Surveillance of infection burden in residential aged care facilities

Infection surveillance is a crucial component of an integrated infection control program, providing timely feedback about infection prevention issues that is geared towards decreasing the burden of infection within health care facilities.1 Data from overseas suggest there is a considerable infection burden among aged care residents.2-6 The Aged Care Standards and Accreditation Agency Ltd has highlighted that surveillance is required in Australian residential aged care facilities (RACFs), but there are few published studies describing the epidemiology of health care-associated infection (HCAI) and antimicrobial use.7,8

A recent Australian study highlighted a concern about emergence of antimicrobial-resistant organisms among RACF residents.8 The study, however, did not describe the infection burden and the associated antimicrobial prescribing patterns among this population. Although some overseas studies report extensive prescribing of broad-spectrum antibiotics,9-11 differences in clinical practice are likely in Australia.

Accordingly, we explored the patterns of common infections and use of antimicrobial agents in four Australian RACFs using internationally recognised criteria.12 Recognition of the infection burden among residents in this long-term care setting will help to identify infection prevention priorities and guide antimicrobial stewardship efforts.

Cephalexin, trimethoprim, amoxycillin–clavulanic acid and roxithromycin accounted for 62% of all the courses prescribed (Box 3). UTI was the most common indicator for antimicrobial use (in 41% of courses), followed by LRTI (in 26%), SSTI (in 12%), URTI (in 8%) and eye infection (in 8%). Box 4 shows antimicrobial prescribing patterns for three major sites of infection (ie, UTI, LRTI and URTI combined, and SSTI). Only about 5% of antimicrobials were prescribed for other indications such as ear and mouth infection, gastroenteritis, bloodstream infection and unexplained febrile illness. Around 11% of all antimicrobials prescribed for UTIs were broad-spectrum antibiotics, which included norfloxacin, ciprofloxacin, ceftriaxone and gentamicin. Indwelling catheter-related (IDC) UTI contributed to about 20% of all episodes of UTI; prescribing patterns for both non-IDC and IDC UTIs were similar. Antimicrobials were routinely prescribed for URTI and bronchitis (constituting up to 31% of overall antimicrobial use). Similar prescribing patterns were observed for episodes that fulfilled McGeer criteria and those that did not.

Of 659 episodes for which patients were treated with antimicrobials, only 238 episodes (36%) had documentation that clinical specimens were obtained. Clinical specimens were infrequently collected for most types of infection (Box 5). Conversely, collection of urine specimens was documented for 72.2% of UTI episodes.

The incidence of HCAIs from 2006 to 2010 in four RACFs in Melbourne was comparable to rates reported in the literature, however, despite feedback of infection rates to staff, we did not find evidence of notable improvement in infection burden over time. We found a significant burden of antimicrobial use and identified URTI, bronchitis and asymptomatic bacteriuria as areas where use was likely to be inappropriate.

Our results indicate that systematic infection surveillance can be established and sustained in Australian RACFs using internationally established criteria,12 although there are currently no systematic surveillance systems for infection in RACFs in any Australian jurisdiction. The only two published Australian studies that have examined HCAI rates in this setting were conducted over a 9-year period in a Sydney network and as a 6-month pilot study in a rural Victorian region.7,16 Both studies used the McGeer criteria and reported rates of infection at 3.1 and 2.2 infections per 1000 OBD, respectively. These rates are of the same magnitude as infection rates reported in studies from the United States and European countries of 1.5–9.5 infections per 1000 OBD, based on the McGeer criteria.2-6,14 The average rate and types of HCAI in our study were generally comparable to the reported literature, except for the rate of pneumonia, which was considerably lower than that in some studies.11,17,18 We found that chest x-rays, required to fulfill criteria for pneumonia, were often not performed in this patient population, suggesting that the low rate may reflect differences in clinical practice, rather than a true difference in pneumonia rate. The rate of gastroenteritis (0.15 episodes per 1000 OBD) was lower than that reported in one other local study (0.29–1.42 episodes per 1000 OBD).19

Importantly, the rates of HCAI remained relatively stable over time, with the exception of two outbreaks reported in 5 years, suggesting that routine surveillance and feedback of infection-related issues did not result in noticeable improvement in preventing infections. Routine surveillance without more proactive measures may not effectively improve the burden of HCAIs and antimicrobial use over time. Most infection prevention guidelines are designed for use in hospitalised patients with a high prevalence of invasive devices. Work is required in developing and validating infection prevention policies for the RACF setting.

There was a significant burden of oral antimicrobial use in this population, with a high proportion of treated episodes not meeting infection criteria, reflecting the difficulties in clinically assessing this patient popula-tion. The antimicrobial burden in the RACFs we studied (7.07 courses per 1000 OBD) was mid-range compared with those reported in overseas studies (2–15 courses per 1000 OBD).10,17,20,21 Data from Australian RACFs for benchmarking are lacking. The rate of antimicrobial use cannot easily be compared with hospital-based and community-based studies, owing to differences in surveillance methods. Nonetheless, if the average duration of an antimicrobial course was around 7 days, the use rate could be converted and would approximate 50 defined daily doses (DDD) per 1000 OBD, which is higher than the estimated use in the community (about 25 DDD/1000 population days)22 but much lower than the estimated use in large Australian hospitals (about 1000 DDD/1000 OBD).23

In our study, the considerable proportion of antimicrobials prescribed for episodes that did not meet the McGeer criteria was similar to that reported elsewhere.8,20 Although the McGeer criteria are well established for epidemiological comparison, antimicrobial use in patients not meeting these criteria may not always be inappropriate. Nevertheless, it was noted that all episodes of URTI and nearly all of bronchitis led to routine prescribing of antimicrobials without further diagnostic investigation to confirm bacterial aetiology, contrary to recommendations in the national Antibiotic Therapeutic Guidelines.24 Similarly, the use of antimicrobials for asymptomatic bacteriuria is not recommended. The prescribing of antimicrobials for asymptomatic bacteriuria is of particular concern because the emergence of multiresistant organisms in the RACF setting25,26 is often attributable to extensive or inappropriate use of antimicrobials and may result in the RACFs becoming a reservoir for multiresistant organisms. Barriers to improving the quality of antimicrobial prescribing include the complexities of assessing elderly patients due to atypical illness presentation, lack of timely investigations to guide therapy, and the large number of health care providers involved in the care of RACF residents.

Several sources suggest that fluoroquinolones were the most commonly prescribed antibiotics for common infections in the RACF setting overseas.9,10,27,28 However, our data show that cephalexin and trimethoprim were used to a much higher extent, and the use of fluoroquinolones or other broad-spectrum antibiotics was low. The low use of fluoroquinolones is likely to reflect, at least in part, restricted indications under the Australian Pharmaceutical Benefits Scheme. The high use of chloramphenicol, on the other hand, was due to the widespread prescribing of topical chloramphenicol eye preparations for conjunctivitis. Pleasingly, in most cases, the empirical prescribing pattern for UTIs was in line with the national guidelines.24

Routine ordering of microbiological tests is not always practical in the RACF setting. This reflects difficulties in obtaining specimens, the involvement of multiple laboratories servicing these institutions and the lack of timely results that inform prescribing. In addition to difficulties in clinical diagnosis, the lack of clinical cultures also hinders the monitoring of antimicrobial susceptibility trends among this population. Accordingly, alternative approaches such as periodic surveillance of antimicrobial resistance patterns may be more feasible in this setting.

There were several limitations to our study. The results from four RACFs located on a hospital campus may not be generalisable to other RACF populations. However, we noted that most subjects were residents of the facilities, with little traffic of patients from the hospital. The rates of infection remained relatively constant and were comparable to those reported in another longitudinal study in Australia.7 Although the McGeer criteria are the only internationally recognised epidemiological definitions of infection, they may not be completely specific or sensitive for microbiologically confirmed infection. We were not able to analyse the epidemiology of bacterial pathogens, owing to the small number of cultures performed. Recent point prevalence studies have assisted in defining the prevalence of colonisation with antimicrobial-resistant pathogens,8 but data are also required on their contribution to the burden of infection to inform antibiotic prescribing policies.

Work is required in developing policies to prevent infection among RACF residents, to explore the epidemiology of antimicrobial resistance in clinical infections, and in developing antimicrobial stewardship initiatives appropriate to this primary care setting.

2 Proportion control chart showing proportion of infections (episodes/OBD) per month in four Melbourne RACFs, January 2006 to December 2010 (n = 1114)

OBD = occupied bed-days. RACF = residential aged care facility. CL= centre line. UCL= upper control limit (mean + 3 SD). LCL= lower control limit (mean − 3 SD).

4 Commonly prescribed antimicrobials, by site of infection

5 Proportion of episodes with no documentation of collection of a clinical specimen, by type of infection (n = 659)

UTI = urinary tract infection. LRTI = lower respiratory tract infection. URTI = upper respiratory tract infection. SSTI = skin and soft tissue infection.