|Year : 2012 | Volume
| Issue : 4 | Page : 483-485
Comparative in vitro evaluation of activity of tigecycline against susceptible and multidrug resistant organisms
V Gupta, N Bansal, J Chander
Department of Microbiology, Government Medical College Hospital,Sector 32-B, Chandigarh, India
|Date of Submission||17-Apr-2012|
|Date of Acceptance||01-Jul-2012|
|Date of Web Publication||24-Nov-2012|
Department of Microbiology, Government Medical College Hospital,Sector 32-B, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gupta V, Bansal N, Chander J. Comparative in vitro evaluation of activity of tigecycline against susceptible and multidrug resistant organisms. Indian J Med Microbiol 2012;30:483-5
|How to cite this URL:|
Gupta V, Bansal N, Chander J. Comparative in vitro evaluation of activity of tigecycline against susceptible and multidrug resistant organisms. Indian J Med Microbiol [serial online] 2012 [cited 2020 May 29];30:483-5. Available from: http://www.ijmm.org/text.asp?2012/30/4/483/103784
The incidence of infections due to multidrug resistant organisms has increased worldwide in recent years in both outpatients as well as hospitalized patients. It varies according to geographic locales and is directly proportional to the use and misuse of antibiotics. There is a pressing need for new antibiotics to combat the worsening problem of bacterial resistance to existing agents. Tigecycline is the first in a new generation of tetracyclines known as glycylcyclines, approved by the US Food and Drug Administration (FDA) for the treatment of complicated intra-abdominal and complicated skin and soft tissue infections in June 2005. The properties of tigecycline confer in vitro activity against a wide range of bacterial pathogens, including Gram-positive and Gram-negative aerobic and anaerobic species.  Keeping this in mind, we planned a comparative study to evaluate activity of tigecycline against susceptible and multidrug resistant strains of both Gram-positive cocci as well as Gram-negative bacilli in tertiary care hospital setting from India.
The study was conducted in the Department of Microbiology, Government Medical College Hospital, Chandigarh on three groups of isolates. Group I : m0 ethicillin susceptible Staphylococcus aureus(MSSA, n=25) vs. methicillin resistant S. aureus(MRSA, n=25); Group II : e0 xtended spectrum beta lactamases (ESBL) negative (n=25) vs. ESBL positive (n=25) Enterobacteriaceae; and Group III : C0 arbapenem sensitive (n=25) vs. carbapenem resistant (n=25) Acinetobacter calcoaceticus-baumannii complex. The isolates collected were consecutive, non-duplicate and were derived from various clinical samples including blood, pus and wound swabs, tracheal aspirates and urine during the period of four months from March'2011 to June'2011. Organisms were identified as per standard protocols and antibiotic sensitivity for methicillin resistance in Staphylococci, ESBL detection in Enterobacteriaceae and carbapenem resistance in Acinetobacter cbc was done by disc diffusion methodology as per Clinical Laboratory Standards Institute (CLSI) 2010 guidelines.  Minimum inhibitory concentration (MIC) to tigecycline was determined using E-test gradient strips (BioMerieux, S.A., France) with a concentration range of 0.016 to 256 μg/ml on Mueller-Hinton agar plates. The MIC 50 and MIC 90 for each of the comparable groups were noted and statistical analysis was done using unpaired t-test and P value<0.05 was considered statistically significant.
The results of the study are depicted in [Table 1]. Considerable in vitro activity of tigecycline has been observed against MSSA and MRSA, as well as ESBL negative and ESBL positive isolates of Enterobacteriaceae. However, significant difference was noticed in the MICs of comparable isolates in Group III (P<0.05) i.e. carbapenem sensitive Acinetobacter cbc (MIC range 0.032 to 1 μg/ml) compared to carbapenem resistant Acinetobacter cbc (MIC range 0.064 to 16 μg/ml).
|Table 1: In vitro activity of tigecycline against susceptible and multidrug resistant organisms|
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Tigecycline offers a great promise as a new therapeutic agent for serious infections caused by multidrug resistant (MDR) pathogens. It is found to be highly effective in vitro against both nosocomial and community-acquired methicillin-susceptible or-resistant S. aureus strains, susceptible and multidrug resistant Enterobacteriaceae similar to our results ,, while efficacy reports against MDR Acinetobacter cbc are not universally consistent. ,, The potential development of resistance to tigecycline during the course of therapy is worrisome. Moreover, there is paucity of available supporting clinical data regarding the efficacy of tigecycline for the treatment of patients with infections caused by carbapenem resistant Acinetobacter cbc; also being confounded by its use in combination regimens in routine clinical practice. Thus, we conclude that in vitro studies favor the use of tigecycline in MDR S. aureus and Gram negative bacteria but further studies are warranted to establish role of tigecycline in clinical practice as a therapeutic option for infections caused by multidrug resistant Acinetobacter cbc.
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