bio 120 journal report

7/29/2019 Bio 120 Journal Report

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Susceptibility Profile of Methicillin-

Resistant Staphylococcus aureus(MRSA) Isolates to Antibiotics and

Methanolic Extracts ofParkia

biglobosaA. F. Obajuluwa, J. A. Onaolapo, A. R. Oyi1 and B. O. Olayinka


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Purpose of the Study

To study the susceptibility profile of methicillin-resistant

Staphylococcus aureus (MRSA) isolates from orthopaedic

patients to antibiotics and methanolic extracts ofParkia

biglobosa


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Staphyloccocus Gram-positive cocci

Facultative aerobes

Produce acid from glucose

both aerobically and

anaerobically

Resistant to drying Tolerate high salt

concentrations

Forms cell clusters

Normal microbial flora of

upper respiratory tract

Noses, Mouth and Skin

Common parasites of

humans and animals

Cause serious infections


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2 Major Species of

Staphylococcus

Staphylococcusepidermidis

Nonpigmented,

nonpathogenic organism

Found on skin or

mucous membranes

Staphylococcusaureus

Yellow-pigmented

organisms

Associated with

pathological conditions

like pimples, meningitis,

arthritis, etc.


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Staphylococcus aureus


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Staphylococcus aureusAble to resist the effects of an antimicrobial agent (methicillin) towhich it is normally susceptible

Methicillin-resistant Staphylococcus aureus was first discoveredin 1961, they were isolates of S. aureus which have acquiredgenes encoding antibiotic resistance to all penicillins includingmethicillin and other narrow spectrum beta-lactamase resistant

penicillin antibiotics.

Methicillin

semi-synthetic penicillin

Acid-stable

Action: inhibit cell wall synthesis by blocking transpeptidation

(cross-linking of two glycan-linked peptide chains)Transpeptidase enzymes bind to penicillin -> penicillin-bindingproteins: cannot catalyze transpeptidase reaction but cell wallsynthesis continues -> formation of bacterial cell wall that is notcross-link and cannot maintain its strength


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Staphylococcus aureus

Widespread hospital pathogen

Pneumonia, Blood infections, Food poisoning, Carditis,Meningitis, Arthritis, Acne, Boils, Pimples

Infections occur when resistance of host is low because ofhormonal changes, illnesses, wounds or treatment with drugsthat compromise immunity

Most individuals are carriers, and infections can be transmittedby simple contact: prevention is hard

Resistant to common antibiotics like penicillin-> treatment isvery difficult

Problem: Search for alternative anti-staphylococcalagents


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Susceptibility Profile of Methicillin-Resistant

Staphylococcus aureus (MRSA) Isolates to

Antibiotics and Methanolic Extracts ofParkiabiglobosa

Staphylococcal isolates from wound, skin and bed swab

samples from orthopedic patients in Nigeria Delay in the union of fractured bones

Parkia biglobosa: the African locust bean tree


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Parkia biglobosa

Occur in agroecologicalzones from tropicalrainforest where rain is highto arid zone where rain islow

Bark used as mouthwash,vapour inhalant fortoothache, ear complaints

Extract used for leprosy,bronchitis, pneumonia,sores, etc.

Leaves and roots used inlotion for sore eyes,hemorrhoids, toothache

Seed taken for tension andpulp for fevers


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MethodologySuspected staphylococcal

isolates: wound, skin and bedswabs

Detection of MethicillinResistance: isolates were spot-inoculated onto MHA agar with6g/mL methicillin: isolates with

growth are methicillin resistant

Antibiotic Sensitivity Test: KirbyBauer-NCCLS (modified discagar diffusion technique)

Isolates on NA plates w/ 3mLphosphate buffer solution and

turbidity adjusted to .5 McFarlandstandard

MHA plate inoculated withbacterial suspension by streakingin 3 directions and was allowed todry

Antibiotic discs were applied:methicillin, ampicillin,

vancomycin, oxacillin, gentamicin,ceftriaxone, pefloxacin and

Collection and Authentication of

Parkia biglobosa: leaves, rootsand stem bark samples were airdried, ground into powder andwas extracted using soxhletapparatus for methanol: solventwas then removed andmethanolic extract was stored indesiccator until used


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Methodology

Phytochemical Screening: presence ofsaponins, tannins, flavonoids,carbohydrates, alkaloids and steroids

Plant chemicals that have protective ordisease preventive properties

Antibacterial Activity of Crude MethanolicExtract of Leaves, Roots and Stem Barkof Parkia biglobosa to MRSA isolates:

Overnight broth culture of each isolatewas inoculated at MHA medium at45*C, allowed to set, wells were madeusing standard cork borer and various

concentrations of plant extract wereadded to each well

Plates were allowed to stand at roomtemp for 1 hr and incubated at 37*C for24 hrs. Diameter of each zone ofinhibition was measured afterincubation.


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Results


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Phytochemical screening


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Leaves


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Roots


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Stem Bark


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Anti-staphylococcalproperties

ofParkia biglobosa

Stem bark showed the greatest activity against MRSAisolates

Rich in flavonoids, tannins and saponins

Secondary metabolites that have antibacterial activitiesOrganic compounds formed near the end of growth so they arenonessential for growth and reproduction

Often overproduced

Some roles:

Protective agents (antioxidants, UV light absorbing, freeradical-scavenging)

Defend plants against microbes

Feeding deterrence: toxicity of phytochemicals


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Anti-staphylococcalproperties

ofParkia biglobosa

Secondary Metabolites found in Parkia biglobosa

Stem bark rich in sterols, triterpenes, tannins, saponosides,

anthocyanins, flavonoids, coumarins and reducing

compounds

Leaf rich in tannins, coumarins, anthocyanins, flavones and

reducing compounds

Root contains saponins, glycosides, tannins and a trace of

alkaloids

These metabolites may be responsible for the observed

antibacterial activities


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END(or staph-ylococcus)


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References

Microbiology, An Introduction 10th Ed by Tortora, Funke,

Case

Brock Biology of Microorganisms 13th Ed by Madigan,

Martinko Stahl, Clark

Phytochemicals: http://www.opc-1-2-3.com/antioxidant-

phytochemicals.html

Secondary Metabolites:http://advances.nutrition.org/content/2/1/32.full

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