Infections in immunocompromised patients

Immunocompromised patients have damaged natural defense mechanisms. In this case, infections are often caused by low virulence pathogens (opportunistic microorganisms). Infections with virulent microorganisms have a more severe course and tendency to chronicity and persistence. By immunosuppression we mean a condition in which the immune system is weakened iatrogenically, for example by the use of corticosteroids. The absence or alteration of the immune response modifies the clinical picture of the disease, which then does not have a typical course. Even severe infections can occur without fever, which obscures the true severity of the condition. In patients with immunodeficiency, early diagnosis and immediate initiation of appropriate treatment is very important, as infections can be fatal at more advanced stages. Infection (plus recurrence) is usually the first manifestation of immunodeficiency.

Period of natural immunocompromitation
 * 1) age over 65;
 * 2) narrower newborn age (ie the first week after birth);
 * 3) the last trimester of pregnancy.

Specific groups of immunocompromised patients

 * oncology patients (mainly hematooncology);
 * diabetics;
 * immunosuppressive treatment (corticosteroids), biological treatment;
 * critically ill (ICU);
 * splenectomized patients;
 * patients after transplantation.

Infections in diabetics
Hyperglycemia creates a favorable environment for the survival and multiplication of bacteria, because it is an important substrate for their growth. In addition, it weakens the respiratory rate and the bactericidal function of macrophages. Diabetic vascular damage (diabetic angiopathy) also helps to weaken the immune system, making the vessels less permeable to leukocytes, which reduces their mobility.

Skin and mucosal infections
Of the skin and mucous membrane infections, the most common in diabetics are mycosis, more specifically candidiasis.

Fungal infections Bacterial superinfection
 * candidiasis: recurrent vulvovaginal mycosis in women (candida vulvovaginitis), recurrent balanitis in men;
 * intertrigo: mycosis at the folds of the skin, wet joints, between the fingers (interdigital mycosis), under the breasts, in the axillae, in the inguins;
 * onychomycoccus.

These are secondary infections, where the gateway to pathogenic bacteria is a source of fungal infection. Streptococcus pyogenes is the causative agent of erysipelas, cellulitis or necrotizing faciitis, Staphylococcus aureus leads in the most severe cases to osteomyelitis.

Urinary tract infections are also more common in diabetics. In contrast, diabetes does not increase the incidence of viral infections, respiratory tract infections and pneumonia.

Febrile neutropenia
As febrile neutropenia we refer to a condition in which the number of neutrophilic granulocytes is reduced below 500/mm3(often in the oncological treatment of hematogenous malignancies) and at the same time two febrile peaks above 38 °C are recorded or one febrile peak above 38.5 °C. Febrile neutropenia is one of the conditions in which immediate administration of antibiotics is indicated, although only one third of neutropenic fevers are infectious, the other two thirds are caused by the breakdown of tumor cells or a toxic response to treatment. The antibiotic tazocin (piperacillin + tazobactam) is administered, to which the most common pathogens - gram-negative enterobacteria - are sensitive. Colony stimulating factors (GM-CSF, G-CSF) are also used. In a situation where the granulocyte count is less than 500 / mm 3, colony stimulating factors may be administered prophylactically in the absence of fever. Before starting treatment, blood should be taken for blood cultivation and swabs from the mucous membranes and skin should be performed to determine the cause of the infection.

Complement disorders
Activated components of complement serve as important opsonins and act chemotactically on phagocytic cells. Complement is activated on bacterial surfaces or on an Fc fragment of an antibody. In its insufficiency, macrophages are unable to bind to and phagocytose encapsulated pathogens. Recurrent infections with encapsulated bacteria, such as pneumococcus, meningococcus, gonococcus and hemophilus, are typical of this defect. Infections are more often fulminant. These infections can be prevented by vaccination, as the antibodies produced then replace complement and allow phagocyte binding by binding to pathogens and opsonizing them. Patients are also instructed to seek medical attention immediately for a fever and to be prescribed the broad-spectrum antibiotic co-amoxicillin.