Beware false negative PCR tests, warns Groote Schuur doctor

Organisation: Position: Deadline Date: Location:

Clinicians should be wary of false negative COVID-19 PCR swab tests and rather rely on typical infection symptoms, backed by radiological scans. This warning came from Groote Schuur Hospital’s medical team leader, Professor Graeme Meintjes, whose team is at the vanguard of the country’s C-19 hospitalisations, caring for 180 patients as of the middle of last week, a number expected to double over the next fortnight in our worst-affected province. The Western Cape carries double the country’s entire infection and recorded mortality burden, the comparisons arguably skewed by its more efficient provincial testing and tracing, and proficient C-19 cause-of-death methodology.

The webinar, held on Thursday evening last week, (11 June), was part of a series hosted by Discovery in conjunction with Medical Brief, the Desmond Tutu HIV Foundation, the SA Medical Association, the SA Private Practitioners Forum and the Unity Forum for Family Practitioners. The session was facilitated by Professor Linda-Gail Bekker, the deputy director of the Desmond Tutu HIV Centre at the Institute of Infectious Diseases and Molecular Medicine at University of Cape Town (UCT), and introduced by Dr Maurice Goodman, chief medical officer at Discovery Health.

Prof Meintjes gave an example of one male patient who was persistently hypoxic, having had two negative nasal swabs, and being treated with antibiotics. However, his CT scan was highly suggestive of C-19 and the diagnosis was made based on the clinical and radiological picture.

“You’ll see this around the country,” he warned more than 1,600 colleagues attending the webinar.

Sharing his freshly-acquired knowledge on all aspects of C-19 patient care, symptoms and co-morbidities, Prof Meintjes said another challenge was deciding on the timing of intubation and ventilation of patients.

Some, especially those with profound hypoxia did well on oxygen, even in spite of a high respiratory rate, and his team used high flow nasal oxygen, (HFNO) in preference over ventilation, (where possible), the latter nearly always resulting in death.

He said another challenging decision was whether to transfer C-19 patients from peripheral hospitals to tertiaries, while he and his staff struggled upon seeing relatives and close friends unable to visit an isolated and dying loved-one. Some of his staff had become infected, impacting morale and disrupting services, creating a major organisational challenge around traditional ways of balancing competing medical and surgical priorities.

He revealed that COVID-19 patients with diabetes and/or obesity were three times more likely to die than those who were HIV positive, whether the latter were on anti-retroviral drugs or not, arguably evoking a sigh of relief among his colleagues, many of whom bore the brunt of the Aids epidemic. Prof Meintjes said HIV-positive patients represented just over a two-fold higher C-19 infection risk than those without any other co-morbidities – a relatively low contributor to serious C-19 symptoms.

“There’s no difference between patients with suppressed viral load and those not on ART. It may be socio economic factors. HIV is associated with increased COVID risk, but what we’re seeing is probably lower than the cited figure of 2,7 times greater risk. While the obesity data are not available, we can see it’s a big contributor, especially when there’s accompanying high blood pressure. About half our C-19 deaths can be attributed to diabetes, but only 12% to HIV,” he revealed

A health advisor to the department of science and technology and the country’s research chair in poverty-related infections, Prof Meintjes is also deputy head of the department of medicine at UCT. He said that as of 11th June, there were 36,000 people in the Western Cape diagnosed with C-19 and 900 deaths. Tourism, the life-blood of the province’s economy, is believed responsible for multiple seeding of the virus by overseas visitors. Groote Schuur Hospital serves four of the heavy-burden sub-districts of the Cape Metropole.

He said the first C-19 patient was admitted to GSH wards on 18 March and there’d been a gradual increase though March and April, escalating dramatically over the past few weeks.

“The first few weeks gave us an opportunity to prepare; psychologically, communications-wise, agree on a plan for the redeployment of staff, and to rapidly scale up. We now have isolation rooms and six wards set aside for those under investigation, including the maternity and psyche wards,” Prof Meintjes said.

About 25% of deaths in the Western Cape were people in their 50’s and another 25% those in their 60’s, with the percentages climbing, the older patients were.

Serious co-morbidities nearly always contributed to the far lesser mortalities in younger age groups. C-19 affected males more severely than females with the biggest risk factors being uncontrolled diabetes, obesity, hypertension, and cardio-vascular and pulmonary disease. About 5% of all their admissions required ICU treatment.

Asked how common pulmonary emoboli were, Prof Meintjes said about 25% of patients at the severe end of the C-19 spectrum were shown to have them and/or deep vein thrombosis, with an increased mortality risk of 22 to 33%.

His team’s early experience was that high-flow nasal oxygen, (HFNO), had a 31% survival rate with 55% of serious patients intubated. Of those who failed on HFNO and then required ventilation, there had been no survivors – all had either died or were still on ventilators.

Answering a question on duration of HFNO, Prof Meintjes said the timing varied according to individual patients.

“Some we’ve been able to consider weaning after three days and some stay on for two weeks. For those on HFNO for 10 days or longer, we worry about pneumonia and so we do radiology and start them on steroids,” he added.

Prof Meintjes strongly promoted ‘awake-proning,’ (the turning of patients onto their stomachs for two hours or longer, if they can tolerate it), where gravity allows blood to settle in the anterior part of the lungs, providing better oxygenation in two thirds of patients, according to studies. He said oxygen saturation when doing this increased by up to 20%, dramatically increasing a patient’s chances of survival. However, he warned against doing this for severely restless or disoriented patients as they could easily turn onto their backs.

Asked about the use of extracorporeal membrane oxygenation, (ECMO), he said this was in the domain of his critical care colleagues, however it would only be considered in very select patients, especially those with single organ failure (not multiple). ECMO provides temporary support for patients with cardiac or pulmonary failure.

Thanking Prof Meintjes on behalf of webinar participants, Prof Bekker said he cut his teeth on the HIV/Aids epidemic, which probably helped him prepare for the COVID-19 pandemic. He and his courageous colleagues were at the coalface of the coronavirus pandemic daily, serving at both Khayelitsha and Groote Schuur hospitals, risking their wellbeing in service of others and paving the way for the rest of the country, still bracing itself for a surge of C-19 admissions.

Once uploaded to the Discovery site, the Prof Meintjes webinar can be found here


Receive Medical Brief's free weekly e-newsletter



Related Posts

Thank you for subscribing to MedicalBrief


MedicalBrief is Africa’s premier medical news and research weekly newsletter. MedicalBrief is published every Thursday and delivered free of charge by email to over 33 000 health professionals.

Please consider completing the form below. The information you supply is optional and will only be used to compile a demographic profile of our subscribers. Your personal details will never be shared with a third party.


Thank you for taking the time to complete the form.