What to know about Klebsiella pneumoniae

Causes

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There are many types of K. pneumoniae bacteria. Some have capsules surrounding their cells, and others do not.

Researchers have currently identified 77 capsular types. Klebsiella bacteria without capsules are less infectious than those with capsules.

Humans are the primary carriers of K. pneumoniae in the environment, but most people will not develop an infection. People with weakened immune systems, due to medications or medical conditions, have a higher risk.

Researchers report that some populations carry more of this type of bacteria, including people of Chinese ethnicity and people with alcohol use disorder.

In some populations, the disease is more likely to cause certain infections. K. pneumoniae are the most common cause of hospital-acquired pneumonia in the United States, for example.

Meanwhile, in Western regions, Klebsiella rarely causes meningitis. However, in Taiwan, K. pneumoniae infection is a leading cause, responsible for about 25–40% of bacterial meningitis cases in adults.

Some people develop K. pneumoniae meningitis from liver abscesses. The bacteria from the abscess can travel from the liver to the central nervous system.

In addition, catheters and tools in medical procedures can transmit K. pneumoniae into the urinary tract, the bloodstream, and wounds.

Symptoms

Different types of infection with K. pneumoniae can cause different symptoms, which may resemble those of other bacterial infections.

If a doctor notices that a bacterial infection persists after the initial treatment, they may order tests to identify the specific bacteria responsible. The results help them choose the most appropriate antibiotic treatment.

Anyone who suspects that they have a urinary tract infection, pneumonia, meningitis, or cellulitis — all of which can result from K. pneumoniae — should consult a doctor right away.

The table below lists common symptoms of these conditions.

Treatment

Doctors treat K. pneumoniae infections with antibiotics. When an infection is hospital-associated, doctors use a class of antibiotics called carbapenems until results of sensitivity testing are available.

If a doctor suspects that the bacteria have developed antibiotic resistance, they can order tests to determine how sensitive the bacteria are to specific antibiotics, before selecting the most effective option.

It may be challenging for doctors to treat K. pneumoniae infections because increasingly fewer antibiotics are effective. Most recently, for example, some K. pneumoniae have developed resistance to carbapenems.

A doctor may prescribe a combination of antibiotics. One study observed lower mortality rates in people with bacteremia from K. pneumoniae who had received a combination of the antibiotics colistin, meropenem, and tigecycline.

When a person develops pneumonia from K. pneumoniae, doctors typically recommend a 2-week treatment with third- or fourth-generation cephalosporin, a fluoroquinolone, or one of these antibiotics in combination with an aminoglycoside.

People who are allergic to penicillin require a course of aztreonam or a quinolone.

Diagnosis

Doctors usually diagnose Klebsiella infections by examining either a sample of infected tissue or a sample of:

• sputum
• urine
• blood

Sometimes doctors order medical imaging tests, including:

• ultrasounds
• X-rays
• CT scans

Once the doctor confirms the diagnosis, they may run sensitivity tests to determine which antibiotic will most effectively treat the infection.

When to see a doctor

Anyone who suspects that they have a K. pneumoniae infection should seek medical attention right away.

If any infection persists after home care or an initial course of antibiotics, it is important to seek medical attention. The doctor may ask for additional testing to check the susceptibility of the bacteria to antibiotics.

Is it contagious?

K. pneumoniae infection is contagious. A person must come into contact with the bacteria, which do not spread through the air.

In hospitals, K. pneumoniae can spread through person-to-person contact. People may also come into contact with the bacteria through environmental exposure, though this occurs less often.

An individual may come into contact with this type of bacteria through:

• ventilators, or breathing machines
• intravenous catheters
• urinary catheters
• open wounds

Healthy family members of people with K. pneumoniae infections have a low risk of acquiring the infection.

However, taking every hygiene precaution is essential. Hand hygiene remains the best defense against K. pneumoniae infection.

Prognosis

When doctors identify K. pneumoniae in samples quickly and prescribe the appropriate antibiotics right away, the prognosis improves. However, delays in diagnosis and testing are common, and this can lead to a less favorable prognosis.

The prognosis for people with pneumonia from K. pneumoniae is often poor. Even when doctors choose the appropriate antibiotic therapy, mortality rates are 30–50%.

People with other diseases, such as diabetes, older adults, and people with compromised immune systems have the highest risks of mortality.

In people with pneumonia from these bacteria, the infection may impede lung function in the long term, possibly for months.

Summary

K. pneumoniae infections typically develop in hospital settings. People with weakened immune systems and chronic conditions have the highest risk.

K. pneumoniae have developed resistance to many antibiotics, and doctors may find it challenging to treat K. pneumoniae infections. However, testing the sensitivity of the bacteria in blood or tissue samples can help them identify the most effective course of treatment.

People with K. pneumoniae infections may transmit the bacteria to others. Taking every hygiene precaution, especially hand washing, is the best way to prevent K. pneumoniae infections from spreading.