Myelin Oligodendrocyte Glycoprotein (MOG) Antibody-Associated CNS Demyelination: Clinical Spectrum and Comparison with Aquaporin-4 Antibody Positive Neuromyelitis Optica Spectrum Disorder.

BACKGROUND: The clinical phenotypes of myelin oligodendrocyte glycoprotein (MOG) antibody disease, its disease course, and treatment are poorly understood and much work needs to be done towards this. OBJECTIVE: To characterize the clinico-radiologic spectrum and treatment outcomes of MOG antibody disease and differentiate it from aquaporin-4 (AQP-4) antibody positive neuromyelitis optica spectrum disorders (NMO-SD). METHODS: A single-center, observational study from Western India during 2017-2019, of 48 patients with either MOG antibody positive (21 patients) or AQP-4 antibody positive (27 patients) central nervous system demyelination. RESULTS: MOG antibody group had median age 32.2 years, no gender bias, median disease duration 40 months, relapses in 9 patients (43%), and median 2.5 (1-16) episodes per patient. Onset phenotypes included isolated bilateral optic neuritis (ON) (43%), isolated unilateral ON (19%), acute brainstem syndrome (19%), simultaneous ON with myelitis (9%), isolated myelitis (5%), and acute disseminated encephalomyelitis optic neuritis (ADEM-ON) (5%). Characteristic neuroimaging abnormalities were anterior segment longitudinally extensive ON, upper brainstem, and thoracic cord involvement (both short and long segment lesions). Most patients (86%) responded well to steroids, only 3/21 required rescue immunotherapy. In total, 6 out of 46 eyes affected developed permanent visual disability, while one patient had motor disability. The features differentiating MOG from AQP-4 antibody group were: no female predilection, preferential optic nerve involvement, characteristic neuroimaging abnormalities, and favorable therapeutic response and outcome. CONCLUSIONS: MOG disease commonly presents as severe ON, myelitis, acute brainstem syndrome, ADEM or their combinations. Early identification, treatment, and maintenance immunosuppression are necessary. It can easily be differentiated from NMO-SD using clinico-radiological features and therapeutic response.

Induction and stability of oxidative stress adaptation in Listeria monocytogenes EGD (Bug600) and F1057 in sublethal concentrations of H2O2 and NaOH.

Food processing and food handling environments may contain residual levels of sanitizers or cleaners which may trigger oxidative stress adaptation in Listeria monocytogenes. The aim of this study was to determine the induction and stability of oxidative stress adaptation in L. monocytogenes EGD (Bug600) (serotype 1/2a) and F1057 (serotype 4b) at different concentrations and times of sublethal oxidative stress induced by H2O2 or sublethal alkali stress induced by NaOH at 37°C. Both L. monocytogenes Bug600 and F1057 strains showed significantly higher survival in lethal oxidative stress (1000ppm H2O2) after pre-exposure to 50ppm H2O2 for 30min compared to control cells (no pre-exposure to H2O2). When the cells were pre-exposed to sublethal alkali stress by NaOH, the oxidative stress adaptation was induced within 5min in L. monocytogenes. The survival of both L. monocytogenes strains was increased by 2 to 4.5 logs in lethal oxidative stress when the cells were pre-exposed to sublethal alkali stress at pH9 from 5 to 120min by NaOH compared to control cells (no pre-exposure to sublethal alkali pH). Two other alkali reagents tested (KOH and NH4OH) also induced oxidative stress adaptation in L. monocytogenes. For both L. monocytogenes strains, the oxidative stress adaptation induced by sublethal H2O2 was reversible in 30min and that induced by sublethal alkali stress was reversible within 60min at 37°C in the absence of such sublethal stress. These findings show that sublethal oxidative or alkali stress conditions can induce oxidative stress adaptation that may increase the risk of survival of L. monocytogenes cells in lethal oxidative stress.

Stability of sublethal acid stress adaptation and induced cross protection against lauric arginate in Listeria monocytogenes.

The stability of acid stress adaptation in Listeria monocytogenes and its induced cross protection effect against GRAS (generally recognized as safe) antimicrobial compounds has never been investigated before. In the present study, the acid stress adaptation in L. monocytogenes was initially induced in pH 5.0 tryptic soy broth supplemented with 0.6% yeast extract (TSB-YE) at 37 °C. Subsequently, the stability of acid stress adaptation, which was defined as the capacity to maintain its acquired acid adaptation after induction in the absence of sublethal acid stress, was determined at 37 °C, 22 °C or 4 °C in broth and in different food substrates. Then, the acid stress adaptation induced cross protection against lauric arginate (LAE) and its stability was investigated in TSB-YE, milk and carrot juice. Our findings show that the acid stress adaptation was stable at 4 °C up to 24h but was reversed at 37 °C or 22 °C within 2h. In the cross protection assay with LAE, the acid stress adapted cells had approximately 2 log CFU/ml greater survival than non-adapted cells in broth at 22 °C or in milk and carrot juice at 4 °C. The acid adaptation induced cross protection against LAE in L. monocytogenes was reversible within 1h at 4 °C in the absence of sublethal acid stress. Our findings suggest that the stability of acid adaptation in L. monocytogenes under cold conditions should be taken into account when the risk analysis is performed during food processing.

Evaluation of antigout activity of Phyllanthus emblica fruit extracts on potassium oxonate-induced gout rat model.

AIM: The present study has been conducted to evaluate antigout activity of aqueous and alcoholic extracts of Phyllanthus emblica fruits following its 28 days repeated oral administration on potassium oxonate-induced gout rat model. MATERIALS AND METHODS: The study was conducted on 42 male Sprague-Dawely rats dividing them in seven groups having six rats in each group. Groups I, II, and III served as vehicle control group, gout control group, and standard treatment control group, respectively. Rats of all the groups except vehicle control group were administered potassium oxonate at 250 mg/kg (IP), throughout the study period (28 days) for induction of gout. Groups IV and V received aqueous extract of P. emblica at 200 and 400 mg/kg, and Groups VI and VII received alcoholic extract of P. emblica at 200 and 400 mg/kg (daily oral for 28 days). At the end of study, all the rats were subjected to blood collection; blood and serum sample were analyzed for hematological and biochemical parameters, respectively. After collection of blood samples on the 29(th) day, all the rats were sacrificed and subjected to post mortem examination to determine the presence or absence of gross and histopathological lesions in kidney tissues. RESULTS: At the end of study, rats of gout control group showed increase in platelets counts, serum creatinine, uric acid, blood urea nitrogen (BUN), and xanthine oxidase (XO) enzyme level along with alterations in kidney tissues as compared to vehicle control group. Gouty rats treated with aqueous and alcoholic extracts of P. emblica at 200 and 400 mg/kg body weight and standard treatment allopurinol at 5 mg/kg body weight showed reduction in platelets counts, serum creatinine, uric acid, BUN, and XO enzyme level along with significant improvements in histological structure of kidney as compared to rats of gout control group. CONCLUSION: Oral administration of aqueous and alcoholic extracts of P. emblica fruits for 28 days has shown protection against gout in dose-dependent manner in rats.

Once myasthenic, always myasthenic? observations on the behavior and prognosis of myasthenia gravis in a cohort of 100 patients.

BACKGROUND: The natural history of myasthenia gravis [MG] is unpredictable: In the first few years the disease course is worst with subsequent gradual disease stabilization. However, some patients tend to have continued disease activity or resurgence of the disease many years into the illness. The factors correlating with disease course need further evaluation. AIMS: To study the patterns of remissions, worsening and exacerbations in patients with MG and correlate various factors affecting them. SETTINGS AND DESIGN: Retrospective, Institute Review Board (IRB) approved study in tertiary referral neurology center. MATERIALS AND METHODS: Hundred patients with acquired MG confirming the inclusion criteria were studied. Pharmacological remissions, complete stable remissions, exacerbations, worsening episodes were analyzed with respect to age of onset, disease extent, disease severity at onset and worst of illness, acetyl choline receptor antibody positivity, thymectomy status, period of disease, pharmacotherapy and crisis episodes. RESULTS AND CONCLUSIONS: In this cohort the percentage of new remission rates per year steadily declined after the first year. Ocular myasthenia had lesser clinical worsening episodes and high chance of complete stable remission. Generalized disease had less chance drug free remission. The risk of episodes of worsening persisted at a steady rate over a period of time, being maximum in the first year. The risk of exacerbations was unpredictable and could occur after prolonged clinical quiescence, often was related to reduction of immunosuppression. The disease course did not differ significantly in the juvenile and adult age-groups. There was a strong case for permanent immunomodulation in MG.

Low, medium, and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat.

A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with an initial cell density of 10(7) CFU/ml were analyzed for their heat tolerance at 60°C for 10 min. These L. monocytogenes strains were categorized into three heat tolerance groups: low (<2 log CFU/ml survival), medium (2 to 4 log CFU/ml survival), and high (4 to 6 log CFU/ml survival). Serotype 1/2a strains had relatively low heat tolerance; seven of the eight tested strains were classified as low heat tolerant. Of the two serotype 1/2b strains tested, one was very heat sensitive (not detectable) and the other was very heat resistant (5.4 log CFU/ml survival). Among the 16 serotype 4b strains, survival ranged from not detectable to 4 log CFU/ml. When one L. monocytogenes strain from each heat tolerance group was subjected to sublethal heat stress at 48°C for 30 or 60 min, the survival of heat-stressed cells at 60°C for 10 min increased by 5 log CFU/ml (D60°C-values nearly doubled) compared with the nonstressed control cells. Sublethal heat stress at 48°C for 60 or 90 min increased the lag phase of L. monocytogenes in tryptic soy broth supplemented with 0.6% yeast extract at room temperature by 3 to 5 h compared with nonstressed control cells. The heat stress adaptation in L. monocytogenes was reversed after 2 h at room temperature but was maintained for up to 24 h at 4°C. Our results indicate a high diversity in heat tolerance among strains of L. monocytogenes, and once acquired this heat stress adaptation persists after cooling, which should be taken into account while conducting risk analyses for this pathogen.

Influence of temperature on acid-stress adaptation in Listeria monocytogenes.

Our findings show that temperature plays a significant role in the induction of acid-stress adaptation in Listeria monocytogenes, and two distinct patterns were observed: (1) Presence of sublethal acid at 37°C or 22°C significantly induced acid-stress adaptation; and (2) Presence of sublethal acid at 4°C did not induce any acid-stress adaptation. Both patterns were confirmed by two experimental models: (1) L. monocytogenes cells were first grown at 37°C and then exposed to sublethal acid at 37°C, 22°C, and 4°C prior to lethal acid challenge; (2) Alternatively, L. monocytogenes cells were first grown at 4°C for 20 days before pre-exposure to sublethal acid and then challenged with lethal acid. Regardless of whether L. monocytogenes cells were simultaneously exposed with both cold stress and sublethal acid stress, or subjected to cold growth first before exposure to sublethal acid, no acid-stress adaptation was induced at 4°C. We also found that acid-stress adaptation in L. monocytogenes did not occur in acidic whey at 4°C. Bead beating treatment prior to mild acid pre-exposure at 4°C partially induced acid adaptation in L. monocytogenes. Our findings suggest that cold temperature can prevent the risk of acid-stress adaptation in L. monocytogenes.

Anti cancerous efficacy of Ayurvedic milk extract of Semecarpus anacardium nuts on hepatocellular carcinoma in Wistar rats.

The objective of the study was to determine the anticancerous efficacy of Ayurvedic preparation made of Semecarpus anacardium (SA) nuts. Five groups of rats were used for the study. Group I served as water control. Hepatocellular carcinoma (HCC) was induced in groups II, III and IV animals using N-nitrosodiethylamine as inducing agent followed by phenobarbitone as promoter for 13 weeks. Group-II animals were kept untreated as hepatocellular carcinoma control. Group-III animals were treated with Ayurvedic milk extract of Semecarpus anacardium nuts at dose mentioned in Ashtangahridaya, an authentic book of Ayurveda for 49 days and group-IV animals were treated with doxorubicin as reference drug at dose of 1mg/kg twice a week for 7 weeks. Group V animals were kept as drug (SA nut milk extract) control for studying the effect of nut milk extract on normal rats. After 154 days of experiment, all animals were subjected to screening for HCC by estimation of liver enzymes, HCC marker (alpha-2 macroglobulin) and histopathology. Both liver enzymes and HCC marker were increased in hepatocellular carcinoma control along with neoplastic changes in liver and were decreased in Semecarpus anacardium nut milk extract treated group. The Ayurvedic drug showed positive correlation with the action of doxorubicin. This study demonstrated the efficacy of Semecarpus anacardium nut milk extract for the treatment of hepatocellular carcinoma either alone or along with chemotherapy.

Are syncopes in sitting and supine positions different? Body positions and syncope: a study of 111 patients.

CONTEXT: Syncope is a common cause of transient loss of consciousness. In the analysis of patients having syncope, body position has not been systematically studied and correlated with triggers, prodromal symptoms and circumstances. This correlation is important in differentiating syncope from its mimics. AIMS: To study syncope with respect to body positions, triggers, prodromal symptoms and circumstances. SETTINGS AND DESIGN: Prospective study set in Neurology Department of Tertiary Care Center. MATERIALS AND METHODS: Patients fulfilling guidelines set by The Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC) were recruited. Detailed clinical history, examination and investigations (ECG, 2D-ECHO, Head Up Tilt Test, Holter monitor, EEG, MRI Brain) were carried out. RESULTS: Out of the 111 recruited patients, 67 developed syncope in standing, 16 in sitting, 23 in both standing and sitting, 1 in both sitting and supine and 4 in all three positions. Prodromal symptoms were present in 81% while triggers in 42% and circumstances in 41% of patients. Black out, sweating, dizziness and headache were most common prodromal symptoms. Intense pain, smell and fear were most common triggers while prolonged standing, hot crowded room and fasting were most common circumstances associated with syncope. CONCLUSIONS: Against common belief, syncope can occur in sitting as well as in supine position. Emotional triggers were commoner in patients with syncope in supine and sitting positions while prodromal symptoms and circumstances were similar for all positions. Syncope should be considered in body positions other than standing.

Synergistic activity between lauric arginate and carvacrol in reducing Salmonella in ground turkey.

In the present study, low concentrations of carvacrol (0.025 to 0.2%) and lauric arginate (LAE; 25 to 200 ppm) were tested at 4, 22, and 45°C in a broth model, and higher concentrations of carvacrol (0.1 to 5%) and LAE (200 to 5,000 ppm) were tested individually and in combination at 4°C in 3 different ground turkey samples (with 15, 7, and 1% fat content) for their effectiveness against a 3-strain mixture of Salmonella. A low concentration of 25 ppm of LAE or 0.025% carvacrol had no effect on Salmonella in a broth model, but their mixture showed a synergistic action by reducing 6 log cfu/mL Salmonella counts to a nondetectable level within 30 min of exposure. The US Food and Drug Administration-recommended 200 ppm of LAE was not sufficient for Salmonella reductions in ground turkey when applied internally. High concentrations of 2,000 to 5,000 ppm of LAE or 1 to 2% carvacrol were needed to reduce Salmonella counts by 2 to 5 log cfu/g in ground turkey by internal application. No specific relationship existed between fat content and LAE or carvacrol concentrations for Salmonella reductions. For example, 2,000 ppm of LAE could reduce Salmonella counts by 4 log cfu/g in 1% fat-containing turkey samples but very similar ~1.5 log cfu/g reductions in both 7 and 15% fat-containing ground turkey samples. For the total microbial load, about 2,000 ppm of LAE or 2% of carvacrol treatments were needed to achieve 2 to 3 log (P ≤ 0.05) cfu/g reductions in different turkey samples. A mixture of 1% carvacrol and 2,000 ppm of LAE exhibited a synergistic action in ground turkey containing 7% fat by reducing the Salmonella counts by 4 log cfu/g, which was not found with individual antimicrobial treatments.

Inhibition and inactivation of Salmonella typhimurium biofilms from polystyrene and stainless steel surfaces by essential oils and phenolic constituent carvacrol.

Persistence of Salmonella biofilms within food processing environments is an important source of Salmonella contamination in the food chain. In this study, essential oils of thyme and oregano and their antimicrobial phenolic constituent carvacrol were evaluated for their ability to inhibit biofilm formation and inactivate preformed Salmonella biofilms. A crystal violet staining assay and CFU measurements were utilized to quantify biofilm cell mass, with evaluating factors such as strain variation, essential oil type, their concentrations, exposure time, as well as biofilm formation surface. Of the three Salmonella strains, Salmonella Typhimurium ATCC 23564 and Salmonella Typhimurium ATCC 19585 produced stronger biofilms than Salmonella Typhimurium ATCC 14028. Biofilm formation by different Salmonella strains was 1.5- to 2-fold higher at 22°C than at 30 or 37°C. The presence of nonbiocidal concentrations of thyme oil, oregano oil, and phenolic carvacrol at 0.006 to 0.012% suppressed Salmonella spp. biofilm formation 2- to 4-fold, but could not completely eliminate biofilm formation. There was high correlation in terms of biofilm inactivation, as determined by the crystal violet-stained optical density (at a 562-nm wavelength) readings and the viable CFU counts. Reduction of biofilm cell mass was dependent on antimicrobial concentration. A minimum concentration of 0.05 to 0.1% of these antimicrobial agents was needed to reduce a 7-log CFU biofilm mass to a nondetectable level on both polystyrene and stainless steel surfaces within 1 h of exposure time.

Reduction of Listeria monocytogenes biofilms on stainless steel and polystyrene surfaces by essential oils.

Plant-derived essential oils were tested for their ability to eliminate biofilms of Listeria monocytogenes on polystyrene and stainless steel surfaces. Various concentrations of essential oils were tested with different contact times on biofilms of various ages. Preliminarily screening of nine essential oils and related phenolic compounds in a disk diffusion assay revealed that thyme oil, oregano oil, and carvacrol had the highest antimicrobial activity. Further screening of these three compounds against 21 L. monocytogenes strains representing all 13 serotypes indicated some strain-specific variations in antimicrobial activity. For 1-day-old biofilms of mixed L. monocytogenes strains produced at 22°C on polystyrene microtiter plates, only 0.1% concentrations of thyme oil, oregano oil, and carvacrol were needed to eliminate 7 log CFU per well. On the stainless steel coupons, a 0.5% concentration of these compounds was adequate to completely eliminate 4-day-old biofilms at 7 log CFU per coupon. Our findings indicate that these compounds are potential candidates for elimination of L. monocytogenes biofilms on stainless steel and polystyrene surfaces.

Reduction of Listeria monocytogenes in raw catfish fillets by essential oils and phenolic constituent carvacrol.

The antimicrobial activity of various essential oils and carvacrol was determined on fresh raw catfish fillets against a 4-strain Listeria monocytogenes mixture representing serotypes 1/2b, 3b, 4b, and 4c that were predominantly isolated from catfish processing environments. Thyme oil, oregano oil and carvacrol exhibited concentration and time dependent responses in broth against L. monocytogenes; for example 0.5% concentrations resulted in 4 log CFU/mL reduction within 30 min whereas 0.1% concentrations required more than 24 h for the same level of reduction. Lemon, orange, and tangerine oils, at 0.5% showed listeriostatic effect in which 4 log CFU/mL of the initial L. monocytogenes load was unchanged at 4 °C in 10 d whereas 1% concentrations were listericidal in a time dependent manner. Apart from carvacrol, efficacy of tested essential oils in reducing L. monocytogenes and total microbial load from catfish fillet was very limited. Dipping treatment of catfish fillets in 2% carvacrol solution for 30 min at 4 °C reduced L. monocytogenes to an undetectable level from their initial load of 5 log CFU/g and reduced total microbial load from catfish fillets by approximately 5 log CFU/g. In sensory analysis trained panelist preferred control samples over 2% carvacrol treated samples implying potential limitation in applicability of carvacrol for fillet treatments.

Reduction of Listeria monocytogenes in queso fresco cheese by a combination of listericidal and listeriostatic GRAS antimicrobials.

Single and combined effects of three GRAS (generally recognized as safe) antimicrobials including, bacteriophage P100 (phage P100), lauric arginate (LAE), and potassium lactate-sodium diacetate mixture (PL-SD) were evaluated against Listeria monocytogenes cold growth in queso fresco cheese (QFC). The fate of phage P100 when exposed to LAE (200 ppm) or PL-SD (2.8% PL and 0.2% SD) was determined at 4°C and 30°C in a broth model. Phage P100 was found to be stable in the presence of these antimicrobial agents as plaque forming units (PFU) did not vary between control, LAE or PL-SD treatments. When 9 log CFU/ml of stationary phase cells of L. monocytogenes was exposed to these antimicrobials in tryptic soy broth, there was a 3 to 5 log CFU/ml reduction with phage P100 and a complete 9 log CFU/ml reduction with LAE but no measurable reduction with PL-SD after 24h at 4°C or 30°C. In QFC, the L. monocytogenes populations increased from the initial 3.5 log CFU/cm(2) to 7.7 log CFU/cm(2) in 28 days at 4°C. Treatment with 7.8 log PFU/cm(2) of phage P100 or 200 ppm of LAE showed strong listericidal effect initially by reducing L. monocytogenes counts by 2 to 3.5-4 log CFU/cm(2) while there was a subsequent regrowth of L. monocytogenes at 4°C. Treatment with PL-SD showed strong listeriostatic effect without decreasing L. monocytogenes counts but growth was prevented for 28 days at 4°C. Only the combined treatment of listericidal phage P100 or LAE with listeriostatic PL-SD reduced the initial L. monocytogenes counts by 2-4 log CFU/cm(2) and also kept the L. monocytogenes counts at that reduced level in QFC for 28 days at 4°C.

Effect of moxifloxacin administration on pharmacokinetics of tolfenamic acid in rats

Pharmacokinetics of tolfenamic acid as a single drug (4 mg/kg, intramuscularly) and its co-administration with moxifloxacin (5 mg/kg, intramuscularly) in wistar rats were studied. The plasma drug concentration of tolfenamic acid was assayed by LC-MS/MS. Following intramuscular administration of tolfenamic acid as single drug and in combination with moxifloxacin in male rats, the mean values of observed peak plasma drug concentration (Cmax), area under plasma drug concentration-time curve (AUC(0-¥) ), volume of distribution (Vz), half-life (t½) and clearance (Cl) were 4111.44 ± 493.15 and 3837.69 ± 351.83 ng/ml, 20280.77 ± 3501.67 and 15229.18 ± 678.80 ng.h/ml, 822.17 ± 115.38 and 1249.64 ± 139.52 ml, 2.59 ± 0.16 and 3.27 ± 0.32 hr, and 218.39 ± 25.47 and 265.18 ± 11.36 ml/hr, respectively. The peak plasma drug concentration (Cmax) was significantly higher in female rats compared to male rats. The volume of distribution (Vz) of the drug was significantly higher (P < 0.05) in moxifloxacin-treated male rats compared to female rats. Concomitant administration of moxifloxacin may alter the disposition of tolfenamic acid in male rats.

The contribution of transcriptomic and proteomic analysis in elucidating stress adaptation responses of Listeria monocytogenes.

The foodborne transmission of Listeria monocytogenes requires physiological adaptation to various conditions, including the cold, osmotic, heat, acid, alkaline, and oxidative stresses, associated with food hygiene, processing, and preservation measures. We review the current knowledge on the molecular stress adaptation responses in L. monocytogenes cells as revealed through transcriptome, proteome, genetic, and physiological analysis. The adaptation of L. monocytogenes to stress exposure is achieved through global expression changes in a large number of cellular components. In addition, the cross-protection of L. monocytogenes exposed to different stress environments might be conferred through various cellular machineries that seem to be commonly activated by the different stresses. To assist in designing L. monocytogenes mitigation strategies for ready-to-eat food products, further experiments are warranted to specifically evaluate the effects of food composition, additives, preservatives, and processing technologies on the modulation of L. monocytogenes cellular components in response to specific stresses.

Removal of Listeria monocytogenes biofilms with bacteriophage P100.

Listeria monocytogenes is an important foodborne pathogen with a persistent ability to form biofilm matrices in the food processing environments. In this study, we have determined the ability of bacteriophage P100 to reduce L. monocytogenes cell populations under biofilm conditions by using 21 L. monocytogenes strains representing 13 different serotypes. There were considerable differences in the ability of various strains of L. monocytogenes to form biofilms, with strains of serotype 1/2a showing maximum biofilm formation. Irrespective of the serotype, growth conditions, or biofilm levels, the phage P100 treatment significantly reduced L. monocytogenes cell populations under biofilm conditions. On the stainless steel coupon surface, there was a 3.5- to 5.4-log/cm2 reduction in L. monocytogenes cells by phage treatment. These findings illustrate that phage P100 is active against a wide range of L. monocytogenes strains in biofilm conditions.

Bacteriophage significantly reduces Listeria monocytogenes on raw salmon fillet tissue.

We have demonstrated the antilisterial activity of generally recognized as safe (GRAS) bacteriophage LISTEX P100 (phage P100) on the surface of raw salmon fillet tissue against Listeria monocytogenes serotypes 1/2a and 4b. In a broth model system, phage P100 completely inhibited L. monocytogenes growth at 4 degrees Celsius for 12 days, at 10 degrees Celsius for 8 days, and at 30 degrees Celsius for 4 days, at all three phage concentrations of 10(4), 10(6), and 10(8) PFU/ml. On raw salmon fillet tissue, a higher phage concentration of 10(8) PFU/g was required to yield 1.8-, 2.5-, and 3.5-log CFU/g reductions of L. monocytogenes from its initial loads of 2, 3, and 4.5 log CFU/g at 4 or 22 degrees Celsius. Over the 10 days of storage at 4 degrees Celsius, L. monocytogenes growth was inhibited by phage P100 on the raw salmon fillet tissue to as low as 0.3 log CFU/g versus normal growth of 2.6 log CFU/g in the absence of phage. Phage P100 remained stable on the raw salmon fillet tissue over a 10-day storage period, with only a marginal loss of 0.6 log PFU/g from an initial phage treatment of 8 log PFU/g. These findings illustrate that the GRAS bacteriophage LISTEX P100 is listericidal on raw salmon fillets and is useful in quantitatively reducing L. monocytogenes.

Reduction of Listeria monocytogenes on the surface of fresh channel catfish fillets by bacteriophage Listex P100.

Bacteriophage Listex P100 (phage P100) was approved by the U.S. Food and Drug Administration and U.S. Department of Agriculture's Food Safety and Inspection Service for Listeria monocytogenes control on both raw and ready-to-eat food products. In this article, we present the proof of concept on the influence of phage dose, phage contact time, and storage temperature on the listericidal activity of phage P100 in reducing the L. monocytogenes loads on the surface of fresh channel catfish fillet. The fresh catfish fillet samples were surface inoculated with approximately 4.3 log(10) colony forming units (CFU)/g of a two serotype mix (1/2a and 4b) of L. monocytogenes cells and then surface treated with phage P100. L. monocytogenes reduction was influenced by phage contact time and phage dose regardless of higher or lower temperature regimes tested on catfish fillet. The reduction in L. monocytogenes loads (p < 0.05) with the phage P100 dose of 2 x 10(7) plaque forming units (PFU)/g (7.3 log(10) PFU/g) was 1.4-2.0 log(10) CFU/g at 4 degrees C, 1.7-2.1 log(10) CFU/g at 10 degrees C, and 1.6-2.3 log(10) CFU/g at room temperature (22 degrees C) on raw catfish fillet. The phage contact time of 30 min was adequate to yield greater than 1 log(10) CFU/g reduction in L. monocytogenes, whereas 15 min contact time with phage yielded less than 1 log(10) CFU/g reduction in L. monocytogenes loads on catfish fillet. Phage P100 titer was stable on catfish fillet samples, and overall reductions in L. monocytogenes counts were still maintained over a 10-day shelf life at 4 degrees C or 10 degrees C by phage P100 treatment. These findings illustrate the effectiveness of an alternative generally recognized as safe antimicrobial such as bacteriophage Listex P100 in quantitatively reducing L. monocytogenes from fresh catfish fillet surfaces.