Superbug,few drugs: Acinetobacter antimicrobial resistance in India

Background

Acinetobacter baumanii is a gram negative, aerobic coccobacillus which has gained increasing importance in current times particularly in hospital settings. Institutional outbreaks by multidrug resistant Acinetobacter baumanii is a growing concern.

Acinetobacter baumanii is associated with healthcare related infections such as pneumonia, meningitis, urinary tract infections and wound infection. Multi drug resistant Acinetobacter deep wound infections, osteomyelitis and respiratory infections has been reported among military personnel in Iraq and Afghanistan conflicts.

In India, estimation of disease burden and its status of antimicrobial resistance need to be assessed. In this analysis conducted on diagnostic labs-based culture and sensitivity data, sensitivity of Acinetobacter was analysed against commonly indicated antimicrobial agents. Study includes all samples positive for Acinetobacter baumanii, which includes blood, pus, sputum, stool and urine. Overall sample size for the study was 1284 with biggest share of urine samples (44.2%) followed by sputum as 27.3%.

Therapeutic options for Acinetobacter baumanii includes sulbactam, carbapenems (Imipenem, Meropenem and Doripenem), aminoglycosides (Amikacin, Tobramycin), polymyxin B and Colistin. We analysed sensitivity status of Acinetobacter baumanii against fluoroquinolones, aminoglycosides, carbapenems, penicillins, Tigecycline, Nitrofurantoin, Fosfomycin, Cotrimoxazole, piperacillin, nalidixic acid and trimethoprim.

STUDY: Results and discussion

Acinetobacter baumanii was found to be most sensitive for gatifloxacin (99%) and colistin (95.9%). Other antimicrobial agents which has good coverage (>75%) were tigecycline, minocycline, fosfomycin, doxycycline and ofloxacin.

Among carbapenems, Doripenem has highest coverage (~70%) followed by meropenem and imipenem (~55%). Acinetobacter has shown almost complete resistant to ertapenem and faropenem.

Ampicillin-sulbactam has surprisingly very low coverage (18.2%) though it is first line choice as indicated by many studies. Acinetobacter was found to be most sensitive for cefepime (56%) among cephalosporins while third generation cephalosporins (ceftriaxone, ceftazidime, cefuroxime ) have less than 33% coverage.

Among tetracyclines, minocycline and doxycycline have very high coverage (~80%). Aminoglycoside (Amikacin, gentamicin and tobramycin) have modest efficacy (46-62%).

Among fluoroquinolones, Acinetobacter was found to be most sensitive for gatifloxacin (99%) followed by ofloxacin (75%). For other fluoroquinolones (Ciprofloxacin, levofloxacin, pefloxacin) sensitivity was less than 60%. Nitrofurantoin has only 3% of samples sensitive to it. Amoxiclav, aztreonam also shown very poor coverage (<20%). Cotrimoxazole has sensitivity close to 50%.

Multidrug resistance in Acinetobacter baumanii

?There were 92 samples tested for 19 different antimicrobial agents namely amoxicillin, amoxicillin-clavulanic acid, cefixime, Cefoperazone-sulbactam, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, levofloxacin, colistin, ertapenem, imipenem, gentamicin, meropenem, nitrofurantoin, piperacillin-tazobactam, norfloxacin and cotrimoxazole. Ninety (97.8%) out of 92 were resistant to 3 or more drugs. Seventy-eight (84.8%) out of 92 were resistant to 11 or more antimicrobial agents. 29 samples (31.5%) were resistant to 18 out of 19 antimicrobial agents and only showed sensitivity to colistin. 

To conclude….

Acinetobacter is an emerging public health issue in context of antimicrobial resistance and a close surveillance is warranted to understand its patterns and to take timely steps to control it.