Surveillance as a starting point to reduce surgical-site infection rates in elective orthopaedic surgery

Journal of Hospital Infection (2002) 51: 179±184 doi:10.1053/jhin.2002.1256, available online at http://www.idealibrary.com on

Surveillance as a starting point to reduce surgical-site infection rates in elective orthopaedic surgery P. M. Schneeberger*, M. H. W. Smitsy, R. E. F. Zickz and J. C. Willex *Department of Microbiology and Infection Control, Bosch Medicentrum, Den Bosch; yDepartment of Infection Control, and zDepartment of Orthopaedic Surgery, Ziekenhuis Bernhoven, Oss; and xDutch Institute for Healthcare Improvement CBO, Utrecht, Oss, The Netherlands Summary: A surveillance programme was started after a period of high infection rates in an orthopaedic surgical department. The programme was aimed at reducing infection rates in elective hip and knee replacement procedures, and at creating awareness of infection control practices in an acute hospital. Possible causes of the initial high infection rates were analysed and discussed with healthcare workers involved in orthopaedic surgery. No specific cause could be found but substantial logistic improvements were achieved by studying for five years that may have contributed to the reduction of postoperative infections. Surveillance is an important part of any hospital-acquired infection surveillance programme. Its success depends on the ability of the infection control practitioner (ICP) to form a partnership with the surgical staff. Creating a sense of ownership of the surveillance initiative amongst the surgical staff enhances co-operation and ensures that the best use is made of the information generated. It is not possible to eliminate surgical-site infections (SSI) completely, but by a process of sharing information we have been able to influence behaviour to reduce the incidence of SSI. & 2002 The Hospital Infection Society

Keywords: Surveillance; nosocomial infections; orthopaedic infection rates.

Introduction Surgical-site infections (SSI) are associated with a substantial increase in morbidity, resulting in prolongation of hospital stay and monetary costs attributable to the infection.1±3 Reporting surgeonspecific SSI rates to the surgeon and procedurespecific rates to the department of surgery has been shown in a number of studies to reduce SSI rates significantly.4±7 To facilitate the prevention of SSI several countries have started a national surveillance network of SSI.8±13 Received 17 August 2001; revised manuscript accepted 22 May 2002 Author for correspondence: P. M. Schneeberger, Department of Microbiology and Infection Control, Bosch Medicentrum, Nieuwstraat 34, 5211 NL Den Bosch, The Netherlands. Tel.: 031 073 6162875; E-mail:[email protected]

0195±6701/02/070179‡06 $35.00/0

In June 1996, national surveillance of SSI was started in The Netherlands, as part of the PREZIES network [PREventie van ZIEkenhuisinfecties door Surveillance (Prevention of Nosocomial Infections Through Surveillance)]. The aims, organization and results of the Dutch surveillance network have been published recently.14 The main objective of an infection control surveillance network is to provide the participating hospitals and the healthcare professionals concerned with standardized data that can be used for benchmarking. Benchmarking itself can be used for internal quality assessment aiming to reduce SSI rates.15 This article describes the surveillance of SSI from the hospital perspective. We discuss our experience with the surveillance of SSI, which started two years before the start of the PREZIES network. In addition, we report our experience & 2002 The Hospital Infection Society

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with a quality control programme to (re-)implement infection control measures after elective hip and knee replacement procedures in an acute care hospital. Patients and methods The study was carried out at the Bernhoven Hospital, Oss, which is an acute-care hospital with 276 beds providing a wide range of medical and surgical services. Two orthopaedic surgeons carry out all orthopaedic operations. Background A high incidence of SSI was found after major orthopaedic procedures in late 1994. This prompted a retrospective incidence study of all elective hip and knee replacement procedures carried out in 1994. Medical charts and nursing reports were reviewed. In addition, the infection control practitioner (ICP) retrospectively collected and analysed the results of microbiological cultures from orthopaedic patients. SSI were classified by the ICP according to CDC criteria and were categorized into superficial and deep infections.16 To find targets for intervention on infection control practices the ICP evaluated the daily practice of all relevant infection control guidelines. Infection control guidelines The infection control guidelines in our hospital are based on the national guidelines of the Dutch Working Party on Infection Prevention (WIP). The WIP guidelines are considered to be professional standards and are used as such by the Inspectorate of Health and the Ministry of Health, Welfare and Sports. Administration of antimicrobial prophylaxis There are guidelines for antimicrobial prophylaxis in the hospital. Prophylaxis for major orthopaedic operations consists of iv cefuroxime 1.5 g, once 30 min prior to the operation, followed by two doses of iv cefuroxime 750 mg at 6 pm and 6 am. An additional dose of iv cefuroxime 750 mg is prescribed when the operation duration exceeds 3 h. Ventilation In the Netherlands a minimum of 20 air changes per hour of appropriate filtered air is recommended for all operation types, as is the maintenance of

P. M. Schneeberger et al.

positive-pressure ventilation in the operating theatre (OT) with respect to the corridors and adjacent areas.17 Ultra-clean air and exhaust-ventilated suites are not recommended, however during orthopaedic implant operations. There is no Dutch recommendation on the number of colony forming units (cfu)/ m3 allowed for general or orthopaedic surgery because there are no standardized parameters by which to compare microbial levels obtained from cultures of ambient air. According to the FDA, the number of cfu/m3 during clean procedures should be <70.18 In Switzerland for Class I, as required for orthopaedic surgery, cfu/m3 count should be <10.17 However, microbiological sampling of the air in the operating theatre is not carried out routinely in our hospital. Air sampling during surgical procedures was performed during this study, to rule out the ventilation system as a source and for educational purposes. The number of viable airborne microorganisms for a given amount of operating theatre is largely proportional to human activity.19 The air was sampledwithanairsampler(BiotestHycon,Frankfurt am Main, Germany), for 4 min, using tryptic soy agar culture medium (Biotest, Dreieich, Germany). Culturing of swabs from surgical personnel Routine culturing of swabs from surgical personnel is not performed in our hospital. As part of the intervention programme the orthopaedic surgeons and assisting personnel were checked for nasal carriage of methicillin-susceptible Staphylococcus aureus (MSSA). Nasal carriers were subsequently tested for shedding of MSSA. This procedure consists of undressing and dressing in a disinfected room (90  90  220 cm) with four blood agar sedimentation plates in each corner. Plates were incubated routinely for isolation of S. aureus. More than 40 cfu on four plates of identical S. aureus is considered as a positive result, in this case shedding of S. aureus. Reviewing the procedures during operation In order to review procedures during operation, two hip replacement operations were observed and analysed by the ICP for potential breeches in infection control. Prospective incidence surveillance Prospective incidence surveillance was started in January 1995. All patients admitted in the hospital

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for elective hip and knee replacement procedures were included. The number of operations was double-checked with the administration of used implants. The ICP recorded demographic characteristics, patient and operation related risk factors and data on SSI, according to the PREZIES-protocol.14 The ICP also reviewed patients' charts and nursing reports twice weekly, checking the occurrence of SSI, culture results and administration of antibiotics. In cases where the occurrence of a SSI was doubtful, and the administration of antibiotics other than prophylaxis was unclear, the ICP consulted the orthopaedic surgeon. SSI were classified by the ICP according to the criteria of the CDC and were categorized into superficial and deep infections.16 Active post-discharge surveillance of SSI was carried out during a one-year period postoperatively, by reviewing the medical charts after regular follow up at the outpatient department.

Results of the surveillance of SSI were fed back to the orthopaedic surgeons as well as to assisting personnel. To increase the compliance with infection control guidelines, the results of the air samples were linked to the activities performed in everyday practice.

Comparison of hospital infection rates with reference figures

Ventilation

In 1996, our hospital was among the first hospitals to join the PREZIES network. From 1996 onwards data were entered in the WHOCARE software (World Health Organization; Quality of Care and Technologies Unit of the Regional Office for Europe, Copenhagen, Denmark) and submitted to the national PREZIES database. The incidence of SSI was reported for groups of related operations twice a year. This included a comparison of the hospital's own crude and adjusted infection rates to all data present in the national database at that moment. In the adjusted infection rates, differences were accounted for between the hospital's and the national distribution of operations over the National Nosocomial Infections Surveillance (NNIS) index strata.20

Results The results of the baseline measures revealed 12 infections, four deep and eight superficial, among 89 clean operations. Among re-operations (N ˆ 15) those were six infections, three deep and three superficial. All microorganisms isolated are listed in Table I. Operations and infections were evenly distributed among between both surgeons. The administration of antimicrobial prophylaxis for orthopaedic surgical procedures followed hospital protocol.

Air changes in the operating theatre exceeded 20 per hour. Positive pressure with respect to corridors and adjacent areas was ensured by 200 m3/h No pressure gradient was measured between filters. The microbiological sampling results are shown in Table II. During preparation time high cfu counts were recorded in the corridor adjacent to the operating theatres during excessive movement. In the operation Table I Number of infections and pathogens isolated from 1994±1999 Year

Organism

1994 (N ˆ 18)

4  Staphylococcus aureus 4  Pseudomonas aeruginosa 4  Streptococcus epidermidis 2  Streptococcus mitis 1  Peptostreptococcus spp. 2  Mixed infection 1  Clinical infection, culture no growth 2  Pseudomonas aeruginosa 1  Enterococcus faecalis 7  Mixed infection 1  Pseudomonas aeruginosa 1  Escherichia coli 1  Enterococcus feacalis 1  Staphylococcus aureus 1  Mixed infection 1  Clinical infection, culture no growth 1  Staphylococcus aureus 3  Mixed infection 1  Clinical infection, culture no growth 3  Mixed infection

Validation Validation of the surveillance in our hospital was carried out in March 2000 by a team from the PREZIES network. The validation consisted of a process investigation and an onsite prevalence survey. The outcomes of the validation team were compared with the outcomes of the ICP.21

1995 (N ˆ 10) 1996 (N ˆ 6)

Interventions and feedback

1997 (N ˆ 4)

All personnel were (re-)educated on the rigorous adherence to the principles of asepsis twice a year.

1998 (N ˆ 1) 1999 (N ˆ 3)

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Table II Air sampling results (N ˆ 3) in the orthopaedic operation theatre and corridor at various stages of the procedure Procedure

Place

Number of persons present

No. of organisms (cfu/m3)

None Preparation Preparation Preparation None Patient's bed in operation theatre Draping Opening joint Sawing Wound closure Preparation

Door Corridor operation Corridor operation Corridor operation Operation theatre Operation theatre Operation theatre Operation theatre Operation theatre Operation theatre Corridor operation

1±2 3 3±5 3 1 7 7 8 7 8 2

19 170y 6 120z 0 1475 13 38 0 32 6

theatre 1 theatre 1 theatre 2

theatre 5

101* 101 208* 75 6 202 62 12 8 12 13

158* 214* 107 13 0 n.d. 38 0 0 139x 19

*

Door leading to corridor next to operation theatre opened. OT assistant running through the corridor. z Door opened by anesthesiologist. x Door opened for bringing in materials. n.d., Not done. y

theatre high counts were recorded when a patient entered the theatre with a `dirty' bed from the ward, as well as at the end of the operation, where there was increased activity. Culturing of surgical personnel Nasal cultures from seven healthcare workers participating in orthopaedic surgery revealed one MSSA carrier; this person did not shed MSSA. Review of operative procedures Before operation, surgical instruments were set out in the corridor adjacent to the OT and left uncovered until the start of the operation. Orthopaedic operations were performed in the OT closest to the entrance of the corridor. Personnel going to other OT often had to pass these instruments. Due to the lay-out of the OT department, there was no other area for setting out the instruments. Therefore, it was agreed to perform all orthopaedic operations in the operating theatre at the end of the corridor, to minimize the chance of contamination. In addition, all sterile instruments were covered with a sterile drape before the operation. These changes were implemented at the beginning of 1995. We also noticed that beds already used on the wards were taken into the operating theatre. Moreover, we found that OT doors were opened very frequently during operation. On the wards surgical site management complied with hospital guidelines.

Prospective incidence surveillance The results of continuous surveillance of the major orthopaedic operations for six consecutive years are shown in Table III. In our hospital a total of 22 SSI were recorded from 1995 until 1999. These infections were registered between day 5 and 42 after the surgical procedure (mean 12 days). Three infections (13%), of which one was classified as deep, were recorded during post-discharge surveillance, on days 17, 35 and 42. The SSI rate after orthopaedic surgery was 4.1% (1.0% deep; 3.1% superficial).22 Validation of the surveillance A validation team independently studied a random sample of 10 medical records and compared the results with those of the ICP. The process of data collection was evaluated with a questionnaire-based interview. This small validation procedure indicated that use of definitions and the process of data collection complied with the PREZIES protocol.21 Discussion This study shows that surveillance is an important cornerstone of any infection control programme and that (re-)implementing a set of relatively simple infection control measures can significantly reduce orthopaedic SSI rates. To have an effect, initiatives to reduce SSI require the involvement of all staffs, particularly the ICP, who needs to form a partnership with the surgical staff.

Surveillance and orthopaedic infection Table III

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Infection control surveillance (1994±1999) of elective knee and hip replacement procedures

All elective knee and hip operations SSI Overall Deep SSI Superficial SSI Clean operations Deep SSI Superficial SSI Re-operations (possibly infected) Deep SSI Superficial SSI

1994*

1995 (%)

1996 (%)

1997 (%)

1998 (%)

1999 (%)

104 18 7 11 89 4 8 15 3 3

105 10 2 8 97 1 8 6 1 1

132 6 0 6 130 0 5 2 0 1

149 4 0 4 148 0 4 1 0 0

162 1 0 1 160 0 0 2 0 1

191 3 0 3 190 0 3 1 0 0

(17) (7) (11) (4.5) (10) (20) (20)

(10) (2) (8) (1) (8) (17) (17)

(5) (5) (4) (50)

(3) (3) (3) (0)

(1) (1) (0) (50)

(2) (2) (2) (0)

* Data retrospectively collected (%).

The incidence of SSI after orthopaedic surgery in our hospital before 1997 was considerably higher than the average SSI rate of 4.1% in the PREZIES network in the period 1996±1999.22 In 1994 the incidence of SSI was 17.3%. This was a clear indication for the need to prevent SSI. As the isolates were not stored, it was impossible to study the genetic relationships between micro-organisms causing these SSI. In any case, it is probable that various causes played a role in the high incidence of SSI in 1994. Both ventilation and practices in the OT may have an impact on the occurrence of SSI. However, the assessment of ventilation in our hospital did not reveal any breaches. In contrast, adherence to the infection control guidelines during orthopaedic surgery was not optimal. However, improvement to adherence of infection control practices was considered the major intervention strategy. Surgical personnel have been shown to be an important component of our strategies to reduce SSI risk. We tried to improve adherence, by educating healthcare workers and reporting back surveillance data and airsampling results to the surgical team on a regular basis. Furthermore, a system of active surveillance was introduced to monitor the incidence of SSI after elective hip and knee replacements. Potential breeches in infection control were shown to staff, which has helped them adhere to the infection control guidelines. Education on the principles of asepsis for all personnel was (re)-introduced twice a year. Conclusion Surveillance is an important part of any nosocomial infection surveillance programme. Its success depends on the ability of the ICP to form a partnership with the surgical staff. Creating a sense of ownership

of the surveillance initiative amongst the surgical staff will enhance co-operation and ensure that the best use is made of the information generated. It is not possible to eliminate SSI completely, but by a process of sharing information we have been able to influence behaviour to reduce the incidence of SSI.

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