An Investigation of hospital-acquired staphylococcal infections and their control

ABSTRACT AN INVESTIGATION OF HOSPITAL-AGQtlRED STAPHYLOCOCCAL INFECTIONS AND THEIR CONTROL ERKMEN, Osman Ph. D. Thesis: in the Graduate School of Health Sciences, Department of Microbiology and Clinical Microbiology Supervisor: Prof. Dr. Sabri GÜNGÖR July, 1994, 116 pages. This study was realized in Gaziantep University, Research and Application Hospital between 1st June 1992 and 31th January 1993. The incidence of nozokomial infections due to Staphylococci which happened after surgery, during the surgical wound care, following the invasive applications and after delivery; the source of Staphylococci and their antimicrobial susceptibility have been examined. The antimicrobial susceptibility rate of isolated microorganisms have been determined by agar disc diffusion method. At the same time MIC and MBC values of S. aureus to different antimicrobial agents have been determined with tube dilution method. Also in vitro activity of gentamicin- and methicillin-resistant S. aureus against vancomycin and quinolone's have been studied. To asses possible modes of transmission and source of S. aureus, cultures were taken from personnel (physician, nurse and other hospital staff)» environmental surface, air of operating rooms, wards and sterilization unit. Totaly 1172 clinical specimens were examined during this 8 months period. 100 nosocomial infections were determined among 87 (56.49 %) patients. Microbial colonizations were found in 67 of 87 patients (43.51 %). 132 (60.27 %) microorganisms from nosocomial infections and 87 (39.73 %) microorganisms from colonized patients of total 219 microorganisms have been isolated. 106 (48.40 %), 57 (26.03 %), 51 (23.29 %) and 5 (2.28 %) of 219 microorganisms were S. aureus, gram negative enteric bacteria, plasma coagulase negative Staphylococci and Candida, respectively. The incidence rate of nosocomial infection was 5.98 % and colonization rate was 4.60 % among admitted patients in the hospital. The most frequent nosocomial infection was wound infections withincidence rate 53.0 % while the incidence rate of urinary tract and throat infections were 28.0 % and 16;0 %, respectively. The methicillin-resistancy rate of S. aureus was 34 % in our hospital. The resistancy rate of & aureus against some other antimicrobial agents were as follows: 74 % to penicillin-G, 36 % to augmentin, 12 % to imipenem, 21 % to cephalothin, 16 % to chloramphenicol, 2 % to vancomycin, 24 % to gentamicin and 3 % to quinolone's. 71 (66.98 %) strains of 106 S. aureus were typable with standard set of 21 international bacteriophages. 36.6 % of the strains were typable with group III phages, 19.7 % with group II phages, 22.5 % with group I phages, 5.6 % with miscellenous phages and 15.5 % with mixed groups. Group III strains were common and type 42E strains (16.90 %) was predominant strains among our isolates. 85 (61.59 %) strains of 137 S. aureus isolated from hospital staff, surface area and air were typable with 21 bacteriophages. Type 42 E was predominant strains among S. aureus isolated from hospital personnel and air while 52A/79 were predominant among isolates from hospital surface area. In our study, S. aureus wound infections were predominant among surgical wards. S. aureus was also predominant bacteria in wound and throat infections while gram negative enteric bacteria were predominant in urinary tract infections. Susceptibility rate of S. aureus to vancomycin and quinolone's were higher. In vitro studies also showed that these two agents are drugs of choice in the treatment of nosocomial infections with S. aureus. The nosocomial infections are present as an important problem in our hospital. The surveillance of nosocomial infections require a group studies, so when "Infection Control Committee" is to be set up, the nosocomial infections can be controlled and decreased. Key Wards Nosocomial Infection; S. aureus; Methicillin-Resistant S. aureus; Pk Negative Staphylococci', Gentamicin- and Methicillin-Reşistant S. aureus; Bacteriophage. vi