Antibacterial Property of Different Medicinal Plants: Ocimum sanctum, Cinnamomum zeylanicum, Xanthoxylum armatum and Origanum majorana

Countries like Nepal and India have been using crude plants as medicine since Vedic period. A major part of the total population in developing countries still uses traditional folk medicine obtained from plant resources (Farnsworth 1994). With an estimation of WHO that as many as 80% of worlds population living in rural areas rely on herbal traditional medicines as their primary health care, the study on properties and uses of medicinal plants are getting growing interests. In recent years this interest to evaluate plants possessing antibacterial activity for various diseases is growing (Clark and Hufford, 1993). Based on local use of common diseases and Ethnobotanical knowledge, an attempt has been made to assess the antibacterial properties of selected medicinal plants.VIZ. Ocimum sanctum (Tulsi), Origanum majorana (Ram Tulsi), Cinnamomum zeylanicum (Dalchini), and Xanthoxylum armatum (Timur), for potential antibacterial activity against 10 medically important bacterial strains, namely Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Staphylococcus aureus, Pseudomonas spp, Proteus spp, Salmonella Typhi, Escherichia coli, Shigella dysentriae, Klebsiella pneumoniae. The antibacterial activity of ethanol extracts was determined by agar well diffusion method. The plant extracts were more active against Gram-positive bacteria than against Gram-negative bacteria. The most susceptible bacteria were B. subtilis, followed by S. aureus, while the most resistant bacteria were E.coli, followed by Shigella dysenteriae, Klebsiella pneumoniae and Salmonella typhi. From the screening experiment, Origanum majorana showed the best antibacterial activity; hence this plant can be further subjected to isolation of the therapeutic antimicrobials and pharmacological evaluation. The largest zone of inhibition was obtained with Xanthoxylum armatum against Bacillus subtilis (23mm) and the minimum bactericidal concentration (MBC) value of 2.5 mg/l was obtained. Key words: Antibacterial property; Gram positive bacteria; Gram negative bacteria; zone of inhibition; minimum bactericidal concentration DOI: 10.3126/kuset.v5i1.2854 Kathmandu University Journal of Science, Engineering and Technology Vol.5, No.1, January 2009, pp 143-150

Extended spectrum β-lactamase producing uropathogenic Escherichia coli and the correlation of biofilm with antibiotics resistance in Nepal

BACKGROUND

Urinary tract infection (UTI) is one of the frequently diagnosed infectious diseases which is caused mainly by Escherichia coli. E. coli confers resistance against the two major classes of antibiotics due to the production of extended spectrum β-lactamase enzymes (ESBL), biofilm, etc. Biofilm produced by uropathogenic E. coli (UPEC) protects from host immune system and prevent entry of antimicrobial compounds. The main objective of this cross-sectional study was to determine the correlation of biofilm production and antibiotic resistance as well as to characterize the pgaA and pgaC genes responsible for biofilm formation among uropathogenic ESBL producing E. coli.

METHODS

A total of 1977 mid-stream urine samples were examined and cultured for bacterial strain identification. ESBL was detected by combined disc method following CLSI whereas biofilm formation was analyzed by semi-quantitative method. Furthermore, the pgaA and pgaC genes responsible for biofilm formation in UPEC were detected by multiplex PCR. All the statistical analyses were done via IBM SPSS Statistics 21 where Pearson's correlation test were used to determine correlation (-1 ≥ r ≤ 1).

RESULTS

E. coli was the predominant causative agent, which accounted 159 (59.3%) of the Gram-negative bacteria, where 81 (50.9%) E. coli strains were found to be ESBL producers. In addition, 86 (54.1%) E. coli strains were found to be biofilm producers. Both the pgaA and pgaC genes were detected in 45 (93.7%) the UPEC isolates, which were both biofilm and ESBL producers. Moreover, there was a positive correlation between biofilm and ESBL production.

CONCLUSION

The analyses presented weak positive correlation between biofilm and ESBL production in which biofilm producing UPEC harbors both pgaA and pgaC genes responsible for biofilm formation.

Evaluation of multiplex PCR using MPB64 and IS6110 primers for rapid diagnosis of tuberculous meningitis

Tuberculous meningitis (TBM) is one of those most serious manifestations of extra-pulmonary tuberculosis and prompt diagnosis and treatment is required for better clinical outcome. It is difficult to diagnose due to lack of rapid, sensitive, and specific tests. Newer methods, which are easy and reliable, are required to diagnose TBM at an early stage. Thus our aim was to evaluate the Multiplex polymerase chain reaction (PCR) technique, using primers directed against the insertion sequence IS6110 and MPB64 gene for the detection of Mycobacterium tuberculosis in Cerebrospinal fluid (CSF), for rapid diagnosis of TBM patients. 102 CSF samples were analyzed from patients suspected with TBM along with a control group of 10 patients having other neurological disorders. CSF sediments were analyzed individually for M. tuberculosis DNA by Multiplex PCR using two set of primers targeting insertion sequence IS6110 and gene MBp64, which is very specific for MTBC. Out of 37 patients diagnosed with TBM clinically, MPB64 PCR was positive in 22, IS6110 PCR was positive in 28, both PCR using Multiplex were positive in 34 and Microscopy was positive in one. Thus Sensitivity of MPB64 PCR, IS6110 PCR, Multiplex PCR and Microscopy were found to be 62.3%, 75.4%, 91.8% and 2.7% respectively. In non TBM group PCR was negative in all cases hence, the specificity was 100%. Multiplex PCR system using primers targeting IS6110 and MPB64, for the detection of M. tuberculosis DNA in CSF samples, has high sensitivity than any one of them alone, and could be used for the early detection of TBM in CSF samples.

Preparatory phase for clinical trials of COVID-19 vaccine in Nepal

Public health data suggested a rapid rise in COVID-19-confirmed cases in Nepal along with increased deaths. There has been a wide variation in clinical outcomes of this disease. Control of this pandemic depends on the availability of vaccines or drugs for SARS-CoV-2. Thus, viral and human genetics/genomics and immunology are necessary to understand whether these factors will affect clinical trials of vaccines in Nepal.

Emergence of mcr-1 Gene in Colistin-Resistant Escherichia coli Isolates from Chicken in Chitwan, Nepal

The escalating prevalence of colistin-resistant Escherichia coli in poultry has emerged as a significant concern. This study aimed to assess the occurrence of the mcr-1 gene in colistin-resistant E. coli isolates from poultry samples. A cross-sectional study was conducted at National Avian Disease Investigation Laboratory, Nepal, on 210 chicken meat samples, including liver, heart, and spleen. E. coli was isolated and identified by conventional cultural methods. Antibiotic resistance pattern was assessed by the Kirby-Bauer disc diffusion method. The mcr-1 gene was detected by conventional polymerase chain reaction. The average viable count in chicken meat samples was log 6.01 CFU (colony-forming unit)/g, whereas the average coliform count was log 3.85 CFU/g. Coliforms were detected in at least one sample from 48.01% of total samples. The prevalence of E. coli in all meat samples was 39.52%. Liver accounted for the largest fraction of E. coli isolates (45.45%). Cefepime was the most effective antibiotic. Among all isolates, 45 (54.21%) were multidrug-resistant E. coli, 17 (20.48%) were colistin-resistant E. coli, and 11 (64.70%) harbored the mcr-1 gene. High prevalence of multidrug-resistant E. coli isolates, colistin-resistant isolates, and mcr-1 gene-carrying isolates indicates a serious concern, as it could potentially lead to colistin resistance in human pathogens through horizontal transfer of resistant genes from poultry to humans.

Inducible Clindamycin Resistance and Biofilm Production among Staphylococci Isolated from Tertiary Care Hospitals in Nepal

Resistance to antibiotics, biofilm formation and the presence of virulence factors play important roles in increased mortality associated with infection by staphylococci. The macrolide lincosamide streptogramin B (MLS_B) family of antibiotics is commonly used to treat infections by methicillin-resistant isolates. Clinical failure of clindamycin therapy has been reported due to multiple mechanisms that confer resistance to MLS_B. This study aims to find the incidence of different phenotypes of MLS_B resistance and biofilm production among staphylococci. A total of 375 staphylococci were isolated from different clinical samples, received from two tertiary care hospitals in Nepal. Methicillin resistance was detected by cefoxitin disc diffusion method and inducible clindamycin resistance by D test, according to CLSI guidelines. Biofilm formation was detected by the tissue culture plate method and PCR was used to detect ica genes. Of the total staphylococci isolates, 161 (42.9%) were Staphylococcus aureus, with 131 (81.4%) methicillin-resistant strains, and 214 (57.1%) isolates were coagulase-negative staphylococci, with 143 (66.8%) methicillin-resistant strains. The overall prevalence of constitutive MLS_B (cMLS_B) and inducible MLS_B (iMLS_B) phenotypes was 77 (20.5%) and 87 (23.2%), respectively. Both iMLS_B and cMLS_B phenotypes predominated in methicillin-resistant isolates. The tissue culture plate method detected biofilm formation in 174 (46.4%) isolates and ica genes in 86 (22.9%) isolates. Among biofilm producing isolates, cMLS_B and iMLS_B phenotypes were 35 (20.1%) and 27 (15.5%), respectively. The cMLS_B and iMLS_B were 11 (12.8%) and 19 (22.1%), respectively, in isolates possessing ica genes. Clindamycin resistance in the form of cMLS_B and iMLS_B, especially among MRSA, emphasizes the need for routine D tests to be performed in the lab.