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Healthcare worker screening for nosocomial pathogens 

Healthcare worker screening for nosocomial pathogens
Healthcare worker screening for nosocomial pathogens

Paul Van Buynder

and Elizabeth Brodkin

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date: 03 December 2020

Key points

  • Healthcare workers (HCW) are both at risk of becoming infected in the health care setting as well as being a known source of nosocomial infection.

  • Employers and HCW have an ethical responsibility to prevent occupationally acquired infections and avoid causing harm to patients by transmitting disease.

  • After any recognized blood borne pathogen (BBP) exposure incident, timely post-exposure risk assessment, along with a schedule of follow-up BBP screening should be undertaken.

  • Screening for and management of potential transmission sources can reduce risks.

  • HCW vaccination strategies can further reduce risks.

Screening and management of specific pathogens

Blood-borne pathogens

Health care worker (HCW) screening for blood-borne pathogens (BBP) focuses on the three viruses which are responsible for most health care-associated blood-borne infections, Human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). Infection control guidelines for BBP screening of HCWs reflect an increasing focus on the potential risk of nosocomial BBP transmission from an infected HCW-to-patient, in addition to early identification of patient-to-HCW BBP transmission [1,2].

Guidelines for HCW screening and subsequent management of infected HCW vary across jurisdictions internationally, with differing thresholds for the scope of practice of infected HCW. Some jurisdictions, such as United States of America (USA), Canada, and Australia allow for case-by-case review of infected HCWs by an expert review committee to assess the scope of practice restriction [3,4].

Voluntary screening for HBV, HCV and HIV infection is a professional and ethical responsibility of each HCW who has potential exposure to BBPs. HCW regulatory authorities in many jurisdictions, such as the USA, Canada, Australia, and a number of European countries promote, but do not mandate BBP screening by HCW. In the United Kingdom (UK), such screening is explicitly mandated for new (but not currently practising) HCW who will perform ‘exposure prone procedures’ (EPP), which are procedures that are assessed to pose a higher risk of HCW-to-patient BBP transmission [5]‌. Most guidelines either make no recommendation for repeat BBP screening (e.g. U.K.) or do not recommend a specific frequency of BBP screening in HCWs not previously known to be infected (e.g. U.S.A, Canada, Germany). Recent Australian guidelines propose a minimum one-year periodicity for HCW performing EPP. Some regulatory agencies advise a re-screening frequency based on personal assessment of risk of acquisition of BBP infection.

In general, where guidelines recommend practice restrictions for infected HCW, exclusions are limited to performance of EPP only. Notably, UK guidelines indicate that the intensive care setting does not ‘generally’ involve EPPs by medical or nursing staff; however, these guidelines indicate certain procedures involving accident or emergency care as EPP, which could possibly be performed in critical care settings. Further complicating the assessed potential for performing EPP in critical care settings is a lack of international consensus in defining or categorizing specific procedures as EPP.

After any recognized BBP exposure incident, timely post-exposure risk assessment, along with a schedule of follow-up BBP screening should be undertaken. Where indicated, HIV post-exposure prophylaxis should ideally be initiated within two hours of exposure, while HBV prophylaxis, including hepatitis B immune globulin, and/or hepatitis B vaccine, is preferably begun within 48–72 hours of exposure.

Hepatitis B pre-exposure immunization and screening of post-vaccination anti-HBs level one to three months after the final vaccine dose are highly recommended for all HCW. Hepatitis B vaccine non-responders, in addition to HCW performing EPP, should have further Hepatitis B surface Antigen (HBsAg) testing and HBV-infected HCW should undergo HBeAg and/or HBV-DNA screening to assess their degree of infectivity. Although HBeAg-positive status generally requires exclusion from performing EPPs, guidelines for similarly restricting HBV-infected, HBeAg-negative HCWs differ according to varying HBV-DNA levels, ranging from: any level of detectable HBV-DNA (Australia); 103 GE/mL (UK); 104 GE/mL (U.S.A. and European Consensus Group); or 105 GE/mL (Netherlands). Jurisdictions that permit HCWs with detectable HBV-DNA to continue performing EPPs, require varying frequency of ongoing nucleic acid testing to monitor viral levels, ranging from every 3 months in Australia, to twice per year in the USA, and annually in the UK [6]‌.

Variance across jurisdictions also exists for managing HCV-infected HCW. In general anti-HCV-positive, HCV-RNA-positive HCW are restricted from performing EPP. Some guidelines (USA) permit HCV-infected HCW with HCV-RNA levels up to 104 GE/mL who have not been implicated in cases of HCW-to-patient HCV transmission, to continue performing EPP although affected HCW are required to ‘double-glove’ and undertake semi-annual HCV nucleic acid testing. Australian guidelines make provision for HCW who achieve a sustained viral response following HCV treatment (i.e. undetectable HCV-RNA 6 months after completion of treatment) to resume performing EPP, with annual HCV-RNA rescreening.

Most jurisdictions exclude HIV-infected HCW from performing EPPs, regardless of HIV-RNA level (even if ‘undetectable’ by sensitive nucleic acid testing). Some USA guidelines are more permissive (i.e. Society for Healthcare Epidemiology of America, or SHEA), allowing HIV-infected HCW with HIV-RNA levels less than 500 GE/mL to continue performing EPP, with similar ongoing practice and follow-up test requirements as for HCV [3]‌.

As available data increases, HCW screening and management guidelines will require ongoing review to optimally manage BBP-infected HCWs who achieve long term sustained, viral response using increasingly effective therapies.


All health care settings require a tuberculosis (TB) infection control program, a key component of which is screening HCW who are at risk for disease or who might be exposed to infected persons or clinical specimens [7]‌.

Baseline screening of HCW allows for detection and treatment of latent and active TB disease before employment begins, and provides a basis for comparison should the worker be exposed to Mycobacterium TB. New HCW (or staff with no evidence of prior screening) who will be exposed to patients or clinical specimens, should only begin work after they have undergone a health check and TB screen, or can produce evidence of having been screened in the previous 12 months. The health check should include:

  • Personal or family history of TB.

  • Any signs and symptoms of TB disease.

  • Evidence of Tuberculin skin testing (TST) or Interferon Gamma release Assay (IGRA) testing and Bacille Calmette–Guérin, (BCG) scar check by an occupational health professional.

  • Previous TST results in the last five years if available.

HCWs should not begin work if they have signs and symptoms of active TB disease.

New HCWs who are not entrants from high incidence countries and have not previously had BCG vaccination should be offered TST testing. If the TST is positive IGRA testing should be performed. If both the TST and IGRA are positive the worker should have a chest X-ray and a medical assessment for latent or active disease.

IGRA testing should be offered to new HCW who have recently arrived from high incidence countries or who have worked in settings where TB is prevalent. If the IGRA is positive the HCW should be referred for medical assessment [8]‌.

The frequency of ongoing screening for established HCW should be determined by the risk of exposure in their particular setting. Risk varies by patient population, prevalence of TB in the community, occupational group, and effectiveness of TB infection control measures. Settings in which infected persons or clinical specimens are unlikely to be present are considered low risk. Medium risk refers to settings in which HCW will or are likely to be exposed to infected persons or specimens. Potential ongoing transmission should be applied to any setting where there is evidence of person-to-person transmission during the previous year.

After baseline screening for TB, additional screening of HCW in low risk settings is not needed unless an exposure to M. TB occurs. HCW in medium risk settings should be screened annually by health check, and by TST/IGRA testing for those with negative baseline testing. In settings with potential ongoing transmission workers may need to be screened every eight to 10 weeks until the problem has been corrected and transmission has ceased. HCW who transfer from one setting to another may be at higher risk in the new setting and the frequency of screening should be adjusted accordingly.

Methicillin-resistant Staphylococcus aureus

HCW can become colonized with MRSA. One retrospective review of published data found HCW to have an average colonization rate of 5% and transmission to be documented from both transiently and persistently colonized HCW. No trials have been published on the benefit of routine HCW screening for MRSA colonization although this practice occurs in the Netherlands, Scandinavia, and Western Australia. This practice is not routinely recommended unless staff were epidemiologically linked to new MRSA cases or a cluster of infections, or if an outbreak persists despite appropriate control measures. Molecular testing has been helpful in these situations. Surveillance for skin and soft tissue infections in staff is also warranted in an outbreak. Eradication therapy should be provided for positive staff in these settings.

Screening of patients in critical care areas has been deemed cost effective by a Health Protection Authority modelling study and screening of all hospital admissions is required in the United Kingdom, but remains contentious with studies examining the link between colonization and infective complications showing conflicting results [9,10].

Other antibiotic resistant organisms

Routine screening of healthcare workers for vancomycin resistant enterococci (VRE), carbapenem-resistant Enterobacteriaceae (CRE) and Extended Spectrum Beta Lactamase (ESBL) producing organisms is not recommended as there is no evidence that rectal colonization of staff contributes to transmission.

Vaccination of health care workers

Recommendations for vaccination of HCW are largely based on either risk to the HCW for acquiring disease or the risk of HCWs transmitting disease to patients. A review of HCW vaccination status should occur at the time of hire and then annually with influenza vaccination. Robust HCW vaccination policies should be accompanied by secure record systems so that susceptible individuals can be identified during times of outbreaks [11].

Hepatitis B vaccine should be made available at no cost to all HCW who are exposed occupationally to infectious materials, preferentially during training prior to exposure. The three dose regime at zero, one, and six months produces a protective antibody response in over 90% of healthy young adults and lasts for over 20 years in vaccine responders. Post vaccination serologic testing should be undertaken after the third dose to confirm the presence of hepatitis B surface antibody (anti-HBs >10mIU/mL). For those with an inadequate immune response after a complete vaccine series, (i.e. less than 10 IU/L), a second complete series of hepatitis B vaccine is recommended in many jurisdictions. UK guidelines also recommend offering an additional single vaccine dose to those with an intermediate response (i.e. 10-100 IU/L).

Non-responders who are not infected with Hepatitis B are susceptible and should be educated about preventing infection and post-exposure prophylaxis. Non-responders who are HBsAg positive should be counselled about preventing transmission to others and have their practice reviewed. Post exposure prophylaxis after significant exposure to blood or body fluids should be based on the HBsAg status of the source and the immune status of the exposed HCW. HCW engaging in high- risk personal practices associated with an increased risk of non-occupational acquisition of blood borne viruses have a responsibility to regularly check their status.

Many HCW are infected with influenza each year. Vaccinating HCW decreases morbidity in health care settings particularly in long term care and vaccination helps maintain a workforce in winter by reducing absenteeism. Professional bodies have recommended HCW vaccination as an ethical imperative for many years, but uptake has been almost universally disappointing and often less than 50%. In view of the failure of education, many organizations and some United States jurisdictions have now mandated HCW influenza vaccination [12].

Measles remains common in some parts of the world leading to travel related importations and risks of transmission even in areas where measles has been declared eliminated. Persons infected with measles are likely to seek medical care and measles transmission has been shown to occur in medical settings during outbreaks. HCW are at higher risk of acquiring measles. Exposure response in medical settings is expensive and entails reviewing measles immunity, and excluding and vaccinating the non-immune. All HCW born after 1956 should be vaccinated with two doses of Measles Mumps Rubella (MMR) vaccine and a record should exist in all facilities documenting these doses or documenting laboratory evidence of immunity or disease. Serological confirmation after vaccination is not required.

Mumps transmission in medical settings is also well recognized and the management of cases associated with similar economic costs as measles. Immunity to mumps vaccine wanes over time and correlates of protection are not known. All HCW should provide presumptive evidence of immunity to mumps. Despite waning immunity, two doses of MMR vaccine is considered sufficient protection.

Evidence of transmission of rubella in medical settings is scant in areas where rubella elimination has been achieved although it was common prior to that. All HCW should have documented evidence of immunity. History of disease is not considered adequate.

Pertussis is a highly contagious disease with a high risk of hospitalization and significant mortality in the very young. Since the widespread use of acellular pertussis vaccines in the last decade, with a duration of protection of only between 5 and 10 years, outbreaks are occurring on a regular basis. Documented transmission within medical settings has occurred and outbreak management is costly. All HCW in contact with young children should receive decennial booster vaccines and consideration should be given to boosting after 5 years in an outbreak setting. Modelling post outbreak has shown that HCW vaccination for pertussis is cost saving.

Vaccination against other preventable diseases such as varicella may be indicated depending on local epidemiology and local vaccination coverage data.


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