scholarly journals Isolation and Study of Bacteriophages Specific Against Multidrug Resistant Salmonella spp. and Assessment of their Therapeutic Potential

2021 ◽  
Author(s):  
Khatuna Makalatia ◽  
Elene Kakabadze ◽  
Nino Grdzelishvili ◽  
Nata Bakuradze ◽  
Nino Chanishvili
Keyword(s):  
Therapeutic Potential ◽  
Multidrug Resistant ◽  
In Vitro Tests ◽  
Salmonella Spp ◽  
Clinical Strains ◽  
Additional Tool ◽  
Salmonella Infections ◽  
Microbiological Methods ◽  
Genetic Features

Within the scope of the study, clinical non-typhoidal Salmonella were isolated in Armenia and Georgia and identified based on conventional microbiological methods and MALDI-TOF MS. These isolates were further analysed by serotyping (White-Kauffmann-Le Minor scheme) and their antimicrobial susceptibility profiles were defined. A total of 40 antibiotic resistance profiles were identified, of which 35 were characteristic of clinical strains. Out of a total of 345 isolates, 238 strains from Georgia, Armenia and Ireland were eventually selected for our study.Using the strains of this collection, 13 new bacteriophages were isolated, characterized by biological and genetic features. Based on the data obtained, phages were classified and the peculiarities of their life cycle were determined (virulent-lytic, moderate-lysogenic).Analysis of the sequencing results showed that only one of the 12 phages identified as temperate phage (vB_GEC_ TR), it belongs to the family Podoviridae, genus-Laderbergvirus. While the other 11 phages are virulent, they are related to well-known and characterized phages, which are used in various phage preparations. Analysis of their genomes did not show any lysogeny associated genes. Among the virulent phages, 6 are members of Myoviridae family (vB_GEC_B1, vB_GEC_B3, vB_GEC_MG, vB_GEC_BS, vB_GEC_NS7, vB_GEC_7A) and 5 of the Syphoviridae family (vB_GEC_N5, vB_GEC_N8, vB_GEC_M4, vB_GEC_M5, vB_GEC_Hi). In vitro tests revealed that the phages - vB_GEC_B1, vB_GEC_BS, vB_GEC_B3, vB_GEC_NS7, vB-GEC-N8 showed high activity (60% to 80%) against the examined strains. The phages have been shown to be more effective against clinical strains (≈90%) than against veterinary strains (≈70%). The strains susceptible to these phages were mainly S.typhimurium and S. Enteritidis serovars and are largely of clinical origin. Based on our research we can conclude that the application of phages as an additional tool for the treatment of MDR Salmonella infections seems to be plausible. Phages are natural and specific antibacterial agents, which can lyse bacteria.irrespective of their AMR status, whilst leaving the commensal microflora unharmed. This is one of the main advantages of phages in comparison to antibiotics. The phages tested in this study showed potential for application in phage therapy against MDR Salmonella infections.

scholarly journals In Vitro Activity of 3 Commercial Bacteriophage Cocktails Against Salmonella and Shigella spp. Isolates of Human Origin

2018 ◽  
Vol 3 (1) ◽  
pp. 72 ◽  
Author(s):  
Odette J. Bernasconi ◽  
Valentina Donà ◽  
Regula Tinguely ◽  
Andrea Endimiani
Keyword(s):  
Multidrug Resistant ◽  
In Vivo Studies ◽  
Salmonella Spp ◽  
Salmonella Infections ◽  
Shigella Spp ◽  
Resistant Strains ◽  
Emergence Of Resistance ◽  
First Time

Background: Salmonella and Shigella spp. are 2 of the most frequent and deadly enteric bacterial pathogens recorded worldwide. In developing countries Salmonella infections are responsible for many deaths annually and these mortality rates are prone to increase due to the emergence of resistance to antibiotics. In this overall scenario new alternative therapeutic approaches are needed.Methods: For the first time, we investigated the activity of 3 commercial bacteriophage cocktails (INTESTI, Septaphage, PYO) against a collection of contemporary Salmonella spp. (n = 30) and Shigella spp. (n = 20) strains isolated in Switzerland. Phage susceptibility was determined by implementing the spot test.Results: The overall susceptibility of Salmonella spp. to INTESTI and Septaphage was 87% and 77%, respectively. With regard to Shigella spp., the overall susceptibility to INTESTI and Septaphage was 95% and 55%, respectively. PYOwas observed to be active against only 10% of Salmonella spp. but against 95% of Shigella spp.Conclusions: Our results seem promising, especially for the INTESTI biopreparation against Salmonella enterica infections. Nevertheless, such speculation should be supported by further in vivo studies to confirm efficacy and safety of the cocktails. We also emphasize the importance of large in vitro screening analyses aimed to assess the activity of such biopreparations against contemporary multidrug-resistant strains that are emerging worldwide.Keywords: commercial; bacteriophages; Salmonella; Shigella cocktails

scholarly journals Characterization of Salmonella Isolates from Various Geographical Regions of the Caucasus and Their Susceptibility to Bacteriophages

Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1418
Author(s):  
Khatuna Makalatia ◽  
Elene Kakabadze ◽  
Jeroen Wagemans ◽  
Nino Grdzelishvili ◽  
Nata Bakuradze ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Phage Therapy ◽  
Therapeutic Potential ◽  
Multidrug Resistant ◽  
Antimicrobial Treatment ◽  
Additional Tool ◽  
Food Borne ◽  
Microbiological Methods ◽  
Geographical Regions ◽  
Susceptibility Profiles

Non-typhoidal Salmonella present a major threat to animal and human health as food-borne infectious agents. We characterized 91 bacterial isolates from Armenia and Georgia in detail, using a suite of assays including conventional microbiological methods, determining antimicrobial susceptibility profiles, matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, serotyping (using the White-Kauffmann-Le Minor scheme) and genotyping (repetitive element sequence-based PCR (rep-PCR)). No less than 61.5% of the isolates were shown to be multidrug-resistant. A new antimicrobial treatment strategy is urgently needed. Phage therapy, the therapeutic use of (bacterio-) phages, the bacterial viruses, to treat bacterial infections, is increasingly put forward as an additional tool for combatting antibiotic resistant infections. Therefore, we used this representative set of well-characterized Salmonella isolates to analyze the therapeutic potential of eleven single phages and selected phage cocktails from the bacteriophage collection of the Eliava Institute (Georgia). All isolates were shown to be susceptible to at least one of the tested phage clones or their combinations. In addition, genome sequencing of these phages revealed them as members of existing phage genera (Felixounavirus, Seunavirus, Viunavirus and Tequintavirus) and did not show genome-based counter indications towards their applicability against non-typhoidal Salmonella in a phage therapy or in an agro-food setting.

Detection of invA and blaCTM-genes in Salmonella spp isolated from febrile patients in Lagos hospitals, Nigeria

2021 ◽  
Vol 1 (3) ◽  
pp. 1-10
Author(s):  
Kabiru O. Akinyemi ◽  
Christopher O. Fakorede ◽  
Rebecca O. Abegunrin ◽  
Samuel O. Ajoseh ◽  
Abdul-Azeez A. Anjorin ◽  
...  
Keyword(s):  
Unknown Origin ◽  
Diffusion Method ◽  
Salmonella Spp ◽  
Disk Diffusion Method ◽  
Gene Markers ◽  
Extended Spectrum Beta Lactamase ◽  
Inva Gene ◽  
Salmonella Infections ◽  
Antimicrobial Resistance Genes

Salmonella infections remain a global challenge. The culture method is the gold standard for the detection of genus Salmonella. Application of Polymerase Chain Reaction (PCR) has become an effective tool for the detection of virulence and antimicrobial resistance genes. This study investigated the prevalence of Salmonella by culture and detection of invA gene and blaCTX-M and blaCTX-M-3 gene markers by PCR. A total of 612 blood samples were collected from hospitalized febrile patients between March 2020 and April 2021. The samples were cultured, isolates identified by standard method with Analytical Profile Index (API 20-E) kits and were subjected to in-vitro antimicrobial susceptibility test (AST) using disk diffusion method. Extended-spectrum beta-lactamase (ESBL) detection was carried out by double-disc synergy test. Detection of invA gene and antibiotic-resistant genes makers was done by qPCR. A total of 24 Salmonella isolates were identified given a prevalence of 3.9% Salmonella-associated bacteraemia. Children within 1-10 years with persistent pyrexia of unknown origin (PUO) accounted for 50% of the Salmonella isolated with a mean age of 5.299 years. Specifically, 75% (18/24) Salmonella isolates and their corresponding samples of positive Salmonella culture were positive for the invA gene. The AST results indicated 100% Salmonella isolates developed resistance to ceftazidime, cefotaxime , augmentin, ampicillin, ertapenem, and doripenem. None of drug resistant-Salmonella isolates expressed ESBL enzyme phenotypically. Seven resistance patterns were observed, and the pattern CAZ-CTX-OFL-AUG-NIT-AMP-ETR-DOR was the most encountered pattern. Twelve (50%) Salmonella isolates harbored the blaCTX-M and blaCTX-M-3 genes and were mostly from children. The study has added to the growing knowledge on the suitability of the invA gene primer set as a PCR target for the detection of Salmonella. It also revealed a paradigm shift in the occurrence of invasive Salmonella harboring blaCTX-M and blaCTX-M-3 genes in PUO cases. There is a need for judicious use of cephalosporin and carbapenem antibiotics to preserve their efficacies.

Molecular detection of biofilm, virulence and antimicrobial resistance associated genes of Salmonella serovars isolated from pig and chicken of Mizoram, India

2019 ◽  
Author(s):  
S. Chakraborty ◽  
P. Roychoudhury ◽  
I. Samanta ◽  
P. K. Subudhi ◽  
Lalhruaipuii Lalhruaipuii ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Virulence Genes ◽  
Antimicrobial Agents ◽  
Virulence Gene ◽  
Microtiter Plate ◽  
Multidrug Resistant ◽  
Salmonella Spp ◽  
Microtiter Plate Assay ◽  
Antimicrobial Sensitivity ◽  
Salmonella Infections

Salmonella has emerged as one of the most important food-borne pathogens for humans as well as animals and the ability of biofilm formation by these bacteria has further aided their survival in unfavorable environment. Characterization of these biofilm producing bacteria isolated from pigs and chicken may lead to formulation of strategies for prevention and control of Salmonella infections. Therefore, the present study was conducted to isolate Salmonella from pigs and poultry of Mizoram, determine their biofilm producing ability by phenotypic and genotypic methods along with their virulence and antimicrobial resistance properties. A total of 15 Salmonella spp. (pig=9, poultry=6) was isolated from 100 faecal samples from pigs and 50 cloacal swabs from poultry and biofilm producing ability of the isolates was determined by microtiter plate assay. A total of 10 (66.67%) isolates were found to be biofilm producer. All the biofilm producing bacterial isolates were investigated for antimicrobial sensitivity and distribution of selected biofilm associated genes (csgA, csgD and adrA), virulence genes (invA, stn and sefA) and antimicrobial resistance (AMR) genes (blaTEM, blaSHV and blaCTX-M). The most prevalent resistance was found against ceftazidime (80%), ceftriaxone (80%), cefixime (70%), cefotaxime (70%), gentamicin (70%), cotrimoxazole (60%) and ampicillin (60%). A total of 7 (70%) isolates were resistant to at least three different classes of antimicrobial agents and considered as multidrug resistant. All the isolates were positive for adrA (100%) but negative for csgA and csgD genes. The most frequent virulence gene was invA (100%) and stn (100%). Among the AMR genes, blaTEM (60%) was found to be the major AMR determinants. Moreover, a total of 7 Salmonella isolates were positive for at least one of t biofilm associated genes, virulence genes and AMR genes.

scholarly journals Formulation of Improved Traditional Drugs against virulent species of Salmonella spp in Benin: assessment of the properties from Uvaria chamae, Lantana camara and Phyllantus amarus in Benin, West Africa

2019 ◽  
Author(s):  
Boris LEGBA ◽  
Victorien DOUGNON ◽  
Carène GBAGUIDI ◽  
Alidah ANIAMBOSSOU ◽  
Esther DEGUENON ◽  
...  
Keyword(s):  
Aqueous Extract ◽  
Bacterial Load ◽  
Scientific Data ◽  
Lantana Camara ◽  
Toxicity Tests ◽  
In Vitro Tests ◽  
Post Inoculation ◽  
Salmonella Spp

Abstract Background Uvaria chamae (Annonaceae), Phyllantus amarus (Phyllantaceae) and Lantana camara (Verbenaceae) are empirically alleged to be used as Beninese medicinal plants in the treatment of salmonellosis. This study aimed to produce scientific data on in vitro and in vivo efficacy of Uvaria chamae, Lantana camara and Phyllantus amarus on multiresistant Salmonella spp isolated in Benin.Results After in vitro tests on aqueous and ethanolic extracts of Uvaria chamae, Lantana camara and Phyllantus amarus , only the aqueous extract of Uvaria chamae (leaves) showed the best anti- Salmonella ’s activity. It has been used for the following experiments. The induction of salmonellosis revealed 9.0 10 8 CFU/ml was optimal concentration for triggering and maintaining the symptoms in chicks. This infective concentration has been used for in vivo assessment. 24 hours post inoculation later, the symptoms of salmonellosis (wet cloaca, diarrhea stool and somnolence) were observed in infected groups. After seven days of treatment, the rate of reduction of bacterial load at 100 mg / L, 200 mg / L, 400 mg / L of this extract was 85%, 52.38% and 98% respectively in the chicks groups infected with Salmonella Typhimurium ATCC 14028. About the groups infected with Salmonella spp (virulent strain), the rate of reduction of bacterial load at 100 mg / L, 200 mg / L, 400 mg / L of this extract was 0%, 98.66% and 99.33%. The toxicity tests did not show any significant effect of the Uvaria chamae ’s extract on the biochemical and hematological parameters of the chicks.Conclusion The aqueous extract of Uvaria chamae is active in vitro and in vivo on multiresistant strains of Salmonella spp . This plant is a good candidate for the development of an improved traditional medicine for the management of salmonellosis.

scholarly journals Identification of the antibacterial mechanism of cryptotanshinone on methicillin-resistant Staphylococcus aureus using bioinformatics analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiwei Zhong ◽  
Haidan Wang ◽  
Yun Zhuang ◽  
Qun Shen
Keyword(s):  
Staphylococcus Aureus ◽  
Bioinformatics Analysis ◽  
Salvia Miltiorrhiza ◽  
Microarray Dataset ◽  
Antimicrobial Activities ◽  
Dilution Method ◽  
In Vitro Tests ◽  
Methicillin Resistant ◽  
Clinical Strains

AbstractCryptotanshinone (CT) is an extract from the traditional Chinese medicine Salvia miltiorrhiza, which inhibits the growth of methicillin-resistant Staphylococcus aureus (MRSA) in vitro. This study aims to determine the antibacterial mechanisms of CT by integrating bioinformatics analysis and microbiology assay. The microarray data of GSE13203 was retrieved from the Gene Expression Omnibus (GEO) database to screen the differentially expressed genes (DEGs) of S. aureus strains that were treated with CT treatment. Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used to identify the potential target of CT. Data mining on the microarray dataset indicated that pyruvate kinase (PK) might be involved in the antimicrobial activities of CT. The minimum inhibition concentrations (MICs) of CT or vancomycin against the MRSA strain ATCC43300 and seven other clinical strains were determined using the broth dilution method. The effects of CT on the activity of PK were further measured. In vitro tests verified that CT inhibited the growth of an MRSA reference strain and seven other clinical strains. CT hampered the activity of the PK of ATCC43300 and five clinical MRSA strains. CT might hinder bacterial energy metabolism by inhibiting the activity of PK.

scholarly journals 1592. In Vitro Activity of Ceftolozane/Tazobactam (C/T) Against Enterobacteriaceae and Pseudomonas aeruginosa Circulating in Chile

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S581-S581
Author(s):  
Lina M Rivas ◽  
Jose R W Martínez ◽  
Maria Spencer ◽  
Lorena Porte ◽  
Francisco Silva ◽  
...  
Keyword(s):  
Tertiary Care ◽  
Multidrug Resistant ◽  
Global Public Health ◽  
Health Crisis ◽  
Clinical Strains ◽  
E Coli ◽  
Highly Active ◽  
Complex Figure ◽  
Wide Range

Abstract Background The widespread dissemination of carbapenem-resistant (CR) P. aeruginosa and Enterobacteriaceae has created a major global public health crisis. C/T is a recently approved therapeutic which consists of the combination of a novel cephalosporin (ceftolozane) and tazobactam (a β-lactamase inhibitor). C/T has shown good activity against a wide range of multidrug-resistant (MDR) Gram negatives, being particularly interesting as an alternative for MDR P. aeruginosa. We aimed to determine the activity of C/T against clinical strains of Enterobacteriaceae and P. aeruginosa recovered in 4 large clinical centers from Chile. Methods We analyzed 434 isolates of Enterobacteriaceae (347 E. coli, 66 K. pneumoniae, 21 Enterobacter cloacae complex) and 57 P. aeruginosa collected during 2017 from 4 tertiary care institutions in Santiago, Chile. Identification was performed as per each local clinical microbiology lab. Susceptibility testing was performed by broth microdilution using customized Sensititre plates (Trek). Carba-NP was performed to screen for carbapenemase production. Susceptibilities were analyzed as per 2019 CLSI breakpoints. Results The MIC50/90 for C/T against Enterobacteriaceae and P. aeruginosa were 1/4 μg/mL and 2/16 μg/mL, respectively. In Enterobacteriaceae, susceptibility to C/T reached 92% in E. coli (Figure 1A), 91% in E. cloacae complex (Figure 1B) and 70% in K. pneumoniae (Figure 1C). Remarkably, C/T remained active against 58% (33/57) of CR Enterobacteriaceae (Figure 2A). Among Carba-NP-negative CR isolates (46%, 26/57), susceptibility to C/T was 54% (Figure 3 A–C). In P. aeruginosa, the overall susceptibility to C/T was 81% (Figure 1D), maintaining activity against 69% (25/36) of CR strains (Figure 2B). Importantly, susceptibility to C/T in CR P. aeruginosa isolates with a negative Carba-NP (67%, 24/36) was 83% (20/24) (Figure 3D). Conclusion In this multicenter study, we observed that C/T was highly active against clinical isolates of Enterobacteriaceae and P. aeruginosa. Of note, C/T remained active against a large proportion of CR clinical strains. Moreover, the activity of C/T was particularly high against CR P. aeruginosa isolates with a negative Carba-NP. Disclosures All authors: No reported disclosures.

scholarly journals Prodigiosin Modulates the Immune Response and Could Promote a Stable Atherosclerotic Lession in C57bl/6 Ldlr-/- Mice

2020 ◽  
Vol 21 (17) ◽  
pp. 6417 ◽  
Author(s):  
Alejandro Cuevas ◽  
Nicolás Saavedra ◽  
Luis A. Salazar ◽  
Marcela F. Cavalcante ◽  
Jacqueline C. Silva ◽  
...  
Keyword(s):  
Gene Expression ◽  
Immune Response ◽  
Atherosclerotic Plaque ◽  
Therapeutic Potential ◽  
Inflammatory Marker ◽  
Interleukin 2 ◽  
Atheromatous Plaque ◽  
In Vitro Tests ◽  
Significant Difference

Atherosclerosis is a chronic inflammatory disease, whose progression and stability are modulated, among other factors, by an innate and adaptive immune response. Prodiginines are bacterial secondary metabolites with antiproliferative and immunomodulatory activities; however, their effect on the progression or vulnerability of atheromatous plaque has not been evaluated. This study assessed the therapeutic potential of prodigiosin and undecylprodigiosin on inflammatory marker expression and atherosclerosis. An in vitro and in vivo study was carried out. Migration, low-density lipoprotein (LDL) uptake and angiogenesis assays were performed on cell types involved in the pathophysiology of atherosclerosis. In addition, male LDL receptor null (Ldlr-/-) C57BL/6J mice were treated with prodigiosin or undecylprodigiosin for 28 days. Morphometric analysis of atherosclerotic plaques, gene expression of atherogenic factors in the aortic sinus and serum cytokine quantification were performed. The treatments applied had slight effects on the in vitro tests performed, highlighting the inhibitory effect on the migration of SMCs (smooth muscle cells). On the other hand, although no significant difference in atherosclerotic plaque progression was observed, gene expression of IL-4 and chemokine (C-C motif) ligand 2 (Ccl2) was downregulated. In addition, 50 µg/Kg/day of both treatments was sufficient to inhibit circulating tumor necrosis factor alpha (TNF-α), interleukin-2 (IL-2) and interferon-gamma (IFN-γ) in serum. These results suggested that prodigiosin and undecylprodigiosin modulated inflammatory markers and could have an impact in reducing atherosclerotic plaque vulnerability.

A Review of Saurauia roxburghii Wall. (Actinidiacaea) as a Traditional Medicinal Plant, Its Phytochemical Study and Therapeutic Potential

2020 ◽  
Vol 20 (19) ◽  
pp. 2036-2051
Author(s):  
Afsana Nahrin ◽  
Md. Junaid ◽  
Syeda Samira Afrose ◽  
Muhammad Shaiful Alam ◽  
S.M. Zahid Hosen ◽  
...  
Keyword(s):  
Ursolic Acid ◽  
Therapeutic Potential ◽  
Wide Spectrum ◽  
Relevant Information ◽  
In Vitro Tests ◽  
Pharmacological Activities ◽  
Phytochemical Study ◽  
Corosolic Acid

Saurauia roxburghii Wall. is an interesting plant, found growing chiefly along the eastern and south-eastern countries of Asia. The various ethnic groups of these regions use the plant as a medication for relieving a wide spectrum of diseases and conditions, including indigestion, boils, fever, gout, piles, eczema, asthma, ulcers, bronchitis, epilepsy, and hepatitis B. This review aims to appraise the vernacular information, botanical characterization, geographical distribution, traditional uses, phytochemistry, and pharmacological activities of S. roxburghii as well as to conduct a critical analysis on the findings. To understand the therapeutic potential and provide an overall idea about the ethnomedicinal practices, phytochemistry, and pharmacological activities of S. roxburghii, relevant information was collected via a library and electronic search of online journals, books, and reputed databases. Phytochemical examination revealed the presence of alkaloids, glycosides, O-glycosides, flavonoids, carbohydrates, saponins, steroids, reducing sugars, tannins, phlobatannins, and triterpenoids. The sterols were identified as Stigmasterol and beta-Sitosterol. The triterpenes were found to be Ursolic acid, Corosolic acid, Maslinic acid, 24-Hydroxy corosolic acid, 3b,7b,24-trihydroxy-urs-12-en-28-oic acid, Oleanolic acid, beta-Amyrin, cis-3-O-p-Hydroxycinnamoyl ursolic acid, trans-3-O-p- Hydroxycinnamoyl ursolic acid, and 7,24-dihydroxyursolic acid. Several in-vivo and in-vitro tests revealed anti-bacterial, anti-cancer, anti-diabetic, anti-oxidant, and anti-viral activities of the plant leaves. Detailed analysis of the information collected on S. roxburghii suggested some promising leads for future drug development. However, many scientific gaps were found in the study of this and further extensive investigation is needed to fully understand the mechanism of action of the active constituents and exploit its therapeutic promises.

scholarly journals COMBINATORIAL EFFECT OF D-AMINOACIDS AND TETRACYCLINE AGAINST PSEUDOMONAS AERUGINOSA BIOFILM

2016 ◽  
Vol 8 (11) ◽  
pp. 216
Author(s):  
H. Jayalekshmi ◽  
C. Harikrishnan ◽  
Sajin Sali ◽  
N. Kaushik ◽  
Norin Mary G. Victus ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Wound Dressing ◽  
Ex Vivo ◽  
Multidrug Resistant ◽  
Antibiofilm Activity ◽  
Porcine Skin ◽  
Clinical Strains ◽  
Microtitre Plate Assay

Objective: The present study attempted to evaluate the anti-biofilm activity of D-amino acids (D-AAs) on Pseudomonas aeruginosa and determine if the combination of D-AAs with tetracycline enhances the anti-biofilm activity in vitro and ex vivo.Methods: Different D-AAs were tested for antibiofilm activity against wild type P. aeruginosa PAO1 and two multidrug resistant P. aeruginosa clinical strains in the presence of sub inhibitory concentrations of tetracycline using crystal violet microtitre plate assay. Results were further validated using in vitro wound dressing and ex vivo porcine skin models followed by cytotoxicity and hemocompatibility studies.Results: D-tryptophan (5 mmol) showed 61 % reduction in biofilm formation of P. aeruginosa. Interestingly combinatorial effect of 5 mmol D-tryptophan and 0.5 minimum inhibitory concentration (MIC) (7.5µg/ml) tetracycline showed 90% reduction in biofilm formation. 5 mmol D-methionine shows 28 % reduction and combination with tetracycline shows 41% reduction in biofilm formation of P. aeruginosa. D-leucine and D-tyrosine alone or in combination with tetracycline did not show significant anti-biofilm activity. D tryptophan-tetracycline combination could reduce 80 % and 77 % reduction in biofilm formation in two multi drug resistant P. aeruginosa clinical strains. D-tryptophan-tetracycline-combination could also reduce 76% and 66% reduction in biofilm formation in wound dressing model and porcine skin explant respectively. The cytotoxicity and hemocompatibility studies did not show significant toxicity when this combination was used.Conclusion: The results established the potential therapeutic application of D-tryptophan alone or in combination with tetracycline for treating biofilm associated clinical problems caused by P. aeruginosa.

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