Gram Positive Bacteria

This electron micrograph depicted large numbers of Staphylococcus aureus bacteria, which were fond on the luminal surface of an indwelling catheter. Of importance is the sticky-looking substance woven between the round cocci bacteria, which was composed of polysaccharides, and is known as biofilm. This biofilm has been found to protect the bacteria that secrete the substance from attacks by antimicrobial agents such as antibiotics; Magnified 2363x.S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

Scanning Electron Micrograph of Streptococcus pneumoniae.Created:

This highly magnified electron micrograph depicted numbers of Staphylococcus aureus bacteria, which were fond on the luminal surface of an indwelling catheter. Of importance is the sticky-looking substance woven between the round cocci bacteria, which was composed of polysaccharides, and is known as biofilm. This biofilm has been found to protect the bacteria that secrete the substance from attacks by antimicrobial agents such as antibiotics; Magnified 2363x.S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

Scanning Electron Micrograph of Streptococcus pneumoniae.Created:

This highly magnified electron micrograph depicted numbers of Staphylococcus aureus bacteria, which were fond on the luminal surface of an indwelling catheter. Of importance is the sticky-looking substance woven between the round cocci bacteria, which was composed of polysaccharides, and is known as biofilm. This biofilm has been found to protect the bacteria that secrete the substance from attacks by antimicrobial agents such as antibiotics; Magnified 2363x.S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

Scanning Electron Micrograph of Streptococcus pneumoniae.Created:

This highly magnified electron micrograph depicted numbers of Staphylococcus aureus bacteria, which were fond on the luminal surface of an indwelling catheter. Of importance is the sticky-looking substance woven between the round cocci bacteria, which was composed of polysaccharides, and is known as biofilm. This biofilm has been found to protect the bacteria that secrete the substance from attacks by antimicrobial agents such as antibiotics; Magnified 2363x.S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

This 1977 photograph depicted two Petri dishes each filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP). The plate on the left had been stabbed and streaked with an inoculum containing Streptococcus mitis, alpha-hemolytic bacteria, a member of the Viridans group, while the right plate was stabbed with an inoculum containing Group A Streptococcus pyogenes (GAS), a typical beta-hemolytic bacteria. The inoculation was performed using a wire loop, which had been dipped into a primary culture medium. The BAPs were incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. There is no magnification of this image.Created: 1977

This electron micrograph depicted large numbers of Staphylococcus aureus bacteria, which were fond on the luminal surface of an indwelling catheter. Of importance is the sticky-looking substance woven between the round cocci bacteria, which was composed of polysaccharides, and is known as biofilm. This biofilm has been found to protect the bacteria that secrete the substance from attacks by antimicrobial agents such as antibiotics; Magnified 2363x.S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

Under only a 2X magnification, this photograph revealed some of the details displayed atop a Petri dish culture of rod-shaped, Gram-positive Clostridium septicum bacteria.Created: 1971

This electron micrograph depicted the biofilm formation found inside the lumen of an indwelling catheter being secreted by Staphylococcus aureus bacteria. The biofilm secretions are primarily composed of polysaccharides, and by covering the bacteria, render the bacteria resistant to attacks they may face from antimicrobial agents. S. aureus, often referred to simply as "staph," are bacteria commonly carried on the skin, or in the nose of healthy people. Approximately 25% to 30% of the population is colonized, i.e., when bacteria are present, but not causing an infection, in the nose with staph bacteria.Created: 2005

Under only a 2X magnification, this photograph revealed some of the details displayed atop a Petri dish culture of rod-shaped, Gram-positive Clostridium septicum bacteria.Created: 1971

This is a scanning electron micrograph depicting Gram-positive Staphylococcus aureus bacteria.Created: 2003

Under only a 2X magnification, this photograph revealed some of the details displayed atop a Petri dish culture of rod-shaped, Gram-positive Clostridium septicum bacteria.Created: 1971

This methylene blue-stained micrograph shows Staphylococcus aureus bacteria, an organism linked to Toxic Shock Syndrome.Created: 1984

Under only a 2X magnification, this photograph revealed some of the details displayed atop a Petri dish culture of rod-shaped, Gram-positive Clostridium septicum bacteria.Created: 1971

Magnified 20,000X, this scanning electron micrograph depicts a grouping of methicillin resistant Staphylococcus aureus (MRSA) bacteria. See PHIL 9994 for a colorized version of this image.Created: 1998

Scanning Electron Micrograph of Enterococcus faecalisCreated:

Magnified 100x, this 1977 photograph depicted a Petri dish filled with heart infusion agar medium containing 5% defibrinated rabbit blood, i.e., blood agar plate (BAP). After having been inoculated, using the "stab" technique using a culture of Streptococcus anginosus bacteria, of the Gram-positive viridans group of streptococci (VGS), the BAP was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. The culture grew bacterial colonies around the stab site, surrounded by what is known as "wide zone alpha hemolytic" (WZα) color changes. Characteristics of WZα reactivity are described as, "the area immediately adjacent to the colony has some red blood cells (RBCs), but an area outside of that may be completely, or nearly completely, cleared of RBCs. Therefore, there are no reactive zones where "complete" RBC hemolysis has occurred, as in the case in beta-hemolytic reactions, hence the Wide Zone "alpha" terminology.Created: 1977

This photograph depicted a colony of a Streptococcus salivarius growing in the Petri dish filled with trypticase soy agar with 5% sheep's blood, (BAP). A loop of diluted culture of S. salivarius was put into the melted agar (50oC) just before the blood was added. The melted agar with blood was allowed to solidify, and then incubated at 35oC for 24 hours in a normal atmosphere. The culture grew subsurface bacterial colonies, one of which is seen here. There were no color changes in the region surrounding the colony, indicating that the red blood cells in the blood agar medium have not been altered in any way, which meant that these bacteria were indeed non-hemolytic in nature.Created: 1977

Magnified 100x, this 1977 photograph depicted a Petri dish filled with heart infusion agar medium containing 5% defibrinated rabbit blood, i.e., blood agar plate (BAP). A loop of diluted culture of Streptococcus anginosus was put into the melted agar (50oC) just before the blood was added to the melted agar. The agar was allowed to solidify, and then incubated at 35oC for 24 hours in a normal atmosphere. The culture grew subsurface bacterial colonies, one of which is seen here, surrounded by what is known as "wide zone alpha hemolytic" (WZα) color changes. Characteristics of WZα reactivity are described as, "the area immediately adjacent to the colony has some red blood cells (RBCs), but an area outside of that may be completely, or nearly completely, cleared of RBCs. Therefore, there are no reactive zones where "complete" RBC hemolysis has occurred, as in the case in beta-hemolytic reactions, hence the Wide Zone "alpha" terminology.Created: 1977

Magnified 100X, this image depicted a Petri dish filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP). After having been inoculated by stabbing the surface of the BAP with a non-hemolytic group A Streptococcus pyogenes (GAS) bacteria. The BAP was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. The culture grew bacterial colonies along the stab in the BAP. There are no clear characteristic color changes in the region surrounding the stabbed area of the BAP in which the red blood cells in the blood agar medium have been altered to some extent. This "hemolyzed zone" indicated that these bacteria appear more like alpha- or WZ-alpha colonies in nature, which means that stabbing the BAP with non-hemolytic GAS is not helpful in the identification of the non-hemolytic variants of GAS.Created: 1977

Magnified 100x, this 1977 photograph depicted a Petri dish filled with heart infusion agar medium containing 5% defibrinated rabbit blood, i.e., blood agar plate (BAP). After having been inoculated with a culture of Streptococcus anginosus bacteria, of the Gram-positive viridans group of streptococci (VGS), the BAP was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. In this view, one can see numbers of growing "surface" colonies surrounded by what is known as "wide zone alpha hemolytic" (WZα) color changes. Characteristics of WZα reactivity are described as, "the area immediately adjacent to the colony has some red blood cells (RBCs), but an area outside of that may be completely, or nearly completely, cleared of RBCs. Therefore, there is no reactive zones where "complete" RBC hemolysis has occurred, as is the case in beta-hemolytic reactions, hence the Wide Zone "alpha" terminology.Created: 1977

This photograph depicted a subsurface bacterial colony of a non-hemolytic S. pyogenes growing in a Petri dish filled with trypticase soy agar with 5% sheep’s blood, (BAP). A loop of diluted non-hemolytic S. pyogenes culture was put into the melted agar (50oC) just before the blood was added to the melted agar, which was then allowed to solidify. It was then incubated at 35oC for 24 hours in a normal atmosphere. There was only a very small color change in the region surrounding the colony indicating that a narrow zone of red blood cells in the medium had been altered, which meant that these bacteria were "narrow-zone"-hemolytic in nature. Among the streptococcal species this hemolytic activity is found only with "non-hemolytic GAS".Created: 1977