Literature Review On Controlling The Transmission Of MRSA

Surveillance Methods for the Control of Nosocomial MRSA

Introduction:

Since its emergence Methicillin-resistant staphylococcus aureus (MRSA) have been recognised as serious nosocomial pathogens that have spread around the world. Thus they have been associated with causing various clinical and economical difficulties (Demir, Coplu and Esen, 2016). As a result a number of healthcare institutions have implemented various cost effective strategies in order to reduce the transmission of MRSA in Hospitals. This review will therefore compare and contrasting different methods carried out by various hospitals around the world in order to regulate and control the transmission of MRSA.

Results:

The study in Taiwan showed that the MRSA infection rate had decreased from 3.58 (baseline period) to 0.42% (period 2) (p<0.05). During the interruption stage the no of MRSA infections increased to 2.21% and by the time the second intervention had been introduced the MRSA infection rate declined to 0.18% (period4). Moreover through the effective use of active surveillance 213 out of 314 patients were screened for MRSA in period 2 and 538 out of 883 patients in period 4. This led to a decline in the positive MRSA rate from 11.3% (period2) to 6.1% (period4) (p=0.028). Overall this led to a 47% reduction in MRSA carriage amongst the patients (Lee et al., 2015).

The study at a Melbourne hospital in Australia involved 2 phases to see the effect of active surveillance. Phase 1 (controlled) compromised of 2183 patients whilst phase 2 (intervention) had 2196 patients .Swab results showed that there was a reduction of MRSA being acquired of 7% per month. This is because the rate of MRSA acquired had declined from 18.5 per 1000 at risk patients in the control phase to 7.9 per 1000 at risk patients in the intervention phase. This resulted in an overall decrease of 7% per month that patients will obtain MRSA (Marshall, Richards and McBryde, 2013)

The study in Tertiary hospital in eastern Switzerland looked at the effects of decolonization strategies on reducing the transmission of MRSA. A 5 day regimen was used that consisted of nasal Mupirocin ointment, Chlorhexidine mouth rinse and a body wash .Out of 78 patients 51 underwent the decolonization method and 27 did not undergo decolonization. Out of 51 patients 30 had completed decolonization successfully and 3 showed spontaneous loss of MRSA. Of the 27 patients that didn’t undergo decolonization treatment 6 had showed spontaneous loss of MRSA, 15 were lost to follow up and of the 15 patients 6 had died (Kohler et al., 2012).

Furthermore the study at a US veteran’s hospital 1,183(4.7%) out of 25,282 patients received the Mupirocin whilst in hospital. The findings were that the patients that had received Mupirocin treatment were less likely to test positive for carrying MRSA when readmitted within 30 days compared to those that did not receive Mupirocin (27.2% vs 55.1% p<0.001) (Nelson, Jones and Rubin, 2012) . 

Discussion:

The study in the Royal Melbourne hospital focused on active surveillance of MRSA in ICU patients by using 2 phases (Control and intervention Phase). Similarly the study in Taiwan used a quasi-experimental, interrupted time series but re-introduced the intervention phase in period 4. This was done in order to evaluate the impact of Transmission of MRSA on ICU patients. Although both these articles used quasi experimental analysis in their study their method of screening, isolation and decolonization within the stages differed. In the Taiwan study during all phase’s decolonization treatment and contact isolation was conducted for all clinical patients. However in the intervention phases (2+4) Active surveillance and decolonization was only implemented for MRSA carriers in the intensive care unit. There is a drop in MRSA carriage which can be seen in period 2-4 due to active surveillance of the positive MRSA cultures. Initially in period 2(intervention stage1) the number of positive MRSA was high at 11.3% and hence therefore by period 4 (reintroduction of intervention Phase) the number had declined to 6.1% within a short time. The overall 47% reduction in MRSA carriage highlights the effect of decolonization and active screening in period 2 which resulted in a reduction in the transmission of MRSA (Lee et al., 2015).  Moreover mathematical models predict that in environments where MRSA is more endemic delivering the combination of active screening and decolonization method will result in a rapid decline in MRSA carriage (Gurieva, Bootsma and Bonten, 2012). This supports the findings of the study in Taiwan as the combination of those strategies led to a decrease in MRSA being acquired among the patients.

On the contrary the study in the Royal Melbourne hospital the methods to measure MRSA transmission differed. Active surveillance was carried out in both phases but isolation & contact precautions was only carried out in the intervention phase. Whereas in the Taiwan study Contact isolation was carried throughout the study but active surveillance was carried out only in the intervention periods. In the control phase the number of MRSA acquired was 18.5 per 1000 at risk patient days and in this phase there was no isolation or contact precautions taken place. In the intervention phase there was 7.9 per 1000 at risk patient days. The decline in the rate of MRSA obtained in the intervention phase is due to contact precautions taken place as the patients wore long -sleeved gowns and were isolated to single rooms (Marshall, Richards and McBryde, 2013). However the study in a Canadian hospital contradicts both these articles that isolating a patient from others will reduce the transmission of MRSA. This study observed whether there was a reduction in hospital acquired infections by isolating residence and comparing them to residences that were placed in normal wards. The outcomes of this study showed that isolating patients did not have an effect of reducing nosocomial infections like MRSA. (Ellison et al., 2014).

Moreover in the RMH study rapid detection of MRSA was carried out using PCR (polymerase chain reactions) assays alongside conventional culture assays. Whereas in the Taiwan study cheap screening plates were used to detect MRSA carriers and the results had taken 2-3 days (Lee et al., 2015).  Rapid detection of MRSA with PCR was used in The RMH study in order to evaluate which patients are needed to be isolated. Furthermore a study in a tertiary care centre in japan assessed the effect of using rapid PCR detection alongside contact precautions. It was concluded that the PCR analysis is useful because it is highly sensitive and doesn’t take long to run which allows for patients to be isolated very quickly. Thus using this as a method for screening patients will lead to faster detection and thus leas to a decline in MRSA transmission (Seki et al., 2015).

The results from the study in the veteran hospital in the US suggest that the patients that were given the antibiotic Mupirocin as a decolonization treatment were unlikely to have MRSA carriage when readmitted to the hospital. The study compromised of 25,282 patients which appeared to be one of the largest studies to see the effect of Mupirocin amongst patients. Of the 25,282 patients 1,183 were administered Mupirocin during their hospitalization. Of those that had received the treatment when readmitted within 30-60 days had a rate of MRSA carriage of 33.9% which is much lower compared to 52.7% of patients that didn’t receive the treatment (Nelson, Jones and Rubin, 2012). Furthermore the study in three Chicago hospitals discovered that despite giving patients different doses of Mupirocin, the treated patients had a lower chance of repeated colonization of MRSA than those who didn’t receive the treatment with Mupirocin (Robicsek et al., 2009). This therefore implies that the use of Mupirocin will inevitably lead to a reduction of MRSA transmission.

The study in the tertiary hospital in eastern Switzerland also looked at the effects of decolonization treatments on MRSA positive patients. Like the US study this study also used Mupirocin as a nasal treatment however the study compromised of a 5 day regimen with various decolonization agents. Of the 51 patients that underwent one decolonization cycle 65% of them had been decolonized successfully. Of the 27 remaining patients that didn’t undergo any decolonization treatment only 6 (22%) showed spontaneous loss of MRSA the remaining 78% were unsuccessful and of that percentage 6 patients had died (Kohler et al., 2012). Considering these results this shows the outcome of this study to be deemed successful. Compared to the 22% of spontaneous loss of MRSA in non-decolonized patients, there was still a higher 65% success rate amongst patients that had undergone the decolonized treatment. Moreover both these studies incorporate the comparison of patients that had undergone the treatment and those that didn’t undergo the treatment, and the inferences that can be made is that decolonization can reduce the rate of MRSA carriage .A limitation in the study in Switzerland is that the number of patients that were analysed was very small (78 patients) compared to the US study where they analysed using a much larger study. This comes about as a drawback in the study as because the smaller the sample size the more likely there is a large standard of error which leads to false positive results and inaccurate estimation (Hackshaw, 2008).

However the underlying issue is that there is a rise in Mupirocin resistance. Mupirocin resistance rapidly occurs when it is primarily used regularly as a method to control MRSA infection and transmission amongst patients. Thus this leads to the need for further research as well as on-going surveillance in order to preserve the efficacy of these agents (Abad, Pulia and Safdar, 2013).

In addition analysing both these articles it seems that decolonization treatments are effective .This is a result of the methods leading to a reduction in the MRSA transmission rate, furthermore the advantage of using decolonizing agents such as chlorohexidine and Mupirocin is that they’re cost effective. The cost for Mupirocin was at US $1.7 per tube for each MRSA carrier and the price of 20 ml of chlorohexidine was US $0.19 (Lee et al., 2015). Since the decolonization treatments chosen in these studies are relatively cheap and their use as a protective effect against MRSA suggests that they are good surveillance methods in order to control the rate of MRSA transmission.

Conclusion:

Using measures like screening, isolation, active surveillance and decolonization has resulted in a decrease in the transmission of nosocomial MRSA. All the articles studied in this literature review have very small p values which was in a range between p<0.001-0.05.This indicates that the studies reviewed were of good statistical standard and therefore they rejected the null hypotheses. Moreover the articles reviewed were very accurate, this is because the findings in the articles correlated with other studies. For e.g. Mathematical models predicted that in areas where endemic MRSA is prevalent delivering a combination of decolonization with active screening will result in a decline in MRSA carriage (Gurieva, Bootsma and Bonten, 2012). Additionally this supported the article in Taiwan as the results indicated that there was an overall 47% reduction in MRSA carriage Hence this supports the findings that the results provided were of accurate values. (Lee et al., 2015).

 To close various articles supported the importance of decolonisation strategies as cost effective and protective measures against the transmission of MRSA. This is because decolonisation plays a direct and indirect role in the control of nosocomial MRSA. When these treatments are implemented amongst all hospital patients it results in an indirect protective effect against non MRSA carriers that happen to be at the hospital (Lee et al., 2015).The use of Mupirocin and chlorohexidine has indeed arisen a lot of queries about their proclaimed resistances and hence further research is needed in order to come up with solutions or alternatives to protect the utility of these treatments.

References: 11

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