objects , features , and aspects of the present invention are disclosed in or are obvious from the following description . it is to be understood by one of ordinary skilled in the art that the present discussion is a description of exemplary embodiments only , and is not intended as limiting the broader aspects of the present invention , which broader aspects are embodied in the exemplary constructions . according to this invention , it is surprisingly found that extracts of the woody mushroom ganoderma lucidum ( also known as “ lingzhi ” and “ reishi ”) are capable of lowering the minimal inhibitory concentration ( mic ) of antibiotics . mic is defined as the lowest concentration that results in inhibition of visible growth of the organism . the g . lucidum extracts may include , but not limited to hot water extract ; water - ethanol ( polysaccharide - rich ) extracts ; methanol - chloroform ( triterpene - rich ) extracts of the fruiting body and / or spores of g . lucidum . it is also found that the amount of the extracts added to the antibiotics can be very small to be effective , as small as 1 % w / v . obviously amount of the extracts cannot be 100 %, otherwise no antibiotics are present in the formulation . however , there is no report of lingzhi toxicity in the literature . therefore , it appears to be safe even if high doses of the lingzhi extracts are used , for example 30 g per day . many antibiotics can be used with the lingzhi extracts , including the beta lactam group and glycopeptide group of antibiotics . examples of the beta lactam group of antibiotics include penicillin , methicillin , ampicillin , piperacillin , cephalosporins , carbapenems . representatives of the glycopeptide group of antibiotics may include vancomycin and teicoplanin . various lingzhi extracts may be used , including hot water extract , alcohol extract ( polysaccharide rich extract ), or even commercially available extracts may be used . details will be described in the following section . the fruit bodies of the dried mushroom were washed under running tap water followed by distilled water . the fruit bodies were then put on the bench at room temperature (˜ 20 ° c .) until dry ( around 2 days ). after drying , the fruit bodies were cut into small pieces and extracted . dried fruit bodies were extracted with distilled water at 100 ° c . ( in water bath ) for 3 hours , and mixed every 15 min . after extraction , the samples were filtered ( whatman filter paper # 2 ) and the filtrate was freeze - dried or lyophilized ( labconco corp ., kansas city , mo ., usa ). this extract was called mushroom hot water ( mhw ). fruit bodies were extracted with distilled water at 100 ° c . for 3 hours ( as for hot water extract above ). after extraction , the samples were filtered and the filtrate was concentrated by lyophilization . absolute ethanol was then added to the concentrate ( 80 % saturation ) and the mixture was allowed to stand overnight at 4 ° c . the precipitate was collected by centrifugation ( sorvall rc - 2b , kendro laboratory products , ashevillence , n . c ., usa ). the precipitant was re - dissolved in distilled water and dialyzed at 4 ° c . overnight against distilled water ( 10k cut - off membrane ). the dialyzed material was then lyophilized . commercially available capsules containing an extract of g . lucidum were also tested . for the samples used in this study , a certificate of analysis was provided . these commercial extracts are sold as ‘ over the counter ’ dietary supplements in pharmacies and drug stores in hong kong as of now ( 2005 ). water preparations of fruit bodies or commercial extracts were prepared . for preparations of water extracts , 1 % w / v commercial extract ( chw ), mushroom &# 39 ; s fruit bodies hot - water extract ( mhw ) and mushroom &# 39 ; s fruit bodies polysaccharide - rich extract ( mpr ) were weighed and dissolved in boiling water . the mixtures were then vortexed and then roller mixed for the next 30 minutes . the suspensions were filtered and the filtrates collected for further investigation . antimicrobial susceptibility testing was performed by broth assay followed standard laboratory procedures ( the national committee for clinical laboratory standards ( nccls ) protocol 2000 ). the mic in this assay was defined as the lowest concentration of the antibiotic under test that inhibited the visible growth of the microorganism under study . there were eight strains of staphylococcus aureus tested . all were from clinical isolates as they represent strains actually present in the community and so of clinical relevance . three strains were sensitive to methicillin ( mssa ), and five strains were resistant to methicillin ( mrsa ). the mic for each of the eight strains was determined for penicillin g and for vancomycin using dilutions made from the stock preparations purchased ( both from sigma ). the effect of g . lucidum extracts ( mhw , mpr and chw ) on the mics was investigated by adding each type of extract ( individually and at 1 % w / v final concentration in the test mixture in each case ) alone and in combination with each dilution of each antibiotic tested and against all 5 strains of staphylococcus aureus . the details are illustrated in the following paragraphs . the antimicrobial susceptibility test was performed in a 96 - well microtitre plate and following standard national committee for clinical laboratory standards ( nccls ) protocol ( nccls , 2000 ). in this assay , two - fold dilution of the examined agent is performed sequentially along the rows . minimal inhibitory concentration ( mic ) was determined by the microdilution method in mueller - hinton broth ( oxoid , hampshire , uk ), according to the standards of the nccls ( 2000 ). the mic was defined as the lowest concentration that results in inhibition of visible growth of the organism . the mic for each of the strains was determined for penicillin g ( sigma ) and vancomycin ( sigma ) by broth microdilution , using dilutions from a stock concentration of each antibiotic of 4096 μg / ml ( nccls , 2000 ). the different extracts were : mushroom &# 39 ; s fruit body hot water extract ( mhw ), polysaccharide - rich extract ( mpr ), and a commercial extract ( chw )- preparations of the extracts , source of the fruit bodies and commercial extracts are described in the section following the results . the g . lucidum preparations were adjusted to ph 7 . the final concentration of the g . lucidum extracts in the microplates was 1 % w / v . the antibiotics and g . lucidum were both filtered before use . each bacterial strain was plated overnight on mueller - hinton agar and then transferred to a broth 3 hours before the assay was performed . 5 μl of bacterial suspension adjusted to the turbidity of the 0 . 5 mcfarland standard was added to each well , to yield a final inoculum of ˜ 4 × 10 4 cfu / well . plates were covered and incubated at 37 ° c . microplates were examined 18 hours later and determined for mic . the mic was the lowest concentration of antimicrobial agent that yielded no growth by visual reading after incubation . samples of each strain of bacteria were incubated with an antibiotic alone , g . lucidum alone or a combination of the two agents . the first experiments were to find the mic concentrations of the antibiotics for the different strains examined . the next set of experiments tested the effect of each of the three types of g . lucidum alone and in combination with each of the antibiotics . the fractional inhibitory concentration ( fic ) was also calculated . the fic is defined below and is an indication of whether a combined treatment is synergistic , additive , has no effect or is antagonistic . fic ( a ) = mic ⁢ ⁢ ( drug ⁢ ⁢ a ⁢ ⁢ in ⁢ ⁢ the ⁢ ⁢ presence ⁢ ⁢ of ⁢ ⁢ b ) min ⁢ ⁢ ( a ⁢ ⁢ alone ) fic less than or equal to 0 . 5 indicates a synergistic effect ; fic greater than or equal to 2 . 0 indicates an antagonistic effect . none of the three linghzi extracts showed inhibition of the different strains at concentrations up to 1 % ( final concentration ). mic concentrations of the different strains to penicillin ranged from 8 to 1024 μg / ml and , to vancomycin , between 0 . 5 to 1 μg / ml ( table 1 ). the fractional inhibitory concentration ( fic ) results are summarised in table 2 . as can be seen , g . lucidum showed synergistic or additive effects with both penicillin and vancomycin against the tested strains of mssa and mrsa . the results of the experiments show that g . lucidum or lingzhi extracts are able to lower the minimal inhibitory concentration of different antibiotics . therefore , a lower amount of dosage rate of antibiotics may be used to treat infections in conjunction with lingzhi extracts . none of the g . lucidum extracts tested showed a direct effect ( at 1 % w / v ) in regard to inhibition of growth of any of the strain tested . there was a significant mic lowering effect seen with all strains for penicillin in the presence of g . lucidum extract tested . in some cases the mic was reduced back into the therapeutic range for penicillin ( known in the art as 4 ug / ml ). in some cases the susceptibility of the organism to the antibiotic was increased up to 16 fold or more . for vancomycin , evidence of increased efficacy can also be observed in the presence of each g . lucidum extract . the fic results as presented in table 2 show evidence of additive or synergistic effects between g . lucidum and penicillin , and between g . lucidum and vancomycin against the tested strain of mssa and mrsa . results presented show that g . lucidum extracts are able to lower the minimal inhibitory concentration ( mic ) of different antibiotics against clinically relevant strains of pathogenic bacterial including , importantly , methicillin resistant staphylococcus aureus ( mrsa ). this means that the efficacy of these antibiotics is improved in the presence of g . lucidum extracts . in some cases the mic was reduced back to the achievable therapeutic range . results indicate that well tolerated , established and inexpensive antibiotics ( for example penicillin ) that are often no longer used because of antibiotic resistance to their action can be restored to have therapeutic efficacy when used in a combination with an extract of g . lucidum . results also indicates that , in combination with g . lucidum , the same therapeutic effect may be achieved with a lower dose . in another words , same dose of an antibiotic , for example vancomycin , may achieve a significantly greater therapeutic effect . while the preferred embodiment of the present invention has been described in detail by the examples , it is apparent that modifications and adaptations of the present invention will occur to those skilled in the art . furthermore , the embodiments of the present invention shall not be interpreted to be restricted by the examples or figures only . it is to be expressly understood , however , that such modifications and adaptations are within the scope of the present invention , as set forth in the following claims . for instance , features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment . thus , it is intended that the present invention cover such modifications and variations as come within the scope of the claims and their equivalents .
it is desirable to use lower doses of antibiotics in treating bacterial infections , as antibiotics are expensive and may come with undesirable side effects including kidney and / or liver damage . moreover , using a high dose of antibiotics may lead to development of resistance in bacteria to the antibiotics themselves . more importantly , increasing the dosage may not be able to increase the amount of antibiotics entering the body . therefore , it may be desirable to devise methods to lower the minimal inhibitory concentration of antibiotics . this invention provides a method to reduce the minimal inhibitory concentration of antibiotics by adding ganoderma lucidum , or commonly know as lingzhi , extracts , and therefore , lower does of antibiotics may be required .