Nasal carriage of Staphylococcus aureus among surgeons and surgical residents: a nationwide prevalence study

The relationship between hand hygiene practices and nasal Staphylococcus aureus carriage in healthcare workers

Background:

The nasal carriage rate of Staphylococcus aureus in healthcare workers (HCWs) is higher than the general population. Their hands serve as vectors for transmitting S.aureus colonized in the nose to patients.

Objectives:

To determine the rate of nasal S.aureus carriage and methicillin resistance in HCWs and to evaluate the relationship between carriage and personal risk factors and hand hygiene behaviors.

Methods:

The questionnaire included questions about sociodemographic characteristics, occupational and personal risk factors for S.aureus carriage, the “Hand Hygiene Belief Scale (HHBS),” and “Hand Hygiene Practices Inventory (HHPI)”. Nasal culture was taken from all participants. Presence of S.aureus, methicillin and mupirocin resistance were investigated in samples.

Results:

The study was carried out with 269 HCWs. The prevalence of S.aureus carriage was 20.1% (n:54). Among 54 S.aureus carriers, only one person had MRSA (0.37%). All S.aureus isolates were susceptible to mupirocin. S.aureus carriage was found to be significantly lower in the smoker group (p:0.015) and in the personnel wearing gloves during the procedures of each patient (p:0.002). S.aureus culture positivity was found to decrease significantly with increasing handwashing frequency (p:0.003). The mean HHPI score was higher in women (p:0.001). The mean HHPI score was lower in the group with nasal carriers than in non-carriers (p:0.176).

Conclusion:

The knowledge of hand hygiene practices, high frequency of handwashing, and wearing different gloves during the procedure of each patient decrease S.aureus nasal carriage in HCWs. In addition mupirocin is still effective in nasal S.aureus carriers.

Unexpected categories at risk of S. aureus nasal carriage among hospital workers

OBJECTIVES

Thirty percent of the general population are Staphylococcus aureus nasal carriers. It has been shown that this increases with repeated contact with patients, but it is not known whether all categories of healthcare workers are at equal risk of carriage. We aimed to explore S. aureus nasal carriage among healthcare professionals.

METHODS

Prospective study conducted in two French university hospitals in 2014 and 2016. Volunteers were screened for S. aureus nasal carriage. Profession and hygiene habits were collected. Based on the results of this initial study, a second study focused on semi-skilled workers and biomedical equipment technicians (BETs) only; participants were given education on the basic rules of hygiene, then re-screened three months later.

RESULTS

In the initial study, 38.8% of the 436 participants were detected as nasal carriers. There was a significant difference in nasal carriage according to professional category (p < 0.0001); the lowest was found among administrative agents (17.3%), followed by healthcare providers (37.4%), laboratory technicians (37.6%). The greatest proportion was found among semi-skilled workers and BETs (52.9%). Spa-typing ruled out the hypothesis of a single clone dissemination among colleagues. After the three-month hygiene awareness campaign, all re-screened individuals remained positive, and with their respective initial strain.

CONCLUSIONS

To the best of our knowledge we report here for the first time that semi-skilled workers and BETs are specifically more at risk of S. aureus nasal colonisation. This striking finding urges hospital hygiene departments to evaluate this specific professional category and implement strategies to improve hygiene awareness.

View point: gaps in the current guidelines for the prevention of Methicillin-resistant Staphylococcus aureus surgical site infections

The authors advocate the addition of two preventative strategies to the current United State’s guidelines for the prevention of surgical site infections. It is known that Staphylococcus aureus, including Methicillin-resistant Staphylococcus aureus (MRSA), carriers are at a higher risk for the development of infections and they can easily transmit the organism. The carriage rate of Staph. aureus in the general population approximates 33%. The CDC estimates the carriage rate of MRSA in the United States is approximately 2%. The first strategy is preoperative screening of surgical patients for Staph. aureus, including MRSA. This recommendation is based upon the growing literature which shows a benefit in both prevention of infections and guidance in preoperative antibiotic selection. The second is performing MRSA active surveillance screening on healthcare workers. The carriage rate of MRSA in healthcare workers approximates 5% and there are concerns of transmission of this pathogen to patients. MRSA decolonization of healthcare workers has been reported to approach a success rate of 90%. Healthcare workers colonized with dangerous pathogens, including MRSA, should be assigned to non-patient contact work areas. In addition, there needs to be implemented a safety net for both the worker’s economic security and healthcare. Finally, a reporting system for the healthcare worker acquisition and infections with dangerous pathogens needs to be implemented. These recommendations are needed because Staph. aureus including MRSA is endemic in the United States. Policies regarding endemic pathogens which are to be implemented only upon the occurrence of a facility defined “outbreak” have to be questioned, since absence of infections does not mean absence of transmission. Optimizing these policies will require further research but until then we should error on the side of patient safety.

Underestimation of Staphylococcus aureus (MRSA and MSSA) carriage associated with standard culturing techniques: One third of carriers missed

OBJECTIVES

Nasal carriers of Staphylococcus (S.) aureus (MRSA and MSSA) have an increased risk for healthcare-associated infections. There are currently limited national screening policies for the detection of S. aureus despite the World Health Organization's recommendations. This study aimed to evaluate the diagnostic performance of molecular and culture techniques in S. aureus screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on S. aureus detection in orthopaedic patients.

METHODS

Paired nasal swabs for polymerase chain reaction (PCR) assay and culture of S. aureus were collected from a study population of 273 orthopaedic outpatients due to undergo joint arthroplasty surgery.

RESULTS

The prevalence of MSSA nasal colonization was found to be between 22.4% to 35.6%. The current standard direct culturing methods for detecting S. aureus significantly underestimated the prevalence (p = 0.005), failing to identify its presence in approximately one-third of patients undergoing joint arthroplasty surgery.

CONCLUSION

Modelling these results to national surveillance data, it was estimated that approximately 5000 to 8000 S. aureus surgical site infections could be prevented, and approximately $140 million to $950 million (approximately £110 million to £760 million) saved in treatment costs annually in the United States and United Kingdom combined, by using alternative diagnostic methods to direct culture in preoperative S. aureus screening and eradication programmes.Cite this article: S. T. J. Tsang, M. P. McHugh, D. Guerendiain, P. J. Gwynne, J. Boyd, A. H. R. W. Simpson, T. S. Walsh, I. F. Laurenson, K. E. Templeton. Underestimation of Staphylococcus aureus (MRSA and MSSA) carriage associated with standard culturing techniques: One third of carriers missed. Bone Joint Res 2018;7:79-84. DOI: 10.1302/2046-3758.71.BJR-2017-0175.R1.

Whole genome SNP typing to investigate methicillin-resistant Staphylococcus aureus carriage in a health-care provider as the source of multiple surgical site infections

BACKGROUND

Prevention of nosocomial transmission of infections is a central responsibility in the healthcare environment, and accurate identification of transmission events presents the first challenge. Phylogenetic analysis based on whole genome sequencing provides a high-resolution approach for accurately relating isolates to one another, allowing precise identification or exclusion of transmission events and sources for nearly all cases. We sequenced 24 methicillin-resistant Staphylococcus aureus (MRSA) genomes to retrospectively investigate a suspected point source of three surgical site infections (SSIs) that occurred over a one-year period. The source of transmission was believed to be a surgical team member colonized with MRSA, involved in all surgeries preceding the SSI cases, who was subsequently decolonized. Genetic relatedness among isolates was determined using whole genome single nucleotide polymorphism (SNP) data.

RESULTS

Whole genome SNP typing (WGST) revealed 283 informative SNPs between the surgical team member's isolate and the closest SSI isolate. The second isolate was 286 and the third was thousands of SNPs different, indicating the nasal carriage strain from the surgical team member was not the source of the SSIs. Given the mutation rates estimated for S. aureus, none of the SSI isolates share a common ancestor within the past 16 years, further discounting any common point source for these infections. The decolonization procedures and resources spent on the point source infection control could have been prevented if WGST was performed at the time of the suspected transmission, instead of retrospectively.

CONCLUSIONS

Whole genome sequence analysis is an ideal method to exclude isolates involved in transmission events and nosocomial outbreaks, and coupling this method with epidemiological data can determine if a transmission event occurred. These methods promise to direct infection control resources more appropriately.

Prevalence of Staphylococcus aureus from nares and hands on health care professionals in a Portuguese Hospital

AIMS

The main goal was to estimate the prevalence of methicillin-resistant Staphylococcus aureus on hands and in nose of health care professionals.

METHODS AND RESULTS

Detection of Staph. aureus on hands or in the nose of 169 individuals was performed. Nasal and hand carriage was found in 39·6 and in 8·9% respectively. About 17·2% of the individuals were carriers of methicillin-resistant Staph. aureus (MRSA) in the nose and 4·7% on hands. The majority of nasal MRSA were resistant to β-lactams, erythromycin and ciprofloxacin. All nasal MRSA were SCCmec type IV and Panton-Valentine leukocidin (PVL) negative. One MRSA isolated from hand was SCCmec type V. About 75·6% of MRSA isolates presented the same or closely related restriction patterns. Sixty per cent of Staph. aureus from hands and from noses from the same individual were the same strain.

CONCLUSIONS

MRSA nasal carriage was high considering healthy health care professionals but in accordance with high level of MRSA infection in Portugal. Isolates recovered in this study seemed to be different from major clones previously isolated in other Portuguese hospitals.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings may have implications on the knowledge of healthy health care workers as vehicles of MRSA infections among the community. Presence of several virulence factors may contribute to increased pathogenesis in case of infection.