Journal of Infection (I99 r) 23, I6I-I67

The use of routine wound swabs and Kardex review for the surveillance of surgical wound infections W. H. Yung,*~; W. H. Seto* a n d C. J. P r i t c h e t t t

Departments of * Microbiology and t Surgery, University of Hong Kong, Hong Kong Accepted for publication 23 January I99I Summary Prospective post-operative wound surveillance was carried out in two phases o n I 2 8 5 patients. A total of 12o infections were documented. In phase I a review of routine swabs and Kardex was conducted in parallel with continuous surveillance. In this phase continuous surveillance detected 31/35 infections and routine swabs and Kardex methods picked up 28/35 infections. In phase z continuous surveillance was not carried out and routine swab and Kardex review detected 78/85 infections. Overall II infections were documented following discharge. Continuous surveillance is sensitive but laborious. The method described here would enable infection control nurses to visit patients in whom infections are more likely to occur, and still provide reliable and accurate rates of infections.

Introduction Post-operative w o u n d infection remains a major clinical problem in hospitals. T h e surveillance of surgical w o u n d infection is r e c o m m e n d e d by both surgeons 1 and infection control personnel, 2 and various m e t h o d s have been described. One approach that is widely recognised is continuous surveillance. 3.4 T h i s requires the prospective evaluation of all surgical wounds by the infection control nurse ( I C N ) and is therefore labour intensive. Other surveillance m e t h o d s , which are less demanding, include self-reporting by surgeons and ward-staff 5 and the retrospective evaluation of clinical records. ~ H o w e v e r , such data is often incomplete, and m a y be influenced by personal bias. 7 A m e t h o d which can reliably select patients that are more likely to have infection could reduce the n u m b e r of w o u n d s that need to be inspected by the I C N . 8 One such m e t h o d reported from the U.S.A. involves the regular review of the n u r s i n g care plan (Kardex) 9 to select high-risk patients on the basis of certain p r e d e t e r m i n e d criteria. H o w e v e r , the K a r d e x review is d e p e n d e n t on the quality of the data recorded in the Kardex, and in m a n y countries, this m a y not be as complete and comprehensive as that in the U.S.A. An assessment of the reliability of the K a r d e x review m e t h o d outside the U.S.A. was therefore felt to be worthwhile. We also studied the potential value o f a new m e t h o d to select patients for w o u n d inspection based on the detection of leucocytes from swabs taken f r o m all post-operative wounds. T h e sensitivity of both surveillance m e t h o d s was ~: Address correspondence to : Dr Yung Wai Hung, Department of Microbiology, University of Hong Kong, Pathology Building, Queen Mary Hospital Compound, Hong Kong, oi63-4453/9I/o5oi6t +07 $03.00/0

© I99I The British Society for the Study of Infection

I62

W. H. Y U N G E T A L .

determined in the initial phase of the study by concurrent continuous surveillance. Methods

T h e study was conducted in Queen Mary Hospital, Hong Kong from March ~987-August I988. T h e University Surgical Unit has 15o beds and all patients who had general surgery in the unit were included in the study. For the study, the definition of wound infection was the discharge of pus, with or without a positive culture. 1° T h e study was conducted in two phases. P h a s e I. C o m p a r a t i v e a s s e s s m e n t o f s u r v e i l l a n c e m e t h o d s

Phase I was conducted as a research project in the surgical department, and Kardex review, routine wound swabs and continuous surveillance were carried out in parallel for 4 months. As it was a preliminary assessment of a surveillance programme, no official announcement was made in the surgical department. Direct continuous surveillance was adapted from Olson e t a l . 4 All surgical wounds were inspected daily by the infection control nurse (ICN) from the third post-operative day, until the patient was sent home, or until wound infection occurred. Information on the operation was also obtained from the surgeon's operation notes. When patients were sent home, they were each given a card, with the ICNs office telephone number and address, requesting them to contact her if there was pain, swelling or discharge from the wound. Patients who were sent home before the removal of stitches, were contacted by telephone after 3o days, to assess whether infection had occurred. Unlike the U.S.A., the content of the Kardex in Hong Kong is not regulated by any accreditation standards or rules, and the Kardex records are often brief and incomplete. Nevertheless, the Kardex was reviewed daffy by the I C N for evidence suggesting wound infection. Any of the following criteria alerted the I C N to inspect the wound (a) a wound swab ordered by the surgeon, (b) a request by the surgeon for the removal of one or two stitches, (c) initiation of antibiotic therapy, (d) change in the type of dressing, (e) a report of discharge or inflammation of the wound, (f) temperature greater than 38 °C, or (g) a wound was inspected by the surgeon for suspected infection. A daily attempt was also made to locate the 'dressing' nurse and to obtain verbal reports regarding the state of the wound. Ward nurses were requested to swab routinely all surgical wounds on the third and seventh post-operative days, or at the time of hospital discharge if this occurred earlier. Swabs were also taken from all discharging wounds. All swabs were submitted for a Gram-stained smear and those swabs taken from discharging wounds were also cultured. Wounds having detectable leucocytes (WBC) on smear were inspected by the ICN. T h e routine swab protocol was written down as a nursing order, and all ward nurses were familiarised with this before surveillance was initiated. On a weekly basis, the list of operations performed was obtained from the theatre record book. This list had two major functions. A check could be made on whether all wounds had been swabbed, so that routine swabbing could be completed for those that were inadvertently missed. T h e list was also used for deriving the denominator for the calculation

Surveillance of surgical wound infections

I63

of infection rates. Surveillance for patients who were sent h o m e was similar to the continuous surveillance m e t h o d . H o w e v e r , a n u m b e r of patients with a positive smear left the hospital before their w o u n d s were inspected and these were also contacted b y telephone. A n attempt was made to call back all apparently infected cases for inspection b y the I C N . Stringent criteria were used for recognising w o u n d infection after hospital d i s c h a r g e - - e i t h e r pus was o b s e r v e d b y the I C N or the infection was diagnosed by a doctor. It was already an established departmental policy for surgeons to report all w o u n d infection on a weekly basis and this data was also collected. Phase 2

Phase 2 was initiated 5 m o n t h s after the completion of phase i, and lasted for a total o f 9 months. In the second phase only routine w o u n d swabs and K a r d e x review were used in the surveillance programme. T h e surveillance p r o g r a m m e was n o w formally a n n o u n c e d in the surgical d e p a r t m e n t and all required procedures were established as routine ward procedures. O n e aim of phase 2 was to assess w h e t h e r results comparable with phase I could be obtained w h e n the p r o g r a m m e was formally instituted in the department. T h e K a r d e x review was shown to be rather ineffective in phase I, and phase 2 was also designed to evaluate w h e t h e r this surveillance m e t h o d could be enhanced b y staff education. Before the initiation of the formal surveillance p r o g r a m m e , the I C N c o n d u c t e d educational seminars on the K a r d e x record for all w a r d times. T h e y were especially requested to record features that w o u l d alert the I C N to inspect the ward for suspected infection. Analysis of data

T h e w o u n d s were classified b y the categories established by the American College o f Surgeons. tl T h e r e was h o w e v e r one modification in this study. Operations in which there might have been a major break in technique or gross spillage w o u n d were classified as ' C l e a n - c o n t a m i n a t e d ' instead of ' C o n t a m i n a t e d '. Results

In the study, a total of I285 w o u n d s were surveyed, and I2o (9"3 %) w o u n d infections were detected. T h e results o f the various surveillance m e t h o d s are shown in T a b l e I. In phase I, a total o f 35 (8"5 %) infections were detected, four of which were detected after the patients were discharged. I f continuous surveillance was taken as the ' G o l d s t a n d a r d ' , then the sensitivity index was 90 % for routine w o u n d swabs, 35 % for K a r d e x review and 32 % for the surgeons' self-report. Eighty-five infections were detected in phase 2, seven of which were detected after the patients were discharged. T h e infection rate in phase 2 was 9"7 % and is comparable to the 8"5 % in phase I [P = o'5, Chi square (X ~) = 0"46]. In phase i, the K a r d e x review could identify only I I (39 %) of the 28 infections detected b y routine w o u n d swabs, b u t in phase 2, this had increased to 50 (68 %) out of the 74 infections detected b y routine w o u n d swabs. T h i s was statistically significant ( P < 0"05, X~ = 6"8). F u r t h e r m o r e , in

164

W . H. Y U N G

ET AL.

T a b l e I The detection of wound infection by different surveillance methods Wound infections detected (%) Phase i 4 months (I) Continuous surveillance by ICN (2) Surgeon's self-report (3) Kardex review (4) Routine wound swabs (5) Routine wound swabs and Kardex (6) Infection detected after discharge* Total infections detected

(n = 4IO)

Phase 2 9 months (n = 875)

31 (7"6)

Not done

lO (2"4) 11 (2"7) 28 (6-8) 28 (6"8)

35 (4) 54 (6'2) 74 (8'5) 78 (8"9)

4 (1)

7 (0.8)

35 (8"5)

85 (9"7)

* Due to readmission (two cases), patient's self-report (five cases) and ICNs phone followup (four cases). T a b l e I I Wound classes and pathogens isolated from the I2O infected wounds

(a) Wound class Clean Clean contaminated Contaminated Dirty

Number surveyed

Infected (%)

132 578 292 283 1285

2 (I'5) 53 (9 .2 ) 24 (8'2) 41 (15) 12o (9'3)

(b) Pathogens isolated (%) of isolates

Staphyloccus aureus Eseherichia coli Klebsiella/Enterobacrer spp.

49 (21) 37 (16) 23 (IO)

Emerococcus

22 (IO)

Pseudomonas aeruginosa Proteus spp.

18 (8) 13 (6) 5 (2) 64 (28)

Anaerobes Others

p h a s e 2, t h e K a r d e x r e v i e w i d e n t i f i e d f o u r i n f e c t i o n s t h a t w e r e m i s s e d b y r o u t i n e w o u n d swabs. T a b l e I I shows t h e d i s t r i b u t i o n o f i n f e c t e d w o u n d s a c c o r d i n g to w o u n d class a n d t h e p a t h o g e n s t h a t w e r e isolated. T h e i n f e c t i o n rate f o r cleanc o n t a m i n a t e d w o u n d s (9"2 ~/o) was h i g h e r t h a n t h a t f o r c o n t a m i n a t e d w o u n d s (8-2 % ) . T h e h i g h e s t rate was I5 % for d i r t y w o u n d s . Staphylococcus aureus was t h e m o s t f r e q u e n t p a t h o g e n ( 2 1 % ) f o l l o w e d b y Escherichia coli ( I 6 ~/o).

Surveillance of surgical wound infections

I65

Table I I I Number of wounds surveyed when using the routine smear and

Kardex review Number of wounds surveyed (%) Phase i n = 41o

(I) Wounds with positive routine smear (with WBC present) (2)

W o u n d s w i t h negative smear, but alerted by K a r d e x review

Total

Phase 2 n = 875

71

191

3

22

74 (18) 213 (24)

Table I I I shows the number of wounds that were inspected by the I C N in relation to the routine wound swab and Kardex review methods of surveillance. Only 74 (~8 %) of 4Io phase I patients and 213 (24 %) of 875 phase 2 patients, required inspection. T h e accuracy of the operation theatre (OT) records was assessed because this was used as the denominator for the calculation of inspection rates. T h e O T records in phase I were compared with the surgeon's operation records obtained during continuous surveillance. There was a 7 % discrepancy in the names of the procedures, which would have affected the classification of the wounds (e.g. an inflamed appendix was not reported as perforated in the O T records). However, the identities of the operating surgeons and the types of operation recorded in the O T record fully corresponded to data in the surgeon's own operation notes. Therefore, the inaccuracies in the name of the operation would not have affected the calculation of surgeon-specific rates. Discussion

Surgical wound surveillance is a difficult and exacting task, and there is still demand for a surveillance method which is both economical and accurate. In this study, a new method of wound surveillance by routine swabs was evaluated. W o u n d infection is normally accompanied by the production of leucocytes, 12 and their presence in the smear was used for selecting patients for further inspection by the ICN. Phase I was designed to assess the accuracy of this method by comparing it with the continuous surveillance method. In this phase, routine wound swabs were able to detect 90 % of the infections identified by continuous surveillance. It is probable that routine swabs were just as effective in phase z. T h e infection rate in phase 2 was comparable to that of phase I. Kardex review was not as effective. In phase I the sensitivity index was only 35 % because the Kardex records in the hospital were incomplete. Since a few infections were missed by routine wound swabs in phase I, it was felt that the Kardex review should be incorporated in the formal hospital surveillance programme in phase 2, as a back-up. In phase 2, after instructing the nurses

I66

W.H. YUNG

ET AL.

to upgrade the content of the Kardex, more infections were identified by Kardex review and indeed four infections that would have been missed by routine swabbing, were detected by this system. A feature of the surveillance programme in phase 2 was a reduction of the workload, when compared with the continuous surveillance method. For the purpose of illustration, a model was developed to estimate the amount of reduction in terms of work hours. This model was used to estimate the workload reduction in phase 2, assuming that after the operation, a week of surveillance was needed for all patients. In continuous surveillance, each visit to the patient, which included wound inspection and a review of the patient's case notes, required a total of I5 rain/day. A week of surveillance (from the third post-operative day) would incur a total of I'25 h per patient. T h e total time expended for visiting 875 patients in phase 2 would be Io94 h (875 x I'25). In surveillance by routine swabs and Kardex review, only 24 % of the wounds were inspected, and this would require only 263 h. T h e time expended on the processing of smears, which was done twice weekly, was also taken into account. T h e American College of Pathologists allocated 5"I min for the performance of a single smear, 18 and for the 875 cases, it would amount to I49 h/week. Therefore, for the week after the operations, there would be a total saving of 682 h (IO94-263-I49 h). A possible alternative to the surveillance protocol in phase 2 would be to omit routine swabs, and to submit swabs for wounds with a purulent discharge only. Such a protocol was in fact assessed before the initiation of phase I, but the ward nurses submitted swabs for only about 5o % of these wounds. Probably, in a busy ward, compliance by ward nurses would be difficult unless the procedure (i.e. the wound swab) were made routine. As previously reported by Polk 7 and Condon et a l . , 1 this study reaffirms that infection rates derived from self-reported data of surgeons could be grossly inaccurate. T h e surgeons' self-reported infection rate in phase I had a sensitivity of only 32 %. In this study, as recommended by the Surgical Infection Society, 13 surveillance was conducted for up to 30 days after discharge and 9 % of all infections were detected in the post-discharge period. Comparable figures have been reported, but higher percentages have also been published. 14 However, in these studies, data were obtained mainly by questionnaire, and less stringent criteria for infections were used. Brown et a l . , 15 have pointed out that questionnaires can be a rather subjective method for detecting wound infection after discharge, and therefore over reporting cannot be excluded. T h e distribution of the different pathogens isolated in this study was rather similar to other reports, 16 but infection rates for the different wound classes were quite different. T h e infection rate for clean-contaminated wounds (9.2 %) was higher than that of contaminated wounds (8"2 %). This was not unexpected because a modification was made to the classification criteria proposed by the American College of Surgeons. n T h e denominator was obtained from data in the O T record books in which spillages and breaks in technique were not documented. Therefore, operations with such mishaps would be classified under 'clean-contaminated' instead of 'contaminated'. It was felt, however, that this modification was superior in one aspect: spillages and breaks in technique should be the responsibility of the surgeon, and the

Surveillance of surgical w o u n d infections

I67

w o u n d s h o u l d n o t b e r e g a r d e d b y s u c h m i s h a p s to a c a t e g o r y in w h i c h a h i g h e r i n f e c t i o n r a t e is e x p e c t e d . T h e r e a r e p r e s e n t l y , m e t h o d s o f w o u n d classification w h i c h t a k e i n t o a c c o u n t v a r i o u s r i s k f a c t o r s , o t h e r t h a n c o n t a m i n a t i o n , s I t is r e c o g n i s e d t h a t these methods may be more precise but for the present baseline study, a t r a d i t i o n a l a p p r o a c h w a s a d o p t e d . F u r t h e r m o r e , t h e s u r g e o n s in t h e h o s p i t a l are m o r e f a m i l i a r w i t h t h e p r e s e n t classification s c h e m e a n d t h e y find t h a t t h e p r e s e n t s u r v e i l l a n c e p r o g r a m m e is q u i t e a c c e p t a b l e . T h i s is i m p o r t a n t b e c a u s e a m a j o r r e a s o n f o r s u r g i c a l w o u n d s u r v e i l l a n c e is to g e n e r a t e s u r g e o n specific rates. T h e r e a r e v a r i o u s r e p o r t s i n d i c a t i n g t h a t t h e f e e d b a c k o f t h e s e r a t e s are e f f e c t i v e in r e d u c i n g t h e w o u n d i n f e c t i o n r a t e in t h e h o s p i t a l . 1' 17 S t u d i e s are p r e s e n t l y b e i n g c o n d u c t e d to e v a l u a t e w h e t h e r s u c h f e e d b a c k is really efficacious. References

I. Condon RE, Schulte WJ, Malangoni MA, Anderson-Teschendorf MJ. Effectiveness of surgical wound surveillance. Program Arch Surg I983 ; H8: 303--3O% 2. Gardner JS. Guidelines for prevention of surgical wound infections 1985. Centers for Disease Control, U.S. Department of Health and Human Service, Atlanta, Georgia, USA. 3. Cruse PJE, Foord R. A five-year prospective study of 23649 surgical wounds. Arch Surg I973; I o 7 : 2o6--zio. 4. Olson M, O'Connor M~ Schwartz ML. Surgical wound infection--a five-year prospective study of 2oi93 wounds at the Minneapolis VA Medical Center. Ann Surg 1984; *99: z53-259. 5. Gastrin B, Lovestad A. Postoperative wound infections--relation to different types of operative and wound contamination categories in orthopaedic surgery. J Hosp Infect I989; I3 : 387-393. 6. Krukowski ZH, Matheson NA. Ten-year computerized audit of infection after abdominal infection. Br ff Surg I988; 75: 857-86I. 7. Polk HC. The value of a nurse epidemiologist in the control of surgical infection. Surg Clin N Am I975; 55: I277-I2828. Haley RW, Culver AH, Morgan W M , White JW, Emori TG, Hooton TM. Identifying patients at high risk of surgical wound infection. Am ff Epidemiol I985; , z , : 2o6-215. 9. Farber BF, Wenzel RP. Postoperative wound infection rate, results of prospective statewide surveillance. Am ff Surg I98O; *4o: 343-346. Io. Centers of Disease Control. Outline for surveillance and control of nosocomial infections, I974. U.S. Department of Health, Education and Welfare, Atlanta, Georgia, United States. I I. Altemeier WA, Burke JF, Pruitt BA, Sandosky WR. Manual on control of infection in surgical patients. 2nd ed. JB Lippincott, I984: 28. 12. Meakins JL, Hohn DC, Simmons RL, Dunn DL, Hunt TK, Kinghton DR. Host defenses. In: Simmons RL, Howard RJ, eds. Surgical infections diseases. 2nd ed. New York: Appleton-Century-Crofts I3. Condon RE, Haley RW, Lee JT, Meakins JL. Does infection control infection? Panel discussion--Surgical Infection Society I987. Arch Surg 1988; I23: 250-256. 14. Burns SJ, Dippe SE. Postoperative wound infections decided during hospitalization and O T after discharge in a community hospital. Am J Infect Control 1983; II:226-229. I5. Brown RB, Bradley S, Opitz E et al. Surgical wound infection documented after hospital discharge. Am J Infect Control 1987; xt: 54-58I6. Centers for Disease Control. Nosocomial infection surveillance, i98o-I982. In: CDC surveillance summaries. I983 ; 32 : I SS-I6SS. I7. Mead PB, Pories SE et al. Decreasing the incidence of surgical wound infections-validations of surveillance---notification program. Arch Surg 1986; IZX: 485-461. I8. Manual for Laboratory Workload Recording Method. Publication of College of American Pathologist 1985: 34-