Infection Control & Hospital Epidemiology
Table 1. Risk Factors for Shedding of Methicillin-Resistant Staphylococcus aureus (MRSA) during Procedures by MRSA Carriers with Nasal and/or Wound Carriage
No
Characteristic Age, mean y
Limited mobilityb Wounds with MRSA Nares culture positive Indwelling devicesc
Antibiotics used to treat MRSAd
Other antibiotics Diarrhea
Chlorhexidine bathing
Shedding (n=29), No. (%)a
66
24 (83) 17 (59) 26 (90) 19 (66) 10 (35)
9 (31) 6 (21) 1 (3)
Shedding (n=23), No. (%)a
67
19 (83) 6 (26)
18 (78) 15 (65) 6 (26)
12 (52) 5 (22) 1 (4)
P
Value .62 1
.04 .46 1
.73
.21 1 1
Note. MRSA, methicillin-resistant Staphylococcus aureus. aUnless otherwise indicated. bMobility score is a subcategory of the Braden score for prediction of pressure ulcer risk with 1–3 indicating limited mobility: 1=completely immobile, 2=very limited, 3=slightly limited,
4 = no limitation. cCentral venous catheters and urinary catheters. dVancomycin, linezolid,daptomycin, ceftaroline, doxycycline,andtrimethoprim/sulfamethoxazole.
331
with shedding during >50% of procedures had wounds and indwelling devices; for the 12 carriers with shedding during <50% of procedures, 9 (75%) had wounds and 10 (83%) had indwelling devices.
Discussion
In a cohort of MRSA carriers with positive nares and/or wound cultures, we have demonstrated that environmental shedding of MRSA occurred frequently during a wide range of medical proce- dures and patient care activities. Shedding occurred more often at sites ≤0.9 m than at sites >0.9 m from patients and was also common on sites touched by personnel and on portable equipment used for procedures. Most isolates detected in the environment and on equipment after procedures were genetically related to concur- rent nasal isolates. The 2 most common spa types (t008 and t002) recovered are the predominant spa types in the United States.14 Our findings have important implications for prevention of MRSA transmission. It is plausible that measures such as chlorhexidine bathing and
contact with patients (ie, 1 ultrasound device, 2 pieces of physical therapy equipment, and 5 pieces of equipment used for patient transfer) and 17 did not; all 17 of the devices that became conta- minated without touching patients were touched by the hands of personnel during the procedures. A total of 88 MRSA isolates from 40 patients were subjected to
spa typing. The nares isolates from 33 patients included 12 known spa types and 2 isolates that did not match previously identified spa types. The most common spa types were t008 (7 patients), t002 (6 patients), and t037 (4 patients). For 18 patients with con- current nasal and environmental MRSA isolates subjected to spa typing, 16 (89%) had 1 or more environmental isolates with the same spa type as the nasal isolate. For 9 patients with concurrent nasal and skin MRSA isolates, 9 (100%) had skin isolates with the same spa type as the nasal isolate. For 5 patients with concurrent nasal and portable equipment MRSA isolates, 3 (60%) had equip- ment isolates with the same spa type as the nasal isolate. Finally, for 5 patients with concurrent nasal and wound MRSA isolates, 4 patients (80%) had wound isolates with the same spa type as the nasal isolate. Table 1 shows the results of the patient-level bivariate analysis
of risk factors associated with environmental shedding of MRSA during procedures. The only factor that was significantly associ- ated with shedding (defined as 1 or more positive environmental culture during 1 or more procedures) was the presence of a wound that was culture-positive for MRSA. For carriers with positive nasal cultures, there was no significant difference in the burden of nasal MRSAfor those with versus without shedding (2.4 vs 1.8 log10CFU per swab; P = .72). Of the 29 MRSA carriers with shedding of MRSA to the envi-
ronment during 1 ormore procedures, 18 (62%) were assessed dur- ing 3 or more procedures. Of these 18 MRSA carriers, 6 (33%) had positive environmental cultures for MRSA during >50% of proce- dures. The characteristics of the subjects with shedding during >50% and <50% of procedures were similar. All 6 of the carriers
covering of open wounds might be useful as “source control” to reduce shedding of MRSA during procedures.15 In the current study, only 4% of the MRSA carriers included in the assessment of shedding during procedures were receiving chlorhexidine bath- ing. Because MRSA carriers frequently have contamination on their clothing and hands, providing daily clothing changes and patient hand hygiene are other simple approaches that might be useful as components of a bundle of practices to reduce the risk for shedding.16–18 Our results also reinforce recommendations from current
guidelines that equipment should be cleaned between patients, par- ticularly when used in isolation rooms.19 Recent studies suggest that cleaning of portable equipment is often suboptimal despite written protocols.20,21 Thus, some method of monitoring equip- ment cleaning practices is needed to ensure compliance. Our results also suggest that it might be beneficial to clean surfaces after procedures, focusing on areas contacted by personnel or equip- ment. One practical approach might be to develop peri-procedure protocols based on our findings and on evidence that personnel frequently become contaminated during procedures.10 Such peri-procedure protocols might include both routine cleaning of portable equipment and surfaces contacted during procedures and wearing of personal protective equipment for high-risk proce- dures. Increasing the frequency of cleaning by providing daily dis- infection of high-touch surfaces in MRSA isolation rooms has previously been shown to reduce acquisition of MRSA on hands of personnel.22 If peri-procedure cleaning protocols are recom- mended, it would be essential to ensure that personnel have easy access to disinfectant products (eg, cannisters of wipes located in patient rooms or directly attached to portable equipment). It is generally accepted that the risk for shedding of pathogens
may vary widely among patients and a subset of colonized or infected individuals may be classified as super-spreaders.23–25 For MRSA, previous studies have identified increased nasal density, indwelling devices, and decreasedmobility as patient characteristics associated with shedding.2–9 It is also plausible that shedding varies with different patient care activities. Pineles et al10 identified wound care as one of several patient care activities associated with MRSA contamination of cover gowns and gloves during care of LTCF res- idents withMRSAcolonization. In the current study, the presence of a wound with MRSA was associated with shedding during proce- dures and care activities by bivariate analysis. However, shedding
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132
