The oral cavity has various fundamental functions besides playing an important role in ingesting, speaking and breathing; it is an entry from external environment to the gastrointestinal tract and the human immune system. In healthy person, oral microorganisms and the host immune system are in ecological equilibrium, which is a premise for sustaining a barrier against ingested pathogens. Odontogenic infections can spread either locally causing cellulites and abscess formation or by dissemination causing distant site infections. Disease of the pulp and periodontium such as dental caries, endodontic infections, dental abscess, periodontitis and pericoronitis which constitute the vast proportion of odontogenic infections are mainly caused by the endogenous bacterial microflora in the oral cavity.1 There are more than 500 distinct bacterial species which have been known to constitute the normal oral microflora. The major etiological factor for odontogenic infection is the normal bacterial flora in the plaque. The first line of treatment for majority of orofacial infections is debridement and or incision and drainage but in some cases extraction of the offending tooth is also required. Most of the microorganisms causing orofacial infections are treated by using drugs like β-lactum antibiotics, cephalosporins, fluoroquinolone, aminoglycosides, macrolides & other broad spectrum antibiotics.2

A prospective study was conducted between the period of October 2017 to September 2018. The study was conducted in Department of Dentistry at Venkateshwara Institute of Medical Sciences, Gajraula, India. 180 patients diagnosed for having orofacial infections of odontogenic origin were selected randomly from the Department of Dentistry, VIMS, Gajraula after obtaining ethical clearance. Patients with isolated or multiple orofacial infections of all age groups and gender were included in the study. After taking detailed history, each patient was thoroughly examined. The pus was collected from the involved space. Pus was collected by aspirating abscess using sterile 18 gauze disposable needles with 5 ml disposable syringes intraorally or extraorally maintaining asepsis. Sample was also collected on swab sticks, following all the aseptic precautions including irrigation with 0.2% chlorehexidine for intraoral sites and the skin cleaned with Povidone iodine 5% solution and alcohol for extraoral sites. The samples were brought to the Labs, VIMS; laboratory at the earliest (within 1 hr). The pus sample received was divided into two parts. One part was inoculated into glucose broth medium for aerobic bacteria and second part was inoculated into Robertson’s cooked meat broth medium or using gas pack for anaerobic bacteria. The pus sample obtained was subjected to gram staining, aerobic culture, anaerobic culture and antimicrobial susceptibility testing (if the culture was positive). For aerobic culture, the samples were inoculated on Mac-Conkeys agar and Blood agar and incubated at 370C for 18-24 hrs. Growth was identified using appropriate biochemical tests. If growth does not occur after 48hrs of incubation, then it was considered as sterile. For anaerobic culture, sample was inoculated into plain blood agar, Mac-Conkey’s agar and Nutrient agar and incubated anaerobically at 370C, using gas pack, in anaerobic jar for 48-72 hrs. Strains of Pseudomonas aeruginosa were kept in anaerobic jar as a control. If growth does not occur after 72hrs of incubation, then it was considered as sterile. The antimicrobial susceptibility testing of all isolates was done by the standard disc diffusion method (Kirby Bauer method, 1966) using commercial discs. Table 1: Age wise distribution of patients Age in years Numbers Frequency 5 – 10 2 1.1 11 – 20 16 8.8 21 – 30 74 41.1 31 – 40 44 24.4 41 – 50 24 13.3 51 – 60 14 7.7 61 – 70 4 2.2 71 – 75 2 1.1 Table 2: Various bacteria found in the positive culture Name of organism Number % Aerobic organism Strepto. viridians 48 22.8 Pseudomonas aeruginosa 28 13.3 Staph. aureus 22 10.4 Klebsiella spp 20 9.5 CONS (Coagulase Negative Staphylococcus) 14 6.6 Anaerobic organism Peptostreptococcus 78 37.2 Table 3: Antibiotic susceptibility pattern among Gram positive aerobic organism S No. Antibiotics Sensitive % Resistant % 1 Amoxycillin 72 85.7 12 14.2 2 Amoxyclav 84 100 0 0 3 Cefoxitin 84 100 0 0 4 Chloramphenicol 80 95.2 4 4.7 5 Clindamycin 81 96.4 3 3.5 6 Erythromycin 78 92.8 6 7.1 7 Levofloxacin 75 89.2 9 10.7 8 Linezolid 84 100 0 0 9 Vancomycin 84 100 0 0 10 HLAR (High Level Aminoglycoside Resistance) 84 100 0 0 Table 4: Antibiotic susceptibility pattern among Gram negative aerobic organism S. No. Antibiotics Sensitive % Resistant % 1 Amikacin 40 87.5 8 12.5 2 Amoxiclav 48 100 0 0 3 Colistin 48 100 0 0 4 Cefoperaxone 48 100 0 0 5 Ceftazidime 45 93.7 3 6.3 6 Gentamicin 44 91.6 4 8.3 7 Ciprofloxacin 42 83.3 6 16.6 8 Imipenem 48 100 0 0 9 Piperacillin+Tazobactum 48 100 0 0 Table 5: Antibiotic susceptibility pattern among Anaerobic organism S. no Antibiotics Sensitive % Resistance % 1 Ampicillin 70 89.7 8 10.2 2 Amoxiclav 78 100 0 0 3 Clindamycin 74 94.8 4 5.1 4 Imipenem 78 100 0 0 5 Metronidazole 78 100 0 0 6 Piperacillin+Tazobactum 78 100 0 0

In this study 180 patients with orofacial infection of odontogenic origin were considered. The minimum age of male patients was 8 yrs. and maximum age was 75 yrs. The minimum age of female was 15 yrs. and maximum age was 75 yrs. The most common age group involved was 21-30 yrs. in both male and female. The most frequent source of infection was infected mandibular third molar (48.2%) followed by maxillary third molar (29.4%). Submandibular space was most commonly involved in 91 cases followed by Buccal space in 66 cases. Pain was the most common symptoms in all the cases (100%) followed by swelling (58.8%), trismus (30.5) and dysphagia (10.5%). Streptococcus viridians (22.8%) were the most frequent aerobic bacterial isolate and among anaerobes Peptostreptococcus were the major pathogen isolated. All aerobic gram positive microorganisms were highly sensitive (100%) to Amoxyclav, Cefoxitin, Linezolid, Vancomycin and HLAR. Resistance was maximum to Amoxycillin (14.2%) followed by Levofloxacin (10.7%). All the Gramnegative aerobic isolates were completely susceptible (100%) to Amoxiclav, Colistin, Cefoperaxone, Imipenem and Piperacillin+Tazobactum. Maximum resistance was seen to Ciprofloxacin (16.6%) followed by amikacin (12.5%). All the anaerobic organism were 100% sensitive to Amoxiclav, Imipenem, Metronidazole, Piperacillin + Tazobactum. Maximum resistance was seen to Ampicillin (10.2%).

Maximum number of cases of orofacial infection of odontogenic origin were seen in the age group of 21-30 yrs. 41.1% (74/180) followed by 24.4% (44/180) of cases belong to the age group of 31-40 yrs. Our study correlates with the study done by Patankar et al3 who have reported 21-30 yrs. of age group as the most commonly affected age group. In the present study pain was more or less consistently present in all cases of orofacial infection of odontogenic origin which was consistent with the finding of G.C. Mathew et al4 who reported pain to be 97.1%. In the present study, 210 microorganisms were isolated in all 180 pus samples. Out of 210 isolates, Gram positive cocci were found in 162 (77.2%) isolates and Gram negative bacilli were found in 48 (22.8%) isolates which correlates with studies of Mahalle et al5, Fating NS et al6, and Rega AJ et al.7 In our study total 132 strains of aerobic bacteria were isolated. The most predominant isolate was Strepto. viridans (36.36%). This finding was in concordances with the study carried out by Santosh et al (36.4%)8 and R. Bahl et al (45%).9 The percentage of isolation of Strepto. viridans was less in our study as compare to the studies done by N S Fating et al (70%)(6) and Chunduri etal et al (64%).10 A total of 78 strains of anaerobic bacteria were isolated in our study. Among anaerobes Peptostreptococcus was the predominant strain isolated (37.2%). This finding was in concordances with the studies of Santosh et al (41.1%)8, Patankar et al (48%)3 and Chundurie et al (26%).10 In the present study Mandibular 3rd Molar tooth (48.2%) was the most commonly affected tooth which was also reported by R. Bahl et al9, NS Fating et al6, and V. Yuvaraj et al.11 In the present study the most common site of orofacial odontogenic infection was submandibular space (50.5%) followed by Buccal space (36.6%) which correlated with the study of G. C. Mathew et al4 who reported submandibular space infection in 69.3% of cases and buccal space infection in 31.4% of cases. All strains of Gram Positive cocci were 100% sensitive to Amoxyclav, Cefoxitin, Linezolid, Vancomycin, HLAR (High Level Aminoglycoside resistances). All strains of gram negative isolates were 100% sensitive to Amoxiclav, Colistin, Cefoperazone, Imipenem and Piperacillin + Tazobactum, 93.7% were sensitive to Ceftazidime and 91.6% were sensitive to Gentamicin. All the anaerobic organism were 100% sensitive to Amoxiclav, Imipenem, Metronidazole and Piperacillin + Tazobactum. All these findings correlates with the findings of Mahalle et al.5

Infections originating from teeth or their supporting structures known as odontogenic infections have been one of the most common diseases in the oral and maxillofacial region especially in developing countries. The purpose of this study was to identify microbial flora present in orofacial space infection of odontogenic origin and thereby provide better perspective in management of odontogenic infection. The antibiotic susceptibility test results shows that there was an increasing resistance towards penicillin groups of drug and quinolones group of drugs. Amoxiclav, Imipenem and cephalosporins was found to have excellent in-vitro activity against both Gram positive and Gram negative organisms. Therefore with odontogenic infections it is always appropriate to begin with the empiric antibiotic regimen with correlation to clinical presentation thinking of the most likely suspected microorganisms involved in the infections, which are usually the normal flora of the region, without forgetting the importance of early surgical intervention to reduce morbidity and complications.

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