Chemical genetic approaches for the discovery of bacterial cell wall inhibitors.

Antimicrobial resistance (AMR) in bacterial pathogens is a worldwide health issue. The innovation gap in discovering new antibiotics has remained a significant hurdle in combating the AMR problem. Currently, antibiotics target various vital components of the bacterial cell envelope, nucleic acid and protein biosynthesis machinery and metabolic pathways essential for bacterial survival. The critical role of the bacterial cell envelope in cell morphogenesis and integrity makes it an attractive drug target. While a significant number of in-clinic antibiotics target peptidoglycan biosynthesis, several components of the bacterial cell envelope have been overlooked. This review focuses on various antibacterial targets in the bacterial cell wall and the strategies employed to find their novel inhibitors. This review will further elaborate on combining forward and reverse chemical genetic approaches to discover antibacterials that target the bacterial cell envelope.

Phylogeny-guided genome mining of roseocin family lantibiotics to generate improved variants of roseocin.

Roseocin, the two-peptide lantibiotic from Streptomyces roseosporus, carries extensive intramolecular (methyl)lanthionine bridging in the peptides and exhibits synergistic antibacterial activity against clinically relevant Gram-positive pathogens. Both peptides have a conserved leader but a diverse core region. The biosynthesis of roseocin involves post-translational modification of the two precursor peptides by a single promiscuous lanthipeptide synthetase, RosM, to install an indispensable disulfide bond in the Rosα core along with four and six thioether rings in Rosα and Rosß cores, respectively. RosM homologs in the phylum actinobacteria were identified here to reveal twelve other members of the roseocin family which diverged into three types of biosynthetic gene clusters (BGCs). Further, the evolutionary rate among the BGC variants and analysis of variability within the core peptide versus leader peptide revealed a phylum-dependent lanthipeptide evolution. Analysis of horizontal gene transfer revealed its role in the generation of core peptide diversity. The naturally occurring diverse congeners of roseocin peptides identified from the mined novel BGCs were carefully aligned to identify the conserved sites and the substitutions in the core peptide region. These selected sites in the Rosα peptide were mutated for permitted substitutions, expressed heterologously in E. coli, and post-translationally modified by RosM in vivo. Despite a limited number of generated variants, two variants, RosαL8F and RosαL8W exhibited significantly improved inhibitory activity in a species-dependent manner compared to the wild-type roseocin. Our study proves that a natural repository of evolved variants of roseocin is present in nature and the key variations can be used to generate improved variants.

Disulfiram enhances meropenem activity against NDM- and IMP-producing carbapenem-resistant Acinetobacter baumannii infections.

OBJECTIVES: To evaluate the in vitro and in vivo efficacy of the FDA-approved drug disulfiram in combination with meropenem against MBL-expressing carbapenem-resistant Acinetobacter baumannii. METHODS: Chequerboard and antibiotic resistance reversal analysis were performed using 25 clinical isolates producing different MBLs. Three representative strains harbouring NDM, IMP or non-MBL genes were subjected to a time-kill assay to further evaluate this synergistic interaction. Dose-dependent inhibition by disulfiram was assessed to determine IC50 for NDM-1, IMP-7, VIM-2 and KPC-2. Further, to test the efficacy of meropenem monotherapy and meropenem in combination with disulfiram against NDM- and IMP-harbouring A. baumannii, an experimental model of systemic infection and pneumonia was developed using BALB/c female mice. RESULTS: Chequerboard and antibiotic reversal assay displayed a synergistic interaction against MBL-expressing A. baumannii strains with 4- to 32-fold reduction in MICs of meropenem. In time-kill analysis, meropenem and disulfiram exhibited synergy against NDM- and IMP-producing carbapenem-resistant A. baumannii (CRAb) isolates. In vitro dose-dependent inhibition analysis showed that disulfiram inhibits NDM-1 and IMP-7 with IC50 values of 1.5 ± 0.6 and 16.25 ± 1.6 µM, respectively, with slight or no inhibition of VIM-2 (<20%) and KPC-2. The combination performed better in the clearance of bacterial load from the liver and spleen of mice infected with IMP-expressing CRAb. In the pneumonia model, the combination significantly decreased the bacterial burden of NDM producers compared with monotherapy. CONCLUSIONS: These results strongly suggest that the combination of disulfiram and meropenem represents an effective treatment option for NDM- and IMP-associated CRAb infections.

An Ensemble Deep Learning Model for Automatic Modulation Classification in 5G and Beyond IoT Networks.

With rapid advancement in artificial intelligence (AI) and machine learning (ML), automatic modulation classification (AMC) using deep learning (DL) techniques has become very popular. This is even more relevant for Internet of things (IoT)-assisted wireless systems. This paper presents a lightweight, ensemble model with convolution, long short term memory (LSTM), and gated recurrent unit (GRU) layers. The proposed model is termed as deep recurrent convoluted network with additional gated layer (DRCaG). It has been tested on a dataset derived from the RadioML2016(b) and comprises of 8 different modulation types named as BPSK, QPSK, 8-PSK, 16-QAM, 4-PAM, CPFSK, GFSK, and WBFM. The performance of the proposed model has been presented through extensive simulation in terms of training loss, accuracy, and confusion matrix with variable signal to noise ratio (SNR) ranging from -20 dB to +20 dB and it demonstrates the superiority of DRCaG vis-a-vis existing ones.

Evaluation of Role of Visual Inspection Using Acetic Acid (VIA) and Exfoliative Cytology in Screening and Early Detection of Oral Premalignant Lesions and Oral Cancer.

OBJECTIVE: Oral cancer accounts for 50-70% of total cancer mortality. VIA screening has drastically changed the morbidity and mortality related to cervical cancer. In present study, we assessed the role of 5% Acetic Acid as a vital stain in oral mucosa of chronic tobacco chewers, to know if it can help in early diagnosis and improved prognosis of oral malignancies and to assess the sensitivity and specificity of VIA and exfoliative cytology for screening of Oral premalignant and malignant lesions in high risk population with limited health care infrastructure. METHODS: This was an outpatient department based prospective study done in a tertiary hospital over a period of two years. 150 cases with a history of chronic tobacco use were evaluated. Visual inspection (VI) followed by VIA using 5% Acetic acid was done. Oral scrapes were taken for cytological examination followed by biopsy for histopathological evaluation, wherever possible. RESULTS: Sensitivity, specificity, PPV, NPV and accuracy of VIA and Exfoliative cytology was 71%, 65%, 83%, 48%, 69% and 98%, 65%, 89%, 92%, 88% respectively keeping histology as gold standard. CONCLUSION: Acetic acid along with exfoliative cytology can be used as simple, cost effective and convenient methods for mass screening of OPMDs and OSCC in high risk population where biopsy is not possible.
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Roseocin, a novel two-component lantibiotic from an actinomycete.

Lantibiotics are lanthionine ring containing natural products that belong to the class of ribosomally synthesized and posttranslationally modified peptides (RiPPs). Recent expansion in the availability of microbial genome data and in silico analysis tools have accelerated the discovery of these promising alternatives to antibiotics. Following the genome-mining approach, a biosynthetic gene cluster for a putative two-component lantibiotic, roseocin, was identified in the genome of an Actinomycete, Streptomyces roseosporus NRRL 11379. Posttranslationally modified lanthipeptides of this cluster were obtained by heterologous expression of the genes in Escherichia coli, and were in vitro reconstituted to their bioactive form by exploiting commercial proteases like endoproteinase GluC, and proteinase K. The two peptides displayed synergistic antimicrobial activity against Gram-positive bacteria including the WHO high-priority pathogens, MRSA and VRE. Structural characterization confirmed the installation of four (methyl)lanthionine rings with an indispensable disulfide bond in the α-peptide, and six (methyl)lanthionine rings in the ß-peptide, by a single promiscuous lanthionine synthetase, RosM. Roseocin is the first two-component lantibiotic from a non-Firmicute, with extensive lanthionine bridging.

Randomised Controlled Clinical Study of Injection Caroverine and Ginkgo Biloba Extract in Cochlear Synaptic Tinnitus.

Tinnitus, also known as phantom auditory perception, is an annoying symptom and 13-17% of population reports bothersome tinnitus. Cochlear synaptic tinnitus is the most common type. Many treatments have been tried but none is yet considered to be well established. To evaluate effect of Inj.Caroverine and Ginkgo Biloba extract in cochlear synaptic tinnitus in terms of improving tinnitus grading, tinnitus matching and quality of life of patient. It is Randomised controlled study, conducted in department of ENT, on 86 patients, who met inclusion criteria, divided into 4 groups. Gr1-Inj Caroverin, Gr2-Inj Placebo, Gr3-Ginkgo Biloba extract, Gr4-Placebo as extract. A single dose infusion of caroverine immediately improves tinnitus grading and matching and provides immediate relief in reducing severity of tinnitus in 54.54% cases but improvement was not sustained in caroverine group at 3 month and 6 month follow-up after infusion. Ginkgo biloba also is effective in improving tinnitus grading and matching in 31.8% cases and improvement was sustained in ginkgo biloba group even after 3 month of cessation of treatment i.e. at 6 month follow-up. It is suggested that Inj.Caroverine as intravenous infusion should be given in severe cases of tinnitus to reduce its severity immediately and then patient should be put on Tab.Ginkgo biloba for a period of 3 months to provide sustained and long lasting relief. Thus combination therapy of Inj.Caroverin and Tab.Ginkgo Biloba, appropriately tailored to the need of patient will provide better results in greater majority of patients.

A huge pleomorphic adenoma of the submandibular salivary gland.

The most common tumour of salivary gland is pleomorphic adenoma (PA). They are benign, painless, can grow into big tumours but usually do not affect nerves or lymph nodes. PA most commonly occurs in the parotid gland but it may involve submandibular, lingual and minor salivary glands also. They can attain giant proportions and weigh several kilograms. We report a giant PA arising in the submandibular gland and treated by complete surgical excision without any complication. A female patient presented with a tumour in the submandibular region and front of neck with a history of more than 18 years. The weight of the resected mass was 4.35 kg. Patient's fear of surgery and lack of awareness were the main reasons for her long-standing swelling. Such giant PAs of the submandibular gland are very rare in medical literature.

Non-ribosomal peptide synthetases: Identifying the cryptic gene clusters and decoding the natural product.

Non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) present in bacteria and fungi are the major multi-modular enzyme complexes which synthesize secondary metabolites like the pharmacologically important antibiotics and siderophores. Each of the multiple modules of an NRPS activates a different amino or aryl acid, followed by their condensation to synthesize a linear or cyclic natural product. The studies on NRPS domains, the knowledge of their gene cluster architecture and tailoring enzymes have helped in the in silico genetic screening of the ever-expanding sequenced microbial genomic data for the identification of novel NRPS/PKS clusters and thus deciphering novel non-ribosomal peptides (NRPs). Adenylation domain is an integral part of the NRPSs and is the substrate selecting unit for the final assembled NRP. In some cases, it also requires a small protein, the MbtH homolog, for its optimum activity. The presence of putative adenylation domain and MbtH homologs in a sequenced genome can help identify the novel secondary metabolite producers. The role of the adenylation domain in the NRPS gene clusters and its characterization as a tool for the discovery of novel cryptic NRPS gene clusters are discussed.

Complementarity among plant growth promoting traits in rhizospheric bacterial communities promotes plant growth.

An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants.

Biodiversity acts as insurance of productivity of bacterial communities under abiotic perturbations.

Anthropogenic disturbances are detrimental to the functioning and stability of natural ecosystems. Critical ecosystem processes driven by microbial communities are subjected to these disturbances. Here, we examine the stabilizing role of bacterial diversity on community biomass in the presence of abiotic perturbations such as addition of heavy metals, NaCl and warming. Bacterial communities with a diversity gradient of 1-12 species were subjected to the different treatments, and community biomass (OD600) was measured after 24 h. We found that initial species richness and phylogenetic structure impact the biomass of communities. Under abiotic perturbations, the presence of tolerant species in community largely contributed in community biomass production. Bacterial diversity stabilized the biomass across the treatments, and differential response of bacterial species to different perturbations was the key reason behind these effects. The results suggest that biodiversity is crucial for maintaining the stability of ecosystem functioning and acts as ecological insurance under abiotic perturbations. Biodiversity in natural ecosystems may also uphold the ecosystem functioning under anthropogenic disturbance.

Novel LanT associated lantibiotic clusters identified by genome database mining.

BACKGROUND: Frequent use of antibiotics has led to the emergence of antibiotic resistance in bacteria. Lantibiotic compounds are ribosomally synthesized antimicrobial peptides against which bacteria are not able to produce resistance, hence making them a good alternative to antibiotics. Nisin is the oldest and the most widely used lantibiotic, in food preservation, without having developed any significant resistance against it. Having their antimicrobial potential and a limited number, there is a need to identify novel lantibiotics. METHODOLOGY/FINDINGS: Identification of novel lantibiotic biosynthetic clusters from an ever increasing database of bacterial genomes, can provide a major lead in this direction. In order to achieve this, a strategy was adopted to identify novel lantibiotic biosynthetic clusters by screening the sequenced genomes for LanT homolog, which is a conserved lantibiotic transporter specific to type IB clusters. This strategy resulted in identification of 54 bacterial strains containing the LanT homologs, which are not the known lantibiotic producers. Of these, 24 strains were subjected to a detailed bioinformatic analysis to identify genes encoding for precursor peptides, modification enzyme, immunity and quorum sensing proteins. Eight clusters having two LanM determinants, similar to haloduracin and lichenicidin were identified, along with 13 clusters having a single LanM determinant as in mersacidin biosynthetic cluster. Besides these, orphan LanT homologs were also identified which might be associated with novel bacteriocins, encoded somewhere else in the genome. Three identified gene clusters had a C39 domain containing LanT transporter, associated with the LanBC proteins and double glycine type precursor peptides, the only known example of such a cluster is that of salivaricin. CONCLUSION: This study led to the identification of 8 novel putative two-component lantibiotic clusters along with 13 having a single LanM and 3 with LanBC genes. Putative lantibiotic clusters identified here hold the potential for the discovery of novel lantibiotic(s).

Pretreatment of Cr(VI)-amended soil with chromate-reducing rhizobacteria decreases plant toxicity and increases the yield of Pisum sativum.

Pot culture experiments were performed under controlled greenhouse conditions to investigate whether four Cr(VI)-reducing bacterial strains (SUCR44, SUCR140, SUCR186, and SUCR188) were able to decrease Cr toxicity to Pisum sativum plants in artificially Cr(VI)-contaminated soil. The effect of pretreatment of soil with chromate-reducing bacteria on plant growth, chromate uptake, bioaccumulation, nodulation, and population of Rhizobium was found to be directly influenced by the time interval between bacterial treatment and seed sowing. Pretreatment of soil with SUCR140 (Microbacterium sp.) 15 days before sowing (T+15) showed a maximum increase in growth and biomass in terms of root length (93 %), plant height (94 %), dry root biomass (99 %), and dry shoot biomass (99 %). Coinoculation of Rhizobium with SUCR140 further improved the aforementioned parameter. Compared with the control, coinoculation of SUCR140+R showed a 117, 116, 136, and 128 % increase, respectively, in root length, plant height, dry root biomass, and dry shoot biomass. The bioavailability of Cr(VI) decreased significantly in soil (61 %) and in uptake (36 %) in SUCR140-treated plants; the effects of Rhizobium, however, either alone or in the presence of SUCR140, were not significant. The populations of Rhizobium (126 %) in soil and nodulation (146 %) in P. sativum improved in the presence of SUCR140 resulting in greater nitrogen (54 %) concentration in the plants. This study shows the usefulness of efficient Cr(VI)-reducing bacterial strain SUCR140 in improving yields probably through decreased Cr toxicity and improved symbiotic relationship of the plants with Rhizobium. Further decrease in the translocation of Cr(VI) through improved nodulation by Rhizobium in the presence of efficient Cr-reducing bacterial strains could also decrease the accumulation of Cr in shoots.

Primary duodenal tuberculosis presenting as gastric-outlet obstruction: Its diagnosis.

INTRODUCTION: Gastrointestinal tuberculosis often involves the ileocecal region. Duodenal and gastric tuberculosis found in only 1% of patients suffering from pulmonary tuberculosis with associated HIV infection in non-endemic areas. Duodenal obstruction due to tuberculosis is very rare and needs high index of suspicions for diagnosis. Mostly this entity is suspected on intraoperative findings. In this manuscript we emphasized on ways and means for establishing histopathological diagnosis before starting anti-tubercular treatment in such cases. METHOD AND MATERIAL: All patients of suspected gastroduodenal tuberculosis presented with feature of gastric-outlet obstruction managed during Jan 2009 to June 2011 were included in the study. After proper evaluation (routine hematological and biochemical examination, microbiological examination, serological and endoscopic evaluation) exploratory laparotomy was done and if there is no mesenteric lymphadenopathy or it is not safe to take biopsy form the diseased duodenum, multiple FNAC were taken from the diseased portion for histopathological and microbiological diagnosis. RESULT: A total of five patients were treated during this period. The most common presentation was vomiting followed by failure to thrive and weight loss; two patients had abdominal pain. Biopsy of mesenteric lymph node was possible in two cases. FNAC from diseases portion was taken in all cases. FNAC showed granulomas in four cases. Cases where even FNAC finding was non-conclusive on HPE/Microbiology was not subjected to antitubercular drug. CONCLUSION: Multiple intra-operative FNAC may be taken from the diseased portion of the duodenum to establish the histopathological diagnosis if diagnosis is not established by any other mean.

Spontaneous biliary peritonitis: Is bed side diagnosis possible?

BACKGROUND: Spontaneous biliary peritonitis is a rare cause of acute abdomen. In spontaneous biliary peritonitis there is perforation in the wall of the extra-hepatic or intra-hepatic duct occurs without any traumatic or iatrogenic injury and have been described more often in neonates. The symptoms may be acute or insidious delaying the diagnosis. Present manuscript deals with diagnosis and management of these cases. MATERIALS AND METHODS: This is a prospective study and all patients of suspected biliary peritonitis presented during Dec 2010 to Feb 2012 were included in the study. After preliminary investigations in all patients abdominal paracentesis was done and in cases where intra-abdominal fluid bilirubin level was several fold higher than serum bilirubin level were subjected to exploratory laparotomy. Further investigation like T-tube cholangiogram and magnetic resonance cholangiopancreatography (MRCP) was done to rule out choledochal cyst before leveling these cases as SPBD. RESULTS: A total of 6 patients were included in present series commonest presenting symptom was progressive abdominal distension without signs of overt peritonitis followed by progressive jaundice, fever and abdominal pain. On exploration site of perforation was observed in 50% of cases and in 50% of cases bile duct was not dilated. Second surgery was not required in 34% of cases. There was no mortality or significant morbidity in our series. CONCLUSION: Spontaneous perforation of bile duct is rare disease and high index of suspicion is required for diagnosis. Simple bed side test can help in diagnosis but T tube cholangiogram or MRCP are must to rule out choledochal cyst.

In vitro Cr(VI) reduction by cell-free extracts of chromate-reducing bacteria isolated from tannery effluent irrigated soil.

Four efficient Cr(VI)-reducing bacterial strains were isolated from rhizospheric soil of plants irrigated with tannery effluent and investigated for in vitro Cr(VI) reduction. Based on 16S rRNA gene sequencing, the isolated strains SUCR44, SUCR140, SUCR186, and SUCR188 were identified as Bacillus sp. (JN674188), Microbacterium sp. (JN674183), Bacillus thuringiensis (JN674184), and Bacillus subtilis (JN674195), respectively. All four isolates could completely reduce Cr(VI) in culture media at 0.2 mM concentration within a period of 24-120 h; SUCR140 completely reduced Cr(VI) within 24 h. Assay with the permeabilized cells (treated with Triton X-100 and Tween 80) and cell-free assay demonstrated that the Cr(VI) reduction activity was mainly associated with the soluble fraction of cells. Considering the major amount of chromium being reduced within 24-48 h, these fractions could have been released extracellularly also during their growth. At the temperature optima of 28 °C and pH 7.0, the specific activity of Cr(VI) reduction was determined to be 0.32, 0.42, 0.34, and 0.28 µmol Cr(VI)min(-1)mg(-1) protein for isolates SUCR44, SUCR140, SUCR186, and SUCR188, respectively. Addition of 0.1 mM NADH enhanced the Cr(VI) reduction in the cell-free extracts of all four strains. The Cr(VI) reduction activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg(2+). Beside this, urea and thiourea also reduced the activity of chromate reduction to significant levels.

Autofluorescence--an important ancillary technique for the detection of Mycobacterium tuberculosis: revisited.

Tuberculosis is one of the oldest diseases known to affect humans and is caused by Mycobacterium tuberculosis. Lymph nodes are the most common site of extrapulmonary involvement. Tuberculous lymphadenitis can be presumptively diagnosed morphologically on fine-needle aspiration biopsy of lymph nodes. Additional tests like Ziehl-Neelsen (ZN) stain for detection of acid fast bacilli, fluorescence, and molecular markers are often employed for confirmation of diagnosis. However, culture is essential for obtaining a definitive diagnosis. Unfortunately, culture is time consuming and expensive. Newer investigative methods are required. The efficacy of autofluorescence in the diagnosis of tuberculous lymphadenitis was evaluated for this purpose. Fine-needle aspiration biopsies were collected from patients with a clinical diagnosis of tuberculous lymphadenitis. Cytomorphological examination, ZN staining, autofluorescence, and culture were performed on all specimens. ZN staining was positive in 37.5% (30/80) of cases, while autofluorescence was positive in 57.5% (46/80) of patients and was found to have 81.8% specificity, 95% sensitivity, and a positive predictive value of 82.6%. This technique allowed rapid and early diagnosis of tuberculous lymphadenitis in a number of patients, permitting early institution of appropriate therapy.

Biochemical characterization of consortium compost of toxic weeds Parthenium hysterophorus and Eichhornia crassipe.

Parthenium hysterophorus and Eichhornia crassipes are two uncontrolled weeds with high concentration of N, P, K, Zn and Fe that makes them suitable for composting. Three types of compost viz. Parthenium and Eichhornia each alone as well as combined were prepared. Biochemical and enzymatic analysis of the compost in addition to seed germination was performed. Phenols, organic carbon, C/N and C/P ratios were found to decrease significantly while N, P, K, polyphenol oxidase increased significantly in combined compost. Furthermore, seed germination test of Vigna radiata and Triticum seeds, revealed a significant increase in root, shoot length and germination index in 60days old combined compost. It can be concluded that combined composting of Parthenium with Eichhornia not only reduces the allelopathic effect but also increases its nutrient quality and thus could be promising for organic farming and bioremediation.

Role of functional polymorphism of matrix metalloproteinase-2 (-1306 C/T and -168 G/T) and MMP-9 (-1562 C/T) promoter in oral submucous fibrosis and head and neck squamous cell carcinoma in an Indian population.

The aim of this study was to explore the association of MMP-2 (-1306 C/T and -168 G/T) and MMP-9 (-1562 C/T) promoter polymorphisms in oral submucous fibrosis (OSMF) and head and neck squamous cell carcinoma (HNSCC) cases. These SNP were genotyped by PCR-RFLP. Total of 1260 individuals were recruited, of which 412 OSMF, 422 HNSCC and 426 were controls. In HNSCC, MMP-2 (-1306 C/T) and MMP-9 (-1562C/T) polymorphism, T allele showed strong association (p < 0.00 and p < 0.01) as compared to healthy control respectively, but not in case of OSMF and showed significant association with increasing progression of clinico-pathological grading. We concluded that SNPs in the MMP-2 and -9 promoter region may be associated with susceptibility to HNSCC not in OSMF.

The efficacy of oral brush biopsy with computer-assisted analysis in identifying precancerous and cancerous lesions.

BACKGROUND: Cancer of the oral cavity is the sixth most common malignancy reported worldwide and one with the highest mortality rate among all malignancies. There is a paucity of reliable diagnostic methods to detect early malignancies. This study was performed to evaluate the sensitivity and specificity of brush biopsy in identifying oral premalignant and malignant lesions. METHODS: Oral brush and scalpel biopsies were performed on 85 consecutive patients presenting with an oral lesion deemed to be minimally suspicious by clinical examination and the results were compared. RESULTS: Of 79 patients with adequate brush biopsy samples with matching scalpel biopsies, 27 revealed histopathologic evidence of dysplasia or carcinoma, 26 of which were independently identified with the oral brush biopsy (sensitivity: 96.3%-95% CI, 87%-100%). 52 oral lesions did not reveal any histopathologic evidence of dysplasia or carcinoma and of these, brush biopsy reported 47 as "negative" and 5 as "atypical"(specificity of "positive" brush biopsy result is 100%- 95% CI, 93%-100%; specificity for "atypical" brush biopsy result is 90.4%-95% CI, 82%-97%. The positive predictive value of an abnormal oral brush biopsy was 84% and the negative predictive value was 98%. CONCLUSION: Our study demonstrated that the oral brush biopsy is an accurate test in identifying oral premalignant and malignant lesions, even if minimally suspicious.