Bacterial infections caused by
The thirteen edible plants were collected from different localities of Cameroon, namely, Obala (Centre Region), Muyuka (South-West Region), and Dschang (West Region) from March to April 2016. The collected plant samples included the bark of
Information on the studied plants.
Species (family); voucher number | Traditional uses | Bioactive or potentially bioactive components | Known antimicrobial activities of plants |
---|---|---|---|
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Antimalarial, anticancer, anti-inflammatory, antidiabetic, antihyperglycaemic, antiulcerous [ |
Alkaloids, glycosides, flavonoids, and saponins [ |
Antibacterial activity of ethanol leaf extract: |
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Cancer [ |
Alkaloids, cardioglycosides, saponins, tannins, terpenoids, flavonoids, and steroids [ |
Antibacterial activity of petroleum ether, ethyl acetate, chloroform, ethanol, and leaf water: |
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Diabetes, cancer, antihypertensive, anti-inflammatory, immunomodulating, and bacterial infections [ |
Tannins, saponins, alkaloids [ |
Antibacterial activity of aqueous seed extract: |
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Gastrointestinal disorders, toothache, earache [ |
Ethyl gallate and quercitrin [ |
Antibacterial activity of hydromethanolic, butanol, aqueous, ethanolic extract, ethyl acetate of bark: |
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Inflammation, pain [ |
Not reported | Not reported |
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Antidiabetic, anti-inflammatory, reducing risk of cardiovascular disease, anticancer, reducing stomach stress, nausea, diarrhea [ |
Caffeoylquinic acid [ |
Not reported |
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Diarrhea, hernia, yellow fever, dysentery, antipoison [ |
Saponins, tannins, phenols, and phlobatannins [ |
Antibacterial activity of aqueous and ethanol extract of leaves and bark: |
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Antioxidant [ |
Alkaloids, steroids, and flavonoids [ |
Antibacterial activity of aqueous, alcohol, chloroform, ether extract of seeds: |
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Cough, antidote, intestinal diseases [ |
Tannins, polyphenols, alkaloids, glycosides, flavonoids, steroids, and saponins [ |
Antibacterial activity of methanol extract of the leaves: |
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Jaundice and liver problems, hemorrhoids, dysentery, menorrhagia [ |
Flavonoids, saponins, tannins, and alkaloids [ |
Antibacterial activity of methanol extract of the stems: |
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Diuretic, febrifuge, diarrheal diseases, dysentery, hemorrhoids, gonorrhea, leucorrhea [ |
Saponins, tannins, flavonoids, alkaloids, and glycosides [ |
Antibacterial activity of ethanol, methanol, water, and acetone extracts of the leaves: |
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Cardiovascular, gastrointestinal, and nervous diseases [ |
Alkaloids, anthraquinones, cardiac glycosides, and saponins [ |
Antibacterial activity: |
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Leprosy, epilepsy, edema, rheumatism, aphrodisiac, fever, inflammation, absorption [ |
Steroids, alkaloid, terpenoids, and gallic acid [ |
Not reported |
HNC: Herbier National du Cameroun; SRFC: Société des Réserves Forestières du Cameroun; SRFK: Société des Réserves forestières du Kamerun; Af:
Eight reference antibiotics (RA) purchased from Sigma-Aldrich (St Quentin Fallavier, France) were tested: ampicillin (AMP), cefepime (CEF), chloramphenicol (CHL), ciprofloxacin (CIP), erythromycin (ERY), kanamycin (KAN), streptomycin (STR), and tetracycline (TET);
The strains of
Bacterial strains and features.
Bacteria | Features | References |
---|---|---|
ATCC 25923 | Reference strain | — |
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Clinical isolate: Met susceptible; Nisr, Chlr | [ |
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Clinical isolate: Ofxar, Kanr, Tetr, Ermr | [ |
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Clinical isolate: Ofxar, Kanr, Cypr, Chlr, Genr, Nisr, Ampr | [ |
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Clinical isolate: Ofxar, Flxr, Kanr, Tetr, Cypr, IM/Csr, Chlr, Genr, Nisr, Ampr | [ |
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Clinical isolate: Ofxar, Flxr, Kanr, Ermr, Cypr, Im/Csr, Chlr, Genr, Nisr, Ampr | [ |
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Clinical isolate: Ofxar, Flxr, Tetr, Ermr, Cypr, Im/Csr, Chlr, Genr, Nisr, Ampr | [ |
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Clinical isolate: Ofxar, Kanr, Ermr, Cypr, Im/Csr, Chlr, Nisr, Ampr | [ |
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Clinical isolate: Ofxar, Flxr, Kanr, Ermr, Im/Csr, Chlr, Genr, Nisr, Ampr | [ |
SA01 | Clinical isolate: Ermr, Ampr | [ |
SA07 | Clinical isolate: Ermr, Doxr | [ |
SA18 | Clinical isolate: Ampr, Doxr, Vmr | [ |
SA23 | Clinical isolate: Imir, Augr | [ |
SA36 | Clinical isolate: Doxr, Vmr | [ |
SA39 | Clinical isolate: Ampr | [ |
SA56 | Clinical isolate: Ampr, Doxr | [ |
SA64 | Clinical isolate: Ampr, Doxr | [ |
SA68 | Clinical isolate: Ampr, Vmr | [ |
SA88 | Clinical isolate: Ermr, Vmr | [ |
SA114 | Clinical isolate: Ampr, Doxr | [ |
SA116 | Clinical isolate: Ermr | [ |
SA124 | Clinical isolate: Ermr | [ |
SA126 | Clinical isolate: Ampr, Doxr | [ |
SA127 | Clinical isolate: Ampr, Doxr | [ |
SA135 | Clinical isolate: Ermr | [ |
SA139 | Clinical isolate: Ermr | [ |
Chlr, Cypr, Ermr, Flxr, Im/Csr, Kanr, Metr, Ofxar, Tetr, Vmr, Ampr, Doxr, Augr, Genr, and Nisr resistance to chloramphenicol, ciprofloxacin, erythromycin, flomoxef, imipenem/cilastatin sodium, kanamycin, methicillin, ofloxacin, tetracycline, vancomycin, ampicillin, doxycycline, augmentin, gentamicin, and nisin, respectively, SA:
Potential classes of potential antibacterial phytochemicals such as alkaloids (Dragendorff’s and Mayer’s tests: 5 mg plant extract in 10 mL methanol; a portion of 2 mL extract + 1% HCl + steam, 1 mL filtrate + 6 drops of Mayor’s reagents/Wagner’s reagent/Dragendorff’s reagent; cream precipitate/brownish-red precipitate/orange precipitate indicated the presence of respective alkaloids), saponins (frothing test: 0.5 mL filtrate+ 5 mL distilled water; frothing persistence indicated the presence of saponins), steroids and triterpenoids (Liebermann–Burchard test: 5 mg plant extract in 10 mL chloroform, filtered; a 2 mL filtrate + 2 mL acetic anhydride+ conc. H2SO4; blue-green ring or pink-purple indicated the presence of steroids or triterpenoids), phenolics: anthraquinones (5 mg plant extract in 10 mL methanol; a portion of 2 mL + 2 mL ether-chloroform 1 : 1 v/v + 4 mL NaOH 10% (w/v); red color indicated the presence of anthraquinones), flavonoids (5 mg plant extract in 10 mL methanol; a portion of 2 mL + conc. HCl + magnesium; ribbon pink-tomato red color indicated the presence of flavonoids), polyphenols (ferric chloride test: 5 mg plant material in 10 mL methanol; a portion of 2 mL + 2 mL FeCl3; violet-blue or greenish color indicated the presence of phenols), and tannins (5 mg plant extract in 10 mL distilled water; a portion of 2 mL + 2 mL FeCl3; blue-black precipitate indicated the presence of tannins) (Table
Extraction yields and phytochemical composition of the plant extracts.
Plant extract and part used | Yields (%) | Alkaloids | Polyphenols | Flavonoids | Anthraquinones | Tannins | Triterpenes | Steroids | Saponins | |
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Bark | 10.3 | + | + | − | − | + | − | + | + |
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Leaves | 2.6 | + | + | − | − | + | + | + | − |
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Beans | 2.6 | − | + | − | − | + | + | + | + |
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Leaves | 6.2 | − | + | + | + | + | + | + | + |
Bark | 9.1 | − | + | − | + | + | + | + | + | |
Seeds | 6.9 | − | + | + | + | + | + | + | + | |
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Leaves | 1.9 | − | + | − | − | + | − | + | − |
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Beans | 3.3 | + | + | + | + | + | + | − | + |
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Leaves | 6.7 | − | + | − | − | + | − | + | + |
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Leaves | 1.2 | − | + | − | − | + | − | + | + |
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Bark | 2.9 | − | + | + | + | + | + | + | − |
Leaves | 7.2 | − | + | + | + | + | + | + | + | |
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Leaves | 21.4 | − | + | − | − | + | + | + | − |
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Leaves | 8.4 | − | + | − | − | + | − | + | + |
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Leaves | 3.1 | − | + | − | − | + | + | + | + |
Beans | 6.2 | + | + | + | + | + | + | + | + | |
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Leaves | 7.3 | − | + | − | − | + | + | + | + |
Bark | 6.1 | + | + | − | − | + | + | + | + |
−: absent; +: present; yield calculated as the ratio of the mass of the obtained methanol extract/mass of the plant powder.
The MIC and minimal bactericidal concentration (MBC) determinations on various strains of
To evaluate the involvement of efflux pumps in the resistance of selected bacterial strains to some of the active plant extracts,
To evaluate the antibiotic resistance modulation activity of the most active extracts:
The major classes of phytochemicals were screened in the 18 studied plant extracts (Table
The antibacterial activities of the 18 tested extracts and ciprofloxacin against 26 strains of
MIC and MBC of the plant extracts and ciprofloxacin against
Bacterial strainsa | Samplesb, MIC and MBC in | ||||||||||||||||||
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Plant extracts | Antibiotic | ||||||||||||||||||
AIB | CGL | CMB | DES | DEB | DEL | HEL | IBL | IGB | PVL | RHB | RHL | SML | SOL | TCB | TCL | UGL | UGB | CIP | |
ATCC 25923 | 1024 (–) | – | – | 1024 (–) | 512 (–) | 1024 (–) | – | – | – | 512 (–) | 1024 (–) | 512 (–) | – | 1024 (–) | – | – | – | – | <0.5 (16) |
SA01 | 512 (–) | 1024 (–) | – | 512 (–) | 512 (–) | 512 (–) | 512 (–) | – | – | 512 (–) | – | 512 (–) | – | 1024 (–) | 512 (–) | – | 512 (–) | 512 (–) | <0.5 (4) |
SA07 | 1024 (–) | – | – | 512 (–) | 512 (–) | 512 (–) | 512 (–) | 1024 (–) | – | 1024 (–) | – | 512 (–) | – | 1024 (–) | – | – | 512 (–) | – | <0.5 (1) |
SA18 | 512 (1024) | 1024 (–) | – | 512 (–) | 512 (–) | 512 (–) | 512 (–) | – | 1024 (–) | 512 (–) | 1024 (–) | 512 (–) | – | 512 (–) | 512 (–) | – | 512 (–) | 1024 (–) | <0.5 (8) |
SA23 | 1024 (–) | 512 (–) | – | 512 (–) | 512 (–) | 1024 (–) | 512 (–) | 1024 (–) | 1024 (–) | 512 (–) | 1024 (–) | 512 (–) | 1024 (–) | 1024 (–) | 512 (–) | 512 (–) | 512 (–) | 512 (–) | <0.5 (<0.5) |
SA36 | 512 (–) | – | 1024 (–) | 256 (1024) | 1024 (–) | 1024 (–) | 512 (–) | 1024 (–) | – | 1024 (–) | 512 (–) | 512 (–) | 1024 (–) | 1024 (–) | 1024 (–) | – | 512 (–) | 512 (–) | 1 (8) |
SA39 | 1024 (–) | 1024 (–) | – | 512 (–) | 1024 (–) | 1024 (–) | 1024 (–) | – | – | 1024 (–) | 1024 (–) | – | 1024 (–) | – | – | 512 (–) | 512 (–) | 512 (–) | <0.5 (16) |
SA56 | 1024 (–) | – | – | 1024 (–) | 1024 (–) | 1024 (–) | 1024 (–) | – | 1024 (–) | 512 (–) | – | 512 (–) | – | 1024 (–) | – | – | – | 1024 (–) | <0.5 (4) |
SA64 | 512 (–) | 512 (–) | 1024 (–) | 512 (–) | 1024 (–) | 512 (–) | 512 (–) | 1024 (–) | – | 512 (–) | 256 (–) | 1024 (–) | 1024 (–) | – | – | 1024 (–) | 512 (–) | 1024 (–) | 4 (8) |
SA68 | 1024 (–) | – | – | 1024 (–) | 1024 (–) | 1024 (–) | 1024 (–) | 1024 (–) | – | 1024 (–) | 1024 (–) | 512 (–) | – | – | 1024 (–) | – | – | – | <0.5 (<0.5) |
SA88 | 512 (–) | 1024 (–) | 1024 (–) | 512 (–) | 1024 (–) | 1024 (–) | 512 (–) | 1024 (–) | – | 512 (1024) | – | 512 (–) | – | 1024 (–) | 1024 (–) | 1024 (–) | 1024 (–) | 1024 (–) | <0.5 (2) |
SA114 | 1024 (–) | – | – | 1024 (–) | 1024 (–) | 1024 (–) | 256 (–) | 512 (–) | – | 512 (–) | 512 (–) | – | 1024 (–) | 1024 (–) | – | 512 (–) | 512 (–) | 512 (–) | <0.5 (<0.5) |
SA116 | – | 1024 (–) | – | 512 (–) | 1024 (–) | 512 (–) | 512 (–) | – | 1024 (–) | 1024 (–) | – | 1024 (–) | 1024 (–) | 1024 (–) | – | – | 512 (–) | – | <0.5 (<0.5) |
SA124 | – | 1024 (–) | – | 512 (–) | 1024 (–) | – | – | 1024 (–) | – | – | – | 1024 (–) | – | – | – | 512 (–) | – | – | <0.5 (<0.5) |
SA126 | 1024 (–) | – | 1024 (–) | 512 (–) | 512 (–) | 1024 (–) | 512 (–) | 1024 (–) | – | 1024 (–) | 1024 (–) | 1024 (–) | – | – | – | 1024 (–) | 1024 (–) | – | <0.5 (<0.5) |
SA127 | 512 (–) | – | – | 1024 (–) | 1024 (–) | 1024 (–) | 512 (–) | 1024 (–) | – | 512 (1024) | – | 1024 (–) | 1024 (–) | – | – | – | – | – | <0.5 (<0.5) |
SA135 | 1024 (–) | – | – | 512 (1024) | 1024 (–) | 1024 (–) | 1024 (–) | – | – | 1024 (–) | – | 512 (–) | – | 1024 (–) | – | – | – | – | <0.5 (1) |
SA139 | 512 (–) | – | – | 512 (–) | 512 (–) | – | 1024 (–) | 1024 (–) | – | 512 (–) | 1024 (–) | 512 (–) | – | 1024 (–) | – | 1024 (–) | – | 1024 (–) | <0.5 (<0.5) |
MSSA1 | 512 (–) | – | 256 (512) | 512 (1024) | 1024 (–) | 256 (–) | 512 (1024) | 1024 (–) | – | 512 (–) | 256 (1024) | 512 (1024) | – | 1024 (–) | 256 (–) | 512 (–) | 256 (1024) | 128 (1024) | 2 (16) |
MRSA3 | 512 (1024) | 1024 (–) | 256 (–) | 512 (1024) | 1024 (–) | 512 (–) | 1024 (–) | – | 1024 (–) | 512 (–) | 256 (–) | 1024 (–) | 512 (–) | – | 256 (–) | 256 (–) | 256 (–) | 128 (–) | 2 (16) |
MRSA4 | 512 (–) | 512 (–) |
|
512 (512) | 512 (1024) | 256 (–) | 1024 (–) | 1024 (–) | – | 128 (–) | 128 (–) | 1024 (–) | 1024 (–) | 1024 (–) | 256 (–) | 512 (–) | 256 (–) | 256 (–) | 1 (16) |
MRSA6 | 512 (–) | 512 (–) | 128 | 512 (–) | 1024 (–) | 1024 (–) | – | 512 (–) | – | 1024 (–) | 256 (–) | 256 (–) | – | – | 128 (–) | 256 (–) | 256 (–) | 128 (–) | 2 (8) |
MRSA8 | 512 (–) | 1024 (–) | 128 (1024) | 256 (–) | 256 (–) | 512 (–) | 512 (1024) | – | – | 512 (–) | 256 (–) | 512 (–) | – | 512 (–) | 128 (–) | 512 (–) | 256 (–) | 128 (–) | 2 (8) |
MRSA9 | 512 (–) | 1024 (–) | 128 | 512 (–) | 512 (–) | 1024 (–) | 512 (–) | 256 (–) | 1024 (–) | 512 (–) | 256 (–) | 512 (–) | 256 (–) | 512 (–) | 128 (–) | 512 (–) | 128 (–) |
|
2 (16) |
MRSA11 | 1024 (–) | 1024 (–) | 256 | 512 (–) | 512 (–) | 1024 (–) | 512 (–) | 1024 (–) | 1024 (–) | 512 (–) | 256 (–) | 512 (–) | – | – | 128 (–) | 512 (–) | 256 (–) | 128 (–) | 2 (16) |
MRSA12 | 512 (–) | 1024 (–) | 128 | 512 (–) | 256 (–) | 256 (–) | 512 (–) | – | – | 1024 (–) | 256 (–) | 512 (–) | – | 1024 (–) | 128 (–) | 512 (–) | 256 (–) | 128 (–) | 2 (4) |
aBacterial strain (SA:
Four extracts (DES, HEL, UGL, and UGB) and CIP (reference drug) were tested in the absence or presence of CCCP (0.5
MIC of extracts and ciprofloxacin in the absence (−) and presence (+) of carbonyl cyanide
Bacterial strainsa | Samplesb and MIC in | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
DES | HEL | UGB | UGL | CIP | ||||||
− | + | − | + | − | + | − | + | − | + | |
ATCC 25923 | 256 | 32 |
256 | <8 |
– | <8 |
1024 | <8 |
2 | 1 |
MRSA3 | 256 | <8 |
256 | <8 |
512 | <8 |
512 | <8 |
1 | <0.5 |
MRSA4 | 256 | 16 |
128 | 16 |
1024 | 128 |
1024 | 64 |
2 | <0.5 |
MRSA6 | 128 | <8 |
256 | <8 |
1024 | <8 |
512 | <8 |
1 | <0.5 |
MRSA8 | 256 | 128 |
128 | 128 (1) | – | 512 |
512 | 128 |
<0.5 | <0.5 (nd) |
MRSA9 | 128 | <8 |
64 | <8 |
1024 | <8 |
256 | <8 |
<0.5 | <0.5 (nd) |
MRSA11 | 256 | <8 |
128 | <8 |
1024 | <8 |
256 | <8 |
1 | 1(1) |
MRSA12 | 256 | <8 |
128 | <8 |
1024 | <8 |
256 | <8 |
<0.5 | <0.5 (nd) |
SA01 | 128 | <8 |
128 | <8 |
1024 | <8 |
256 | <8 |
<0.5 | <0.5 (nd) |
SA07 | 512 | <8 |
512 | 512 (1) | 512 | 512 (1) | 256 | <8 |
<0.5 | <0.5 (nd) |
SA18 | 1024 | 128 |
256 | 128 |
1024 | 512 |
512 | <8 |
1 | <0.5 |
SA88 | 512 | 512 (1) | – | – | 1024 | 1024 (1) | 1024 | 256 |
1 | <0.5 |
SA114 | 1024 | <8 |
– | – | 1024 | 128 |
512 | <8 |
<0.5 | <0.5 |
SA135 | 512 | 64 |
– | – | – | 128 |
512 | <8 |
1 | <0.5 |
aBacterial strain (SA:
MIC of extracts and ciprofloxacin in the absence (−) and presence (+) of chlorpromazine (CPZ) against selected strains of
Bacterial strainsa | Samplesb and MIC in | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
DES | HEL | UGB | UGL | CIP | ||||||
− | + | − | + | − | + | − | + | − | + | |
ATCC 25923 | 512 | 512 (1) | − | − | 512 | 512 (1) | 128 | 1024 (0.13) | 2 | 2 (1) |
MRSA3 | 256 | 256 (1) | 1024 | 1024 (1) | 512 | 512 (1) | − | − | 4 | 4 (1) |
MRSA4 | 512 | 512 (1) | − | − | 256 | 256 (1) | 1024 | 1024 (1) | 2 | 2 (1) |
MRSA6 | 256 | 256 (1) | 512 | 128 (2) | 512 | 512 (1) | 256 | −(0.25) | 2 | 2 (1) |
MRSA8 | 256 | 256 (1) | 1024 | 1024 (1) | 256 | 256 (1) | − | − | 1 | 2 (0.5) |
MRSA9 | 256 | 256 (1) | 1024 | 1024 (1) | 512 | 512 (1) | 256 | −(0.25) | 1 | 2 (0.5) |
MRSA11 | 512 | 512 (1) | 1024 | 1024 (1) | 512 | 512 (1) | 128 | −(<0.13) | 4 | 4 (1) |
MRSA12 | 512 | 512 (1) | − | − | 512 | 512 (1) | − | − | 2 | 2 (1) |
SA01 | 512 | 512 (1) | 1024 | 1024 (1) | 512 | 512 (1) | 512 | 512 (1) | 1 | 1 (1) |
SA07 | 512 | 512 (1) | 1024 | 1024 (1) | 512 | 512 (1) | 1024 | 1024 (1) | 4 | 4 (1) |
SA18 | 512 | 512 (1) | − | − | 1024 | 1024 (1) | − | − | 1 | 1 (1) |
SA88 | 512 | 512 (1) | − | − | 1024 | 1024 (1) | − | − | 4 | 4 (1) |
SA114 | 1024 | 1024 (1) | − | − | 1024 | 1024 (1) | − | − | 1 | 1 (1) |
SA135 | 512 | 512 (1) | − | − | 1024 | 1024 (1) | − | − | 1 | 1 (1) |
aBacterial strain (SA:
Seven plant extracts, AIB, DES, DEB, DEL, PVL, RHL, and UGB, at their various subinhibitory concentrations (MIC/2, MIC/4, MIC/8, and MIC/16) were first tested in combination with 8 antibiotics: CHL, TET, CIP, AMP, CEF, ERY, STR, and KAN against
Polyphenols and tannins were detected in all extracts. The role of several molecules belonging to polyphenols as antibacterials has been demonstrated [
Resistance of bacteria to antibiotics propels the search of new agents to fight against MDR phenotypes. In the present study, clinical strains of
Bacterial efflux systems are associated with major human health concerns as they are involved in the resistance of pathogenic bacteria such as
The antibiotic resistance-modulating effects of several botanicals and phytochemicals against resistant bacteria have been documented [
In conclusion, the present work provides informative data about the antistaphylococcal potential of 13 Cameroonian food plants. It also indicates that some extracts such as DES, HEL, UGL, and UGB could be used in combination with EPI to combat resistance of
The data used to support the findings of this study are included within the article.
The authors declare that they have no conflicts of interest.
Brice E. N. Wamba, Paul Nayim, Joachim K. Dzotam, and Ornella J. T. Ngalani carried out the study. Armelle T. Mbaveng and Victor Kuete designed the experiments. Armelle T. Mbaveng and Victor Kuete wrote the manuscript. Armelle T. Mbaveng and Victor Kuete supervised the work and provided the bacterial strains. All authors read and approved the final manuscript.
The authors are thankful to the Cameroon National Herbarium for identification of plants and also thank Dr. Jean P. Dzoyem (University of Dschang, Cameroon) for providing the MRSA strains of
Preliminary evaluation of antibiotic resistance modulatory activity of extracts against
Ampicillin
American Type Culture Collection
Carbonyl cyanide
Cefepime
Colony-forming unit
Chloramphenicol
Ciprofloxacin
Chlorpromazine
Dimethylsulfoxide
Efflux pump inhibitors
Erythromycin
Kanamycin
Minimal bactericidal concentration
Multidrug-resistant
Mueller Hinton broth
Minimal inhibitory concentration
Methicillin-resistant
Reference antibiotics
Streptomycin
Tetracycline