218. Persistence Pays: Prolonged Carriage of Plasmid-Borne Broad-Spectrum Β-Lactam Resistant Enterobacteriaceae
Session: Poster Abstract Session: Antimicrobial Resistance: Clinical Studies
Friday, October 21, 2011
Room: Poster Hall B1
Background: Plasmid-borne broad-spectrum β-lactam resistant Enterobacteriaceae (PBLR-E), such as those producing extended-spectrum beta-lactamases (ESBL) or carbapenemases are a growing problem. Currently, there is no accepted method to screen stool for carriage of PBLR-E. We developed a screening method and used it to assess stool carriage in patients with PBLR-E infections.

Methods: Fecal specimens were inoculated into MacConkey broth with cefpodoxime or imipenem. After 24 hours, turbid broth was plated on blood and MacConkey agars. E. coli and Klebsiella spp. isolated from subcultures were screened for resistance using the Vitek GN30 panel. Isolates with reduced susceptibility to ceftriaxone, ceftazidime, or a carbapenem were reported as resistant. Resistance type (ESBL, Amp-C, or carbapenemase) was confirmed phenotypically.

Results: Between 2006 and 2010, 122 patients had PBLR-E identified in a sterile site.  Of these, 42 (34%) had subsequent cultures; 30 had stool screened by the above method and 12 had only urine cultured clinically.

Of the 30 patients with stool cultures (Table), 19 (63%) had PBLR-E identified. The last positive specimen was documented a median of 180 (range 4-1597) days after primary infection. 10 of the patients with stool carriage also had PBLR-E isolated from subsequent sterile sites.  One patient with negative stool had subsequent PBLR-E-positive urine.

Persistent carriage was also documented in 6 of the patients with only repeat urine testing; 5 of these patients had intermittently negative urine cultures by microbiology criteria. These patients all had urological abnormalities.

Resistance phenotypes associated with persistent carriage in stool or sterile sites included 16 ESBL, 8 AmpC, and 1 carbapenemase.

Conclusion: PBLR-E carriage can persist for long periods of time in stool and other sites.

Patients with Stool Screening

                                         

All patients

Fecal Carriage

 

 

 

Yes

n=19

No

 n=11

Median age (IQR)*

6 (2,15)

14 (4,17)

3 (1,6)**

Female

73%

68%

82%

Co-morbidities

 

 

 

Immunocompromise

Urological abnormality

Other

None

60%

17%

10%

13%

63%

21%

5%

13%

55%

9%

18%

18%

Subsequent cultures

 

 

 

Median days of follow-up (range)

Median # samples (range)

238 (4-1597)

3 (1-11)

229 (4-1597)

4 (1-11)

383 (31-1433)

3 (1-6)

* IQR- Interquartile range

** p<0.05


Subject Category: A. Antimicrobial agents and Resistance

Amanda Adler, BA1, Xuan Qin, PhD1,2, Scott Weissman, MD1,3 and Danielle Zerr, MD, MPH3,4, (1)Seattle Children's Research Institute, Seattle, WA, (2)Department of Laboratory Medicine, University of Washington, Seattle, WA, (3)Department of Pediatrics, University of Washington, Seattle, WA, (4)Seattle Children's Hospital Research Institute, Seattle, WA

Disclosures:

A. Adler, None

X. Qin, None

S. Weissman, None

D. Zerr, Sage products, Inc.: Grant Investigator, Research grant
Vioguard, Ltd.: Grant Investigator, Research grant
NIH/NIAID: Grant Investigator, Research grant

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