Final answer:
In a patient with pyelonephritis, a 'shift to the left' indicates an increased presence of neutrophils fighting the infection, reflected in the blood and urine. Neutrophils play a crucial role in the innate immune response by phagocytosing pathogens and are thus a key marker in diagnosing this kidney infection, which is treated with antibiotics.
Step-by-step explanation:
The WBC shift to the left in a patient with pyelonephritis indicates that neutrophils are being recruited to fight the infection. This kind of shift usually entails an increase in the young forms of white blood cells in the bloodstream and is commonly seen in bacterial infections where neutrophils are activated due to their phagocytic nature, producing inflammatory cytokines for pathogen destruction.
Neutrophils contain granules filled with enzymes such as lysozyme and oxidants like hydrogen peroxide to break down bacterial cell walls. High neutrophil counts are an indication of infection or inflammation, and their presence in the urine, a condition known as pyuria, is an important diagnostic marker for pyelonephritis. The presence of pus, a more macroscopic sign of infection, is due to the accumulation of dead pathogens, neutrophils, and tissue fluids at the infection site.
When diagnosing pyelonephritis, physicians utilize urine tests, including microscopy, culture, and the detection of leukocyte esterase and nitrite levels, blood tests for evaluating pathogen spread, and sometimes imaging of the kidneys to help diagnose and assess the infection. Treatment typically includes a course of antibiotics.