Effect of antibiotics on the bacterial load of meticillin-resistant Staphylococcus aureus colonisation in anterior nares.
J Hosp Infect
; 70(1): 27-34, 2008 Sep.
Article
in En
| MEDLINE
| ID: mdl-18632184
ABSTRACT
Prevalence of hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) infection or colonisation has been associated with antimicrobial consumption. The impact of antibiotic treatment on nasal colonisation is unknown. We conducted a three-month prospective study of 116 patients with extranasal MRSA infection or colonisation, whose nasal MRSA bacterial loads were determined during and after various antibiotic courses over a period of three weeks. Environmental swabs were also taken from the near patient environment. Concomitant nasal MRSA carriage was observed in 76.7% of extranasal MRSA-colonised or -infected patients. The median nasal MRSA bacterial load increased significantly from 2.78 (range 0-6.15) to 5.30 (range 2.90-8.41) log(10) cfu per swab (cfu/swab) (P<0.001) over 21 days during beta-lactam therapy. It also increased from 0 (range 0-4.00) to 4.30 (range 0-7.46) log(10)cfu/swab (P=0.039) over 14 days during fluoroquinolone therapy. Median bacterial loads were significantly higher for beta-lactam- and fluoroquinolone-treated patients on day 7 [4.78, range 0-7.30], day 14 [4.30, range 0-7.60] and day 21 [5.30, range 2.90-8.41] than controls not receiving antibiotics (P<0.05). These loads then decreased by 2-5log(10)cfu/swab 2 weeks after discontinuation of antibiotics. The environment of patients receiving beta-lactam agents (relative risk 3.55; 95% confidence interval 1.30-9.62; P=0.018) or fluoroquinolones (4.32; 1.52-12.31; P=0.008) demonstrated more MRSA contamination than the environment around control patients (0.79; 0.67-0.93; P=0.002). Patients on beta-lactam or fluoroquinolone therapy have increased incidence of MRSA colonisation and higher nasal bacterial loads, and appear to spread their MRSA into the near patient environment.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Staphylococcus aureus
/
Carrier State
/
Nose
/
Methicillin Resistance
/
Anti-Bacterial Agents
Type of study:
Etiology_studies
/
Observational_studies
Limits:
Adult
/
Aged
/
Aged80
/
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
J Hosp Infect
Year:
2008
Document type:
Article
Affiliation country:
China