ABSTRACT
This study was carried to determine the occurrence of Staphylococcus aureus and Escherichia coli in yoghurt and ice cream and also to determine their susceptibility to antibiotics and the total viable count of the bacteria. Fifty (50) samples of yoghurt and fifty (50) samples of ice cream was analyzed for total viable counts which ranged from 1.4 x106 CFU/ml - 2.0 x 107 CFU/ml for Staphylococcus aureus and the viable count of Escherichia coli was ranged from 1.4 x102 CFU/ml - 2.0 x 102 CFU/ml. Staphylococcus aureus and Escherichia coli was isolated in a good number of the samples. Other organisms isolated are; Streptococcus spp, Staphylococcus epidermidis and Lactobacillus species. Their susceptibility of antimicrobials was carried out to test for the sensitive and resistance drugs of the isolates. Some were resistance while some were sensitive to the antibiotics used. Escherichia coli isolates were resistant to Streptomycin, Tetracyclin and Sulfomethaxade and were sensitive to Ampicillin, Chlorophenicol, Gentamycin, Kanamycin and Amoxicillin. While Staphylococcus aureus isolates were resistant to Cloxacillin, Tetracyclin and Chloramphenicol and sensitive to other antibiotics. These isolates of pathogens from yoghurts and ice cream samples analyzed, poses a health risk to the consumers and these results indicates unhygienic conditions of food handlers and inadequate control during processing. Personal hygiene and processing industries should be adhered in order to avoid outbreak of yoghurt or ice cream drinks that have been contaminated.
TABLE OF
CONTENTS
Title page
Certification i
Dedication ii
Acknowledgements iii
Table of contents iv
List of tables vii
Abstract viiii
CHAPTER ONE
INTRODUCTION 1
1.1 Background of the Study 1
1.2 Yoghurt and Ice cream 3
1.2.1 Yoghurt 3
1.2.2 Ice Cream 4
1.3 Nutritional Value of Yoghurt 5
1.4 Essential Nutrients of yoghurts and ice
cream 6
1.5 Yoghurt and Health 8
1.6 Milk 9
1.7 Fermentation 11
1.8
Drug Resistance 12
CHAPTER TWO
LITERATURE REVIEW 15
2.1 Qualities of milk used in yoghurt and ice
cream preparation 15
2.2 Pathogenic of Microorganisms in the Milk 15
2.3 Significance of microorganisms in milk 17
2.4 Spoilage of microorganisms in the milk 17
2.5 Characteristics
of Staphylococcus aureus and E.coli 18
2.6 Microorganisms in Milk 20
CHAPTER THREE
METHODOLOGY 24
3.1 Materials
and methods 24
3.2
Preparation of the media 24
3.2.1
Preparation of the Samples 24
3.2.2
Isolation and Enumeration of S.aureus
and E.coli and Total Viable Counts 25
3.2.3
Characteristics and Morphological
Identification 25
3.2.4
Gram Stain Test 25
3.3 Coagulase
Test 26
3.3.1 Catalase
Test 26
3.3.2 Oxidase
Test 27
3.3.3
Antimicrobial Susceptibility Test 27
CHAPTER
FOUR
Result
28
CHAPTER FIVE
5.1
Discussion 34
5.2
Recommendation 36
5.4
Conclusion 37
References
LIST OF TABLES
Table 1: Total viable count of the bacteria in
(CFU/ml) 29
Table
2: Total mean count of Staphylococcus
aureus and Escherichia coli 30
Table 3: Biochemical and Morphological characteristics
of the isolates 31
Table 4: Antibiotic
sensitivity of Staphylococcus aureus isolates 32
Table 5: Antibiotic sensitivity of Escherichia coli isolates 33
CHAPTER ONE
INTRODUCTION
1.1
Background of the Study
Staphylococcus aureus is a gram-positive, spherical cocccus having a diameter of 1µm – 1.3µm. in
microscopic examination, the organisms appears in clusters, like bunches of
grapes. Some strains produce toxins while growing in food. These toxins can
cause gastrointestinal disease generally referred to as Staphylococcal food posing. The exterotoxin produced by S.aureus
is a heat stable protein that resists heating at 1000c for 30 –
70mins. S.aureus is a thus, also responsible for food borne infections
(Garcia-Alvarex et al., 2011). It is
usually a golden or yellow when grown on solid media and exist in air, dust,
sewage, water milk and food or on food equipment, environment surfaces human
and animals.
Various
diseases conditions caused by this organisms are; wound infections, septicaemia
and toxic shock syndrome. Besides skin, pustules, impetigo, osteomyelitis,
renal abscess, pneumonia, endocarditis, meningitis, gastroenteritis and
sometimes serious conditions in patient with undergoing haemodialysis, diabetic
mellitus etc. such as may also be caused by
S.aureus (Lewis and Jorgenson, 2007). Several methods such as grams staining,
cell morphology, production of catalase and coagulase enzymes, pigment
production, susceptibility to lysostaphin and lysozyme and anaerobic production
of acid from glucose are used for identification of S.aureus
(Paul et al., 2009). Besides, several
commercially available systems that allows strains to be biochemically
characterized, have also been developed. Other species of Staphylococcus genus are
also implicated in similar disease condition. For example S.epidermidis is involved
in bacteria endocarditis prosthetic heart valve endocarditis, bacteremia
surgical wound infections, intravascular catheter infections, postoperative
endophthalmiis, conjunctivitis and keratitis. Other species of Staphyloccous such as S.saprophyticus, S.epidermidis and S.hyicus
may sometimes be involved but these can be distinguished from S.aureus. The coagulase negative Staphylococci (CoNS) species have been
implicated at low incidence in a variety of infections. For example, S.saprophyticus is often regarded as a
more important opportunistic pathogen than S.epidermidis
in human urinary tract infections (UTIs), especially in young sexually active
females.
Other Staphylococcus species such as S.haemolyticus,
S.horminis and S.lugdunensis are usually found as contaminants of blood cultures
but these organisms could be also associated with a variety of infection
(Martineau et al., 2011).
S.aureus, these
most pathogenic species of Staphylococci
is widely distributed and found almost everywhere, particularly on the skin of
humans and animals (Mathanaraj et al.,
2009). About 60% of human population is estimated to be colonized by S.aureus and 20% of humans are persistent
carriers. The nose is most favourable site (Zorgani et al., 2009) but the organism can also survive on the skin and on
the environment for a long time. Colonization of Methicillin resistant S.aureus (MRSA) also occurs at sites
other than the nose eg. Pharynx, axila, rectum, perineum (Eveillard et al., 2014) which might play an
important role in the transmission of infection. Until recently, Methicillin
resistant S.aureus (MRSA) has been
primarily considered as nosocomial infection, acquired in hospital settings
mainly affecting healthcare workers (Zorgani et al., 2009). The
organisms has also been isolated from ice cream (Ojokoh, 2006) rice, fruits,
meat and meat product (Sokari, 1990).
Escherichia
coli
E.coli are
common gram negative bacteria that form a normal parts of the gut flora of
humans and animals. Most of the microorganisms are harmless and are an
essential parts of the digestive system. However, among large number of genetic
types of Escherichia coli, some cause human diarrhoea, E.coli 0157 is spread to human by
swallowing materials that are contaminated with E.coli 0157 from faecal sources. People can become infected with E.coli 0157 through consuming
contaminated food or drinks, through direct contact with contaminated animals
or by contact with environment, contaminated with animal faeces, direct spread
from person to person also occurs. CDC (2010). They are usually to be
opportunistic pathogens which constitute a large portion of the normal
intestinal flora of humans. The bacteria can contaminate, calorize and
subsequently cause infection of extra intestinal sites and are caused of any
infection that affect the blood stream of septicemia peritonitis, abscesses,
meningitis and urinary tract infections (UTI) in humans. E.coli is an incredibly diverse bacteria species with the ability
to colonize and persist in numerous niches both in the environment and within
animal hosts (Okonko et al., 2011).
1.2 YOGHURT
AND ICE CREAM
1.2.1 Yoghurt
Yoghurt
is one of the most unique and universal dairy products because of its
beneficial and therapeutic properties. It is considered a main source of high quality
fats, proteins, calcium, phosphorus and potassium along with significant
quantities of several vitamins. The lactose content is easily absorbed even by
lactose content is easily absorbed even by lactose Maldigestors, as it is converted
to lactic acid by lactic acid bacteria (Yoghurt starter culture). Yoghurt is
valuable adjunct to any healthy diet (Ghadge et al., 2009). Yoghurt
has a therapeutic value as it proved to
prevent the intestinal putrefaction resulting from anaerobic decomposition,
prevents coronary heart disease, reduce the risk of colon cancer, exerts a
hypocholesterolemic effect and produce antibiotics as acidophilin, lactocidin,
nicin and lactoline that inhibit the growth of many pathogen (Elson and Haas,
2008). In spite of advanced dairy products as yoghurt may serve as a vehicle of
food borne pathogens various (Erazier and Westhoff, 2010). Staphylococcus aureus is
one of the most important pathogen in milk or its products (Leloir et al.,
2009). The presence of Staphylococcus
aureus in yoghurt could also be
because of the unhygienic processing, handling and packaging (Prescott et al.,
2012). Also lactating animals and human handlers are main sources for this
bacterium and frequently implicated in the transmission of this pathogen
(Char et al., 2011). Staphylococcus aureus food poisoning (SFP) is one of such organisms which can
transmitted to human through contaminated and untreated milk and milk products
(Seifu, et al., 2012). Due to continuous demands for yoghurts and the increase
of consumers awareness of the product safety as well as to ensure a safe
supply, it is extremely necessary not only to increase the production of this
important products by also to ensure the bacteriological safety of the product
to safeguard consumers against health hazard. Therefore, they represent study
was planned out to cover the isolation of
S.aureus by detection of enteriotoxins
produced by the isolated strains and detection of virulent genes responsible
for toxins production by using PCR in balady and automatically packaged plain
yoghurt (PHA., 2009).
1.2.2 Ice
Cream
Ice
cream is the major dairy products which is one of the favorite food items in
large segment of population. It is a nutritionally enriched frozen dairy products
consumed by all age groups particularly children during summer (Shariff et al., 2009). Ice cream is a products
of mixture consisting milk, sweetening and stabilizing agents together with
flavouring and coloring matter. (Graff-Johnson, 2013). Different ingredients
like milk, cream, evaporated or condensed milk, dried milk, coloring materials,
flavor, fruits, nets, sweetening agents, egg products and stabilizers are used
in ice cream preparation. Also, there are many parameters which should be controlled
accurately during processing to obtain a high quality ice cream with the
required taste, flavor, viscosity, consistency and appearance (Yamaru et al.,
2014). Due to its composition it can
harbor many potent pathogens. Handling and storage conditions are some of these
variables because they affect the physical chemical and microbial quality of
product (Marshall and Arbuckle, 2009, Warke et
al., 2010, Champagne et al.,
2011, Daniel et al., 2012). Most ice creams become contaminated with microbes
during production transit and preservation. The possibility of curing food
borne diseases by infant, children, elderly people and immune suppressed
patients is more due to contaminated ice creams. During last few decades, it
has been seen that consumption of contaminated ice cream are responsible for
disease outbreaks in many countries from Asia, Europe and North America (Chug,
2008; Djuretic et al., 2009; Digrak
and Ozcelik, 2007). Since the consumption of ice cream is higher among children
of vulnerable age groups, there is a need to maintain a high microbiological
safety standard (Champagne et al., 2012). It is a known facts that
relatively low storage temperature and pasteurization steps during processing
of ice creams are considered to eliminate most of the pathogenic microorganism.
However, the addition of contaminated ingredients, improper handling and due to
improper storage temperatures are the factors that contribute to the potentials
hazards of the finished products especially during processing after pasteurization
process (Vernma et al., 2008).
1.3 NUTRITIONAL
VALUE OF YOGHURT
The
nutritionally value of yoghurt is considered as one of the most beneficial and
therapeutic properties; it is the main source of high quality of fats,
proteins, calcium, phosphorus and potassium along with significant quantities
of several vitamins. The lactose content is easily absorbed even by lactose
Maldigestors as it is converted to lactic acid by lactic acid bacteria (Yoghurt
starter culture). Yoghurt is valuable adjunct to any healthy diet (Ghadge et al.,
2011). Yoghurt has it therapeutic value as it proved to prevent the intestinal
putrefaction resulting from anaerobic decomposition prevent the
gastrointestinal disorders, prevents coronary heart disease, reduce the risk of
colon cancer, exert a hypocholesterolemic effects and produce antibiotics as
acidophilin, lactocidin, nicin and lactodine that inhibit the growth of many
pathogens (Elsona and Haas, 2012).
Cow’s
milk is commonly available worldwide and as such is the common used to make
yoghurt. Milk from water buffalo, goats, ewes, mares, camels, and yaks is also
used to produce yoghurt where available locally. Milk used may be homogenized
or not. Yogurt is produced using a culture of lactobacillus delbreuckii
subspecies. Bulgaricus and Streptococcus thermophiles bacteria. In addition, other lactobacilli and bifidobacteria
are also sometimes added during or after culturing yoghurt. Yoghurt is a component
of the DASH (Dietar approaches to stop hypertension) diet designed to reduce
the risk of high blood pressure. This diet, which includes three servings a day
of low fat and fat free milk, yoghurt and cheese and 8 to 10 servings of fruits
and vegetables has also shown to reduce the risk of heart disease and stroke.
(Zecconi and Piccinini, 2009).
1.4 ESSENTIAL
NUTRIENTS OF YOGURTS AND ICE CREAM
Ensuring
the safety and quality of food products is essential to public health, making
it necessary that these issues constitute a reference for the food industry,
particularly for dairy products. A great variety of microorganism colonizes and
grows in common food products. Many products provides an environment suitable
for the growth of microorganism, reducing the product quality and the
availability of this products to the consumer (Diego G.T et al., 2009). The deterioration of food products is defined as any
alteration in the appearance, odor or taste of a food products which makes it
unacceptable to the consumer foods which have deteriorated do not necessarily
pose a risk to the consumer; however, in some cases, pathogenic organism may be
responsible for the deterioration.
Food
safety currently presents a challenge and needs to be considered throughout the
food chain. The microbiological examination of a food products can be carried out,
among other reasons to verity its microbiological quality or to ascertain that
it satisfies certain microbiological criteria. Indicator microorganism have
been researched in order to verify the hygiene-sanitary quality of food
products and the result of microbiological analysis indicate the quality of the
raw materials employed, the cleanliness of the food preparation conditions and
the efficiency of the preservation methods.
Several
microorganism can cause problem when present in food products, both financially
and in terms of health. These include the group of microorganism called coliforms (total on thermotolerant), Staphylococcus aureus, filamentous fungi, yeasts and Salmonella spp. A characteristic of coliform is that they can ferment
lactose with the subsequent formation of gas. The main microorganism which
represent this group is Escherichia coli, which lives in the intestine of
warm-blooded animals. Thus, the detection of these bacteria can indicate feceal
contamination. The species of Staphylococcus
aureus is frequently related to cases
and outbreaks of food poisoning due to the ability of most strain to produce
enterotoxins. Given the risk of public health and the importance which the
presence of enterotoxins in food products represent, in several countries the
research and the quantification of the species is obligatory and established as
part of the sanitary inspection policies of governmental bodies. Products based
on milk, such as ice cream are currently considered functional ingredients in
relation to health. They contain proteins, sugars, vegetables and/or animal
fats, vitamins A, B1, B2, B6, C, D, and K, calcium, phosphorus and other
essential minerals in a balance proportion. The chemical composition of ice
cream basically comprises the following ingredients: 10% to 17% fat, 8% to 12%
dry detatted extract, 2% to 17% sugars, 0.2% to 0.5% stabilizers and
emulsifiers and 55% to 65% water. (Alvarez et
al., 2008). The growing demand for
food products which are evermore nutritive, accessible and associated with a
low production cost makes whey an important source of nutrients which can be
easily obtained and employed in preparation of large number of food products.
Whey protein concentration (WPC) confers functional and nutritive properties of
interest to yoghurt, cream, butter, ice cream, cream cheese and other products,
which are of the “light” version and differ in terms of cost (Lucena, M.E. et al., 2010). The association of ice
creams with the transmission of diseases has been frequently demonstrated in
countries where strict food control is in place. Ice cream can act as a vehicle
for several pathogens, due to poor pasteurization, contamination during
preparation, inadequate storage, distribution, raw material contamination and
lack of hygiene associated with machines and utensils. Ice cream are not
considered as a serious source of bacterial infection since they are a frozen
food products.
However,
resistance to microorganisms on freezing is highly variables since freezing
does not necessarily provide the death of all microorganisms present and many
survive in different physiological states (Antunes, A.E.C et al., 2008).
1.5 YOGHURT
AND HEALTH
Over the
last few years, food poisoning and food safety have become very tropical
subject, eliciting a great deal of public concern to many people all over the
world. This is a result of emerging food borne pathogens that continue to cause
outbreaks of food borne diseases caused by eating food contaminated with
pathoegenic microorganism on their products (Lefoka, 2009). Yoghurt is one of
the most unique and universal dairy products because of its beneficial and
therapeutic properties. It is considered a main source of high quality fats,
proteins, calcium, phosphorus and potassium along with significant quantities
of several vitamins. Yoghurt has a therapeutic value as it is proved to prevent
the intestinal putrefaction resulting from anaerobic decomposition, prevents
the gastrointestinal disorder, prevents coronary heart disease, reduce the risk
of colon cancer, exerts a hypocholeserolemic effect and produce antibiotics as
acidophilin, lactocidin, nicin and lactoline that inhibit the growth of many
pathogens (Elson and Hass, 2011). Inspite of advanced dairy manufacturing
process, some dairy products as yoghurt may serve as a vehicle of food borne
pathogens various (Fraizer and Westhoff, 2009). Staphylococcus aureus is
one of the most important pathogen in milk or its products (Leloir et al; 2009). The presence of Staph. aureus in the yoghurt could also be caused of unhygienic
processing, handling and packaging (Prescott et al., 2008). Staphylococcus
aureus food poisoning (SFP) is one of
such organism which can be transmitted to human through contaminated and
untreated milk and moil products (Seifu, et
al., 2010). Staph. aureus food
poisoning (SFP) is one the most common food-borne disease resulted from ingestion
Staph. aureus, enterotoxins
(SEs) already performed in food which have super antigenic activity whereas
half of the have been proved to be emetic, representing a potential health,
hazard for consumers (Hennekinne, et al.,
2012). Symptoms of S. aureus food
poisoning have a rapid onset (1 - 6 hours) and often include nausea vomiting,
diarrhea, subnormal temperature and severe abdominal pain (Jablorski and
Bohach, 2011).
1.6 MILK
Milk is
sterile at secretion in the udder but is contaminated by bacteria even its
leaves. Milk has long been referred to as the most perfect food for human from
birth to senility it contains all the nutrients required for a rapid growth and
healthy development of the body, milk also is very important which helps to
build strong bones in the body. Kareishcheese and ice cream are considered the
most popular Egyptian dairy products. Milk and its products have been shown to
be an ideal media for growth and multiplication of many microorganism including
Staphylococci. They are common
vehicles for Staphylococcal food
poisoning, Staphylococcus aureus infection is estimated to be
present in up to 90% of dairy farms and is responsible for 35% of economic loss
in the dairy industry. S.aureus is a
facultative anaerobic gram-positive bacterium. The majority of S. aureus strains are catalase –
positive and coagulase – positive, which forms the bases traditional
identification methodology.
Staphylococcal food
poisoning is a syndrome characteristics by nausea, vomiting, diarrhea, general
malaise and weakness (Ahmed, 2010). Such symptoms appears within 2 – 4 hours
post ingestion of contaminated food. Although the illness is seldom fatal,
complications including dehydration and shock can accompany severe attacks. Staphylococcus aureus is one of the
common agents in bacterial food poisoning outbreaks. It is also a major
causative pathogen of clinical or subclinical mastitis of fairy domestic
ruminants. Rapid and reliable methods for detection of this microorganism in
milk and other foods are needed. When primer set was used for the real-time PCR
detection of S.aureus in milk sample’s without the
pre-enrichment step, samples with target cell numbers greater than (3) CFU/ml
or CFU/g could be detected, indicating the potential quantitative ability of
this real-time PCR assay. The introduction of real-time OCR provides the
opportunity for the rapid detection of pathogens in food and clinical settings.
Apart from saving time, real-time OCR is highly specific, sensitive and offers
the potential for quantification. Approximately, 50 percent of the milk
produced is consumed as fresh or boiled, one sixth as yoghurt or curd and
remaining is utilized for manufacturing of indigenous varieties of milk
products such as ice cream, butter, khoa, paneer, Ralori, Kheer, Burfi and
Gulabjaman (Anjum et al., 2009). Among
all microorganisms, Escherichia coli is frequently contaminating
organism and is reliable indicator of faecal pollution general in insanitary
conditions of water, food milk and other dairy products (Diliello, 2012).
(Martin et al., 2008). Reported two
cases of hemolytic uremic syndrome which provides evidence that raw milk
may be vehicle of transmission of E.coli
0157; H7, both affected person consumed raw milk. The quality of milk is
determined by aspects of composition and hygiene. Due to its complex,
biochemical composition and high water activity, milk serves as an excellent
culture medium for the growth and multiplication of many kinds of
microorganisms (Kumarm V. and R.N. Sinha, 2008).
1.7 FERMENTATION
Fermentation technology is one
of the oldest known methods of food preservation. Fermentation processes
promote the development of essential and safe microflora which play a vital
role in preventing the outgrowth of spoilage and food borne pathogens (Gibbs,
2011). Lactic Acid Bacteria (LAB) are important in much fermentation and the
antagonistic effects of LAB are attributed to some of their biochemical
features. They can utilize carbohydrates and produce organic acids as lactic
acid or acetic acid. The majority of food borne contaminants, either pathogenic
or non-pathogenic is sensitive to these acids and the resulting low pH. They
also produce antibacterial substances such as bacteriocines, hydrogen peroxide,
diacetyl and C02 which may also play part in the antagonism of LAB
on other microorganisms (Maganusson and Schnurer, 2010).
Escherichia coli and Liateria monocytogenes considered as the most common
food borne pathogens that are present in many foods and are able to survive in
fermented milk products. Many Escherichia coli strains are harmless and
are commonly found in the intestinal tract of warm-blooded organisms. Other
strains such as Vero toxin -producing E. coli (VTEG) serotype especially
serotype O157:H7, cause serious poisoning in humans (APHA, 2010). Listeria
monocytogenes is ubiquitous in nature due to its inherent ability to
survive and grow under a wide range of adverse environmental conditions, such
as refrigeration temperatures, high acidity and salinity and reduced water
activity (Gandhi and Chikindas, 2007). According to the Europan Centre for
Disease Control and Prevention, listeriosis was the fifth most common zoonotic
infection in Europe in 2006 (EFSA, 2007) while it accounts for approximately
28% of the deaths resulting from food-borne illnesses in the United States
(Mead et al., 2012).
In food industry, inadequately
cleaned food-processing equipment constitutes a potential source for L.
monocytogenes (Midelet and Carpentier, 2012). Milk and milk products are
frequently incriminated (Rocourt, 2010) among dairy products, yoghurt received
the least attention due to the fact that its high acidity and milk
pasteurization were thought to be effective barriers to the growth of many
pathogens including L. monocytogenes. It is now well established that
the pathogen survives processing and storage of cultured milks including
yoghurt and other dairy products fermented with the same starter (Ribeiro and
Carminati, 2012; Schaak and Marth, 2010). According to De Buyser et al., (2010),
L. monocytogenes was responsible for 10 out of 64 outbreaks implicating
dairy products among which 32.8% were made from pasteurized milk. Moreover,
reported adaptation of the pathogen to acidity (Gahan et al., 2013;
Mazzotta, 2010) is warning us for its possible occurrence in low-acid foods.
This study was conducted to
determine the influence of yoghurt starter culture on the viability of some
pathogenic microorganisms (Escherichia coli and Listeria
monocytogenes) during the storage period of laboratory manufactured yoghurt.
1.8 DRUG RESISTANCE
From the first antibiotic,
penicillin introduced in 1940s which came into wide scale use in the 1950s,
anti-infective drugs to prevent mortality and morbidity arising from infection
have unarguably been one of the most effective health interventions (besides
chlorination of water and sanitation of general) in the history of modern
medicine.
Antibiotic resistance in E.coli
and Staphylococcus aureus
has been globally indentified in isolate from environmental, animal and human source Dromigny J.A (2013).
This is a consequence of the use of antimicrobials medicine and their
application in animal husbandry, which have been brought about phenotypic
changes, often due to chromosomal mutations Erb et al., (2011). Studies have shown that any pathogenic organisms
have developed some degree mechanisms, with the negative impact on veterinary
and human medicine. Yismaw G. (2010). These mechanisms of resistance includes;
the alteration of receptor-binding sites a decreased intake of drugs by
altering the entry or active efflux of the drug, the destruction of drugs,
inactivation of drug and development or resistance metabolic pathways Yismaw G.
(2010). Several studies have revealed that E. coli is resistant to a number
of antibiotics Von Baum H and Reinhard M.
(2009); Gangoue JP et al., (2010) and
Tawfig J.A (2011). Adding to the consequer.ee of microbial resistance to
antibiotic on human health, the contamination of surface water bodies with
resistance bacterial strains from human activities and lives stock operations
has also been reported (Izbal MK and Patel 2000).
Antibiotic therapy can affect
not only the target pathogen but also commensal inhabitants of the human host. The extent of the impact on
non-target microbial populations depends on particular antibiotic used, it's
mode of action and the degree of resistance in the community, sometimes an
imbalance in the commensal gut microbiota due to antibiotic administration can
result in intestinal problems such as antibiotic-associated diarrhoea can
result in intestinal problems such as antibiotic-associated diarrhoea (AAD)
McFarland (2011). An addition concern is the increase in the antibiotic
resistance and the potential spread of resistance and the potential spread of
resistance genes to pathogenic bacteria. Recently, it has been shown that even
short-term antibiotic administration can lead to stabilization of resistant
bacterial population in the human intestine that persist for years (Lafmark et al., 2000).
The spread of resistance
bacteria and resistance genes depends on different factors, but the major pressure
is antibiotics usage. Additionally factors includes the ability of resistant
strains to colonize they gut, their relative fitness, mutation rates and
efficiencies of horizontal transfer of resistance genes. Under the selective
pressure of an antibiotics, a bacterium that acquire a resistance gene is often
conferred with a benefit when this selective pressure is no longer present, the
resistance strain could have a lower fitness compared with its susceptible
counterpart. However, this less competitive done might compensate for this loss
of fitness acquiring a compensatory mutations. The review by (Anderssom and
Hughes, 2010) discusses the fitness costs and mechanism by which the bacterium
can reduce these costs.
A few studies have
investigated the impact of antibiotics on long-term persistence of antibiotic
resistance, the prevalence of Erythromycin-resistant enterococci was
investigated in subject treated with clarithromycin. (Sjolund et al., 2013) using PFGE, it was shown
that three of five subjects carried highly resistant enterococci clones, 1 year
post-administration and these clones carried the ermb gene, conferring
resistance to macrolides such as clarithromycin in another study (Sjolund et al., 2010). Mecrolide
resistant staphylococcus epidermidis
was detected up to 4 years after patient had taken clarithromycin.
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