Studies on microbiological concentration of commonly used local complementary foods in three states of North Western Nigeria were carried out. Total aerobic count in complementary foods from Kaduna state was greater than the 104 permissible limits. Unacceptable levels of Salmonella and Shigella were detected in some of the samples. Results also indicated the predominance of Staphylococcus sp. and fungi and molds, which showed that the levels of contamination of some of the samples are very high when compared to International Standards. Attention needs to be paid to the specific behaviours surrounding feeding and any constraints to care as important interventions in order to improve feeding practices in Northern Western Nigeria.
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Complementary feeding period is the time when malnutrition starts in many infants contributing significantly to the high prevalence of malnutrition in children under 5 years of age (Daelmans and Saadeh, 2003) and the deficits acquired at this age are difficult to compensate for later in childhood (Martorell et al., 1994). Illness due to contaminated foods is one of the most widespread health problems in the contemporary world which plays a major role in the occurrence of diarrheal diseases and transmission of this infection occurs by direct contact, which is highly favored by the habits and customs of the people, improper storage and handling of cooked food is equally responsible for food-borne illnesses (Sheth and Dwivedi, 2006). Improving complementary feeding is of highest priority for infant and young children because of its crucial role in preventing mortality and enhancing children development (Lutter and Dewey, 2003).
In Nigeria, 42% of children are stunted, 10% wasted and 25% underweight (NFCNS, 2004). The data available on the regional prevalence of diarrhoea, undernutrition and under 5 mortality in Nigeria showed a strong interaction among these factors, with each of them far more prevalent in the northern than in the southern part of Nigeria (UNICEF, 2001). Exclusive breastfeeding helps to ward off the risk of illness, but the early introduction of other liquids and solids, often prepared in insufficiently hygienic conditions increases the likelihood of infection, resulting in potentially life-threatening conditions such as diarrhoea (UNICEF, 2001). It is hypothesized that the household level nutritional practices could be responsible for the high level of malnutrition in Northern Nigeria. This magnitude of malnutrition deserve urgent attention knowing the consequences of malnutrition as it affects survival and health, education and the economy of the nation (NFCNS, 2004).
The present study was conducted to assess the level of microbial load in commonly used local complementary foods in North Western Nigeria.
MATERIALS AND METHODS
Sample collection: This study was carried out in North Western Nigeria during the year 2005 using the Multiple Indicator Cluster Surveys (MICS) zones and Nigeria Demographic and Health Survey (NDHS) 1990 zones, which was based on agro-ecological zones of the country (UNICEF, 2001). Three States (Kaduna, Kebbi and Niger States) based on Principal Food Crop grown in the Northwest zone were randomly selected for the study.
Representative food samples were collected from mothers with children more than 6 but less than 24 months in a mother/child pair while in the absence of the biological mother, the person considered as the childs caretaker (Father, Aunt, Grandmother) was eligible. Food samples were transported in coolers (4°C) to the laboratory for microbiological analyses.
Microbiological analyses: All microbiological analyses were carried out based on procedures recommended in the International Commission on Microbiological Specification for Foods (ICMSF, 1996). An appropriate serial dilution of all the commonly used local complementary food samples was carried out and 0.1 mL of the selected dilution was spread on triplicate plates using sterile glass spreader. This technique was used for the enumeration of total aerobic count, E. coli counts, Staphylococcal counts, Salmonella and Shigella counts and fungi and molds counts on Nutrient Agar, Eosin Methylene Agar, Salmonella and Shigella Agar and Sabourand Glucose Agar. Media used were prepared according to the manufacturers instructions.
Analysis of data: Analysis of data was done using the Microsoft Excel data analysis package for windows. Frequencies for various responses for the commonly used local complementary foods were generated. Results for the microbiological analyses were expressed as mean±standard deviation. The difference between groups of each parameter was determined using the t-test and statistical significance were claimed at p<0.05 (95% confidence limit).
Local complementary foods in Kaduna state: Total aerobic count of organisms in KDPS (285.33±12.86x105cfu g-1) was significantly (p<0.05) higher while KDGP had the lowest count (2.30±1.15x105 cfu g-1). KDMP recorded highest (p<0.05) E. coli count of 129.33±20.13x104 cfu g-1 while lowest count of 2.00±0.41x104 cfu g-1 was in KDLP. Staphylococcal count was significantly (p<0.05) highest in KDFN (77.50±0.71x103 cfu g-1) and lowest in KDPS (2.00±1.00x103 cfu g-1). KDFN recorded highest (p<0.05) Salmonella and Shigella count of 194.50±22.73x103 cfu g-1 followed by KDMP which had 85.00±4.50x103 cfu g-1 and KDPS with 66.67±6.01x103 cfu g-1. The fungi and mould count results showed that KDMP had the highest count of 386.67±106.16x104 cfu g-1 followed by KDPS and KDFN which gave counts of 173.33±4.16x104 cfu g-1 and 100.33±12.01x104 cfu g-1, respectively. The lowest counts were recorded in KDGP (9.33±2.52x104 cfu g-1) and KDLP (9.50±0.19x104 cfu g-1) (Table 1).
Local complementary foods in kebbi state: The highest total aerobic count of organism was in KBFN (24.33±6.11x105 cfu g-1) which was significantly different from KBDM (12.33±0.58x105 cfu g-1). E. coli count were also recorded in KBFN (32.50±3.54x104 cfu g-1) and KBDM (3.00±1.41x104 cfu g-1) which are significantly different (p<0.05). Significantly (p<0.05) higher Staphylococcal counts was recorded in KBDM (17.67±4.04x103 cfu g-1) while KBGP had the lowest counts of 2.00±0.00x103 cfu g-1. For Salmonella and Shigella count KBGP recorded the highest (480.10±40.50x103 cfu g-1) followed by KBFN and KBMP which both recorded the lowest counts (Table 2). Fungi and Mold counts of organism in local complementary foods in Kebbi state was significantly (p<0.05) higher in KBMP with 239.33±52.54x104 cfu g-1 compared to the other samples from the state.
Local complementary foods in Niger state: Results in Table 3 showed the mean count of organisms in commonly used complementary foods in Niger state. Total aerobic count of organism in NGTW (27.00±9.54x105 cfu g-1) was higher significantly (p<0.05) compared to NGFN (1.50±0.71x105 cfu g-1) and NGMG (10.67±4.04x105 cfu g-1). E. coli counts in NGFN (90.33±22.68x104 cfu g-1) was also significantly (p<0.05) higher than NGRG (2.33±0.31x104 cfu g-1). Staphylococcal count showed that NGRG with 2.67±0.00x103 cfu g-1 counts was significantly (p<0.05) lower than that obtained in NGFN and NGTW. The highest count of Salmonella and Shigella was in NGFN with 63.67±11.06x103 cfu g-1 compared to NGTW which had 3.33±1.15x103 cfu g-1. Significantly (p<0.05) higher fungi and mould count were in NGFN and NGTW which had 47.67±4.04x104 cfu g-1 and 43.50±2.12x104 cfu g-1, respectively than NGRG with 13.00±8.66x104 cfu g-1. NGMG did not showed any growth for E. coli, Staphylococcal, Salmonella and Shigella and Fungi and Mold (Table 3).
Most probable number of organism (MPN): For those used in Kaduna state, KDFN had highest number of organism (430 MPN g-1) while KDLP recorded the lowest (7 MPN g-1). KBDM commonly used in Kebbi state had >1600 MPN g-1 of sample and the lowest number was in KBLP with 25 MPN g-1. Niger state samples showed that NGTW had the highest (24 MPN g-1) followed by NGRG (17 MPN g-1) and NGFN (15 MPN g-1) while NGMG had <2 MPN g-1 (Table 4).
|Mean count of organisms in commonly used local complementary foods in Kaduna state (cfu g-1)
|Values are means±SD of triplicate determinations, Values in the same column with different superscripts are significant (p<0.05). NG = No Growth, KDFN = Fura nono, KDGP = Guinea corn pap, KDLP = Millet pap, KDMP = Maize pap and KDPS = Maize Porriage (pate)
|Mean count of organisms in commonly used local complementary foods in Kebbi state (cfu g-1)
|Values are means±SD of triplicate determinations, TNTC = Too Numerous To Count, Values in the same column with different superscripts are significant (p<0.05), NG = No growth, KBPS = Tuwo (Dami), KBFN = Fura nono, KBGP = Guinea corn pap, KBLP = Millet pap and KBMP = Maize pap
|Mean count of organisms in commonly used local complementary foods in Niger state (cfu g-1)
|Values are means±SD of triplicate determinations Values in the same column with different superscripts are significant (p<0.05), NGFN = Fura nono, NGMG = Guinea corn/millet pap, NGRG = Rice/groundnut pap, NGTW = Tuwo and NG = No Growth
|Most probable number of organism (MPN) in commonly Used local complementary foods
|KDFN = Fura nono, KDGP = Guinea corn pap, KDLP = Millet pap, KDMP = Maize pap, KDPS = Maize Porriage (pate), KBPS = Tuwo (Dami), KBFN = Fura nono, KBGP = Guinea corn pap, KBLP = Millet pap, KBMP = Maize pap, NGFN = Fura nono, NGMG = Guinea corn/millet pap, NGRG = Rice/groundnut pap and NGTW = Tuwo
Studies have shown that poor drinking water facilities, inadequate sanitary facilities and poor hygiene, particularly during food preparation are the main causes of many infections among the young children (WHO, 1993). And the best way to ensure that food and water are free from contamination is to heat them to a sufficiently high temperature (>70°C) immediately prior to serving. Microbiological analyses are useful ways to assess the safety and quality of food. Aerobic colony count is a count of viable bacteria and it indicates the level of microorganisms in a product. Total aerobic count in complementary foods from Kaduna state was greater than the 104 permissible limits (ICMSF, 1996) except for KDLP that had satisfactory level (Table 1). Unsatisfactory levels of aerobic colony counts were detected in KBDM and KBFN (Table 2) while other samples from Kebbi state recorded satisfactory levels. Levels of aerobic colony counts in complementary foods obtained in Niger state (Table 3) were found to be unsatisfactory except for NGRG which was satisfactory when compared to microbiological quality standards (ICMSF, 1996).
Indicator organism refers to the selected surrogate markers and the main objective of using bacteria as indicators is to reflect the hygienic quality of food. E. coli is commonly used as surrogate indicator and its presence in food generally indicates direct or indirect fecal contamination. Substantial number of E. coli in food suggests a general lack of cleanliness in handling and improper storage (ICMSF, 1996). KDGP recorded satisfactory levels of E. coli whereas Staphylococcus counts in all food samples from Kaduna state were unsatisfactory (Table 1). Acceptable level of indicator organism E. coli and Staphylococcus, an Enterobacteriaceae counts were detected in NGMG and NGRG (Table 3) while all other samples had unsatisfactory levels of both microorganisms. Unsatisfactory levels of E. coli counts also were detected in KBDM and KBFN while other samples from Kebbi state recorded satisfactory levels (Table 2). KBFN and KBMP had satisfactory levels of Staphylococccus counts.
The presence of E. coli in ready-to-eat foods is undesirable because it indicates poor hygienic conditions which have lead to contamination or inadequate heat treatment (ICMSF, 1996). Ideally E. coli should not be detected and as such a level of <3 g-1 (the limit of the Most Probable Number test) has been given as the satisfactory criteria for this organism. Levels exceeding 100 g-1 are unacceptable and indicate a level of contamination which may have introduced pathogens or that pathogens, if present in the food prior to processing, may have survived. The family Enterobacteriaceae includes many bacteria that are found in the human or animal intestinal tract, including human pathogens such as Salmonella and Shigella enterobacteriaceae are useful indicators of hygiene and of post-processing contamination of heat processed foods (ICMSF, 1996). Their presence in high numbers (>104 per gram) in ready-to-eat foods indicates that an unacceptable level of contamination has occurred or there has been under processing like inadequate cooking.
Specific pathogens are bacteria that may cause food poisoning and mechanisms involved may be toxins produced in food or intestinal infection. The symptoms of food poisoning vary from nausea and vomiting caused by Staphylococcus aureus, through diarrhoea and dehydration by Salmonella sp. and Campylobacter sp. to paralysis and death in the rare cases of botulism. The infectious doses vary from less than 10 to more than 106 organisms (ICMSF 1996). Unacceptable levels of Salmonella and Shigella were detected in NGFN and NGTW (Table 3) however, satisfactory levels of Salmonella, were recorded in KDGP and KDLP while the rest had unacceptable levels (Table 1). Ready-to-eat foods should be free of Salmonella as consumption of food containing this pathogen may result in food borne illness. The presence of this organism indicates poor food preparation and handling practices such as inadequate cooking or cross contamination (ICMSF, 1996).
The presence of fungi in a food product is undesirable (Adegoke, 2004) and have been implicated in food poisoning illness and also known as spoilage microorganisms (Yusuf et al., 1992). High levels of fungi and molds were recorded in all the commonly used local complementary foods from all the states studied (Table 1-3) except for NGMG which had satisfactory level.
Results indicates the predominance of Staphylococcus sp. and fungi and molds in the complementary foods commonly used in North Western Nigeria, which indicates that the levels of contamination of foods were very high when compared to International Standards (ICMSF, 1996). There is the need for caregivers in the region to adopt strict hygienic practices (Badau et al., 2005). The presence of Staphylococcus sp. could be as a result of processors handling (Babajide et al., 2006) while presence of coliform is an indication of fecal contamination (Tahir and Oyawole, 1993) and they also reported that microbial quality of tap water supplied to some communities in Nigeria is poor with coliform counts exceeding recommended level. A study of complementary food preparation and handling in Eastern Nigeria also confirmed the presence of enteric pathogens and that the exotoxin of Staphylococcus sp. is associated with food poisoning and spores of pathogens with handlers (Ehiri et al., 2001). High levels of pathogens such as Staphylococcus, Salmonella and Shigella and E. coli are sometimes found in traditional foods after processing under unhygienic conditions (Mbugua and Njenga, 1991; Svanberg, 1991). The coliforms may include strains of E. coli which is heat stable form, as the virulence factor of enterotogenic E. coli strains which can withstand 100°C for 15 min (Adegoke, 2004).
Attention needs to be paid to the specific behaviours surrounding feeding like personal and domestic hygiene and any constraints to care and not just to the nutritional aspects of complementary foods as important interventions in order to improve feeding practices in Northern Western Nigeria. The food preparation habits of caregivers should be studied using the Hazard Analysis Critical Control Point system as a methodology.
This study was funded by the University Board of Research, Ahmadu Bello University, Zaria-Nigeria.
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