A before-after intervention cohort study was conducted during two years starting from August 2013 at the OGD of DRRH. The study included a pre-intervention survey (PRE-Int), an intervention and a post-intervention survey (POST-Int). Each of the two surveys lasted three months and were conducted during the dry season. The study was directly supported by the Resource Centre for Infectious Diseases (RCID) of DRRH. The intervention included literature-based education, on-the-job training and the establishment of an AMS multidisciplinary team.
Study sites and study population
DRRH has a bed capacity of 580 and 5 operating theatres, of which one is dedicated to the OGD. Data available from 2013 to 2015 report an average number of 14,800 deliveries per year, with approximately 2,700 (18%) CS.
A four-step protocol was adopted (Fig. 1). The first step consisted of the PRE-Int, enrolling all consecutive women undergoing a CS during three months from August 19, 2013, with a 30 day-post-CS follow up. During the second step, data from the PRE-Int were shared with the hospital staff. Thereafter, an AMS Multidisciplinary Team was set up, including an Infectious Diseases (ID) Specialist, the head of OGD, a pharmacist, an IPC nurse, a clinical microbiologist and a representative of the hospital management. These professionals identified the prevention measures and the interventions to be prioritized as follows: a) implementing the reporting system; b) strengthening the supply chain for antibiotics, disinfectants and operating room/laboratory disposables; c) proper surgical hand preparation; d) administration of a pre-operative prophylaxis 30–60 minutes before the incision; e) optimizing the appropriateness of antibiotic prescription in the post-operative period; f) improving operating theatre discipline and organization and g) strengthening the capability and capacity of the Microbiology Unit. In particular, the importance of the prophylaxis was underlined. In fact, before the intervention, almost every woman received an antibiotic course lasting 8–10 days post-CS, irrespective of the presence of risk factors or signs/symptoms of infection. The antibiotic course usually included 3 days of intravenous ceftriaxone plus metronidazole, followed by oral penicillin (amoxicillin alone or ampicillin/cloxacillin) plus metronidazole for at least 5 days. The timing was highly variable, ranging from 1 to 24 hours post-CS. A pre-operative prophylaxis with ampicillin 1 g given 30–60 minutes before the incision was suggested, based on drugs availability. The third step consisted of the introduction of the prevention measures into clinical practice and in the organization of seminars focusing on IPC and AMS. Literature-based education was encouraged. On-the-job training was also conducted under the supervision of a pool of ID specialists and clinical microbiologists. Standard Operating Procedures (SOPs), recent publications, guidelines, expert consultation and mentorship on data collection were available at the RCID from Monday to Friday. The last step included the POST-Int, enrolling all consecutive women undergoing a CS during three months starting from April 1, 2015, followed by 30 days post-CS surveillance.
Survey and laboratory procedures
A 30-day follow up was conducted, including a variable number of visits starting from day 7 post-CS. The aim was to have at least one post-operative contact with the patient, either by clinical visit or telephone . Patients were considered lost to follow up after five unsuccessful attempts by telephone. At each visit, an examination of the wound was performed by an ID specialist and the antibiotic treatment history was collected. In case of telephone contact, a structured interview was used to detect SSIs. If SSI was suspected, the patient was referred to the nearest health centre. The classification of SSIs was done according to CDC definitions . In any case, if SSI was suspected, a wound swab was collected. The specimens were processed soon after collection. Briefly, the specimens were inoculated on blood agar and MacConkey agar and incubated aerobically. Petri dishes were checked after 24 and 48 hours for bacteria detection and identification. Antimicrobial susceptibility of isolates was determined using disc diffusion method. The antibiotics tested included: oxacillin (1 µg), ampicillin (10 µg), amoxicillin (25 µg), amoxicillin/clavulanate (20 µg + 10 µg), clindamycin (2 µg), erythromycin (15 µg), ciprofloxacin (5 µg), trimethoprim-sulfamethoxazole (1.25 µg + 23.75 µg), ceftriaxone (30 µg), chloramphenicol (30 µg), gentamicin (10 µg), tetracycline (30 µg). Vancomycin 5 µg, ceftazidime 10 µg and meropenem 10 µg were also tested in the POST-Int study. Based on Kirby-Bauer susceptibility test, gram-negative bacteria were classified as multidrug resistant organisms (MDROs) if resistances to amoxicillin/clavulanate, ceftriaxone (or ceftazidime), and/or gentamycin, and/or ciprofloxacin were detected. MRSA were identified by using the diffusion method with oxacillin disc [15, 16].
The primary outcome was to report the CS-SSIs rate. The secondary outcome was to assess the determinant factors of SSIs before/after the intervention and overall. The microbiological characteristics and patterns of AMR were determined to provide an overall picture of the SSIs.
Data collection and statistical analysis
All consecutive CS performed during the study period were eligible for inclusion in the analysis. Data were retrieved from different sources, including: hospital medical records, antenatal cards, surgical notes and structured telephone interviews following a standardized questionnaire. Data collection was done by trained staff from the RCID and entered in a dedicated Microsoft Excel dataset. Comparison of mean values was done using the Student’s t test. The χ2 test and Fisher’s exact test were used to explore univariate associations between categorical variables. Log binomial regression model was adopted for multivariate analysis to detect the association between predictor variables and SSIs and to assess the impact of the intervention on outcomes. Co-variates with p < 0.1 were considered for multivariate analysis. Odd ratios and confident intervals were computed. A p < 0.05 was considered significant. The statistical analysis was performed using SPSS (software version 21, NY, U.S.A.).