Learn about Klebsiella pneumoniae infection, its resistance mechanisms, pathogenesis, epidemiology, and preventive measures to combat this emerging health threat.
Klebsiella pneumoniae infection is a Gram-negative rod-shaped bacterium commonly found in the human gastrointestinal tract. Also known as Friedländer’s bacillus, this bacterium has caused diseases in humans since the late 19th century.
In recent years, treatment of Klebsiella pneumoniae infections has become increasingly challenging due to the rise of antibiotic resistance. While it usually poses no risk to healthy individuals, it can lead to severe illnesses, particularly in those with a high risk of infection, such as pneumonia, urinary tract infections, and stomach infections.
The presence of multidrug-resistant strains complicates treatment; these strains are resistant to antibiotics, including carbapenems, creating significant management challenges. Bacteria typically enter the body through person-to-person contact or via contaminated hospital equipment and supplies. Respiratory transmission is also a common cause of pneumonia associated with these infections.
Resistant Strains
Klebsiella pneumoniae is notorious for its resistance to multiple antibiotics, making infections difficult to treat. The bacterium develops resistance through several mechanisms, including the production of extended-spectrum beta-lactamases (ESBL), carbapenem-resistant Klebsiella pneumoniae (CRKP), and multidrug-resistant Klebsiella pneumoniae (MDR-KP) strains. The last two pose a severe threat as effective treatment options are limited, and the risk of infection is notably higher in medical facilities.
Antimicrobial Resistance Gene Transfer
Klebsiella pneumoniae is capable of acquiring and transferring antimicrobial resistance genes to other bacteria, primarily through plasmids, but also via transposons and integrons. Plasmids are circular DNA sequences containing genes that confer resistance to antibiotics. This gene transfer enhances the ability of different Klebsiella pneumoniae strains to infect both their own and other organisms’ immune systems, complicating treatment further. Effective antimicrobial stewardship and robust infection control measures are essential for preventing many infectious diseases.
Pathogenesis
Klebsiella pneumoniae causes respiratory and intestinal infections by using adhesins to attach to host cells. The bacterium infiltrates tissues aided by its capsules, polysaccharides, and pili. Capsule polysaccharides promote colonization by enabling the bacteria to evade phagocytosis by the immune system.
Klebsiella pneumoniae produces various toxins and enzymes that cause tissue damage at the infection site. As part of the inflammatory response, various immune cells are recruited, cytokines are released, and additional pathways are activated. While these mechanisms generally aid in eliminating the infection, they can also lead to further tissue damage and systemic effects. In severe cases, Klebsiella pneumoniae may infect other organs, leading to significant changes within the body.
Overall, Klebsiella pneumoniae infections reflect a balance between the bacterium’s virulence factors and the host’s immune resistance, resulting in tissue invasion and damage.
Epidemiology
In the United States, Klebsiella pneumoniae infections are more prevalent in middle-aged and older men than in women, particularly those with severe underlying conditions. Patients with weakened immune systems—due to factors such as diabetes, alcoholism, cancer, liver disease, pulmonary obstructive disease, glucocorticoid therapy, or kidney failure—are at greater risk. Humans are the primary reservoir for Klebsiella pneumoniae, with the main sources of infection being the intestines of patients and the hands of hospital personnel, leading to nosocomial infections.
Among hospitalized patients, the burden of Klebsiella pneumoniae in the oral cavity and skin is four times higher than in the general population. Klebsiella pneumoniae accounts for approximately 11.8% of hospital-acquired pneumonia worldwide and causes between 8% to 12% of all infections, occurring in only 7% of non-ventilated patients.
Transmission
Klebsiella pneumoniae spreads through person-to-person contact, contaminated equipment, or community settings, with hospitals and nursing homes being common environments for infection, especially among immunocompromised individuals. Inadequate care of medical equipment, such as respirators and tubes, can contribute to the spread of these infections.
Signs and Symptoms
Symptoms of Klebsiella pneumoniae infection vary based on the location and severity of the disease. In some cases, there may be no noticeable symptoms, making it a silent threat. When symptoms do manifest, they can include pneumonia, urinary tract infections, skin or soft tissue infections, liver abscesses, blood infections, ulcers, meningitis, or endophthalmitis. Individuals with weakened immune systems or those undergoing treatment are more susceptible to severe symptoms.
Risk Factors
Risk factors for Klebsiella pneumoniae infection include prolonged use of antibiotics, corticosteroids, or both, hospitalization, mechanical ventilation, bowel or urinary incontinence, and immunocompromised states such as cancer treatment and organ transplantation.
Diagnosis
Diagnosis of Klebsiella pneumoniae infections involves various tests based on presenting symptoms. Physicians conduct physical examinations to check for signs of pain and other indicators. Fluids, including blood, sputum, urine, and cerebrospinal fluid, are tested for the presence of bacteria. Imaging tests such as chest X-rays, PET scans, ultrasounds, or CT scans may be utilized to evaluate the lungs for pneumonia or liver disease. Additionally, breathing apparatuses and catheters can be tested for Klebsiella pneumoniae contamination.
Prevention Measures
To prevent the spread of Klebsiella pneumoniae infections, good hand hygiene is crucial. Regular handwashing is essential before touching the face, before and after food preparation, after using the restroom, and following coughs or sneezes. Healthcare workers should wear gloves and protective clothing and frequently disinfect their hands and equipment when treating patients with Klebsiella infections.
This article is jointly written by Palwasha Chandni and Muhammad Hamza from University of Veterinary and Animal Sciences Lahore, Sub Campus Jhang