Isolation and Identification of Gram Positive and Gram Negative Bacteria Causing Dental Caries in Children in Thi Qar province


  • Nawal Fahaed Diash Department of Microbiology, Medical Microbiology, College of Medicine, University of Thi-Qar
  • Faten Naeem Abbas Department of Microbiology, Medical Microbiology, College of Medicine, University of Thi-Qar


Dental Caries, cariogenic bacteria


Background: Dental caries is an infectious disease-causing tooth demineralization and cavities. Dental caries in
children is caused by the combination of three major factors carbohydrates, the presence of caries bacteria on dental
plaque, and the rapid impact of hard tooth surfaces. The mouth contains a large number of bacteria, including a few
species that cause dental caries called cariogenic bacteria. Gram positive bacteria are the main contributors to caries in
the teeth
Methods: A study was conducted in Thi-Qar province between August and December 2023 AD, involving 100
swabs and dental plaque samples from (70 patients and 30 controls) aged 3-11 years. The samples were processed and
cultivated in a specific culture medium.
Conclusions: The current investigation demonstrated a high rate of Gram-positive bacteria isolated from dental
cavities in children aged 3 to 11 years. Gram stain, biochemical tests, and VITEK 2 compact results showed that grampositive bacteria accounted for 81% (180 isolates) and gram-negative bacteria for 19% (42 isolates). There were 109
isolates with typical Streptococcus colony morphologies


Zhang JS, Chu C-H, Yu OY. Oral microbiome and dental caries development. Dentistry journal. 2022;10(10):184.

Ahmed NM, Tariq P. antibiotic susceptibility profile of viridans group streptococci with respect to prevalence of

dental caries. 2023.

Pitts NB, Zero DT, Marsh PD, Ekstrand K, Weintraub JA, Ramos-Gomez F, et al. Dental caries. Nature reviews

Disease primers. 2017;3(1):1-16.

Jiang Q, Liu J, Chen L, Gan N, Yang D. The oral microbiome in the elderly with dental caries and health. Frontiers

in cellular and infection microbiology. 2019;8:442.

Simón-Soro A, Belda-Ferre P, Cabrera-Rubio R, Alcaraz L, Mira A. A tissue-dependent hypothesis of dental caries.

Caries research. 2013;47(6):591-600.

Bustamante M, Oomah BD, Mosi-Roa Y, Rubilar M, Burgos-Díaz C. Probiotics as an adjunct therapy for the

treatment of halitosis, dental caries and periodontitis. Probiotics and antimicrobial proteins. 2020;12:325-34.

Veale M, Ajwani S, Johnson M, Nash L, Patterson T, George A. The early childhood oral health program: a

qualitative study of the perceptions of child and family health nurses in South Western Sydney, Australia. BMC Oral

Health. 2016;16(1):1-10.

Zhang Q, Ma Q, Wang Y, Wu H, Zou J. Molecular mechanisms of inhibiting glucosyltransferases for biofilm

formation in Streptococcus mutans. International Journal of Oral Science. 2021;13(1):30.

Shao C, Jin B, Mu Z, Lu H, Zhao Y, Wu Z, et al. Repair of tooth enamel by a biomimetic mineralization frontier

ensuring epitaxial growth. Science advances. 2019;5(8):eaaw9569.

Burcham ZM, Garneau NL, Comstock SS, Tucker RM, Knight R, Metcalf JL. Patterns of oral microbiota

diversity in adults and children: a crowdsourced population study. Scientific reports. 2020;10(1):2133.

Kim K, Choi S, Chang J, Kim SM, Kim SJ, Kim RJ-Y, et al. Severity of dental caries and risk of coronary

heart disease in middle-aged men and women: A population-based cohort study of Korean adults, 2002–2013.

Scientific reports. 2019;9(1):10491.

Goh CE, Trinh P, Colombo PC, Genkinger JM, Mathema B, Uhlemann AC, et al. Association between

nitrate‐reducing oral bacteria and cardiometabolic outcomes: results from ORIGINS. Journal of the American Heart

Association. 2019;8(23):e013324.

Misaki T, Fukunaga A, Shimizu Y, Ishikawa A, Nakano K. Possible link between dental diseases and

arteriosclerosis in patients on hemodialysis. PloS one. 2019;14(12):e0225038.

Süzük S, Kaşkatepe B, Çetin M. Antimicrobial susceptibility against penicillin, ampicillin and vancomycin

of viridans group Streptococcus in oral microbiota of patients at risk of infective endocarditis. Infez Med.


Fritsche T, Swoboda S, Olson B, Moore F, Meece J, Novicki T. Evaluation of the Sensititre ARIS 2X and

Vitek 2 automated systems for identification of bacterial pathogens recovered from veterinary specimens. LACROSSE

Univ Wisconsin. 2011.

Ali AF. The Effect of Zinc Oxide Nanoparticles on Streptococcus mutans of Human Saliva (In Vitro Study).

Edwardsson S. The caries-inducing property of variants of Streptococcus mutans. Odontologisk revy.


Luis M. Color atlas of medical bacteriology: Zondervan; 2004.

Procop GW, Church DL, Hall GS, Janda WM. Koneman's color atlas and textbook of diagnostic

microbiology: Jones & Bartlett Learning; 2020.

F. MJ. Biochemical test for identification of medical

bacteria. the Williams Wilkins-BaltimorUSA. 2000.

Leboffe M, Pierce B. A photographic atlas for the microbiology laboratory 3rd Edition. Morton Publishing

Company; 2005.

Jubair HH. The relationship between biofilm forming and antibiotics resistance of streptococcus mutans

isolated from dental caries. Int J Curr Microbiol App Sci. 2015;4(5):568-74.

Radhi LY, AL-Ataby FH. Identification of Viridans Group Streptococci's virulence factor proteins and

resistance rate in dental caries patients in Al-Nasiriyah City, Iraq. The Peerian Journal. 2024;26:56-71.

Al-Mendalawi MD, Karam NT. Risk factors associated with deciduous tooth decay in Iraqi preschool

children. Avicenna journal of medicine. 2014;4(01):5-8.

Wafa Abdul Wahed Jahil Al Kaabi AHAH, Majid Kazem Abboud Al Shibli. Phenotypic and molecular

characterization of Streptococcus mutans bacteria isolated from the mouth and testing their ability to form biofilms

and their resistance to antibiotics. Pure Sciences of Qadisiyah 2016; 21, 2.

Simon L. The role of Streptococcus mutans and oral ecology in the formation of dental caries. 2007.

Abd Al-Zahra HS, Saleh MB. Isolation and identification of Streptococcus mutans from dental caries patients

at Thi-Qar province/Iraq. JOURNAL OF THI-QAR SCIENCE. 2018;6(4).

Jindal L, Dua P, Mangla R, Gupta K, Vyas D, Gupta P. Dental Caries in Relation to Socioeconomic Factors of

and 12-year-old Schoolchildren of Paonta Sahib, Himachal Pradesh, India: An Epidemiological Study. International

Journal of Clinical Pediatric Dentistry. 2020;13(4):395.

Elamin A, Garemo M, Mulder A. Determinants of dental caries in children in the Middle East and North

Africa region: a systematic review based on literature published from 2000 to 2019. BMC Oral Health.


Ali AM. Isolating and diagnosing some bacteria and yeasts associated with some oral diseases in the city of

Nasiriyah and testing their drug sensitivity. Faculty of Education: Dhi Qar University. Iraq.; 2006.

Landman D. Management of infections due to resistance Staphylococcus aureus. Am Infect. 2001;30:225-40.

Fong IW. Infections and their role in atherosclerotic vascular disease. The Journal of the American Dental

Association. 2002;133:7S-13S.

Hadi UM. A microbiological study of the causes of tooth decay, gingivitis, periodontitis, and periradicular

abscesses in Najaf Governorate. University of Kufa. Iraq.: University of Kufa. Iraq.; 2002.

Tanner T, Päkkilä J, Karjalainen K, Kämppi A, Järvelin MR, Patinen P, et al. Smoking, alcohol use,

socioeconomic background and oral health among young Finnish adults. Community dentistry and oral epidemiology.


Kokaz Of. Study The effect of Probiotic Prepared from Lactobacillus acidophilus on Adhesion of The

bacteria Isolated from Dental Caries. journal of kerbala university. 2011;9(2).

Al-Aswad F. Prevalence and microbiology of oral mucosal lesions in a sample of complete denture wearers:

A thesis submitted to College of Dentistry, Univrrsity of Baghdad, Iraq. MSc …; 1999.

Sulaiman A. Quantitative measurement of urea content in saliva, acquired pellicle and dental plaque in

relation to dental caries susceptibility in human adults. A master thesis, College of Dentistry, university of Baghdad.