Bacteriological analysis and efficacy assessment of liquid herbal mixtures sold in Anyigba, Kogi state, Nigeria

INTRODUCTION

The use of herbal treatment is an old practice usually employed in diseases treatments. It is sometimes referred to as complementary and alternative medicine. It is becoming more main stream as improvements in analysis and quality control along with advances in clinical research show the value of herbal medicine in the treating and preventing diseases. The World Health Organization (WHO) estimates that 4 billion people (about 80% of the world population) use herbal medicine for some aspect of primary health care.^[1] The term “herbal drugs” denotes plants and plant parts that have been converted into phytopharmaceuticals by means of some simple processed state as active ingredients and may contain excipients (foreign substance).^[2] Similarly, the European Medicine Evaluation Agency defines herbal preparations as medicinal products containing exclusive herbal drugs or herbal drug preparations as active substances.^[3]

Herbal medicine has been known to be used to treat many conditions, such as asthma, eczema, irritable bowel syndrome, premenstrual syndrome, rheumatoid arthritis, migraine, menopausal symptoms, chronic fatigue, and cancer among others.^[4] Widespread use of herbal medicine to ensure continued access especially for rural communities, without compromising patient’s safety.^[5] Interest in medical plants as a re-emerging health aid has been fuelled by the rising costs of prescription drugs in the maintenance of personal health and well-being. In Nigeria, even though, there is proliferation of herbal preparations in Nigeria that do not have the required expertise to perform quality control on the preparation that they produce. This brings about the problem of inconsistency on the quality of the herbal preparation in the country.

With the ever increasing use of herbal medicines and the global expansion of the medicines, market safety has become a concern for both health authorities and the public in many countries. This is because many contaminants and residues that may cause harm to the consumers have been reported.^[6] The quality assessment of herbal medications is therefore very important to justify their acceptance in modern system of medicine. It is thus necessary that the microbiological limit test of herbal medicinal preparations be done to ensure that the product is free from risk. Some of the formulations are not subject to aseptic conditions during various stages of preparation, packaging, storage, and transportation, as required by regulatory norms of National Agency for Food and Drug Administration and Control (NAFDAC) which aims at achieving high standards of quality of food and drugs, including herbal preparation in Nigeria. Plants and plant materials also carry huge number of organisms mainly originating from the soil. Aerobic sporulating bacteria frequently predominate in this to which additional contamination and microbial growth occur during harvesting, handling, and production.^[7] It is important that physicians and herbalists have the knowledge about the microbiological safety of these preparations.^[8]

MATERIAL AND METHODS

RESULTS

The result of the microbial load of the different herbal mixtures is shown in [Tables 1 and 2]. The mean heterotrophic count of the different herbal samples ranged from 1.48*10⁵ CFU/ml to 6.8*10⁴CFU/ml.

DISCUSSION

The samples were contaminated to varying degrees with bacteria which are in agreement with previous works on microbial quality by Czech et al.^[12] Two of the four NAFDAC registered herbal preparations were free from microbial contamination. This may be due to natural barriers and antimicrobial substances of different chemical nature as oils, peptides, liquid, and organic extracts contained by certain plants which exert typical inhibitory effects on microbial growth and stability as observed by Idu et al.^[13] According to the WHO standards, values of the microbial limits should not exceed 10⁵ CFU/ml for total aerobic bacteria and 10³ CFU/ml for Enterobacteria, whereas Salmonella and E. coli should totally be absent.^[13] Seventy-five percentages of registered products met these specifications.

All the unregistered samples were not sterile as they had bacterial contamination. This is unlike the registered samples, where two samples were sterile even after repeated tests. This observation is similar to the observation of Onyambu et al.^[14] who observed that unregulated herbal drugs were all contaminated beyond limits.

The characteristics of the isolated organisms as shown in Table 3 in this study are in agreement with the previous works on characterization (Bacillus spp., Staphylococcus spp., Acinetobacter spp., and Enterbacter spp.) as shown in Table 4; all the named pathogens isolated from the indigenous herbal samples in this study have been implicated in the previous studies on gastroenteritis and other transmissible diseases.^[14]

Rajapandiyan et al.^[15] also implemented Enterobacter asburiae as an opportunistic pathogen in extraintestinal infections associated with diarrhea in children and also in nosocomial infections. Therefore, the high recovery rates of these suspected perilous bacteria from indigenous orally consumed herbal medications could be of clinical relevance as shown in Table 5. Acinetobacter baumannii is also an opportunistic pathogen and is becoming increasingly important in nosocomial infections. They are equally known to be multidrug resistant.^[13] Bacillus species are known to cause gastrointestinal infection which is characterized by diarrhea. It has been reported by Rajapandiyan et al.^[15] that Bacillus subtilis is the most predominantly isolated from herbal preparation. This could be due to the fact that they are spore producing organisms.

The high level of microbial contamination observed from the unregistered samples in this study may be attributed to the methods of their preparation as observed by Rocha et al.^[16] The soil, harvesting, drying, improper handling, and storage conditions influence the microbial quality of herbal drugs. The presence of microbial contaminant in the mixtures can reduce or even inactivate the therapeutic activity of the products and has the potential to adversely affect patients.

CONCLUSION

This result has shown that unregistered herbal mixtures marketed in Anyigba are highly contaminated with microorganisms, some of which are pathogenic compared to the regulated ones. Such unregistered herbal mixtures products may facilitate transmission of communicable disease in the population and therefore present a public health problem. Most of the herbal medicines analyzed in this study would be consumed at room temperature and do not get heated to above 60°C before consumption, thereby increasing risk of food-borne infections.