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  • Allopathy medicine awareness article for doctors & hospitals.

  • Can't cover everything in this small article

  • Won't cover antivirals, Antifungals, Anthelminthic drugs here

  • Lots will remain unanswered

  • Not everyone will be happy

  • But everyone will take something home

  • All we can do is initiate a curiosity of research and understand what is wrong/right


  • Antibiotics

  • Antibacterial

  • Antimicrobial

  • Antiviral

  • Anthelminthic

  • Antifungal

  • Antibacterial

Case Discussion 1 -

A 55 year lady, was operated for hysterectomy 5 days back. She went home, started having fever 2 days back and now brought with altered sensorium, Low urine Output. On Examination, HR=130, Pulse Feeble BP=80/50 RR=38 SPO2 - 92% on air CVS - cold extremities CNS - Confused, drowsy

What do you think could have happened?

  • What is septicemia / Bacteremia?

  • What is sepsis?

What will you do?

  • Give Antibiotics?

  • Which one??

Likely Pathogens - Seek information from local Pathologist/Microbiologist Life is a constant fight against infection

  • Bacteria are all around us

  • Skin, Gut, Air, Soil, ….

But Bacteria is not always Bad

  • Gut bacteria

  • Problems with antibiotics

  • Harmful bacteria grow

  • Probiotics

  • Daralac, Sporolac, Curd, Vitamin B, etc.,

  • Normal vs C-Section babies exposure to mother's bacteria is different.

Why does infection occur?

  • Weakened defenses or hygiene problem

  • Pathogenic bacteria enter from other locations

  • Salmonella

Back to case discussion on Septicemic Shock

How Bacteria enters the body? - Portal of Entry

  • Skin

  • Upper Respiratory Tract

  • GI Tract

  • Urogenital Tract

  • Tubes and Punctures - including bites

Skin and Soft Tissue Infection SSTI

Skin, subcutaneous tissue, fascia, and muscle

  • Impetigo

  • Folliculitis

  • Furuncle

  • Carbuncle

  • Erysipelas

  • Cellulitis

  • Necrotizing Fascitis

Organisms causing skin and soft tissue infection

  • Gram Positive Cocci - Staphylococcus aureus

  • Streptococcus pyogens

  • Site specific - gram negative bacilli in Perianal abscess

  • Immunocompromised - pseudomonas, enterococcus

Classification of Bacteria

  • Cocci (ball) & Bacilli (rod)

  • Gram Positive (Changes to Purple) & Negative (Pink)

  • Aerobic (w/ O2) & Anaerobic (w/o O2)

  • Skin infections are usually Gram Positive Cocci

Empiric Therapy

There are hundreds of antibiotics

  • Why so many antibiotics needed?

  • Resistance, side effects, many new bacteria growth

  • How antibiotics work?

  • Most drugs act on patient, his organs, receptors

  • Antibiotic should be toxic to the bacteria but not to humans

Cell wall and Ribosome 70S are two things that differentiate bacteria from us.

Antibiotics that inhibit Cell Wall Synthesis

  • More than 60% antibiotics act by inhibiting cell wall synthesis

  • Beta Lactam Antibiotics

  • Glycopeptides

  • Penicillin

General structure of Penicillins

  • Beta-Lactam Ring -> Beta Lactamase -> enzymes -> Bacterias shared those enzymes

  • Doctors started Beta Lactamase Inhibitors

  • Amoxicillin + Clavulanic acid is used to treat certain infections caused by bacteria, including infections of the ears, lungs, sinus, skin, and urinary tract. Amoxicillin is in a class of medications called penicillin-like antibiotics. It works by stopping the growth of bacteria.

  • Piperacillin + tazobactam, sold under the brand name Zosyn among others, is a combination medication containing the antibiotic piperacillin and the β-lactamase inhibitor tazobactam. The combination has activity against many Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa

  • Unasyn (Ampicillin + Sulbactam) is a combination antibiotic medication containing ampicillin and sulbactam. It is used to treat a wide variety of bacterial infections -

  • meningococcal meningitis.

  • bacterial meningitis caused by Streptococcus.

  • infection of the biliary tract.

  • pneumonia caused by bacteria.

  • diverticulitis.

  • E. coli bacteria infection of abdominal cavity lining.

  • Klebsiella pneumoniae infection of abdominal cavity lining.


  • Skin infections - Gram +ve - Amoxicillin + Clavulanic acid (Gen 1, 2)

  • Intra abdominal / cepsis - Gram -ve - Piperacillin + tazobactam (Gen 3,4)

Upper Respiratory Tract

  • Nasopharyngeal infection

  • Sinusitis

  • Otitis media

  • Epiglottitis

  • Laryngitis

  • Tracheobronchitis

  • Pneumonia

Organisms causing URTI

  • Rhinoviruses

  • Coronaviruses

  • Adenoviruses

  • Coxsackieviruses

  • In general adult URTI is by these viruses, So don't give antibiotics. Administer steam, decongestant, anti-inflammatory, etc.,

  • 8-10-12 age kids can get Gram Positive Cocci bacteria - Streptococcus. If not treated well it can turn into Rheumatic fever & Rheumatic heart disease. Amoxicillin / Co-amoxiclav / Ampicillin can be administered.

  • Non typeable H influenzae, and Moraxella catarrhalis

Lower Respiratory Tract

  • Pneumonia

  • Community acquired

  • Pneumonaiae, H.influenzae, Legionnella, E.coli, Klebsiella sp., S.aureus

  • Levofloxacin 500 OD (7 days)

  • Amoxycillin 500 - 1gm TDS

  • IV Mox-clav 1.2 gm TDS or Ceftriaxone 2 gm OD

  • Upgrade - (Escalate quickly, deescalate slowly)

  • Piperacillin Tazobactam

  • Meropenem

  • Cefoperazone sulbactam

  • MRSA is a doubt

  • Linezolid 600 IV / Oral BD

  • Atypical - Doxycline 100 BD or Azithromycin 500 OD

  • Hospital acquired

  • Entero-bacteriaceae, Pseudomonas spp., Acinetobacter spp. (Gram -ve)

  • Treatment

  • Piperacillin-tazobactam 4.5g IV q6h or Cefoperazone-sulbactam 3g IV q8h

  • Upgrade -

  • Imipenem 1g IV q8h or meropenem

  • Modify based on culture of lower respiratory secretions.

Antibiotics that inhibit Ribosome 50s Macrolides

  • More effective in Lung infections because they concentrate in Lung macrophages

  • Thromycin

  • Erythromycin

  • Azithromycin

  • Roxithromycin

Cidal and Static

  • Those antibiotics which kill the bacteria are bactericidal. E.g., Beta lactams, Floxacin

  • Those which inhibit the growth of bacteria without killing it are termed bacteriostatic

  • E.g., Doxycline, Macrolides

  • If patient has taken antibiotics in past 90 days, then we don't give static antibiotics.

GI Tract

  • Diarrhea

  • Intraabdominal infection

  • Parasitic infection

  • Salmonella

Acute Gastroenteritis

  • Viral

  • Enterotoxigenic E Coli

  • Treatment

  • Rehydration

  • No Antibiotics (unless Dysentery)

  • If Dysentery - Metronidazole, Nitazoxamide, Diloxanide Furate (for amoebic)

  • Ciprofloxacin 500 BD for bacillary dysentery

Enteric Fever / Typhoid

  • Cephalosporin

  • Oral - Cefixime 200 BD 14 days / Azithromycin 500 BC x 7 days

  • IV - Ceftriaxone 2 gm IV BD

Intra abdominal infections

  • Biliary tract infections (cholangitis, cholecystitis)

  • Spontaneous bacterial Peritonitis

  • Secondary peritonitis, Intra-abdominal abscess / GI perforation

  • Post necrotizing pancreatitis: infected pseudocyst; pancreatic abscess

  • Sick Patient, upgrade to -

  • Piperacillin/tazobactam 4.5 gm IV 8 Hrly

  • Addition of cover for yeast (fluconazole IV 800 mg loading dose day 1, followed by 400 mg 2nd day onwards)

  • Enterococcus (vancomycin / teicoplanin) may be contemplated

Gram Negative Bacteria (Bacilli - rods)

  • Enterobacteriaceae

  • E Coli

  • Klebsiella

  • Proteus

  • Shigella / Salmonella

  • Pseudomonas (It’s a monster. Administer: Piperacillin Tazobactam)

  • Severe

  • Meropenem 1 gm IV 8 hrly

  • Or

  • Imlpenem Cilastatin 500 mg IV 6 hourly

  • To cover Anaerobic - Metronidazole 400 8hrly IV

Antibiotics for Enterobacteriaceae

  • Third Generation Cephalosporins

  • Ceftriaxone 2gm IV OD

  • Cefoperazone Sulbactam

  • Fluoroquinolones

  • Floxacins

Anaerobic Bacteria

  • Clostridium

  • Peptostreptococcus

  • Bacteroids

Anaerobic Bacteria - Classification

  1. Gram-negative bacilli (curved, spirals & spirochete forms) - Bacteroids, Borrelia, Butyrivibrio, Capnocytophaga, Campylobacter, Fusobacterium, Leptotrichia, Porphyromonas, Prevotella, Treponema, etc.,

  2. Gram-positive cocci - Anaerococcus, Coprococcus, Micromonas, Peptococcus, Peptostreptococcus, Streptococcus, Gemella, etc.,

  3. Nonsporing Gram-positive bacilli - Actinomyces, Arcanobacterium, Bifidobacterium, Eubacterium, Lactobacillus, Methanobacterium, Mobiluncus, Propionibacterium, etc.,

  4. Gram-negative cocci - Acidaminococcus, Anaeroglobus, Veillonella

Anaerobic Bacteria coverage

  • Metronidazole / Tinidazole tab 400 mg / IV

  • For groin, vagina, belly region (abdomen and Genito-urinary tract) coverage

  • Clindamycin - C 150 mg

  • Any other region coverage than groin, belly region said for Metronidazole.

  • Suppresses protein synthesis by binding to 50S ribosomal subunits

  • Anaerobic Bacteria

  • Bite wounds

  • PID

Genitourinary Tract

  • Acute uncomplicated Cystitis

  • Acute uncomplicated Pyelonephritis

  • Enterobacteriaceae

  • Streptococcus saprophyticus

Choice of Antibiotics in Acute uncomplicated UTI

  • Levofloxacin 500 OD (not effective nowadays)

  • Nitrofurantoin 100 mg BD x 5 Days (old drug, sulpho based, first choice in US)

  • Bactrim DS (Cotrimoxazole)

  • Fosfomycin

  • Fosfomycin is a bactericidal, activity against several bacteria including multidrug resistant Gram-negative bacteria, by irreversibly inhibiting an early stage in cell wall synthesis.

  • Acute Cystitis

  • Multi-drug resistant UTI: 2-3 g PO every 2-3 days for 3 doses

Aminoglycosides - For Hospitalized UTI

  • Gentamycin

  • Amikacin

  • Piperacillin/tazobactam

  • Monitor renal function closely and rationalize according to culture report

  • Complete total duration of 14 days

Tubes and Punctures

  • Endocarditis

  • Vehicle borne diseases

If it is Tubes & Punctures, its Hospital related

  • Causative Organism - Pseudomonas (Gram-ve in immunocompromised patients, blue-green), Klebsiella, Enterococcus, MRSA

  • Piperacillin/tazobactam

  • Meropenem

  • Clindamycin

  • Vancomycin

Anti Pseudomonas

  • Antipseudomonal beta lactam

  • Piperacillin

  • Ceftazidime

  • Cefepime

  • Imipenem

  • Aztreonam

  • +

  • Aminoglycoside

  • Tobramycin

  • Gentamycin

  • Amikacin

  • or

  • Fluoroquinolones

  • Ciprofloxacin

  • Levofloxacin

MRSA (Gram +ve)

  • Antibiotics

  • Glycopeptides (Safegaurd these, as the bacteria can become sensitive to these kind)

  • Vancomycin

  • Gram +ve Cocci Staphylococcus, MRSA

  • Teicoplanin

  • Gram +ve Bacteria including Enterococcus, MRSA

Factors in choice of Antibiotics

  • Supposed causative organism

  • Spectrum of activity

  • Penetration in target tissues

  • Metabolism of antibiotic and interaction

  • Patient's overall condition

  • Route of administration

  • Timing of dosage - with food

  • Cidal or static

  • Bioavailability

Three types of antibiotic treatment

  • Prophylactic

  • The person is not infected yet but has high chances

  • HCQS

  • Pre operative Antibiotics

  • Cefazolin given before surgery to prevent a Staphylococcal skin infection of the surgical site

  • Empiric

  • Confirm or suspected infection but organism is not known. Culture takes time and money.

  • This is the most common type of treatment we do.

  • And this is what we learnt till now.

  • But then, you should know the causative organisms for common infections.

  • E.g.,

  • Levofloxacin initiated for a patient with presumed community-acquired pneumonia

  • Ceftriaxone given for the treatment of suspected pyelonephritis

  • Vancomycin, tobramycin, and meropenem for a patient with probable

  • Hospital-acquired pneumonia in the intensive care unit

  • Definitive

  • We know the organism and its sensitivity.

  • Choice is for safe, effective, cheap and narrowest spectrum possible

  • E.g.,

  • Transitioning from piperacillin/tazobactam to ampicillin in a patient with a wound infection caused by Enterococcus faecalis, which is susceptible to both drugs

  • Discontinuing ceftriaxone and initiating ciprofloxacin for a patient with a UTI caused by Klebsiella pneumoniae that is resistant to ceftriaxone but susceptible to ciprofloxacin

Take home messages

  • Not every infection needs antibiotics

  • If uncomplicated, start with narrowest spectrum

  • If very serious patient, start with maximum but slowly de-escalate

  • Overuse of Antibiotics is slowly making the world difficult to live…

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