Factors Of Infection In Patients Research Articles

Iron and infection: Clinical experience

Bacterial infection is a significant cause of morbidity and mortality in hemodialysis patients, and a number of studies have implicated iron overload as a risk factor for bacterial infection in these patients. While the underlying cause of increased susceptibility to bacterial infection is not completely understood, evidence suggests that iron overload alters the chemotactic and phagocytic properties of neutrophils, thereby reducing their ability to kill invading pathogens. T-cell function also appears to be altered. In addition, high levels of serum iron may promote replication and dissemination of bacterial pathogens that use iron as a growth factor. With the introduction of recombinant human erythropoietin therapy for hemodialysis patients, the need for red blood cell transfusions has been reduced and iron overload occurs much less frequently. Several recent studies have indicated that iron overload, which is suspected in the presence of high serum ferritin levels, may no longer be a significant risk factor for infection in hemodialysis patients receiving erythropoietin therapy. Major risk factors for infection in these patients include history of bacterial infection, immunosuppressive therapy, and vascular access via catheters rather than by arteriovenous fistula. In addition, anemia has recently been linked to an increased incidence of bacterial infection, particularly in patients receiving erythropoietin therapy. Therefore, repletion of iron stores and maintenance of iron balance without iron overload may prove to be important factors in reducing the incidence of bacterial infections in hemodialysis patients. However, the relationships between iron levels, anemia, and susceptibility to bacterial infection require further investigation. Am J Kidney Dis 34:s30-s34, 1999. Copyright © 1999 by National Kidney Foundation

Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks.

Staphylococcus aureus has long been recognized as an important pathogen in human disease. Due to an increasing number of infections caused by methicillin-resistant S. aureus (MRSA) strains, therapy has become problematic. Therefore, prevention of staphylococcal infections has become more important. Carriage of S. aureus appears to play a key role in the epidemiology and pathogenesis of infection. The ecological niches of S. aureus are the anterior nares. In healthy subjects, over time, three patterns of carriage can be distinguished: about 20% of people are persistent carriers, 60% are intermittent carriers, and approximately 20% almost never carry S. aureus. The molecular basis of the carrier state remains to be elucidated. In patients who repeatedly puncture the skin (e.g., hemodialysis or continuous ambulatory peritoneal dialysis [CAPD] patients and intravenous drug addicts) and patients with human immunodeficiency virus (HIV) infection, increased carriage rates are found. Carriage has been identified as an important risk factor for infection in patients undergoing surgery, those on hemodialysis or CAPD, those with HIV infection and AIDS, those with intravascular devices, and those colonized with MRSA. Elimination of carriage has been found to reduce the infection rates in surgical patients and those on hemodialysis and CAPD. Elimination of carriage appears to be an attractive preventive strategy in patients at risk. Further studies are needed to optimize this strategy and to define the groups at risk.

The Significance of Risk Factors for Infection in Patients Undergoing Lumpectomy and Axillary Dissection

: Controversy concerning the use of prophylactic antibiotics in breast surgery may be due to uncontrolled variability in infection risk among breast procedures, in surgical techniques used by different surgeons, or in length of follow-up at different institutions. In order to control variability, risk factors for postoperative infections after one breast procedure performed by a single surgeon with prolonged follow-up were evaluated. We studied 302 consecutive patients undergoing lumpectomy and axillary dissection by a single surgeon and followed for at least 6 months. Age, height, weight, Quetelet's index, diabetes, prophylactic antibiotics, re-excision of the biopsy site, tumor size, number of involved nodes and overall pathologic stage were evaluated using univariate and multivariate analysis. Eight patients (2.5%) developed wound infections within 30 days of surgery and an additional six (2%) developed infections between 30 days and 1 year. One (2.5%) of 41 patients who received prophylactic antibiotics developed an infection compared to 13 (5.2%) of the 261 patients who did not receive prophylactic antibiotics (chi-square = 0.103, p = 0.749). Eight (8%) of 103 patients diagnosed by ex-cisional biopsy prior to definitive surgery with re-excision of the biopsy site developed infections compared to 6 (3%) of the 199 patients who underwent surgery without re-excision (chi-square = 2.475, p = 0.116). There were also no statistically significant differences between patients with and without infections in age, height, weight, Quetelet's index, diabetes, tumor size, number of involved nodes, or overall pathologic stage. This data does not justify the use of prophylactic antibiotics for lumpectomy and axillary dissection.

Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks.

Staphylococcus aureus has long been recognized as an important pathogen in human disease. Due to an increasing number of infections caused by methicillin-resistant S. aureus (MRSA) strains, therapy has become problematic. Therefore, prevention of staphylococcal infections has become more important. Carriage of S. aureus appears to play a key role in the epidemiology and pathogenesis of infection. The ecological niches of S. aureus are the anterior nares. In healthy subjects, over time, three patterns of carriage can be distinguished: about 20% of people are persistent carriers, 60% are intermittent carriers, and approximately 20% almost never carry S. aureus. The molecular basis of the carrier state remains to be elucidated. In patients who repeatedly puncture the skin (e.g., hemodialysis or continuous ambulatory peritoneal dialysis [CAPD] patients and intravenous drug addicts) and patients with human immunodeficiency virus (HIV) infection, increased carriage rates are found. Carriage has been identified as an important risk factor for infection in patients undergoing surgery, those on hemodialysis or CAPD, those with HIV infection and AIDS, those with intravascular devices, and those colonized with MRSA. Elimination of carriage has been found to reduce the infection rates in surgical patients and those on hemodialysis and CAPD. Elimination of carriage appears to be an attractive preventive strategy in patients at risk. Further studies are needed to optimize this strategy and to define the groups at risk.

Approach to Management of Fever and Infection in Patients with Primary Bone Marrow Failure and Hemoglobinopathies

The characteristic spectrum of infections in patients with aplastic anemia, chronic neutropenic diseases, sickle cell disease, thalassemia, and other hemoglobinopathies are described. The major risk factor for infection in patients with bone marrow failure is the degree of neutropenia and monocytopenia. In patients with aplastic anemia, invasive fungal infections emerge as the major causes of mortality. Life-threatening infections are rare in patients with chronic neutropenic diseases; however, necrotizing enterocolitis due to Clostridium species may be an exception. Bacterial infections, predominantly with encapsulated bacteria, are the most common cause of death in patients with sickle cell disease, especially those who are younger than 5 years of age. Patients with thalassemia and other hemoglobinopathies are particularly susceptible to life-threatening infections with Yersinia enterocolitica as a result of iron overload or of the chelating therapy with desferrioxamine.

Infection in the myelodysplastic syndromes

<h3>PURPOSE:</h3> To determine the incidence, characteristics, and outcome of infection in patients with myelodysplastic syndromes (MDS) and risk factors that may lead to infection. <h3>PATIENTS AND METHODS:</h3> We reviewed infections that occurred in 86 consecutive patients with MDS who received care from 1968 to 1986 at a university-affiliated Veterans Affairs Medical Center. Time lines charting the course of each patient with MDS were created and included infections, MDS subgroup at the time of presentation and at the time of each infection, peripheral neutrophil counts, and therapies for MDS. <h3>RESULTS:</h3> Infections occurred at a rate of nearly one per patient year of observation. Infection rates were associated with MDS subgroup as follows: refractory anemia with or without ringed sideroblasts (RA ± RS) less than refractory anemia with excess blasts (RAEB) less than RAEB in transformation (RAEB-T). The group of RA ± RS patients who had erythroid abnormalities but minimal or no dyspoiesis of other cell lines had the lowest rate of infections. Infection rates were higher in patients with less than or equal to 1,000 neutrophils/μL blood than in patients with greater than 1,000 neutrophils/μL blood for each classifiable MDS subgroup. Neutrophil concentration and MDS subgroup were independent risk factors for infection in patients with MDS. Bacterial pneumonias and skin abscesses were the most common infections. Infection was the most common cause of death during MDS, accounting for 64% of deaths, and was more common than transformation to acute leukemia as a cause of death. <h3>CONCLUSION:</h3> Infection is a common, life-threatening problem in patients with MDS. Neutropenia and MDS subgroup are each risk factors for infection. Clinicians should aggressively evaluate patients with fever and MDS for infection, especially pneumonia and skin infections.

Infection in the myelodysplastic syndromes

purpose: To determine the incidence, characteristics, and outcome of infection in patients with myelodysplastic syndromes (MDS) and risk factors that may lead to infection. patients and methods: We reviewed infections that occurred in 86 consecutive patients with MDS who received care from 1968 to 1986 at a university-affiliated Veterans Affairs Medical Center. Time lines charting the course of each patient with MDS were created and included infections, MDS subgroup at the time of presentation and at the time of each infection, peripheral neutrophil counts, and therapies for MDS. results: Infections occurred at a rate of nearly one per patient year of observation. Infection rates were associated with MDS subgroup as follows: refractory anemia with or without ringed sideroblasts (RA ± RS) less than refractory anemia with excess blasts (RAEB) less than RAEB in transformation (RAEB-T). The group of RA ± RS patients who had erythroid abnormalities but minimal or no dyspoiesis of other cell lines had the lowest rate of infections. Infection rates were higher in patients with less than or equal to 1,000 neutrophils/μL blood than in patients with greater than 1,000 neutrophils/μL blood for each classifiable MDS subgroup. Neutrophil concentration and MDS subgroup were independent risk factors for infection in patients with MDS. Bacterial pneumonias and skin abscesses were the most common infections. Infection was the most common cause of death during MDS, accounting for 64% of deaths, and was more common than transformation to acute leukemia as a cause of death. conclusion: Infection is a common, lifethreatening problem in patients with MDS. Neutropenia and MDS subgroup are each risk factors for infection. Clinicians should aggressively evaluate patients with fever and MDS for infection, especially pneumonia and skin infections.

Postantibiotic Colonization with Clostridium difficile in Nursing Home Patients

Clostridium difficile causes pseudomembranous colitis and is responsible for 20% to 25% of cases of postantibiotic diarrhea. In an earlier study, nursing-home patients with C. difficile infection were noted to have a high mortality rate. Because most of these infected patients had been treated with antibiotics, it was not clear whether this high mortality rate was associated with C. difficile infection or simply with antibiotic treatment. A prospective study was carried out to determine the rate of postantibiotic C. difficile colonization and risk factors for infection in patients in a 233-bed long-term care facility, as well as to determine whether C. difficile infection is associated with increased mortality. During a six-month period 150 courses of antibiotics were prescribed for 108 patients. Stool specimens were collected from 36 (33%) patients following the first course of antibiotic treatment, and 12 (33%) were infected with C. difficile. Risk factors for infection included ward location and stool incontinence. Age, body-mass index less than or equal to 18 kg/m2, and diagnoses of dementia and pressure scores tended to be associated with infection, but not significantly. Early mortality rates did not differ, but 12-month mortality for the infected patients was higher (83% vs 50%, P = .05). Therefore, we conclude that postantibiotic C. difficile infection serves as a marker of death in nursing-home patients, one that can be differentiated from the risk of antibiotic treatment alone. This increased death rate may be related in part to clinically unrecognized pseudomembranous colitis or, alternatively, to absorption of C. difficile toxins or even endotoxin from the gut lumen into the systemic circulation.

14 Infection and Transfusion Therapy in Acute Leukaemia

Granulocytopenia is the single most important risk factor for infection in patients with acute leukaemia. There are limitations to the effective prophylaxis of infection in granulocytopenic patients, but practical measures include the management of the patient in a private hospital room, the requirement of all medical personnel and visitors to wash their hands carefully and to wear masks, restricting the patient to a low-bacteria diet devoid of fresh fruit, vegetables and salads, and the administration of oral antimicrobial agents for gastrointestinal decontamination. When fever develops, empirical therapy with a combination of an aminoglycoside plus an antipseudomonal beta-lactam should be started promptly. A double beta-lactam combination of cefoperazone or ceftazidime plus piperacillin can be substituted if nephrotoxicity is a concern. The addition of empirical intravenous amphotericin may be useful in patients who remain febrile and granulocytopenic on broad-spectrum antibiotics, especially if surveillance cultures indicate fungal colonization. Amphotericin is also the most reliable agent for the treatment of established fungal infections. Acyclovir is not recommended for prophylaxis in acute leukaemia patients but should be reserved for the treatment of well-documented and clinically significant herpes simplex viral infections. During periods of remission, most patients with AML remain free of infection except when they become granulocytopenic again during intensification or consolidation chemotherapy. On the other hand, children with ALL in remission may experience frequent infections unrelated to granulocytopenia as a consequence of their maintenance chemotherapy. Pneumocystis carinii, varicella zoster, and other viruses are common pathogens. Trimethoprim-sulphamethoxazole is effective prophylaxis against Pneumocystis carinii pneumonia in patients with ALL, while intravenous acyclovir is the drug of choice for treatment of varicella zoster infection. Transfusion therapy in the acute leukaemia patient is guided by the patient's peripheral blood counts and degree of sensitization to blood products. Generally, packed red blood cells are given in order to maintain the haematocrit at greater than 30%, while random-donor platelets are administered to keep the platelet count at greater than 20 X 10(9)/l. If refractoriness to platelet transfusions develops, HLA-matched platelets from family members or selected unrelated donors can be used. Similarly, washed or filtered red blood cells may be given to patients with previous and recurrent non-haemolytic febrile reactions to red blood cell transfusions.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence for the presence of double-stranded polynucleotides in the neutrophil inclusions of circulating neutrophils and those which form in the presence of SLE sera

Intracytoplasmic inclusions containing immunoglobulin (Ig) and complement (C3) are found in normal neutrophils (PMN) after incubation with SLE sera (indirect method). These inclusions are believed to be immune complexes removed by phagocytosis from the SLE patients' sera in vitro. Similar inclusions have also been noted in the circulating PMN from patients with SLE (direct method). By both direct and indirect methods, IgG-staining intracytoplasmic inclusions were present in preparations from patients with SLE, chronic liver disease, and Felty's syndrome while none of the normal controls had any inclusions. Using ethidium bromide (EB), a fluorescent stain for double-stranded polynucleotides, red fluorescence was noted in the inclusions of some circulating SLE PMN (36% of patients) and in normal PMN exposed to SLE sera in 67% of SLE patients, suggesting that polynucleotides were part of these complexes. Such staining was not present in control inclusions produced with heat aggregated IgG, nor in any of the patient control groups. Addition of DNA to some SLE sera increased the intensity of the red fluorescence suggesting the presence of antibodies to polynucleotides which can combine with the added DNA. Some originally negative sera were converted to positive by addition of DNA. Purified IgG fractions from SLE sera did not produce inclusions or EB positively unless DNA was added. IgG fractions from normal sera did not produce inclusions with or without added DNA. These findings suggest (1) that normal PMN on exposure to SLE sera develop intracytoplasmic inclusions by phagocytosis of immune complexes containing double-stranded polynucleotides and antibodies to polynucleotides and (2) such complexes may be phagocytosed in vivo as indicated by the presence of inclusions in vivo and contribute to the number of granulocyte disturbances seen in SLE patients. These abnormalities in granulocyte function may be important predisposing factors for infection in patients with active SLE.