Detection of multidrug-resistant Salmonella enterica subsp. enterica serovar Typhi isolated from Iraqi subjects.

BACKGROUND AND AIM: Enteric fever initiated by Salmonella enterica subsp. enterica serovar Typhi (S. Typhi) is among the most consistent disease worldwide, particularly in developing countries. The present study aimed to isolate and identify S. Typhi from typhoid suspected patients and determine their antibacterial susceptibility testing. MATERIALS AND METHODS: Thirty blood samples were collected from typhoid suspected patients in Baghdad, Iraq. The samples were cultured on SS agar and XLD agar for screening of S. Typhi. The suspected colonies were picked up and subjected to Vitek 2 compact for biochemical identification and antibacterial susceptibility testing of the organisms. Molecular identification of the isolates was performed by real-time polymerase chain reaction (RT-PCR). RESULTS: Black colonies were observed on cultured plates. Out of 30 samples, 27 and 29 isolates were identified as S. Typhi using Vitek 2 compact and RT-PCR, respectively. The data of the present study revealed that the strains of S. Typhi were showing multidrug resistance. All S. Typhi strains exhibited resistance to penicillins (ticarcillin and piperacillin), cephalosporins 4th G (cefepime), and monobactam (aztreonam). However, all the strains showed susceptibility against carbapenems (imipenem and meropenem) and tetracycline (minocycline). CONCLUSION: RT-PCR and Vitek 2 compact showed a high level of accuracy in the detection of S. Typhi. Multidrug resistance was observed, which is an alert for the reduction of antibiotic consumption.

Detection and characterization of Streptococcus downei, a rare bacterial species of mutans streptococci from caries-active patients.

BACKGROUND: The oral bacteria, mutans streptococci (MS), are an etiological agent of dental caries. Of MS, Streptococcus downei are rarely isolated bacteria. AIM: The aim of this study was to isolate and characterize S. downei from caries-active subjects. MATERIALS AND METHODS: In all, 65 dental plaque samples were collected from dental caries-active subjects. All the isolates were further identified and characterized using 16S rDNA sequencing, biochemical tests, antibiogram, and minimum inhibitory concentration (MIC). RESULTS: Five isolates have been identified as S. downei using 16S rDNA sequencing. Phylogenetic analysis showed that S. downei was closely related to S. sobrinus. The biotype traits of these five isolates were IV (n = 3), V (n = 1), and variants (n = 2). The study proposed one new biotype, classified as biotype VIII for the variant strain. The antibiogram tests revealed that all the strains of S. downei were susceptible to all the antibiotics used in the study with higher sensitivity to penicillin and ampicillin. The MIC of ampicillin and erythromycin against S. downei was 0.047 and 0.39 µg/mL, respectively. CONCLUSION: The study reports the prevalence of S. downei in caries-active subjects and recommends further investigations to determine its role in the disease.

Determination of antibacterial activity and metabolite profile of Ruta graveolens against Streptococcus mutans and Streptococcus sobrinus.

BACKGROUND: Ruta graveolens is one of the most used phytomedicines. To date, there is no report of determining the bioactivity of R. graveolens against cariogenic causing bacteria (Streptococcus mutans and Streptococcus sobrinus). OBJECTIVE: The objective of the present study was to determine the antibacterial activity and metabolite profile of R. graveolens against S. mutans and S. sobrinus. MATERIALS AND METHODS: R. graveolens plant material was collected and processed in the month of February. The plant material was extracted by Soxhlet apparatus using methanol solvent. Two strains of S. mutans and two strains of S. sobrinus were isolated from dental caries-active participants and cultured on mitis salivarius-bacitracin agar. The antibacterial susceptibility testing of methanolic extract of R. graveolens was performed by disc diffusion method. The metabolite profile of the plant extract was determined using electrospray ionization-tandem mass spectrometry. RESULTS: The methanolic extract of R. graveolens showed a promising antibacterial activity against S. mutans and S. sobrinus. Two compounds named γ-fagarine and kokusaginine were identified from the methanolic extract of R. graveolens. CONCLUSION: The study concluded that R. graveolens contains significant antibacterial activity. However, further investigations are suggested to understand the anticaries properties of these pure compounds.

First Detection and Characterization of Streptococcus dentapri from Caries Active Subject.

INTRODUCTION: Mutans streptococci (MS) are a group of oral bacteria generally regarded as the principal agents in the pathogenesis of dental caries. AIM: The study aimed was characterize S. dentapri based on phylogenetic analysis and phenotypic methods from Caries Active Subject. MATERIALS AND METHODS: While sequencing MS species which were isolated from 65 caries active subjects, one strain of S. dentapri was detected. Dental plaque samples were processed and cultured on mitis salivarius bacitracin agar. S. dentapri was characterized using phylogenetic analysis, colony morphology characterization and biotyping. RESULTS: Among the study population, one strain designated as H14 was identified as S. dentapri by 16S rDNA sequencing. Morphologically, S. dentapri could not differentiate from other species of MS. S. dentapri H14 demonstrated biotype II biochemical characteristics of MS. The phylogenetic analysis showed S. dentapri is closely related to S. macacae. CONCLUSION: The study concludes that S. dentapri can inhabit the human oral cavity and therefore further investigations are warranted to determine its role in caries.

Isolation and Typing of Streptococcus mutans and Streptococcus sobrinus from Caries-active Subjects.

BACKGROUND: Streptococcus mutans and Streptococcus sobrinus are main etiological agents of dental caries. AIM: The aim of the study was to isolate, identify, characterize, and determine the minimum inhibitory concentration (MIC) of S. mutans and S. sobrinus from caries-active subjects. MATERIALS AND METHODS: Sixty-five plaque samples were collected from caries-active subjects aged between 35 and 44 years, processed and cultured on mitis salivarius bacitracin agar. All the bacterial isolates were subjected to morphotyping and the suspected colonies were identified by 16S rDNA sequencing. The S. mutans and S. sobrinus strains were characterized by biotyping and phylogenetic analysis. The MIC of ampicillin and erythromycin was determined by microtiter plate method. RESULTS: Of the study population, 41 isolates displayed typical colony morphologies of S. mutans and S. sobrinus. The 16S rDNA sequencing results revealed that 36 isolates were S. mutans and 5 isolates were S. sobrinus. The biotyping of these isolates demonstrated three biotypes, namely, biotype I (n = 35), biotype III (n = 1), and biotype IV (n = 2). However, 3 isolates exhibited variant biotypes. The phylogenetic analysis revealed that the clinical strains of S. mutans and S. sobrinus clustered independently along with respective reference strains. The average MIC of ampicillin and erythromycin against S. mutans and S. sobrinus was 0.047 µg/ml and 0.39 µg/ml, respectively. CONCLUSION: The 16S rDNA sequencing was an impeccable method for S. mutans and S. sobrinus identification when compared with morphotyping and biotyping methods. The study also suggested that nonspecific bacteria might be involved in caries formation.