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dignosispearls · 4 years

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Solve it.... #diagnosis #neetpreparation #medicine #doctor #respiratorytherapist #aiims https://www.instagram.com/p/CEpMhcXjjwYmToP7rDEpgOFZdvniXecdFB7fpg0/?igshid=zu82fzqvmpp1

#diagnosis #neetpreparation #medicine #doctor #respiratorytherapist #aiims

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dignosispearls · 4 years

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#neetpreparation #medicine #cardio #diagnosis #doctor https://www.instagram.com/p/CEpJwn3jW60Gmhkkbw2fgnwYsUNHOWLOG2xr5Y0/?igshid=15kzj0ib8zu8y

#neetpreparation #medicine #cardio #diagnosis #doctor

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dignosispearls · 4 years

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Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common encapsulated, Aerobic, non-lactose fermenting, oxidase-positive, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug-resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes.

Pathogenesis: •phospholipase C – produced to degrade cell membranes •endotoxin, which leads to – fever, hypotension, disseminated intravascular coagulation •exotoxin A – this inactivates elongation factor 2 (EF-2), which stops protein synthesis via ADP ribosylation •pyoverdine and pyocyanin pigment – leads to a blue-green pigment

Bacteria are constantly finding new ways to avoid the effects of antibiotics. For example, some Pseudomonas can produce enzymes called carbapenemases that break down antibiotics including carbapenems, making the drugs ineffective. Carbapenem antibiotics are typically reserved to treat multidrug-resistant bacterial infections, so when bacteria develop resistance to them, treatment options can be extremely limited.

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P. aeruginosa is considered opportunistic insofar as serious infection often occurs during existing diseases or conditions – most notably cystic fibrosis and traumatic burns. It generally affects the immunocompromised but can also infect the immunocompetent as in hot tub folliculitis. Treatment of P. aeruginosa infections as mentioned earlier can be difficult due to its natural resistance to antibiotics. When more advanced antibiotic drug regimens are needed adverse effects may result.

Pseudomonal infections can involve the following parts of the body, with corresponding symptoms and signs: - Respiratory tract (eg, pneumonia) - Bloodstream (bacteremia) - Heart (endocarditis) - CNS (eg, meningitis, brain abscess) - Ear (eg, otitis externa and media) - Eye (eg, bacterial keratitis, endophthalmitis) - Bones and joints (eg, osteomyelitis) - GI tract (eg, diarrhea, enteritis, enterocolitis) - Urinary tract - Skin (eg, ecthyma gangrenosum)

#microbiology

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dignosispearls · 5 years

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Classification of in nutshell

#male and female

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dignosispearls · 5 years

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#pathology #kawasaki

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dignosispearls · 5 years

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Playing with pharmacology.... Sunday ~funday

#pharmacology #chemotherapy #mbbsinindia #kims

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dignosispearls · 5 years

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# chemotherapy 2

Antimicrobial Agents - Inhibition of DNA and Protein Synthesis

Bacterial chromosome replication

DNA replication

Bacterial Topoisomerases

maintain DNA in appropriate state of supercoiling

cut and reseal DNA

DNA gyrase (topoisomerase II) introduces negative supercoils

Topoisomerase IV decatenates circular chromosomes

these are the targets of the quinolone antibacterial agents

Quinolones

bind to bacterial DNA gyrase and topoisomerase IV after DNA strand breakage

prevent resealing of DNA

disrupt DNA replication and repair

bactericidal (kill bacteria)

Fluoroquinolone is particularly useful against

Gram +ves: Staphylococcus aureus, streptococci

Gram -ves: Enterobacteriacea; Pseudomonas aeruginosa

Anaerobes: e.g. Bacteroides fragilis

many applications e.g. UTIs, prostatitis, gastroenteritis, STIs

Adverse effects

Relatively well tolerated

GI upset in ~ 5% of patients

allergic reactions (rash, photosensitivity) in 1 - 2% of patients

Inhibition of Bacterial Protein Synthesis

Macrolides

in 1952: Erythromycin was isolated as the first macrolide (Streptomyces erythreus)

Newer macrolides: clarithromycin, azithromycin

Structurally they consist of a lactone ring (14- to 16-membered) + two attached deoxy sugars

Mode of action

bind reversibly to bacterial 50S ribosomal subunit

causes growing peptide chain to dissociate from ribosome → inhibiting protein synthesis

bacteriostatic (stops reproduction)

Macrolides’ spectrum of activity

good antistaphylococcal and antistreptococcal activity

treatment of respiratory & soft tissue infections and sensitive intracellular pathogens • e.g. Chlamydia, Legionella

Adverse effects

Generally well tolerated

nausea

vomiting

diarrhoea

rash

Aminoglycosides

large family of antibiotics produced by various species of Streptomyces (“mycin”) and Micromonospora (“micin”)

include: streptomycin, neomycin, kanamycin, gentamicins, tobramycin

Structure = linked ring system composed of aminosugars and an aminosubstituted cyclic polyalcohol

Mode of action of aminoglycosides

Bind irreversibly to 30S ribosomal subunit

disrupt elongation of nascent peptide chain

translational inaccuracy → defective proteins

bactericidal

Spectrum of activity

broad spectrum; mainly aerobic G-ve bacilli (e.g. P. aeruginosa)

used to treat serious nosocomial infections (hospital acquired infections)

First TB antibiotic

Used for cystic fibrosis

Adverse effects

all aminoglycosides have low Therapeutic Index (only a small amount needed to become toxic)

renal damage, ototoxicity, loss of balance, nausea

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dignosispearls · 5 years

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# chemotherapy

Penicillin

Penicillin is a widely used antibiotic prescribed to treat staphylococci and streptococci bacterial infections.

beta-lactam family

Gram-positive bacteria = thick cell walls containing high levels of peptidoglycan

gram-negative bacteria = thinner cell walls with low levels of peptidoglycan and surrounded by a lipopolysaccharide (LPS) layer that prevents antibiotic entry

penicillin is most effective against gram-positive bacteria where DD-transpeptidase activity is highest.

Examples of penicillins include:

amoxicillin

ampicillin

bacampicillin

oxacillin

penicillin

Mechanism(s)

Penicillin inhibits the bacterial enzyme transpeptidase, responsible for catalysing the final peptidoglycan crosslinking stage of bacterial cell wall synthesis.

Cells wall is weakened and cells swell as water enters and then burst (lysis)

Becomes permanently covalently bonded to the enzymes’s active site (irreversible)

Alternative theory: penicillin mimics D-Ala D-Ala

Or may act as an umbrella inhibitor

Resistance

production of beta-lactamase - destroys the beta-lactam ring of penicillin and makes it ineffective (eg Staphylococcus aureus - most are now resistant)

In response, synthetic penicillin that is resistant to beta-lactamase is in use including egdicloxacillin, oxacillin, nafcillin, and methicillin.

Some is resistant to methicillin - methicillin-resistant Staphylococcus aureus (MRSA).

Demonstrating blanket resistance to all beta-lactam antibiotics -extremely serious health risk.

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dignosispearls · 5 years

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Classification of chemotherapy in nutshell

#pharmacology #chemotherapy

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