ISOLATION AND SENSITIVITY OF BACTERIA ISOLATE FROM VAGINAL DISCHARGE TO ANTIBIOTICS

CHAPTER TWO

2.1 LITERATURE REVIEW

2.2 Origin of antibiotic resistance

Antibiotic resistance was reported to occur when a drug loses its ability to inhibit bacterial growth effectively. Bacteria become ‘resistant’ and continue to multiply in the presence of therapeutic levels of the antibiotics. Bacteria, which replicate even in the presence of the antibiotics, are called resistant bacteria.

Antibiotics are usually effective against them, but when the microbes become less sensitive or resistant, it requires a higher than the normal concentration of the same drug to have an effect. The emergence of antimicrobial resistance was observed shortly after the introduction of new antimicrobial compounds. Antibiotic resistance can occur as a natural selection process where nature empowers all bacteria with some degree of low-level resistance. For example, one study confirmed that ampicillin and tetracycline that were commonly used in yesteryears, but now have no longer role in treating non-cholera diarrhea disease in Thailand (Hoge et al.,1998). At the same time, another study conducted in Bangladesh showed the effectiveness of the same drugs in treating them effectively (Rahman et al., 2017). In fact, resistance was documented even before the beginning of the usage of the antibiotics in fighting the infection (Abraham and Chain, 1940). Non-judicial use of antibiotic is responsible for making microbes resistant. Since the introduction of sulfonamides in 1937, the development of specific mechanisms of resistance had provoked their therapeutic use. However, sulfonamide resistance was reported in the 1930s, which reveals the same mechanism of resistance that still operates even now, more than 80 years later). Within six years of the production of the aminoglycosides, aminoglycoside-resistant strains of Staphylococcus aureus was developed (Gootz , 1990). Introduced in 1961, Methicillin was the first of the semisynthetic penicillinase-resistant penicillin to target strains of penicillinase-producing Staphylococcus aureus. However, resistance to methicillin was reported soon after its initiation (Br Med , 1961). Further, although fluoroquinolones were introduced for the treatment of Gram-negative bacterial diseases in the 1980s, fluoroquinolones resistance later revealed that these drugs were also used to treat Gram-positive infections. Most recently, the clinical isolates of Vancomycin-resistant Staphylococcus aureus (VRSA) were found in 2002, after 44 years of Vancomycin introduction to the market. Antibiotics used in agriculture are often the same or similar to antibiotic compounds used clinically (McEwen and FeDorka-Cray , 2002), this over-usage could also invite drug resistance. The food chain can be considered the main route of transmission of antibiotic-resistant bacteria between animal and human populations (Witte , 1998). In some developed countries, animals receive antibiotics in their food, water, or parenterally which may be responsible for carrying microbe resistance to that specific antibiotic (McEwen and Fe Dorka-Cray, 2002). For example, the use of antibiotics in cattle feed as growth promoters increase antibiotic resistance (Levy , 1993). Recent evidence suggests that poultry or pork might be a possible source of quinolone resistant-Escherichia coli in the rural villages in Barcelona, where one-fourth of children were found to be fecal carriers of these organisms. However, these kids were never exposed to quinolones (Garan, et al.,1998)

2.3 Development of antibiotic resistance

Antibiotics fight to eliminate bacteria. Hence, bacteria tend to have a natural process that encourages resistance. The resistance process occurs via gene level mutations. (Laxminarayan and Brown, 2001). Antibiotics induce selective pressure and the genes act in association with selective pressure (Levy, 1993). Bacteria possess the quality to directly transfer genetic material between each other by transferring plasmids, which signifies that natural selection is not the only mechanism by which resistance evolves. Broad spectrum antibiotics are prescribed in hospitals as a solution for nosocomial infections; however, it increases resistance (Lowey, 2003).

Antibiotics can generally eliminate the majority of bacteria in a colony. However, there may exist a different colony of bacteria that are genetically mutated which can lead to resistance (Alanis, 2005). The level of antibiotic-resistant infections was found to be strongly correlated with the degree of antibiotic consumption (Goossens, et al., 2005). Development of resistance may also likely to occur if users fail to take their full course of prescribed antibiotic treatment. The bacteria subsequently remain untouched gaining more strength against the antibiotics (Levy, 1993). Bacteria may collect multiple resistance traits over time and can become resistant to multiple classes of antibiotics (Avon, et al., 2001). For example, resistance was found in Staphylococci from the chromosomal mutations, ineffective transport of aminoglycosides into the bacteria as well as enzyme modification (Lowey, 2003). A single antibiotic may not only select resistance to one particular drug. Resistance can occur with other structurally related compounds of the same class. For example, resistance to tetracycline may incur resistance to oxytetracycline, chlortetracycline, doxycycline, and minocycline (Chopra and Roberts, 2001). Antimicrobials possessed resistance genes that defend their antimicrobial products and these genes developed antibiotic resistance even long ago before the antibiotic started working for treatment purpose (Chadwick and Goode, 1997).

2.4 Colonization and Transmission of urinary tract infection (UTI)

Urinary tract is regularly flushed with sterile urine and its acidity, there it makes difficulty for microbes to access and establish here but anterior urethra is inhabited by relatively constant flora such as Staphylococcus epidermidis, Enterococcus faecalis and some Alpha-hemolytic streptococci (Pubus and Enderdonk, 1999)

Occasionally, some enteric bacteria like E. coli, Proteusand corynebacteria may be found there. Vagina is an available space for certain microbes. It is colonized with Corynebacteria, Staphylococci, Streptococci, E. coli, and Doderlein’s bacillus (Lactobacillus acidophilus).

. During reproductive lifevaginal epithelium contains glycogenwhich is metabolizedby Lactobacillus acidophilus. The lactic acid and other products of metabolism inhibit colonization of offendingagents in that areaand allow only Lactobacillus acidophilus and some otherlactic acid producingspecies to grow(Noskan et at., 2005)

Oral contraceptives, steroids, and antibiotics disrupt either the normal flora or naturally acidic Phof the urinary tract. Reduction in lactic acid leads to high pH of vaginal epithelium which encouragesother offending agents togrow and resultsin embarrassing vaginal odour (sometimes described as smelling “fishy”), abnormal discharge (often thin and white-grey in colour) and discomfort (normally irritation or soreness in and around vagina). Vaginaldischarge is a termgiven to the biological fluids contained withinor expelled from vagina.Normally this discharge demonstrates various phases of menstrual cycle but it may also be due to vaginal infections. That is why vaginal infectionis checked bythe presence orabsence of these offending microorganisms in a vaginal discharge. The three major kinds ofvaginitis are vaginalcandidiasis, bacterial vaginosis(BV) andTrichomoniasis. At a time, a woman may have any vaginal co-infections. Untreated vaginal infection may lead to any complication especially in pregnant women (Momoh et tal., 2007)

2.5 Consequence of antibiotic resistance

Antibiotic resistant organisms are known as superbugs. These are not only a laboratory concern but have become a global threat responsible for high death tolls and life-threatening infections (Lipp, et al., 2002). Consequences of these infections are aggravated enormously in volatile situations such as civil unrest, violence, famine and natural disaster (Fact Sheet, 2015). World Health Organization (WHO) (Fact Sheet, 2015) has warned that a post-antibiotic era will result in frequent infections and small injuries may result in death if we fail to act against antibiotic resistance; Multi-drug resistant bacteria causing more deaths worldwide. More than 63,000 patients from the United States of America (USA) die every year from hospital-acquired bacterial infections (Aminov and MackieI, 2007). Every year, an estimated 25,000 patients die due to multiple drug resistance (MDR) bacterial infections in Europe (Freire-Moran ,et al., 2011). Many countries are facing the burden of nosocomial Staphylococcus aureus (S. Aureus) infections as waves of clonal dissemination. Methicillin-resistant Staphylococcus aureus (MRSA) strains are rapidly spreading globally (Lowey, 2003). Estimated costs due to multidrug-resistant bacterial infection might result in extra healthcare costs and productivity losses (Freire-moran, et al., 2011). It has been a standard practice for most of the pharmaceutical companies to distribute antibiotics that may no longer be effective or lacking regulatory approval (Levy and Marshall, 2004). Evidence shows that increased antibiotic use may result in a positive association with a higher prevalence of resistant microorganisms, while reduced antibiotic use showed lower resistance rates. There is clear evidence that patients historically treated with antibiotics are more likely to have antibiotic resistance (Laximinarayan R and Brown, 2001). Further, re-administration of antibiotics from the initial cycle accelerates resistance mechanisms (Anderson, 1991). Antibiotics encourage selective pressure for bacteria to evolve when administered frequently or irrationally. Individuals and states play a role in the evolution of antibiotic resistance (Laxminarayan and Brown, 2001). For example, Clarithromycin consumption and its resistance similarly increased fourfold in Japan between 1993 and 2000 in comparison to other countries (Perez et al., 2002).

2.6 Regulatory issues related to antibiotic resistance

Congruent international management guidelines for daily antibiotic practices are yet unavailable. Hence, regulatory guidelines vary in different countries. Some countries have acted swiftly offering guidance e.g. United Kingdom, while other nations have yet to move toward interventions. The WHO has offered recommendations such as children in developing countries that antibiotics should only be used for the treatment of severe bloody diarrhea and cholera (WHO. CAH. Geneva, 1995). Since the beginning of the industrial revolution, we have dumped increase amounts of organic and inorganic toxins into streams, rivers, oceans, land, and air. In the personal care industry, there are insufficient guidelines for monitoring the home hygiene products which are likely to cause more risk for resistance because these products contain a high concentration of antibacterial ingredients (Laxminarayan and Brown, 2001).

With an abundance of evidence, there is no scope to ignore global antibiotic resistance. Antibiotic resistance can be more prevalent where antibiotic consumption is found to be higher. Lack of regulation and control in using antibiotics is prominent and needs to be targeted at a global capacity. Developing nations are at the greatest risk. Low prices of antibiotics, ease of availability and unnecessary use of antibiotics are causing more burdens in developing countries (Levy and Marshall, 2004). Antibiotic use is relatively uncontrolled among the countries where there is no universal health coverage for its citizens (Zaman and Hossain, 2017). Hence, irrational use of drugs has become a major concern. According to a study done in the United Kingdom, among the participants, 11.3% reported that they did not finish their last antibiotic course as prescribed. When asked about the reason why not comply with the course, 65% of the respondents stated that they felt better or forgot to take an antibiotic in time (Woodhead and Finch, 2007).

We are all affected by this multi-face ted public health issue. An all-encompassing problem that doesn’t just pertain to clinical personnel and microbiologists, but service personnel, industry stakeholders, specialists and the general public. We have to take necessary steps to tackle this complicated challenge. Social awareness, motivation, commitment in responsible sectors, stringent rules and regulation have to be prioritized. Further, we need the coupled action for the proper Urinary Tract Infection(UTi)lization of antibiotics, best management practices, and behavioral shifts across all industries that we can then combat against this public health burden. Application of modern technology can help the patient to take the antibiotic timely (Zaman , 2017). At present, the most notorious superbug is the Gram-positive organism Staphylococcus aureus (Lowey , 2003). This pathogen is frightening as its resistance to antibiotics is dramatically increasing. With an intimate history so closely tied to humans, Staphylococcus aureus is feared and at times, misunderstood (Lowey , 2003). These tendencies are causing higher resistance rates resulting in imminent hazards in human health. Notably, irrationality is observed in using antibiotics in livestock. Animals are given antibiotics for faster growth and disease prophylaxis. Strict and enforced regulations in the agricultural industry are needed to curb the harmful ripple effects.

Treatments for bacterial infections are becoming intensified every day. Infections remain as antibiotics gain resistance; treatment failure is common due to antibiotic resistance and multi-drug resistance, for e.g. tuberculosis. Newer and effective antibiotics that have no known resistance to bacteria are in high demand. Alternative treatment procedures are under consideration to fight bacterial infection. Passive immunization or administration of antibodies to non-immunized to prevent bacterial infections have been found effective (Keller and Stiehn, 2000). Another effective intervention is phage therapy, whereas bacteriophages are used to treat pathogenic bacterial infections (Monk et al., 2010). Many newer classes of antimicrobials to fight antibiotic resistance are in the pipeline for clinical trials (Devasahayam et al., 2010). Intervention strategies are aimed not only at targets but rather at the biological networks that may help to create new antibacterial therapies (Kohanski et al., 2010). Combination therapies coupling antibiotics with antibiotic-enhancing phage have demonstrated the potential to be a promising antimicrobial intervention (Aminov, 2010).

2.7 Mechanism of antimicrobial resistance

There are number of ways by which microorganisms are resistant to antimicrobial agents. These include:

1. Bacteria produce enzymes which destroy the antimicrobial agents before it reaches its targets e.g. Beta lactamase enzyme hydrolyses beta lactam drugs which develop resistance.

2. Impermeable cell for antimicrobial drugs e.g. Gram negative bacteria may become resistant to Beta lactam antibiotics by developing permeability barrier.

3. Mutation e.g. Ribosome methylation of ribosomal RNA develop macrolide resistant.

4. Bacterial efflux pump that expels antimicrobial drugs from cell before it can reach its targets.

5. Specific Metabolic pathways in the bacteria are genetically altered so that antibacterial agents cannot exert an effect. (Marie et al., 2005; Rice et al., 2007).