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Severe acute respiratory syndrome coronavirus 2 (the cause of COVID 19) in different types of clinical specimens and implications for cytopathology specimen: An editorial review with recommendations
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*Corresponding author: Vinod B. Shidham, MD, FRCPath, FIAC Department of Pathology, Karmanos Cancer Center and Detroit Medical Center, Wayne State University School of Medicine, Detroit, Michigan, United States. vshidham@med.wayne.edu
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Received: ,
Accepted: ,
How to cite this article: Shidham VB, Frisch NK, Layfield LJ. Severe acute respiratory syndrome coronavirus 2 (the cause of COVID 19) in different types of clinical specimens and implications for cytopathology specimen: An editorial review with recommendations. CytoJournal 2020;17:7.
EDITOR’S LETTER
Coronavirus disease 2019 (COVID-19) caused by “Severe acute respiratory syndrome coronavirus 2” (SARS-CoV-2) was first reported in China.[1] This is the third extremely pathogenic human coronavirus which has emerged recently after severe acute respiratory syndrome (SARS) coronavirus and Middle East respiratory syndrome (MERS) coronavirus. SARS-CoV-2 is mainly transmitted by person-to-person contact in community and health-care settings.[2] This pattern of spread demands large-scale and proactive measures to avoid further widespread dissemination. SARS-CoV-2 survives on contaminated dry surfaces and fomites, which facilitate hand to mucous membranes (of the mouth, nose, and eyes) spread.[3,4] This emphasizes the significance of in-depth knowledge about the perseverance of coronavirus on inanimate surfaces.[5] Various fixatives and biocidal agents are widely used in health-care settings including cytopathology laboratories which may impact (and help negate) the spread of this virus.[6,7]
The current review summarizes the available relevant data on this topic about cytopathology laboratory protocols and suggests precautions based on this data. These recommendations may change as new information comes to light. Each institution and laboratory has to adapt and adjust depending on local regulatory limitations. The recommendations suggested at the end of the review discussion should be considered with these things in mind.
At present, the diagnosis of COVID 19 is mostly being accomplished by performing real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) for SARS-CoV-2 on respiratory specimens such as nasopharyngeal swabs.[8] The primary mode of spread, which has led to the global pandemic, is the respiratory route. A report studying different types of clinical specimens from patients (most cases 1–3 days after hospital admission) detected a positive PCR test in about 1% (n = 307) of blood samples, suggesting the systemic nature of the disease in at least a portion of the cases.[9] This study also reported positive results in 29% (n = 153) of fecal samples.[9] Although tests based on PCR have been reported positive in non-respiratory specimens, it does equate with infectivity and so the non-respiratory route of viral transmission is possible but is not proven at this stage.
As mentioned previously, the molecular test to detect SARS-CoV-2 is based on rRT-PCR. This test amplifies viral RNA in a patient’s specimen for the detection of SARS- CoV-2 genetic material.[10] False negatives are possible due to multiple variables including simple technical errors, inadequate collection, improper handling, and shipping. Other possibilities for incorrect results include flawed key reagents in the kit.[11] One study comparing rRT-PCR with computerized tomography (CT), reports that the sensitivity of the test is only 70%.[12] Further compounding the issue, the sensitivity may be lower in some symptomatic cases due to a smaller viral load,[13] but usually the viral load is higher in the early stages of the disease. However, newer tests suggest higher sensitivity with the potential of false positives due to very high sensitivity and possible cross contaminations during the pandemic with the widespread presence of virus (at the level of collection of sample and later during the technical procedure).
As a result, even if the specimen in the cytopathology laboratory is not expected to be positive or even if the molecular test is negative for SARS-CoV-2, all of the specimens should be considered potentially positive. It is therefore mandatory to practice all the universal/standard precautions with basic protective measures while handling any biological specimen irrespective of SARS-CoV-2 status [Tables 1-3].[14-16] All cytology personnel should follow the basic protective measures against SARS-CoV-2 recommended by the World Health Organization (WHO) [Table 2].[16]
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Although, appropriate disinfectants and precautions related to cytopathological/histological fixation and processing of samples during the current COVID 19 pandemic are not known, information can likely be extrapolated from other recent coronaviruses (e.g., SARS and MERS). Similar protocols should be effective to disinfect and inactivate SARS-CoV-2.[17] Thus, once the processing is complete as cytopathologic preparation and after formalin fixation and paraffin embedding for cell-blocks, SARS-CoV-2 if present in the specimen should be inactive.[17]
A study reported that aerosol and fomite transmission of SARS-CoV-2 is possible because the pathogen continues to be infectious for hours in aerosols and for days on surfaces.[18] The findings are comparable to those observed with SARS- CoV-1[19] providing useful information for the current mitigation efforts during this pandemic. The study observed that SARS-CoV-2 survives for up to 24 h on cardboard and plastic/stainless-steel surfaces up to 2–3 days.[18-20]
Many ostensibly clean surfaces and devices within a pathology department (including but not limited to doorknobs, tables and chairs, countertops, desks, keyboards, phones, microscopes, glass slides, slide trays/boards, on-site adequacy carts, door handles, light switches, toilets, faucets, and sinks) may be contaminated with the virus and should be considered potential fomites.[21] The duration for which SARS-CoV-2-like viruses have been reported to persist on various surfaces is listed in Table 4.[22]
Type of surface | Virus | Strain/isolate | Inoculum (viral titer) | Temperature | Persistence |
---|---|---|---|---|---|
Glass | SARS-CoV | P9 | 105 | RT | 4 d |
HCoV | 229E | 103 | 21°C | 5 d | |
Plastic | SARS-CoV | HKU39849 | 105 | 22–25°C | <5 d |
MERS-CoV | HCoV-EMC/2012 | 105 | 20°C | 48 h | |
30°C | 8–24 h | ||||
SARS-CoV | P9 | 105 | RT | 4 d | |
SARS-CoV | FFM1 | 107 | RT | 6–9 d | |
HCoV | 229E | 107 | RT | 2–6 d | |
PVC plastic | HCoV | 229E | 103 | 21°C | 5 d |
Paper | SARS-CoV | P9 | 105 | RT | 4–5 d |
SARS-CoV | GVU6109 | 106 | RT | 24 h | |
105 | RT | 3 h | |||
104 | RT | <3 min | |||
Surgical glove (latex) | HCoV | 229E and OC43 | 5 × 103 | 21°C | <8 h |
Disposable gown | SARS-CoV | GVU6109 | 106 | RT | 2 d |
105 | RT | 24 h | |||
104 | RT | 1 h | |||
Aluminum | HCoV | 229E and OC43 | 5 × 103 | 21°C | 2–8 h |
Metal | SARS-CoV | P9 | 105 | RT | 5 d |
Steel | MERS-CoV | HCoV-EMC/2012 | 105 | 20°C | 48 h |
TGEV | Unknown | 106 | 4°C | >28 d | |
20°C | 3–28 d | ||||
40°C | 4–96 h | ||||
MHV | Unknown | 106 | 4°C | >28 d | |
20°C | 3–28 d | ||||
40°C | 4–96 h | ||||
HCoV | 229E | 103 | 21°C | 5 d | |
Silicon rubber | HCoV | 229E | 103 | 21°C | 5 d |
Wood | SARS-CoV | P9 | 105 | 21°C | 4 d |
Ceramic | HCoV | 229E | 103 | 21°C | 5 d |
Teflon | HCoV | 229E | 103 | 21°C | 5 d |
CCV: Canine coronavirus, HCoV: Human coronavirus, MHV: Mouse hepatitis virus, MERS-Cov: Middle East respiratory syndrome coronavirus, RT: Room temperature, SARS-CoV: Severe Acute respiratory syndrome coronavirus, TGEV: Transmissible gastroenteritis virus, d: Day(s), h: Hours(s), min: Minute(s)
Virus infectivity is defined as the ability of the virus to enter and colonize the host to replicate and reproduce itself with the potential to establish itself as an infection resulting in disease.[22] A previously suggested benchmark, a log10 viral reduction factor of more than 3, is considered as virucidal effectivity against viruses including coronaviruses on surfaces.[23] Formalin and ethanol used in low concentration (usually used as a preservative) decrease the viral infectivity to more than 3 log10.[22]
The effect of time and concentrations of various fixatives and biocidal agents on SARS and a few other viruses are summarized in Table 5. The table shows that for ethanol, 95% ethanol with SARS-CoV (Isolate FFM-1) for 30 s reduces the viral infectivity to more than 5.5 log10; 85% ethanol with SARS-CoV (Isolate FFM-1) for 30 s reduces the viral infectivity to more than 5.5 log10;[24] 80% ethanol with SARS-CoV (Isolate FFM-1) for 30 s reduces the viral infectivity to more than 4.3 log10;[24] 80% ethanol with MERS-CoV (Strain EMC) for 30 s reduces the viral infectivity to more than >4.0 log10;[25] 78% ethanol with SARS-CoV (Isolate FFM-1) for 30 s reduces the viral infectivity to more than 5.0 log10;[26] 70% ethanol with MHV (Strains MHV-2 and MHV-N) for 10 min reduces the viral infectivity to more than >3.9 log10;[27] and 70% ethanol with CCV (Strain I-71) for 10 min reduces the viral infectivity to more than >3.3 log10.[27]
Fixative/Biocidal agent | Concentration (%) | Virus | Strain/Isolate | Exposure time | Reduction of viralinfectivity (log10) |
---|---|---|---|---|---|
Ethanol | 95 | SARS-CoV | FFM-1 | 30 s | >5.5 |
85 | SARS-CoV | FFM-1 | 30 s | >5.5 | |
80 | SARS-CoV | FFM-1 | 30 s | >4.3 | |
80 | SARS-CoV | EMC | 30 s | >4.0 | |
78 | SARS-CoV | FFM-1 | 30 s | >5.0 | |
70 | MHV | MHV-2 and MHV-N | 10 min | >3.9 | |
70 | CCV | I-71 | 10 min | >3.3 | |
Formaldehyde | 1% | SARS-CoV | FFM-1 | 2 min | > 3.0 |
0.7% | SARS-CoV | FFM-1 | 2 min | > 3.0 | |
0.7% | MHV | 10 min | > 3.5 | ||
0.7% | CCV | I-71 | 10 min | > 3.7 | |
0.009% | CCV | 24 h | > 4.0 | ||
Glutardialdehyde | 2.5% | SARS-CoV | Hanoi strain | 5 min | > 4.0 |
2.5% | SARS-CoV | FFM-1 | 2 min | > 4.0 | |
2-Propanol | 100% | SARS-CoV | FFM-1 | 30 s | >3.3 |
75% | SARS-CoV | FFM-1 | 30 s | >4.0 | |
75% | MERS-CoV | EMC | 30 s | >4.0 | |
70% | SARS-CoV | FFM-1 | 30 s | >3.3 | |
50% | MHV | MHV-2 & MHV-N | 10 min | >3.7 | |
50% | CCV | I-71 | 10 min | >3.7 | |
2-Propanol (a) and 1-propanol (b) | a-45% & b-30% | SARS-CoV | FFM-1 | 30 s | >4.3 |
SARS-CoV | FFM-1 | 30 s | >2.8 | ||
Sodium hypochlorite | 0.21% | MHV | MHV-1 | 30 s | >4.0 |
0.01% | MHV | MHV-2 & MHV-N | 10 min | 2.3-2.8 | |
0.01% | CCV | I-71 | 10 min | 1.1 | |
0.001% | MHV | MHV-2 & MHV-N | 10 min | 0.3-0.6 | |
0.001% | CCV | I-71 | 10 min | 0.9 | |
Hydrogen peroxide | 0.5% | HCoV | 229E | 1 min | > 4.0 |
Benzalkonium chloride | 0.2% | HCoV | ATCC VR-759 (strain OC43) | 10 min | 0.0 |
0.05% | MHV | MHV-2 & MHV-N | 10 min | >3.7 | |
0.05% | CCV | I-71 | 10 min | >3.7 | |
0.00175% | CCV | S378 | 3 d | 3.0 | |
Povidone-iodine | 7.5% | MERS-CoV | HCoV-EMC/2012 | 15 s | 4.6 |
4% | MERS-CoV | HCoV-EMC/2012 | 15 s | 5.0 | |
1% | SARS-CoV | Hanoi strain | 5 min | >4.0 | |
1% | SMES-CoV | HCoV-EMC/2012 | 15 s | 4.3 | |
0.47% | SARS-CoV | Hanoi strain | 1 min | 3.8 | |
0.25% | SARS-CoV | Hanoi strain | 1 min | >4.0 | |
0.23% | SARS-CoV | Hanoi strain | 1 min | >4.0 | |
0.23% | SARS-CoV | FFM-1 | 15 s | >4.4 | |
0.23% | MERS-CoV | HCoV-EMC/2012 | 15 s | >4.4 | |
Didecyldimethyl ammonium chloride | 0.0025% | CCV | S378 | 3 d | > 4.0 |
Chlorhexidine digluconate | 0.02% | MHV | MHV-2 & MHV-N | 10 min | 0.7-0.8 |
0.02% | CCV | I-71 | 10 min | 0.3 |
CCV: Canine coronavirus; HCoV: Human coronavirus; MHV: Mouse hepatitis virus; MERS-Cov: Middle East respiratory syndrome coronavirus; SARS-CoV: Severe acute respiratory syndrome coronavirus; min: Minute(s); s: Second(s)
Similarly for formalin, 1% formaldehyde with SARS-CoV (Isolate FFM-1) for 2 min reduces the viral infectivity to more than >3.0 log10;[26] 0.7% formaldehyde with SARS-CoV (Isolate FFM-1) for 2 min reduces the viral infectivity to more than >3.0 log10;[26] 0.7% formaldehyde with MHV for 10 min reduces the viral infectivity to more than >3.5 log10;[27] 0.7% formaldehyde with CCV (Strain I-71) for 10 min reduces the viral infectivity to more than >3.7 log10;[27] and 0.009% formaldehyde with CCV for 24 h reduces the viral infectivity to more than >4.0 log10[28] [Table 5].
About 95% ethanol reduces the viral infectivity to more than 5.5 in 30 s and formaldehyde even in the concentration of 1% decreased the viral infectivity to more than 3 in 2 min [Table 5].[22] Various reagents such as ethanol and 10% formalin (3.7% formaldehyde) usually used in cytopathology processing at initial stages as fixative have virucidal activity.[22] Based on the aforementioned, SARS-CoV-2 in any specimen processed with routine fixatives in cytopathology should be inactivated [Table 5].[22,29]
The data presented thus far suggest that the susceptibility to infection follows the bell curve, with an increase in the severity of the disease with the higher mortality in members of the population over 50 years.[30,31] This observation should be considered while organizing cytology laboratory services, namely, the potential effect on the personnel associated with various cytology services in regard to their potential for SARS-CoV-2 exposure.
A summary of recommendations for procedure specific protocols in routine cytopathology is enumerated in Table 6. These guidelines are recommended in addition to the WHO basic protective measures at a personal level [Table 2].[16] The virus survives on various plastic/metal surfaces, cardboards, disposable gowns, and paper surfaces for a significant amount of time [Table 5].[18,19,21,22,38] To avoid dissemination of the virus, it is recommended that on-site adequacy services should be canceled or postponed during the pandemic. In case a particular procedure is deemed necessary to be performed, the on-site personnel should follow the guidelines generated based on the information discussed in this review and summarized in Table 6.
Category/procedure | Measure(s) recommended *** |
---|---|
General cytopathology division | Routine standard precautions [Table 1].[14,15] In the case of SARS-CoV-2 suspected or known case-avoid exposure to older personnel over 60 years and personnel with compromised immunity. |
Cytoprep laboratory | Routine standard precautions [Table 1].[14,15] In cases suspected or positive for SARS-CoV-2 virus-perform the processing in certified Class II[35]Biological Safety Cabinet |
FNAB procedure | To minimize the risk of exposure with rapid dissemination of the virus, the “on-site adequacy evaluation services” may be suspended during COVID 19 pandemic related suspension of elective procedures.
** However, if FNAB has to be performed without on-site adequacy evaluation:
|
EUS-FNA procedure | Same guidelines as for “#3 FNAB procedure” with extra precaution, because the endoscopes travel through anatomical sites with the highest proportion of viruses in potentially positive cases, especially asymptomatic ones. |
Respiratory specimens such as bronchoalveolar lavage, bronchial lavage, bronchial brush, tracheal brush, sputum, and others such as rare percutaneous sampling of lung lesions | Routine Standard precautions [Table 1].[14,15] In cases suspected or positive for SARS-CoV-2 virus-perform the processing in certified Class II[35] Biological Safety Cabinet. |
Other body fluids such as peritoneal, pleural, pericardial, and other fluids (with potential positivity considered to be similar to blood positivity for SARS-CoV-2 virus) except urine | Routine Standard precautions [Table 1].[14,15] In cases suspected or positive for SARS-CoV-2 virus-perform the processing in certified Class II[35]Biological Safety Cabinet. |
Cell-block | Routine Standard precautions [Table 1].[14,15] In cases suspected or positive for SARS-CoV-2 virus-perform the processing in certified Class II[35]Biological Safety Cabinet Fix the cell-block for at least 2 h (for 2–3 mm thick cell-block material, formalin diffuses at the rate of 1 mm/h and 10% formalin (3.7% formaldehyde) would inactivate the virus in the interior of the cell- block). Most of the lab protocols require more than 6 h (up to 72 h) fixation.[29] |
All specimens received in 10% formalin and alcoholic fixatives | Routine Standard precautions [Table 1].[14,15]Concerning the surfaces of transport containers and paperwork, etc. In cases suspected or positive for SARS-CoV-2 virus-perform the processing in certified Class II[35]Biological Safety Cabinet. |
Splitting of specimens | Depending on individual institutional/laboratory protocols, some labs may split the specimen between various subspecialty labs. In such cases, the microbiology lab should split the specimen under microbiology precautions and send most of the specimen to the cytopathology lab for further processing. |
Acknowledgments
The authors would like to thank Preeti N. Malani, MD, MSJ, (Chief Health Officer and a Professor of Medicine in the Division of Infectious Diseases, Associate Editor of the Journal of the American Medical Association [JAMA], University of Michigan, Ann Arbor, MI, USA) and Hossein Salimnia, Ph.D., (Professor, Division of Microbiology, Department of Pathology, Detroit Medical Center, Detroit, MI, USA) for the scientific review of the draft of this editorial.
We also thank Amy Conners, MS, CT (ASCP); Anjani Shidham, BS; Inderpreet Dhillon, MS, CT (ASCP); Anushree Shidham, BS; Ahmed Noorsaeed, MD (Cytopathology fellow); Aditya Shidham, MS; and Kathy Rost, Administrative Assistant, for their critical input in scientific draft editing. Their participation in improving this article is greatly appreciated.
The authors also thank “Webpage capture – Archive-today” https://archive.is/to archive some of the web references for permanent archival so that their original links may be inactive in the future.
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COMPETING INTERESTS STATEMENT BY ALL AUTHORS
The authors declare that they have no competing interests.
AUTHORSHIP STATEMENT BY ALL AUTHORS
All authors of this article declare that we qualify for authorship as defined by ICMJE http://www.icmje.org/#author. Each author has participated sufficiently in the work and takes public responsibility for appropriate portions of the content of this article. VS conceived the idea, conducted literature review, and wrote the manuscript. All (VS, NF, and LL) critically reviewed the article. All authors read and approved the final manuscript.
LIST OF ABBREVIATIONS (IN ALPHABETIC ORDER)
BSC: Biological safety cabinet
BSL-2: Biosafety level 2
CCV: Canine coronavirus
CDC: Centers for Disease Control and Prevention
COVID-19: Coronavirus Disease 2019
CT: Computerized tomography
D: day(s)
FNAB: Fine needle aspiration biopsy
H: hours(s)
HcoV: Human coronavirus
MERS-CoV: Middle East Respiratory Syndrome Coronavirus
MHV: Mouse hepatitis virus
min: minute(s)
PCR: polymerase chain reaction
PPE: Personal protective equipment
rRT-PCR: Real-time reverse transcriptase–PCR
s: second(s)
SARS-CoV: Severe Acute Respiratory Syndrome Coronavirus
SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2
TGEV: transmissible gastroenteritis virus
WHO: World Health Organization
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