How does glutaraldehyde kill bacteria?

How does glutaraldehyde kill bacteria?

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How does glutaraldehyde kill bacteria?

After disinfecting, does it leave the corpses of the bacteria to count?

Does it leave bio-film in tact?

Gluteraldehyde interacts with amino groups to block the dynamic movements that biology requires.

Yes the corpses of the fixed bacteria can be counted and bio-films will be intact but the bacteria will be fixed in place.

Biofilms that are fixed with gluteraldehyde may shrink when prepared for imaging due to the effects of dehydration.

Disinfection: Methods and Uses

Disinfection is a process whereby pathogenic organisms, but not necessarily all microorganisms or spores, are destroyed. Disinfection may be accomplished by physical or chemical means.

  1. Types of organisms present: Bacterial spores such as Bacillus spp., are the most resistant, followed by mycobacteria (acid-fast bacilli). Younger cells are usually more readily destroyed than mature organisms.
  2. Number of organisms present (microbial load): Time necessary for killing microorganisms increases in direct proportion with the number of organisms (microbial load). This is particularly true of instruments contaminated with organic material such as blood, pus, or mucus.
  3. Concentration of disinfectant: Generally, higher concentration of chemical disinfectants has higher killing power. Over a short-range, a small increase in concentration leads to an exponential rise in effectiveness but beyond a certain point, an increase in concentration may not raise the killing rate. Sometimes, an agent is more effective at lower concentrations. For example, 70% ethyl alcohol is more effective as a disinfectant than 95% ethyl alcohol.
  4. Amount of organics (blood, mucus, pus) present: The organic material should be mechanically removed before chemical sterilization to decrease the microbial load. This is analogous to removing dried food from utensils before placing them in a dishwasher and is important for cold sterilization of instruments such as bronchoscopes.
  5. Length of contact time: More is the exposure time to sterilant/disinfectant, better is the efficacy.
  6. Type of water available (hard vs. soft): Hard water may reduce the rate of killing of microorganisms.
  7. Temperature and pH of the process: An increase in the temperature at which chemical acts often enhances its activity. A lower concentration of disinfectants can be used at a higher temperature. Heat kills more readily in acidic pH.
  8. Nature of surface to be disinfected (e.g., potential for corrosion porous vs. nonporous surface)


Glutaraldehyde, C5H8O2 or OCH(CH₂)₃CHO, is a transparent oily, liquid with a pungent odor. Exposure to glutaraldehyde may cause the following symptoms: throat and lung irritation, asthma and difficulty breathing, dermatitis, nasal irritation, sneezing, wheezing, burning eyes, and conjunctivitis. Workers may be harmed from exposure to glutaraldehyde. Workers can be exposed to glutaraldehyde through inhalation or skin contact. The level of exposure depends upon the dose, duration, and work being done.

Glutaraldehyde is used for a number of applications:

  • Disinfectant for surgical instruments that cannot be heat sterilized
  • A cross-linking and tanning agent
  • A biocide in metalworking fluids and in oil and gas pipelines
  • An antimicrobial in water-treatment systems
  • A slimicide in paper manufacturing
  • A preservative in cosmetics
  • A disinfectant in animal housing
  • A tissue fixative in histology and pathology labs
  • A hardening agent in the development of X-rays
  • In embalming solutions
  • In the preparation of grafts and bioprostheses
  • In various clinical applications

NIOSH recommends that employers use Hierarchy of Controls to prevent injuries. If you work in an industry that uses glutaraldehyde, please read chemical labels and the accompanying Safety Data Sheet for hazard information. Visit NIOSH&rsquos page on Managing Chemical Safety in the Workplace to learn more about controlling chemical workplace exposures.

The following resources provide information about occupational exposure to glutaraldehyde. Useful search terms for glutaraldehyde include &ldquoglutaric dialdehyde,&rdquo and &ldquo1,5-pentanedial.&rdquo

NIOSH Chemical Resources

The NIOSH Pocket Guide to Chemical Hazards (NPG) helps workers, employers, and occupational health professionals recognize and control workplace chemical hazards.

The NIOSH Manual of Analytical Methods (NMAM) is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.

The Health Hazard Evaluation Program (HHE) conducts onsite investigations of possible worker exposure to chemicals. Search the HHE database for more information on chemical topics.

Swollen lymph nodes after Covid vaccination could be mistaken for breast cancer

A commonplace, everyday act of killing bacteria using moist heat is boiling our drinking water.

Before we learn how to kill bacteria, we should know what bacteria are and why we need to kill them. Bacteria are single-celled prokaryotic microorganisms found mostly under the Eubacteria kingdom in the Linnaeus classification.

A prokaryotic organism does not have a nucleus or membrane-bound organelles in its cells. In contrast, humans, animals and plants are all eukaryotic organisms that have nuclei and membrane-bound organelles in their cells.

Bacteria are not visible to the naked eye – we must use a light microscope in order to see them. They are present everywhere. Many of them are harmless, while some are beneficial for the human body. But there are also many pathogenic, or harmful, bacteria that cause disease in humans.

We need to learn how to kill bacteria in order to prevent ourselves from getting harmful infections, to prevent spoilage of food, and to prevent contamination of materials used in pure culture work in laboratories.

Sterilisation and disinfection

The process of killing bacteria and other microorganisms either in a vegetative or a spore state, is known as sterilisation.

In other words, sterilisation refers to any process that eliminates, removes, kills or deactivates all forms of biological agents like fungi, bacteria, viruses, spore forms, prions and unicellular eukaryotic organisms like Plasmodium parasites.

These can be present in a specified region like a surface, a volume of fluid, medication, or in a compound like a biological culture media.

Meanwhile, disinfection is defined as the destruction of all pathogenic organisms or organisms capable of giving rise to infection. It is less effective than sterilisation as not all disinfectants can destroy spores.

Sterilisation involves many physical and chemical changes in a cell, which finally leads to the removal or destruction of that cell.

These changes include the destruction of the structure of the cell’s proteins (denaturation) at a high temperature, the alteration or disruption of a cell’s metabolic processes through chemicals, and damage of the cell’s nucleus through radiation.

Sterilisation can be brought about by many methods, including physical methods, irradiation, and chemical agents or disinfectants.

Killing agents

Red heat: This has its main application in the sterilisation of laboratory equipment such as wires, forceps and spatulas. These are held in the flame of a Bunsen burner until they are red hot. This method can be used in laboratories, hospitals and homes, but only for materials made of iron.

Flaming: Scalpels, needles, culture tube mouths, glass slides, cover slips and others can be sterilised by passing them a few times through a Bunsen flame without allowing them to become red hot.

This way the bacteria gets burnt by the direct flame. This method is applied to items that cannot be held in the flame for a longer time without melting.

Hot air steriliser (oven): This resembles the electric oven we use at home. It is used to sterilise glassware, forceps, scissors, scalpels, all glass syringes, swabs, some pharmaceutical products such as liquid paraffin, sulphonamides, dusting powder, fat, grease and others.

Commonly, sterilisation in the oven uses a temperature of 1,600°C for one to two hours, 1,700°C for one hour or 1,800°C for 30 minutes. We can sterilise glasses, plates and kitchen utensils in this way. The items need to be wrapped in aluminium foil before using the oven.

Infra-red radiation: The infra-red rays are directed from an electrically-heated element onto the objects to be sterilised. Heating at or above 2,000°C by infra-red in a vacuum is employed as a means of sterilising surgical instruments and glass syringes.

Using water and rays

Moist heat is used for the sterilisation of culture media and other liquids that need to retain their water content. This method is utilised by the autoclave, which is the most reliable method of killing bacteria and other microorganisms.

Autoclaving provides moist heat at a temperature higher than 1,000°C through steam that is under increased pressure. This machine is often used in laboratories and hospitals.

Another popular method of killing bacteria using moist heat is boiling. Many of us boil water for 15-20 minutes before drinking. However, we must remember that boiling can kill bacteria, but not all bacterial spores.

Meanwhile, radiation kills bacteria by causing damage to the cell itself, particularly its DNA. There are two types of radiation: ionising (e.g. gamma rays, x-rays) and non-ionising (e.g. ultraviolet).

Germicidal lamps that emit ultraviolet radiation are widely used in hospital operating rooms, aseptic filling rooms, the pharmaceutical industry, and the food or dairy industries for treatment of contaminated surfaces.

Chemical agents

The exposure of bacteria to chemical disinfectants produces a variety of effects, such as the disruption of cell processes, the separation of cell proteins from the cell, inactivation of enzymes in the cell and the leakage of amino acids from the cell.

A few common chemical disinfectants are:

Phenol and phenolic compounds

A 5% aqueous solution of phenol rapidly kills bacteria. It is widely used for decontamination of infective discharges (like pus), bathrooms, bedpans and hospital floors.

A 70% ethyl alcohol solution is among the most effective and frequently used agents for disinfection. It is widely used in reducing the microbial flora of skin to help prevent infection, e.g. before you receive an injection.

Iodine is one of the most effective germicidal agents. It is effective against all kinds of bacteria, as well as spores, fungi and viruses. It is used as a rapid skin disinfectant and is valuable for the preparation of the skin for surgery.

It can also be used at home to disinfect a wound before bandaging it. Iodine is also used for the disinfection of water and air, and sanitisation of food utensils.

Chlorine and chlorine compounds

These are used in water treatment, the food industry and medicine, as well as for sanitising dairy equipment and eating utensils, disinfecting open wounds, and treating athlete’s foot, among others.

Copper sulphate is much more effective against algae and moulds than bacteria. It is used in swimming pools and open water reservoirs to prevent algal growth.

Soaps reduce surface tension, thereby increasing the wetting power of water. Soapy water has the ability to emulsify and disperse oils and dirt. Bacteria will become enmeshed in the soap lather and removed by the rinse water. Several detergents are bactericidal and available commercially.


Formaldehyde in gas form is used for disinfection of enclosed areas, rooms, furniture etc. It can kill spores almost as readily as the vegetative forms of bacteria.


Glutaraldehyde kills bacteria and spores, and is effective against viruses. It is used in the medical field for sterilising urological instruments, lensed instruments, respiratory therapy equipment, cytoscopes, anaesthetic equipment etc.

Ethylene oxide

Ethylene oxide kills bacteria (and their endospores), mould and fungi. It is widely used to sterilise the majority of medical supplies such as bandages, sutures, endoscopes, stethoscope and surgical implements.

There are many factors that can influence the killing of bacteria. The time of exposure, temperature, concentration and pH of the disinfectants, as well as the number of bacteria present, need to be considered before we choose the method of killing bacteria.


Bordetella species are gram-negative bacteria that infect the respiratory tracts of mammals. The highly genetically conserved classical Bordetella species comprise B. pertussis and B. parapertussis, the etiological agents of whooping cough in humans [1], as well as B. bronchiseptica, which infects a variety of mammals and immunocompromised humans [1–3]. The major virulence genes in the classical bordetellae are regulated under the Bordetella virulence gene (BvgAS) two-component system, which senses environmental cues and controls transcription of over 100 virulence-associated factors [4,5]. The “Bvg positive (Bvg + ) phase” refers to the activated state of the BvgAS system [5,6] in which the expression of genes that have been shown to be necessary for mammalian respiratory tract infection and survival are induced [6–9]. In contrast, at lower temperatures, in the “Bvg negative (Bvg - ) phase,” the expression of virulence factors is repressed, and a similarly large set of genes, including those that enable flagella-mediated motility and growth in dilute nutrients, are specifically expressed [6,8,10]. Mutants that are locked in the Bvg - phase are rapidly cleared from inoculated animals, revealing the critical role of Bvg + “virulence factors” during infection [11]. In contrast, bacteria locked in the Bvg + phase efficiently infect hosts, indicating that the Bvg - phase is not required for successful interactions with the host. Explanations for the conservation of the large set of Bvg - genes include speculated roles for the Bvg - phase in survival in some unknown extrahost environment, so far supported by anecdotal evidence [12–15]. We have recently described a search of the National Center for Biotechnology Information (NCBI) nucleotide database that revealed evidence of Bordetella species in a large number of soil and water samples [15]. Phylogenetic analyses suggested that Bordetella species from these environments are the ancestral source from which modern respiratory pathogens emerged. To be successful in these environments, bordetellae are expected to be well adapted to interact with other bacteria and environmental predators. Thus, we hypothesize that Bordetella species have evolved mechanisms to successfully interact with predators and that these are associated with the Bvg - phase.

Amoebae are common environmental protists that feed on bacteria and have been isolated from soil, air, water, and nasal mucosa of both healthy and sick human volunteers [16–18]. When food (e.g., bacteria) is plentiful, amoebae survive and proliferate as single-celled amoebae. However, once the food source has been depleted from an area, some species of amoebae cooperate to spread to new, more fertile hunting grounds. In the case of D. discoideum, this cooperation involves a cyclic adenosine monophosphate (cAMP) signal that triggers aggregation of amoebae to ultimately form a multicellular fruiting body comprising a stalk and a sorus containing amoeba spores [19]. Sori can be disseminated in various ways, such as by wind shifting leaf litter or by the shuffling of passing animals, allowing the spores a chance to be deposited onto new food sources where they can germinate and once again feed as single-celled organisms. While many species of bacteria serve as a food source for amoebae, some bacteria, including several human pathogens such as Legionellae pneumophila and Francisella tularensis [20], have evolved means of surviving amoeba predation by persisting in single amoeba cells and blocking their host’s ability to differentiate into mature fruiting bodies [21–23]. Since amoebae and immune cells share similarities in their mechanisms used to phagocytize and kill bacteria [24], the ability of these pathogens to survive intracellularly during in vivo infection may be linked to an evolved mechanism for avoiding amoeba predation. Moreover, the relatively frequent isolation of amoebae from healthy human nasal mucosa [25] indicates that persistent nasal colonizers such as Bordetella spp. frequently encounter amoebae in vivo, raising the possibility that complex interactions between these organisms may have evolved over time.

We have previously shown that B. bronchiseptica can occupy an intracellular niche within macrophages during infection [3], an ability shared with other organisms that survive amoeba predation. Here, we show that B. bronchiseptica not only survives amoebic predation but also successfully infects and persists within amoeba cells. Unlike other bacteria that block fruiting body development [21–23], we show that B. bronchiseptica permits the complete D. discoideum life cycle and even localizes to the sori of the amoeba fruiting bodies for further propagation. Importantly, B. bronchiseptica is sequentially carried along with amoebic spores to new locations through many passages on other bacterial “food,” providing sustainable expansion/dissemination during a viable life cycle outside of a mammalian host. We show that the Bvg - phase is advantageous for B. bronchiseptica survival in the amoeba sori and therefore identify a role for the Bvg - phase in this potential ex vivo life cycle. When associated with the amoeba sori, B. bronchiseptica can be transferred by flies or ants and can efficiently infect mice, suggesting that amoebae can act as amplifying and transmission vectors for B. bronchiseptica in addition to being environmental reservoirs. Together, these data suggest a role for the Bvg - phase in a life cycle that does not require a mammalian host, which may explain the complexity and high conservation of genes specifically expressed in the Bvg - phase.

The Science Of Disinfectants

We often take for granted the action of disinfectants without fully understanding how they work. Not only are there differences in the action of the antimicrobial ingredients, but there are also differences depending on the concentration of chemical that is used that can impact the action of a chemical agent or physical process. In general, disinfectants have three mechanisms of action or ways that they affect or kill an organism: Cross-linking, coagulating, clumping structure and function disruption and oxidizing.

Mechanism of action: Cross-linking, coagulating, clumping.

Like many disinfectants, alcohols are generally considered to be non-specific antimicrobials because of their many toxic effects. Alcohols cause cell proteins to clump and lose their function. Specifically, the cell membranes lose their structure and collapse, thereby killing it.The alcohol must be diluted with water for the optimum effect, as proteins are not denatured as readily with straight alcohol.

Alcohol is also effective in inhibiting spore germination by affecting the enzymes necessary for germination. However, once it’s removed, spores can recover, so it’s not considered a sporicidal.

Mechanism of action: Oxidizing.

Chlorine is a very common disinfectant used in a wide variety of cleaning solutions and applications &mdash even in drinking water &mdash because, even in very small amounts, it exhibits fast bactericidal action. Chlorine works by oxidizing proteins, lipids and carbohydrates. Hypochlorous acid, which is a weak acid that forms when chlorine is dissolved in water, has the most effect on the bacterial cell, targeting some key metabolic enzymes and destroying the organism. Chlorine compounds have also been shown to affect surface antigen in enveloped viruses and deoxyribonucleic acid (DNA) as well as structural alterations in non-enveloped viruses.

Very few chemicals are considered sporicidal however, chlorine compounds in higher concentrations have been shown to kill bacterial spores such as Clostridium difficile (C. diff).

Peroxygen Compounds

Mechanism of action: Oxidizing.

Both hydrogen peroxide and peracetic acid are peroxygen compounds of great importance in infection control because, unlike like most disinfectants, they are unaffected by the addition of organic matter and salts. In addition, the formation of the hydroxyl radical, a highly reactive ion that occurs as peroxygen compounds encounter air, is lethal to many species of bacteria because it is a strong oxidant. Being highly reactive, the hydroxyl radical attacks essential cell components and cell membranes, causing them to collapse.

Peroxygen compounds also kill spores by removing proteins from the spore coat, exposing its core to the lethal disinfectant.

Mechanism of action: Cross-linking, coagulating, clumping.

Phenol and its derivatives exhibit several types of bactericidal action. At higher concentrations, the compounds penetrate and disrupt the cell wall and make the cell proteins fall out of suspension. One of the first things to occur is stopping essential enzymes. The next level in the damage to the bacteria is the loss in the membrane’s ability to act as a barrier to physical or chemical attack.

Though phenols can act at the germination &mdash beginning of growth &mdash stage of bacterial spore development, this effect is reversible, making them unsuitable as sporicides.

Quaternary Ammonium Compounds

Quaternary ammonium compounds (quats) are some of the most widely used disinfectants today because of their broad spectrum effectiveness. Quaternary ammonium compounds work by denaturing the proteins of the bacterial or fungal cell, affecting the metabolic reactions of the cell and causing vital substances to leak out of the cell, causing death. Because quats are a charged particle, something to consider is “quat absorption,” which is when quat molecules are attracted and bound to anionic &mdash negatively charged &mdash fabric surfaces. For example, if a pail contains the correct dilution of a disinfectant with an active ingredient concentration of 800 parts per million (PPM), that concentration could be reduced by as much as half after a cotton wipe is placed in the solution and allowed to soak for 10 minutes. Some ways to solve quat absorption include using wipes made from nonreactive textiles and increasing the solution concentration to compensate for absorption.

The Right Stuff

While each of the chemicals described above are effective in certain applications, formulations are also made more or less effective by their other ingredients. In particular, surfactants are often important ingredients to disinfectant cleaning solutions because they achieve uniform wetting of surfaces and frequently help with cleaning.

Something to consider is that some surfactants contain positively-charged ions, which can inactivate negatively-charged antimicrobials like quaternary ammonium compounds by binding with them, making them less effective against a microbe. In contrast, low surfactant concentrations may improve the microbiocidal effect. The reason for the improved action is thought to be an accumulation of the agent within micelles of the surfactant, which absorb to the microorganism’s cell wall. The active substance thus becomes enriched at the cell wall, which means that a lower dose is required for the desired effect.

While chemistry is important, even the best formulations will not be effective if applied incorrectly or inconsistently. Other processes and interventions must also be in place to ensure that all areas are cleaned thoroughly each time. Understanding how different chemistries work can help you evaluate which ones are best suited to your facilities’ needs.

Chemical resistance

Spores are extremely resistant to a variety of chemicals, including acids, bases, oxidizing agents, alkylating agents, aldehydes and organic solvents. As a consequence, spores are often the most resistant organisms that chemical decontaminants are designed to deal with – thankfully, spores are killed by some chemical treatments. In a few cases (e.g. formaldehyde, nitrous acid, alkylating agents) the mechanism of spore killing is via DNA damage, as the survivors accumulate mutations and a recA mutation sensitizes spores to these agents ( Setlow et al. 1998 Loshon et al. 1999 Tennen et al. 2000 ) (Table 2). However, this is only true for a few genotoxic chemicals, and even oxidizing agents such as hydrogen peroxide that mutagenize growing cells do not do so to spores (Table 2). Indeed, most oxidizing agents appear to kill spores by causing some type of damage to spores’ external layers, principally the spore's inner membrane, such that when the treated spores germinate this damaged membrane ruptures resulting in spore death ( Loshon et al. 2001 Genest et al. 2002 Melly et al. 2002a Young and Setlow 2003, 2004a,b Shapiro et al. 2004 ). Mildly lethal treatment of spores with a variety of oxidizing agents also sensitizes the survivors to a subsequent treatment (e.g. wet heat) to which an undamaged inner membrane may be required for full spore resistance ( Cortezzo et al. 2004 ). However, the precise nature of the inner membrane damage caused by oxidizing agents is not known, although it is not the oxidation of unsaturated fatty acids.

For some chemical agents including larger aldehydes such as glutaraldehyde and ortho-phthalaldehyde, the mechanism of spore killing remains unclear, although these latter two chemicals do not kill spores by DNA damage ( Tennen et al. 2000 Cabrera-Martinez et al. 2002 ). Strong acid treatment appears to kill spores by causing them to ‘pop’ open, likely by rupturing the spore's inner membrane permeability barrier in some fashion ( Setlow et al. 2002 ). This may also be the mechanism for spore killing by organic solvents at elevated temperature. At least one treatment (strong alkali) thought to cause spore killing may not kill spores, as apparently alkali-killed spores can often be revived by appropriate treatment with lysozyme ( Setlow et al. 2002 ). Alkali appears to inactivate the lytic enzymes needed for spore cortex hydrolysis in spore germination, as these enzymes are located in the spore's outer layers where they are presumably more sensitive to alkali than are components located further within the spore.

In addition to different mechanisms of spore killing by different chemicals, there are also a number of mechanisms involved in spore resistance to different chemicals. The spore coat is of major importance in resistance to a large number of chemicals, in particular most oxidizing agents including chlorine dioxide, hypochlorite, ozone and peroxynitrite ( Setlow 2000 Genest et al. 2002 Melly et al. 2002a Young and Setlow 2003, 2004a,b ), although the coat has only a minor role in spore resistance to hydrogen peroxide ( Riesenman and Nicholson 2000 ). No specific coat protein has been associated with spore resistance to these chemicals and the coat may be serving only as ‘reactive armor’, detoxifying these chemicals before they penetrate to more sensitive components further within the spore. At least one enzyme, superoxide dismutase, which might detoxify a potentially damaging chemical has been found associated with the exosporium and/or coat of spores of some species ( Henriques et al. 1998 Lai et al. 2003 Redmond et al. 2004 ). However, it has not been demonstrated that this enzyme plays a role in spore resistance. Unlike the situation in growing cells where protoplast enzymes such as catalase, alkylhydroperoxidase reductase and superoxide dismutase play a major role in cell resistance by inactivating toxic agents, such enzymes play no role in dormant spore resistance, although they are present in the spore core ( Casillas-Martinez and Setlow 1997 ).

A second important factor in spore chemical resistance is the spore's inner membrane, which exhibits extremely low permeability to small hydrophilic and hydrophobic molecules ( Gerhardt et al. 1972 ). Even a molecule as small as uncharged methylamine crosses this membrane extremely slowly with B. subtilis spores the t1/2 for maximum methylamine uptake into the spore core is approx. 2 h at 23°C and even water may cross the spore's inner membrane very slowly ( Setlow and Setlow 1980 Swerdlow et al. 1981 Westphal et al. 2003 Cortezzo et al. 2004 Cortezzo and Setlow 2005 ). An increase in the permeability of this membrane, whether achieved by sporulation at low temperatures or by mildly lethal treatment with any of a variety of oxidizing agents also leads to increased spore sensitivity to agents that kill spores by damaging spore DNA and thus must cross the spore's inner membrane ( Cortezzo and Setlow 2005 ). Unfortunately, while the low permeability of the spore's inner membrane is clearly an important factor in resistance to some chemicals, the reason for this membrane's low permeability is not known, although this seems likely to be related to the immobility of inner membrane lipids noted above.

The third factor important in spore resistance to some chemicals is the saturation of spore DNA with α/β-type SASP ( Nicholson et al. 2000 Setlow 2000 ). Thus wild-type spores are not killed by hydrogen peroxide via DNA damage, while αβ − spores are much more sensitive to this agent and are killed via DNA damage (Table 2). The α/β-type SASP also protect DNA in vitro against damage by hydrogen peroxide. For both formaldehyde and nitrous acid, even wild-type spores are killed via DNA damage, but αβ − spores are much more sensitive to these agents ( Loshon et al. 1999 Tennen et al. 2000 ) (Table 2). However, the α/β-type SASP do not protect spore DNA against all chemicals, as alkylating agents such as ethylmethanesulfonate kill wild-type and αβ − spores at the same rate, and the α/β-type SASP do not block DNA alkylation by this type of agent in vitro ( Setlow et al. 1998 ).

3 of the Best Treatments to Clean for Coccidia

Coccidia is hard to get rid of, those oocysts are super difficult to kill! The oocysts have a hard, resistant wall around them. These strong walls protect the oocysts from harsh environmental conditions prolonging their survival under non-favorable environmental conditions.

Oocysts survive many chemicals and even freezing, but they do not cope with desiccation and high temperatures. With that in mind, here are 3 ways to clean for coccidia including cleaning techniques and products.

1. Heat &ndash Steam Cleaning, Boiling Water and Dry Heat

Using heat to clean for coccidia is the most effective treatment there is and its eco friendly! Steam cleaning your bearded dragons house and accessories is a great option to control the coccidial infection and for regular cleaning going forward.

The steam wand needs to be moved very slowly and methodically around the enclosure walls, moving from top down. The wand will be in very close contact with the walls to get maximum temperature.

Bowls and small accessories can be immersed in boiling water. Leave the accessories in the water until it the water starts to cool.

The oven may also be useful for your bearded dragon&rsquos accessories. The heat and dry air of the oven is quite detrimental to the oocysts. Of course, anything that is intended for the oven needs to be able to cope with the heat and not cause a hazard to you.

It is possible to inactivate or kill coccidia oocysts at temperatures below -30°C (-22°F) or above 40°C (104°F) (Constable, n.d.). Cryptosporidia oocysts will become inactive when exposed to temperatures 45-60°C for 5-9 minutes (Cranfield et al, as cited in Pasmans et al, 2008). Some species will tolerate heat better than others and the duration the heat must be applied for is also variable. So to cover your bases it is better to work with boiling temperature from steam or boiling water.

Needless to say, boiling water reaches 100°C (212°F). To attain that temperature with steam cleaners, the wand will need to be almost in direct contact with the wall. You can test the temperature of the steam by waving the wand over a cooking thermometer.

2. Cleaning products to treat coccidia.

Cleaning products for coccidia are limited. Use a 10% solution of ammonium hydroxide and leave on the areas to be cleaned for at least 45 minutes. Note, when you clean for coccidia, don&rsquot use bleach. Bleach does not kill coccidia (Divers & Mader, 2005).

The protective wall of the oocysts makes them hard to kill with common disinfectants. However, the wall does have tiny pores required for oxygen which some chemicals can get through. Unfortunately, some of those chemicals are quite toxic and you don&rsquot want them in your home.

Ammonia hydroxide is one of the cleaning products that can penetrate the coccidia oocysts wall. Ammonia hydroxide is ammonia with water already added and will come in various concentrations. You may be familiar with cloudy ammonia which is ammonia with soap in it. You need ammonia hydroxide not cloudy ammonia.

Purchase ammonia hydroxide at concentration of 10% or higher. You can dilute higher concentrations to reach the desired 10% for cleaning.

Ammonia is in many household cleaning products it is alkaline, corrosive and quite suffocating. Regardless of its commonality in our world, take caution and read the manufacturer&rsquos instructions when using. Ammonia is irritating and if inhaled can cause burning of the throat and respiratory tract. It can also irritate the skin, eye and at extremes it can cause burns.

A study back in 1940 by Horton-Smith et al on ammonia concentrations for poultry farming showed that varying concentrations of ammonia and water killed coccidia oocysts over different durations. A 1% ammonia solution killed 100% of oocysts but it took 24 hours whereas a 10% solution only required 45 minutes. Although that was on the Eimeria strain, the strength of ammonia hydroxide solution is echoed by vets treating Isospora strain in reptiles anywhere between 5% (Divers & Mader, 2005) to 10%.

Ammonia hydroxide is an effective cleaning product against oocysts but not effective against most bacteria. To finish off the clean, after treating the coccidia and before you return everything to its place, use a disinfectant such as F10 and dry the surfaces.

3. UV &ndash Sunlight

Can sunlight kill coccidia oocysts? There are a number of studies showing various strains of coccidia will perish in direct sunlight but none specifically for Isospora amphiboluri.

A 100 years ago sunlight was recommended in controlling some strains of coccidia along with hot water and steam (Wilson, 1930). The effectiveness of sunlight killing Eimeria oocysts was also noted by the University of New Mexico Biology (Department of Biology at University of New Mexico, n.d.). In the case of Isospora oocysts Long (Long, 1982) also speaks of unsporulated oocysts being easily damaged if dried out and by direct sunlight.

So, to clean for coccidia use direct sunlight in the cleaning program. Drying accessories in the sun is a good and viable option. Use it as an additional strategy to control coccidia rather than an alternative on its own. There are two problems using it on its own:

  • there isn&rsquot any evidence to show us the effect on Isospora amphiboluri,
  • there are a number of variables such as surface exposure of items, duration of exposure and so on.

However, there is evidence that providing your bearded dragon with that direct sunlight will do wonders for its immune system so it would be good to take it outside as well.

Keep in mind that any accessories with crevices or surfaces that provide cover for oocysts will not be effectively treated by sunlight. Ensure nothing is in between the surfaces that oocysts may have resided on and the sun. No shade, no glass or other objects that may impede the transmission of UV.


With time, widespread bacterial antimicrobial resistance diminishes the clinical efficacy of antibiotics, threating the health of humans and animals [1,2]. There is serious concern about the rise of antibiotic-resistant “superbugs” now resistant to many antibiotics [3]. These include the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) [4]. The dramatic increase in antibiotic resistance makes infectious diseases a challenge for medicine worldwide. The total deaths from methicillin-resistant S. aureus (MRSA) are now comparable to those caused by HIV, and it is estimated that by the year 2050, at least 10 million people will die annually due to antimicrobial resistance [5]. The endless evolution and spread of antibiotic resistance and the emergence of new pathogens are driving the quest for novel drugs, now an urgent necessity [6].

Antimicrobial peptides (AMPs) are essential components of innate immunity in most organisms that fight against microbial challenges. Although some AMPs are templates for developing new antibiotics [7], progress is restricted by their toxicity and reduced half-lives in human body fluids. When secreted, small bacterial toxins can act as AMPs. Their toxicity to human cells can be reduced while retaining their antibiotic activity [8].

In the present study, we designed and synthesized 4 cyclic heptapseudopeptide biomimetics (Fig 1A and S1 Fig), inspired by and imitating a section of an S. aureus toxin, PepA1 [9]. PepA1 is a toxic linear peptide expressed from a type I toxin-antitoxin system the synthesis of which is repressed by an antisense RNA during bacterial growth. Herein, we designed novel pseudopeptides with activities against antibiotic-resistant gram-positive and -negative pathogens in infected mice, with limited potential of resistance emergence.

(A) Biomimetic design of antibiotics from a bacterial toxin [9]. Selected residues from the S. aureus toxin were cyclized, and unnatural amino acids (Ψ) were incorporated to synthesize those new antibiotics. Data associated with this panel can be found in S1 Fig. (B) Kill curves of MRSA using Pep16 (red), Pep19 (green), and vancomycin (blue) at concentrations 30-fold above the MIC are compared to untreated bacteria (black). Means and standard errors of the means are representative of 3 independent biological replicates. Data associated with this panel can be found in S3 Fig. (C–D) Pep16 and Pep19 antibiotic activity against MRSA strain Mu3 (red) compared to their low toxicity on human erythrocytes (blue bars) or to human kidney cell viability (green). Pep16 and Pep19 concentration range is from 0.5 to 512 μM. Data associated with this panel can be found in S4 Fig and S2–S6 Tables. (E) Overview of the mouse sepsis experiment. (F–G) Kaplan-Meier survival probability plots of mice infected with either MRSA without treatment (black), or with 1.5 −1 Pep19 (green) or vancomycin (blue). In a sepsis protection model, groups of 5 Swiss mice were inoculated with approximately 5 × 10 8 MRSA and treated either 3 h (F) or 15 h (G) post infection. Survival was monitored for 14 days after infection (panel d x-axis), and the results are from 10 mice. The experiment was performed twice and the data combined. Data associated with these two panels can be found in S3 Fig. (H–J) Kaplan-Meier survival probability plots of severe sepsis assays (nearly all untreated infected mice killed within 2 days post infection) with mice infected with approximately 2.10 9 CFUs MRSA either without treatment (black) or with 4 repeated doses (0.5 −1 ) of Pep16 (red), Pep19 (green), vancomycin (blue), or brilacidin (purple). The results are from 5 mice per assay, and the experiment was performed twice. Mice monitoring was performed for 5 days. (K) Overview of the mouse skin infection experiments with either S. aureus or P. aeruginosa. (L) Treatment of cutaneous abscesses from MRSA in mice using Pep16, Pep19, or vancomycin. Mice were infected with approximately 2 × 10 9 MRSA and treated by IV 24 h post infection with a saline solution (black) or with 1.5 −1 of Pep16 (red) or Pep19 (green) or vancomycin (blue). Lesion sizes and the CFU counts per abscess, plotted as individual points, were determined 6 days post infection (10 mice per condition). The abscess photos below the graph correspond to each experimental value shown in the graph as empty symbols. Intracellular ATP levels from S. aureus in the “normal-growing” (empty histograms) versus SCVs (filled colored histograms) collected from the mice skin abscesses (lower panels). (M) Treatment of cutaneous abscesses induced by P. aeruginosa in mice using Pep16, Pep19, or colistin. Mice were infected with approximately 108 P. aeruginosa and treated with repeated doses post infection with a saline solution (black) or with Pep16 (red, 30 −1 ), Pep19 (green, 30 −1 ), or colistin (orange, 9 −1 , lower panel). The CFU counts per abscess, plotted as individual points, were determined 3 days post infection (5 to 8 mice per condition). The abscess photos below the graph correspond to each experimental value shown as empty symbols. Mann-Whitney was used to calculate the differences between the groups *0.05 < P < 0.01 **0.01 < P < 0.001 ***0.001 < P < 0.0001 ****P < 0.00001. Data associated with this figure can be found in S1 Data. CFU, colony-forming unit Ctrl, controls MDR, multidrug resistant MIC, minimal inhibitory concentration MRSA, methicillin-resistant S. aureus OD600, optical density at 600 nm SCV, small colony variant.

How does glutaraldehyde kill bacteria? - Biology

CONTROL OF MICROORGANISMS Readings in Tortora et. al.: Chapter 7, Chapter 8 - mutation, especially that due to radiation, Chapter 20. Be familiar with the terms in chapter 7. Controling microorganisms can either be positive or negative:

POSITIVE control - you want to make them grow: Industrial Fermentations beer, wine and bread making

NEGATIVE control - you want to destroy them by (1) physical or chemical means or (2) antibiotics

Usually we mean negative control and the rest of this discussion relates to the destruction or inhibition of microbes:

PHYSICAL AND CHEMICAL METHODS - see Tortora et. al. for terms.

Small Non-enveloped viruses (polio, rotavirus, rabies)

Enveloped Viruses (Herpes, Hepatitis B, Hepatitis C, HIV)

Most Sensitive to destruction (least resistant to physical and chemical agents)

HEAT - Denatures proteins Moist heat is more effective than Dry heat.

FILTRATION - See the discussion and figure in Tortora et. al. on this. Membrane filters (Millipore TM ) are used to sterilize heat sensitive liquids. HEPA filters are used to sterilize air in biohazard hoods.

ULTRASONIC CLEANERS - Good for removing organic contaminants - "presterilize." Not bacteriocidal.

Ultraviolet Light (See Tortora, for a description of what UV light does to cells).

UVB = 280-320 nm UVA = 320-400 nm

Germicidal lamps are used to disinfect air and surfaces. UV does not penetrate glass, plastic or water very well.

UV light does harm eyes and skin.

Ionizing Radiation = X-Rays and Gamma Rays - sporocidal and penetrate well.

CHEMICALS - many of these are called antiseptics or disinfectants or both.

Sterilizing Chemicals: Ethylene Oxide


Phenol (spores may withstand)

Halogens (iodine, chlorine, bromine)



HALOGENS CHLORINE - Excellent disinfectant, sporocidal, however easily inactivated by organic material. Dilutions of household bleach between 1:10 - 1:100 are sporocidal after 10 minutes of treatment. 2-4 drops of bleach per liter of water can be used to treat drinking water (let stand 30 min.)

IODINE-Similar to chlorine. Often found as a tincture or alcohol solution. Also found as an iodophor (betadine TM )where the iodine is complexed with an organic molecule. Iodophors are more stable than tinctures and they release iodine more slowly and steadily. Therefore they are less harmful to human tissue.

HYDROGEN PEROXIDE - This is a strong oxidizing agent which is very effective against vegetative bacteria on inanimate surfaces. The catalase in human tissue neutralizes H 2 O 2 however the generation of oxygen bubbles helps to clean out wounds and is strongly inhibitory to anaerobic bacteria.

Chemical Compounds Commonly Used as Antiseptics and Disinfectants
Compound Type of Action Applications
Hydrogen peroxide (3%) Disinfectant/antiseptic External surfaces, live tissue
Hypochlorites (0.5%) (Chlorox) Disinfectant External surfaces, non-living
Iodine (1% in 70% alcohol) Disinfectant/antiseptic External surfaces, live tissue
Iodophors (70 ppm available I2) Disinfectant/antiseptic External surfaces, live tissue, surgical scrub
Lysol (5%) Disinfectant External surfaces, non-living
Phenol (5%) Disinfectant External surfaces, non-living
Hexachlorophene (pHisohex) Disinfectant/antiseptic External surfaces, live tissue surgical scrub
Formaldehyde (4%) Disinfectant External surfaces, non-living
Zephrin and other quaternary ammonium compounds Disinfectant Exernal surfaces, non-living
Alcohol (ethyl or isopropyl at 70%) Disinfectant/antiseptic External surfaces, unbroken skin
Organic mercury (merthiolate, mercurochrome) Disinfectant/antiseptic External surfaces
Potassium permanganate Antiseptic superficial skin fungus infections
Silver nitrate (1%) Antiseptic prevent newborn eye infections
Ethylene oxide gas (12%) Sterilizing disinfectant Linens, heat labile plastics
Glutaraldehyde Sterilizing disinfectant metal instrument sterilization
Formaldehyde (20% in alcohol) Sterilizing disinfectant metal instrument sterilization


Most are derived from compounds which are biosynthesized by other microorganisms. Streptomyces and Penicillium are two organisms which have given us antibiotics. The famous immunologist Paul Ehrlich devoted much of his career looking for the "Magic Bullet" or the chemical compound with SELECTIVE TOXICITY. That is, such a compound would be toxic for the infecting microbe but not for the human host. This dream was achieved by Flemming and Florey with the discovery and mass production of penicillin.

Antibiotics achieve selective toxicity by exploiting the differences between eucaryotes and procaryotes. The most profound differences are at the cell wall and at the ribosome level. It follows then that most of our antibiotics either inhibit bacterial cell wall synthesis or inhibit the synthesis of bacterial proteins. For instance: ampicillin and penicillin interfere with cell wall synthesis chloramphenicol, gentamicin, streptomycin and tetracycline interfere with protein synthesis. How does triple sulfa work?

Antibiotic resistance is a growing problem which has at its source the indiscriminate and inappropriate use of antibiotics. Some of the current "Super Bugs" include methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococcus (VRE) and multidrug resistant Mycobacterium tuberculosis. It is important that physicians order sensitivities on bacteria isolated from infection sites so that appropriate antibiotics can be prescribed. Also, it is important that the infection be hit hard with high, optimum doses of the antibiotic and that tissue levels of the antibiotic remain high throughout therapy. Therapy must continue until all of the pathogens are dead - this means that the patient must continue to take the antibiotic even after the symptoms are gone.

Watch the video: Βακτήρια στα χέρια (May 2022).