6. antibiotics + superbugs

Vancomycin: Mechanism of action

Acts by binding to Peptidoglycan strand of cell wall and preventing further growth → kills bacteria

Effective against MRSA

Vancomycin: Pharmacokinetics

Not absorbed from the GI, wont enter the blood

Excreted unchanged via the kidneys

Vancomycin: Clinical uses

Oral, for serious GI infection (C. diff pseudomembranous colitis)

Slow infusion, serious systemic infection (suffering from MRSA)

Bolus IV injection: ‘Red man syndrome

Aminoglycosides names

Gentamicin, Tobramycin, Amikacin

aminogycosides: mechanism of action

Bind to 30 S subunit and inhibit protein synthesis

aminoglycosides: clinical uses 

Virtually the same spectrum as Fluroquinolones plus Enterococci

Used for Sepsis, Pneumonia

can be bactericidal or bacteriostatic

Given only IV, at low cost ($3/day).

Drug monitoring required

Hardest drugs to dose, Narrow Therapeutic Window

Side effects of aminoglycoside **KNOW ALL

Vestibular toxicity loss of balance, hearing and dizziness (Ototoxic) (Irreversible)

Renal toxicity (Reversible) Monitor Creatinine (Nephrotoxic)

Neuromuscular blockade can occur during surgery because Aminoglycosides can have an additive effect with paralyzing agents

Adding Furosemide or other nephrotoxic drugs increases risk of renal damage

Can also happen if patient is given an overdose.

The following antibiotic is a drug of choice for gram –ve anerobic infections:
1. Tetracycline
2. Amoxicillin
3. Metronidazole
4. Cephalexin

3. Metronidazole

Superbugs!!

Superbugs are not often extra virulent—but they have developed a resistance to antibiotics

Antibiotic-resistant superbugs are a serious threat

The CDC estimates that each year, antibiotic-resistant bacteria and fungi cause 2.8 million infections in the US with more than 35,000 deaths

MRSA- Methicillin resistant Staph aureus

Isolate patient and wash hands!!

Rx: Vancomycin 1g IV q12h

Bactrim (Sulfamethoxazole + Trimethoprim)

Resistant to all Penicillins and Cephalosporins

VRE- (Vancomycin resistant enterococci)

Infects immunocompromised patients

Routine identification procedures in critical care areas with isolation of
colonized patients.

Enterococci

The Enterococcus genus of bacteria are a menace for patients in healthcare settings

• Long-term healthcare facilities

• Organ transplant hospitals

• Intensive care unit

Roughly 30% of healthcare-related enterococcal infections are resistant to Vancomycin

This vancomycin-resistant strain of enterococci (VRE) bacteria is becoming increasingly resistant to additional antibiotics, meaning the remaining
antibiotics used to treat VRE may become less effective in the future.

VRSA- Vancomycin resistant Staph. aureus

Appearance has been feared and predicted the last 20 years.

Has the potential to set medicine back 100 years.

1st reported case in Detroit Mich. Sept. 2002.

Acinetobacter baumannii

can survive on surfaces for a long time

Contaminates shared medical equipment and facility surfaces

A. baumannii infections occur in intensive care units, which can lead to developing pneumonia, bloodstream infections, and urinary tract infections

When recovered from the healthcare setting it is resistant to carbapenem class antibiotics, which are used to treat these types of infections

Some A. baumannii can be resistant to nearly all antibiotics

The CDC estimates it caused 8,500 cases of infection in hospitalized patients, leading to 700 estimated deaths.

Shigella

Less than 5% of Shigella infections involved a decreased susceptibility to azithromycin in 2014, but that number grew to 24% by 2024

Shigella can cause diarrhea, fever, and abdominal pain.

Infection control is difficult because it spreads easily between people through contact with feces, or in contaminated water or food.

Dental instruments inappropriately sterilized!