FACTORS IN THE ECOSYSTEM OF FOOD PROCESSING EQUIPMENT CONTRIBUTING TO OUTGROWTH OF MICROORGANISMS ON STAINLESS STEEL SURFACES1

1971 ◽  
Vol 34 (12) ◽  
pp. 569-573 ◽  
Author(s):  
R. B. Maxcy
Keyword(s):  
Stainless Steel ◽  
Water Loss ◽  
Raw Milk ◽  
Solute Concentration ◽  
Plate Count ◽  
Laboratory System ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Sterile Phosphate Buffer ◽  
Mechanical Handling

A laboratory system using 1 cm2 pieces of stainless steel with controlled temperature, humidity, and inocula was used to study the fate of the microflora of dairy origin on various films. Metal squares were treated to simulate incomplete cleaning, then inoculated with raw milk. After incubation for 16 hr at 80, 86, 93, or 100% RH, the microflora was recovered in sterile phosphate buffer and evaluated using the standard plate count method. Isolates from countable plates were observed for general characterization. Humidity of the ecosystem was a major factor in rate of water loss from a film. Available water, and indirectly the solute concentration, influenced the microenvironment and the resulting population density of microorganisms. Likewise, the microenvironment had a selective effect on outgrowth of bacteria, because of varying sensitivity of bacteria to drying and solute concentration. The gram-negative bacteria were inhibited at a lower humidity (80% RH), while the higher humidities (93 or 100% RH) provided sufficient water for abundant outgrowth. Reduction of area of a film exposed to air reduced water loss and provided protection for harborage of microorganisms. Pre-soiling prior to addition of a film of milk decreased the rate of water loss from the film and increased bacterial growth. Induced lipolysis within a film of milk influenced outgrowth of bacteria with an inhibitory effect on gram-positive types. Results indicate that modem closed systems and extensive mechanical handling of milk may be favoring growth of undesirable gram-negative bacteria, e.g., coliforms and psychrotrophs.

scholarly journals Whole-Genome Sequencing of Gram-Negative Bacteria Isolated From Bovine Mastitis and Raw Milk: The First Emergence of Colistin mcr-10 and Fosfomycin fosA5 Resistance Genes in Klebsiella pneumoniae in Middle East

2021 ◽  
Vol 12 ◽  
Author(s):  
Yasmine H. Tartor ◽  
Norhan K. Abd El-Aziz ◽  
Rasha M. A. Gharieb ◽  
Hend M. El Damaty ◽  
Shymaa Enany ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Klebsiella Pneumoniae ◽  
Genome Sequencing ◽  
Bovine Milk ◽  
Bovine Mastitis ◽  
Raw Milk ◽  
Whole Genome ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli

Antimicrobial resistance is a major concern in the dairy industry. This study investigated the prevalence, antimicrobial resistance phenotypes, and genome sequencing of Gram-negative bacteria isolated from clinical (n = 350) and subclinical (n = 95) bovine mastitis, and raw unpasteurized milk (n = 125). Klebsiella pneumoniae, Aeromonas hydrophila, Enterobacter cloacae (100% each), Escherichia coli (87.78%), and Proteus mirabilis (69.7%) were the most prevalent multidrug-resistant (MDR) species. Extensive drug-resistance (XDR) phenotype was found in P. mirabilis (30.30%) and E. coli (3.33%) isolates. Ten isolates (four E. coli, three Klebsiella species and three P. mirabilis) that displayed the highest multiple antibiotic resistance (MAR) indices (0.54–0.83), were exposed to whole-genome sequencing (WGS). Two multilocus sequence types (MLST): ST2165 and ST7624 were identified among the sequenced E. coli isolates. Three E. coli isolates (two from clinical mastitis and one from raw milk) belonging to ST2165 showed similar profile of plasmid replicon types: IncFIA, IncFIB, IncFII, and IncQ1 with an exception to an isolate that contained IncR, whereas E. coli ST7624 showed a different plasmid profile including IncHI2, IncHI2A, IncI1α, and IncFII replicon types. ResFinder findings revealed the presence of plasmid-mediated colistin mcr-10 and fosfomycin fosA5 resistance genes in a K. pneumoniae (K1) isolate from bovine milk. Sequence analysis of the reconstructed mcr-10 plasmid from WGS of K1 isolate, showed that mcr-10 gene was bracketed by xerC and insertion sequence IS26 on an IncFIB plasmid. Phylogenetic analysis revealed that K1 isolate existed in a clade including mcr-10-harboring isolates from human and environment with different STs and countries [United Kingdom (ST788), Australia (ST323), Malawi (ST2144), Myanmar (ST705), and Laos (ST2355)]. This study reports the first emergence of K. pneumoniae co-harboring mcr-10 and fosA5 genes from bovine milk in the Middle East, which constitutes a public health threat and heralds the penetration of the last-resort antibiotics. Hence, prudent use of antibiotics in both humans and animals and antimicrobial surveillance plans are urgently required.

In Vitro antibacterial activity of lactic acid bacteria isolated from goat’s raw milk of Mostaganem (West Algeria) against Gram negative bacteria responsible for urinary tract infections

2016 ◽  
Vol 6 (1) ◽  
pp. 15-22
Author(s):  
Zergoug Amina ◽  
Cheriguene Abderrahim ◽  
Chougrani Fadela
Keyword(s):  
Antibacterial Activity ◽  
Lactic Acid ◽  
Urinary Tract ◽  
Lactic Acid Bacteria ◽  
Raw Milk ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Tract Infections ◽  
West Algeria

Urinary tract infections (UTI) are a serious bacterial pathological challenges all over the world, leading to respiratory infections, that’s why new strategies don’t cease to develop. Lactic acid bacteria having shown beneficial effects for years in various areas, may prove to be excellent candidates in medical field. The current research focused on the selection of lactic acid bacteria having the potential of an antibacterial activity against Gram negative bacteria responsible for UTI, for an eventual use as a therapeutic agent. A total of 40 isolates were isolated from goat’s raw milk of Mostaganem (West Algeria). In vitro tests were conducted in order to determine the efficiency of the isolates to produce antibacterial agents in interaction with uropathogens. Among 40 isolates, only 10 isolates identified as Lactobacilli and Lactococci were performant. The Screening showed that the inhibitor agent was proteinaceous substance. Therfore, it is noted that a treatment with presence of LAB is very encouraging as a result of the production of bacteriocin-like substance. On the other hand, LAB can be considered as a good alter-native to the large extent to the antibiotics in the treatment of UTI.

Gram-Negative Bacteria in Raw Milk

1969 ◽  
Vol 2 (2) ◽  
pp. 69-71 ◽  
Author(s):  
G. Blankenagel ◽  
I. Okello-Uma
Keyword(s):  
Raw Milk ◽  
Gram Negative Bacteria ◽  
Gram Negative

Bactericidal Properties of Ozone and Its Potential Application as a Terminal Disinfectant

2000 ◽  
Vol 63 (8) ◽  
pp. 1100-1106 ◽  
Author(s):  
GINNY MOORE ◽  
CHRIS GRIFFITH ◽  
ADRIAN PETERS
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Food Industry ◽  
Yeast Cells ◽  
Ozone Exposure ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Uht Milk ◽  
Bactericidal Properties ◽  
Gram Negative Organisms

The efficacy of ozone as a terminal disinfectant was evaluated under laboratory conditions. Different microorganisms of importance to the food industry were inoculated onto stainless steel squares and incubated at various temperatures and relative humidities for up to 4 h. Survival of microorganisms from these controls was compared with identically incubated squares exposed to ozone. Exposure of the contaminated surfaces to ozone (2 ppm for 4 h) resulted in a reduction in microbial viability that ranged, depending on organism type, from 7.56 to 2.41 log values. For all the microorganisms tested, this loss in viability was significantly greater (P < 0.05) than that observed in the absence of ozone. Gram-negative bacteria were more sensitive to ozone than gram-positive organisms; bacteria were more sensitive than the yeast strain tested. Exposure to ozone (2 ppm for 4 h) in the presence of ultra-high temperature (UHT) milk resulted in a reduction in bacterial viability that ranged from 5.64 to 1.65 log values. In most cases, this reduction was significantly less (P < 0.05) than that achieved in the absence of organic material, although still significantly greater (P < 0.05) than that observed in the absence of ozone. The presence of a meat-based broth reduced the effectiveness of ozone to a greater extent, although the number of surviving gram-negative organisms was still significantly less (P < 0.05) than in the absence of ozone. Less than 1 log unit of yeast cells was destroyed when exposed to ozone in the presence of UHT milk or meat-based broth. Results of this investigation suggest that if applied after adequate cleaning ozone could be used as an effective disinfectant.

scholarly journals Virulence Determinants and Plasmid-Mediated Colistin Resistance mcr Genes in Gram-Negative Bacteria Isolated From Bovine Milk

2021 ◽  
Vol 11 ◽  
Author(s):  
Yasmine H. Tartor ◽  
Rasha M. A. Gharieb ◽  
Norhan K. Abd El-Aziz ◽  
Hend M. El Damaty ◽  
Shymaa Enany ◽  
...  
Keyword(s):  
Virulence Genes ◽  
Raw Milk ◽  
Subclinical Mastitis ◽  
Clinical Mastitis ◽  
Gram Negative Bacteria ◽  
Colistin Resistance ◽  
Genetic Characteristics ◽  
Gram Negative ◽  
E Coli ◽  
Resistant Strains

A major increase of bacterial resistance to colistin, a last-resort treatment for severe infections, was observed globally. Using colistin in livestock rearing is believed to be the ground of mobilized colistin resistance (mcr) gene circulation and is of crucial concern to public health. This study aimed to determine the frequency and virulence characteristics of colistin-resistant Gram-negative bacteria from the milk of mastitic cows and raw unpasteurized milk in Egypt. One hundred and seventeen strains belonging to Enterobacteriaceae (n = 90), Pseudomonas aeruginosa (n = 10), and Aeromonas hydrophila (n = 17) were screened for colistin resistance by antimicrobial susceptibility testing. The genetic characteristics of colistin-resistant strains were investigated for mcr-1–9 genes, phylogenetic groups, and virulence genes. Moreover, we evaluated four commonly used biocides in dairy farms for teat disinfection toward colistin-resistant strains. Multidrug-resistant (MDR) and extensive drug-resistant (XDR) phenotypes were detected in 82.91% (97/117) and 3.42% (4/117) of the isolates, respectively. Of the 117 tested isolates, 61 (52.14%) were colistin resistant (MIC >2 mg/L), distributed as 24/70 (34.29%) from clinical mastitis, 10/11 (90.91%) from subclinical mastitis, and 27/36 (75%) from raw milk. Of these 61 colistin-resistant isolates, 47 (19 from clinical mastitis, 8 from subclinical mastitis, and 20 from raw milk) harbored plasmid-borne mcr genes. The mcr-1 gene was identified in 31.91%, mcr-2 in 29.79%, mcr-3 in 34.04%, and each of mcr-4 and mcr-7 in 2.13% of the colistin-resistant isolates. Among these isolates, 42.55% (20/47) were E. coli, 21.28% (10/47) A. hydrophila, 19.12% (9/47) K. pneumoniae, and 17.02% (8/47) P. aeruginosa. This is the first report of mcr-3 and mcr-7 in P. aeruginosa. Conjugation experiments using the broth-mating technique showed successful transfer of colistin resistance to E. coli J53-recipient strain. Different combinations of virulence genes were observed among colistin-resistant isolates with almost all isolates harboring genes. Hydrogen peroxide has the best efficiency against all bacterial isolates even at a low concentration (10%). In conclusion, the dissemination of mobile colistin resistance mcr gene and its variants between MDR- and XDR-virulent Gram-negative isolates from dairy cattle confirms the spread of mcr genes at all levels; animals, humans, and environmental, and heralds the penetration of the last-resort antimicrobial against MDR bacteria. Consequently, a decision to ban colistin in food animals is urgently required to fight XDR and MDR bacteria.

scholarly journals EFFECT OF SOLUTE CONCENTRATION AND PRE-SOIL INTERACTION ON THE MICROFLORA OF DAIRY ORIGIN ON STAINLESS STEEL SURFACES1

1970 ◽  
Vol 33 (12) ◽  
pp. 541-544 ◽  
Author(s):  
H. M. Barnhart ◽  
R. B. Maxcy ◽  
C. E. Georgi
Keyword(s):  
Stainless Steel ◽  
Water Loss ◽  
Food Processing ◽  
Solute Concentration ◽  
Moisture Loss ◽  
Stainless Steel Surface ◽  
Dairy Food ◽  
Temperature And Humidity ◽  
Closed Systems ◽  
Steel Surfaces

Use of modern dairy food processing equipment creates a complex microenvironment. Closed systems reduce air drying. The rate and extent of drying are dependent on temperature and humidity of the environment. These factors were studied to determine their impact on the microflora of films of milk on stainless steel surfaces. An ecosystem was established to simulate dairy food equipment by using 1cm2 pieces of stainless steel in controlled humidity chambers. Presoiling water loss from a film of milk, and solute concentration were studied to determine their influence on the fate of the microflora. Temperature and humidity of the atmosphere influenced the rate of moisture loss from films. Pre-soiling reduced the rate of water loss from films of milk sufficiently to allow bacterial growth at 12–80% relative humidity (RH). Results indicate bacteria can grow in a film placed in humidities well below the 95% RH limit previously projected. Apparently the substrate is influenced by interaction of the milk film and the stainless steel surface.

Comparison of Media for Determining Temperature Abuse of Fresh Broiler Carcasses Using Impedance Microbiology

1995 ◽  
Vol 58 (10) ◽  
pp. 1124-1128 ◽  
Author(s):  
SCOTT M. RUSSELL ◽  
DANIEL L. FLETCHER ◽  
NELSON A. COX
Keyword(s):  
Broiler Chicken ◽  
Brain Heart Infusion ◽  
Plate Count ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
Plate Count Agar ◽  
Processing Plants ◽  
Microbiological Techniques ◽  
The Ideal

Experiments were conducted to determine the ideal medium for detection of temperature abuse of fresh broiler chicken using impedance microbiological techniques. In three separate trials, 15 ready-to-cook broiler chicken carcasses were obtained from the chiller exit of three separate processing plants. Five carcasses were sampled immediately (day 0), 5 carcasses were sampled after temperature abusing at 25°C for 12 h and holding at 3°C for 6 days (temperature abused), and the remaining 5 carcasses were sampled after holding at 3°C for 7 days (day 7 controls). Whole-carcass rinses were diluted by placing 1 ml from each carcass into 9 ml of each of the following media: (1) brain heart infusion broth (BHI), (2) EC broth with 3% added dextrose (ECD), (3) CM medium with 2% added dextrose (CMD), (4) EC broth (EC), and (5) CM medium (CM). The diluted samples were assayed in duplicate at 43°C using impedance microbiological techniques. Once a detection time (DT) was recorded, one ml of the sample was immediately recovered from the module well, diluted to 10−6, 10−7, and 10−8, and spread plated onto plate count agar. Two colonies from each carcass on plates with the highest dilution were randomly selected and identified. Since both gram-positive and gram-negative genera of bacteria were isolated from BHI-cultured carcass rinses and were responsible for changing the impedance of the medium, DTs were variable. EC and ECD media were not suitable for conducting temperature-abuse determinations. Using CMD medium to select for the growth of gram-negative bacteria, specifically E. coli, temperature-abuse determinations were more accurate than using a general medium, such as BHI. CMD appears to be the most effective medium tested to conduct temperature abuse determinations using impedance microbiological techniques.

Routine Limulus amoebocyte lysate (LAL) test for endotoxin determination in milk using a Toxinometer ET-201

1993 ◽  
Vol 60 (2) ◽  
pp. 223-228 ◽  
Author(s):  
Jozef Mottar ◽  
Jan De Block ◽  
Martine Merchiers ◽  
Kristien Vantomme ◽  
Renaat Moermans
Keyword(s):  
Raw Materials ◽  
Raw Material ◽  
Plate Count ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Uht Milk ◽  
Limulus Amoebocyte Lysate ◽  
Endotoxin Content ◽  
Initial Transmission

SummaryA rapid method of performing the Limulus amoebocyte lysate (LAL) test in milk is proposed using the Toxinometer ET-201. This instrument measured the increase in turbidity due to the interaction between the endotoxins of the Gram-negative bacteria and the LAL reagent, monitored the ratio Rt of the sequential to the initial transmission at 12 s intervais and quantified endotoxins by determination of the reaction time Tr required to obtain a 5% decrease in Rt. There was a good correlation between the toxinometrically determined endotoxin concentrations and the number of Gram-negative bacteria (SD, 0·18 log(plate count units)), and the repeatability (CV, 6·10%) was high. The assay may be useful for screening raw materials for UHT milk production, as the endotoxin content of the raw material is related to the rest proteinase activity in the UHT milk.

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