Characterization Of Wild-Type Salmonella And Their Susceptibility To “Mist Enterica” An Anti-Typhoid Herbal Preparation

ABSTRACT

The purpose of this study was to investigate the antibiotic resistance and clonal

lineage of Salmonella isolated from patients suspected of suffering from typhoid fever

and the susceptibility of these Salmonella strains to “Mist Enterica”, a herbal

preparation used at the Centre for Scientific Research into Plant Medicine (CSRPM)

out-patients’ department, Mampong-Akwapim, Ghana, to treat typhoid fever. Other

strains of Salmonella isolated from food sources were also included in this study.

A total of 1 IS Salmonella strains were examined for drug/multiple resistance, using

first-line antibiotics used to treat typhoid fever, namely, ampicillin (Am),

chloramphenicol (CmX tetracycline (Te) and trimethoprim-Sulphamethoxazole (Ts).

Streptomycin (St), which is a commonly used antibiotic, was also included. These

strains were isolated from blood, cerebrospinal fluid, stool, urine, food, and other

sources. The minimum inhibitory concentrations (MICs) for the antibiotics were

studied using the 1 IS Salmonella strains. The genetic location of those with resistant

genes was also investigated. Genetic fingerprinting by plasmid profiling,

enterobacterial repetitive intergenic consensus (ERIC) -PCR, and repetitive extragenic

pallindromic (REP)-PCR were performed to determine the diversity among the

isolates. The efficacy of “Mist Enterica” as an anti-typhoid agent and the

contributions made by each of the components of “Mist Enterica” were also

investigated. The MICs for “Mist Enterica”, and three of the component plants,

namely Cnestis ferruginea, Hostundia opposita and Psidium guajava were also

determined.

The number of organisms isolated from blood alone was 82 (71.3%). Eight

serological groups were identified and the most common isolates were groups D

(57.4%) and B (33%), with the least found in groups A, G and 1 Seventy-four percent

of the Salmonella strains (85 out of 115) were resistant to one or more of the five

antibiotics used and of the 85 resistant strains, 37 (43.53%) were resistant to all five

antibiotics, 32 (37.65%) resistant to four, 7 (8.24%) to three, 1 (1.18%) resistant to

two and 8 (9.41%) were resistant to one antibiotic. Thus, 76 Salmonella strains out of

the total 115 (66.09%) were found to possess multi-drug resistance (resistance to three

or more antibiotics). The MIC for ampicillin was found to be equal to or greater than

1280mg/L for 93% of the resistant Salmonella, whilst trimethoprim-

Sulphamethoxazole had MIC of 1280mg/L for 78% and 80mg/L for 22% of the

strains. The MIC for chloramphenicol was equal to or greater than 1280mg/L for

48% of the strains and 20mg/L for 46%. Tetracycline had MIC of320mg/L or lower

for all the 85 resistant Salmonella strains tested. Two groups, Groups B and D,

totaling 104 out of the 115 strains (90%), showed high level of resistance. The

percentage of resistant strains in Group B was 97.3 and that in Group D was 63.6. In

all, majority of the Group B strains (71.05%) were resistant to all five antibiotics

whilst majority of the Group D strains (37.88%) were resistant to four.

Eighly-one out of the 85 resistant strains (95.29%) possessed conjugable plasmids

which conferred multi-drug resistance on 74 of the 81 strains (91.36%). These multidrug

resistant strains belonged to the incompatibility group IncHl. Out of the 85

wild-type resistant Salmonella strains only 15 (17.65%) could transform recipient E.

coli strains, with all these transformants being resistant to ampicillin. Plasmid

profiling discriminated 5 unique groupings, while ERIC-PCR and REP-PCR resulted

in 2 and 3 groupings, respectively.

“Mist Enterica” and decoctions made from Hoslundia opposita, Cnestis ferruginea

and Psidium guajava, three of the components of “Mist Enterica” were found to be

very active against all the standard strains as well as the wild-type Salmonella strains

with zones of inhibition ranging from 9mm to 25mm. These herbal preparations also

inhibited growth of other pathogenic microorganisms such as Staphylococcus aureus,

Staphylococcus saprophyticus, Escherichia coli, Candida albicans and Neisseria

gonorrhoea.

Thus, antibiotic resistance is associated with the Salmonella strains whose genes are

located on conjugative plasmids and appear to be minimally diversified. The results

also indicate that “Mist Enterica” and a combination o f Hoslundia opposita, Cnestis

ferruginea and Psidium guajava (3-in-l) are very efficacious and could be used for

the management of the type of disease caused by the strains of bacteria studied.