Differences between Fungi and Bacteria

Fungi and bacteria are two types of microorganisms that have distinct differences in their cellular structure and genetic makeup. Fungi are eukaryotic organisms, meaning they have a membrane-bound nucleus that contains their genetic material. On the other hand, bacteria are prokaryotic and lack a nucleus. Instead, they have a nucleoid, which is a collection of genetic material that is not membrane-bound.

Both fungi and bacteria have cell walls, but the composition of these walls differs. Fungal cell walls contain chitin, which is not present in bacterial or plant cell walls. Additionally, while both types of microorganisms have endoplasmic reticulum and ribosomes, the ribosomes in bacteria are smaller than those in eukaryotes.

Another difference between fungi and bacteria is the presence of plasmids. Bacteria have plasmids, which are circular rings of DNA that can be transmitted between organisms. Fungi, however, do not have plasmids.

In summary, while fungi and bacteria share some similarities in their cellular structure, they have distinct differences in their genetic makeup and composition of their cell walls.

Differences in Cell Wall Composition between Fungi and Bacteria

Fungi and bacteria both have cell walls, but the composition of their cell walls differs. While bacterial cell walls contain lipopolysaccharide in Gram negative bacteria and lipoteichoic acid in Gram positive bacteria, fungal cell walls contain chitin and glucans. These polysaccharides are not found in bacterial cell walls, which do not contain cellulose like plant cell walls do.

Peptidoglycan is a major structural component of Gram positive cell walls and a minor component of Gram negative cell walls. This compound is responsible for the ability of Gram positive cells to stain dark purple and Gram negative cells to stain pink. Peptidoglycan binds crystal violet, which is used in the Gram staining process. Overall, the differences in cell wall composition between fungi and bacteria contribute to their distinct characteristics and functions.

Cell Surface Projections

Flagella, fimbriae, and pili are all types of cell surface projections found in bacteria. Flagella are composed of flagellin and have a motor pump at the base that propels the filamentous structure to allow bacteria to move. This movement is important for bacteria such as Helicobacter pylori to penetrate through gastric mucus. Fimbriae and pili are short projections that aid in attachment. They can be used to attach to an epithelial layer, which increases virulence, or to attach to other bacteria, which facilitates the exchange of genetic material.

In contrast, microvilli are cell surface projections found on the apical surfaces of human epithelial cells, such as enterocytes. They increase the surface area for absorption, allowing for more efficient nutrient uptake. Overall, these cell surface projections play important roles in bacterial movement, attachment, and nutrient absorption in human cells.

Mechanisms of Antibiotic Action

Antibiotics work by targeting specific components of bacterial cells to inhibit their growth and replication. Penicillins, for example, target the bacterial cell wall by binding to penicillin-binding proteins, preventing cross-linking, and stimulating breakdown by activating autolytic enzymes. While penicillins have a relatively narrow range of coverage, they have been modified to give wider action, but the same mechanism of action is used by more advanced penicillins such as amoxicillin and piperacillin.

Other antibiotics target different components of bacterial cells. Rifampicin inhibits DNA synthesis, while trimethoprim inhibits folate production. Colistin inhibits membrane production, and chloramphenicol inhibits protein synthesis. Each antibiotic has a specific mechanism of action that makes it effective against certain types of bacteria.

the mechanisms of antibiotic action is important for developing new antibiotics and for using existing antibiotics effectively. By targeting specific components of bacterial cells, antibiotics can effectively kill or inhibit the growth of harmful bacteria, helping to prevent and treat infections.

The Role of Folate and Anti-Folate Antibiotics in DNA, RNA, and Protein Production

Folate, specifically in the form of tetrahydrofolate (THF), plays a crucial role as a co-factor in the production of DNA (thymine), RNA (purines), and proteins (methionine and glycine). However, certain antibiotics, such as sulphonamides like sulfamethoxazole, inhibit an early stage in the production of dihydrofolate. On the other hand, trimethoprim and pyrimethamine inhibit the conversion of dihydrofolate into tetrahydrofolate. When these two types of antibiotics are given together, as in the case of co-trimoxazole, they have a synergistic effect.

Another anti-folate antibiotic is dapsone, which is also used in the treatment of dermatitis herpetiformis. Overall, the balance between folate and anti-folate antibiotics is crucial for proper DNA, RNA, and protein production in the body.

Antibiotic-Associated Diarrhoea and Clostridium Difficile Infection

The majority of cases of antibiotic-associated diarrhoea are non-infective and are caused by changes in the normal gut flora. However, in certain patients, the use of broad-spectrum antibiotics can lead to the development of Clostridium difficile infection. This Gram-positive bacillus causes a colitis that results in profuse watery diarrhoea. In severe cases, the entire colonic mucosa is affected, leading to the formation of a pseudomembrane and severe dilatation of the colon, which can be life-threatening.

C. difficile is first-line treated with metronidazole, but if this is ineffective, oral vancomycin is used as a second-line treatment. Vancomycin is a glycopeptide antibiotic that has zero oral bioavailability, meaning that if it is given orally, none of it will enter the bloodstream. This makes it an ideal treatment for infections that are limited to the gastrointestinal tract, but it would not be useful for treating a systemic infection.

Hepatitis B Virus Transmission and Chronicity

Worldwide, the most common way of acquiring Hepatitis B virus (HBV) is through vertical transmission during the perinatal period. Infants who acquire the virus are usually asymptomatic, but 95% of them develop a chronic asymptomatic infection that does not clear spontaneously. This is because they enter a state of immune tolerance where the virus multiplies without immune-mediated hepatocyte death. However, between 20-50 years later, the immune system recognizes the virus, leading to a greatly raised ALT and potential clearance of the viral infection.

In contrast, adults who acquire HBV have a higher chance of developing symptomatic infection, with about 40-60% experiencing acute hepatitis and rarely liver failure. However, less than 5% of them will develop chronic infection, regardless of whether the acute infection was symptomatic or not. It is important to note that the degree of chronicity is unaffected by the patient’s age for the other hepatitis viruses. Hepatitis A and E always result in acute infections with no chronicity, while Hepatitis C is chronic only, with 90% of infected individuals developing chronicity. Lastly, Hepatitis D is only present if Hepatitis B is present. the transmission and chronicity of HBV is crucial in preventing its spread and managing its long-term effects.

Exanthema: Common Childhood Illnesses

An exanthema is a childhood illness that is characterized by a fever and a rash that blanches when pressure is applied. These illnesses are quite common in childhood and are usually mild and self-limiting. There are several types of exanthema, and some of them have been numbered for easy identification.

The first disease is measles, which is caused by a virus called paramyxoviridae. The second disease is scarlet fever, which is caused by a bacterium called Streptococcus pyogenes. The third disease is rubella, also known as German measles, which is caused by a virus called togaviridae. The fifth disease is erythema infectiosum, also known as slapped cheek disease, which is caused by a virus called parvoviridae. The sixth disease is roseola infantum, which is caused by two viruses called HHV6 and HHV7. The fourth disease is no longer recognized.

In addition to these numbered diseases, there are other viruses that can cause an exanthematous rash, including rhinovirus, mumps, and varicella zoster virus. Despite their prevalence, most exanthema illnesses are mild and do not require medical intervention.

Protozoan Infections of the Gastrointestinal Tract

Giardiasis is a gastrointestinal condition caused by the ingestion of water contaminated with cysts of the protozoan Giardia lamblia. This protozoan can exist in two forms, an inactive cyst form used for transmission and an active trophozoite form. Once ingested, Giardia invades the duodenal enterocytes and resides there, occasionally shedding cysts into the stool. The symptoms of giardiasis can mimic many other gastrointestinal conditions, including Coeliac disease, and may only be diagnosed by biopsy during endoscopy. Treatment for giardiasis involves the use of metronidazole.

Cryptosporidium is another protozoan that can cause gastrointestinal symptoms, but only in immunocompromised individuals. Entamoeba histolytica, on the other hand, causes colitis with bloody diarrhoea and can lead to liver abscesses if it invades through to the portal vein. Treatment for Entamoeba histolytica involves the use of metronidazole and iodoquinol to clear colonisation in the liver.

Schistosoma species are not protozoa, but rather helminths that cause schistosomiasis. This condition can manifest in various ways, including intestinal, liver, and pulmonary symptoms.

Systemic Inflammatory Response Syndrome

Systemic inflammatory response syndrome (SIRS) is a condition that is diagnosed when a combination of abnormal parameters are detected. These parameters can be deranged for various reasons, including both infective and non-infective causes. Some examples of infective causes include Staph. aureus toxic shock syndrome, while acute pancreatitis is an example of a non-infective cause. The diagnosis of SIRS is based on the presence of a constellation of abnormal parameters, which include a temperature below 36°C or above 38.3°C, a heart rate exceeding 90 beats per minute, a respiratory rate exceeding 20 breaths per minute, and a white blood cell count below 4 or above 12 ×109/L.

It is important to note that the systolic blood pressure is not included in the definition of SIRS. However, if the systolic pressure remains below 90 mmHg after a fluid bolus, this would be considered a result of septic shock. the criteria for SIRS is crucial for healthcare professionals to identify and manage patients with this condition promptly.