Food Protection Trends - March/April 2021 - 195

Abimbola Allison and Aliyar Cyrus Fouladkhah*
Public Health Microbiology Laboratory, Tennessee State University,
Nashville, TN 37209, USA

PEER-REVIEWED ARTICLE
Food Protection Trends, Vol. 41, No. 2, p. 195-203
Copyright© 2021, International Association for Food Protection
2900 100th Street, Suite 309, Des Moines, IA 50322-3855

Sensitivity of Planktonic Cells and Biofilm of
Wild-Type and Pressure-Stressed Cronobacter sakazakii
and Salmonella enterica Serovars to Sodium Hypochlorite
ABSTRACT
Aggregate cells are the predominant physiological mode
of bacterial proliferation in food processing areas and
clinical settings, and microbial biofilms are responsible
for the vast majority of all bacterial infections. The
current study was conducted to determine whether
sodium hypochlorite, validated in the past against
planktonic cells, is also efficacious for decontamination of
biofilms of wild-type and pressure-stressed nontyphoidal
Salmonella enterica serovars and Cronobacter sakazakii.
A four-strain mixture of wild-type and pressure-stressed
pathogens was used for biofilm formation of up to 14
days on the surface of stainless steel coupons at 7 and
25°C. Experiments were conducted in two biologically
independent repetitions (blocking factors) in a randomized
complete block design. Similar biofilm formation trends
were observed for wild-type and pressure-stressed
phenotypes of C. sakazakii. Treatment with sodium
hypochlorite was efficacious (P < 0.05) only against the
planktonic cells and was unable to completely eliminate
1- and 2-week-mature bacterial biofilms of the pathogens.

These findings illustrate that, whereas after a typical
sanitization with sodium hypochlorite up to >3-log
reduction of planktonic pathogens is achievable, >6 log
of viable pathogens per cm2 of an abiotic surface may
survive if bacteria had the opportunity to anchor onto the
surface and form biofilm prior to treatment.

INTRODUCTION
As one of the leading causes of foodborne bacterial
infections in American adults, various nontyphoidal
Salmonella enterica serovars are an important public health
microbiology challenge. Various nontyphoidal serovars of the
pathogen are the leading cause of foodborne hospitalizations
and death episodes in the United States. In a typical year,
over one million Americans are estimated to contract
salmonellosis, with 27.2 and 0.5% hospitalization and death
rates, respectively (10, 26). This burden is expected to be
augmented in the landscape of changing climate because
every 1°C increase in environmental temperature above
5°C could be associated with a 5 to 10% annual increase
in cases of salmonellosis (13). The bacterium is also the

*Author for correspondence: Phone: +1 970.690.7392; Email: afouladk@tnstate.edu

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