By the numbers
2 million patients in the United States get an infection as a result of a hospital stay.
$122 million is the annual cost of antimicrobial resistance amongst a single pathogen
(Staphylococcus aureus).
70% of the bacteria are resistant to at least one drug.
What are the most common patient mistakes with antibiotics?
Asking for antibiotics they don't need (viral infections)
Not taking antibiotics as prescribed
Stopping before the prescription runs out (encourage resistance)
Saving antibiotics and later self-prescribing them.
Why they don’t take them (Sanson-Fisher et al)
No patients take pills more than 3 times daily.
No patients take a medication for more than 5 days in a row.
No patients take medication that makes them feel worse.
No patients pay more than $15 of their own money for a prescription.
Private lives of bacteria
Bacteria have an “unembarrassed penchant for reproduction.” Francis Mah, MD
Some bugs create a whole new generation every twenty minutes
The antibiotic era: Began 1928 when Alexander Fleming discovered penicillin
Used for World War II; general use late 1940s
Is this the beginning of the end of the antibiotic era?
“The bugs are getting stronger-and they’re getting stronger faster” Barry Kreiswirth
Ten years ago: Nearly all strains of Streptococcus pneumoniae were susceptible to penicillin.
Today: 45% of all strains are resistant.
Infrastructure: Animals and agriculture
Five times as many domestic food animals as people in the United States
Daily animal fecal excretion can be 5-400 times greater than humans
Amount of feces excreted by a cow per day is 100 times more than a human
Flies carry genetically exact antibiotic-resistant organisms from nearby animals.
Ground water and streams contaminated with antibiotic-resistant bacteria
Used to treat fruit trees, honeybees hives, and catfish and salmon farms.
The arms race
“The war between humans and bacteria seems like a hopeless one because of the sheer
numbers of bacteria, their incredible ability to adapt, and their unembarrassed penchant for
reproduction.” Francis Mah, MD
Pharmaceutical researcher’s chess game:
Bacteria try to checkmate the best antibiotic move, the new antibiotic molecule attempts at
checkmating the new bacterial strain
Defenses
Some succeeded in making cell walls impermeable
Others created tiny pumps that vomited antibiotics out of the cell (efflux pump)
Some have developed enzymes to attack the antibiotic and slice chemical rings
Some antibiotics target an enzyme for attachment; bacteria have changed or replaced those
enzymes
Strict guidelines needed
Correct dosing in specific and selected and properly diagnosed infections
Correct period or duration of time
Carefully selected patients
The drugs: fluoroquinolones
3G fluorquinolones: Ciprofloxacin (Ciloxan) 5ml $40.99; Ofloxacin (Ocuflox) 5ml $40.99
3G 4G fluorquinolones: Levofloxacin (Quixin); New formulation 1.5% levofloxacin
4G fluorquinolones: Moxifloxacin (Vigamox)(oral: Avelox 1999), Gatifloxacin (Zymar)(oral:
Tequin 1999)
Reduced dosing: 140 patients with confirmed bacterial conjunctivitis
Treated topically BID for 3 days
Results: 81% were classified as microbiological successes.
Bacterial keratitis
300 cases over 20 month period
Risk factors found: Contact-lens wear 50.3% History of keratopathy 21% Trauma 15%
Case report: Contact lens related infection
History: 34 year-old female wanting SCL. In the past she reports a “red eye” with extended
wear contact lens wear.
Slit lamp evaluation: Inferior superficial punctate keratitis in both eyes, more dense in the
right eye. Closer examination of the blink showed an incomplete blink.
Diagnosis: Infiltrative keratitis and dryness
Treatment: Use a steroid in combination (Tobradex)?
Use an Antibiogram
4G fluorquinolone resistance
Ask patient about hospital based infections and treatments.
“There will be a continual need for new antibiotics because bacteria are very adaptable. We’ve
already seen some resistance to fourth-generation fluoroquinolones in some ocular isolates,
mainly because they have been in the systemic world for years”
“Typically antibiotics have a 7 to 10 year lifespan. We hope with the proper use this will be
the case with the fourth-generation fluoroquinolones as well.”
Deepinder K. Dhaliwal, MD
The future: 5G fluorquinolones: Trofloxacin (oral: Trovan), Azithromycin, Linezolid