2172. Prevalence and characteristics of qacA/B-positive methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection isolates in a tertiary hospital.
Session: Poster Abstract Session: HAI: MRSA, MSSA, and Other Gram Positives
Saturday, October 7, 2017
Room: Poster Hall CD

Background: The increasing use of chlorhexidine (CHG) for MRSA decolonization has raised concerns about the emergence of resistance or tolerance to these agents.

Methods: We evaluated the frequency and characteristics of qacA/B chlorhexidine tolerance genes among MRSA bloodstream infection (BSI) isolates at a tertiary hospital in Korea. MRSA BSI isolates collected from 2011 to 2016 was examined for carriage of qacA/B and smr genes and high-level mupirocin resistance. Staphylococcal cassette chromosome mec (SCCmec) and spa typing was also performed. 

Results: Of the 203 MRSA BSI isolates, 57 (28.1%) were positive for qacA/B, 6 (3.0%) were positive for smr, and 15 (7.4%) were mupirocin resistant. Table 1 shows characteristics of qacA/B-positive vs. qacA/B-negative MRSA BSI. Patients with qacA/B-positive isolates were more often diagnosed with nosocomial BSI and catheter related BSI, but were less often diagnosed with bone and soft tissue infections. The qacA/B-positive isolates were more often resistant to mupirocin, clindamycin, and ciprofloxacin and more often had a CHG MIC of >= 4mg/L. The qacA/B-positive isolates were more likely to belong to SCCmec II or III (84.2% vs. 38.5%, P < 0.001), which are common healthcare-associated (HA) MRSA strains in Korea. Most common spa types in qacA/B positive isolates were t2460 (64.9%) and t9353 (14.0%).

Conclusion: The qacA/B carriage among MRSA BSI isolates are not uncommon in this study and showed the features of HA-MRSA BSI.

Table 1. Characteristics of qacA/B-positive vs. qacA/B-negative MRSA BSI.

Characteristics

qacA/B (+)

(n=57)

qacA/B (-)

(n=146)

P

Age, median years(IQR)

72 (60-84)

69 (56-75)

0.062

Nosocomial BSI

44 (77.2)

61 (41.8)

< 0.001

Catheter related BSI

35 (61.4)

41 (28.1)

< 0.001

Primary BSI

14 (24.6)

38 (26.0)

0.999

Bone and soft tissue infections

4 (10.8)

33 (22.6)

0.009

Pneumonia

2 (3,5)

12 (8.2)

0.358

Other infections

2 (3.5)

13 (8.9)

0.242

Clindamycin resistant

56 (98.2)

96 (65.8)

<0.001

Ciprofloxacin resistant

56 (98.2)

56 (38.4)

<0.001

Vancomycin MIC >= 2mg/L

17 (29.8)

26 (17.8)

0.084

Chlorhexidine MIC >= 4mg/L

54 (94.7)

50 (34.2)

<0.001

SCCmec II

37 (64.9)

39 (27.3)

<0.001

SCCmec III

11 (19.3)

16 (11.2)

0.168

SCCmec IV

9 (15.8)

88 (61.5)

<0.001

30 day mortality

14 (24.6)

35 (25.0)

0.999

Data are no. (%) of cases

Oh-Hyun Cho, MD, Department of Internal Medicine, Gyeongsang National University Changwon Hospital, Changwon, Korea, Republic of (South), Ki-Ho Park, MD, Division of Infectious Diseases, Department of Internal Medicine, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Korea, Republic of (South), Song Mi Moon, M.D., Ph.D., Infectious Disease, Korean Armed Forces Capital Hospital, Seongnam, Korea, Republic of (South) and In-Gyu Bae, MD, Gyeongsang National University Hospital, Jinju, Korea, Republic of (South)

Disclosures:

O. H. Cho, None

K. H. Park, None

S. M. Moon, None

I. G. Bae, None

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