When dealing with L. pneumophila serogroup 1, the urine antigen test is useful for early detection of Legionnaires disease and initiation of treatment, and has been helpful in early detection of outbreaks. However, it does not identify the specific subtypes, so it cannot be used to match the person with the environmental source of infection. The Legionella bacteria can be cultured from sputum or other respiratory samples. Legionella spp. stain poorly with Gram stain, stain positive with silver, and are cultured on charcoal yeast extract with iron and cysteine (CYE agar). A significant under-reporting problem occurs with legionellosis. Even in countries with effective health services and readily available diagnostic testing, about 90% of cases of Legionnaires disease are missed. This is partly due to the disease being a relatively rare form of pneumonia, which many clinicians may not have encountered before, thus may misdiagnose. A further issue is that people with legionellosis can present with a wide range of symptoms, some of which (such as diarrhea) may distract clinicians from making a correct diagnosis. Prevention
Although the risk of Legionnaires disease being spread by large-scale water systems cannot be eliminated, it can be greatly reduced by writing and enforcing a highly detailed, systematic water safety plan appropriate for the specific  facility involved (office building, hospital, hotel, spa, cruise ship, etc.) Some of the elements that such a plan may include are:

Keep water temperature either above or below the 20–50 °C (68–122 °F) range in which the Legionella bacterium thrives.
PID or Pid may refer to:

Medicine
Pelvic inflammatory disease or pelvic inflammatory disorder, an infection of the upper part of the female reproductive system
Primary immune deficiency, disorders in which part of the bodys immune system is missing or does not function properly
Prolapsed intervertebral disc, commonly called a herniated disc

Science, technology and engineering
BBC Programme Identifier, a unique identifier for a BBC television or radio programme brand, a season or series, or an individual episode
OBD-II PIDs (on-board diagnostics parameter IDs), requests for data through an OBD connector in automotive repair
Packet Identifier, a field in a MPEG transport stream packet
Passive infrared detector, a passive infrared sensor
Persistent identifier, a long-lasting reference to a document, file, web page, or other object
Phosphotyrosine-interacting domain, also known as phosphotyrosine-binding domain, a protein domain which bind to phosphotyrosine
Photoionization detector, measures volatile organic compounds and other gases
Physical Interface Device, a class of a USB device
PID controller (proportional-integral-derivative controller), a control concept used in automation
Piping and instrumentation diagram (P&ID), a diagram in the process industry which shows the piping of the process flow etc.