Stenotrophomonas spp are known to be intrinsically resistant to many antibiotics (Brooke, 2012). Stenotrophomonas maltophilia have been associated with.
Susceptibility pattern of Stenotrophomonas spp to Antibiotics Elufisan Temidayo Oluyomi1, Isabel Cristina Luna Rodriguez1, Omotayo Opemipo Oyedara1, Miguel Angel Villalobos2 and Xianwu Guo1 1Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Reynosa, Tamaulipas 88710, México 2Center of Applied Biotechnology Research Instituto Politécnico
Introduction Microbial resistance to anti-microbial agent is a big threat to health care delivery. Stenotrophomonas spp are known to be intrinsically resistant to many antibiotics (Brooke, 2012). Stenotrophomonas maltophilia have been associated with various form of infection in immunocompromised individual with underlying diseases such as Cancer, keratitis and even in Septicemia (Safdar and Roston, 2017). Stenotrophomonas has remained criminals in health sector because of their ability to resist a wide range of antimicrobial agents and quickly develop resistance to new ones.. It is therefore necessary that study on the surveillance of S. maltophilia resistant pattern to antimicrobial agents are continuous. In this study we evaluated the susceptibility pattern of Stenotrophomonas species isolated from the environment with a view towards understanding their tendency to develop resistance to antimicrobial agents due to environmental selective pressures.
Methodology
Table1: Biochemical characteristics of isolates
Stenotrophomonas spp were isolated using double agar layer plating technique and Stenotrophomonas selective medium. Biochemical characterization was carried out using conventional laboratory technique as per Berges’ Manual of Microbiology. Molecular identification was done by amplifying the 16S ribosomal DNA of Isolate and sequencing of the amplified fragment. Antibiotic susceptibility study was carried out using Kirby Bauer's disc diffusion method technique and MIC testing. The result was interpreted according to CLSI standard. The evaluation of biofilm formation in Isolates was evaluated as described by O Toole, 2011. The molecular basis of resistance was evaluated by amplifying the beta lactamase gene with three pair of primers which are capable of amplifying blaTem blaSHV and blaNDM-1 and two other primer sets which amplified for the presence of tetA and tet B genes
Result Forty-three Isolates were obtained from soil and sewage samples and identified to be Stenotrophomonas spp following biochemical (Table1) and molecular identification. The sequence of some the isolates have been deposited on NCBI database. We noted multiple drug resistance behavior in all isolates with each resisting more than three out of the antibiotics tested (Fig1 and Table2). Biofilm formation were found in in most of the isolates and the level of formation corresponds with observed resistance in bacteria (Fig2). The result obtained from the evaluation of the molecular basis for resistance in isolates showed that the presence of one or more resistant gene(s) is/are responsible for the observed resistance.
Conclusion
Fig1: Stenotrophomonas susceptibility pattern to isolates
High level of resistance was observed in all isolates. Isolates were obtained from the environment and thus the level of intrinsic resistance should be a major concern. An important observation from this study is the observed resistance to cotrimoxazole. About 76% of the isolates were resistant to cotrimoxazole. Cotrimoxazole is the first line of drug for the treatment of Stenotrophomonas infection, however the observation in this study may suggest it ineffectiveness if applied. This observation is similar to the report of Trevino et al 2014 where they noted that cotrimoxazole may no longer be effective in the management of Stenotrophomonas infection. Most isolates were susceptible to the fluoroquinolones tested. This implies that fluoroquinolones may be a good candidate for the treatment of Stenotrophomonas associated infections after quality clinical trials. Finally we noted that environmental factors could have induced the development of resistance to antimicrobial agents as none of our isolates has no association with the hospital environment. The implication of this is that an immunocompromised individual may acquire a resistant Stenotrophomonas bug from the environment hence the importance of individual public hygiene
References Fig2: Biofilm formation characteristics of isolate
1. Brooke, J. S. (2012). Stenotrophomonas maltophilia: an emerging global opportunistic pathogen. Clinical microbiology reviews, 25(1), 2-41. 2. Brooke, J. S. (2014). New strategies against Stenotrophomonas maltophilia: a serious worldwide intrinsically drug-resistant opportunistic pathogen. Expert review of anti-infective therapy, 12(1), 1-4
Table2:Antibiotic susceptibility pattern of Isolates
