Klebsiella pneumoniae pathogenesis

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University of Oklahoma Study Abroad Microbiology in Arezzo, Italy(The caption below the image)[1]

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Scanning electron microscope image of Clostridium difficile. From: Bioquell.com [2]

Etiology/Bacteriology

Taxonomy

| Domain = Bacteria

| Phylum = Proteobacteria

| Class = Gammaproteobacteria

| Order = Enterobacteriales

| Family = Enterobacteriaceae

| Genus = Klebsiella

| Species = K. pneumoniae [1]

NCBI: Taxonomy

Species

Klebsiella pneumoniae

NCBI: Complete genome here

History

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Pathogenesis

Transmission

Klebsiella infections is spread through exposure to the bacteria via respiratory tract, which causes pneumonia, or the blood to cause an infection in the bloostream. Klebsiella infections are most well-known in hospitals spread through person-to-person contact by contaminated hands of surrounded people in the hospitals, whether it be an employee or a patient. Klebsiella is spread very easily and rapidly, but not through the air. Healthcare settings are most vulnerable to Klebsiella infections due to the nature of procedures that allow easy access of bacteria into the body. Patients who are on ventilators, catheters, or surgery wounds are highly prone to catching this deadly infection. (CDC)

Incubation/Infectious Dose/Colonization

In humans, the infectious dose is not known. As for the incubation period, it is also not fully understood but possibly arises within a number of days. (BU) Klebsiella bacteria are found widely through nature in soil and water. In regards to human, K. pneumoniae is prevalent in normal microbiota of the intestinal tract and colon, but not in alarmingly high numbers. They may also be found in the mouth and the skin. (Lousiana) Infection of K. pneumonia occur in the lungs, where they cause necrosis, inflammation, and hemorrhage within the lung tissue (medscape). This is caused by aspirating oropharyngeal microorganisms into the lower respiratory tract. Hospital-acquired infections rely on the urinary tract, lower respirator tract, biliary tract, and surgical wounds to set up colonization. (medscape)

Epidemiology

When dealing with hospital-acquired bacterial infections caused by K. pneumoniae can arise in different parts of the body and in different forms of illness depending on transmission. K. pneumoniae is responsible for 6-17% of UTI’s, 7-14% of pneumonia, 4-15% of septicemia, 2-4% of wound infections, 4-17 nosocomial infections in intensive care units, and 3-20% of all neonatal septicemia cases. All of these cases rank within at least the top 11 in comparison to all other bacterial pathogens. In the United States, people who suffer from alcoholism make up 66% of people affected by community-acquired pneumonia. K. pneumoniae is now among the top 8 pathogens in hospitals and is a rising issue among hospitals all around the world due to antibiotc resistance. In humans, K. pneumoniae resides in the nasopharynx and in the intestinal tract. Since gram-negative bacteria do not have good growth on human skin, they are rarely found there in comparison to internal parts of the body. Reported carrier rates are quire the opposite of this fact, when in a hospital environment. Carriers rated in hospitalized patients were 19% in the pharynx, 77% in the stool, and 42% on the hands. Even hospital employees had elevated rates of carriage to K. pneumoniae. These findings were linked to the over usage of broad-spectrum antibiotics rather than delivery of care. (NCBI) In 2011, an investivation of Klebsiella pneumonia carbapenemase (KPC)-producing Enterobacteriaceae was conducted in hospitals among patient with short and long-term stays. Over a 1-year period, KPC-producing Enterobacteriaceae was found throughout 4 counties in Indiana and Illinois. The source of the problem was found to be within long-term facilities and patients. (medscape) KPC has been found in a total of 44 states thus far. (PBS)

14% of bacteremia cases are because by K. pneumoniae, which places it in second place next to Escherichia coli for origins of gram-negative sepsis. Outbreaks of neonatal septicemia and K. pneumoniae can be found worldwide. In Israel, a number of hospital facilities reported increases in KPC-producing Enterobacteriaceae beginning in 2006, while the first case in the United States was reported in 2001. (oxford journals)

KPC Outbreak at NIH

In 2011, Klebsiella pnuemomiae Carbapenamase arrived in one of the most established and renowned hospitals, the Clinical Center at the National Institutes of Health in Bethesda, Maryland, known as the NIH. A 43-year-old woman was transferred to the NIH, who had lung transplant complications and a KPC infection. With no known, outbreak, NIH employee were relieved after clearing the infection and discharging the patient. Weeks later, a new patients tested positive for KPC, but with no know link to patient number one. Over the next six months, several patients were showing up positive for KPC and eventually quarantined from the rest of the hospital. Doctors began administering combination antibiotics, older formulas from decades back, and even experimental antibiotics. None of these methods seemed to work and ultimately, a total of 18 patients became infected with KPC. 6 patients died from KPC and the outbreak came to a halt just as fast as it started. Genetic analysis was used to understand the transmission sequence, The bacteria is thought to be home grown in that we have K. pneumoniae living in our digestive systems with a gene that can spread resistance to different bacteria. Today, the NIH knows that KPC is still lurking in the hospital. They only know that they must be extremely vigilant in the future due to the increasing rise of KPC infections in the United States. (PBS)===Virulence Factors===

References

Created by Victoria Ann Kappel Student of Dr. Tyrrell Conway, University of Oklahoma