What are the conditions that limit the effectiveness of microbial control?
Persister cells are medically important because they are associated with certain chronic infections, such as tuberculosis, that do not respond to antibiotic treatment. Sustaining Microbial Growth. The growth pattern shown in Figure 9.5 takes place in a closed environment; nutrients are not added and waste and dead cells are not removed. In many cases, though, it is …
What must happen for a microbial control technique to result in sterilization?
The prefix indicates the type of microbe or infectious agent killed by the treatment method: bactericides kill bacteria, viricides kill or inactivate viruses, and fungicides kill fungi. Other methods do not kill organisms but, instead, stop their growth, making their population static; such methods are identified by the suffix -stat (or -static ).
How effective are low temperatures for the growth of microorganisms?
The prefix indicates the type of microbe or infectious agent killed by the treatment method: bactericides kill bacteria, viricides kill or inactivate viruses, and fungicides kill fungi. Other methods do not kill organisms but, instead, stop their growth, making their population static; such methods are identified by the suffix -stat (or -static ).
Do antimicrobial agents have different effects on vegetative cells and endospores?
Growth of microbes will resume following the discontinuation of which type of treatment?-Bacteristatic-Fungistatic. Death for a microbe is defined as failure to _____. grow in a medium that should support its growth. Persister cells in a microbial population are _____.
What is the most effective treatment for controlling microbial growth?
Which processes are used in the prevention of microbial growth?
Which treatment can reduce microbial population?
Which two of the following are effective ways to control microorganisms?
Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeasts?
How are microorganisms destroyed by dry heat?
Should microbial growth be controlled?
How do antibiotics control microbial growth?
What is a solution that slows the growth of microorganisms called?
Which disinfectant is the most effective at stopping bacterial growth?
How is microbial growth controlled by the reduction of available water in food products?
Which drying method of microbial control can also be used to preserve microbial cultures?
What are the phases of growth in bacteria?
It has been determined that in a closed system or batch culture (no food added, no wastes removed) bacteria will grow in a predictable pattern, resulting in a growth curve composed of four distinct phases of growth: the lag phase, the exponential or log phase, the stationary phase, and the death or decline phase.
How is microbial growth measured?
While growth for muticelluar organisms is typically measured in terms of the increase in size of a single organism, microbial growth is measured by the increase in population, either by measuring the increase in cell number or the increase in overall mass.
Can yeast grow in wort?
Provided with the right conditions (food, correct temperature, etc) microbes can grow very quickly. Depending on the situation, this could be a good thing for humans (yeast growing in wort to make beer) or a bad thing (bacteria growing in your throat causing strep throat). It’s important to have knowledge of their growth, ...
Do bacteria reproduce asexually?
Bacteria and archaea reproduce asexually only, while eukartyotic microbes can engage in either sexual or asexual reproduction. Bacteria and archaea most commonly engage in a process known as binary fission, where a single cell splits into two equally sized cells.
How long does it take for an E. coli cell to divide?
The entire process or cell cycle can take as little as 20 minutes for an active culture of E. coli bacteria.
What is the lag phase of bacteria?
The lag phase is an adaptation period, where the bacteria are adjusting to their new conditions. The length of the lag phase can vary considerably, based on how different the conditions are from the conditions that the bacteria came from, as well as the condition of the bacterial cells themselves. Actively growing cells transferred from one type of media into the same type of media, with the same environmental conditions, will have the shortest lag period. Damaged cells will have a long lag period, since they must repair themselves before they can engage in reproduction.
What is the exponential phase of cell division?
Exponential or Log phase. Once cells have accumulated all that they need for growth, they proceed into cell division. The exponential or log phase of growth is marked by predictable doublings of the population, where 1 cell become 2 cells, becomes 4, becomes 8 etc. Conditions that are optimal for the cells will result in very rapid growth ...
What is an inanimate object that may harbor microbes and aid in their transmission called?
Inanimate items that may harbor microbes and aid in their transmission are called fomites . The level of cleanliness required for a fomite depends both on the item’s use and the infectious agent with which the item may be contaminated.
What is the suffix for microbial control?
Physical and chemical methods of microbial control that kill the targeted microorganism are identified by the suffix -cide (or -cidal ). The prefix indicates the type of microbe or infectious agent killed by the treatment method: bactericides kill bacteria, viricides kill or inactivate viruses, and fungicides kill fungi. Other methods do not kill organisms but, instead, stop their growth, making their population static; such methods are identified by the suffix -stat (or -static ). For example, bacteriostatic treatments inhibit the growth of bacteria, whereas fungistatic treatments inhibit the growth of fungi. Factors that determine whether a particular treatment is -cidal or -static include the types of microorganisms targeted, the concentration of the chemical used, and the nature of the treatment applied.
How old is Jenny from the hospital?
Jenny is a 46-year-old real estate agent who recently underwent a cholecystectomy (surgery to remove painful gallstones). The surgery was performed laparoscopically with the aid of a duodenoscope, a specialized endoscope that allows surgeons to see inside the body with the aid of a tiny camera. On returning home from the hospital, Jenny developed ...
How old is Jenny from the cholecystectomy?
Jenny is a 46-year-old real estate agent who recently underwent a cholecystectomy (surgery to remove painful gallstones). The surgery was performed laparoscopically with the aid of a duodenoscope, a specialized endoscope that allows surgeons to see inside the body with the aid of a tiny camera. On returning home from the hospital, Jenny developed abdominal pain and a high fever. She also experienced a burning sensation during urination and noticed blood in her urine. She notified her surgeon of these symptoms, per her postoperative instructions.
What bacteria causes botulism?
For example, foods preserved by canning often become contaminated with the bacterium Clostridium botulinum, which produces the neurotoxin that causes botulism. Because C. botulinum can produce endospore s that can survive harsh conditions, extreme temperatures and pressures must be used to eliminate the endospores.
What is a BSL-2 lab?
BSL-2 laboratories are equipped with self-closing doors, an eyewash station, and an autoclave, which is a specialized device for sterilizing materials with pressurized steam before use or disposal. BSL-1 laboratories may also have an autoclave. BSL-3 agents have the potential to cause lethal infections by inhalation.
What is directional airflow?
These laboratories are equipped with directional airflow, meaning that clean air is pulled through the laboratory from clean areas to potentially contaminated areas. This air cannot be recirculated, so a constant supply of clean air is required. Figure 1.
What is the suffix for microbial control?
Physical and chemical methods of microbial control that kill the targeted microorganism are identified by the suffix -cide (or -cidal ). The prefix indicates the type of microbe or infectious agent killed by the treatment method: bactericides kill bacteria, viricides kill or inactivate viruses, and fungicides kill fungi. Other methods do not kill organisms but, instead, stop their growth, making their population static; such methods are identified by the suffix -stat (or -static ). For example, bacteriostatic treatments inhibit the growth of bacteria, whereas fungistatic treatments inhibit the growth of fungi. Factors that determine whether a particular treatment is -cidal or -static include the types of microorganisms targeted, the concentration of the chemical used, and the nature of the treatment applied.
What bacteria causes botulism?
For example, foods preserved by canning often become contaminated with the bacterium Clostridium botulinum, which produces the neurotoxin that causes botulism. Because C. botulinum can produce endospore s that can survive harsh conditions, extreme temperatures and pressures must be used to eliminate the endospores.
How old is Roberta from the cholecystectomy?
Roberta is a 46-year-old real estate agent who recently underwent a cholecystectomy (surgery to remove painful gallstones). The surgery was performed laparoscopically with the aid of a duodenoscope, a specialized endoscope that allows surgeons to see inside the body with the aid of a tiny camera. On returning home from the hospital, Roberta developed abdominal pain and a high fever. She also experienced a burning sensation during urination and noticed blood in her urine. She notified her surgeon of these symptoms, per her postoperative instructions.
What is a BSL-2 lab?
BSL-2 laboratories are equipped with self-closing doors, an eyewash station, and an autoclave, which is a specialized device for sterilizing materials with pressurized steam before use or disposal. BSL-1 laboratories may also have an autoclave. BSL-3 agents have the potential to cause lethal infections by inhalation.
What is the chemical used to sterilize?
Chemicals that can be used to achieve sterilization are called sterilants . Sterilants effectively kill all microbes and viruses, and, with appropriate exposure time, can also kill endospores. For many clinical purposes, aseptic technique is necessary to prevent contamination of sterile surfaces.
Why is aseptic technique important?
For many clinical purposes, aseptic technique is necessary to prevent contamination of sterile surfaces. Aseptic technique involves a combination of protocols that collectively maintain sterility, or asepsis, thus preventing contamination of the patient with microbes and infectious agents.
What is sterilization protocol?
Sterilization protocols require procedures that are not practical, or necessary, in many settings. Various other methods are used in clinical and nonclinical settings to reduce the microbial load on items. Although the terms for these methods are often used interchangeably, there are important distinctions ( Figure 13.4 ).
What is antimicrobial therapy?
Antimicrobial agents are some of the most widely, and often injudiciously, used therapeutic drugs worldwide. Important considerations when prescribing antimicrobial therapy include obtaining an accurate diagnosis of infection; understanding the difference between empiric and definitive therapy; identifying opportunities to switch ...
What is the difference between antibacterial and bactericidal?
A commonly used distinction among antibacterial agents is that of bactericidal vs bacteriostatic agents. Bactericidal drugs, which cause death and disruption of the bacterial cell, include drugs that primarily act on the cell wall (eg, β-lactams), cell membrane (eg, daptomycin), or bacterial DNA (eg, fluoroquinolones).
When should empiric therapy be initiated?
In critically ill patients, such as those in septic shock, febrile neutropenic patients, and patients with bacterial meningitis, empiric therapy should be initiated immediately after or concurrently with collection of diagnostic specimens.
Why is combination therapy used for HIV?
This is why combination drug therapy is used as the standard for treatment of infections such as tuberculosis and the human immunodeficiency virus (HIV) when treatment duration is likely to be prolonged, resistance can emerge relatively easily, and therapeutic agents are limited.
What are the factors that determine the effectiveness of a disinfectant?
7) List the factors related to effective disinfection. 1. Careful attention should be paid to the properties and concentration of the disinfectant. to be used. 2. The presence of organic matter, degree of contact with microorganisms, and. temperature should also be considered. Evaluating a disinfectant. 1.
What are the effects of radiation?
The effects of radiation depend on its wavelength, intensity, and duration. 2. Ionizing radiation (gamma rays, X rays, and high-energy electrons) has a high degree. of penetration and exerts its effect primarily by ionizing water and forming highly.
What is the wavelength of UV radiation?
penetration and causes cell damage by making thymine dimmers in DNA that interfere. with DNA replication; the most effective germicidal wavelength is 260 nm.
What is thermal death time?
Thermal death time (TDT) is the length of time required to kill all bacteria in a liquid. culture at a given temperature. 5. Decimal reduction time (DRT) is the length of time in which 90% of a bacterial. population will be killed at a given temperature. 6.
Lag Phase
Exponential Or Log Phase
- Once cells have accumulated all that they need for growth, they proceed into cell division. The exponential or log phaseof growth is marked by predictable doublings of the population, where 1 cell become 2 cells, becomes 4, becomes 8 etc. Conditions that are optimal for the cells will result in very rapid growth (and a steeper slope on the growth c...
Stationary Phase
- All good things must come to an end (otherwise bacteria would equal the mass of the Earth in 7 days!). At some point the bacterial population runs out of an essential nutrient/chemical or its growth is inhibited by its own waste products (it is a closed container, remember?) or lack of physical space, causing the cells to enter into the stationary phase. At this point the number of n…
Death Or Decline Phase
- In the last phase of the growth curve, the death or decline phase, the number of viable cells decreases in a predictable (or exponential) fashion. The steepness of the slope corresponds to how fast cells are losing viability. It is thought that the culture conditions have deteriorated to a point where the cells are irreparably harmed, since cells collected from this phase fail to show gr…