Community MRSA preys on the poor and deprived

deprivation mrsa

As you can probably tell from the title, this post comes with a warning: it presents some rather “un-PC” data, but I’ll do my best to deliver it calmly and dispassionately! My old research team from KCL have just published a paper in PLOS Medicine on the association between social and material deprivation, and MRSA.

I’ve been interested in the dynamic between hospital-associated (HA) and community-associated (CA) MRSA for years (not least because it was the subject of my PhD thesis). I wrote a review several years ago on how community MRSA should be seen as a genotypic phenomenon with epidemiological implications. Using this framework, it is possible to get your head around CA strains of MRSA beginning to cause hospital-acquired infections. The aim of this study was to use a large collection of MRSA from across several regions of London to explore the transmission dynamics and epidemiological associations of HA and CA types of MRSA.

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What is the fitness cost of mupirocin resistance?

Jon posted a blog last week on mupirocin resistance in MRSA. This week, guest blogger Dr Gwen Knight (bio below) writes about a companion paper also published in the Journal of Antimicrobial Chemotherapy, which models mupirocin resistance…

It is a truth universally acknowledged, that acquiring most mechanisms of drug resistance incurs a fitness cost to the host bacterium. Determining the size of this cost and the impact that this cost will have on the spread of drug resistance is difficult. Is a 10% reduction in growth rate in the laboratory enough to stop resistance spreading in a hospital?

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Mupirocin use drives mupirocin resistance…or does it?

mupirocin

I’ve blogged before that mupirocin resistance is an inevitable consequence of mupirocin use. Whilst I still think that this is true, my old colleagues from GSTT / KCL have just published an article suggesting that mupirocin resistance in MRSA has more to do with clonal variation than with mupirocin use.

The study is part of an ambitious project to sequence the genome of around 1000 MRSA isolates from across Central and South-East London (Guy’s and St. Thomas’, King’s, and Lewisham). Each isolate was then tested for phenotypic high (HMR) and low (LMR) mupirocin resistance, the genome was scoured for the genetic determinants known to be associated with mupirocin resistance, and clone was derived from the genome sequence. Risk factors for both HMR and LMR were then explored.

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How can we stop nursing homes nurturing MRSA?

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There is an emerging feeling that we need to start spreading the focus of infection prevention and control beyond acute hospitals. There has always been a sense that standards of infection control outside of acute settings are, shall we say, “different” to acute hospitals (aka non-existent) so it’s great to see a study of an infection control intervention in nursing homes.

The study was a cluster randomised controlled trial of MRSA screening, decolonisation and enhanced environmental disinfection vs. standard precautions in 104 of 157 nursing homes in a Swiss region. The authors chose a rather unusual, pragmatic endpoint of the prevalence of MRSA colonisation after 12 months.

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MRSA in Denmark

MRSA

(from Statens Serum Institut, EPI-News, N023-2015)

‘The number of hospital­-acquired cases observed in 2014 increased to 95 from 52 cases in 2013, but still comprise only a limited share of the total number of cases (3%). The number of MRSA cases of the CC398 type, which is closely associated with pigs, increased substantially from 643 cases in 2013 to 1,276 cases in 2014 and comprised 43% of the total number of cases. Community­-acquired MRSA, i.e. in persons with no known contact to pigs, hospitals or nursing homes, comprised 946 cases in 2014, compared with 821 cases in 2013. In 478 of these cases (51%), there was known exposure to a person with MRSA, most frequently a member of the household (92%). In 56 cases, MRSA was isolated from blood, corresponding to 2.9% of all S. aureus bacteraemia cases, which is a substantial increase with respect to recent years, but the figure remains low compared with other European countries.’

And here I stop citing the report. For those interested in the complete report, please follow the link: MRSA Denmark.

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The English MRSA Miracle

If, in 2004, I’d told an MRSA expert that there would be around only 200 MRSA bloodstream infections (BSI) per quarter in England throughout 2014 they’d have laughed out loud. This is because, back in 2004, there were sometimes more than 100 MRSA BSI per month in some London hospitals (and around 2000 per quarter nationally), combined with a general perception that only around 30% of MRSA BSI are preventable. How wrong we were.

The reduction of MRSA BSI in England has been dramatic, with a reduction in the region of 90% achieved over a 5 year period. I was asked to speak on “The English MRSA Miracle” at a conference in Portugal today, so thought I’d share my thoughts. You can download my slides here.

It’s difficult to pin down exactly what is behind the ‘MRSA Miracle’ since quite a number of interventions occurred at more or less the same time (Figure 1):

Figure 1: National interventions aimed at reducing MRSA BSI.mrsa bacteraemia whats made the differecnce

Some have postulated that the national cleanyourhands campaign is responsible for the dramatic success. Indeed, there is a BMJ study that makes this case, showing that the national significant increase in the use of soap and water and alcohol gel correlated with the reduction in MRSA BSI. However, I contend that this can’t be the case because what has happened to the rate of MSSA and E. coli BSI over the same period? Nothing – no reduction whatsoever. If increases in hand hygiene compliance really do explain the reduction in MRSA BSI, then they should also reduce the rate of MSSA BSI (unless the increase in hand hygiene compliance only occurred after caring for MRSA patients, which seems unlikely).

There’s a more important epidemiological point here though. High-school tells us to change one variable at a time in science experiments. And yet in this case multiple variables were modified, so it’s not good science to try to pin the reduction to a single intervention, no matter how strong the correlation. (I should add that the authors of the BMJ study do qualify their findings to a degree: ‘National interventions for infection control undertaken in the context of a high profile political drive can reduce selected healthcare associated infections.’)

There has been much discussion about whether we should be investing in a universal or targeted approach to infection control. The failure of improved hand hygiene to make any impact on MSSA BSI suggests that targeted interventions are behind the reduction in MRSA. So what targeted interventions were implemented that may have contributed to the decline? MRSA reduction targets were introduced in 2004, a series of ‘high-impact interventions’ focused mainly on good line care in 2006 and revised national guidelines in 2006 (including targeted screening, isolation and decolonization) all contributed to a surge of interested infection control. Infection control teams doubled in size. Infection control training became part of mandatory induction programmes. And hospital chief executives began personally telephoning infection control to check “how many MRSA BSIs” they had left.

The ‘English MRSA Miracle’ has not been matched in most parts of Europe, except in France, which has had a rather more steady ‘MRSA Miracle’ of its own (Figure 2).

Figure 2: Rate of methicillin-resistance in invasive S. aureus infections, from EARS-Net.MRSA europe rates 

What is behind the failure of most European countries in controlling MRSA? The barriers are multifactorial, but include high levels of antibiotic use, a lack of single rooms for isolating patients, infection control staffing, and, of course, crippling national debt (Figure 3).

Figure 3: Barriers to infection prevention and control in Europe.barriers to IC Europe

If the English MRSA Miracle is to be replicated across Europe, it will take concerted national initiatives to raise the profile of infection control, combined with considerable investment, which is challenging in these times of austerity.

A postcard from Portugal: “Some days we don’t have any needles on the ICU”

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Most of us know that Portugal is facing a dual threat: high rates of antibiotic-resistant bacteria and financial difficulties. This results in a vicious cycle: there’s no money to address antibiotic resistance, so transmission continues unabated and the antibiotic resistance problem gets worse. You can understand the dilemma from the hospital administrators’ viewpoint: I met an intensivist who confessed that “some days we don’t have any needles”. In this situation, is it better to buy some needles or invest in another infection preventionist?

I recently attended a national infection control meeting in Portugal, where I participated in a forum on “International experiences with HCAI”. You can download my slides here.

MRSA first emerged as a problem in the 1980s in Europe. It became a major problem in many European countries in the 1990s and 2000s so that recent data from ECDC shows high rates of meticillin resistance in S. aureus invasive isolates, especially in some southern European countries; the contrast between the rate of MRSA in the UK and Portugal is stark. In the early 2000s, the rate of MRSA was higher in the UK than in Portugal whereas now, it is much lower in the UK (Figure 1).

Figure 1: Rates of meticillin-resistance in invasive S. aureus in the UK and Portugal. Data from EARS-Net.mrsa uk vs portugal earsnet

Greece, Italy and Portugal are especially affected, with 25 to >50% of invasive S. aureus isolates resistant to methicillin. In the UK, a national strategy has yielded a dramatic reduction in the number of MRSA bloodstream isolates reported to the government in a mandatory reporting scheme (Figure 2).

Figure 2: Dramatic reductions in MRSA bacteraemia in England. But what has made the difference? mrsa bacteraemia whats made the differecnce

Since the national intervention in England was multifactorial, it is not clear what made the most impact, and it seems likely that more than one intervention contributed to the decline. Interventions included increased attention to intravenous line care, cleaning and disinfection of the environment, improved diagnostics (including the introduction of chromeagar and rapid PCR) and a national hand hygiene campaign. Perhaps the single most important intervention was the introduction of MRSA reduction targets, which were very controversial at the time, but put the issue of MRSA higher on the priority list for the hospital administration.

And this issue is not restricted to MRSA. In fact, the threat of the resistant Gram-negatives is even greater than MRSA in many ways. Carbapenem-resistant Enterobacteriaceae are rare currently in Portugal, accounting for 1-5% of invasive K. pneumoniae isolates. However, you get the feeling that it’s only a matter of time: carbapenem-resistant Acinetobacter baumannii are now endemic on many Portugese ICUs, and carbapenem use in Portugal is some of the highest in Europe, with >45% of patients on an antibiotic and >5% of patients on a carbapenem according to the ECDC point prevalence survey. Indeed, there has been a disturbing increase in multidrug-resistant K. pneumoniae in Portugal in recent years (Figure 3).

Figure 3: Disturbing emergence of multidrug-resistant Klebsiella pneumoniae in Portugal. Data from EARS-Net.

mdr kleb uk vs portugal ears net

The reason for these differences between the UK and Portugal is not clear, but may include infection control staffing, antibiotic usage and lower prioritisation by hospitals. Some progress is being made in Portugal with the recent launch of a national strategy to control healthcare-associated infection. However, the financial climate and somewhat fragmented healthcare system (compared with the NHS) will make implementation challenging. But at least it’s a start.

Image: Portugal stamp.