Surgical microbiology in risk patients undergoing abdominal surgery.

INTRODUCTION: Incidence of surgical infection is greater among elderly patients undergoing surgery than among the general population, with a serious compromise regarding morbidity and mortality in this group of patients with increased risk. AIM OF THE STUDY: To determine the microbiological features of surgical infections in patients over 65 years of age compared with those younger than 65. PATIENTS AND METHODS: Over the past 2 years, 2,064 patients underwent surgery in our Department. One thousand three hundred sixty seven of those patients (66.7%) had 65 years of age or less and 688 (33.3%) were over 65. Patient characteristics regarding the type of surgery (degree of contamination) and the nature and type of the condition requiring surgery are reported. One hundred five hundred sixty two samples were submitted for microbiological study. The microbiological infectious pathogens and their characteristics were determined. The Chi-square test was used for the analysis of potential differences related to the age of the patient. RESULTS: The rate of samples sent for microbiological study is higher among patients over 65. In addition, these patients show both quantitative and qualitative differences in their infectious microbiological spectrum, mainly in clean-contaminated, contaminated and dirty surgical procedures. Fungal infections play a significant role in this group of patients. CONCLUSIONS: Facultative gram-negative bacilli, aerobic gram-positive cocci, and fungi are the main pathogens responsible of surgical infections in elderly patients, compared to all other patients, thus requiring specific antibiotic prophylactic and therapeutic regimes.

Infective complications after abdominal surgery in patients infected with human immunodeficiency virus: role of CD4+ lymphocytes in prognosis.

Risk factors associated with surgical infections are related to many events that modulate the immune system and affect the surgical procedure. The aim of this study was to determine the influence of low CD4+ lymphocyte counts in 24 patients with human immunodeficiency virus (HIV) undergoing abdominal surgery. Blood samples were obtained, and the lymphocyte population was evaluated perioperatively, as was the nutritional status of the patient. All the patients received selective antibiotic prophylaxis depending on the surgical procedure performed: (1) clean surgery: splenectomies (n = 8); (2) clean-contaminated: cholecystectomy and biliary tract surgery (n = 8); and (3) contaminated: appendectomy (n = 8). Depending on their CD4 count, two groups were formed: one with 200 to 500 cells/ml (n = 11) and the other with < 200 cells/ml (n = 13). When surgical infection was suspected, surgical drainage and microbiologic cultures were undertaken. For statistical evaluation of the groups ANOVA and the chi-square test were used; p < 0.05 was considered significant. Altogether 14 patients (58.3%) had a wound infection, and the mean (+/- SD) CD4 count in those patients was decreased (221.7 +/- 75.1) compared with that of the 10 patients in the uneventful group (386 +/- 81.2). Surgical infection rates were 50% for clean procedures, 62.5% for clean-contaminated procedures, and 62.5% for contaminated surgery. The group of patients with CD4 counts of < 200 cell/ml had an increased incidence of surgical infection, regardless of the type of surgery (p = 0.002). Thus the surgical infection rates with HIV patients undergoing abdominal surgery are dramatically increased. The CD4 and subsequently depressed neutrophil populations increase the risk of surgical infection during major procedures regardless of the type of surgery performed.

Infective complications after minor operations in patients infected with HIV: role of CD4 lymphocytes in prognosis.

OBJECTIVE: To find out the incidence of wound infection in patients with HIV and reduced counts of CD4 lymphocytes. DESIGN: Open study. SETTING: University hospital, Spain. SUBJECTS: 70 patients with HIV infection and enlarged lymph nodes. INTERVENTIONS: Biopsy of lymph nodes and withdrawal of a sample of blood for counts of CD4 lymphocytes and neutrophils. MAIN OUTCOME MEASURE: Development of infection at the biopsy site, and correlation of infecting organism with culture taken at the time of biopsy. RESULTS: Patients were divided into three groups depending on their CD4 count: more than 500 cells/ml (n = 26), 200-500 cells/ml (n = 24), and less than 200 cells/ml (n = 20). Their neutrophil counts were 5.1, 3.8, and 2.5 x 10(9)/1, respectively. There were found four wound infections (6%); 2 were in the group with more than 500 CD4 cells/ml, and these were caused by Staphylococcus aureus (which had been grown from nodes in 6 patients at the time of biopsy). The other 2 were in the group with less than 500 cells/ml and these were caused by Mycobacterium tuberculosis; cultures of the nodes had shown Staphylococcus epidermidis (n = 3) and M tuberculosis (n = 17). There were no infections in the group with 200-500 CD4 cells/ml, in which S epidermidis (n = 5) and M tuberculosis (n = 8) had been cultured from the lymph nodes. CONCLUSIONS: The CD4 count was of no prognostic importance in the development of wound infection, but severe depression of the CD4 count may increase the risk of atypical wound infections.