilms. This research determined if cell density, planktonic chlorine resistance, or subtype are associated with the resistance of L. monocytogenes biofilms to chlorine. Thirteen strains of L. monocytogenes were selected for this research based on biofilm accumulation on stainless steel and rep-PCR subtyping. These strains were challenged with chlorine to determine the resistance of individual strains of L. monocytogenes. Planktonic cells were exposed to 20 to 80 ppm sodium hypochlorite in 20 ppm increments for 5 min in triplicate per replication, and the experiment was replicated three times. The number of tubes with surviving L. monocytogenes was recorded for each isolate at each level of chlorine. Biofilms of each strain were grown on stainless steel coupons. The biofilms were exposed 60 ppm of sodium hypochlorite. When in planktonic culture, four strains were able to survive exposure to 40 ppm of chlorine, whereas four strains were able to survive 80 ppm of chlorine in at least one of three tubes. The remaining five strains survived exposure to 60 ppm of chlorine. Biofilms of 11 strains survived exposure to 60 ppm of chlorine. No association of biofilm chlorine resistance and planktonic chlorine resistance was observed; however, biofilm chorine resistance was similar for strains of the same subtype. Biofilm cell density was not associated with chlorine resistance. In addition, biofilms that survived chlorine treatment exhibited different biofilm morphologies. These data suggest that chlorine resistance mechanisms of planktonic cells and biofilms differ, with planktonic chlorine resistance being more affected by inducible traits, and biofilm chlorine resistance being more affected by traits not determined in this study.

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Destruction of Listeria monocytogenes by Sodium Hypochlorite and Quaternary Ammonium Sanitizers

Journal of Food Protection ◽

10.4315/0362-028x-52.5.306 ◽

1989 ◽

Vol 52 (5) ◽

pp. 306-311 ◽

Cited By ~ 69

Author(s):

A. MUSTAPHA ◽

M. B. LIEWEN

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Sodium Hypochlorite ◽

Quaternary Ammonium ◽

Ammonium Compound ◽

Electron Microscopic ◽

Acidic Polysaccharide ◽

Scanning Electron Microscopic ◽

Dairy Plant

The antimicrobial effects of two commonly used dairy plant sanitizers on Listeria monocytogenes ATCC 7644 were studied. The two sanitizers used were commercial sodium hypochlorite and quaternary ammonium compound (QAC). The effects were studied on L. monocytogenes in vitro and on stainless steel chips inoculated with the organism. Cells were exposed to concentrations of 0, 50, 100, 200, 400, and 800 ppm chlorine and QAC for 1, 2, and 5 minutes, and neutralized with tryptic soy broth. Decreases in cell numbers ranged from 3-logs to >4-logs in vitro, whereas with the stainless steel, it ranged from 1-log to >4-logs. Scanning electron microscopic (SEM) studies were done to evaluate the attachment characteristics of L. monocytogenes as compared to those of Escherichia coli on stainless steel. L. monocytogenes was found to produce a fibrous-like material similar in appearance to acidic polysaccharide fibrils produced by Pseudomonas sp., which appeared to be removed by the sanitizer solutions.

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Effect of Time, Temperature and Transport Media on the Recovery of Listeria monocytogenes from Environmental Swabs

Journal of Food Protection ◽

10.4315/jfp-20-334 ◽

2020 ◽

Author(s):

Diana Stewart ◽

Yadwinder Singh Rana ◽

Kaiping Deng ◽

Geethaanjali Vijayakumar ◽

Lanlan Yin ◽

...

Keyword(s):

Stainless Steel ◽

Logistic Regression ◽

Listeria Monocytogenes ◽

Sodium Hypochlorite ◽

Food Processing ◽

Storage Time ◽

Cheese Whey ◽

Storage Temperature ◽

Food Matrix ◽

Processing Facility

Environmental monitoring for Listeria monocytogenes in food processing environments is key for ensuring the safety of ready-to-eat foods. For sampling, swabs are often hydrated with a wetting or transport medium which may contain neutralizers and other ingredients. After swabbing the environment, the swabs may then be transported or shipped cold to an off-site laboratory for testing, ideally within 48 h. Extended shipping times may subject the pathogen to increased temperatures in the presence of the wetting medium, organics, and other chemicals from the processing facility which may confound detection. This study evaluated growth and detection of L. monocytogenes on stainless steel exposed to either buffer or sodium hypochlorite prior to drying. Swabs were rehydrated with Butterfield’s Phosphate Buffer, Neutralizing Buffer, Letheen Broth or Dey-Engley Neutralizing Broth prior to swabbing. Swabs were stored in the presence of no added food, cheese whey or ice cream under both optimal (4°) and sub-optimal (15°C) temperatures for up to 72 h. Overall, there was no growth of L. monocytogenes at 4°C through 72 h storage, though enrichment from these swabs was dependent on the presence and type of food matrix. Pathogen growth during storage at 15°C was more variable and depended on both the food matrix and transport media used, with Dey-Engley and Letheen Broth allowing for the highest population increases. Overall, more enrichments resulting in L. monocytogenes detections were observed when using Letheen Broth and Neutralizing Buffer than Dey-Engley which resulted in fewer detections at 15°C. Logistic regression and Cochran-Mantel-Haenszel (CMH) analyses determined that storage temperature, transport media, and food matrix all significantly affected detection of L. monocytogenes , while storage time did not have a clear effect on recovery from swabs.

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Evaluation of the efficacy of commercial sanitizers against adhered and planktonic cells of Listeria monocytogenes and Salmonella spp.

Food Science and Technology ◽

10.1590/s0101-20612012005000084 ◽

2012 ◽

Vol 32 (3) ◽

pp. 606-612 ◽

Cited By ~ 10

Author(s):

Julia Carballo ◽

Ana-Belén Araújo

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Food Industry ◽

Pathogenic Bacteria ◽

Antimicrobial Activities ◽

Planktonic Cells ◽

Salmonella Spp ◽

Planktonic Bacteria ◽

Attached Bacteria ◽

Ammonium Compounds

Antimicrobial activities of two commercial disinfectants, alone or combined with heat, against three Salmonella strains and three Listeria monocytogenes strains were studied. The efficacy of disinfectants against planktonic bacteria and bacteria attached to three food contact industrial surfaces (stainless steel, polytetraflourethylene, and rubber) was investigated. The tests were conducted using the sanitizer (quaternary ammonium compounds, and alquyldiethylenediamineglycine and di-alquyldiamineethylglycine) concentrations recommended by the manufacturers, and concentrations twice and four times higher than those values. The recommended concentrations were not effective to kill bacteria, especially when they were attached to surfaces. Concentrations of disinfectants twice and four times higher than those recommended were needed to fully eliminate planktonic bacteria. These same sanitizer concentrations were not sufficient to remove attached bacteria. To remove them from the surfaces, a treatment with recommended concentrations in combination with heat was needed. Our results indicate that these two pathogenic bacteria could survive common sanitation programs used in the food industry.

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Synergistic effect of a combination of ultraviolet–C irradiation and sodium hypochlorite to reduce Listeria monocytogenes biofilms on stainless steel and eggshell surfaces

Food Control ◽

10.1016/j.foodcont.2016.05.003 ◽

2016 ◽

Vol 70 ◽

pp. 103-109 ◽

Cited By ~ 15

Author(s):

Minhui Kim ◽

Shin Young Park ◽

Sang-Do Ha

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Synergistic Effect ◽

Sodium Hypochlorite ◽

Ultraviolet C

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Effect of Octenidine Hydrochloride on Planktonic Cells and Biofilms of Listeria monocytogenes

Applied and Environmental Microbiology ◽

10.1128/aem.02807-08 ◽

2009 ◽

Vol 75 (12) ◽

pp. 4089-4092 ◽

Cited By ~ 19

Author(s):

Mary Anne Roshni Amalaradjou ◽

Carol E. Norris ◽

Kumar Venkitanarayanan

Keyword(s):

Stainless Steel ◽

Organic Matter ◽

Listeria Monocytogenes ◽

Food Processing ◽

Planktonic Cells ◽

Food Borne ◽

Dry Milk ◽

Presence And Absence ◽

Nonfat Dry Milk

ABSTRACT Listeria monocytogenes is a food-borne pathogen capable of forming biofilms and persisting in food processing environments for extended periods of time, thereby potentially contaminating foods. The efficacy of octenidine hydrochloride (OH) for inactivating planktonic cells and preformed biofilms of L. monocytogenes was investigated at 37, 21, 8, and 4°C in the presence and absence of organic matter (rehydrated nonfat dry milk). OH rapidly killed planktonic cells and biofilms of L. monocytogenes at all four temperatures. Moreover, OH was equally effective in killing L. monocytogenes biofilms on polystyrene and stainless steel matrices in the presence and absence of organic matter. The results underscore OH's ability to prevent establishment of L. monocytogenes biofilms by rapidly killing planktonic cells and to eliminate preformed biofilms, thus suggesting that it could be used as a disinfectant to prevent L. monocytogenes from persisting in food processing environments.

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Destruction of Listeria monocytogenes Biofilms on Stainless Steel Using Monolaurin and Heat1

Journal of Food Protection ◽

10.4315/0362-028x-58.3.251 ◽

1995 ◽

Vol 58 (3) ◽

pp. 251-255 ◽

Cited By ~ 25

Author(s):

DEOG-HWAN OH ◽

DOUGLAS L. MARSHALL

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Food Industry ◽

Adherent Cells ◽

Planktonic Cells ◽

Antimicrobial Effects ◽

Biofilm Removal ◽

Nutrient Environment ◽

Physical Treatments

Individual and combined antimicrobial effects of monolaurin and heat on planktonic, 1-day adherent, or 7-day adherent cells of Listeria monocytogenes were determined to evaluate biofilm removal from stainless steel. Planktonic cells were more sensitive to heat and monolaurin than were cells attached to stainless steel. Young (1-day) biofilm cells were more sensitive to each treatment than were old (7-day) biofilm cells. Adherent cells were destroyed by 50 μg/ml monolaurin combined with heating at 65°C for 5 min. Cells in a rich nutrient environment were more resistant to treatment than were cells in a depleted nutrient environment. Results demonstrate the usefulness of combining chemical and physical treatments to control L. monocytogenes biofilm problems in the food industry.

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Formation of Biofilms by Listeria monocytogenes under Various Growth Conditions

Journal of Food Protection ◽

10.4315/0362-028x-68.1.92 ◽

2005 ◽

Vol 68 (1) ◽

pp. 92-97 ◽

Cited By ~ 98

Author(s):

ANDREW G. MOLTZ ◽

SCOTT E. MARTIN

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Stainless Steel ◽

Listeria Monocytogenes ◽

Cell Density ◽

Polyvinyl Chloride ◽

Growth Medium ◽

Biofilm Formation ◽

Growth Conditions ◽

Scanning Electron

Eight strains of Listeria monocytogenes (7644, 19112, 15313, Scott A, LCDC, 10403S, SLCC, and 1370) produce biofilms when grown on polyvinyl chloride microtiter well plates. The growth medium (tryptic soy broth [TSB] or modified Welshimer's broth [MWB] at 32°C) influenced the amount of biofilm formed; maximum biofilms were formed in MWB by six strains and in TSB by the remaining two strains. This result suggests that the growth medium is critical in development of L. monocytogenes biofilm. This organism also produced biofilms on stainless steel chips. Biofilm formation on these chips was observed following growth in TSB at 4, 20, and 37°C. After 20 h of incubation at 20 or 37°C, the cell density was approximately 106 CFU per chip, and after 4 days incubation at 4°C, the cell density was 105 CFU per chip. L. monocytogenes strain Scott A biofilm formation on stainless steel chips was visualized using scanning electron microscopy, which revealed dense aggregates of cells held together by meshlike webbing.

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Attachment to stainless steel by Mir Space Station bacteria growing under modeled reduced gravity at varying nutrient concentrations

Biofilms ◽

10.1017/s1479050504001437 ◽

2005 ◽

Vol 2 (1) ◽

pp. 1-7 ◽

Cited By ~ 14

Author(s):

P. W. Baker ◽

L. G. Leff

Keyword(s):

Stainless Steel ◽

Biofilm Formation ◽

Normal Gravity ◽

Space Station ◽

Water System ◽

Planktonic Cell ◽

Nutrient Concentrations ◽

Reduced Gravity ◽

Planktonic Cells ◽

Cell Counts

Four bacterial isolates (Chryseobacterium sp., Pseudomonas fluorescens and two Stenotrophomonas maltophilia isolates) originally isolated from the water system aboard the Mir Space Station were grown in two concentrations of nutrient broth under modeled reduced gravity using clinorotation. Sampling was performed over a 7 day period and planktonic cells were enumerated using 4′,6-diamidino-2-phenylindole (DAPI), while those attached to stainless steel were enumerated using the LIVE/DEAD® BacLight™ kit and DAPI. On some of the sampling days for all the isolates, planktonic cell counts were higher under modeled reduced gravity as compared with the normal gravity controls. In contrast, the number of cells of P. fluorescens and one S. maltophilia isolate attached to the stainless steel disks was higher under modeled reduced gravity as compared with normal gravity, whereas no such differences were observed for Chryseobacterium sp. and the other S. maltophilia isolate. Differences in motility among isolates appeared to influence the growth of planktonic cells under modeled reduced gravity but did not appear to be related to biofilm formation.

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Transfer of Persistent Listeria monocytogenes Contamination between Food-Processing Plants Associated with a Dicing Machine

Journal of Food Protection ◽

10.4315/0362-028x-65.7.1129 ◽

2002 ◽

Vol 65 (7) ◽

pp. 1129-1133 ◽

Cited By ~ 109

Author(s):

JANNE M. LUNDÉN ◽

TIINA J. AUTIO ◽

HANNU J. KORKEALA

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Sodium Hypochlorite ◽

Quaternary Ammonium ◽

Quaternary Ammonium Compound ◽

Pfge Type ◽

Ammonium Compound ◽

Type I ◽

Minimal Inhibitory Concentrations ◽

Steel Surfaces

The possibility of the transfer of persistent Listeria monocytogenes contamination from one plant to another with a dicing machine was evaluated, and possible reasons for persistent contamination were analyzed. A dicing machine that diced cooked meat products was transferred from plant A to plant B and then to plant C. After the transfer of the dicing machine, L. monocytogenes PFGE type I, originally found in plant A, was soon also found in plants B and C. This L. monocytogenes PFGE type I caused persistent contamination of the dicing lines in plants B and C. The persistent L. monocytogenes strain and three nonpersistent L. monocytogenes strains found in the dicing line of plant C were tested for adherence to stainless steel surfaces and minimal inhibitory concentrations of a quaternary ammonium compound and sodium hypochlorite, disinfectants widely used in the dicing lines. The persistent strain showed significantly higher adherence to stainless steel surfaces than did the nonpersistent strains. The minimal inhibitory concentrations of sodium hypochlorite were similar for all strains, and the minimal inhibitory concentrations of the quaternary ammonium compound for three of the L. monocytogenes PFGE types, including the persistent PFGE type, were high. All persistent L. monocytogenes PFGE type I isolates were found in an area with high hygienic standards, with the dicing machine being the first point of contamination. These observations show that the dicing machine sustained the contamination and suggest that the dicing machine transferred the persistent L. monocytogenes PFGE type from one plant to another.

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