STAPHYLOCOCCUS AUREUS

 

Habitat:  Staphylococci are associated with skin, skin glands and mucous membranes of almost all the warm blooded animals.  When we talk about mucous membranes we are talking about the vestibule of the mouth, the vaginal canal, anal canal, the conjunctival sac of the eyes and the inner part of the nose. 

This bacterium is also widely present in the environment. Nearly one-third of the human population supports the colonization of Staphylococcus aureus and are designated as carriers.  This makes it one of the closest organism in causing sepsis and hospital acquired infections.

Transmission:  Nasal carriage of S. aureus occurs in 40-50% of humans. Major habitat in man is anterior nares or on skin elsewhere.  Hospitalised patients as well as medical and paramedical staff show higher incidence of carriage of Staph. aureus.  Several coagulase negative species of staphylococci are present on the skin as commensal normal flora.  

Morphology:  These are non motile, non spore forming, Gram positive cocci which measure around 0.7 to 1.2 μm in diameter. These are characteristically grouped in irregular clusters that resemble bunches of grapes.   This appearance is because of incomplete separation of cells after successive cell divisions which take place in perpendicular planes. Instead of residual attachment along the plane of division, the attachment point is usually eccentric to the plane of division. This results in irregular aggregates of cocci. The clusters are usually seen in growth obtained on solid media or in pathological materials.  When cultivated in liquid medium, staphylococci usually form short chains.  Single cocci, pairs or tetrads are also seen in liquid cultures.  

Growth and growth factors:  These are easy to grow organisms. They prefer aerobic environment but can also grow in the absence of oxygen; range of temperature for growth is 6-44°C (optimum 37°C) and the range of pH is 4.2-9.3 (optimum 7). The organisms grow easily in simple liquid media especially nutrient broth and peptone water. In both these media the growth becomes visible as uniform turbidity.  

Susceptibility to Physical and Chemical Agents:  Staphylococci are extremely hardy organisms and can survive in adverse environment for a very long time. Some strains can even withstand temperature of 60^oC for 30 minutes.  As compared to other bacteria these are more resistant to the action of disinfectants.  Staph. aureus is very sensitive to aniline dyes and a concentration of 1:500,000 of crystal violet can inhibit their growth.  Most strains can grow in the presence of 10% NaCl.  Fatty acids inhibit the growth of staphylococci.  

Biochemical Properties: There is no consistent pattern of biochemical reactions for Staph. aureus.  The single most important test to differentiate Staph. aureus from Staph. epidermidis is the production of coagulase. Approximately 97% of staphylococci isolated from pathological lesions elaborate this enzyme.  For remaining three percent, one has to resort to testing of DNAse to label it as Staph. aureus. They ferment a number of sugars producing acid but no gas. Fermentation of mannitol is of particular use since it is positive only for Staph. aureus strains.

RELATED;

1.  STREPTOCOCCUS  

2.  VIDEO DEMONSTRATION BACTERIAL CELL WALL

3.  NOSOCOMIAL INFECTIONS

4.  NORMAL FLORA OF THE HUMAN BODY

REFERENCES

MEGA MOVER EMPIRE

INTRODUCTION: This page in names of Mega “Mover Empire” was created by Godfrey Kateregga Muwanga, in the year 2021 in middle of the first lock-down aggravated by COVID 19 pandemic. This pandemic was one of it’s kind and to be sincere, I had never seen one in my life time. In my country Uganda, things went as worse as closure of all schools and public services such as shops, transport, hotels and bars and for the two years 2021 and 2022, there was no school running throughout the country. 

Now within that period, you could think about a medical student to at least have electronic means of accessing notes in order to stay updated until when school time normalized. With the Standard Operating Procedures (SOPs) tightened, interpersonal distance was put to the limit and this could only be achieved by owning a gadget such as a smartphone, tablet or a personal computer. But even so, it could still require one to have technical know how especially when it comes to use of electronic gadgets, something not every student's immediate demand.  

EMERGENCY OF THIS PAGE:  As a well wisher, this is when I and my friend Joseph came up with an idea of doing something for the future medical generation. This page surfaces on Google with as in the link below,

MEGA MOVER EMPIRE 

It is also available on YouTube with the link below,

MEGA MOVER EMPIRE ON YOUTUBE

On Quora with the link below;

MEGA MOVER EMPIRE ON QUORA

LinkedIn, Reddit, Gainrep and other social media.

Godfrey Kateregga Muwanga is a Ugandan medical and social writer, graduate from Mbarara University of Science and Technology (M.U.S.T.), Faculty of Medicine, in Western Uganda accessible at www.must.ac.ug. Mbarara University of Science and Technology is located in the Western City of Mbarara, in the locally known as Ankole region with it’s Faculty of Medicine attached to Mbarara Regional Referral Hospital.

RELATED;

1.  MASAKA, THE OLDEST CITY IN BUGANDA KINGDOM

2.  CONSEQUENCES OF COVID 19 INDUCED LOCKDOWN

ZIDOVUDINE

 

Introduction:  This drug was previously known as azidothymidine (AZT).  It is a deoxythymidine analog that is well absorbed (63%) and distributed to most body tissues and fluids, including the cerebrospinal fluid, where drug levels are 60–65% of those in serum.  Zidovudine was the first antiretroviral agent to be approved and has been well studied.  Zidovudine is available in a fixed-dose combination formulation with lamivudine, either alone or in combination with abacavir.  The drug has been shown to decrease the rate of clinical disease progression and prolong survival in HIV-infected individuals.

Subclass:  Nucleoside Reverse Transcriptase Inhibitor (NRTI).

Pharmacokinetics:  Zidovudine is eliminated primarily by renal excretion following glucuronidation in the liver. 

Maternal and Child health indications:  In pregnancy, a regimen of oral zidovudine beginning between 14 and 34 weeks of gestation, intravenous zidovudine during labor, and zidovudine syrup to the neonate from birth through 6 weeks of age has been shown to reduce the rate of vertical (mother-to-newborn) transmission of HIV by up to 40%. 

Side effects:  The most common adverse effect of zidovudine is myelosuppression, resulting in macrocytic anemia or neutropenia.  Gastrointestinal intolerance, headaches, and insomnia may occur but tend to resolve during therapy. Lipoatrophy appears to be more common in patients receiving zidovudine or other thymidine analogs.  Less common toxicities include thrombocytopenia, hyperpigmentation of the nails, and myopathy. High doses can cause anxiety, confusion, and tremulousness.

RELATED;

1.  ABACAVIR  

2.  LAMIVUDINE

3.  Pharmacology and therapeutics

MARAVIROC

 Pharmacodynamics:  Maraviroc binds specifically and selectively to the host protein CCR5, one of two chemokine receptors necessary for entrance of HIV into CD4+ cells.

Indications:  Maraviroc is approved for adults with CCR5-tropic (also known as R5) HIV-1 infection who are experiencing virologic failure due to resistance to other antiretroviral agents.  Since maraviroc is active against HIV that uses the CCR5 co-receptor exclusively, and not against HIV strains with CXCR4, dual, or mixed tropism, tropism testing should be performed before initiating treatment with maraviroc.

Pharmacokinetics:  The absorption of maraviroc is rapid but variable, with the time to maximum absorption generally being 1–4 hours after ingestion of the drug. Most of the drug (≥ 75%) is excreted in the feces, whereas approximately 20% is excreted in urine. The recommended dose of maraviroc varies according to renal function and the concomitant use of CYP3A inducers or inhibitors.  Maraviroc has been shown to have excellent penetration into the cervicovaginal fluid, with levels almost four times higher than the corresponding concentrations in blood plasma.

Contraindications:  Maraviroc is contraindicated in patients with severe or end-stage renal impairment who are taking concurrent CYP3A inhibitors or inducers, and caution is advised when used in patients with preexisting hepatic impairment and in those co-infected with HBV or HCV.

Drug-drug interactions:  Maraviroc is a substrate for CYP3A4 and therefore requires adjustment in the presence of drugs that interact with these enzymes. It is also a substrate for P-glycoprotein, which limits intracellular concentrations of the drug. The dosage of maraviroc must be decreased if it is co-administered with strong CYP3A inhibitors (eg, delavirdine, ketoconazole, itraconazole, clarithromycin, or any protease inhibitor other than tipranavir) and must be increased if co-administered with CYP3A inducers (eg, efavirenz, etravirine, rifampin, carbamazepine, phenytoin, or St. John’s wort).

RELATED;

1.  ANTIVIRAL DRUGS

2.  ZIDOVUDINE

3.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

CHAPTER ONE OF THE RESEARCH REPORT

CHAPTER ONE OF THE RESEARCH REPORT:  This is the very first part of the research project or in simple terms that curtain riser for any research student.  On this page, let us look at some of the components of the chapter explained in details.

COMPONENTS OF CHAPTER ONE

1.0  Introduction:  The introduction part basically is always the initial part of any chapter and the content here will just be the summarized components of that specific chapter.  By reading through the introduction, I should be able to know the different sections that you are talking about.

1.1  Background of the study:  In this section, the student put some information concerning the research study and this summery of literature should be giving the read an insight of what is going on with the study.  In quantity, this section should be at least 3 paragraphs and not exceeding 1 and half a page.  There is a common mistake that students sometimes write a lot of literature which would actually be presented in chapter two.

Chapter two: Literature review

1.2  Problem statement

1.3  Purpose of the study

1.4  Objective of the study

1.5  Justification of the study:  In this section of the medical research report, there should be written the summery of the evidence that the problem stated does actually occur with relevant parameters cited.  We have already talked about the problem statement and in case you want to read more about it click here.

RELATED;

1.  HOW TO WRITE A RESEARCH PROPOSAL

2. THE RESEARCH STUDY DESIGNS

3.  THE MEDICAL RESEARCH PROBLEM STATEMENT

CALCULATION OF SAMPLE SIZE-FORMULA 1

SAMPLE SIZE CALCULATION

FORMULAR 1:  Calculation of sample size in medical research is one of the most important steps towards data collection and a well predetermined sample size will generate sufficient data required.  In a series of discussion, we will be looking at the most common formulae used in calculation of sample size.

Where,

1. n is the required sample size,

2. Z is a tabulated value in relation to the significance level of the study that is to say, 1.96 for α=0.05

3. d is the standard deviation of the variable in the study basing on previous studies.

4. p is the proportion of the population to be estimated

5. And e is the tolerance measurement error.

 

RELATED;

1.  STRATEGIES FOR DETERMINING SAMPLE SIZE

2.  SAMPLING

3.  SAMPLE SIZE CALCULATION FORMULA 3

REFERENCES

ETHAMBUTOL

INTRODUCTION: Ethambutol is a synthetic, water-soluble, heat-stable compound, dispensed as the dihydrochloride salt.

MECHANISM OF ACTION & CLINICAL USES: Susceptible strains of Mycobacterium tuberculosis and other mycobacteria are inhibited in vitro by ethambutol, 1–5 mcg/mL. Ethambutol inhibits mycobacterial arabinosyl transferases. Arabinosyl transferases are involved in the polymerization reaction of arabinoglycan, an essential component of the mycobacterial cell wall. The bacterial cellwall

Resistance to ethambutol is due to mutations resulting in overexpression of emb gene products or within the embB structural gene.

PHARMACOKINETICS: Ethambutol is well absorbed from the gut. After ingestion of 25 mg/kg, a blood level peak of 2–5 mcg/mL is reached in 2–4 hours. About 20% of the drug is excreted in feces and 50% in urine in unchanged form. Ethambutol accumulates in renal failure, and the dose should be reduced by half if creatinine clearance is less than 10 mL/min. Ethambutol crosses the blood-brain barrier only when the meninges are inflamed. Concentrations in cerebrospinal fluid are highly variable, ranging from 4% to 64% of serum levels in the setting of meningeal inflammation. As with all antituberculous drugs, resistance to ethambutol emerges rapidly when the drug is used alone. Therefore, ethambutol is always given in combination with other antituberculous drugs.

Ethambutol hydrochloride, 15–25 mg/kg, is usually given as a single daily dose in combination with isoniazid or rifampin. The higher dose is recommended for treatment of tuberculous meningitis. The dose of ethambutol is 50 mg/kg when a twice-weekly dosing schedule is used.

ADVERSE REACTIONS: Hypersensitivity to ethambutol is rare. The most common serious adverse event is retrobulbar neuritis, resulting in loss of visual acuity and red-green color blindness. This dose-related adverse effect is more likely to occur at dosages of 25 mg/kg/d continued for several months. At 15 mg/kg/d or less, visual disturbances are very rare. Periodic visual acuity testing is desirable if the 25 mg/kg/d dosage is used. Ethambutol is relatively contraindicated in children too young to permit assessment of visual acuity and red-green color discrimination.

RELATED;

1. ISONIAZID  

2. TUBERCULOSIS  

3. MYCOBACTERIA

4.  STREPTOMYCIN

REFERENCES

PHYSICAL AND CHEMICAL BARRIERS TO INFECTION

INTRODUCTION:  The skin:  The squamous epithelium of the skin is the first line of defense against microorganisms encountered in the outside world. As keratinized epithelial surface cells desquamate, the skin maintains its protective barrier by generating new epithelial cells beneath the surface. The skin is also bathed with oils and moisture from the sebaceous and sweat glands. These secretions contain fatty acids that inhibit bacterial growth. Poor vascular supply to the skin may result in skin breakdown and increased susceptibility to infection. For example, chronically debilitated or bedridden patients may suffer from presacral pressure ulcers as a result of constant compression of this dependent body area; these ulcers allow direct entry of skin and enteric bacteria into previously sterile sites and predispose patients to severe infections.

The mucus membranes:  The mucous membranes also provide a physical barrier to microbial invasion. The mucous membranes of the mouth, pharynx, esophagus, and lower urinary tract are composed of several layers of epithelial cells, whereas those of the lower respiratory tract, the GI tract, and the upper urinary tract are delicate single layers of epithelial cells. These membranes are covered by a protective layer of mucus, which traps foreign particles and prevents them from accessing the lining of epithelial cells. Because mucus is hydrophilic, many substances produced by the body easily diffuse to the surface, including enzymes with antimicrobial activity such as lysozyme and peroxidase.

RELATED;

1.  SPECIFIC IMMUNITY  

2.  PASSIVE IMMUNISATION

3.  DYNAMICS OF INFECTIOUS DISEASES

REFERENCES

REPLICATED CROSS-SECTIONAL DESIGN

 

Objectives of the discussion:  

Introduction:  This study design is based upon the assumption that participants at different stages of a programme are similar in terms of their socioeconomic–demographic characteristics and the problem for which they are seeking intervention. Assessment of the effectiveness of an intervention is done by taking a sample of clients who are at different stages of the intervention.  The difference in the dependent variable among clients at the intake and termination stage is considered to be the impact of the intervention.

RELATED;

1.  EXPERIMENTAL STUDY DESIGN

2.  RESEARCH METHODOLOGY

RETROSPECTIVE–PROSPECTIVE STUDY

INTRODUCTION:  A retrospective–prospective study focuses on past trends in a phenomenon and studies it into the future. A study where you measure the impact of an intervention without having a control group by ‘constructing’ a previous baseline from either respondents’ recall or secondary sources, then introducing the intervention to study its effect, is considered a retrospective–prospective study. In fact, most before-and-after studies, if carried out without having a control – where the baseline is constructed from the same population before introducing the intervention – will be classified as retrospective-prospective studies.

RETROSPECTIVE STUDY:  A retrospective study investigates a phenomenon, situation, problem or issue that has happened in the past. Such studies are usually conducted either on the basis of the data available for that period or on the basis of respondents’ recall of the situation.

RELATED;

1.  THE CROSS-SECTION STUDY DESIGN  

2.  THE EXPERIMENTAL STUDY DESIGN

3.  THE RETROSPECTIVE STUDY DESIGN

REFERENCES

THE SATURATION POINT IN QUALITATIVE RESEARCH METHODS

INTRODUCTION:  Previously we have been looking at determination of sample size in a research project and in some of our discussions we noted that unlike in quantitative research methods, in the qualitative research methods we do not have a predetermined sample size.  Data is collected until no more new ideas and issues are coming up, and this is what we call the saturation point.  

THE CONCEPT OF DATA STATURATION:  The concept of saturation point refers to the stage in data collection where you, as a researcher, are discovering no or very little new information from your respondents. In qualitative research this is considered an indication of the adequacy of the sample size.  And therefore termed "The saturation point".  At this point the researcher will terminate the data collection process and continue with the next step of the research report.

POINT TO NOTE:  Although the saturation point may seem a little like 4-10 respondents, sometimes as a researcher you have to be a little patient and increase the number more than that, to be sure that all the possible responses are captured.

Sometimes you feel saturated at a lower number and by increasing the number or continuing to collect more data from more respondents, you notice fresh and very new ideas not explored before.  What I would say for that matter is that; collect data from as many respondents as possible.

RELATED;

1.  Qualitative research

2.  Sample size determination

3.  Research methodology

References

DIPHENHYDRAMINE

Therapeutic Class: Drug to treat allergies

Pharmacologic Class: H₁-receptor antagonist; antihistamine

ACTIONS AND USES: Diphenhydramine is a first-generation H1-receptor antagonist whose primary use is to treat minor symptoms of allergy and the common cold such as sneezing, runny nose, and tearing of the eyes. Diphenhydramine is often combined with an analgesic, decongestant, or expectorant in OTC cold and flu products. Diphenhydramine is also administered topically to treat rashes, and intramuscular/intravenous (IM/IV) forms are available for severe allergic reactions. Other indications for diphenhydramine include Parkinson’s disease, motion sickness, and insomnia.

ADMINISTRATION ALERTS: There is an increased risk of anaphylactic shock when this drug is administered parenterally. When administering IV, inject at a rate of 25 mg/min to reduce the risk of shock. When administering IM, inject deep into a large muscle to minimize tissue irritation.

Pregnancy category: C

ADVERSE EFFECTS: First-generation H1-receptor antagonists such as diphenhydramine cause significant drowsiness, although this usually diminishes with long-term use. Occasionally, paradoxical CNS stimulation and excitability will be observed, rather than drowsiness. Excitation is more frequent in children than adults. Anticholinergic effects such as dry mouth, tachycardia, and mild hypotension occur in some patients. Diphenhydramine may cause photosensitivity.

Contraindications: Hypersensitivity to the drug, prostatic hypertrophy, narrow-angle glaucoma, and gastrointestinal (GI) obstruction are contraindications of use. The drug should be used cautiously in patients with asthma or hyperthyroidism.

INTERACTIONS: Drug–Drug: Use with CNS depressants such as alcohol or opioids will cause increased sedation. Other OTC cold preparations may increase anticholinergic side effects. Monoamine oxidase (MAO) inhibitors may cause a hypertensive crisis.

Lab Tests: Drug should be discontinued at least 4 days prior to skin allergy tests; otherwise, false-negative tests may result. Treatment of Overdose: Overdose may cause either CNS depression or excitation. There is no specific treatment for overdose

RELATED;

1. SHOCK  

2. ASTHMA  

3.  DRUG USE IN RELATION TO PREGNANCY  

4.  TOXICITY OF DRUGS AND ANTIDOTES

references

THE BACTERIAL CELL WALL

THE BACTERIAL CELL WALL:  The bacterial cell wall is quite different from the plasma membrane of the animal cell and the plant cell wall.  To differentiate and understand bacteria, staining techniques have been used to describe the morphology of the different strains.  Here, we are going to look at three ways of categorizing microbes as Gram positives, Gram negatives and acid fast bacilli.  The bacterial cell just like the human cell, has a cytoplasmic cell membrane, and then depending on the morphology, additional cell layers are superimposed as we are going to be seeing below.

THE GRAM POSITIVE BACTERIA:  In addition to the cytoplasmic membrane, gram positive bacteria has a second layer which is thicker, and this is known as the peptidoglycan layer.

THE GRAM NEGATIVE BACTERIA

ACID FAST BACILLI:  For the gram negatives, there is a third layer in addition to the plasma membrane and the peptidoglycan layer, and this is known as the lipopolysaccharide layer.

THE ACID FAST BACILLI:  For acid fast bacilli, apart from the cytoplasmic membrane, there is addition extra two special layers for Mycobacteria; the arabinogalactan and mycolic acid

OTHER EXTRACELLULAR BACTERIAL COMPONENTS

RELATED;

1.  COMPONENTS OF THE BACTERIAL CELL WALL

2.  THE PLASMA MEMBRANE

HELICOBACTER PYLORI

INTRODUCTION:  Morphology and culture:  H. pylori are spirally shaped, Gram-negative rods with lophotrichous flagellation. Cultures from stomach biopsies are grown on enriched mediums and selective mediums under microaerobic conditions for three to four days. Identification is based on detection of oxidase, catalase, and urease.

Pathogenesis and clinical pictures:  H. pylori occurs only in humans and is transmitted by the fecal-oral pathway. The pathogen colonizes and infects the stomach mucosa. The pathogenicity factors include pronounced motility for efficient target cell searching, adhesion to the surface epithelial cells of the stomach, urease that releases ammonia from urea to facilitate survival of the cells in a highly acidic environment and a vacuolizing cytotoxin that destroys epithelial cells.  Once the pathogen has infected the stomach tissues an acute gastritis results, the course of which may or may not involve overt symptoms. Potential sequelae include:

1. Mild chronic gastritis that may persist for years or even decades and is often asymptomatic.

2. Duodenal ulceration, sometimes gastric ulceration as well.

3. Chronic atrophic gastritis from which a gastric adenocarcinoma sometimes develops.

4. Rarely B cell lymphomas of the gastric mucosa.

Diagnosis:  Histopathological, cultural and, molecular identification of the bacteria in stomach lining biopsies. A noninvasive breath test involving ingestion of 13C-labeled urea and measurement of 13CO2 in the expelled air.  Antigen detection in stool. Antibodies can be identified with an ELISA or Western blotting.

Therapy:  In patients with ulcers and/or gastritis symptoms, a triple combination therapy with omeprazole (proton pump blocker), metronidazole, and clarithromycin lasting seven days is successful in 90% of cases.

Epidemiology:  Based on sero epidemiological studies we know that H. pylori occur worldwide. Generalized contamination of the population begins in childhood and may reach 100% in adults in areas with poor hygiene. The contamination level is about 50% among older adults in industrialized countries. Transmission is by the fecal-oral route.

RELATED;

1.  NORMAL FLORA OF THE HUMAN BODY 

2.  ENTEROBACTERIACEAE

3.  HAEMOPHILUS INFLUEZAE

4.  PSEDOMONAS AERUGINOSA

5.  PEPTIC ULCER DISEASE

REFERENCES

SAMPLE SIZE CALCULATION FORMULA 3

SAMPLE SIZE CALCULATION FORMULA 3

 

Where;

1.  n is the estimated sample size

2. t is the statistic that defines the level of risk.  That is, 2 for α=0.05

3. d is the degree of precision expressed in terms of proportion.

4. p is the proportion of the population to be estimated and

5. e is the tolerance measurement error.

RELATED;

1.  CALCULATION OF SAMPLE SIZE-FORMULA 1

2.  SAMPLING DESIGNS

REFERENCES