Strep, short for Streptococcus, refers to a group of bacteria causing various infections. While “strep” often brings to mind “strep throat,” a common infection of the pharynx, some Streptococcus types can affect the lungs. However, the connection is not always direct, especially concerning common strep throat.
What is Streptococcus?
Streptococcus is a genus of spherical, Gram-positive bacteria that typically grow in chains. Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is the primary cause of “strep throat” and commonly resides in the nose and throat.
Infection with Streptococcus pyogenes spreads easily through respiratory droplets released when an infected individual coughs, sneezes, or talks. It can also be acquired by touching contaminated surfaces and then touching the mouth or nose.
Strep and Primary Lung Infections
Strep throat, caused by Streptococcus pyogenes, generally does not lead to primary lung infections like bronchitis or pneumonia. Its symptoms primarily affect the throat, presenting as soreness, scratchiness, and painful swallowing. Unlike many respiratory illnesses, strep throat usually does not involve a cough, nasal congestion, or shortness of breath.
Other Streptococcus species, however, are known causes of direct lung infections. For instance, Streptococcus pneumoniae is a leading cause of bacterial pneumonia. This highlights the distinction between the strep that causes throat infections and other streptococcal species that target the lungs directly.
How Strep Can Impact Lung Health Indirectly
While strep throat does not typically cause lung infections, untreated Streptococcus pyogenes infections can, in rare instances, lead to complications that indirectly affect lung health.
Rheumatic Fever
One complication is rheumatic fever, which can develop after an untreated strep throat infection. This can lead to rheumatic heart disease and heart failure, causing fluid to accumulate in the lungs (pulmonary edema), which impairs breathing.
Post-Streptococcal Glomerulonephritis (PSGN)
Another uncommon complication is post-streptococcal glomerulonephritis (PSGN), a kidney disorder. When kidney function is compromised, the body may retain excess fluid. This fluid can extend to the lungs, leading to respiratory distress.
Invasive Group A Strep (iGAS) Disease
A severe, yet rare, complication is invasive Group A Strep (iGAS) disease. This occurs when Streptococcus pyogenes invades normally sterile body parts, such as the bloodstream or organs. In such cases, the bacteria can directly cause pneumonia if they reach the lungs. iGAS can also lead to conditions like toxic shock syndrome, where widespread inflammation might contribute to severe lung injury, such as Acute Respiratory Distress Syndrome (ARDS).
Distinguishing Strep from Other Respiratory Illnesses
Differentiating strep throat from other respiratory illnesses is important for appropriate treatment. Symptoms like a persistent cough, nasal congestion, sneezing, and generalized body aches are more commonly associated with viral infections, such as the common cold, influenza, or viral bronchitis, which directly affect the respiratory system.
In contrast, strep throat’s primary symptoms are typically confined to the throat. These include a sore throat that often appears suddenly, sometimes accompanied by fever, pain when swallowing, and swollen neck lymph nodes. The absence of significant respiratory symptoms like coughing and sneezing often helps distinguish strep throat from viral respiratory infections.