Gram-Negative Bacterial Infections

Introduction

Bacteria are microscopic organisms that consist of a single cell. They are the smallest and the earliest life forms found on the earth. There are thousands of bacteria on the planet, and they survive in different environments. Some are airborne, while others are found in soil, plants, water, animal, and even humans. They can be categorized into Gram-positive and Gram-negative bacteria. Infections caused by gram-negative bacteria are called Gram-negative infections.

What Are Bacteria?

These are small microscopic organisms. Many strains of bacteria do not cause any harm, and some are found to be beneficial, such as the bacteria present in the human gastrointestinal tract, which helps in the digestion of food and the production of certain vitamins. Very few bacteria (less than one percent) causes illness in humans. In contrast, some of them can cause serious illnesses such as pneumonia(an infection of the lungs), tuberculosis(TB), meningitis (inflammation of the meninges: the lining of the brain), etc.

Although bacterial infections are easy to track than viral infections since they do not replicate that rapidly. Several antimicrobial agents are effective against bacteria, but a new problem arising these days is bacterial resistance towards antimicrobials, whose consequences are devastating and challenging.

How Are Bacteria Classified?

They can be classified into several ways as-

• On the basis of staining- Gram-positive bacteria or Gram-negative bacteria based on the characteristic possessed by their cell wall, as seen under the microscope after staining by a method called Gram-staining. Most of the bacteria fall into either of these categories. The major difference between Gram-positive and Gram-negative bacteria is that Gram-negative bacteria produce endotoxin that causes tissue damage, shock, or may even result in death. While Gram-positive bacterias are comparatively less destructive.

• Need for Oxygen- Aerobic and Anaerobic Based on their need for oxygen for multiplication.

• Shapes- They can be categorized into different shapes such as spherical(cocci), rods(bacilli), spiral, or helixes(spirochetes).

What Are Bacterial Infections?

Bacterial infections are illnesses or any conditions caused due to various bacterial growths or toxins. These growths can occur inside any body part, including the lungs, stomach, heart, brain, bloodstream, skin, gut (gastrointestinal tract), or anywhere else.

These disease-causing bacterias enter the body through various routes, such as through contaminated objects(food, water, surfaces), the environment, or an infected person resulting in infection inside the body. The symptoms of bacterial infections include-

• Fever.

• Inflammation.

• Cogh.

• Headache.

• Chills.

• Shivering.

• Tiredness.

• Rapid breathing, etc.

What Are Gram-Negative Bacteria?

Gram-negative bacteria cause gram-negative bacterial infections. These are the group of aerobic bacteria that do not retain the crystal violet dye during the procedure of Gram-staining and appear pink in color when examined under the microscope. This is a method of staining developed to differentiate the two groups of bacteria (Gram-positive and Gram-negative) developed by Gram in 1884 by Sir Hans Christian Gram. These bacteria are enclosed in an outer layer called a capsule, due to which they are resistant to certain antibiotics like penicillin. When this outer layer gets disrupted, it releases a toxin called endotoxin, which is harmful and responsible for the symptoms' severity. There is a huge range of bacteria in the Gram-negative group, some of which are of medical importance, while some are too dangerous.

What Are Gram-Negative Bacterial Infections?

Gram-negative bacteria cause a variety of infections that are dangerous such as pneumonia(a type of infection of the lung), peritonitis(inflammation of the peritoneal cavity, lining of the heart), meningitis(inflammation of meninges, the outer layer of the brain), UTI (Urinary Tract Infections), bloodstream infections, wound or surgical site infections. Some other types of infections caused by Gram-negative bacteria are-

• Bruecillosis- It is caused by having contact with animals or due to the consumption of unpasteurized milk or uncooked meat. The symptoms include- fever, diarrhea, weight loss, constipation, etc. It can be treated with antibiotics such as doxycycline and streptomycin or gentamycin.

• Cholera- It is a serious small intestine infection caused by the Gram-negative bacteria, Vibrio cholera. This infection can be caused due to the consumption of contaminated water, food, shellfish, etc. The symptoms include diarrhea, vomit usually with no fever. The treatment includes purification of water and antibiotic intake such as doxycycline.

• Plague- It is caused due to Gram-negative bacteria Yersinia-pestis. It is spread mostly by rat-flea. The symptoms include headaches, swollen lymph nodes, fever, chills, etc. Its treatment is possible with antibiotics such as streptomycin and gentamycin.

• Salmonella- It is a common bacterial infection that affects the intestinal tract. The infection is spread by water and food mostly.

• Klebsiella infection- It affects the urinary or respiratory tract of people who are admitted to the hospital for a long time. Its treatment can be done by IV injection of antibiotics.

Gram-negative bacteria are becoming resistant to antimicrobial drugs, an issue of concern. It has created a threat because it is difficult to treat Gram-negative infections with high morbidity and mortality rates. For example, the resistance of E.coli to fluoroquinolones has vanished the use of such antibiotics, which has made it difficult to treat urinary tract infections. They can be resistant to antimicrobials because of any of the following reasons-

• They may be resistant naturally to certain antibiotics

• They develop resistance by acquiring genes from bacteria which has become resistant.

• Their genes mutate.

This resistance of Gram-negative bacteria has made it a major challenge in diagnosing, preventing, and treating infections caused by these drugs. To address such issues, proper comprehensive studies are required, and clinical trials need to be conducted so that the treatment of such harmful pathogens can be possible.

Conclusion

This article details bacteria and their types -Gram-positive and Gram-negative bacteria. Bacteria are a group of microscopic organisms that consists of a single cell and are the earliest and smallest known organism on earth. They can be classified into various types, one of which is Gram-negative bacteria responsible for Gram-negative infections such as pneumonia, meningitis, peritonitis, etc.

To fight against such infections, many antimicrobial agents are available. Some of these gram-negative infections are becoming a challenge to treat due to their resistance to antimicrobial agents, which is concerning because they show a high morbidity and mortality rate.