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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