its about how to choose an antibiotic with a rationale

1. Rational use of antibiotics
Dr Smarajit Patnaik
Senior Consultant Orthopaedics and Adult reconstruction
Surgeon
Apollo Hospitals Bhubaneshwar,Odisha.

2. Rationalizing the use of antibiotics is an important
patient safety and public health issue in addition to
being a national priority

3. • Use of antibiotics in orthopaedic surgery has an important
role in treatment of osteo-articular infections along with
surgical treatment.
• Antibiotics also have an important role for prophylactic
administration in orthopaedic surgeries involving implants
and prosthesis and in deep surgical wounds.

4. The characteristics of the implant material are also
very important for the development of infection
Titanium, which is more biocompatible, is colonized by tissue cells
faster and therefore protected from bacteria colonisation when
compared with CrCo and CrCo is better protected compared to SS
The tissue cells win the “race for the surface” more easily on titanium
Bacteria win “the race for the surface” more easily on porous surfaces
and quickly form colonies covered by glycocalyx
In the race for the surface: Titanium with smooth surface is
the winner

5. Bacterial adherence on biomaterials with
antibiotics
PMMA with gentamycin requires the
inoculation of 60 times more
Staphyloccocus aureus than PMMA
without antibiotic to become infected.

6. Antibiotic prophylaxis
Antibiotic prophylaxis is justified at every surgery involving
an implant, because it reduces the rate of infection from 5% to
1%.
Antibiotics can eliminate bacteria before they colonize
implants or are established intracellularly in the macrophages
The lowest rates of infection are obtained by the combination
of intravenous antibiotics and the use of antibiotic-loaded
cement.

7. The Real reasons for irrational antibiotic
usage: are we the only ones to be blamed!
Very short consultation time - does not allow proper diagnosis
Polypharmacy - Too many medicines are prescribed per patient (Lack of trust in or delayed lab results, fear of clinical failure)
Patients self-medicate inappropriately
Patients do not adhere to prescribed treatment
Prescription of antibiotics for non-bacterial infections
Antibiotic injections are used where oral formulations would be more appropriate
Prolonged prophylactic therapy
Prolonged empiric antimicrobial treatment without clear evidence of infection
Failure to narrow antimicrobial therapy when a causative organism is identified
Prescriptions do not follow clinical guidelines

8. Council for Appropriate and Rational Antibiotic
Therapy (CARAT) criteria:

9. While choosing the right antibiotic,
Consider :
relevant host factors,
pathogen-related factors,
drug-related factors.
The “Rule of Right” – right medicine in the right manner
(dose, route, frequency, and duration of administration) in
the right patient at right cost – must be followed while
using antibiotics

10. Important host-related factors
Age and immune status of patient, local
factors like pH, presence of pus or blood,
presence of foreign body or obstruction,
history of allergies, pregnancy and
lactation, presence of other diseases, and
severity of infection under treatment.

11. While considering organism-related factors,
it should be decided whether the
organism causing infection is community
acquired or hospital acquired.
“Best guess” method can be applied for
empirical therapy. (Educated Guess)
Results from analysis of antibiograms in
local hospital is of great importance.

12. Drug-related factors:
include consideration where the drug
being chosen is bacteriostatic or
bactericidal,
pharmacokinetic profile of drug, its
possible adverse effects, and the cost of
therapy

13. OSTEOMYELITIS
Introduction
Osteomyelitis is an infection of the bone.
Osteomyelitis is characterized by sequestra formation.
Classification
Based on the duration of illness –
Acute osteomyelitis (days-weeks) Absence of sequestra
Chronic osteomyelitis (months-years) Presence of
sequestra&/or sinus tract
Based on the mechanism of infection
Contiguous e.g Trauma, soft tissue infection, decubitus ulcer
Hematogenous– Most often affects long bones and vertebral
bones
Vascular insufficiency e.g Diabetes mellitus
Based on anatomical stage and host factors -Cierny-Mader
staging system

14. Common organisms causing
osteomyelitis
Hematogenous osteomyelitis is usually
monobacterial, Contiguous osteomyelitis
may be polymicrobial.
Staphylococcus aureus, Enterobacter
species, Streptococcus species,
Pseudomonas species, gram negative
bacilli.

15. Cultures:
Preferable to collect specimen prior to initiation of therapy and only from wounds that are clinically
infected. In case the patient is currently on antibiotics which appear to be ineffective it is advisable to
discontinue for 1-2 weeks if possible.
Use standard techniques to collect sample.
Swab cultures and sinus tract cultures may be unreliable
Container: Sterile screw-capped container / sterile swabs in the screw capped tubes
A swab from wounds: (generally discouraged as they often grow skin colonizers)
-Collect swabs only when tissue or aspirate cannot be obtained.
-Sinus tract
Samples should be collected using a syringe and needle.
It should be placed in a sterile container.
A portion of the sample should also be placed in a sterile tube containing
anaerobic medium like if an anaerobic culture is required.
-Blood culture
Blood culture should be obtained along with wound and bone culture for all patients presenting
with acute Osteomyelitis.

16. Approach to management

17. Septic arthritis of native joint
Infection of native joint is most often due to bacteremia,
occasionally can also result due to direct injury to joint e.g
Trauma, therapeutic joint injections.
Most common bacteria causing septic arthritis are gram
positive, Staphylococcus aureus being the commonest. gram
negative septic arthritis is seen in the setting of
gastrointestinal or urogenital bacteremia.
Risk factors

18. Prosthetic joint infection (PJI)
Prosthetic joint infection is the worst complication of joint
replacement surgeries.
Presence of biofilm on prosthesis makes diagnosis and treatment
of prosthetic joint infections very challenging.
PJI is present when one of the following criteria is present:
Sinus tract communicating with a prosthesis
Presence of pus
Acute inflammation on histopathologic evaluation of periprosthetic
tissue
Two or more positive cultures with the same organism
(intraoperatively and/or preoperatively)
Single positive culture with the virulent organism.

19. PJI
Common organism:
• Staphylococcus aureus- common in western literature
• Coagulase-negative Staphylococci common in western
literature
• Enterococci
• Gram negative aerobic bacilli quite common in the Indian
setting
• Propionibacterium acnes for shoulder

20. Intraoperatively
At least 3 and optimally 5-6 samples of periprosthetic tissue must be
obtained for:
a. Histopathology of periprosthetic tissue.
b. Periprosthetic tissue/pus culture.
c. Sonication of the prosthetic implant will detect biofilm organisms &improve
microbiological yield especially in patients with prior receipt of antimicrobials
.
Molecular methods and synovial fluid biomarkers are newer diagnostic
modalities for culture negative PJI.

21. Biofilms
The most important consideration in the management of bone & joint
infections is the presence of biofilm associated with implants and
prosthesis. The implications of biofilm formation are:
Antibiotic penetration into biofilm is poor
Antibiotics that penetrate may not act on biofilm organisms (non-
replicating, stationary phase)
Biofilm organisms are protected from immune processes like
phagocytosis
Biofilm organisms can acquire resistance patterns from one another

22. Antimicrobial regimen used to treat B&J
infection
– Bactericidal drugs are preferred for deep seated infections
e.g. osteomyelitis
– Agents with good bone penetration
– Drugs with biofilm activity (penetration into biofilm, action
against biofilm organisms)
– Least toxic and most affordable regimen should be used in
view of prolonged duration of treatment
• The use of local antibiotic cement spacer/antibiotic
impregnated beads is a useful adjunctive treatment option
along with systemic antibiotics, especially in drug
resistant, difficult to treat B&J infections

23. Likely organisms after implant surgery/PJI
based on interval between Sx and infection

24. Choice of empiric antibiotics for B&J infection

25. Approach to PJI and Implant related infection

26. Pathogen specific antibiotics

27. *Parenteral antibiotics are generally
recommended for at least the 1st 2 weeks,
may step down to oral antibiotics with
good bioavailability if susceptible to
complete the course of treatment
** Antibiotic-impregnated cement
spacers/beads must be considered in
addition to systemic antibiotics especially
in resistant infections with few drug
options/ drugs which have poor B&J
penetration/ drug toxicity.

28. Oral Antibiotic Options for Treatment

29. Aetiology based on host and environment

30. Standard doses of antimicrobial agents

31. Surgical Stewardship
• Evaluate the infection by clinical
diagnosis: Key is to spend time
• Select an appropriate antibiotic
therapy regimen:
Definitive therapy or an Empirical
therapy or a Prophylactic therapy.
• Criteria for choosing an antibiotic
drug: narrow spectrum antibiotic
which is cost-effective and least toxic
for the shortest duration possible.
• Definitive therapy: When
the etiology of the infection
is known
• Empirical therapy: critical
patients , clinicians
working knowledge or
experience of what is most
likely to be the pathogen,
broad spectrum antibiotics
• Prophylactic therapy: pre-
surgical patients,
immunocompromised
patients and patients with
traumatic injuries.

32. Efficacy of my treatment; I am most worried about
Narrow spectrum( Prophylaxis) or Broad spectrum(Life
threatening)
Monotherapy or combination therapy
• To achieve synergistic effect against the infection,
• Combination therapy also shortens the course of antibiotic
therapy
• Hospital- associated infections
• To extend antibiotic spectrum during polymicrobial infections
• To prevent the development of bacterial resistance with long
term therapy
Efficacy at the site of infection & tissue penetration
Bactericidal vs bacteriostatic therapy

33. The need for an antimicrobial therapy should be reviewed
on a daily basis by reviewing laboratory evidence.

34. ANTIBIOTIC RESISTANCE
What doesn’t kill you, only makes you stronger

35. “Rule of Right”
• The “Rule of Right” – right medicine in
the right manner (dose, route,
frequency, and duration of
administration) in the right patient at
right cost – must be followed while
using antibiotics

36. “7D’s of optimal antibiotic therapy:
• Right Drug,
• Right Dose,
• Appropriate Direction (route of
administration),
• De-escalation to pathogen- directed therapy,
and
• Right Duration of therapy,
• Watch for and consider Drug to drug
interaction,
• Always evaluate for possible immune
Deficiency to optimize antibiotic use in clinical
settings.

37. Summary algorithm for rational prescription of antibiotic therapy

38. A judicious use of antibiotics means;
Prudent use of available antibacterial
agents,
take precautions for the control of
cross-transmission of resistant strains,
isolate carriers patients, obtain
accurate diagnosis,
Antibiotics should only be prescribed
when they are required and we must
conduct more research to development
antibiotics with a novel mechanism.
Antibiotics must be
administered in proper
dose with proper
interval and using the
narrowest spectrum
and shortest duration
of therapy, and
switching to oral
agents as soon as
possible.

39. Conclusion
• Antibiotic prophylaxis should be made
considering the specific germs of each
hospital and their antibiotic sensitivity.
• The antibiotic treatment is not effective
as long as the source of infection
(infected implant, bone sequestrum) is
not surgically removed.
• Irrational use of antibiotics has resulted
in the rise of multi-drug resistant
bacteria- the so called “superbugs”.

40. THEY DON’T LIVE IN OUR WORLD ….
WE LIVE IN THEIR WORLD !!
The human body, which contains about 1013 cells, routinely
harbours about 1014 bacteria called as normal microbial
flora.