Detection of aerobic gram negative bacteria and bacterial endotoxins from the oral cavities of patients on cancer therapy
Date
2017
Authors
Mathews, Juliana Susan
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Abstract
Chemotherapy and radiation therapy are the most widely used interventions for the treatment
of cancer. Several adverse effects including mucositis are associated with these therapies,
which affect a patient’s quality of life, resulting in morbidity and mortality. Cancer therapy
also causes an imbalance in the oral flora which allows colonization of the oral cavity with
uncommon bacteria, including aerobic gram negative bacteria and less commonly, Candida.
These organisms can become established in the lesions of oral mucositis. These gram
negative bacteria produce endotoxins. Although the involvement of endotoxins in the
development of systemic infections is well described, the role of endotoxins in oral mucositis
is not known. Therefore, this study investigated the presence of aerobic gram negative
bacteria and endotoxins in the oral cavities of patients receiving cancer treatment and their
role in the development of oral mucositis.
Oral cavity rinse samples were collected from 100 cancer patients on cancer treatment and 50
healthy individuals. Ethical clearance was obtained from The Committee for Research on
Human Subjects (Medical). The demographic and clinical data were recorded. Samples were
serially diluted and cultured onto Mitis Salivarius Agar for Streptococci, Baird Parker Agar
for Staphylococcus aureus, MacConkey Agar for aerobic gram negative bacteria (AGNB)
and Chromagar for Candida species. Colony counts were obtained and the cultures of AGNB
and Candida species were further identified at the species level using the API technique. An
antimicrobial susceptibility test was performed on AGNB. Oral rinse samples were further
tested for the presence of endotoxin using the Hycult Biotech Limulus Amebocyte Lysate
(LAL) assay. Results were analysed using the Mann-Whitney and chi-square test. P-values of
≤ 0.05% were considered significant.
Eighty percent of cancer patients were females with breast (58%) or cervical cancer (9%).
The majority of these patients were on chemotherapy (61%), were receiving a combination of
chemotherapeutic drugs and had completed many cycles of chemotherapy treatment. Twelve
percent of patients had oral mucositis of various grades. Healthy individuals also comprised
of mainly females (76%). All cancer patients and 98% of healthy individuals carried
Streptococci. No significant difference in the carriage of S. aureus was found between the
two groups. However, the Candida carrier rate was significantly high in cancer patients
(55%) compared to the healthy (20%) individuals (p<0.01). Although the Candida counts
were not different between the groups (p>0.05), cancer patients carried a variety of Candida
species and some patients carried more than one type of Candida species in their oral cavity.
In addition, C. glabrata was only found in cancer patients. Between the groups of cancer
patients and healthy individuals, no significant difference in the carrier rate of AGNB was
found (cancer 24% vs 14% healthy). However, cancer patients carried a variety of AGNB.
Enterobacter cloacae and Klebsiella pneumonia was isolated from the oral cavities of both
the study groups. These bacteria were resistant to many antibiotics. When the prevalence of
these oral bacteria was compared between patients with and without oral mucositis, it was
found that the percentage prevalence of Candida species was significantly high in patients
with oral mucositis.
A mean endotoxin concentration of 3.65ng/ml and 3.37ng/ml was detected in the oral rinse
samples of cancer patients and healthy individuals respectively. The difference in the
endotoxin between the two groups was not significant (p=0.5). Mean values of 4.1ng/ml and
3.53ng/ml were found in cancer patients with and without oral mucositis respectively. The
difference in the quantities of endotoxins between the two groups was not significant (p=0.6).
In addition, endotoxin present in cancer patients with AGNB (3.39ng/ml) and without AGNB
(3.8ng/ml) was also not significantly different.
These results suggest that although cancer patients carry aerobic gram negative bacteria and
endotoxins in their oral cavities, they may not contribute in the exacerbation of oral
mucositis. However, Candida species may contribute in the exacerbation of oral mucositis
and therefore, during cancer treatment, it is important to take preventative measures to reduce
the colonization of Candida to prevent infection.
Description
A research report submitted to the faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in the partial fulfillment of the requirements for the
Degree of Master of Science in Dentistry,
Johannesburg, 2017