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 ~  Abstract
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 ~  Results
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Year : 2003  |  Volume : 21  |  Issue : 2  |  Page : 111-114

Microbial flora in orodental infections

Department of Microbiology, Pt. BD Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana - 124 001, India

Correspondence Address:
Department of Microbiology, Pt. BD Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana - 124 001, India

 ~ Abstract 

The present study was carried out to compare the normal aerobic and anaerobic bacterial oral flora with flora from deep seated dental caries, gingivitis and adult periodontitis. All the samples belonging to both the control and study groups yielded microbes. Aerobe / Anaerobe ratio was high in normal flora (1.48) as compared to dental caries (0.9), gingivitis (0.72) and periodontitis (0.56). Ninety seven percent of orodental infections were polymicrobial and three or more microbes were found in 84% cases of study group as compared to 28% in controls. Streptococcus mutans and anaerobic lactobacilli were common in dental caries, Actinomyces and Peptostreptococcus spp. in gingivitis, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in periodontitis.

How to cite this article:
Saini S, Aparna, Gupta N, Mahajan A, Arora D R. Microbial flora in orodental infections. Indian J Med Microbiol 2003;21:111-4

How to cite this URL:
Saini S, Aparna, Gupta N, Mahajan A, Arora D R. Microbial flora in orodental infections. Indian J Med Microbiol [serial online] 2003 [cited 2020 Sep 21];21:111-4. Available from:

Dental caries and periodontal disease i.e. gingivitis and periodontitis are the most common chronic oral diseases in the world. Although these diseases have affected human beings since prehistorical times, the prevalence of these diseases has greatly increased in modern times. At present, the prevalence of dental caries in India is approximately 60-65%[1],[2] while the prevalence of periodontal disease is approximately 65-100%.[3] Dental caries is an infectious microbial disease that results in localised dissolution and destruction of the calcified tissues of the teeth.[4] So far, establishing a cause and effect relationship between a single microorganism in oral flora and caries has been very difficult. Most of the investigators believe that development of caries of enamel is preceded by the formation of microbial plaque in the tooth.[5],[6]
Gingivitis and periodontitis are chronic bacterial infections. As in other infections, the host bacterial interactions determine the nature and extent of the resulting disease. Pathogenic microorganisms may cause disease indirectly by stimulating a host response or directly by producing toxins and invading the tissues. Overwhelming evidences now show that organisms present in microbial plaque constitute the primary and possibly the only, extrinsic etiologic agent participating in the causation of gingivitis and periodontitis.[7]
Systematic studies on the anaerobic bacterial flora of orodental infections reported from India are few and none from Haryana. Thus this study was undertaken to isolate and identify aerobic as well as anaerobic microbes from patients of adult periodontitis, gingivitis and deep seated dental caries and compare the findings against normal healthy individuals.

 ~ Materials and Methods Top

The present study comprised of 100 cases. Twenty five cases constituted the control group and 25 cases each of dental caries, gingivitis and periodontitis were taken as study group. All cases were selected out of the patients attending the out patient department of Dental College, Rohtak.
The selection criteria for the control group was based on the absence of any orodental infection and any of the oral manifestations of any systemic disease. The study group was divided into three subgroups one each of dental caries, gingivitis and periodontitis on the basis of history and clinical examination of the patients.
In case of patients with dental caries, material from the carious teeth was excavated from the deeper layers with the help of a sterile excavator and was inoculated into Robertson's cooked meat broth (RCM) and incubated at 37C for 48 hours. For the control group and the cases of gingivitis and periodontitis the samples were collected with the help of a sterile absorbent paper point from the subgingival plaque, the gingival sulcus and the base of the pocket respectively.
For isolation of aerobic bacteria, subculture was made from top of RCM medium on blood agar and MacConkey agar and incubated at 37C for 24 hours. For isolation of microaerophiles, subculture was done on blood agar, chocolate agar and brain heart infusion agar and incubated under 5-10% carbon dioxide at 37C for 24-48 hours. Identification upto the species level was done on the basis of Gram staining, culture characteristics and biochemical reactions of the bacteria.[8] For isolation of anaerobes, subculture was made from RCM medium near meat particles on 5% sheep blood agar and brain heart infusion agar supplemented with vitamin K (0.1 g/mL) and haemin (1 g/mL) were used. Anaerobic cultivation was done in an anaerobic jar from which oxygen was removed and a mixture of 90 percent hydrogen and 10 percent carbon dioxide was introduced and incubated at 37C for 72 hours. Maintenance of anaerobiosis inside the jar was monitored with the help of a biological indicator (Pseudomonas aeruginosa) and a chemical indicator (methylene blue). Prevotella melaninogenica was included in each batch of cultures as the obligate anaerobic control. The anaerobic isolates so obtained were identified according to their Gram staining, culture characteristic and biochemical reactions.[8],[9]

 ~ Results Top

All the samples belonging to the study group as well as the control group yielded microbes. Out of 75 cases of orodental infections, 73 (97.3%) were polymicrobial (>1 isolate) as compared to 92 percent among controls. Three or more isolates were found in 63 (84%) cases of orodental infections as compared to only 7 (28%) cases among 25 controls [Table - 1].
The ratio of aerobes, facultative anaerobes to anaerobes decreased as the lesion progressed from normal gingiva (1.48) to dental caries (0.90) to gingivitis (0.72) to periodontitis (0.56). Maximum number of anaerobes were isolated from the cases of periodontitis (57). The number of organisms isolated per lesion in normal gingiva, dental caries, gingivitis and periodontitis was 2.28, 2.96, 3.16 and 3.56 respectively [Table - 1].
In the study group, the commonest aerobe isolated was  Streptococcus mutans  ental caries, Staphylococcus aureus   on gingivitis and  Actinobacillus actinomycetemcomitans  itans in periodontitis. Among the anaerobes, lactobacilli were the commonest in dental caries, Actinomyces in gingivitis and  Porphyromonas gingivalis  in periodontitis [Table - 2].

 ~ Discussion Top

Polymicrobial nature of the orodental infections has been brought out in this study. In our study, all the samples belonging to control as well as the study groups yielded microbes. Aerobes and facultative anaerobes were isolated from 100 percent and 96 percent cases of normal gingiva and orodental infections respectively. Anaerobes were isolated from 80 percent of the normal gingival samples and 97 percent of the cases of orodental infections. This rate of isolation of anaerobes was higher than the study of Chakraborti et al[10] who reported an incidence of 42 percent and 38.8 percent in cases of advanced adult periodontitis and normal gingiva respectively.
In this study, the ratio of aerobes and facultative anaerobe to anaerobes was 0.90, 0.72, 0.56 and 1.78 in cases of dental caries, gingivitis, periodontitis and normal gingiva respectively [Table - 1]. This depicted that aerobes and facultative anaerobes were more in normal gingiva while anaerobes predominated in orodental infections. Beena et al[11] concluded from their study on periodontal pathogens that, as the infection progresses, the proportion of anaerobes especially gram negative bacilli like Prevotella, Porphyromonas and Fusobacterium increases. Chakraborti et al[10] have reported a higher aerobes to anaerobes ratio of 2.38 and 2.84 in cases of advanced adult periodontitis and normal gingiva respectively. The various recovery rates of bacteria in different studies may be due to one of the following reasons - varying criteria of patient selection, differences in sites sampled and culture methods employed, geographically based differences and presence of the particular organism below the threshold of detection.
Our study shows that the flora in the normal gingiva was predominated by anaerobic gram positive cocci, of dental caries by anaerobic gram positive bacilli, of gingivitis by Actinomyces and black pigmented Bacteroides and that of periodontitis by gram negative bacilli, black pigmented Bacteroides, Fusobacterium and A. actinomycetemcomitans. S. sanguis predominated in normal gingiva where as S. mutans predominated in dental caries. Prevotella and Porphyromonas were absent in normal gingiva. Elevated levels of P. gingivalis and P. intermedia in active periodontal lesions support the view that these species have pathogenic potential and produce virulence factors playing an important role in periodontal breakdown. In our study, isolation of A. actinomycetemcomitans was 52% in cases of periodontitis as compared to 24% in control group. Antony et al[12] also reported a statistically significant difference in the isolation of A. actinomycetemcomitans among the patient group (55%) and the control group (22.5%). Saglie et al[13] stated that A. actinomycetemcomitans produces a large number of cytotoxic factors and has a high virulence potential which may permit the organism to invade and colonise the gingival connective tissue. Therefore, samples in cases of gingivitis and periodontitis must be screened for it.
Since the concept of dental infections has been bacteriologically non-specific and offers no rationale for antibacterial treatment, careful assessment and isolation of both aerobes and anaerobes is of utmost importance in the treatment of orodental infections. 

 ~ References Top

1.Shouri KL. Dental caries in Indian children. Indian J Med Res 1941;29:709-22.  Back to cited text no. 1    
2.Ramchandran K, Rajan BP, Shanmungan S. Epidemiological studies of dental disorders in Tamilnadu population, prevalence of dental caries and periodontal disease. J Indian Dent Assoc 1973;45:65-70.  Back to cited text no. 2    
3.Kanal M, Roy RK, Chawla TN, Kapoor KK, Kapoor DN. Gingivitis in the primary dentition among Lucknow urban and rural children. J Indian Dent Assoc 1971;43:709-13.  Back to cited text no. 3    
4.Ross PW, Holbrook WP. Dental plaque. In: Clinical and Oral Microbiology (Blackwell Scientific Publications, Glasgow) 1994:82.  Back to cited text no. 4    
5.Gibbons RJ, Socransky SS, Sawyer S, Kapsinialis B, Macdonald JB. The microbiota of the gingival crevice area of man: II. The predominant cultivable organisms. Arch Oral Biol 1963;8:281-9.  Back to cited text no. 5    
6.Darling AT. The pathology and prevention of caries. Br Dent J 1959;287:107-17.  Back to cited text no. 6    
7.Loe H, Theilade E, Jensen SB. Experimental gingivitis in man. J Periodontal 1965;36:177-87.  Back to cited text no. 7    
8.Koneman EW, Allen SD, Janda WM, Schreckenberger PC, Win WC Jr. Identification of Bacteria. In: Color Atlas and textbook of diagnostic microbiology, 4th ed. (J.P. Lippincott Co., Philadelphia),1992:419-668.  Back to cited text no. 8    
9.Brown R, Collee JG, Poxton IR. Bacteroides, Fusobacterium and other gram negative anaerobic rods; anaerobic cocci; identification of anaerobes. In: Mackie and McCartney's Practical Medical Microbiology, 14th ed. Colle JG, Fraser AG, Marmion BP, Simmons A, Eds. (Churchill Livingstone, Newyork) 1996:501-19.  Back to cited text no. 9    
10.Chakraborti CK, Chatterjee BD, Kundu D, Banerjee KL. Role of anaerobes in advanced adult periodontitis. In: Proceedings of the first Asian congress on anaerobic bacteria in health and disease. Mehta A, Kochar N, eds. 1987:202-4.  Back to cited text no. 10    
11.Beena VK, Francis J, Bhat M, Kotion M, Shivananda PG. Anaerobic bacteria in periodontal infections. J Indian Dent Assoc 1992;63:215-9.  Back to cited text no. 11    
12.Antony B, Kurian R, Faizal M, Verma BRR, Shivananda PG. Actinobacillus actinomycetemcomitans and anaerobes in periodontitis. Ind J Med Microbiol 1997;15:73-6.  Back to cited text no. 12    
13.Saglie FR, Smith CT, Newmann MG, Carranza FA Jr., Pertuised JH, Cheng L, et al. The presence of bacteria in the oral epithelium in periodontal disease: Immunohistochemical identification of bacteria. J Periodontal 1986;57:492-500.  Back to cited text no. 13    
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2004 - Indian Journal of Medical Microbiology
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