Gram Positive Bacteria

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). 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

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

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 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

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 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

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

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

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 with alpha-hemolytic Streptococcus anginosus bacteria, i.e., a member of the Gram-positive viridans group of streptococci (VGS), using a streak/stab technique, the BAP was incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. The culture grew bacterial colonies. Typical alpha-hemolytic colonies were seen adjacent to the stab sites (arrow). The hazy, faded, indistinct region surrounding each colony indicated that red blood cells (RBCs) were destroyed, or "hemolyzed", in the BAP, and 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-hemolysis.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

This 1977 image depicts 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 numbers of surface bacterial colonies. 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-hemolysis. No magnification was used here.Created: 1977

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

Scanning Electron Micrograph of Staphylococcus epidermidisCreated:

Magnified 1000X, this photomicrograph reveals numbers of Clostridium perfringens bacteria that had been grown in Schaedler’s broth, and subsequently stained using Gram-stain.Created: 1974

Scanning electron micrograph of a Staphylococcus biofilm on the inner surface of a needleless connector.Created: 2002