LOSS OF VIABILITY BY STAPHYLOCOCCUS AUREUS IN ACIDIFIED MEDIA

1972 ◽  
Vol 35 (9) ◽  
pp. 548-555 ◽  
Author(s):  
T. E. Minor ◽  
E. H. Marth
Keyword(s):  
Staphylococcus Aureus ◽  
Food Processing ◽  
Stationary Growth Phase ◽  
Low Ph ◽  
Lag Phase ◽  
Stationary Growth ◽  
Nutrient Media ◽  
Ph Values ◽  
High And Low Temperatures ◽  
Subsequent Acid

Determinations were made on the extent to which Staphylococcus aureus was inactivated [inability to grow on Trypticase Soy agar (TSA)] or injured [inability to grow on TSA + 7% added NaCl (TSAS)] in acidic artificial media and how inactivation was affected when some stresses common to food processing operations were inflicted on the organism. When cells were held in TS broth at >PH 6 (24 hr, 37 C), presence of 7% salt added to the medium did not affect inactivation of staphylococci; but, at ≤pH 5, salt enhanced inactivation. Cells that survived this treatment were not sensitive to salt present in the plating medium, whereas staphylococci from the stationary growth phase (TS broth, pH 7) were sensitive to salt. Cells exposed to low pH were only slightly more sensitive to salt when plated on TSAS than were cells held at pH 7. Exposure of organisms to salt did not render them appreciably more sensitive to subsequent acid treatment than were untreated organisms. Freezing (−30 C, 24 hr) did not substantially enhance inactivation of S. aureus at low pH but injury was greatly increased. A sublethal heat treatment (60 C, 15 min) failed to markedly enhance injury or death of cells at low pH values. Exposure to high and low temperatures failed to increase susceptibility of staphylococci to acid and acid-treated cells were no more sensitive to effects of these temperatures than were untreated cells. Staphylococci exposed to a low pH exhibited an extended lag phase when transferred to neutral nutrient media.

The Effect of Adding Blood on the Virulence Genes Expression of Staphylococcus aureus in Exponential and Stationary Growth Phase

2017 ◽  
Vol 10 (6) ◽  
Author(s):  
Hadi Koohsari ◽  
Ezzat Allah Ghaemi ◽  
Noor Amir Mozaffari ◽  
Abdolvahhab Moradi ◽  
Maryam Sadegh-Sheshpoli ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Phase ◽  
Virulence Genes ◽  
Stationary Growth Phase ◽  
Stationary Growth ◽  
Genes Expression

scholarly journals Two Novel Semisynthetic Lipoglycopeptides Active against Staphylococcus aureus Biofilms and Cells in Late Stationary Growth Phase

2021 ◽  
Vol 14 (11) ◽  
pp. 1182
Author(s):  
Vladimir Vimberg ◽  
Leona Zieglerova ◽  
Aninda Mazumdar ◽  
Zsolt Szűcs ◽  
Aniko Borbás ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Growth Phase ◽  
Stationary Growth Phase ◽  
Glycopeptide Antibiotics ◽  
Stationary Growth ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
New Antibiotics

The increase in antibiotic resistance among Gram-positive bacteria underscores the urgent need to develop new antibiotics. New antibiotics should target actively growing susceptible bacteria that are resistant to clinically accepted antibiotics including bacteria that are not growing or are protected in a biofilm environment. In this paper, we compare the in vitro activities of two new semisynthetic glycopeptide antibiotics, MA79 and ERJ390, with two clinically used glycopeptide antibiotics—vancomycin and teicoplanin. The new antibiotics effectively killed not only exponentially growing cells of Staphylococcus aureus, but also cells in the stationary growth phase and biofilm.

scholarly journals Deletion of the Alternative Sigma Factor ςB in Staphylococcus aureus Reveals Its Function as a Global Regulator of Virulence Genes

1998 ◽  
Vol 180 (18) ◽  
pp. 4814-4820 ◽  
Author(s):  
Ines Kullik ◽  
Philipp Giachino ◽  
Thomas Fuchs
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Genes ◽  
Laboratory Strain ◽  
Stationary Growth Phase ◽  
Wild Type ◽  
Global Regulator ◽  
Stationary Growth ◽  
Defective Mutant ◽  
Increased Sensitivity ◽  
Type Strains

ABSTRACT A deletion of the sigB operon was constructed in three genetically distinct Staphylococcus aureus strains, and the phenotypes of the resulting mutants were analyzed. Compared to the corresponding wild-type strains, the ΔsigB mutants showed reduced pigmentation, accelerated sedimentation, and increased sensitivity to hydrogen peroxide during the stationary growth phase. A cytoplasmic protein missing in the ΔsigB mutants was identified as alkaline shock protein 23, and an extracellular protein excreted at higher levels in one of the ΔsigB mutants was identified as staphylococcal thermonuclease. Interestingly, mostsigB deletion phenotypes were only seen in S. aureus COL and Newman and not in 8325, which was found to contain an 11-bp deletion in the regulator gene rsbU. Taken together, our results show that ςB is a global regulator which modulates the expression of several virulence factors in S. aureus and that laboratory strain 8325 is a ςB-defective mutant.

scholarly journals Biological Approach to Modeling of Staphylococcus aureus High-Hydrostatic-Pressure Inactivation Kinetics

2010 ◽  
Vol 76 (21) ◽  
pp. 6982-6990 ◽  
Author(s):  
Guillermo Cebrián ◽  
Chris W. Michiels ◽  
Pilar Mañas ◽  
Santiago Condón
Keyword(s):  
Staphylococcus Aureus ◽  
Sodium Chloride ◽  
Hydrostatic Pressure ◽  
Growth Phase ◽  
High Hydrostatic Pressure ◽  
Stationary Growth Phase ◽  
Inactivation Rate ◽  
Inactivation Kinetics ◽  
Stationary Growth ◽  
Tail Region

ABSTRACT Graphs for survival under high hydrostatic pressure (450 MPa; 25°C; citrate-phosphate buffer, pH 7.0) of stationary-growth-phase cells of eight Staphylococcus aureus strains were found to be nonlinear. The strains could be classified into two groups on the basis of the shoulder length. Some of them showed long shoulders of up to 20 min at 450 MPa, while others had shoulders of <3.5 min. All strains showed tails. No significant differences in the inactivation rate were found during the log-linear death phase among the eight strains. The entry into stationary growth phase resulted both in an increase in shoulder length and in a decrease in the inactivation rate. However, whereas shoulder length proved to depend on sigma B factor activity, the inactivation rate did not. Recovery in anaerobiosis decreased the inactivation rate but did not affect the shoulder length. Addition of the minimum noninhibitory concentration of sodium chloride to the recovery medium resulted in a decrease in shoulder length and in an increase in the inactivation rate for stationary-growth-phase cells. In the tail region, up to 90% of the population remained sensitive to sodium chloride.

Antibacterial Protection by Enterocin AS-48 in Sport and Energy Drinks with Less Acidic pH Values

2009 ◽  
Vol 72 (4) ◽  
pp. 881-884 ◽  
Author(s):  
PILAR MARTINEZ VIEDMA ◽  
HIKMATE ABRIOUEL ◽  
NABIL BEN OMAR ◽  
ROSARIO LUCAS LÓPEZ ◽  
EVA VALDIVIA ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Dental Health ◽  
Energy Drinks ◽  
Low Ph ◽  
Final Concentration ◽  
Acidic Ph ◽  
Time Increase ◽  
Natural Preservative ◽  
Ph Values

The low pH and acid content found in sports and energy drinks are a matter of concern in dental health. Raising the pH may solve this problem, but at the same time increase the risks of spoilage or presence of pathogenic bacteria. In the present study, commercial energy drinks were adjusted to pH 5.0 and challenged with Listeria monocytogenes (drinks A to F), Staphylococcus aureus, Bacillus cereus, and Bacillus licheniformis (drink A) during storage at 37°C. L. monocytogenes was able to grow in drink A and survived in drinks D and F for at least 2 days. Addition of enterocin AS-48 (1 μg/ml final concentration) rapidly inactivated L. monocytogenes in all drinks tested. S. aureus and B. cereus also survived quite well in drink A, and were completely inactivated by 12.5 μg/ml enterocin AS-48 after 2 days of storage or by 25 μg/ml bacteriocin after 1 day. B. licheniformis was able to multiply in drink A, but it was completely inactivated by 5 μg/ml enterocin AS-48 after 2 days of storage or by 12.5 μg/ml bacteriocin after 1 day. Results from the present study suggest that enterocin AS-48 could be used as a natural preservative against these target bacteria in less acidic sport and energy drinks.

scholarly journals Strategies to Encapsulate the Staphylococcus aureus Bacteriophage phiIPLA-RODI

Viruses ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 495 ◽  
Author(s):  
Eva González-Menéndez ◽  
Lucía Fernández ◽  
Diana Gutiérrez ◽  
Daniel Pando ◽  
Beatriz Martínez ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Particle Size ◽  
Food Processing ◽  
Antimicrobial Properties ◽  
Low Ph ◽  
Lower Percentage ◽  
Vesicle Formation ◽  
Food Processing Industry ◽  
Processing Industry ◽  
Improve Stability

The antimicrobial properties of bacteriophages make them suitable food biopreservatives. However, such applications require the development of strategies that ensure stability of the phage particles during food processing. In this study, we assess the protective effect of encapsulation of the Staphylococcus aureus bacteriophage phiIPLA-RODI in three kinds of nanovesicles (niosomes, liposomes, and transfersomes). All these systems allowed the successful encapsulation of phage phiIPLA-RODI with an efficiency ranged between 62% and 98%, regardless of the concentration of components (like phospholipids and surfactants) used for vesicle formation. Only niosomes containing 30 mg/mL of surfactants exhibited a slightly lower percentage of encapsulation. Regarding particle size distribution, the values determined for niosomes, liposomes, and transfersomes were 0.82 ± 0.09 µm, 1.66 ± 0.21 µm, and 0.55 ± 0.06 µm, respectively. Importantly, bacteriophage infectivity was maintained during storage for 6 months at 4 °C for all three types of nanovesicles, with the exception of liposomes containing a low concentration of components. In addition, we observed that niosomes partially protected the phage particles from low pH. Thus, while free phiIPLA-RODI was not detectable after 60 min of incubation at pH 4.5, titer of phage encapsulated in niosomes decreased only 2 log units. Overall, our results show that encapsulation represents an appropriate procedure to improve stability and, consequently, antimicrobial efficacy of phages for application in the food processing industry.

scholarly journals EttA is likely non-essential in Staphylococcus aureus persistence, fitness or resistance to antibiotics

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Michal Meir ◽  
Anna Rozenblit ◽  
Simona Fliger ◽  
Yuval Geffen ◽  
Daniel Barkan
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Growth Phase ◽  
Cell Formation ◽  
Stationary Growth Phase ◽  
Clinical Isolates ◽  
Beta Lactam ◽  
Stationary Growth ◽  
Mechanisms Of Persistence

Abstract Background Tolerance to antibiotics and persistence are associated with antibiotic treatment failures, chronic-relapsing infections, and emerging antibiotic resistance in various bacteria, including Staphylococcus aureus. Mechanisms of persistence are largely unknown, yet have been linked to physiology under low-ATP conditions and the metabolic-inactive state. EttA is an ATP-binding cassette protein, linked in Eschrechia coli to ribosomal hibernation and fitness in stationary growth phase, yet its role in S. aureus physiology is unknown. Results Using whole genome sequencing (WGS) of serial clinical isolates, we identified an EttA-negative S. aureus mutant (ettAstop), and its isogenic wild-type counterpart. We used these two isogenic clones to investigate the role of ettA in S. aureus physiology in starvation and antibiotic stress, and test its role in persistence and antibiotic tolerance. ettAstop and its WT counterpart were similar in their antibiotic resistance profiles to multiple antibiotics. Population dynamics of ettAstop and the WT were similar in low-nutrient setting, with similar recovery from stationary growth phase or starvation. Supra-bacteriocidal concentration of cefazolin had the same killing effect on ettAstop and WT populations, with no difference in persister formation. Conclusions Lack of ettA does not affect S. aureus antibiotic resistance, beta-lactam tolerance, resilience to starvation or fitness following starvation. We conclude the role of ettA in S. aureus physiology is limited or redundant with another, unidentified gene. WGS of serial clinical isolates may enable investigation of other single genes involved in S. aureus virulence, and specifically persister cell formation.

scholarly journals Efficacy of Daptomycin in Implant-Associated Infection Due to Methicillin-Resistant Staphylococcus aureus: Importance of Combination with Rifampin

2009 ◽  
Vol 53 (7) ◽  
pp. 2719-2724 ◽  
Author(s):  
Anne-Kathrin John ◽  
Daniela Baldoni ◽  
Manuel Haschke ◽  
Katharina Rentsch ◽  
Patrick Schaerli ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Phase ◽  
Treatment Options ◽  
Stationary Growth Phase ◽  
Infection Model ◽  
Logarithmic Phase ◽  
High Dose ◽  
Cure Rate ◽  
Stationary Growth ◽  
Time Kill

ABSTRACT Limited treatment options are available for implant-associated infections caused by methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). We compared the activity of daptomycin (alone and with rifampin [rifampicin]) with the activities of other antimicrobial regimens against MRSA ATCC 43300 in the guinea pig foreign-body infection model. The daptomycin MIC and the minimum bactericidal concentration in logarithmic phase and stationary growth phase of MRSA were 0.625, 0.625, and 20 μg/ml, respectively. In time-kill studies, daptomycin showed rapid and concentration-dependent killing of MRSA in stationary growth phase. At concentrations above 20 μg/ml, daptomycin reduced the counts by >3 log10 CFU/ml in 2 to 4 h. In sterile cage fluid, daptomycin peak concentrations of 23.1, 46.3, and 53.7 μg/ml were reached 4 to 6 h after the administration of single intraperitoneal doses of 20, 30, and 40 mg/kg of body weight, respectively. In treatment studies, daptomycin alone reduced the planktonic MRSA counts by 0.3 log10 CFU/ml, whereas in combination with rifampin, a reduction in the counts of >6 log10 CFU/ml was observed. Vancomycin and daptomycin (at both doses) were unable to cure any cage-associated infection when they were given as monotherapy, whereas rifampin alone cured the infections in 33% of the cages. In combination with rifampin, daptomycin showed cure rates of 25% (at 20 mg/kg) and 67% (at 30 mg/kg), vancomycin showed a cure rate of 8%, linezolid showed a cure rate of 0%, and levofloxacin showed a cure rate of 58%. In addition, daptomycin at a high dose (30 mg/kg) completely prevented the emergence of rifampin resistance in planktonic and adherent MRSA cells. Daptomycin at a high dose, corresponding to 6 mg/kg in humans, in combination with rifampin showed the highest activity against planktonic and adherent MRSA. Daptomycin plus rifampin is a promising treatment option for implant-associated MRSA infections.

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