Maintaining good oral health is an integral part of human health. However, at present, oral cancer is one of the most critical health issues. This cancer is the sixth most common cancer worldwide, and every year, half a million people are diagnosed with this type of cancer. It is prevalent in areas where betel quid chewing, smoking, and alcohol drinking are observed in high frequency. Forty percent of cancer cases in Southeast Asia refer to oral cancer [1]. Cancer develops in the anterior tongue, gingival, buccal cavity, retromolar trigone, hard palate, salivary glands, and even tonsil glands [2]. Primarily, oral cancer arises as a lesion that is hyperplastic in growth. Due to external carcinogenic stimuli and the absence of internal cell regulations mechanism because of tumor repressor genes, the hyperplasia turns into metaplasia and anaplasia, leading to malignant invasion. Oral infection caused by the Herpes virus, Human Papillomavirus, Candida albicans, Treponema pallidum, and even poor oral hygiene can also be a factor that increases the risk of oral cancer [3].

In Bangladesh, the rate of oral cancer is high. A study revealed that cancer cases are approximately 200,000 per year and among them, oral cancer represents 20%, and it is the third leading cancer occurring in this country [4]. A study also showed that 7000 people in Bangladesh are diagnosed with oral cavity cancer every year and among them, 6.6% without feasible cure. The majority of oral cancer patients are from rural areas of Bangladesh [5]. The main causes of oral cancer in Bangladesh are tobacco, betel leaf, catechu, alcohol, and smoking. At the same time, arsenic-contaminated groundwater, availability of chemical carcinogens, mainly formalin-treated fruits, and poor hygiene conditions increase the risks of oral cancer in Bangladesh.

Despite significant development in oral cancer treatment, cancer patients remain at risk of developing severe infections. The immune-compromised patients are susceptible to infections by drug-resistant opportunistic microbes like Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella, E. coli. This infection may occur during the cancer progressions or after surgery [6]. The infection decreases the recovery rate of patients and it also increases the mortality rate. Due to this infection, cancer also spreads to the other parts of the body. After chemotherapy and radiotherapy treatment, the cancer patients become more immune-suppressed and thus reduce the number of white blood cells [7]. The lower level of neutropenia due to this radiotherapy increases the possibility of infectious disease. Significant parameters are involved in oral cancer’s etiology, such as age, gender, food habit, race, tobacco use, and alcohol consumption.

For treating infected oral cancer patients, all kinds of antibiotics can be used. Many antibiotics are resistant to both gram-positive and gram-negative bacteria. Sometimes a mixture of antibiotics is used for better treatment. The antibiotics generally used are cephalosporins, aminoglycosides, quinolones, carbapenems, penicillin, and several other antibiotic classes [8]. Antibiotics for which millions of lives have been saved in the past are now less effective against many bacterial infections. The antibiotic resistance crisis is increasing day by day because of the overuse and misuse of these medications. Again, now the microbes are no longer susceptible to the commonly used antibiotics. By the process of mutation, the bacteria can evade the effect of the antibiotics. Through the process of natural selection, those bacteria may carry on and pass the resistant genes into the remaining gene pool [9].

Study populations, place, and duration: The study involved the collection of both data through a questionnaire and a swab sample from the oral cavity. Data and swab samples were collected from 55 oral cancer patients taking treatment from the National Institute of Cancer Research and Hospital, Dhaka, Bangladesh, from August 2019 to February 2020. The clinical samples were checked for the presence of infection on their cancer site. Another control group of 50 people was set with healthy volunteers aged over 22 who did not exhibit any cancer signs (Figure 1).

According to the guidelines provided by the Clinical Laboratory Standard Institute (CLSI), the antibiotic susceptibility pattern of the isolates was examined using the disc diffusion method [10] [11]. The isolates’ 22 hours new culture (Pseudomonas spp., Klebsiella spp., Escherichia coli and Proteus spp., Staphylococcus spp., Streptococcus spp., Enterococcus spp.) were adjusted to the turbidity of 1 McFarland standards and bacterial suspensions were spread over Mueller-Hinton agar (MHA). The antibiotic disc used in the study for gram-positive bacteria included amikacin, gentamicin, Imipenem, ceftazidime, amoxicillin, erythromycin, chloramphenicol, linezolid, ciprofloxacin, nalidixic acid, oxacillin, cloxacillin, and metronidazole (oxoid). Moreover, for gram-negative bacteria, antibiotics involved were amikacin, gentamicin, Imipenem, Ceftriaxone, vancomycin, azithromycin, amoxicillin, penicillin-G, amoxiclav, ciprofloxacin, nalidixic acid, tetracycline, and metronidazole (oxoid). The plates were incubated at 37˚C for 18 - 20 hours and the zone of inhibitions was measured (mm).