The Mantoux tuberculin skin test is often used to screen people at high risk for TB. Those who have been previously immunized may have a false-positive test result. The test may be falsely negative in those with sarcoidosis, Hodgkin's lymphoma, malnutrition, and most notably, active tuberculosis. Interferon gamma release assays, on a blood sample, are recommended in those who are positive to the Mantoux test. These are not affected by immunization or most environmental mycobacteria, so they generate fewer false-positive results. However, they are affected by "M. szulgai", "M. marinum", and "M. kansasii". IGRAs may increase sensitivity when used in addition to the skin test, but may be less sensitive than the skin test when used alone.

Diagnosing active tuberculosis based only on signs and symptoms is difficult, as is diagnosing the disease in those who are immunosuppressed. A diagnosis of TB should, however, be considered in those with signs of lung disease or constitutional symptoms lasting longer than two weeks. A chest X-ray and multiple sputum cultures for acid-fast bacilli are typically part of the initial evaluation. Interferon-γ release assays and tuberculin skin tests are of little use in the developing world. Interferon gamma release assays (IGRA) have similar limitations in those with HIV.

A definitive diagnosis of TB is made by identifying "M. tuberculosis" in a clinical sample (e.g., sputum, pus, or a tissue biopsy). However, the difficult culture process for this slow-growing organism can take two to six weeks for blood or sputum culture. Thus, treatment is often begun before cultures are confirmed.

Nucleic acid amplification tests and adenosine deaminase testing may allow rapid diagnosis of TB. These tests, however, are not routinely recommended, as they rarely alter how a person is treated. Blood tests to detect antibodies are not specific or sensitive, so they are not recommended.

A study conducted on 452 patients revealed that the genotype responsible for higher IL-10 expression makes HIV infected people more susceptible to tuberculosis infection. Another study on HIV-TB co-infected patients also concluded that higher level of IL-10 and IL-22 makes TB patient more susceptible to Immune reconstitution inflammatory syndrome (IRIS). It is also seen that HIV co-infection with tuberculosis also reduces concentration of immunopathogenic matrix metalloproteinase (MMPs) leading to reduced inflammatory immunopathology.

It is currently recommended that HIV-infected individuals with TB receive combined treatment for both diseases, irrespective of CD4+ cell count. ART (Anti Retroviral Therapy) along with ATT (Anti Tuberculosis Treatment) is the only available treatment in present time. Though the timing of starting ART is the debatable question due to the risk of immune reconstitution inflammatory syndrome (IRIS). The advantages of early ART include reduction in early mortality, reduction in relapses, preventing drug resistance to ATT and reduction in occurrence of HIV-associated infections other than TB. The disadvantages include cumulative toxicity of ART and ATT, drug interactions leading to inflammatory reactions are the limiting factors for choosing the combination of ATT and ART.

A systematic review investigated the optimal timing of starting antiretroviral therapy in adults with newly diagnosed pulmonary tuberculosis. The review authors included eight trials, that were generally well-conducted, with over 4500 patients in total. The early provision of antiretroviral therapy in HIV-infected adults with newly diagnosed tuberculosis improved survival in patients who had a low CD4 count (less than 0.050 x 109 cells/L). However, such therapy doubled the risk for IRIS. Regarding patients with higher CD4 counts (more than 0.050 x 109 cells/L), the evidence is not sufficient to make a conclusion about benefits or risks of early antiretroviral therapy.

Testing for miliary tuberculosis is conducted in a similar manner as for other forms of tuberculosis, although a number of tests must be conducted on a patient to confirm diagnosis. Tests include chest x-ray, sputum culture, bronchoscopy, open lung biopsy, head CT/MRI, blood cultures, fundoscopy, and electrocardiography. The tuberculosis (TB) blood test, also called an Interferon Gamma Release Assay or IGRA, is a way to diagnose latent TB.

A variety of neurological complications have been noted in miliary tuberculosis patients—tuberculous meningitis and cerebral tuberculomas being the most frequent. However, a majority of patients improve following antituberculous treatment. Rarely lymphangitic spread of lung cancer could mimic miliary pattern of tuberculosis on regular chest X-ray.

The tuberculin skin test, commonly used for detection of other forms of tuberculosis, is not useful in the detection of miliary tuberculosis. The tuberculin skin test fails due to the high numbers of false negatives. These false negatives may occur because of higher rates of tuberculin anergy compared to other forms of tuberculosis.

Successful diagnosis of XDR-TB depends on the patient’s access to quality health-care services. If TB bacteria are found in the sputum, the diagnosis of TB can be made in a day or two, but this finding will not be able to distinguish between drug-susceptible and drug-resistant TB. To evaluate drug susceptibility, the bacteria need to be cultivated and tested in a suitable laboratory. Final diagnosis in this way for TB, and especially for XDR-TB, may take from 6 to 16 weeks. To reduce the time needed for diagnosis, new tools for rapid TB diagnosis are urgently needed.

The original method used to test for MDR-TB and XDR-TB was the Drug Susceptibility Testing (DST). DST is capable of determining how well four primary antitubercular drugs inhibit the growth of Mycobacterium Tuberculosis. The four primary antitubercular drugs are Isoniazid, Rifampin, Ethambutol and Pyrazinamide. Drug Susceptibility testing is done by making a Lowenstein-Jensen medium plate and spreading the bacteria on the plate. Disks containing one of the four primary drugs are added to the plate. After weeks of allowing the bacteria to grow the plate is checked for clear areas around the disk. If there is a clear area, the drug has killed the bacteria and most likely the bacteria is not resistant to that drug.

As "Mycobacterium tuberculosis" evolved new strains of resistant bacteria were being found such as XDR-TB. The problem was that primary DST was not suitable for testing bacteria strains that were extensively drug resistant. This problem was starting to be fixed when drug susceptibility tests started including not just the four primary drugs, but secondary drugs. This secondary test is known as Bactec MGIT 960 System. Although Bactec MGIT 960 System was accurate it was still slow at determining the level of resistance.

Diagnosis of MDR and XDR-TB in children is challenging. With an increasing number of cases being reported worldwide there is a great need for better diagnostic tools available for pediatric patients.

In recent years drug resistant tuberculosis testing has shown a lot of progress. Some studies have found an in-house assay that could rapidly detect resistance to drugs involved in the definition of XDR-TB directly from smear-positive specimens. The assay is called Reverse Line Blot Hybridization Assay also known as RLBH. The study showed that the results of RLBH were as accurate as other drug susceptibility tests, but at the same time didn`t take weeks to get results. RLBH testing only took 3 days to determine how resistant the strain of bacteria was.

The current research has shown progress in the testing of drug resistance. A recent study found that a research technique known as direct nitrate reductase assay (D-NRA) showed efficient accuracy for the rapid and simultaneous detection of resistance to isoniazid (INH), rifampicin (RIF), kanamycin (KAN) and ofloxacin (OFL). D-NRA results were obtained in 16.9 days, comparably less than other drug susceptibility testing. At the same time the study mentioned how D-NRA is a low-cost technology, easy to set up in clinical laboratories and suitable to be used for DST of M. tuberculosis in all smear-positive samples.

Biochemical tests used in the identification of infectious agents include the detection of metabolic or enzymatic products characteristic of a particular infectious agent. Since bacteria ferment carbohydrates in patterns characteristic of their genus and species, the detection of fermentation products is commonly used in bacterial identification. Acids, alcohols and gases are usually detected in these tests when bacteria are grown in selective liquid or solid media.

The isolation of enzymes from infected tissue can also provide the basis of a biochemical diagnosis of an infectious disease. For example, humans can make neither RNA replicases nor reverse transcriptase, and the presence of these enzymes are characteristic of specific types of viral infections. The ability of the viral protein hemagglutinin to bind red blood cells together into a detectable matrix may also be characterized as a biochemical test for viral infection, although strictly speaking hemagglutinin is not an "enzyme" and has no metabolic function.

Serological methods are highly sensitive, specific and often extremely rapid tests used to identify microorganisms. These tests are based upon the ability of an antibody to bind specifically to an antigen. The antigen, usually a protein or carbohydrate made by an infectious agent, is bound by the antibody. This binding then sets off a chain of events that can be visibly obvious in various ways, dependent upon the test. For example, "Strep throat" is often diagnosed within minutes, and is based on the appearance of antigens made by the causative agent, "S. pyogenes", that is retrieved from a patients throat with a cotton swab. Serological tests, if available, are usually the preferred route of identification, however the tests are costly to develop and the reagents used in the test often require refrigeration. Some serological methods are extremely costly, although when commonly used, such as with the "strep test", they can be inexpensive.

Complex serological techniques have been developed into what are known as Immunoassays. Immunoassays can use the basic antibody – antigen binding as the basis to produce an electro-magnetic or particle radiation signal, which can be detected by some form of instrumentation. Signal of unknowns can be compared to that of standards allowing quantitation of the target antigen. To aid in the diagnosis of infectious diseases, immunoassays can detect or measure antigens from either infectious agents or proteins generated by an infected organism in response to a foreign agent. For example, immunoassay A may detect the presence of a surface protein from a virus particle. Immunoassay B on the other hand may detect or measure antibodies produced by an organism's immune system that are made to neutralize and allow the destruction of the virus.

Instrumentation can be used to read extremely small signals created by secondary reactions linked to the antibody – antigen binding. Instrumentation can control sampling, reagent use, reaction times, signal detection, calculation of results, and data management to yield a cost effective automated process for diagnosis of infectious disease.

Given the wide range of bacteria, viruses, and other pathogens that cause debilitating and life-threatening illness, the ability to quickly identify the cause of infection is important yet often challenging. For example, more than half of cases of encephalitis, a severe illness affecting the brain, remain undiagnosed, despite extensive testing using state-of-the-art clinical laboratory methods. Metagenomics is currently being researched for clinical use, and shows promise as a sensitive and rapid way to diagnose infection using a single all-encompassing test. This test is similar to current PCR tests; however, amplification of genetic material is unbiased rather than using primers for a specific infectious agent. This amplification step is followed by next-generation sequencing and alignment comparisons using large databases of thousands of organismic and viral genomes.

Metagenomic sequencing could prove especially useful for diagnosis when the patient is immunocompromised. An ever-wider array of infectious agents can cause serious harm to individuals with immunosuppression, so clinical screening must often be broader. Additionally, the expression of symptoms is often atypical, making clinical diagnosis based on presentation more difficult. Thirdly, diagnostic methods that rely on the detection of antibodies are more likely to fail. A broad, sensitive test for pathogens that detects the presence of infectious material rather than antibodies is therefore highly desirable.

Countries aim to prevent XDR-TB by ensuring that the work of their national TB control programmes, and of all practitioners working with people with TB, is carried out according to the International Standards for TB Care. These emphasize providing proper diagnosis and treatment to all TB patients, including those with drug-resistant TB; assuring regular, timely supplies of all anti-TB drugs; proper management of anti-TB drugs and providing support to patients to maximize adherence to prescribed regimens; caring for XDR-TB cases in a centre with proper ventilation, and minimizing contact with other patients, particularly those with HIV, especially in the early stages before treatment has had a chance to reduce the infectiousness. Also an effective disease control infrastructure is necessary for the prevention of XDR tuberculosis. Increased funding for research, and strengthened laboratory facilities are much required. Immediate detection through drug susceptibility testing's are vital, when trying to stop the spread of XDR tuberculosis.

There are several methods to diagnose meningeal syphilis. One of the most common ways include visualizing the organisms by immunofluorescence and dark field microscopy. Dark field microscopy initially had the finding that the spirochete has a corkscrew appearance and that it is spirillar and gram (-) bacteria. Another method would also be through the screening test and serology. Serology includes two types of antibody test: Nontreponemal antibody test and Treponemal antibody test (specific test). The Nontreponemal antibody test screens with VDRL (Venereal Disease Research Lab) and RPR (Rapid Plasma Reagin). The Treponemal antibody test (specific test) confirms with FTA-ABS (Fluorescent treponemal antibody-absorption). Brain imaging and MRI scans may be used when diagnosing patients; however, they do not prove to be as effective as specific tests. Specific tests for treponemal antibody are typically more expensive because the earliest anitbodies bind to spirochetes. These tests are usually more specific and remain positive in patients with other treponemal diseases.

A diagnosis of latent tuberculosis (LTB), also called latent tuberculosis infection (LTBI) means a patient is infected with "Mycobacterium tuberculosis", but the patient does not have active tuberculosis. Active tuberculosis can be contagious while latent tuberculosis is not, and it is therefore not possible to get TB from someone with latent tuberculosis. The main risk is that approximately 10% of these patients (5% in the first two years after infection and 0.1% per year thereafter) will go on to develop active tuberculosis. This is particularly true, and there is added risk, in particular situations such as medication that suppresses the immune system or advancing age.

The identification and treatment of people with latent TB is an important part of controlling this disease. Various treatment regimens are in use to treat latent tuberculosis, which generally need to be taken for several months.

Diagnosis can be achieved through blood cultures, or cultures of other bodily fluids such as sputum. Bone marrow culture can often yield an earlier diagnosis, but is usually avoided as an initial diagnostic step because of its invasiveness.

Many people will have anemia and neutropenia if bone marrow is involved. MAC bacteria should always be considered in a person with HIV infection presenting with diarrhea.

The diagnosis requires consistent symptoms with two additional signs:

- Chest X-ray or CT scan showing evidence of right middle lobe (or left lingular lobe) lung infection

- Sputum culture or bronchoalveolar lavage culture demonstrating the infection is caused by MAC

Disseminated MAC is most readily diagnosed by one positive blood culture. Blood cultures should be performed in patients with symptoms, signs, or laboratory abnormalities compatible with mycobacterium infection. Blood cultures are not routinely recommended for asymptomatic persons, even for those who have CD4+ T-lymphocyte counts less than 100 cells/uL.

Dark ground microscopy of serous fluid from a chancre may be used to make an immediate diagnosis. Hospitals do not always have equipment or experienced staff members, and testing must be done within 10 minutes of acquiring the sample. Sensitivity has been reported to be nearly 80%; therefore the test can only be used to confirm a diagnosis, but not to rule one out. Two other tests can be carried out on a sample from the chancre: direct fluorescent antibody testing and nucleic acid amplification tests. Direct fluorescent testing uses antibodies tagged with fluorescein, which attach to specific syphilis proteins, while nucleic acid amplification uses techniques, such as the polymerase chain reaction, to detect the presence of specific syphilis genes. These tests are not as time-sensitive, as they do not require living bacteria to make the diagnosis.

Blood tests are divided into nontreponemal and treponemal tests.

Nontreponemal tests are used initially, and include venereal disease research laboratory (VDRL) and rapid plasma reagin (RPR) tests. False positives on the nontreponemal tests can occur with some viral infections, such as varicella (chickenpox) and measles. False positives can also occur with lymphoma, tuberculosis, malaria, endocarditis, connective tissue disease, and pregnancy.

Because of the possibility of false positives with nontreponemal tests, confirmation is required with a treponemal test, such as treponemal pallidum particle agglutination (TPHA) or fluorescent treponemal antibody absorption test (FTA-Abs). Treponemal antibody tests usually become positive two to five weeks after the initial infection. Neurosyphilis is diagnosed by finding high numbers of leukocytes (predominately lymphocytes) and high protein levels in the cerebrospinal fluid in the setting of a known syphilis infection.

If left untreated, miliary tuberculosis is almost always fatal. Although most cases of miliary tuberculosis are treatable, the mortality rate among children with miliary tuberculosis remains 15 to 20% and for adults 25 to 30%. One of the main causes for these high mortality rates includes late detection of disease caused by non-specific symptoms. Non-specific symptoms include: coughing, weight loss, or organ dysfunction. These symptoms may be implicated in numerous disorders, thus delaying diagnosis. Misdiagnosis with tuberculosis meningitis is also a common occurrence when patients are tested for tuberculosis, since the two forms of tuberculosis have high rates of co-occurrence.

"TB Bacteria Are Spread Only from a Person with Active TB Disease ... In people who develop active TB of the lungs, also called pulmonary TB, the TB skin test will often be positive. In addition, they will show all the signs and symptoms of TB disease, and can pass the bacteria to others. So, if a person with TB of the lungs sneezes, coughs, talks, sings, or does anything that forces the bacteria into the air, other people nearby may breathe in TB bacteria. Statistics show that approximately one-third of people exposed to pulmonary TB become infected with the bacteria, but only one in ten of these infected people develop active TB disease during their lifetimes."

However, exposure to tuberculosis is very unlikely to happen when one is exposed for a few minutes in a store or in a few minutes social contact. "It usually takes prolonged exposure to someone with active TB disease for someone to become infected.

After exposure, it usually takes 8 to 10 weeks before the TB test would show if someone had become infected." "Depending on ventilation and other factors, these tiny droplets [from the person who has active tuberculosis] can remain suspended in the air for several hours. Should another person inhale them, he or she may become infected with TB. The probability of transmission will be related to the infectiousness of the person with TB, the environment where the exposure occurred, the duration of the exposure, and the susceptibility of the host." In fact, "it isn't easy to catch TB. You need consistent exposure to the contagious person for a long time. For that reason, you're more likely to catch TB from a relative than a stranger."

If a person had latent tuberculosis, they do not have active/contagious tuberculosis. Once exposed, people very often have latent tuberculosis. To convert to active tuberculosis, the bacteria must become active.

People have medical privacy or "confidentiality" and do not have to reveal their active tuberculosis case to family, friends, or co-workers; therefore, the person who gets latent tuberculosis may never know who had the active case of tuberculosis that caused the latent tuberculosis diagnosis for them. Only by required testing (required in some jobs)

The most popular treatment forms for any type of syphilis uses penicillin, which has been an effective treatment used since the 1940s.

Other forms also include Benzathine penicillin, which is usually used for primary and secondary syphilis (it has no resistance to penicillin however). Benzathine penicillin is used for long acting form, and if conditions worsen, penicillin G is used for late syphilis.

There are several ways that drug resistance to TB, and drug resistance in general, can be prevented:

1. Rapid diagnosis & treatment of TB: One of the greatest risk factors for drug resistant TB is problems in treatment and diagnosis, especially in developing countries. If TB is identified and treated soon, drug resistance can be avoided.

2. Completion of treatment: Previous treatment of TB is an indicator of MDR TB. If the patient does not complete his/her antibiotic treatment, or if the physician does not prescribe the proper antibiotic regimen, resistance can develop. Also, drugs that are of poor quality or less in quantity, especially in developing countries, contribute to MDR TB.

3. Patients with HIV/AIDS should be identified and diagnosed as soon as possible. They lack the immunity to fight the TB infection and are at great risk of developing drug resistance.

4. Identify contacts who could have contracted TB: i.e. family members, people in close contact, etc.

5. Research: Much research and funding is needed in the diagnosis, prevention and treatment of TB and MDR TB.

"Opponents of a universal tuberculosis treatment, reasoning from misguided notions of cost-effectiveness, fail to acknowledge that MDRTB is not a disease of poor people in distant places. The disease is infectious and airborne. Treating only one group of patients looks inexpensive in the short run, but will prove disastrous for all in the long run."- Paul Farmer

MAC in patients with HIV disease is theorized to represent recent acquisition rather than latent infection reactivating (which is the case in many other opportunistic infections in immunocompromised patients).

The risk of MAC is inversely related to the patient's CD4 count, and increases significantly when the CD4 count decreases below 50 cells/mm³. Other risk factors for acquisition of MAC infection include using an indoor swimming pool, consumption of raw or partially cooked fish or shellfish, bronchoscopy and treatment with granulocyte stimulating factor.

Disseminated disease was previously the common presentation prior to the advent of highly active antiretroviral therapy (HAART). Today, in regions where HAART is the standard of care, localized disease presentation is more likely. This generally includes a focal lymphadenopathy/lymphadenitis.

Community-based treatment programs such as DOTS-Plus, a MDR-TB-specialized treatment using the popular Directly Observed Therapy – Short Course (DOTS) initiative, have shown considerable success in the of the world. In these locales, these programs have proven to be a good option for proper treatment of MDR-TB in poor, rural areas. A successful example has been in Lima, Peru, where the program has seen cure rates of over 80%.

However, TB clinicians have expressed concern in the DOTS program administered in the Republic of Georgia because it is anchored in a passive case finding. This means that the system depends on patients coming to health care providers, without conducting compulsory screenings. As medical anthropologists like Erin Koch have shown, this form of implementation does not suit all cultural structures. They urge that the DOTS protocol be constantly reformed in the context of local practices, forms of knowledge and everyday life.

Erin Koch has utilized Paul Farmer’s concept of “structural” violence as a perspective for understanding how “institutions, environment, poverty, and power reproduce, solidify, and naturalize the uneven distribution of disease and access to resources”. She has also studied the effectiveness of the DOTS protocol in the widespread disease of tuberculosis in the Georgian prison system. Unlike the DOTS passive case finding utilized for the general Georgian public, the multiple-level surveillance in the prison system has proven more successful in reducing the spread of tuberculosis while increasing rates of cure.

Koch critically notes that because the DOTS protocol aims to change the individual’s behavior without addressing the need to change the institutional, political, and economic contexts, certain limitations arise, such as MDR tuberculosis.

Paul Farmer believes that DOTS should be the cornerstone of tuberculosis control around the world.

Totally drug-resistant tuberculosis (TDR-TB) is a generic term for tuberculosis strains that are resistant to a wider range of drugs than strains classified as extensively drug-resistant tuberculosis. TDR-TB has been identified in three countries; India, Iran, and Italy. The emergence of TDR-TB has been documented in four major publications. However, it is not yet recognised by the World Health Organization.

TDR-TB has resulted from further mutations within the bacterial genome to confer resistance, beyond those seen in XDR- and MDR-TB. Development of resistance is associated with poor management of cases. Drug resistance testing occurs in only 9% of TB cases worldwide. Without testing to determine drug resistance profiles, MDR- or XDR-TB patients may develop resistance to additional drugs. TDR-TB is relatively poorly documented, as many countries do not test patient samples against a broad enough range of drugs to diagnose such a comprehensive array of resistance. The United Nations' Special Programme for Research and Training in Tropical Diseases has set up a TDR Tuberculosis Specimen Bank to archive specimens of TDR-TB.

The diagnosis is confirmed by a skin biopsy and a positive culture for acid-fast bacilli. A PPD test may also result positive.

This is a group of tests that use polymerase chain reaction (PCR) to detect mycobacterial nucleic acid. These test vary in which nucleic acid sequence they detect and vary in their accuracy. The two most common commercially available tests are the amplified mycobacterium tuberculosis direct test (MTD, Gen-Probe) and Amplicor. In 2007, review concluded that for diagnosing tuberculous meningitis "Individually, the AMTD test appears to perform the best (sensitivity 74% and specificity 98%)", they found the pooled prevalence of TB meningitis to be 29%.

Some ways to prevent airborne diseases include washing hands, using appropriate hand disinfection, getting regular immunizations against diseases believed to be locally present, wearing a respirator and limiting time spent in the presence of any patient likely to be a source of infection.

Exposure to a patient or animal with an airborne disease does not guarantee receiving the disease. Because of the changes in host immunity and how much the host was exposed to the particles in the air makes a difference to how the disease affects the body.

Antibiotics are not prescribed for patients to control viral infections. They may however be prescribed to a flu patient for instance, to control or prevent bacterial secondary infections. They also may be used in dealing with air-borne bacterial primary infections, such as pneumonic plague.

Additionally the Centers for Disease Control and Prevention (CDC) has told consumers about vaccination and following careful hygiene and sanitation protocols for airborne disease prevention. Consumers also have access to preventive measures like UV Air purification devices that FDA and EPA-certified laboratory test data has verified as effective in inactivating a broad array of airborne infectious diseases. Many public health specialists recommend social distancing to reduce the transmission of airborne infections.

Urogenital tuberculosis may cause strictures of the ureter, which, however, may heal when infection is treated.