Basillit

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

Scanning Electron Micrograph of Enterococcus faecalisCreated:

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

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

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

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 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

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

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

Magnified 100X, this 1977 photograph 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 streaking 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, and grew bacterial surface colonies with no characteristic color changes surrounding each colony, or in the stabbed areas. Under examination, no red blood cells in the blood agar medium had been altered, or "hemolyzed", indicating that these bacteria were indeed non-hemolytic in nature.Infection with non-hemolytic GAS can result in a range of symptoms identical to that of typical beta-hemolytic GAS:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)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

This 1977 photograph (no magnification) depicted a Petri dish filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP) that had been inoculated by streaking and stabbing the surface of the BAP with a non-hemolytic group A Streptococcus pyogenes (GAS) bacteria. The BAP was then incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours, and grew bacterial surface colonies with no characteristic color changes surrounding each colony, or in the stabbed areas. Under examination, no red blood cells in the blood agar medium had been altered, or "hemolyzed", indicating that these bacteria were indeed non-hemolytic in nature.Infection with non-hemolytic GAS can result in a range of symptoms identical to that of typical beta-hemolytic GAS:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)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

Magnified 100x, this 1977 photograph 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 with Group A Streptococcus pyogenes (GAS) bacteria using a wire loop stab technique, the BAP was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. The culture grew bacterial colonies along the edge of the stab, a number of which were seen here. The characteristic color changes, i.e., a colorless region around the stabbed area containing colonies of GAS in which the red blood cells in the blood agar medium had been destroyed, or "hemolyzed", indicated that these bacteria were indeed beta-hemolytic in nature.Infection with GAS can result in a range of symptoms:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)Created: 1977

Magnified 10x, this image 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 both a streak and stab technique 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" and "stab" 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

Magnified 100x, this 1977 photograph depicted a Petri dish filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP). A loop of diluted culture of Streptococcus pyogenes was put into the melted agar (50oC) just before the blood was added to the melted agar. 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 was seen here. The characteristic color changes, i.e., a colorless region surrounding each colony in which the red blood cells in the blood agar medium had been destroyed, or "hemolyzed", indicated that these bacteria were indeed beta-hemolytic in nature.Infection with GAS can result in a range of symptoms:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)Created: 1977

This image 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 both a streak and stab technique with culture of Streptococcus anginosus bacteria, a member 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. In this view, one can see numbers of growing 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 had occurred, as is the case in beta-hemolytic reactions, hence the Wide Zone "alpha" terminology.Created: 1977

Magnified 100x, this 1977 photograph 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 streaking the surface of the BAP with Group A Streptococcus pyogenes (GAS) bacteria, the dish was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. The culture grew bacterial surface colonies. The characteristic color changes, i.e., a colorless region surrounding each colony in which the red blood cells in the blood agar medium had been destroyed, or "hemolyzed", indicated that these bacteria were indeed beta-hemolytic in nature.Infection with GAS can result in a range of symptoms:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)Created: 1977

Magnified 100x, this 1977 photograph 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, using a stab technique, with alpha-hemolytic Streptococcus anginosus bacteria, i.e., a member 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. In this view, one can see numbers of colonies that were growing at the edge of the stab, surrounded by the characteristic color changes, i.e., a hazy, faded, and indistinct region in which some of the red blood cells (RBCs) were destroyed in the blood agar medium, or "hemolyzed", indicating that these bacteria were indeed alpha-hemolytic in nature.Created: 1977

This 1977 photograph depicted a Petri dish with Streptococcus pyogenes-inoculated trypticase soy agar containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP), that had been "streaked", and "stabbed" with a wire loop, which had been dipped into primary culture medium. The BAP was incubated in a normal atmosphere at 35oC for 24 hours. In this case, the culture dish grew colonies of Gram-positive Group A beta-Streptococci (GAS) bacteria. The characteristic color changes, i.e., a clear, colorless region surrounding each colony in which the red blood cells in the blood agar medium had been destroyed, or "hemolyzed", indicated that these bacteria were indeed beta-hemolytic in nature. There is no magnification of this image.Infection with GAS can result in a range of symptoms:- No illness- Mild illness (strep throat or a skin infection such as impetigo)- Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)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 with alpha-hemolytic Streptococcus anginosus bacteria, i.e., members of the Gram-positive viridans group of streptococci (VGS), just before the blood was added to the agar, a loop of diluted culture was put into the melted agar (50oC). 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 was seen here. Surrounded by a characteristic hazy, faded, and indistinct region (arrow) in which some of the red blood cells were destroyed in the agar medium, or "hemolyzed", indicating that these bacteria were indeed alpha-hemolytic in nature.Created: 1977

This colorized version of PHIL 259, depicts a scanning electron micrograph (SEM) of two Staphylococcus epidermidis bacteria.Created:

Magnified 100x, this 1977 photograph 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 with alpha-hemolytic Streptococcus anginosus bacteria, i.e., a member 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, which were seen here. The characteristic color changes, i.e., a hazy, faded, indistinct region surrounding each colony in which some of the red blood cells (RBCs) were destroyed in the blood agar medium, or "hemolyzed", indicated that these bacteria were indeed alpha-hemolytic in nature.It is the incomplete nature of the hemolytic reaction adjacent to the colonies, which spares numbers of RBCs in the blood agar medium, that is of qualitative importance when distinguishing alpha from beta-hemolysisCreated: 1977

Scanning Electron Micrograph of Staphylococcus epidermidisCreated: