Diabetes is associated with a high incidence of infections, with respiratory infections being the most common, followed by urinary tract infections and skin infections. Infections can further aggravate the pre-existing metabolic disorders in diabetic patients, and the two interact with each other as cause and effect.
Section I. Main mechanisms of complications of diabetes mellitus infection
Due to metabolic disorders, diabetic patients often have a low functioning immune system, which is the central link leading to infection in the organism. It is mainly manifested in the following aspects.
I. Hyperglycemia
Hyperglycemia can increase plasma osmolality, disrupt intra-leukocyte glucose metabolism and reduce glycolytic capacity, leading to a decrease in neutrophil chemotaxis, phagocytosis and bactericidal capacity. In addition, long-term hyperglycemia is conducive to the growth and reproduction of pathogenic microorganisms, especially in the respiratory tract, urinary tract, skin and female vulva, often causing infections of pathogenic microorganisms such as streptococcus, Escherichia coli, pneumococcus and Candida.
Second, metabolic disorders
In diabetes mellitus, the metabolism in the body is disturbed, protein decomposition is accelerated, synthesis is slowed down, immunoglobulin and complement production are weakened, and the conversion rate of lymphocytes is reduced, resulting in a weakened cellular and humoral immune response.
III. Insulin deficiency
Insulin receptors exist on the immune cells of the body, and insulin can promote the function of B cells and T cells in vivo and in vitro to enhance the antigen presentation.
IV. Vascular lesions
Diabetic patients are prone to vasculopathy, which causes abnormalities in the structure and function of large, medium and microvessels, resulting in slow blood flow and impaired blood circulation, thus affecting the timely local clearance of pathogenic bacteria.
V. Peripheral neuropathy and autonomic neuropathy
Peripheral neuropathy is manifested by abnormal sensory loss in the extremities, which is often not easily detected at an early stage once the injury is suffered (ulceration, contusion, scalding) and is prone to infection; while autonomic neuropathy is often accompanied by neurogenic bladder and bladder muscle weakness, which can lead to urinary retention and often requires the insertion of a urinary catheter, providing conditions for the invasion, colonization and reproduction of pathogenic microorganisms.
Sixth, the integrity of the skin is impaired
Due to the widespread presence of diabetic peripheral neuropathy and vasculopathy, thus making the skin vulnerable to breakage, it becomes a gateway to pathogenic microorganisms.
Section II. Infections in various systems
Diabetic secondary infections are mostly caused by septic bacteria, Mycobacterium tuberculosis, fungi, viruses, etc. The incidence is about 32.7%~90.3%, and can occur in most organs and systems throughout the body.
I. Respiratory system
The respiratory system is the main site of co-infection in diabetes, accounting for about 45%, and the morbidity and mortality rate can be as high as 41%. The lungs are the most common organ for respiratory infections, and pneumonia is the most common complication of diabetic complications of respiratory infections. E. coli, Streptococcus pneumoniae, and Staphylococcus are the common causative agents of pulmonary infections in diabetic patients. In addition, Pseudomonas aeruginosa, Enterobacter cloacae, and Klebsiella pneumoniae infections are also seen. When diabetes mellitus is combined with pulmonary infection, the onset is often rapid, the infection is not easily controlled, and a septic focal point is easily formed, such as a septic chest; although the patient’s body temperature is elevated at this time, it often does not reach the temperature level of septic infection in non-diabetic patients, and the systemic inflammatory response is not as strong as the latter. The clinical manifestations are often newly appeared fever, cough, coughing sputum, or aggravation of the symptoms of the original respiratory disease and the appearance of purulent sputum, the lungs may have wet rales or buckling and other signs, easy to complicate the cardiac and renal impairment, malnutrition, water and electrolyte disorders, acute metabolic disorders such as ketoacidosis, hyperosmolar coma, etc. in severe cases. Leukocyte count may be increased, and chest radiograph shows new lamellar and patchy pulmonary infiltrates.
This is followed by pulmonary tuberculosis, which is about 2-8 times more common in non-diabetic patients. It is most commonly seen in adolescents with poor glycemic control, the elderly, and the wasted. The clinical manifestations are often atypical and not easily detected. Most patients do not have symptoms of tuberculosis toxicity such as fever, hemoptysis, night sweats and coughing, but only symptoms of diabetes mellitus such as wasting and weakness. Unlike non-diabetic patients, TB lesions in diabetic patients are mostly located in the middle and lower lung fields, and the disease progresses rapidly, mainly in the form of caseous lesions, followed by exudative lesions and easy to form cavities. The rate of positive sputum for Mycobacterium tuberculosis is higher. Therefore, sputum should be routinely examined for Mycobacterium tuberculosis and tuberculin test in diabetic patients presenting with infiltrative lung shadow to avoid missed diagnosis. Bronchial and pulmonary lymphatic tuberculosis occur more often in children with diabetes.
In recent years, diabetes mellitus combined with pulmonary fungal infections has been increasing, and the rapid progress and high mortality rate have received more and more attention, which requires vigilance and differentiation. The common causative organisms are Candida albicans, Aspergillus, etc., while Coccidioides is an important causative organism of fungal pneumonia in patients with diabetic ketoacidosis.
Second, the urinary system
Urinary tract infections are second only to pulmonary infections, more in women than in men, 19% in the former and 2% in the latter, which is related to the short urethra in women. These include urethritis, cystitis, prostatitis and pyelonephritis, with cystitis and pyelonephritis being the most common. The common causative organisms are mostly Escherichia coli, accounting for about 50-70% of cases, mainly because of the high content of sugar in the urine of diabetic patients, and glucose is the main nutrient for gram-negative bacilli. In addition, Staphylococcus, Klebsiella pneumoniae, Enterococcus faecalis, etc. are seen. In recent years, with the wide application of broad-spectrum antibiotics, the detection rate of mycobacteria is higher, mostly Candida albicans infections, followed by Cryptococcus, smooth spherical mimic yeast and Trichoderma, etc. The clinical manifestations of diabetic complications of urinary tract infections are often atypical, and the infection is not easily controlled, and if not treated promptly, it can often develop into sepsis. If renal papillary necrosis occurs, it often leads to renal function impairment and high morbidity and mortality. Therefore, those who have clinical symptoms of urinary frequency, urinary urgency, or even fever and lumbago should undergo detailed examination including urinary routine, mid-stage urine culture, blood culture and ultrasound of the urinary tract.
Third, the skin mucous membrane soft tissue
Due to the microangiopathy and neuropathy of diabetes, it is easy to cause skin and mucous membrane damage, and cause infections that do not heal easily. In diabetic patients, boils are often recurrent and persistent, and the pathogenic bacteria are mostly Staphylococcus aureus infections. The next most common pathogens are necrotizing cellulitis and include hemolytic cocci, Staphylococcus aureus, and Clostridium perfringens. The onset and progression of the disease is violent, the inflammation is not easily confined, there is no wall, it is easy to spread around, and there is no obvious demarcation with normal tissue. In addition, the infection can also involve subcutaneous tissue and fascia to form necrotizing fasciitis, often caused by Streptococcus haemolyticus, anaerobic bacteria and Escherichia coli, and mostly occurs after trauma.
Diabetes mellitus combined with gangrene is a common and serious complication. It often starts as a purulent infection and can develop into purulent gangrenous necrosis if not treated properly, easily changing from dry gangrene to wet gangrene, which can lead to life-threatening sepsis and a mortality rate of more than 16%.
In addition, fungal infections of the skin, including dermatophytosis and cutaneous mucosal Candida, such as vulvodynia, glansitis, nail infection, perineal itching, vaginitis and orchitis, are also seen.
Fourth, other systemic infections
In addition, oral cavity, ear, nose and throat, can be co-infected, such as gingivitis, periodontitis, etc.; rhinitis, sinusitis; even seen in surgical diseases, such as cholecystitis, appendicitis, hepatobiliary system biliary system infection, and postoperative infection, sepsis, etc.
Section III. Treatment of diabetic co-infections
Diabetic co-infections should be detected and treated promptly, and even minor infections should not be ignored. The control of diabetic co-infection should be based on the diabetic condition, the location and severity of the infection, and the type of pathogenic microorganisms, so that a personalized treatment plan can be formulated and adjusted in a timely manner according to the therapeutic effect.
I. Strict control of high blood sugar
The first and foremost treatment of diabetic co-infection is to lower blood glucose, and controlling blood glucose at the ideal level is the key to treatment. Because hyperglycemia is not only an important cause of various complications, but also an important factor in the reduction of immune function. When the body is in a state of stress, glucocorticoid, growth hormone, glucagon and other hyperglycemic factors in the blood increase, which in turn increases blood sugar and makes the infection more difficult to control. For more serious infections, oral hypoglycemic drugs should be stopped in time and replaced by multiple subcutaneous injections of insulin, and when available, insulin pumps can be used for continuous subcutaneous infusion. When blood glucose is high (greater than 11.9 mmol/l), insulin can also be administered intravenously first. If there is no special contraindication, consider adding thiazolidinedione insulin sensitizer to enhance the efficacy of insulin.
Second, choose appropriate antibiotics to effectively control the infection
Once the infection is identified, smear examination of sputum, urine, blood and pus, culture and drug sensitivity test should be done as early as possible. Choose the best antibiotic treatment. Antibiotic treatment can be combined mainly with adequate amount and full course.
1, lung infection: drug sensitivity before the drug is often empirical drug, taking into account the positive cocci and negative bacilli. Such as Streptococcus pneumoniae, Staphylococcus aureus, etc.. Penicillin G, cefazolin sodium, cefmetazole, combined with an aminoglycoside such as butamycarbital or nethimycin sulfate; second or third generation cephalosporins, such as cefazoxime or ceftriaxone, can also be used. Allergy to penicillin can be replaced with erythromycin or azithromycin. In case of MRSA, vancomycin should be used instead. If it is Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and other negative mycobacterial infections, consider using oxypiperazine penicillin, cefotaxime or enzyme inhibitors such as Shupshen, etc.; if it is Candida albicans infection, use fluconazole, while Aspergillus infection is preferred to type II, B.
2, branched urine disease combined with tuberculosis: once the diagnosis is established, insulin should be used to control blood sugar, which can avoid the damage of oral hypoglycemic drugs to the liver, fasting blood sugar can be allowed to be slightly higher than normal or normal [8.33mmol/L (150mg/dl)]. The principles of chemotherapy for diabetes mellitus combined with pulmonary tuberculosis are the same as those for pulmonary tuberculosis alone, but the course of treatment should be extended appropriately, and the total course of treatment can be up to 2 years. Rifampin, isoniazid, pyrazinamide, aminoglutethimide or streptomycin can be used in combination. In severe cases, isoniazid can be administered intravenously, and we should be alert to the toxic side effects of anti-TB drugs and pay attention to impaired liver and kidney function.
3, urinary tract infections: general urinary tract infections can be used inexpensive booster joint sulfonate tablets (cosme) and sodium bicarbonate or oxypiperazine penicillin. Quinolines such as ciprofloxacin and levofloxacin can also be used. With the widespread use of antibiotics, there is now an increasing number of resistant bacterial beads. Cephalosporins such as ceftriaxone and cefotaxime can be used, and if necessary, B-lactamase inhibitors such as clavulanic acid and tazobactam can be added. It is best to give the drug intravenously, and when the body temperature drops to normal, the general condition can be changed to oral 3 days after improvement.
4. Penicillin G, cefazolin sodium or cefmetazole are often preferred for skin and mucous membrane infections; allergy to penicillin can be replaced with azithromycin or erythromycin; lower extremity infections ulcers are often a mixture of Gram-pressure stained positive and Gram-negative bacteria, fourth generation quinolines such as moxifloxacin or curvifloxacin can be used, while surgical local management should be strengthened.
For superficial fungal infections such as dermatophytosis, clotrimazole, miconazole, and ketoconazole can be used orally or applied locally.
Third, improve the nutritional status of the body
Diabetic patients have metabolic disorders of three major nutrients: sugar, protein, and fat, especially protein synthesis is reduced and catabolism is enhanced, making them prone to hypoproteinemia, which is one of the risk factors that predispose diabetic patients to and aggravate infections. Therefore, during the treatment of infection, diet and weight loss should not be excessively restrained. Adequate intake of protein, vitamins and inorganic salts should be supplemented with trace elements. It is best to use enteral nutrition when performing nutritional support, so that putting can avoid the large fluctuation of blood sugar and easy to pick up measurement, and also can avoid various complications of parenteral nutrition. In addition, attention should be paid to bed rest and suspension of conventional exercise therapy.
Fourth, strengthen care, closely observe the changes of vital signs, pay attention to maintaining water and electrolyte balance, and protect the function of important organs.
Because diabetic patients often have different degrees of decline in the function of each major organ, making the metabolic pressure caused by the infection more compensatory ability to decline, prone to complications of functional failure. For example, in case of complications of renal failure, the body’s ability to regulate water and electrolyte acid-base balance decreases, making it easy to complicate ketoacidosis or hyperosmolar coma; diabetes mellitus is mostly in elderly patients, and pulmonary infections are mostly severe infections, making it easy to complicate respiratory failure and sequential organ failure, so timely treatment with oxygen and even mechanical ventilation should be given.
V. In addition, it is necessary to educate diabetic patients to develop good hygiene habits, actively control the metabolic disorders of diabetes, enhance the body’s resistance, protect the local damage, reduce the occurrence of infection, and prophylactically inject influenza vaccine during the influenza epidemic season.
Section IV. Prognosis
Infection is one of the most serious complications of diabetes mellitus. Before there was insulin and antibiotics, infection was an important cause of death in diabetic patients. With the introduction of antibiotics and wide and reasonable clinical application, the prognosis of diabetic patients has been greatly improved, nevertheless, infection is still one of the important causes of death in diabetic patients, therefore, it should be given sufficient attention.