1.ROLE OF ANTIBIOTICS IN ORTHOPEDIC INFECTIONS
By Dr. MohdViquasuddinSaim
MS(ortho),PIMS

2. osteomyelitis
An infection of bone most commonly caused by pyogenic bacteria and mcyobacteria.
Types
Hematogenousosteomyelitis
Osteomyelitis secondary to contiguous focus of infection
Chronic osteomyelitis
3. Microbiology of hematogenousosteomyelitis
Majority of cases occur in children
95% of cases of hematogenousosteomyelitis are caused by a single organism.
Staph.aures accounts for 50% of cases.
Other common pathogens are group A streptococci in children, group B streptococci and E.coli in neonates.
4. Microbiology of hematogenousosteomyelitis
In adults, hematogenousosteomyelitis occurs most commonly in vertebrae.
The organisms are staph.aureus, pseudomonas, serratia and candida.
The most common risk factor is iv drug abuse
Hemoglobionopathy patients have osteomyelitis of long bones caused by salmonella and staph.aureus.
5. Microbiology of hematogenousosteomyelitis
Immunocompromised persons may develop osteomyelitis due to atypical mycobacteria, bartonella and fungi.
6. Microbiology of contiguous focus osteomyelitis
Staph.aureus accounts for >50% cases.
However, these infections are mostly polymicrobial and involve anaerobes and gram negative bacteria.
Staph.aureus most common cause of post operative osteomyelitis.
Coagulase negative staph are common pathogens after implantation of orthopaedic appliances.
7. Microbiology of contiguous focus osteomyelitis
Mycoplasma can cause sternalosteomyelitis after cardiac surgery.
Pseudomonas can cause osteomyelitis after puncture wounds of foot.
Pasteurella.multocidaosteomyelitis follows cat bite.
8. Principles of Antibiotic therapy in osteomyelitis
Antibiotics should be administered only after appropriate specimens have been obtained for culture.
use of bactericidal antibiotics is recommended.
Antibiotics should be given in high dose parentrally.
9. Principles of Antibiotic therapy in osteomyelitis
Guidelines for empirical therapy:
It should be chosen based on findings on gram staining of a specimen from a bone or abscess.
Or it can be chosen to cover the most likely pathogens.(staph.aureus)
Empirical antibiotic therapy should also include against anaerobes in the setting of decubitis ulcer and diabetic foot.
10. Principles of Antibiotic therapy in osteomyelitis
Specific therapy:
Its ultimately based on in-vitro susceptibility testing of organisms isolated from bone or blood.
The decision to give outpatient parenteral antimicrobial therapy is suitable for medically stable and motivated patients.
Parenteral therapy should be given for 5-10 days and then oral antibiotics should be used.
11. SUGGESTED REGIMENS
For Staph aureus
Penicillin resistant, methicillin sensitive : Nafcillin / Oxacillin 2gm IV q4h
Penicillin sensitive : Penicillin 3-4 million U IV q4h
Methicillin resistant : Vancomycin 15mg/kg IV Q12h + Rifampicin 300mg PO q12h
Penicillin allergic patients : Clindamycin 900mg IV q8h / Cefazolin 1g IV q8h.
12. SUGGESTED REGIMENS
Streptococci : d.o.c Penicillin. Alternatives: cefazolin, clindamycin.
Gram negative bacilli : E.coli : d.o.c : Ampicillin 2g IV q4h , alternative : CeftriaxonePseudomonas : d.o.c : Piperacillin 3-4g IV / Ceftazidime 2g IV plus Tobramycin 5-7mg/kg
Mixed infections : Ampicillin+sulbactam, Piperacillin+tazobactamalternative : Carbapenem+Clindamycin.
13. Septic arthritis
Microbiology
Every bacterial pathogen is capable of causing septic arthritis
In infants : group B Streptococci, gram negative bacilli and staph aureus.
Adolescents and young adults : neisseria gonorrhea is most common
Staph aureus most common non gonoccocal cause
14. Septic arthritis
Microbiology
Infections after surgical procedures and penetrating injuries are caused by staph aureus
Human bites near joints and extension of decubitus ulcers cause septic arthritis due to anaerobes
Bites and scratches from cats introduce pasteurella into joints.
15. Septic arthritis
Rx
Prompt administration of systemic antibiotics and drainage of involved joint is needed.
Emperical antibiotics should be started once samples of blood and synovial fluid have been obtained for culture.
Emperical antibiotics are given based on bacteria visualised on smears
16. Septic arthritis
Initial therapy should consist of iv adminsitration of bactericidal agents
Direct administration of antibiotics into joints is not necessary
D.o.c: iv cefotaxime or ceftriaxone if smears show no organisms
Is smears show gram positive cocci : oxacillin or naficillin is used
If MRSA : Vancomycin
17. Septic arthritis
Definitive therapy is based on identity and antibiotic susceptibilty of bacteria isolated in culture
For staph : oxacillin/ naficillin or vancomycin
For pneumococcal and strepto :2 weeks of penicillin
For H. Influenzae : cefotaxime
Enteric gram negative infections : ceftriaxone or fluroquinolone for 3-4 weeks
18. Gonococcal arthritis
Initial treatment iv ceftriaxone 1gm
Once local and systemic signs resolve 7 day course of ciprofloaxcin can be given
19. Infections in prosthetic joints
Rx
High dose parenteral antibiotics for 4-6 weeks because bone is involved.
A high cure rate with retention of prosthesis has been reported with the combination of oral rifampicin and ciprofloxacin for 3-6 months
20. Role of antibiotics in gas gangrene
Previously the antibiotic of choice has been PenicillinG , 20 MILLION UNITS per day.
But due to increasing resistance to this drug, antibiotics inhibiting toxin synthesis appear to be favourable.
Clindamycin treatment enhanced survival than penicillin treatment
Dose of clindamycin : 600mg every 6h.
21. Anti TBdrugs
First line essential drugs
1. Rifampicin : most important and most potent
2. Isoniazid : 2nd best anti TB drug available
3. ethambutol : least potent amongst first line drugs
4. Pyrazinamide : important in short course therapy
22. Anti TB drugs
First line supplemental drugs
1. streptomycin : available for iv/ im administration only
2. rifabutin : recommended in HIV positive individuals in place of rifampicin
23. Anti TB drugs
Second line drugs
1. Quinolones : Levofloxacin and Moxifloxacin
2. Capreomycin
3. Amikacin
4. Ethionamide
5. Para-aminosalicylic acid
6. Cycloserine
24. Newer anti TB drugs
LINEZOLID : can be used in drug resistant TB cases
Can be used iv or orally
25. Anti TB drug regimens
Category I includes : spinal disease with neurological complications.
The treatment in Category I consists of an intensive phase of isoniazid (H), rifampicin (R), Pyraziamide (Z) and ethambutol (E) administered under a direct supervision thrice weekly on alternate days for 2 months (24 dosages), followed by a continuation phase of H and R thrice weekly on alternate days for 4 months (18 weeks, 54dosages).
The first dose of each week given directly supervised and the patient self-administering next two doses of the week, at home.
26. Anti TB drug regimens
Category III: includes sputum negative musculo-skeletal TB
Category III treatment is similar to that of Category I, but is executed without an inclusion of ethambutol.
27. Anti TB drug regimens
Category II :
Relapsed and treatment failure (smear-positive) cases
Treatment after substantial interruption.
These patients are at risk of developing multidrug resistant tuberculosis (MDR-TB)
In category II intensive phase consists streptomycin (S), H, R, Z and E for 2 months followed by 1 month of H, R, Z and E (total 36 dosages), is administered in the same supervised manner as Category I and is followed by an appropriately supervised continuation phase consisting of 5 months (22 weeks, 66 dosages) of H, R and E.
28. Side effects of anti TB drugs
Rifampicin : GI upset, hepatitis, rash, flu like syndrome and red orange urine.
Isoniazid:hepatitis, peripheral neuropathy and seizures.
Pyrazinamide : hepatitis, hyperuricemia and arthralgia
Ethambutol : optic neuritis
Streptomycin, amikacin and capreomycin : ototoxicity and nephrotoxicity
29. Side effects of other antibiotics
Beta lactams : allergies in 1-4 % patients, diarrhea, non allergic skin reactions.
Vancomycin : red man syndrome, nephrotoxicity and ototoxicity
Aminoglycosides : nephrotoxicity (reversible) ,ototoxicity (irreversible)
Clindamycin : diarrhea due to colitis
Fluoroquinolones : tendon ruptures
30. Side effects of other antibiotics
Metronidazole : metallic taste
Linezolid : thrombocytopenia and peripheral neuropathy.
31. Thank you
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