Evaluation of tigecycline activity in clinical isolates among Indian medical centers.
BACKGROUND
Resistance to multiple antibiotics among Gram-positive cocci (GPC) and Gram negative bacilli (GNB) is high in India. Tigecycline, a glycylcycline antibiotic is a newer treatment option for emerging single or multidrug-resistant (MDR) GPC and GNB.


METHODS
We evaluated the in vitro activity of tigecycline and compared it against other antimicrobials. Between 2005-2007, seven Indian medical centers from diverse geographic regions forwarded 727 isolates [Escherichia coli (166), Staphylococcus aureus (125), Klebsiella spp (120), Streptococcus pneumoniae (102), Enterococcus spp. (100), Pseudomonas aeruginosa (50), Acinetobacter spp. (50) and Enterobacter spp. (14)] from patients with blood stream (BSI), skin and soft tissue (SSTI) including surgical site, urinary tract and respiratory infections to our reference laboratory. Susceptibility to 11 antimicrobials besides tigecycline included: vancomycin, linezolid, teicoplanin, quinopristin-dalfopristin, daptomycin, amikacin, imipenem, levofloxacin, meropenem, and piperacillin/tazobactam was determined by agar dilution and Etest method.


RESULTS
Tigecycline was active against all GPC (MIC 90 < 0.25 μg/ml), E. coli and Klebsiella spp. (MIC 90 ≤1 μg/ml). MDR Acinetobacter spp. showed lower susceptibility (70.6%) to tigecycline. Tigecycline MIC 90 values were not influenced by oxacillin resistance among S. aureus, S. pneumoniae, vancomycin resistance in Enterococci (VRE) and ESBL producing E. coli, Klebsiella spp. and Enterobacter spp. Increased resistance was seen to other antimicrobials among ESBL producing E. coli, Klebsiella spp., Metallo Beta Lactamase (MBL) producing P. aeruginosa and VRE.


CONCLUSIONS
Tigecycline is an alternative option for emerging multidrug-resistant (MDR) pathogens exhibiting promising spectrum/potency exceeding currently available agents seen in India.
Benjamin M Pulimood Laboratories for Infection, Immunity and Inflammation (BMPLIII), Department of Medicine Unit I and Infectious Disease, Christian Medical College, Vellore-632 004, Tamil Nadu, India. anandm@cmcvellore.ac.in
Anand
A
Manoharan
Saradiya
S
Chatterjee
S
S
Madhan
Dilip
D
Mathai
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D001424:Bacterial Infections / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D006761:Hospitals; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D000078304:Tigecycline
D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline