Contamination

The effect of closing and cleaning wards on infection rates

Jon Otter (@jonotter) Contamination, Disinfection, MRSA , , , ,

Not so long ago, the UK Government ordered a national ‘deep clean’. This prompted a fair amount of debate among experts and the public. If the NHS needed a spring clean, then does that mean that it was dirty in the first place? Perhaps. There does not seem to have been a formal evaluation of impact, but there is some rationale for closing and cleaning wards. For example, this paper from the early 1970s evaluated the impact of closing and cleaning five wards in London.

The five wards (four surgical and one medical) had an outbreak of MRSA (termed ‘cloxacillin-resistant S. aureus’). Rates of infection (termed ‘sepsis’) were monitored on the study wards before and after closing and cleaning. Wards were closed to admissions and emptied of patients. All fabrics were sent for laundering and all left over supplies were discarded. Cleaning comprised washing floors, walls and all other surfaces with hot water containing detergent; bed frames and furniture were also washed. The length of time that all this cleaning too is not specified, but I suspect it took place over several days. Crucially, staff and patients were screened for carriage of epidemic strains of S. aureus; colonised patients were not re-admitted after ward cleaning where possible.

The charts below show the impact on all infections (Figure 1), all S. aureus infection (Figure 2) and MRSA infection (Figure 3). Infection rates were compared 3 months before vs. 3 months after cleaning on Wards 1-3 and 6 months before vs. 6 months after on Wards 4 and 5. As you can see, the impact was pretty dramatic.

Noone Fig 1

Figure 1. Total infection rate (proportion of admissions infected) on the five wards before vs. after ward closing and cleaning.

Noone Fig 2

Figure 2. S. aureus infection rate (proportion of admissions infected) on the five wards before vs. after ward closing and cleaning.

Noone Fig 3

Figure 3. MRSA infection rate (proportion of admissions infected) on the five wards before vs. after ward closing and cleaning.

The poor reduction in total infection rate on Ward 1, a gynecological ward, (Figure 1) is largely due to high Gram-negative infection rates before and after cleaning, most likely explained by endogenous urinary tract infections. Reductions in total infection rate and S. aureus infection rate appeared to be less on Wards 4 and 5, which could be influenced by the fact that rates were compared for 6 months pre and post ward closing and cleaning rather than 3 months on Wards 1-3. The impact of a one off environmental intervention is likely to diminish over time. It’s also interesting to note that the MRSA infections identified on Ward 5, a general surgical ward, after cleaning were due to a different strain of MRSA (determined by phage typing and antibiogram) than before cleaning. This new strain matched the outbreak strain from Ward 2. Two of the patients on Ward 5 who became infected with this strain were operated on in the same theatre as the infected patients from Ward 2 within two weeks of one another. Four other patients (on different wards) also appeared to acquire the strain in the same operating theatre.

The study has several important limitations. It is not possible to be certain whether active screening and isolation or ward closing and cleaning were responsible for the reduction in infection rates; it was probably combined impact. The study design lacked the rigor of more modern investigations: infection rates were not expressed in terms of patient-days and infection rates were compared for different time periods making direct comparison of the impact across the five wards difficult. Also, no environmental sampling was conducted to demonstrate the efficacy of the cleaning procedure (both initially and in terms of recontamination).

Notwithstanding these limitations, the study provides evidence that ward closing and cleaning combined with active screening and selective readmission resulted in a dramatic reduction in the rate of nosocomial infection on five study wards. The impact appeared to be most pronounced in the first three months, which is consistent with a reduction in environmental contamination. Outbreaks of MRSA were eradicated by closing and cleaning on all five study wards. However, there was evidence of new nosocomial transmission following the re-admission of infected patients. Finally there was some interesting circumstantial evidence of transmission within operating theatres.

Article citation: Noone P, Griffiths RJ. The effect of sepsis rates of closing and cleaning hospital wards. J Clin Pathol 1971;24:721-725.

This is what happens when norovirus “sprays” from a toddler

Jon Otter (@jonotter) Contamination, Norovirus , ,

baby changeAn outbreak report in the Journal of Infectious Diseases tells the fascinating story of a norovirus outbreak in a car (auto*) dealership in Oregon that was initially thought to be foodborne, but was eventually traced to contaminated surfaces on a baby changing table (diaper changing station*) in a public toilet (restroom*). The outbreak had a startlingly high attack rate, affecting 75% of 16 employees who attended a team meeting. A thorough investigation of the restaurant that provided the sandwiches for lunch turned out to be a blind alley following the recollection of a staff member of a toddler with “spraying” diarrhoea using the baby changing table in the public toilet of the dealership. The (generous) mother left the mess for the staff member to clean up, which was accomplished using, wait for it, dry paper towels.

The environmental investigation included samples from the baby changing table in the dealership and some ‘control’ samples from 14 baby changing tables in public toilets throughout the state. Norovirus of the same genotype as the outbreak strain was identified from the baby changing table in the car dealership, but norovirus was not identified from the control baby changing tables.

Some limitations of the outbreak include the fact that it is difficult to disentangle the relative importance of the environmental reservoir and secondary transmission via contaminated food. The PCR method used for environmental sampling does not assure that the norovirus RNA identified on the baby changing table was viable. Also, the environmental norovirus isolates could not be sequenced meaning that they could not be sequence-matched with the patient isolates.

Perhaps the most shocking part of the story is that the image of visible soiling on the baby changing table (after two rounds of cleaning) was consistently viewed on baby changing tables in public toilets. Or perhaps it’s even more shocking that only 3 of the 12 affected individuals actually took time off work. As a “survivor” of a norovirus outbreak that swept through the Otter household in 2012, I can vouch for the fact that a) you need to take time off work and b) you ought to take time off work!

One important discussion point was the finding of Dr Carling’s group that baby changing tables were least likely to be cleaned on cruise ships, a setting in which persistent norovirus outbreaks are common. This outbreak report and Dr Carling’s earlier work highlight an important deficiency in how to clean and disinfect baby changing tables in public toilets. As a frequent user over the past 14 months, I can vouch for the fact that, much like a hospital bed, turnover is high which pressurizes effective terminal disinfection! I agree with the authors that disinfection with a chlorine-containing disinfectant would be ideal, but question whether this is feasible in practice.

There’s surprisingly little data supporting the role of environmental contamination in the transmission of norovirus. I’m persuaded by the various outbreaks affecting separate cohorts of patients / staff on cruise ships or aeroplanes, but this outbreak is even more compelling due to the environmental findings. Quantifying the role of the environment in the transmission of norovirus is difficult to study because it always occurs in outbreaks (hence difficult to perform a controlled study). But I’d be interested to see whether the “prior room occupancy” concept that has been established for other environmentally-associated pathogens holds true for norovirus.

Article citation: Repp KK, Hostetler TP, Keene WE. A norovirus outbreak related to contaminated surfaces. J Infect Dis 2013;208:295-298.

Also, take a look at Dr Repp’s blog.

* = for my American readers! Current data indicates that around 40% of the readers of this blog are US based, 40% are UK based and 20% are rest of world!

Evidence that iphones are less contaminated than blackberrys?

Jon Otter (@jonotter) Contamination , ,

iphone

Not so long ago, the use of mobile phones in hospitals was banned for both patients and staff. Nowadays, the use of mobile phones by both patients and staff in hospitals has skyrocketed, and is starting to be embraced with the advent of useful clinical apps. However, as the use of mobile phones in hospitals increases, there is a risk that contaminated phones become a new and difficult-to-manage site for contamination and transmission.

I own a blackberry and my wife owns an iphone. We often talk long into the night about the relative benefits of the phones, and the utility of the blackberry keypad compared with the touchscreen of the iphone is my strongest suit. However, a study from UCL in London provides evidence that the keypad of the blackberry is likely to be more contaminated than the touchscreen of the iphone. Sixty-seven phones were sampled, approximately half of which were touchscreen and the other half were keypad phones. Colony counts were significantly higher on keypad phones, which were also more likely to be contaminated with MRSA or VRE. Overall, 13% of the phones grew either MRSA or VRE, highlighting the potential importance of these sites in transmission.

So why the higher counts from the keypad phones? It seems likely that the nooks and crannies on the keypads allow for the buildup of dust and microbial contamination over time, and make the phones more difficult to clean.

It is unacceptable that 13% of mobile phones are contaminated with multidrug-resistant organisms such as MRSA and VRE. Appropriate disinfection policies are urgently required for these personal, mobile reservoirs of contamination.

Article citation:

Pal et al. Keypad mobile phones are associated with a significant increased risk of microbial contamination compared to touch screen phones. J Infect Prevent 2013;14:65-68.

No need to worry about environmental contamination with Enterobacteriaceae…or is there?

Jon Otter (@jonotter) Contamination, CRE , , , , ,

It was once thought that only bacterial endospores would survive on dry hospital surfaces for extended periods (measured in days and weeks rather than hours). Microbiological data indicates that a range of vegetative bacteria can survive on dry surfaces for extended periods. Whilst differing testing methods and conditions make comparison of survival times between studies difficult, it is clear that non-fermenting Gram-negative bacteria (such as Acinetobacter baumannii and Pseudomonas aeruginosa) survive considerably longer than the Enterobacteriaceae (such as Klebsiella pneumoniae and Escherichia coli).  However, the Enterobacteriaceae can survive for more than a month on dry surfaces. Indeed, a 2009 laboratory study highlighted substantial strain variation in the survival of K. pneumoniae, with the survival of three strains ranging from a 6-log reduction inside 3 weeks to a 1-log reduction over six weeks.

Several recent studies have evaluated environmental contamination with ESBL-producing Enterobacteriaceae. One French study evaluated surface contamination on five standardized sites surrounding patients infected or colonized with ESBL-producing Klebsiella spp. (n=48) or ESBL-producing E. coli (n=46). Environmental contamination was significantly more likely in the rooms of Klebsiella spp. patients (31% of 48 rooms positive; 6% of 240 sites positive) vs. E. coli patients (4% of 46 rooms positive; 1% of 230 sites sites). Multiple regression identified carriage of ESBL-producing K. pneuomiae as the only independent predictor of ESBL environmental contamination (adjusted odds ratio=10.38, 95% confidence interval = 1.24-228.58). Surprisingly, only 52% of the ESBL-producing isolates were identical to the patients in the room, suggesting survival of ESBL-producing bacteria from prior occupants or importation into the room. Another French study with a similar design identified comparable rates of contamination, and also found that contamination was significantly more likely with K. pneumoniae than with E. coli.

environmental sampling

Environmental contamination with C. difficile spores, VRE and non-fermenting Gram-negative bacteria is now a well-established route of transmission. Whilst the same cannot be said for the Enterobacteriaceae, these studies combined with an Israeli article recently featured on this Micro Blog, show that environmental contamination with Enterobacteriaceae may be more important than previously thought. These findings are particularly important in light of the recent global spread of carbapenemase-producing K. pneumoniae.

Article citations:

Guet-Revillet H, Le Monnier A, Breton N et al. Environmental contamination with extended-spectrum beta-lactamases: is there any difference between Escherichia coli and Klebsiella spp? Am J Infect Control 2012; 40: 845-848.

Gbaguidi-Haore H, Talon D, Hocquet D, Bertrand X. Hospital environmental contamination with Enterobacteriaceae producing extended-spectrum β-lactamase. Am J Infect Cont 2013; Jan 18 [Epub ahead of print].

MDR-Acinetobacter baumannii beats MRSA in the war for ICU predominance

Jon Otter (@jonotter) Acinetobacter, Contamination, MRSA , , , , ,

A. baumannii is a notorious nosocomial pathogen due to a combination of its environmental resilience, its association with antimicrobial resistance and its outbreak potential. Colonized patients and contaminated environments are thought to be the primary reservoirs for the nosocomial transmission of this pathogen.

A recent study from China suggests that carriers of MDR A. baumannii (MDR-AB) show stronger ability to contaminate their immediate environment than those carrying MRSA and that MDR-AB spreads more easily and rapidly among inpatients compared with MRSA. The 20-month study was conducted in a respiratory ICU (RICU) where active screening of patients and targeted environmental screening for MRSA and MDR-AB were performed. The environmental samples were collected from 6 sites on patients’ bed linens.

High levels of carriage and nosocomial acquisition were found among the 175 patients admitted to the RICU where 44% of the patients were MDR-AB positive (80% of which were hospital acquired) and 24% of patients were MRSA carriers (60% of which were hospital acquired). Interestingly, 15.4% of the patients were co-carriers of MRSA and MDR-AB.

Researchers found that bed linens were commonly contaminated with MRSA and MDR-AB and that the contamination rate for MDR-AB was significantly higher than that of MRSA. Of the 576 MRSA samples, 26.6% were positive, and 51.6% of the 1,176 MDR-AB swabs were positive. This is surprising given the strict daily extensive cleaning practices, thrice daily bed linen changes and stringent terminal sterilization immediately after discharge of carriers. Researchers used the weekly colonisation pressure adjusted by degree of bed linen contamination (WCPe) and weekly acquisition rate (WAR) as parameters to evaluate the potential spread of these pathogens among inpatients. They found a positive significant correlation between the WCPe and WAR values for both organisms but both the WCPe and WAR of MDR-AB were significantly higher than for MRSA.

This study shows that environmental contamination with MDR-AB and the rate of its nosocomial acquisition is significantly higher than those for MRSA, which may explain why MDR-AB is able to spread among inpatients more rapidly. Although the study found positive significant correlation between the WCPe and WAR in the subsequent weeks, this correlation does not necessarily indicate causality. Nevertheless, the authors conclude that reduction of environmental contamination close to MDR-AB positive patients is crucial in controlling MDR-AB transmission.

Article citation:

Sui W, Wang J, Wang H et al. Comparing the transmission potential of Methicillin-resistantStaphylococcus aureus and multidrug-resistant Acinetobacter baumannii among inpatients using target environmental monitoring. Am J Infect Control. 2012. doi: 10.1016/j.ajic.2012.08.007

Where the wild things are

Jon Otter (@jonotter) Contamination, CRE , ,

Carbapenem-resistant Enterobacteriaceae (CRE) are a major threat to public health worldwide and Israel is among the countries with the highest rates of these pathogens. A concerted campaign has done a good job of bringing the national outbreak under control, but problems persist1. An Israeli hospital investigated the extent of environmental contamination with CRE in the vicinity of 34 CRE-carriers using two different sampling methods; contact plates and swabs (with or without enrichment). Pilot sampling was performed to identify the five sites that were most likely to be contaminated (pillow, crotch and leg area on the bed, personal bedside table and infusion pump). To investigate the effect of cleaning on the recovery of CRE, the five sites were sampled at two different times; 4 and 24 hr after rooms were cleaned and patient cloths and sheets were changed.

12-PDR-A290-278

The study detected CRE in the surrounding environment of most (88%) of the patients sampled, showing that a high proportion of carriers shed these pathogens into their environment which can then be transmitted. Recovery was highest in the carrier’s immediate environment with the patient bed being the most contaminated. Not surprisingly, recovery of CRE from the environment was reduced when sampling was done 4 hr after cleaning compared to 24 hr after cleaning (21% of sites contaminated vs 27%). However these results also highlight the speed by which the patient environment is re-contaminated with CRE after cleaning. The study also showed that the choice of the detection method is also important and reported that contact plates were more efficient at recovering CRE than swabs even with enrichment broth.

The high rate of recovery of CRE from the environment in this study is surprising. Hence, hospitals with CRE-carriers should expect the environment in the vicinity of these patients to be contaminated. Regular and thorough cleaning of the patient environment and equipment should be an integral part of the hospital’s infection control strategy to reduce the spread of these pathogens.

Article citation:

Lerner A, Adler A, Abu-Hanna Jet al.Environmental contaminationby carbapenem-resistantenterobacteriaceae. J Clin Microbiol 2013;51:177-81.

References

1.       Schwaber MJ, Lev B, Israeli Aet al. Containment of a country-wide outbreak of carbapenem-resistant Klebsiella pneumoniae in Israeli hospitals via a nationally implemented intervention. Clin Infect Dis 2011; 52: 848-855.

Curtain twitchers should beware

Jon Otter (@jonotter) Contamination ,

curtains

A study published in ICHE by a team from the University of Iowa evaluated the effectiveness of antimicrobial impregnated hospital curtains. The powerful double-blinded RCT study design of 15 standard curtains and 15 curtains impregnated with a metal-alloy based ‘complex element compound (CEC)’ meant there was no doubt that the differences between the two study arms were due to the curtains. The antimicrobial CEC curtains took longer to become contaminated (14 vs. 2 days) but were not significantly less contaminated in the later culture results.

The authors conclude that the ‘Use of privacy curtains with antimicrobial properties could increase the time between washings and may potentially play a role in decreasing pathogen transmission.’

The list of pathogens cultured from the curtains during the study is compelling: MRSA, VRE, Acinetobacter species, methicillin-susceptible S.aureus, E. coli, Pseudomonas species, Klebsiella species, vancomycin-susceptible enterococci, Enterobacter species, Leclercia adecarboxylata, Pantoea agglomerans, Stenotrophomonas maltophilia, Proteus mirabilis, Serratia plymuthica, Sphingomonas paucimobilis, and Citrobacter freundii. These findings highlight the importance of curtains as a potential reservoir for pathogen transmission.

In terms of study limitations, there were some structural differences between the curtains (woven vs. knitted) that could have contributed to the difference between the groups. Also, it would have been useful to know more about the exact chemical composition of the complex element compound (CEC) used. Finally, the authors did not assess contamination with C. difficile spores and effectiveness of the chemical compound used against spores seems unlikely.

I wonder how often privacy curtains are changed on average? As with any other antimicrobial intervention, the product is only as good as the practice. This study provides some useful data on a novel product that could help to reduce the overall burden of microbial contamination in healthcare facilities and, in doing so, contribute to increased patient safety.

Article citation: Schweizer M, Graham M, Ohl M et al. Novel hospital curtains with antimicrobial properties: a randomized, controlled trial. Infect Control Hosp Epidemiol 2012; 33: 1081-5.