Health policy can be defined as the "decisions and actions that are undertaken to achieve specific healthcare goals within a society". According to the World Health Organization, an explicit health policy can achieve several things: it defines a vision for the future. There are many categories of health policies, including global health policy, public health policy, mental health policy, health care services policy, insurance policy, personal healthcare policy, pharmaceutical policy, policies related to public health such as vaccination policy, tobacco control policy or breastfeeding promotion policy, they may cover topics of financing and delivery of healthcare, access to care, quality of care, health equity. Health-related policy and its implementation is complex. Conceptual models can help show the flow from health-related policy development to health-related policy and program implementation and to health systems and health outcomes. Policy should be understood as more than a national law or health policy that supports a program or intervention.
Operational policies are the rules, regulations and administrative norms that governments use to translate national laws and policies into programs and services. The policy process encompasses decisions made at a national or decentralized level that affect whether and how services are delivered. Thus, attention must be paid to policies at multiple levels of the health system and over time to ensure sustainable scale-up. A supportive policy environment will facilitate the scale-up of health interventions. There are many topics in the politics and evidence that can influence the decision of a government, private sector business or other group to adopt a specific policy. Evidence-based policy relies on the use of science and rigorous studies such as randomized controlled trials to identify programs and practices capable of improving policy relevant outcomes. Most political debates surround personal health care policies those that seek to reform healthcare delivery, can be categorized as either philosophical or economic.
Philosophical debates center around questions about individual rights and government authority, while economic topics include how to maximize the efficiency of health care delivery and minimize costs. The modern concept of healthcare involves access to medical professionals from various fields as well as medical technology, such as medications and surgical equipment, it involves access to the latest information and evidence from research, including medical research and health services research. In many countries it is left to the individual to gain access to healthcare goods and services by paying for them directly as out-of-pocket expenses, to private sector players in the medical and pharmaceutical industries to develop research. Planning and production of health human resources is distributed among labour market participants. Other countries have an explicit policy to ensure and support access for all of its citizens, to fund health research, to plan for adequate numbers and quality of health workers to meet healthcare goals.
Many governments around the world have established universal health care, which takes the burden of healthcare expenses off of private businesses or individuals through pooling of financial risk. There are a variety of arguments against universal healthcare and related health policies. Healthcare is an important part of health systems and therefore it accounts for one of the largest areas of spending for both governments and individuals all over the world. Many countries and jurisdictions integrate a human rights philosophy in directing their healthcare policies; the World Health Organization reports that every country in the world is party to at least one human rights treaty that addresses health-related rights, including the right to health as well as other rights that relate to conditions necessary for good health. The United Nations' Universal Declaration of Human Rights asserts that medical care is a right of all people: UDHR Article 25: "Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing and medical care and necessary social services, the right to security in the event of unemployment, disability, old age or other lack of livelihood in circumstances beyond his control."In some jurisdictions and among different faith-based organizations, health policies are influenced by the perceived obligation shaped by religious beliefs to care for those in less favorable circumstances, including the sick.
Other jurisdictions and non-governmental organizations draw on the principles of humanism in defining their health policies, asserting the same perceived obligation and enshrined right to health. In recent years, the worldwide human rights organization Amnesty International has focused on health as a human right, addressing inadequate access to HIV drugs and women's sexual and reproductive rights including wide disparities in maternal mortality within and across countries; such increasing attention to health as a basic human right has been welcomed by the leading medical journal The Lancet. There remains considerable controversy regarding policies on who would be paying the costs of medical care for all people and under what circumstances. For example, government spending on healthcare is sometimes used as a global indicator of a government's commitment to the health of its people. On the other hand, one school of thought emerging from the United States rejects the notion of health care financing through taxpayer funding as incompatible with the
Biological hazards known as biohazards, refer to biological substances that pose a threat to the health of living organisms that of humans. This can include samples of a virus or toxin that can affect human health, it can include substances harmful to other animals. The term and its associated symbol are used as a warning, so that those exposed to the substances will know to take precautions; the biohazard symbol was developed in 1966 by Charles Baldwin, an environmental-health engineer working for the Dow Chemical Company on the containment products. It is used in the labeling of biological materials that carry a significant health risk, including viral samples and used hypodermic needles. In Unicode, the biohazard symbol is U+2623. Bio hazardous agents are classified for transportation by UN number: Category A, UN 2814 – Infectious substance, affecting humans: An infectious substance in a form capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals when exposure to it occurs.
Category A, UN 2900 – Infectious substance, affecting animals: An infectious substance, not in a form capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans and animals when exposure to themselves occurs. Category B, UN 3373 – Biological substance transported for diagnostic or investigative purposes. Regulated Medical Waste, UN 3291 – Waste or reusable material derived from medical treatment of an animal or human, or from biomedical research, which includes the production and testing; the United States Centers for Disease Control and Prevention categorizes various diseases in levels of biohazard, Level 1 being minimum risk and Level 4 being extreme risk. Laboratories and other facilities are categorized as P1 through P4 for short. Biohazard Level 1: Bacteria and viruses including Bacillus subtilis, canine hepatitis, Escherichia coli, varicella, as well as some cell cultures and non-infectious bacteria. At this level precautions against the biohazardous materials in question are minimal, most involving gloves and some sort of facial protection.
Biohazard Level 2: Bacteria and viruses that cause only mild disease to humans, or are difficult to contract via aerosol in a lab setting, such as hepatitis A, B, C, some influenza A strains, Lyme disease, mumps, scrapie, dengue fever, HIV. Routine diagnostic work with clinical specimens can be done safely at Biosafety Level 2, using Biosafety Level 2 practices and procedures. Research work can be done in a BSL-2 facility, using BSL-3 procedures. Biohazard Level 3: Bacteria and viruses that can cause severe to fatal disease in humans, but for which vaccines or other treatments exist, such as anthrax, West Nile virus, Venezuelan equine encephalitis, SARS virus, MERS coronavirus, tuberculosis, Rift Valley fever, Rocky Mountain spotted fever, yellow fever, malaria. Biohazard Level 4: Viruses that cause severe to fatal disease in humans, for which vaccines or other treatments are not available, such as Bolivian hemorrhagic fever, Marburg virus, Ebola virus, Lassa fever virus, Crimean–Congo hemorrhagic fever, other hemorrhagic diseases and rishibola.
Variola virus is an agent, worked with at BSL-4 despite the existence of a vaccine, as it has been eradicated. When dealing with biological hazards at this level the use of a positive pressure personnel suit, with a segregated air supply, is mandatory; the entrance and exit of a Level Four biolab will contain multiple showers, a vacuum room, an ultraviolet light room, autonomous detection system, other safety precautions designed to destroy all traces of the biohazard. Multiple airlocks are employed and are electronically secured to prevent both doors opening at the same time. All air and water service going to and coming from a Biosafety Level 4 lab will undergo similar decontamination procedures to eliminate the possibility of an accidental release. There are no bacteria classified at this level; the biohazard symbol was developed by the Dow Chemical Company in 1966 for their containment products. According to Charles Baldwin, an environmental-health engineer who contributed to its development: "We wanted something, memorable but meaningless, so we could educate people as to what it means."
In an article he wrote for Science in 1967, the symbol was presented as the new standard for all biological hazards. The article explained that over 40 symbols were drawn up by Dow artists, all of the symbols investigated had to meet a number of criteria: Striking in form in order to draw immediate attention; the chosen symbol scored the best on nationwide testing for memorability. The design was dropped in the succeeding amendment. However, various US states adopted the specification for their state code. There are four circles within the symbol, signifying the chain of infection. Agent: The type of microorganism, that causes infection or hazardous condition. Host: The organism in which the microorganism Infect; the new host must be susceptible. Source: The host from which the microorganism originate; the carrier host might not show symptoms. Transmission: The means of transmission direct or in
Within the framework of the World Health Organization's definition of health as a state of complete physical and social well-being, not the absence of disease or infirmity, reproductive health, or sexual health/hygiene, addresses the reproductive processes and system at all stages of life. UN agencies claim sexual and reproductive health includes physical, as well as psychological well-being vis-a-vis sexuality. Reproductive health implies that people are able to have a responsible and safer sex life and that they have the capability to reproduce and the freedom to decide if, when and how to do so. One interpretation of this implies that men and women ought to be informed of and to have access to safe, effective and acceptable methods of birth control. Individuals do face inequalities in reproductive health services. Inequalities vary based on socioeconomic status, education level, ethnicity and resources available in their environment, it is possible for example, that low income individuals lack the resources for appropriate health services and the knowledge to know what is appropriate for maintaining reproductive health.
The WHO assessed in 2008 that "Reproductive and sexual ill-health accounts for 20% of the global burden of ill-health for women, 14% for men." Reproductive health is a part of rights. According to the United Nations Population Fund, unmet needs for sexual and reproductive health deprive women of the right to make "crucial choices about their own bodies and futures", affecting family welfare. Women bear and nurture children, so their reproductive health is inseparable from gender equality. Denial of such rights worsens poverty. Adolescent health creates a major global burden and has a great deal of additional and diverse complications compared to adult reproductive health such as early pregnancy and parenting issues, difficulties accessing contraception and safe abortions, lack of healthcare access, high rates of HIV and sexually transmitted infections, mental health issues; each of those can be affected by outside political and socio-cultural influences. For most adolescent females, they have yet to complete their body growth trajectories, therefore adding a pregnancy exposes them to a predisposition to complications.
These complications range from anemia, malaria, HIV and other STI's, postpartum bleeding and other postpartum complications, mental health disorders such as depression and suicidal thoughts or attempts. In 2016, adolescent birth rates between the ages of 15-19 was 45 per 1000. In 2014, 1 in 3 experienced sexual violence, there more than 1.2 million deaths. The top three leading causes of death in females between the ages of 15-19 are maternal conditions 10.1%, self-harm 9.6%, road conditions 6.1%. The causes for teenage pregnancy are diverse. In developing countries, young women are pressured to marry for different reasons. One reason is to bear children to help with work, another on a dowry system to increase the families income, another is due to prearranged marriages; these reasons tie back to financial needs of girls' family, cultural norms, religious beliefs and external conflicts. Adolescent pregnancy in developing countries, carries increased health risks, contributes to maintaining the cycle of poverty.
The availability and type of sex education for teenagers varies in different parts of the world. LGBT teens may suffer additional problems if they live in places where homosexual activity is disapproved and/or illegal. Ninety nine percent of maternal deaths occur in developing countries and in 25 years, maternal mortality globally dropped to 44%. Statistically, a woman's chance of survival during childbirth is tied to her social economic status, access to healthcare, where she lives geographically, cultural norms. To compare, a woman dies of complications from childbirth every minute in developing countries versus a total of 1% of total maternal mortality deaths in developed countries. Women in developing countries have little access to family planning services, different cultural practices, have lack of information, birthing attendants, prenatal care, birth control, postnatal care, lack of access to health care and are in poverty. In 2015, those in low-income countries had access to antenatal care visits averaged to 40% and were preventable.
All these reasons lead to an increase in the Maternal Mortality Ratio. One of the international Sustainable Development Goals developed by United Nations is to improve maternal health by a targeted 70 deaths per 100,000 live births by 2030. Most models of maternal health encompass family planning, preconception and postnatal care. All care after childbirth recovery is excluded, which includes pre-menopause and aging into old age. During childbirth, women die from severe bleeding, high blood pressure during pregnancy, delivery complications, or an unsafe abortion. Other reasons can be regional such as complications related to diseases such as malaria and AIDS during pregnancy; the younger the women is when she gives birth, the more at risk her and her baby is for complications and mortality. There is a significant relationship between the quality of maternal services made available and the greater financial standings of a country. Sub-Saharan Africa and South Asia exem
Health care reform
Health care reform- is for the most part, governmental policy that affects health care delivery in a given place. Health care reform attempts to: Broaden the population that receives health care coverage through either public sector insurance programs or private sector insurance companies Expand the array of health care providers consumers may choose among Improve the access to health care specialists Improve the quality of health care Give more care to citizens Decrease the cost of health care In the United States, the debate regarding health care reform includes questions of a right to health care, fairness, sustainability and amounts spent by government; the mixed public-private health care system in the United States is the most expensive in the world, with health care costing more per person than in any other nation, a greater portion of gross domestic product is spent on it than in any other United Nations member state except for East Timor. Both Hawaii and Massachusetts have implemented some incremental reforms in health care, but neither state has complete coverage of its citizens.
For example, data from the Kaiser Family Foundation shows that 5% of Massachusetts and 8% of Hawaii residents are uninsured. To date, The U. S. Uniform Law Commission, sponsored by the National Conference of Commissioners on Uniform State Laws has not submitted a uniform act or model legislation regarding health care insurance or health care reform. Healthcare was reformed in 1948 after the Second World War, broadly along the lines of the 1942 Beveridge Report, with the creation of the National Health Service or NHS, it was established as part of a wider reform of social services and funded by a system of National Insurance, though receipt of healthcare was never contingent upon making contributions towards the National Insurance Fund. Private health care was not abolished but had to compete with the NHS. About 15% of all spending on health in the UK is still funded but this includes the patient contributions towards NHS provided prescription drugs, so private sector healthcare in the UK is quite small.
As part of a wider reform of social provision it was thought that the focus would be as much about the prevention of ill-health as it was about curing disease. The NHS for example would distribute baby formula milk fortified with vitamins and minerals in an effort to improve the health of children born in the post war years as well as other supplements such as cod liver oil and malt. Many of the common childhood diseases such as measles and chicken pox were eradicated with a national program of vaccinations; the NHS has been through many reforms since 1974. The Conservative Thatcher administrations attempted to bring competition into the NHS by developing a supplier/buyer role between hospitals as suppliers and health authorities as buyers; this necessitated the detailed costing of activities, something which the NHS had never had to do in such detail, some felt was unnecessary. The Labour Party opposed these changes, although after the party became New Labour, the Blair government retained elements of competition and extended it, allowing private health care providers to bid for NHS work.
Some treatment and diagnostic centres are now funded under contract. However, the extent of this privatisation of NHS work is still small; the administration committed more money to the NHS raising it to the same level of funding as the European average and as a result, there was large expansion and modernisation programme and waiting times improved. The government of Gordon Brown proposed new reforms for care in England. One is to take the NHS back more towards health prevention by tackling issues that are known to cause long term ill health; the biggest of these is related diseases such as diabetes and cardio-vascular disease. The second reform is to make the NHS a more personal service, it is negotiating with doctors to provide more services at times more convenient to the patient, such as in the evenings and at weekends; this personal service idea would introduce regular health check-ups so that the population is screened more regularly. Doctors will give more advice on ill-health prevention and so tackle problems before they become more serious.
Waiting times, which fell under Blair are in focus. A target was set from December 2008, to ensure that no person waits longer than 18 weeks from the date that a patient is referred to the hospital to the time of the operation or treatment; this 18-week period thus includes the time to arrange a first appointment, the time for any investigations or tests to determine the cause of the problem and how it should be treated. An NHS Constitution was published which lays out the legal rights of patients as well as promises the NHS strives to keep in England. Numerous healthcare reforms in Germany were legislative interventions to stabilise the public health insurance since 1983. 9 out of 10 citizens are publicly insured, only 8% privately. Health care in Germany, including its industry and all services, is one of the largest sectors of the German economy; the total expenditure in health economics of Germany was about 287.3 billion euro in 2010, equivalent to 11.6 percent of the gross domestic product this year and about 3,510 euro per capita.
Direct inpatient and outpatient care equal just about a quarter of the entire expenditure - depending on the perspective. Expenditure on pharmaceutical drugs is twice the amount of those for the entire hospi
Euthenics is the study of the improvement of human functioning and well-being by improvement of living conditions. Affecting the "improvement" through altering external factors such as education and the controllable environment, including the prevention and removal of contagious disease and parasites, education regarding employment, home economics and housing. Rose Field notes of the definition in a May 23, 1926 New York Times article, "the simplest being efficient living". A right to environment; the Flynn effect has been cited as an example of euthenics. Another example is the steady increase in body size in industrialized countries since the beginning of the 20th century. Euthenics is not interpreted to have anything to do with changing the composition of the human gene pool by definition, although everything that affects society has some effect on who reproduces and who does not; the term was derived in the late 19th century from the Greek verb eutheneo, εὐθηνέω. From the Greek Euthenia, Εὐθηνία.
Good state of the body: prosperity, good fortune, abundance.—Herodotus. The opposite of Euthenia is Penia, Πενία the personification of need. Ellen H. Swallow Richards was one of the first writers to use the term, in The Cost of Shelter, with the meaning "the science of better living", it is unclear if any of the study programs of euthenics completely embraced Richards' multidisciplinary concept, though several nuances remain today that of interdisciplinarity. After Richards' death in 1911, Julia Lathrop —one of Vassar's most distinguished alumnae—continued to promote the development of an interdisciplinary program in euthenics at the college. Lathrop soon teamed with alumna Minnie Cumnock Blodgett, who with her husband, John Wood Blodgett, offered financial support to create a program of euthenics at Vassar College. Curriculum planning, suggested by Vassar president Henry Noble MacCracken in 1922, began in earnest by 1923, under the direction of Professor Annie Louise Macleod. According to Vassar's chronology entry for March 17, 1924, "the faculty recognized euthenics as a satisfactory field for sequential study.
A Division of Euthenics was authorized to offer a multidisciplinary program focusing the techniques and disciplines of the arts and social sciences on the life experiences and relationships of women. Students in euthenics could take courses in horticulture, food chemistry and statistics, child study, economic geography, hygiene, public health and domestic architecture and furniture. With the new division came the first major in child study at an American liberal arts college."For example, a typical major in child study in euthenics includes introductory psychology, laboratory psychology, applied psychology, child study and social psychology in the Department of Psychology. The Vassar Summer Institute of Euthenics accepted its first students in June 1926. Created to supplement the controversial euthenics major which began February 21, 1925, it was located in the new Minnie Cumnock Blodgett Hall of Euthenics; some Vassar faculty members contentiously "believed the entire concept of euthenics was vague and counter-productive to women's progress."Having overcome a lukewarm reception, Vassar College opened its Minnie Cumnock Blodgett Hall of Euthenics in 1929.
Dr. Ruth Wheeler took over as director of euthenics studies in 1924. Wheeler remained director until Mary Shattuck Fisher Langmuir succeeded her in 1944, until 1951; the college continued for the 1934–35 academic year its successful cooperative housing experiment in three residence halls. Intended to help students meet their college costs by working in their residences. For example, in Main, students earned $40 a year by doing light work such as cleaning their rooms. In 1951, Katharine Blodgett Hadley donated $400,000, through the Rubicon Foundation, to Vassar to help fund operating deficits in the current and succeeding years and to improve faculty salaries."Discontinued for financial reasons, the Vassar Summer Institute for Family and Community Living, founded in 1926 as the Vassar Summer Institute of Euthenics, held its last session, July 2, 1958. This was the first and last session for the institute's new director, Dr. Mervin Freedman." Elmira College is noted as the oldest college still in existence which granted degrees to women which were the equivalent of those given to men.
Elmira College became coeducational in all of its programs in 1969. A special article was written in the December 12, 1937 New York Times, quoting recent graduates of Elmira College, urging for courses in colleges for men on the care of children. Reporting that "preparation for the greatest of all professions, that of motherhood and child-training, is being given the students at Elmira College in the Nursery School, Conducted as part
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the
Mycobacterium tuberculosis is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, as a result, M. tuberculosis can appear either Gram-negative or Gram-positive. Acid-fast stains such as Ziehl-Neelsen, or fluorescent stains such as auramine are used instead to identify M. tuberculosis with a microscope. The physiology of M. tuberculosis is aerobic and requires high levels of oxygen. A pathogen of the mammalian respiratory system, it infects the lungs; the most used diagnostic methods for tuberculosis are the tuberculin skin test, acid-fast stain and polymerase chain reaction. The M. tuberculosis genome was sequenced in 1998. M. tuberculosis is part of a complex that has at least 9 members: M. tuberculosis sensu stricto, M. africanum, M. canetti, M. bovis, M. caprae, M. microti, M. pinnipedii, M. mungi, M. orygis.
It requires oxygen to grow, does not produce spores, is nonmotile. M. tuberculosis divides every 15–20 hours. This is slow compared with other bacteria, which tend to have division times measured in minutes, it is a small bacillus that can withstand weak disinfectants and can survive in a dry state for weeks. Its unusual cell wall is rich in lipids such as mycolic acid and is responsible for its resistance to desiccation and is a key virulence factor. Other bacteria are identified with a microscope by staining them with Gram stain. However, the mycolic acid in the cell wall of M. tuberculosis does not absorb the stain. Instead, acid-fast stains such as Ziehl-Neelsen stain, or fluorescent stains such as auramine are used. Cells are curved rod-shaped and are seen wrapped together, due to the presence of fatty acids in the cell wall that stick together; this appearance is referred to like strands of cord that make up a rope. M. tuberculosis is characterized in tissue by caseating granulomas containing Langhans giant cells, which have a "horseshoe" pattern of nuclei.
M. tuberculosis can be grown in the laboratory. Compared to other studied bacteria, M. tuberculosis has a remarkably slow growth rate, doubling once per day. Used media include liquids such as Middlebrook 7H9 or 7H12, egg-based solid media such as Lowenstein-Jensen, solid agar-based such as Middlebrook 7H11 or 7H10. Visible colonies require several weeks to grow on agar plates, it is distinguished from other mycobacteria by its production of niacin. Other tests to confirm its identity include gene probes and MALDI-TOF. Humans are the only known reservoirs of M. tuberculosis. A misconception is that M. tuberculosis can be spread by shaking hands, making contact with toilet seats, sharing food or drink, sharing toothbrushes, or kissing. It can only be spread through air droplets originating from a person who has the disease either coughing, speaking, or singing; when in the lungs, M. tuberculosis is phagocytosed by alveolar macrophages, but they are unable to kill and digest the bacterium. Its cell wall prevents the fusion of the phagosome with the lysosome, which contains a host of antibacterial factors.
M. tuberculosis blocks the bridging molecule, early endosomal autoantigen 1. The bacteria multiply unchecked within the macrophage; the bacteria carry the UreC gene, which prevents acidification of the phagosome. In addition, production of the diterpene isotuberculosinol prevents maturation of the phagosome; the bacteria evade macrophage-killing by neutralizing reactive nitrogen intermediates. Protective granulomas are formed due to the production of cytokines and upregulation of proteins involved in recruitment. Granulotomatous lesions are important in both regulating the immune response and minimizing tissue damage. Moreover, T cells help maintain Mycobacterium within the granulomas; the ability to construct M. tuberculosis mutants and test individual gene products for specific functions has advanced the understanding of its pathogenesis and virulence factors. Many secreted and exported proteins are known to be important in pathogenesis. Aerolysin is a virulence factor of the pathogenic bacterium Aeromonas hydrophila.
Resistant strains of M. tuberculosis have developed resistance to more than one TB drug, due to mutations in their genes. Typing of strains is useful in the investigation of tuberculosis outbreaks, because it gives the investigator evidence for or against transmission from person to person. Consider the situation where person A has tuberculosis and believes he acquired it from person B. If the bacteria isolated from each person belong to different types transmission from B to A is definitively disproved; until the early 2000s, M. tuberculosis strains were typed by pulsed field gel electrophoresis. This has now been superseded by variable numbers of tandem repeats, technically easier to perform and allows better discrimination between strains; this method makes use of the presence of repeated DNA sequences within the M. tuberculosis genome. Three generations of VNTR typing for M. tuberculosis are noted. The first scheme, called exact tandem repeat, used only five loci, but the resolution afforded by these five loci was not as good as PFGE.
The second scheme, called mycobacterial interspersed repetitive unit, had discrimination as good as PFGE. The third