[Impact of nasal colonization by methicillin-resistant Staphylococcus aureus among geriatric intermediate care facility patients]

[Systematic screening for methicillin-resistant Staphylococcus aureus (MRSA) in the nasal cavities of patients hospitalized in the dermatology departments of the Saint-Louis Hospital]

OBJECTIVES

In a bid to combat methicillin-resistant Staphylococcus aureus (MRSA) more efficiently in our department, we performed a study to 1) clarify the MRSA carriage rate in patients hospitalized in the department; 2) evaluate the rate of MRSA acquisition during hospitalization; 3) describe the MRSA carrier profile; 4) study the morbidity and mortality associated with MRSA.

PATIENTS AND METHODS

We conducted a three-month prospective study in all patients hospitalized for more than 24hours in the dermatology department of the Saint-Louis Hospital. Nasal swab cultures were performed on the day of admission, once a week thereafter and on the day of discharge. Clinical and epidemiological data were individually reviewed by means of a standardized questionnaire.

RESULTS

In 310 patients, the prevalence of nasal MRSA carriage at admission was 6.5%. During hospitalization, 1.9% of our patients became colonized with MRSA. MRSA carriers were significantly older than non-carriers and had been hospitalized more frequently over the previous 12 months, principally in intensive care or in intermediate or long-term care facilities, and erosive and/or ulcerated dermatitis was more common in this population. Of the 27 patients colonized with MRSA, only three had MRSA infections, and these were successfully treated with antibiotics.

DISCUSSION

The observed rate of MRSA carriage was close to that seen in intensive care units (7%). While systematic screening for MRSA in patients with erosive and/or ulcerated dermatitis would allow detection of twice as many cases of MRSA than the usual screening recommendations, this would be associated with little tangible benefit and high costs, and we therefore decided not to change the usual MRSA screening politic in our dermatology department.

The frequency of nasal carriage in chronic urticaria patients

OBJECTIVE

Chronic urticaria is characterized by oedema of the skin and mucous membranes. Although many agents have been implicated, aetiology is unknown in 70 to 75% of patients. Infections and foci of chronic infections are most commonly held responsible for chronic urticaria. In this study, the frequency of nasal carriage as the occult focus of infection and sensitivity to antimicrobials are explored in patients with chronic urticaria.

MATERIAL AND METHOD

Ninety-four patients with chronic urticaria and 30 controls participated in the study, which was carried out at the Ege university medical faculty, department of dermatology between January 2004 and January 2005. Nasal swab specimens were taken from the patients and controls and incubated at 37 degrees C degrees for 48 h, and inoculated on standard bacterial medium (blood agar). Antimicrobial susceptibility of a growth from isolates of the nasal swab specimens was conducted. Data were analysed statistically using chi-square and Mann-Whitney U-tests.

RESULTS

Ninety-four patients with chronic urticaria (72.3% female and 27.7% male) and 30 controls (63.3% female and 36.7% male) comprised the study group. Mean age of the patients and controls were 42.6 and 33.8 years, respectively. Staphylococcus aureus was detected in swab specimens from the nasal cavity in 50 of the 94 patients (53.2%) with chronic urticaria and four of the 30 controls (13.3%). Testing revealed that the most susceptible antibiotics were cefaclor, ceftriaxone, amoxycillin-clavulanic acid, amikacin, netilmicin, and fucidic acid.

CONCLUSION

Growth on cultures prepared from nasal swab specimens of chronic urticaria patients was statistically higher than the control group. We detected resistance to growth against mupirocin, an antibiotic frequently used in nasal carriage. High nasal carriage of Staphylococcus aureus in patients with chronic urticaria compared to controls suggests that nasal carriage as a focus of infection should be kept in mind as aetiology.

Community-onset healthcare-associated MRSA bacteraemia in a district general hospital

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is associated with significant mortality and morbidity. This retrospective study involved 76 episodes over four years in a district general hospital in the UK. Twenty-eight of these episodes (36.8%) occurred within 72 h of admission. All of these, however, had risk factors for MRSA acquisition and were classified as healthcare-associated bacteraemias. The mortality rates (all causes) at seven days and three months were 31.5% and 53.4%, respectively. Ten patients died before targeted therapy could be commenced. All patients in the study had multiple comorbidities, and pneumonia was a common diagnosis. Previous antibiotics, increased age, admission on surgical wards/intensive care units, and the presence of central venous cannulae and urinary catheters were risk factors for infection. In 48.7% of episodes, patients were not known to be colonized with MRSA prior to their bacteraemia. Empirical targeted therapy should be given to patients with risk factors for MRSA and staphylococci in blood cultures pending susceptibility results. Increased use of screening may also be required to reduce transmission and increase the likelihood of appropriate empirical antimicrobial therapy. Eradication of MRSA from carriers in the community should be considered to reduce the number of community-onset healthcare-associated bacteraemias.