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Gram Positive Bacteria: Introduction, Characteristics, Benefits

Gram-positive bacteria are members of the phylum Firmicutes and the genus of the bacterium family. Check this article to know more about Gram Positive Bacteria.
authorImageJasdeep Bhatia21 Jun, 2024
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Gram Positive Bacteria

If you are looking for “Gram-Positive Bacteria”, you have come to the right place!

In this article, gram-positive bacteria will be covered. Gram-positive bacteria respond favorably to the Gram stain test in bacteriology. This test is widely used to divide bacteria into two categories based on their type of cell wall. Gram-positive bacteria are visible as purple under an optical microscope due to thei absorption of the crystal violet dye used in the test.

Gram Positive Bacteria

The genus of the bacteria family and a part of the phylum Firmicutes are known as gram-positive bacteria. These microorganisms maintain the colour of the gram-stained crystal violet stain. Gram-positive bacteria exhibit a purple color under a microscope and produce a positive result in the Gram stain test. Some examples of Gram-positive bacteria are Actinomyces, Clostridium, Mycobacterium, Streptococci, Staphylococci, and Nocardia.

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Characteristics of Gram-Positive Bacteria

These bacteria have unique traits that set them apart from other types of bacteria. They are made up of the:
  • Their outer membrane is absent.
  • They contain a very thin coating of the cytoplasmic lipid layer.
  • They have a thick peptidoglycan covering.
  • The peptidoglycan layer contains an enormous amount of teichoic acid and a thin lipid layer composed of lipoteichoic acid and is essential for bacterial adherence.
  • The cell wall stiffness depends on the peptidoglycan layer, which DD-transpeptidase uses to cross-link.
  • They also have a thin covering of periplasm, just like Gram-negative bacteria.
  • Certain bacteria contain a locomotive device called a flagellum, which has two basal bodies for support, unlike gram-negative bacteria, which have four basal bodies.
  • Polysaccharides are employed in the robust capsules of some people.

Gonads

Classification of Gram-Positive Bacteria

Based on a variety of traits, gram-positive bacteria are further divided into the following groups:
  • Gram-positive cocci: Gram-positive cocci are shaped like an oval or circle. Cocci, which means sphere, suggests that germs are frequently spherical. Gram-positive cocci include any of the following:
    • Staphylococcus: This bacteria forms clusters that resemble bunches of grapes. They frequently persist without endangering the skin or mucous membranes. Staphylococci can, however, result in fatal infections if they enter the body.
    • Streptococcus: Staphylococci and streptococci are both often found in the body. They are frequently seen in the mouth, vagina, skin, and gastrointestinal tract.
  • Gram-positive bacilli: Gram-positive bacteria that form rod-shaped particles are referred to as bacilli. Even though most of these bacteria are often found on the skin, some can cause fatal infections.

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Pathogenicity

Staphylococcal species are responsible for the sharp rise in human skin and mucosal infection rates. The main modes of transmission for these bacteria are contact with animals, fomite contact, inhaling infected aerosolised particles, and skin contact. Other risk factors include diphtheria, mycobacterium tuberculosis, respiratory illnesses, tooth decay, and food poisoning.

Gram Stain

Gram stain examinations look for bacteria in regions suspected to be infectious, like the throat, lungs, genitalia, or skin wounds. Furthermore, gramme stains can be used to examine the presence of germs in bodily fluids like blood or urine. The two most common bacterial subtypes are Gram-positive and Gram-negative infections. How bacteria respond to the Gram stain allows us to identify many different types of bacteria. The colour of a Gram stain is purple. When the dye and bacteria interact, the bacteria in a sample stay purple or change to pink or red. They are Gram-positive bacteria if they continue to be purple. Bacteria that produce pink or crimson stains when exposed to light are known as gram-negative bacteria. The two groups cause the two types of ailments differently:
  • Methicillin-resistant Gram-positive infections include strep infections, toxic shock, and methicillin-resistant Staphylococcus aureus (MRSA).
  • Gram-negative infections include gonorrhoea, salmonella, pneumonia, and urinary tract infections.

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Risk of Gram-positive Bacteria

The cocci of Staphylococcus aureus are gram-positive, catalase-positive, and coagulase-positive. Skin infections, pneumonia, endocarditis, septic arthritis, osteomyelitis, and abscesses are inflammatory conditions brought on by S. aureus. Moreover, S. aureus can result in scalded skin syndrome (exfoliative toxin), toxic shock syndrome (TSST-1), and food poisoning (enterotoxin). Clusters of Staphylococcus epidermidis that are coagulase-negative, gram-positive, catalase-positive, and novobiocin-sensitive forms. Biofilms are typically created when S. epidermidis infects IV catheters and prosthetic devices. The novobiocin-resistant Staphylococcus saprophyticus is a prevalent member of the perineum and vaginal canal flora. The second most frequent cause of a straightforward urinary tract infection is S. saprophyticus.

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Benefits of Gram-Positive Bacteria

  • These non-pathogenic bacterial species are found throughout human bodies, including the mouth, skin, colon, and upper respiratory system.
  • These are necessary for making Swiss or Emmentaler cheese.
  • The Corynebacterium species are utilised to make many substances, including nucleotides, enzymes, and amino acids.
  • To secrete high amounts of enzymes, several Bacillus species are utilised.
  • A few gram-positive bacterial species are also engaged in other processes, such as the bioconversion of steroids, cheese ageing, the breakdown of hydrocarbons, etc.
  • The gram-positive bacterium Bacillus amyloliquefaciens is rich in the naturally occurring antibiotic protein.

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Gram-Positive Bacteria Examples and Diseases

The table below lists the many Gram-positive bacteria, their basic morphological traits, and the human diseases they cause.
Gram-Positive Bacteria Clinical Signs of Bacterial Infection
Staphylococcus aureus
  • They cause superficial and localised skin diseases like cellulitis, impetigo, wound infection, furuncles, and carbuncles.
  • Pneumonia and other respiratory illnesses.
  • cardiovascular illnesses, including septicemia and endocarditis.
  • Infections of the musculoskeletal system, such as osteomyelitis and arthritis.
Streptococcus pyogenes
  • Acute pharyngitis is often known as pharyngotonsillitis.
  • Impetigo
  • Erysipelas
  • Perinatal infection
  • Unwelcome group a streptococcal condition (myositis/necrotising fasciitis)
  • Strep toxic shock syndrome
  • Rheumatic fever, acute
  • Glomerulonephritis acute
Streptococcus pneumoniae
  • Community-acquired bacterial pneumonia is acute
  • bacterial meningitis in adults
  • Children's otitis media
  • Bacteremia/sepsis
  • Meningitis
Bacillus anthracis
  • It causes sepsis, which spreads to the digestive system and causes bowel ulcers and hemorrhagic meningitis, as well as pulmonary Anthrax disease (also known as Woolsorter's disease), hemorrhagic necrosis, and mediastinum oedema.
  • Oedema, pruritic papule lesions, lymphadenopathy, lymphangitis, and systemic symptoms like fever, malaise, and headache are all signs of anthrax illness in the dermal layer.
Corynebacterium diphtheria
  • Diphtheria is a respiratory infection that affects only the upper respiratory tract.
  • Congestive heart failure and irreversible heart damage could result from myocarditis and aberrant cardiac conduction if the illness invades the lower tract.
  • Together with cranial nerve neuritis, there is paralysis of the eye and leg muscles.
  • Cuts and wounds that are chronically ulcerated and non-healing from cutaneous diphtheria.
Clostridium botulinum
  • Bulbar paralysis, respiratory paralysis, and cardiac arrest can cause mortality from botulism poisoning. Other symptoms include trouble swallowing, speaking, and visual difficulties (double vision, uncoordinated eye muscles).
Clostridium tetani
  • Tetanus is characterised by tonic, voluntarily contracting muscles. Injuries bring on muscle spasms; an infection of the jaw muscles that makes it difficult to open the mouth.
  • Various tonic and tetanic broad muscular spasms can occur in the body.
Clostridium difficile
  • Pseudomembranous Colitis is accompanied by bloody, watery diarrhoea and intestinal microabscesses.
Enterococcus faecium and Enterococcus faecalis
  • They hardly ever infect healthy people. They can infect immune-compromised people and make them ill with wounds and accompanying equipment like respirators or catheters that can result in urinary tract infections, bacteremia/sepsis, endocarditis, biliary tract infections, or intra-abdominal abscesses.
Listeria monocytogenes
  • Meningitis and septicemia are linked to listeriosis.
  • Skin lesions that are focal and granulomatous
  • Newborns are exposed to an asymptomatic vaginal condition that can cause flu-like symptoms and meningitis.

Grazing Food Chain

Gram-Positive Bacteria Antibiotics

Many illnesses that are known to be brought on by gram-positive bacteria can have severe effects on individuals if they are not diagnosed, treated, and controlled promptly and efficiently. Antibiotics are chemotherapy treatments that work against the bacterial agent causing the illness and destroy it to eliminate it from the body. As a result, scientists created them. Antibiotics can be eliminated using a variety of techniques. Gram-Positive antimicrobial agents include
Antimicrobial agent Mechanism of action Examples of Bacteria
ß-lactamases: Amoxicillin, methicillin, Oxacillin, Ampicillin, and Penicillin G Destruction of the bacterial cell wall.
  1. Staphylococcus aureus
  2. Streptococcus pneumonia
  3. Streptococcus pyogenes
  4. Corynebacterium diphtheria
  5. Bacillus anthracis
  6. Clostridium botulinum
Vancomycin, Erythromycin, and Azithromycin Inhibits cell wall production by blocking the peptidoglycan peptidases from cross-linking.
  1. Staphylococcus spp
  2. Streptococcus spp
  3. Bacillus spp
  4. Clostridium difficile
Bacitracin By impeding the mobility of the cytoplasmic membrane and precursors of peptidoglycan, it inhibits the production of cell walls.
  1. Corneybacterium spp
  2. Bacillus anthracis
Macrolides: Azithromycin, Clarithromycin Limit the polypeptide elongation of 50s ribosomes, and inhibit the synthesis of bacterial proteins.
  1. Streptococcus pyogenes
Cephalosporin Inhibition of the production of cell walls (Disruption of peptidoglycan synthesis).
  1. Streptococcus pneumoniae
  2. Bacillus anthracis
Aminoglycosides: Gentamicin Formation of atypical peptide chains at the 30s ribosomes, inhibiting bacterial protein synthesis.
  1. Staphylococcus aureus
  2. Streptococcus pneumoniae
  3. Streptococcus pyogenes
  4. Enterococcus spp
Oxazolidinone Protein synthesis at ribosomes in the 50s is suppressed.
  1. Enterococcus spp
Rifampicin By obstructing binding DNA-dependent RNA polymerase from transcription suppresses the production of nucleic acids.
  1. Bacillus anthracis
Sulfonamides: sulfamethoxazole An antimetabolite that prevents the formation of folic acid by inhibiting dihydropteroate synthase.
  1. Listeria monocytogenes
Trimethoprim An antimetabolite that prevents the synthesis of folic acid by inhibiting dihydrofolate reductase.
  1. Listeria monocytogenes

Q1. What exactly do gram-positive and gram-negative mean?

Ans: A test to assess whether a bacterium had a thick, mesh-like membrane termed peptidoglycan was developed in 1884 by the bacteriologist Christian Gram. Gram-positive bacteria have thick peptidoglycan. 

Q2. Is it possible to treat gram-negative bacteria?

Ans: Multidrug-resistant microorganisms that cause infectious illnesses are a severe hazard to humankind. It has been proposed that an antibiotic that targets the lipid LpxC. A possible method for treating Gram-negative bacterial infections involves a metabolic pathway in those bacteria.

Q3. Are gram-positive bacteria toxic?

Ans: Several Gram-positive species can also inflict disease through the generation of toxins in addition to the classic sepsis syndromes. The clinical course of toxic shock syndrome (TSS), an acute, multi-system, toxin-mediated sickness, usually begins with shock and multi-organ failure.

Q4. Why are Gram-positive bacteria beneficial?

Ans: Many Gram-positive bacteria have highly adaptable secondary metabolisms that make them excellent biocontrol agents against insects, nematodes, fungi, and other bacteria. Additionally, many Gram-positive bacteria have extensive catabolic capacities that support their employment as bioremediation agents.
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