Yee-Lean Lee

Nosocomial Infection and Antibiotic Utilization in Geriatric Patients: A Pilot Prospective Surveillance Program in Skilled Nursing Facilities

Prospective surveillance of nosocomial infection was conducted at seven skilled proprietary nursing facilities in Orange County, Calif., USA. The average incidence of facility-acquired infection was 5.2 infections/1,000 patient days. The most common source of infection was urinary tract (47%), followed by respiratory tract (26%) and skin (14%). The four most common pathogens isolated were Proteus spp. (20%), Escherichia coli (17%), Staphylococcus aureus (13%) and Pseudomonas spp. (11%). Trimethoprim-sulfamethoxazole (20%) was the most frequently used antibiotic among all prescriptions, followed by ampicillin (16%) and ciprofloxacin (14%). Among all residents surveyed, 33% received at least one course of antibiotics during the study. Of special significance was the fact that 4 (22%) of the 18 strains of Pseudomonas were gentamicin resistant as were 12 of 80 (15%) of the strains of Enterobacteriaceae. Furthermore, 9 of 29 (31%) strains of Pseudomonas tested were found resistant to norfloxacin as were 15 of 129 (12%) strains of enterobacteriaceae. Susceptibility patterns of the isolated pathogens were similar to those of the acute care hospital. This study indicates that infection continues to be a major problem in the skilled nursing facility and that antibiotic-resistant pathogens will be a challenge for the future.

Surveillance of colonization and infection with Staphylococcus aureus susceptible or resistant to methicillin in a community skilled-nursing facility.

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen in acute care hospitals and long-term care facilities. Few studies have been reported in private skilled nursing facilities (SNFs) not experiencing outbreaks of infections caused by MRSA. METHODS From a 149-bed SNF with no outbreaks, we report a 1-year prospective surveillance study of S. aureus colonization and infection, with focus on S. aureus phenotypes, both methicillin susceptible (MS) and methicillin resistant (MR). Nasal and stool or rectal screening cultures were done on admission, and all patients underwent screening on at least a quarterly basis for 1 year. RESULTS Overall, 35% of patients were colonized at least once with S. aureus, (72% MS, 25% MR, and 3% mixed phenotypes), 94% of the MRSA were ciprofloxacin resistant. Nasal colonization with any S. aureus was more frequent, but 13% of patients had positive results only in rectal specimens. Twenty-one percent of the newly admitted and 15% of continuing patients acquired colonization during their stay in the SNE Colonization was transient or persistent, persisted longer in the nares compared with colonization in rectal specimens, and was more stable for methicillin-susceptible S. aureus. Nine percent of patients had development of infection with S. aureus. There was no indication that MRSA colonization led to more infections than methicillin-susceptible S. aureus. Of the 13 infected patients in whom cultures had previously been obtained, seven (54%) had been colonized by the same phenotype strains. CONCLUSIONS In this private SNF, endemic S. aureus infections occur at a low frequency, reflecting a moderate level of colonization with S. aureus. However, a trend showing gradual increases in frequencies of colonization and infection is of concern and suggests that in this SNF, future intervention could become warranted.

Antibacterial activity of citrate and acetate

OBJECTIVE We evaluated citrate salt, acetate salt, and their combinations for antibacterial activity against a sample of common pathogens. METHODS Bacterial suspensions were added to serial microdilutions of the salts in broth, with final cell concentrations of 10(4-5) colony-forming units per milliliter. After overnight incubation at 35 degrees C, the minimum inhibitory concentration was recorded. Bactericidal activity was screened by quantitative subcultures from the minimum inhibitory concentration dilution. RESULTS Citrate salt was active against gram-positive species and Candida albicans but showed little activity against gram-negative species; acetate salt showed the opposite results. Their combination did not show synergism or antagonism. CONCLUSION It may be feasible to take advantage of the different antibacterial spectra of these two agents and combine them for possible application such as food or medical preservative agents.

Bactericidal activity of citrate against Gram-positive cocci

Aims: Coagulase‐negative staphylococci (CNS) are now important nosocomial pathogens and are usually resistant to multiple antibiotics. Citrate is an alternative antimicrobial product which has been used as a preservative.

Genotyping by restriction endonuclease analysis compared to phenotyping by antibiogram for typing methicillin-resistant Staphylococcus aureus strains colonizing patients in a nursing home.

OBJECTIVES To assist in defining patterns of methicillin-resistant Staphylococcus aureus (MRSA) colonization in a skilled nursing facility (SNF), we compared genotyping by field-inversion gel electrophoresis (FIGE) restriction endonuclease digestion analysis (REA) with phenotyping by antibiogram for defining strain relatedness among MRSA isolates from SNF patients. DESIGN Prospective screening culture surveillance for MRSA among patients in a community SNF. METHODS Nares and stool swab cultures were obtained from newly admitted patients and from all patients quarterly. MRSA were isolated by oxacillin screening agar. Antibiograms were determined by the disk-diffusion method, and genotyping was by FIGE REA. RESULTS It was shown that, among isolates with the same genotypes, many had different antibiograms; among isolates with the same antibiograms, many had different genotypes; and the discriminatory indices for isolates of MRSA by FIGE REA and by antibiogram were 0.56 and 0.78, respectively. CONCLUSION Our study demonstrated that, in patients from one SNF, genotyping by FIGE REA identified two prevalent REA DNA types, but with variability of antibiogram patterns within each DNA type; the antibiogram also identified prevalent patterns with variability of REA DNA type within each antibiogram pattern. The discriminatory index of antibiograms alone, or of genotypes alone as determined by FIGE REA, was poor for strains of MRSA isolated from the SNF patients in our study.