An outbreak of a pandrug-resistant nosocomial pathogen was interrupted by not using hospital sinks during COVID, according to Basma Mnif, Professor of Microbiology at Habib Bourguiba University Hospital of Sfax, Tunisia. In her presentation at the 14th SAFHE Southern African Healthcare Conference, she said that infection control methods to eradicate the pathogen failed and that other research indicated it was necessary to replace the sinks entirely.
Multidrug-resistant organisms (MDRO) are a growing threat in hospitals, especially to critically ill patients.
Over 2017 to 2021, 90 critically ICU patients in a Tunisian hospital were infected with pandrug-resistant Proteus mirabilis strains. This is the first known long-term outbreak by pandrug-resistant P. mirabilis strains.
P. mirabilis is an uncommon nosocomial pathogen causing opportunistic infections. P. mirabilis survives well in the natural environment and is increasingly implicated in nosocomial outbreaks worldwide.
The all-cause mortality rate in the infected was 47%, with patients ranging in age from 16 to 78 years. The average length of stay before infection was 23.56 days.
An outbreak was recognised in April 2017, and IDC measures were taken to contain it. The outbreak was suppressed but reoccurred in July and December. Analysis revealed overlapping ICU stays of infected patients, suggesting horizontal, intra-ICU transmission. Lab analysis of phenotypes revealed two clones, A and B, both with drug resistance genes, to which a third clone was added in 2018. This Clone C proved to have resistance to all known antibiotics.
During the COVID pandemic in 2020, hospital sinks were not used and enhanced infection prevention interventions were deployed. This period coincided with a complete absence of P. mirabilis infections. The outbreak resumed in 2021, with the same three clones causing infections in patients.
“The outbreak intermission during COVID could be related to the enhanced protection measures implemented during this period,” Prof Mnif noted, “but we think that the sinks are in fact the reservoirs of these MDRO, and must in fact be removed and replaced, and the chemical disinfection that we had performed was not sufficient to control the outbreak.”
The outbreak highlighted the need for proper infection control protocols. Hospital wastewater is a major source of outbreaks, Prof Mnif pointed out. A study found that “over the past 20 years, there have been 32 reports of carbapenem-resistant organisms in the hospital water environment.”
She said when it came to replacing the sinks, hospitals should “respect FGI guidelines, especially in having sufficient depths of the sink, deep enough to prevent splashing.” Having sufficient pressure and splash reduction measures such as splash guards are also important, Prof Mnif added.
Although there are CDC guidelines to help prevent colonisation, there is no clear strategy for eradication for when a sink is colonised. There is likely genetic interchange between organisms in biofilms, something which needs to be investigated further, as well as means of eradication.
