Yiel-Hae Seo

Reduced use of third-generation cephalosporins decreases the acquisition of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae

OBJECTIVES To identify risk factors for the respiratory acquisition of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae among patients admitted to a neurosurgical intensive care unit (NSICU) and to modify them without changing general infection control measures. DESIGN Nested case-control and intervention study. SETTING A 1,200-bed, tertiary-care teaching hospital with a 17-bed NSICU. METHODS Sputa of all patients admitted to the NSICU were cultured weekly during the study. From October 2002 through February 2003, 29 case-patients from whose sputum ESBL-producing K. pneumoniae was isolated were detected and 59 controls-patients were randomly selected among patients without any positive isolate of ESBL-producing K. pneumoniae. After analyzing the risk factors, we intervened to modify them and compared the acquisition rate of ESBL-producing K. pneumoniae before (October 2002 to February 2003) and after (April to August 2003) the intervention. RESULTS Multivariate analysis showed that prior exposure to third-generation cephalosporins (TGCs) (OR, 6.0; CI95, 1.9 to 18.6; P = .002) was an independent risk factor of ESBL-producing K. pneumoniae acquisition. The neurosurgical team was notified of the result, and the infectious diseases specialist visited the NSICU three times a week to regulate TGC use during the intervention period. Patients admitted before the intervention were older than patients admitted after. The respiratory acquisition of ESBL-producing K. pneumoniae per 1,000 patient-days (13.5 [CI95, 8.9 to 18.1] vs 2.7 [CI95, 0.9 to 4.6]) and the antimicrobial use density of TGCs (38.2 +/- 5.0 vs 17.3 +/- 2.6; P < .001) decreased significantly after the intervention. CONCLUSION Prior exposure to TGCs was an independent risk factor for the respiratory acquisition of ESBL-producing K. pneumoniae, and less use of TGCs was associated with a decrease in acquisition.

Brain Abscess Due to Gemella haemolysans

ABSTRACT We present a case of brain abscess due to Gemella haemolysans and Bacteroides species in a 60-year-old-immunocompetent man who underwent dental procedures. The patient completely recovered following intravenous therapy with ampicillin and metronidazole for 6 weeks.

Comparison of Trends of Resistance Rates over 3 Years Calculated from Results for All Isolates and for the First Isolate of a Given Species from a Patient

ABSTRACT We compared trends of annual resistance rates calculated from results for all isolates and for the first isolate of Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii per patient over a 3-year period from 2001 through 2003. Antimicrobial susceptibility results of inpatients were extracted from a computerized database. Annual resistance rates of a species were calculated by two methods: (i) from results for all isolates, even those from patients with multiple isolates in a given year and (ii) from results for the first isolate from a patient in a given year, regardless of susceptibility profile or specimen type. Rates of methicillin-resistant S. aureus (MRSA) did not differ among all isolates (79.9, 78.8 and 79.6%; P = 0.86), but decreased for the first isolate per patient (70.2, 65.7, and 64.1%; P = 0.006) over time. Annual duplication rates of methicillin-susceptible S. aureus (MSSA) decreased (39.6, 37.6, and 31.7%; P = 0.01), but those of MRSA increased significantly (64.3, 67.8, and 68.9%; P = 0.004). Rates of cefotaxime-resistant K. pneumoniae did not differ over time by either method, and rates of imipenem-resistant A. baumannii decreased over time by both methods. Duplication rates did not differ for either susceptible or resistant isolates of K. pneumoniae and A. baumannii. The trends in MRSA rate differed by the two methods because of the different proportion of duplicate isolates per year. MRSA rates might be increasingly overestimated for all isolates. These results suggest that the method of calculating results for the first isolate per patient may remove the effect of duplication, allowing the simple and unambiguous analysis of cumulative susceptibility rates.

A Case of Primary Infective Endocarditis Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus in a Healthy Individual and Colonization in the Family

Primary community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) endocarditis has rarely been reported in healthy individuals without risk factors, such as skin and soft tissue infections, and intravenous drug abuse. We describe a case of infective endocarditis by CA-MRSA (ST72-PVL negative-SCCmec IVA) in previously healthy individuals with no underlying medical condition and CA-MRSA colonization in the family.

Pseudooutbreak of Stenotrophomonas maltophilia bacteremia in a general ward

BACKGROUND Stenotrophomonas maltophilia is a significant nosocomial pathogen and is commonly isolated in the hospital environment. We investigated the risk factors for a bloodstream pseudooutbreak of S maltophilia in a general ward. METHODS On November 24 and 25, 2005, 7 patients without evidence of sepsis were reported as positive for blood culture with S maltophilia from blood samples collected on November 21 and 22, 2005. We conducted an epidemiologic investigation and a case-control study of this pseudooutbreak. RESULTS All 7 S maltophilia showed the same antibiogram and an indistinguishable pattern on pulsed-field gel electrophoresis. The observational study revealed multiple lapses in infection control, including multiple use of a single bottle of saline for dilution of antibiotics. A case-control study showed that one health care worker, who collected blood samples from 6 of 7 patients, was a significant risk factor for the pseudooutbreak of S maltophilia (P < .05). CONCLUSION We suggest that the combination of multiple lapses in infection control and the blood-collecting behavior of a health care worker might be the cause of the pseudooutbreak of S maltophilia.