904. Differences among Age, Location, and Source- stratified Antibiograms of S. aureus, E. coli, and S. pneumoniae
Session: Poster Abstract Session: Antimicrobial Utilization and Resistance in Children
Saturday, October 22, 2011
Room: Poster Hall B1

Background: Pathogen antimicrobial susceptibility rates (antibiograms) are often not stratified by patient characteristics.  We hypothesize that antibiograms stratified by age, location (inpatient vs. outpatient), and specimen type can highlight differences in bacterial drug susceptibility among patient groups. 

Methods: Non-duplicate isolates of E. coli and S. aureus (from 2009), and S. pneumoniae (2008-2009) were identified by the Microbiology Laboratory at Mayo Clinic. Antibiograms stratified by age, location, and specimen source were created for each organism and compared using χ2 or Fisher's exact test.

Results: As shown in table 1, E. coli and S. aureus susceptibility to several drugs was greater in children than adults. In contrast, S. pneumoniae susceptibility was greater in adults than children.   

Table 1: Age stratified susceptibility rates

 

E. coli (n=3425)

S. aureus (n=3046)

S. pneumoniae (n=499)

Ampicillin

Ciprofloxacin

Clindamycin

Oxacillin

Levofloxacin

Penicillin

Erythromycin

Children (<18 y)

 48*

 94*

 82*

78*

90*

 45*

 37*

Adults

55

76

64

65

64

63

58

*p<0.05

Among children, outpatient E. coli isolates were more susceptible than inpatient isolates to cefazolin (96% vs. 82%, p<0.001), ciprofloxacin (96% vs. 85%, p=0.018), and trimethoprim-sulfamethoxazole (77% vs. 59%, p=0.021).  Among adults, outpatient isolates of S. aureus were more susceptible than inpatient isolates to oxacillin (70% vs. 59%, p<0.001), levofloxacin (70% vs. 55%, p<0.001), and clindamycin (70% vs. 56%, p<0.001).

Among children, E. coli urine isolates were more susceptible than blood isolates to ciprofloxacin (96%.vs 56%, p<0.001), and S. aureus respiratory isolates were more susceptible than soft tissue (ST) isolates to oxacillin (86% vs. 70%, p = 0.039).  Among adults, S. aureus urine isolates were less susceptible than ST isolates to oxacillin (52% vs. 66%, p = 0.002) and levofloxacin (33% vs. 63%, p<0.001). ST isolates were more susceptible then respiratory isolates to levofloxacin (68% vs. 54%, p<0.001).

 

Conclusion: E. coli, S. aureus, and S. pneumoniae antibiograms differ by patient age, location, and/or specimen typeAntibiograms stratified by these patient characteristics have potential to enhance appropriate antibiotic selection. 


Subject Category: P. Pediatric and perinatal infections

Sanjeev Swami, MD and Ritu Banerjee, MD, PhD, Division of Pediatric Infectious Diseases, Mayo Clinic, Rochester, MN

Disclosures:

S. Swami, None

R. Banerjee, None

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