Infections and antibiotic resistance in nursing homes

Antimicrobial resistance patterns in urinary isolates from nursing home residents. Fifteen years of data reviewed

The antibiotic resistance patterns of gram-negative bacteria isolated from nursing home patients between 1983 and 1997 were analysed. Escherichia coli was the most prevalent isolate (48%) followed by Proteus spp. (26%) and other Enterobacteriaceae (20%). During the study period, the susceptibility of E. coli decreased for co-trimoxazole (79% to 62%), increased for nitrofurantoin (79% to 91%) and remained unchanged for amoxycillin (41%). Susceptibility to norfloxacin, available from 1990, decreased from 87% to 71%. Similar trends were observed when the susceptibilities of all gram-negative urinary pathogens were combined. The changes in susceptibility can probably be attributed to the empirical prescribing practices in the nursing homes studied.

Two nursing home outbreaks of respiratory infection with Legionella sainthelensi

OBJECTIVE

To describe outbreaks of infection caused by Legionella sainthelensi occurring in older residents of two nursing homes and to determine risk factors for the development of infection.

DESIGN

Descriptive epidemiology and a case-control study.

SETTING

Two nursing homes (140 beds and 254 beds in nursing homes A and B, respectively) located in southern Ontario, Canada, experiencing outbreaks of respiratory tract infection in July and August 1994.

SUBJECTS

Case-residents of the two nursing homes who met clinical and laboratory criteria for Legionella infection. Control-residents were defined as those who were in the homes during the outbreaks and were asymptomatic.

MEASUREMENTS

Active surveillance was conducted in both nursing homes to identify symptomatic residents. Residents with fever or respiratory tract symptoms had nasopharyngeal swabs taken for viral antigen detection and culture, urine for Legionella antigen detection, and acute and convalescent serology for viruses, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella. Chest X-rays were performed, and an attempt was made to obtain blood and sputum cultures. Water samples from shower heads, faucets, and air conditioning units were collected for Legionella culture and polymerase chain reaction (PCR) assay. A case-control study was done to assess possible risk factors for legionellosis.

RESULTS

Twenty-nine cases -- 17 in nursing home A; 12 in nursing home B - were identified. Four (14%) case-residents had documented pneumonia and four case-residents died. Univariate analysis revealed that a history of stroke (odds ratio (OR) 2.3 (95% CI, 1.0-5.3)), eating pureed food (OR 4.6 (95% CI, 1.6-12.7)), and having fluids administered with medication (OR 2.5 (95% CI, 1.0-5.9)) were significant risk factors. Cases were less likely to wear dentures (OR .4 (95% CI, .2-.9)) or to eat solid food (OR .3, (95% CI, .1-.6)). Only eating pureed food remained significant in a multivariable analysis (OR 4.6 (95% CI, 1.6-13.0, P = .01)).

CONCLUSION

This report describes outbreaks of legionellosis in two nursing homes, representing the first reported outbreaks of infection caused by Legionella sainthelensi. The association with illness of dietary characteristics indicative of swallowing disorders suggests that aspiration was the most likely mode of infection. The diagnosis of legionellosis should be considered during outbreaks of respiratory infection in nursing homes.

Infection control programs in skilled nursing long-term care facilities: an assessment, 1995

BACKGROUND

In 1989 the Health Care Financing Administration mandated that long-term care facilities (LTCFs) maintain infection control programs; however, few data are available to guide the design of these programs. The purpose of this study was to assess the current status of infection control programs in LTCFs by using methodology adapted from Phase I of the Centers for Disease Control and Prevention Study on the Efficacy of Nosocomial Infection Control.

METHODS

A descriptive study of infection control programs in skilled nursing LTCFs was undertaken in a representative sample of 136 New England skilled nursing LTCFs that have >/=25 beds, with use of a self-report Infection Surveillance and Control Questionnaire.

RESULTS

Nearly all (98%) the LTCFs reported having personnel responsible for infection control, with a median of 8 hours per week spent on infection control activities. Ninety percent of these persons were registered nurses; 52% had formal training in infection control. Twenty-five percent of the respondents reported that their infection control program was either "inactive" or nonexistent in 1988, and 60% rated their programs as either "moderately active" (43%) or "very active" (17%) during that year. By 1994, most LTCFs (67%) rated themselves as "very active," and only 3% as inactive or nonexistent. The mean scores on the questionnaire's surveillance and control indices were 23 (out of a possible 30) and 47 (out of a possible 60), respectively, which indicates medium infection surveillance and control activity. On the basis of the data provided by 72% of the respondents (n = 98), a crude estimate of 13.97 infections per 1000 resident-days was calculated, which is a higher rate than previously reported for LTCFs.

CONCLUSIONS

Findings from the study indicate that it is feasible to use methodology adapted from Phase I of the Centers for Disease Control and Prevention Study on the Efficacy of Nosocomial Infection Control to assess infection control programs in LTCFs; however, further research into the efficacy of nosocomial infection control in skilled nursing LTCFs is needed.

Low-level colonization and infection with ciprofloxacin-resistant gram-negative bacilli in a skilled nursing facility

BACKGROUND

We report a 1-year surveillance study that evaluates colonization and infection with ciprofloxacin-resistant gram-negative bacilli (CR GNB) and the relation to quinolone use and other possible risk factors in a proprietary skilled nursing facility (SNF) with no history of outbreaks.

METHODS

Rectal swabs obtained quarterly were streaked on MacConkey agar with ciprofloxacin discs (5 microg) to screen for CR GNB and later were speciated and the antimicrobial susceptibilities were confirmed by standardized disc-diffusion tests.

RESULTS

The mean prevalence of CR GNB colonization was 2.6% (range 0.9% to 5.3%). The colonization frequency was higher in the last survey than it was in the first survey. CR GNB-colonized strains included Pseudomonas species (21%), but more than half were non-Pseudomonas enterics such as Acinetobacter baumannii (25%), Proteus mirabilis (17%), and Providencia stuartii (13%). None of the patients who had colonization with CR GNB had subsequent infections with the same species. Patients with colonization had more exposure to ciprofloxacin and they were more likely to have been recently admitted from an acute-care hospital and have decubitus ulcers. During the study period, of 336 patients surveyed, 98 (29%) patients developed suspected infections and cultures were done; the infection rate was 4.7 per 1000 patient days. Of these infected patients, 59 (60%) were infected by GNBs; the infection rate was 2.3 per 1000 patient days. Nineteen percent of the GNB infections were treated with a quinolone. (Overall, quinolones constituted about 17% of antibiotic usage in the SNF). Only 3 (5%) of the patients infected with GNB were infected with CR GNB, including Pseudomonas and Providenci a species. The CR GNB infections involved multiple sites, multiple organisms, and long length of stay in the SNF.

CONCLUSIONS

The findings indicate that in this community SNF, a low frequency of colonization or infection with CR GNB existed. Whether continued moderate use of quinolones will lead to increasing levels of CR GNB will require further study.

Validation and application of the pneumonia prognosis index to nursing home residents with pneumonia

OBJECTIVES

To evaluate the predictability of a pneumonia prognosis index in nursing home residents with pneumonia and to use the index to account for acute severity of pneumonia before comparing the short-term outcome of residents with pneumonia treated with intravenous antibiotic therapy in two different settings: an inpatient geriatrics unit and a nursing home

DESIGN

A retrospective chart review of 158 episodes of nursing home-acquired pneumonia treated initially with intravenous antibiotics; 100 episodes were treated in an inpatient acute geriatrics service (AGS), and 58 were treated completely in a nursing home (Nursing Home group)

SETTING

The AGS is a 20-bed unit within a 400-bed, public, university-affiliated hospital. The Nursing Home group consisted of residents of two nonproprietary nursing homes.

PARTICIPANTS

Nursing home residents with radiographically proven pneumonia who had at least one of the following signs/symptoms: cough, fever, purulent sputum, respiratory rate > or = 25 per minute, localized auscultatory findings, or pleuritic pain.

MEASUREMENTS

The pneumonia prognosis index was calculated for each resident at the time of diagnosis of pneumonia; the index has been validated as a predictor of hospital outcome in patients with community-acquired pneumonia and is also considered a measure of acute severity of pneumonia. Status (alive or dead) of each resident at 30 days after diagnosis was the major dependent variable

RESULTS

Mean (+/-SD) duration of antibiotic therapy for the Nursing Home group (10.7+/-4.5 days) was not significantly different from that of the AGS group (9.6+/-3.4 days; P = .26). The pneumonia prognosis index stratified the 158 episodes of pneumonia into low- and high-risk groups for 30-day mortality; the mortality rates in each risk strata were not significantly different from those reported in the original derivation and validation studies of the index. In addition, the distribution of episodes among the risk strata of the index was not significantly different for the two study groups, which was an indication that the two groups were similar in terms of acute severity of pneumonia. Thirty-day mortality was not significantly different between the two groups: AGS, 21% and Nursing Home, 24.1% (P = .66).

CONCLUSION

The pneumonia prognosis index seems to have the same capability for predicting the outcome in nursing home residents with pneumonia as in residents with community-acquired pneumonia. The index is also a measure of acute pneumonia severity. Nursing home residents with pneumonia, even those who are most acutely ill, can be treated successfully with intravenous therapy in the nursing home; their 30-day mortality was no different than that of those with the same acute severity of illness who were admitted to a hospital for treatment.

Multiply-resistant Klebsiella pneumoniae: failure of spread in community-based elderly care facilities

Thirty-eight patients colonized with multiply-resistant, plasmid-mediated, expanded-spectrum beta-lactamase (SHV-2) producing Klebsiella pneumoniae (MRK), were discharged from hospital to 22 nursing or residential homes during a hospital-based outbreak, in the Grampian region of north-east Scotland. MRK colonized the urinary tract in 74%, stool in 58%, respiratory tract in 29% and wounds in 11%. Mean length of colonization was 160 days (range 7-548). Mean length of stay in the homes after aquisition of MRK was 298 days. Compared with a control group of MRK-negative residents, MRK-positive residents had histories of more hospital admissions, underlying disease and complete immobility. Evaluation of these homes showed high standards of care and good facilities. Despite prolonged carriage of MRK by the index cases there was no evidence of spread to the other 886 residents who were screened, and there was evidence of only minor environmental contamination. Given the available evidence, patients colonized with MRK can be accommodated in good-quality nursing and residential homes, on discharge from hospital, with little fear of spread to other residents.

In vitro activity of fleroxacin against multiresistant gram-negative bacilli isolated from patients with nosocomial infections

In order to evaluate the in vitro activity of fleroxacin against nosocomial gram-negative organisms, 263 multiresistant gram-negative bacilli (203 Enterobacteriaceae and 60 non-fermenting gram-negative bacilli) were isolated from adult patients with nosocomial infections. The different patterns of resistance to eight different antimicrobial agents (ampicillin, carbenicillin, piperacillin, cephalothin, cefamandole, ceftazidime, gentamicin and amikacin) were determined by minimum inhibitory concentration (MIC), using the agar dilution method. The most prevalent multiresistant species isolated were Klebsiella pneumoniae (28.9%), Escherichia coli (24%) and Pseudomonas aeruginosa (12.2%). All these bacterial strains showed three to five resistance patterns to at least three different antibiotics. Resistance to ceftazidime was observed in at least one of the resistance patterns of isolated bacteria. The activity of fleroxacin against multiresistant enteric bacteria was excellent; these strains showed a susceptibility of 79-100%. The susceptibility of P. aeruginosa to antipseudomonal agents was low; however, the activity of fleroxacin against these strains was higher than 60% (MIC < or = 2 microg/ ml), broadly comparable with ciprofloxacin. The resistance to fluoroquinolones detected in this study was no cause for alarm (3%). Consequently, fleroxacin maintains a remarkable activity against Enterobacteriaceae and remains highly active against other gram-negative bacilli. Nevertheless, actions directed at preventing or limiting resistance will be crucial to maintain the viability of fluoroquinolones as important therapeutic agents.

Implications of oral infections on systemic diseases in the institutionalized elderly with a special focus on pneumonia

Systemic infection in the elderly patient living in a chronic care setting presents a significant burden to the health care system. The extent to which oral organisms cause systemic infections through hematogenous dissemination in the institutionalized elderly is still unknown. A more likely and common route of systemic infection by oral microorganisms is through aspiration of oropharyngeal fluids containing oral pathogenic microorganisms, which colonize the lower respiratory tract and cause pneumonia. Respiratory pathogens emerge in the dental plaque of elderly patients with very poor oral hygiene and severe periodontal disease. In the chronic care setting, aspiration of oropharyngeal fluids contaminated with these bacteria occurs in patients with diminished host defenses, resulting in bacterial pneumonia. This is also a problem in intensive care units in the hospital setting. In one study, pre-rinsing with a 0.12% chlorhexidine gluconate mouthwash significantly lowered the mortality rate from postsurgical pneumonia in patients undergoing open heart surgery. Selective digestive decontamination, a technique involving the topical application of antimicrobials to reduce the risk of colonization of the respiratory tract, has been used to reduce the incidence of nosocomial pneumonia in the acute care setting of hospitals. This technique has not been employed in the nursing home setting. Whether improving oral hygiene would also lower the risk in either of these settings has not been studied. A number of obstacles must be overcome in designing studies to investigate the relationship between oral infections and lung infections in the institutionalized elderly. Ethical issues must be addressed, and full collaboration of the medical team is required. Future studies should establish whether reducing the risk for pneumonia in the institutionalized elderly is possible through improved oral health.

Hospital-acquired infection in elderly patients

Increasing numbers of elderly people are being treated in hospitals and are at particular risk of acquiring infections. The incidence, risk factors and types of hospital-acquired infection (HAI) in the elderly are reviewed. Special reference is made to urinary tract infections, respiratory tract infections, gastrointestinal infections including Clostridium difficile, bacteraemia, skin and soft tissue infections and infections with antibiotic-resistant organisms.

Risk factors for the spread of antibiotic-resistant bacteria

The emergence of antibiotic resistance is primarily due to excessive and often unnecessary use of antibiotics in humans and animals. Risk factors for the spread of resistant bacteria in hospitals and the community can be summarised as over-crowding, lapses in hygiene or poor infection control practices. Increasing antibiotic resistance in bacteria has been exacerbated by the slow pace in developing newer antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and multiresistant Gram-negative bacteria are spread primarily by direct or indirect person-to-person contact. Independent risk factors for MRSA include the use of broad spectrum antibiotics, the presence of decubitus ulcers and prosthetic devices while those for VRE include prolonged hospitalisation and treatment with glycopeptides or broad spectrum antibiotics. For the spread of resistant Gram-negative bacteria risk factors include urinary catheterisation, excessive use of antibiotics and contamination of humidifiers and nebulisers. The spread of penicillin-resistant pneumococci (PRP) and drug-resistant and multidrug-resistant tuberculosis (MDRTb) is due to airborne transmission. Risk factors for the spread of PRP include overcrowding, tracheostomies and excessive use of penicillins for viral respiratory infections; for MDRTb they include poor compliance, convergence of immunosuppressed patients, delayed diagnosis or treatment, and poor or inadequate ventilation and isolation facilities. Recent developments in the genomic mapping of many bacteria and advances in combinatorial chemistry promise to usher in a new era of antibiotic development. While this may result in our regaining some of the ground lost to resistant bacteria, there will still be a continuing need to minimise the spread of antibiotic resistance through the rational use of antibiotic agents and stringent infection control practice.

Vancomycin-resistant Enterococcus faecium in a long-term care facility

OBJECTIVE

To describe the epidemiology and natural history of colonization with vancomycin-resistant Enterococcus faecium (VREF) in a long-term care facility.

DESIGN

All patients in whom VREF was isolated were followed prospectively, with rectal swab cultures at 2-week intervals, until discharge, death, or clearance of VREF. Clearance was defined as two consecutive negative cultures. In addition, three prevalence surveys were conducted of all patients in residence on one 34-bed intermediate care ward.

SETTING

A 400-bed, long-term care Veterans Affairs facility.

PARTICIPANTS

Thirty-six patients colonized with VREF.

RESULTS

Vancomycin-resistant Enterococcus faecium was identified in 24 of the 36 patients at the time of transfer from an acute care facility. Seventeen patients had concomitant methicillin-resistant Staphylococcus aureus, and seven patients had a recent history of Clostridium difficile-associated diarrhea. VREF in these patients persisted for a median of 67 days after identification. Treatment of VREF colonization with antimicrobials was associated with prolongation of colonization. Serial surveillance of the 34-bed ward found stable rates of colonization, with only three documented instances of VREF acquisition. During 2.5 years of surveillance for infection, a single case of bacteremia occurred in a patient in whom colonization with VREF could not be demonstrated by rectal swab culture. No infections occurred in patients colonized with VREF.

CONCLUSIONS

Long-term care patients have protracted carriage of VREF. Most will improve over time; however, receipt of antimicrobial therapy is associated with prolongation of VREF carriage. The risk of VREF infection is low in this population. When there are appropriate contact precautions, patient to patient transmission occurs at a low rate. These observations can be used to design a practical infection control strategy for long-term care facilities.

Asymptomatic bacteriuria in the elderly

Asymptomatic bacteriuria is frequent in elderly, populations. The major contributing factors are selected physiologic aging changes and comorbid illnesses, which occur with increased frequency in these populations. There is little short-term or long-term adverse outcomes attributable to this high prevalence and incidence of asymptomatic bacteriuria and no evidence for an impact on survival. A number of important questions relating to this problem have yet to be resolved. First, further studies in the noninstitutionalized population are needed to characterize the incidence of asymptomatic infection and its relationship to symptomatic infection. In the institutionalized population, studies to refine the clinical diagnosis of symptomatic urinary infection occurring in a population with such a high prevalence of asymptomatic bacteriuria are needed. In addition, further assessment of the impact of the reservoir of asymptomatic bacteriuria in elderly institutionalized subjects as a contributor to the problem of antimicrobial resistance in the institutionalized population should be a priority.

Methicillin-resistant Staphylococcus aureus in nursing homes. Epidemiology, prevention and management

Infections caused by Staphylococcus aureus are a significant cause of morbidity and mortality in elderly persons in the community, hospitals and chronic care facilities. Methicillin-resistant S. aureus (MRSA) has become an important cause of severe infection in acutely ill patients in hospitals from diverse geographic areas. Whether MRSA has the same potential to spread and cause infection in nursing homes has only recently been explored. In the facilities studied, asymptomatic MRSA carriage has been common, but patients do not appear to have the same risk of acquiring the organism. The risk of MRSA colonisation appears to be associated with increasing debility, the presence of invasive devices or wounds, and increased overall mortality. Most nursing home residents acquire MRSA during a hospital stay, not in the nursing home. Transmission of MRSA between nursing home residents may be less efficient than that seen among hospitalised patients. Once residents acquire MRSA, they remain persistently colonised for months to years. Many different MRSA strains circulate within nursing homes, probably reflecting the strains found in referring hospitals. Fortunately, although MRSA colonisation is relatively common, rates of MRSA infection and attributable mortality appear to be low. However, the presence of MRSA in a facility might lead to fewer treatment options when infections do occur, with more adverse effects and increased costs. The routine use of surveillance cultures and antibacterials in an attempt to permanently eradicate MRSA from nursing home residents has not been successful, and resistance has quickly emerged. More importantly, nursing homes should utilise infection control practices that disrupt transmission by direct contact, thus preventing the potential spread of MRSA. Simple, inexpensive precautions, which emphasise handwashing and the use of gloves and gowns when soiling by patient body fluids is likely, are generally effective. Knowledge of the patient's MRSA colonisation status is not necessary when these universal barrier precautions are applied to the care of all patients. If an increase in the rate of MRSA infections is documented, more intensive infection control measures should be implemented.