Hello Krishna, I am not sure what you mean by antibiotics in your situation. But what are I know, there are many antimicrobials available and with different range of spectrum of micro-organisms they can kill/slow their growth. The fact that some antimicrobials work synergistically, it might me one of the reasons why people choose to combine antimicrobials. Additionally, if you want to achieve slow release of antimicrobials by using a smaller dosage then reverting to a maintenance dosage is all part of clinical decision you make as a clinician. Kind regards.

Dr Moono, for example in a patient with a drained abscess in the extremity, which of the following is acceptable

the combination of oral cloxacillin + iv Gentamicin

oral teracyclin + iv cefotaxime

oral erythromycin + iv Amikacin

Dear Krishna

Oral administration : the majority of patients with infections are treated with oral antibiotics . The advantages of the oral route are lower cost , fewer side effects and greater patient acceptance . The rate of absorption of an orally administered antibiotic varies between 20% (e.g. , erythromycin ) and almost 100% (in the case of amoxicillin , clindamycin, linezolid , ... ) . These differences in bioavailability is not clinically important since the drug concentration at the site of infection is sufficient to inhibit or eliminate the causative agent of the infection.

However the effectiveness of therapy can be compromised when the absorption is reduced as a result of physiological or pathological conditions ( such as the presence of food in the stomach or the existence of a diarrhea ) , drug interactions , or for noncompliance with therapy.

The oral route is usually used for patients with infections of low grade of severity and its absorption is not affected by any condition.

Intravenous administration : intravenous route is indicated when oral antibiotics are not effective against a pathogen particularly when bioavailability is uncertain when large doses are required and when an immediate effect is required

The simultaneous use of the two routes of administration must meet specific criteria

Please download a app absn antibiotics for treatment guidelines for common infections developed by us for use in India

Please be aware that there is a lot of interactions possible when the drugs are used together. Eg Ciprofloxacin should not be used with multivitamins containing divalent and trivalent cations like Calcium and magnesium. Almost 50% of cipro will be chelated if multivitamins are given together with it.

In my opinion an oral antibiotic could not be combined with an intravenous antibiotic . In case of severe life-threatening infection -orbital cellulitis combination of two IV is used Cefazolin for G+ and Ceftriaxone for G- organisms coverage

In severe sepsis, antimicrobial therapy should be started in the hour after the diagnosis, at least full dose or at 7_8 mg/kg for Gentamicin or Tobramycin, whatever the kidney function, but few hours after, in absence of a supposed oral compromised absorption, the combination of IV aminoglycosides and oral betalactamines or fluoroquinolones ( FQ) could be proposed, for urinary sepsis for instance ( the second main disease requiring hospital admission). Oral FQ bioavalibity being perfect and ten times cheaper than IV administration.

Thus oral and IV combination is safe and warranted, in contrast with “slow release and smaller dosages” which should be avoided, in few of their higher mortality rate..

Why not?! It depends on the pharmacologic profile of the antibiotics. Gyrase-Inhibitors have the same serumlevel if taken by mouth or given intravenously. Why not combine in some septic patients these antibiotics with others only available for intravenous use?

can we use oral and IV antibiotics in neonatal sepsis, definitely no