scholarly journals Requirement of lmo1930, a Gene in the Menaquinone Biosynthesis Operon, for Esculin Hydrolysis and Lithium Chloride Tolerance in Listeria monocytogenes

2019 ◽  
Vol 7 (11) ◽  
pp. 539 ◽  
Author(s):  
Cameron Parsons ◽  
Midya Jahanafroozi ◽  
Sophia Kathariou
Keyword(s):  
Listeria Monocytogenes ◽  
Lithium Chloride ◽  
Foodborne Pathogen ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Selective Enrichment ◽  
Plant Matter ◽  
Regular Sampling ◽  
Esculin Hydrolysis ◽  
Ferric Ammonium

Listeria monocytogenes is a foodborne pathogen that is widely distributed in nature, having been isolated from a variety of sources such as soil, water, plant matter, and animals. In addition, L. monocytogenes is often detected in the regular sampling of food and food processing environments. The most common method for detecting L. monocytogenes is the use of selective enrichments. Both lithium chloride and esculin, in combination with ferric ammonium citrate, are utilized in several of the most commonly-employed selective enrichment schemes for L. monocytogenes. Here we report that transposon-based inactivation of lmo1930, one of the genes in the menaquinone biosynthesis operon, via transposon mutagenesis severely impaired the ability of L. monocytogenes to grow in the presence of lithium chloride or hydrolyze esculin, and conferred reduced growth and colony size. All phenotypes were restored upon genetic complementation. Thus, strains of L. monocytogenes with mutations leading to inactivation of lmo1930 may evade many commonly-used selective enrichment protocols employed in the detection of L. monocytogenes.

Influence of Bovine Lactoferrin on the Growth of Listeria monocytogenes

1990 ◽  
Vol 53 (6) ◽  
pp. 468-472 ◽  
Author(s):  
K. D. PAYNE ◽  
P. M. DAVIDSON ◽  
S. P. OLIVER ◽  
G. L. CHRISTEN
Keyword(s):  
Listeria Monocytogenes ◽  
Binding Sites ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Bovine Lactoferrin ◽  
Bacteriostatic Effect ◽  
Minimal Growth ◽  
Iron Saturation ◽  
Inhibition Of Growth ◽  
Ferric Ammonium

The influence of bovine lactoferrin (LF) and Apo-LF on growth of Listeria monocytogenes in Ultra-High Temperature (UHT) 2% fat milk was determined. The effect of LF was dependent upon both the degree of iron saturation and concentration. Before iron removal, LF was found to be approximately 52% saturated with iron; and at 23 and 46 mg/ml LF, minimal growth inhibition of L. monocytogenes was observed. Following dialysis, Apo-LF iron saturation was reduced to approximately 18%. At 15 and 30 mg/ml Apo-LF, a bacteriostatic effect against L. monocytogenes was observed. Inhibition of growth associated with Apo-LF was abolished when ferric ammonium citrate was added to saturate the iron binding sites of the Apo-LF.

scholarly journals The Effect of Preenrichment and Selective Enrichment Media on Recovery of Salmonella Typhi from the Tropical Fruit Mamey

2008 ◽  
Vol 91 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Thomas S Hammack ◽  
Andrew P Jacobson ◽  
Wallace H Andrews
Keyword(s):  
Relative Effectiveness ◽  
Culture Method ◽  
Salmonella Typhi ◽  
Positive Test ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Test Portion ◽  
Tropical Fruit ◽  
Selective Enrichment ◽  
Ferric Ammonium

Abstract The Bacteriological Analytical Manual (BAM) Salmonella culture method did not detect Salmonella Typhi in mamey, the tropical fruit that was implicated in a 1999 typhoid outbreak. The relative effectiveness of BAM's nonselective preenrichment and selective media for the recovery of S. Typhi from mamey was examined to determine if the BAM's preenrichment/selective enrichment strategy was the cause of the method's failure with this food. The preenrichment media were lactose broth, buffered peptone water (BPW), and universal preenrichment (UP) broth. The selective enrichment media were selenite cystine (SC) broth, tetrathionate (TT) broth, and Rappaport-Vassiliadis (RV) medium. UP broth was significantly more effective (P < 0.05) than either lactose broth or BPW for the recovery of 2 different S. Typhi strains from mamey. Of 120 test portions tested, 105 S. Typhi-positive test portions were recovered using UP broth, whereas only 1 S. Typhi-positive test portion was recovered using BPW, and no S. Typhi-positive test portions were recovered using lactose broth. SC and TT broths were both significantly more effective (P < 0.05) than RV medium. Of 105 S. Typhi-positive test portions, SC broth recovered 80, TT broth recovered 67, and RV medium recovered 9. After the above comparison, an incomplete UP (UPI) broth formulation was found to be significantly more effective (P < 0.05) than the complete formulation (UPC). Of 80 total positive test portions, UPI recovered 71, whereas UPC recovered only 48. The following UP broth formulations were compared to determine if any of the components of the UP broth formulation were inhibitory to S. Typhi: UPC, UP broth without sodium pyruvate (UPS), UP broth without ferric ammonium citrate (UPF), UP broth without MgSO4 (UPM), and UPI. It was found that none of the ingredients were inhibitory to S. Typhi and that, out of 140 total test portions, UPI and UPF, with 108 and 103 positive test portions, respectively, were significantly more effective (P < 0.05) than the other UP broth formulations (82 for UPC, 74 for UPS, and 60 for UPM). Rather than being inhibitory to the growth of S. Typhi, it appears that ferric ammonium citrate enhanced the growth of competitors which suppressed the growth of S. Typhi. These results demonstrate that UPI and UPF are effective for the recovery of S. Typhi from mamey.

Rapid Detection of Listeria spp. in Food and Environmental Samples by Esculin Hydrolysis

1988 ◽  
Vol 51 (10) ◽  
pp. 762-765 ◽  
Author(s):  
JUDY A. FRASER ◽  
WILLIAM H. SPERBER
Keyword(s):  
Environmental Samples ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Regulatory Agencies ◽  
Wide Range ◽  
Secondary Enrichment ◽  
Esculin Hydrolysis ◽  
Ferric Ammonium ◽  
Time Savings ◽  
The Government

The use of Fraser Broth enables the presumptive detection of Listeria spp. within 48 h, thereby producing major cost and time savings when compared to existing methods. Fraser Broth was developed by modification of the USDA secondary enrichment broth through the addition of lithium chloride and ferric ammonium citrate. Esculin hydrolysis in Fraser Broth results in the production of a black precipitate. Since all Listeria spp. hydrolyse esculin, cultures which do not blacken can be considered to be Listeria-free. The efficacy of Fraser Broth was documented by testing a wide range of food and environmental samples from food processing facilities in parallel with the methods used by the government regulatory agencies. Fraser Broth inoculated from the USDA primary enrichment was found to be more sensitive than either Fraser Broth inoculated from the FDA enrichment or the existing FDA method in the analysis of ice cream products.

scholarly journals New medium for selection and presumptive identification of the Bacteroides fragilis group

1978 ◽  
Vol 7 (5) ◽  
pp. 448-453
Author(s):  
S J Livingston ◽  
S D Kominos ◽  
R B Yee
Keyword(s):  
Clinical Laboratory ◽  
Bacteroides Fragilis ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Characteristic Morphology ◽  
Presumptive Identification ◽  
Laboratory Trial ◽  
Esculin Hydrolysis ◽  
Bacteroides Fragilis Group ◽  
Ferric Ammonium

A medium, Bacteroides fragilis bile-esculin (BBE) agar, was designed for the selection and, presumptive identification of the B. fragilis group. BBE agar contains bile, esculin, ferric ammonium citrate, hemin, and gentamicin in a Trypticase soy agar base. Growth in the presence of 20% bile and esculin hydrolysis, detected by blackening of the medium, provide presumptive evidence for the identification of the B. fragilis group. In addition to stimulating the growth of many strains of the B. fragilis group, hemin provides the option of testing isolates for catalase production. Gentamicin and bile prevent the growth of most organisms other than the esculin-positive bacteroides that can tolerate bile. Of 160 clinical isolates of the B. fragilis group tested on BBE agar, 159 grew well on the medium and 157 blackened it. Other anaerobes, Enterobacteriaceae, and enterococci either failed to grow on BBE agar or did not produce the characteristic morphology and blackening associated with isolates of the B. fragilis group. In a clinical laboratory trial, 687 specimens from patients were inoculated onto BBE agar plates. The B. fragilis group was recovered from 81 (11.8%) of these specimens in 24 to 48 h. Use of BBE agar in the clinical laboratory enables earlier recovery and identification of this important pathogen.

Development of a Simple Recovery-Enrichment System for Enhanced Detection of Heat-Injured Listeria monocytogenes in Pasteurized Milk

2000 ◽  
Vol 63 (4) ◽  
pp. 462-472 ◽  
Author(s):  
ALEX YEOW-LIM TEO ◽  
STEPHEN J. KNABEL
Keyword(s):  
Listeria Monocytogenes ◽  
Magnesium Sulfate ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
State University ◽  
Pasteurized Milk ◽  
Whole Milk ◽  
Penn State ◽  
Ferric Ammonium ◽  
Bacto Agar

A simple anaerobic recovery-enrichment system, semisolid Penn State University (ssPSU) broth, that enhances recovery of heat-injured Listeria monocytogenes, was rapidly achieved in 10-ml screw-capped tubes by adding Bacto-agar (2.5 g/liter) and L-cysteine (0.5 g/liter) to Penn State University broth. Glucose was removed from the formulation for ssPSU broth to prevent the growth of thermoduric lactobacilli. Ferric ammonium citrate was added to ssPSU broth to detect esculin hydrolysis and to indicate the presumptive presence of L. monocytogenes. Replacement of phosphate buffer with 3-[N-morpholino]propanesulfonic acid (MOPS) buffer and addition of magnesium sulfate (15 mM) enhanced recovery and detection of L. monocytogenes heat treated at 62.8°C for 20 min. D-Serine, at a concentration of 150 mM, was found to inhibit germination of Bacillus spp. spores but did not inhibit severely heat-injured L. monocytogenes. Finally, ssPSU broth was modified (to mPSU broth) to contain the following: (i) Bacto-agar, 2.5 g/liter; (ii) ferric ammonium citrate, 0.5 g/liter; (iii) MOPS buffer, pH 7.0; (iv) D-serine, 13.7 g/liter; (v) D-alanine, 11.6 g/liter; and (iv) magnesium sulfate, 1.81 g/liter. Incubation temperature significantly affected the recovery and detection of severely heat-injured L. monocytogenes. L. monocytogenes that were heat challenged in filter-sterilized whole milk at 62.8°C for 20, 25, and 30 min could not be detected at incubation temperatures ≥30°C but were consistently detected after incubation at 25°C for 174, 199, and 330 h, respectively. Heat-injured cells of L. monocytogenes that were added to various commercial brands of pasteurized whole milk were also detected using mPSU broth. When clostridial spores (104 spores per ml) were added to filter-sterilized milk containing either heat-injured or non–heat-injured L. monocytogenes, only the latter could be detected in mPSU broth. The mPSU broth system requires no purging with nitrogen gas to create anaerobic conditions and permits recovery, growth, and detection of L. monocytogenes in one vessel in the presence of thermoduric background microflora commonly found in pasteurized milk.

scholarly journals A study on the aspects of pharmacoepidemiology and pharmacohaemovigilance of ferrous ascorbate, ferrous fumarate, ferrous sulphate and ferric ammonium citrate, among the rural anaemic women, in the Indian spectrum

2019 ◽  
Vol 8 (12) ◽  
pp. 2751
Author(s):  
Moumita Hazra
Keyword(s):  
Ferrous Sulphate ◽  
Haemoglobin Concentration ◽  
Significant Rise ◽  
Demographic Characteristics ◽  
Health Concern ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Ferrous Fumarate ◽  
Ferrous Ascorbate ◽  
Ferric Ammonium

Background: Anaemia is a global health concern, associated with increased maternal and perinatal mortality, preterm delivery, low birth weight, extreme fatigue and impaired immune system; and controlled by oral haematinics; with a rise in haemoglobin concentration. The objective was to examine the various aspects of pharmacoepidemiology and pharmacohaemovigilance of oral haematinics, among the anaemic women population, in rural India.Methods: This was a multi-centre, retrospective, observational and analytical study of the hospital medical records of 250 anaemic patients, who were allocated into group A of 125 patients within 15-21 years and group B of 125 patients within 22-35 years. The patients were prescribed oral haematinics, containing 60 mg of elemental iron, thrice daily, with meals. The various aspects of pharmacoepidemiology and pharmacohaemovigilance of ferrous ascorbate, ferrous sulphate, ferrous fumarate and ferric ammonium citrate, including patients’ demographic characteristics, anaemic symptoms assessment, prescription patterns, and safety assessment, on 1st, 2nd, 3rd months and follow-up visits, were recorded and thoroughly analysed..Results: In groups A and B, the demographic characteristics of the patients were comparable; ferrous ascorbate was the most commonly prescribed oral haematinic, followed by ferrous sulphate, ferrous fumarate and ferric ammonium citrate, which controlled mild to moderate iron deficiency anaemia, with a gradual significant rise in haemoglobin concentration, in the successive 3 months; and adverse effects were observed to be statistically non-significant in either group.Conclusions: The different aspects of pharmacoepidemiology and pharmacohaemovigilance in the study established that the oral haematinics were reasonably beneficial and safe among the anaemic women population, in rural India.

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