Biofilm forming abilities of Salmonella are correlated with persistence in fish meal- and feed factories

<p>Abstract</p> <p>Background</p> <p>Feed contaminated with <it>Salmonella </it>spp. constitutes a risk of <it>Salmonella </it>infections in animals, and subsequently in the consumers of animal products. <it>Salmonella </it>are occasionally isolated from the feed factory environment and some clones of <it>Salmonella </it>persist in the factory environment for several years. One hypothesis is that biofilm formation facilitates persistence by protecting bacteria against environmental stress, e.g. disinfection. The aim of this study was to investigate the biofilm forming potential of <it>Salmonella </it>strains from feed- and fishmeal factories. The study included 111 <it>Salmonella </it>strains isolated from Norwegian feed and fish meal factories in the period 1991–2006 of serovar Agona, serovar Montevideo, serovar Senftenberg and serovar Typhimurium.</p> <p>Results</p> <p>Significant differences were found between serovars regarding the abilities to form biofilm on polystyrene (microtiter plate assay) and in the air-liquid interface of nutrient broth (pellicle assay). Strains of serovar Agona and serovar Montevideo were good biofilm producers. In Norwegian factories, clones of these serovars have been observed to persist for several years. Most serovar Senftenberg clones appear to persist for a shorter period, and strains of this serovar were medium biofilm producers in our test systems. Strains of the serovar Typhimurium were relatively poor biofilm producers. <it>Salmonella </it>ser. Typhimurium clones have not been observed to persist even though this serovar is resident in Norwegian wild life. When classifying strains according to persistence or presumed non-persistence, persistent strains produced more biofilm than presumed non-persisting strains.</p> <p>Conclusion</p> <p>The results indicate a correlation between persistence and biofilm formation which suggests that biofilm forming ability may be an important factor for persistence of <it>Salmonella </it>in the factory environment.</p

Survival potential of wild type cellulose deficient Salmonella from the feed industry

<p>Abstract</p> <p>Background</p> <p>Biofilm has been shown to be one way for <it>Salmonella </it>to persist in the feed factory environment. Matrix components, such as fimbriae and cellulose, have been suggested to play an important role in the survival of <it>Salmonella </it>in the environment. Multicellular behaviour by <it>Salmonella </it>is often categorized according to colony morphology into rdar (red, dry and rough) expressing curli fimbriae and cellulose, bdar (brown, dry and rough) expressing curli fimbriae and pdar (pink, dry and rough) expressing cellulose.</p> <p>The aim of the study was to look into the distribution of morphotypes among feed and fish meal factory strains of <it>Salmonella</it>, with emphasis on potential differences between morphotypes with regards to survival in the feed factory environment.</p> <p>Results</p> <p>When screening a total of 148 <it>Salmonella </it>ser. Agona, <it>Salmonella </it>ser. Montevideo, <it>Salmonella </it>ser. Senftenberg and <it>Salmonella </it>ser. Typhimurium strains of feed factory, human clinical and reference collection origin, as many as 99% were able to express rough morphology (rdar or bdar). The dominant morphotype was rdar (74%), however as many as 55% of <it>Salmonella </it>ser. Agona and 19% of <it>Salmonella </it>ser. Senftenberg displayed the bdar morphology.</p> <p>Inconsistency in Calcofluor binding, indicating expression of cellulose, was found among 25% of all the strains tested, however <it>Salmonella </it>ser. Agona showed to be highly consistent in Calcofluor binding (98%).</p> <p>In biofilm, <it>Salmonella </it>ser. Agona strains with bdar mophology was found to be equally tolerant to disinfection treatment as strains with rdar morphotype. However, rdar morphology appeared to be favourable in long term survival in biofilm in a very dry environment.</p> <p>Chemical analysis showed no major differences in polysaccharide content between bdar and rdar strains. Our results indicate that cellulose is not a major component of the <it>Salmonella </it>biofilm matrix.</p> <p>Conclusion</p> <p>The bdar morphotype is common among <it>Salmonella </it>ser. Agona strains isolated from the factory environment. The rdar and the bdar strains were found to be equally tolerant to disinfectants, while the rdar strain was found to be more tolerant to long-term desiccation and nutrient depletion in biofilm than the bdar strain. Cellulose does not appear to be a major component of the <it>Salmonella </it>biofilm matrix.</p

Micro ecosystems from feed industry surfaces: a survival and biofilm study of Salmonella versus host resident flora strains

<p>Abstract</p> <p>Background</p> <p>The presence of <it>Salmonella </it>enterica serovars in feed ingredients, products and processing facilities is a well recognized problem worldwide. In Norwegian feed factories, strict control measures are implemented to avoid establishment and spreading of <it>Salmonella </it>throughout the processing chain. There is limited knowledge on the presence and survival of the resident microflora in feed production plants. Information on interactions between <it>Salmonella </it>and other bacteria in feed production plants and how they affect survival and biofilm formation of <it>Salmonella </it>is also limited. The aim of this study was to identify resident microbiota found in feed production environments, and to compare the survival of resident flora strains and <it>Salmonella </it>to stress factors typically found in feed processing environments. Moreover, the role of dominant resident flora strains in the biofilm development of <it>Salmonella </it>was determined.</p> <p>Results</p> <p>Surface microflora characterization from two feed productions plants, by means of 16 S rDNA sequencing, revealed a wide diversity of bacteria. Survival, disinfection and biofilm formation experiments were conducted on selected dominant resident flora strains and <it>Salmonella</it>. Results showed higher survival properties by resident flora isolates for desiccation, and disinfection compared to <it>Salmonella </it>isolates. Dual-species biofilms favored <it>Salmonella </it>growth compared to <it>Salmonella </it>in mono-species biofilms, with biovolume increases of 2.8-fold and 3.2-fold in the presence of <it>Staphylococcus </it>and <it>Pseudomonas</it>, respectively.</p> <p>Conclusions</p> <p>These results offer an overview of the microflora composition found in feed industry processing environments, their survival under relevant stresses and their potential effect on biofilm formation in the presence of <it>Salmonella</it>. Eliminating the establishment of resident flora isolates in feed industry surfaces is therefore of interest for impeding conditions for <it>Salmonella </it>colonization and growth on feed industry surfaces. In-depth investigations are still needed to determine whether resident flora has a definite role in the persistence of <it>Salmonella </it>in feed processing environments.</p

The Effect of Disinfectants on Quinolone Resistant E. coli (QREC) in Biofilm

The aim of disinfection is to reduce the number of microorganisms on surfaces which is a challenge due to biofilms. In the present study, six quinolone resistant Escherichia coli (QREC) strains with three different biofilm matrix compositions were included to assess the log10 colony forming units (CFU) reduction effect of three disinfectants at various exposure times on biofilm of different ages and morphotypes. Biofilm was formed on stainless steel coupons for two and five days before transferred to tubes with Virocid 0, 25%, VirkonS 1%, and TP990 1% and left for various exposure times. The biofilms were scraped off and serial dilutions were spread on blood agar plates where colony forming units (CFU) were counted. A mean log10 CFU reduction &ge;4 was seen on two-day-old biofilm with VirkonS and Virocid (30 min) but not on five-day old biofilm. TP990 did not display sufficient effect under the conditions tested. The bactericidal effect was inferior to that reported on planktonic bacteria. The findings of this study should be considered when establishing both disinfectant routines and standard susceptibility tests, which further should accommodate E. coli biofilms and not only Pseudomonas as is the case today

The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections

Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment

Bioactive glass S53P4 eradicatesStaphylococcus aureusin biofilm/planktonic statesin vitro

Background:Increasing antimicrobial resistance to antibiotics is a substantial health threat. Bioactive glass S53P4 (BAG) has an antimicrobial effect that can reduce the use of antibiotics. The aim of this study was to evaluate the antimicrobial efficacy of BAGin vitroon staphylococci in biofilm and in planktonic form. Secondary aims were to investigate whether supernatant fluid primed from BAG retains the antibacterial capacity and if ciprofloxacin enhances the effect. Methods:BAG-S53P4 granules, &lt;45 mu m, primed in tryptic soy broth (TSB) were investigated with granules present in TSB (100 mg/mL) and after removal of granules (100, 200, and 400 mg/mL). The efficacy of BAG to eradicateStaphylococcus aureusbiofilmin vitrowas tested using 10 different clinical strains and 1 reference strain in three test systems: the biofilm-oriented antiseptic test based on metabolic activity, the biofilm bactericidal test based on culturing surviving bacteria, and confocal laser scanning microscopy (CLSM) combined with LIVE/DEAD staining. Results:Exposure to 48 h primed BAG granules (100 mg/mL) produced bactericidal effects in 11/11 strains (p = 0.001), and CLSM showed reduction of viable bacteria in biofilm (p = 0.001). Supernatant primed 14 days, 400 mg/mL, reduced metabolic activity (p &lt; 0.001), showed bactericidal effects for 11/11 strains (p = 0.001), and CLSM showed fewer viable bacteria (p = 0.001). The supernatant primed for 48 h, or in concentrations lower than 400 mg/mL at 14 days, did not completely eradicate biofilm. Conclusion:Direct exposure to BAG granules, or primed supernatant fluid, effectively eradicatedS. aureusin biofilm. The anti-biofilm effect is time- and concentration-dependent. When BAG had reached its full antimicrobial effect, ciprofloxacin had no additional effect