Staphylococcus aureus ampicillin-resistant from the odontological clinic environment

Degree of Contamination of Gutta-Percha Points by Staphylococcus aureus (MRSA/MSSA) Strains

Methicillin-resistant Staphylococcus aureus (MRSA) is considered one of the most harmful bacteria to human health. Dentistry, like all healthcare disciplines, places great emphasis on preventing scenarios that may result in cross-infection. Although various tested and already used materials are suitable for filling the root canal system, Gutta-Percha (GP) remains the preferred and widely accepted gold standard.

OBJECTIVE

We performed an in vitro analysis of the contamination of GP points, regarding the strains of Methicillin-resistant (MRSA) and Methicillin-sensitive (MSSA) Staphylococcus aureus, using classical microbiology methods and molecular biology techniques.

METHODS

Gutta-Percha points of two different brands from opened packages (already in use for 1 month) were collected for analysis. The assessment involved incubating the GP points in Brain Heart Infusion (BHI) medium to detect microbial growth. Growing microorganisms were plated on a selective and differential chromogenic medium for MRSA/MSSA strains, and the identification of isolates was confirmed by Polymerase Chain Reaction (PCR). In the case of microbial growth, the GP point was submitted to a disinfection protocol.

RESULTS

From the 315 collected GP points, only 6 (1.9%) resulted in being positive for microbial growth. After confirmation by PCR, only one sample of the six GP points was contaminated by MRSA, and the remaining five were MSSA-contaminated. The disinfection protocol was effective in all contaminated GP points.

CONCLUSIONS

The Gutta-Percha points from opened pre-sterilized packages showed a very low degree of contamination by MRSA/MSSA. However, the detection of MSSA and MRSA strains raises concerns about potential contamination in dental clinic environments, and this risk cannot be considered negligible.

Nasal conveyance of Methicillin-resistant Staphylococcus aureus (MRSA) strains among dental professionals with varying levels of clinical exposure: A comparative study

OBJECTIVE

Any control program for MRSA requires identifying the whole hospital reservoir. The likelihood of conveyance of MRSA may be higher in dental settings. Hence, the aim was to compare the nasal conveyance MRSA among dental professionals with varying levels of clinical exposure in a tertiary dental hospital in South India.

METHODS

A total of 81 volunteers were stratified based on the number of years of clinical exposure. The nasal swabs were subjected to catalase and coagulase tests as well as antibiotic susceptibility test. Chi- Square test was done to compare the different types of organisms isolated from dental professionals with varied levels of clinical exposure.

RESULTS

Out of the total 81 isolates, 62.96% of the isolates were MSCONS (Methicillin sensitive coagulase negative staphylococcus), 20.98% of them were MRCONS (Methicillin resistant coagulase negative staphylococcus), 9.87% were MSSA (Methicillin sensitive staphylococcus aureus) and 3.7% were MRSA positive and 2.46% were other gram negative organisms.

CONCLUSIONS

MRCONS, MSSA and MRSA were shown to increase with an increase in the clinical exposure years.

Detection of Staphylococcus aureus (MRSA/MSSA) in surfaces of dental medicine equipment

Methicillin-Resistant Staphylococcus aureus (MRSA) represents one of the major causes of nosocomial infections, leading to high mortality. Surfaces in clinics, as well as the attending uniform and the hands of the dental doctor can be MRSA reservoirs. Having this in mind, the purpose of this study was to evaluate the presence of Methicillin-Sensitive Staphylococcus aureus (MSSA) and MRSA on dental medicine equipment surfaces. 354 Samples were collected from six equipment surfaces in six attendance areas before and after patient consultation and cultured in a selective medium. Polymerase Chain Reaction (PCR) was used to confirm the identity of bacterial strains as MRSA or MSSA. Data analysis was performed with chi-square tests with Bonferroni correction. It was observed 55.6% of uncontaminated samples. Contamination was: 17.5% MRSA (5.9% of samples collected before patient attendance and 11.6% after); 39.3% MSSA (14.1% collected before and 25.2% after). The prevalence of MRSA and MSSA was significantly higher after patient care. Integrated Clinic represented the most contaminated attendance area (MRSA − 41.7%, MSSA − 51.2%), the chair arm rest was the most contaminated surface for MRSA (29.7%) and the dental spittoon the most contaminated surface for MSSA (23.5%). Although a low level of contamination was observed, dental clinics, through patients possibly carrying bacteria, may be reservoirs for MRSA and MSSA transmission, and might contribute to potential nosocomial infections.

Isoenzymatic genotyping of Staphylococcus aureus from dairy cattle and human clinical environments reveal evolutionary divergences

Background

The genetic variability of 610 S. aureus isolates from the hands of professional dentists (A), dental clinic environment air (B), bovine milk from cows with and without mastitis (C), an insufflator for milking equipment (D) and milking environment air (E) was studied by isoenzyme genotyping and genetic and cluster analysis.

Results

Monoclonal and polyclonal patterns of S. aureus were detected in every bacterial population; however, isolates belonging to the same strain were not found among the populations, suggesting the genetic heterogeneity and the intrapopulation spread of strains. Genetic relationship analysis revealed the co-existence of highly related strains at low frequency among populations.

Conclusion

The data suggest that some strains can adapt and colonize new epidemiologically unrelated habitats. Consequently, the occurrence of an epidemiological genotypic identity can assume a dynamic character (spread to new habitats), however infrequently. A tendency of microevolutionary and genetic divergences among populations of S. aureus from human sources (AB) and bovine milk (DE), and especially the mammary quarter (C), is also suggested. This research can contribute to the knowledge on the distribution and dissemination of strains and the implementation of control measures and eradication of S. aureus in important dental clinic environments, as well as animal environments and dairy production.

Dynamics of the seasonal airborne propagation of Staphylococcus aureus in academic dental clinics

Objective

Staphylococcus aureus strains can be disseminated during dental treatments and occasionally lead to the contamination and infection of patients and dentists, which is an important public health problem. The dynamics of the airborne propagation and the genetic diversity of S. aureus isolated in an academic dental clinic environment were investigated using isoenzyme typing.

Material and Methods

The isoenzymes of 44 previously reported isolates were obtained from fresh cultures and extracted using glass beads. Nine isoenzymes were investigated using multilocus enzyme electrophoresis (MLEE). The genetic diversity and relationship among the strains (electrophoretic type – ET) were determined using statistics previously described by Nei²⁵ (1972) and the SAHN grouping method (UPGMA algorithm).

Results

Clonal pattern analyses indicated a high level of genetic polymorphism occurring among the 33 ETs, which were grouped into five taxa. Each taxon presented one or more clusters that were moderately related and that contained two or more identical/highly related isolates, revealing seasonal airborne propagation in these dental clinic environments.

Conclusions

These data suggest the occurrence of active microevolutionary processes in S. aureus as well as the possibility of environmental propagation during a 14-month time span. Such findings are important to show that multiuser academic dental clinics can retain certain strains that are spreadable to different niches.

Capacidade para o trabalho de cirurgiões-dentistas da atenção básica: prevalência e fatores associados

Resumo Objetivo: avaliar os fatores associados à capacidade para o trabalho de cirurgiões-dentistas. Métodos: a amostra foi constituída por 167 cirurgiões-dentistas vinculados à Estratégia Saúde da Família. Foram aplicados questionários sobre a capacidade para o trabalho, dados sociodemográficos, caraterísticas relacionadas ao trabalho, aspectos de saúde autorreferidos, estilo de vida e fadiga. Na análise univariada utilizou-se a estatística descritiva; na bivariada, o teste Qui-quadrado de Pearson, e, na multivariada, a regressão de Poisson. Resultados: 46,7% da amostra mostrou capacidade inadequada para o trabalho, sendo as variáveis independentes associadas: sexo feminino (RP=1,12; IC95%: 1,01-1,23), limpeza não adequada (RP=1,14; IC95%: 1,01-1,29), ambiente úmido (RP=1,35; IC95%: 1,15-1,59), ambiente de trabalho com muito barulho (RP=1,10; IC95%: 1,01-1,30), tarefas repetitivas e monótonas (RP=1,36; IC95%: 1,20-1,55), insatisfação com sono (RP=1,15; IC95%: 1,05-1,25), estado de saúde regular (RP=1,25; IC95%: 1,10-1,41), apresentar de uma a quatro morbidades diagnosticadas (RP=1,14; IC95%: 1,04-1,26), cinco ou mais morbidades (RP=1,52; IC95%: 1,38-1,70) e níveis altos de percepção de fadiga (RP=1,15; IC95%: 1,04-1,26). Conclusão: A amostra estudada apresentou incapacidade para o trabalho, que foi associada a fatores sociodemográficos, características do trabalho, aspectos de saúde e altos níveis de fadiga.

Risk of Methicillin-Resistant Staphylococcus aureus Transmission in the Dental Healthcare Setting: A Narrative Review

Objective.

Information on the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection transmission in dental healthcare settings was incomplete only few years ago; therefore, MRSA infection control guidelines were necessarily based on data extrapolated from other fields. Recently, publication of specific studies have made it possible to review such risk.

Methods.

Studies of MRSA infection in dentistry were searched for using EMBASE, MEDLINE, and Google and were allocated into the following sections: (1) direct evidence: documented cases of MRSA transmission in dentistry; (2) indirect evidence: carriage rates among dental healthcare providers (DHCPs) and patients (high carriage rates suggest that transmission is likely); (3) speculative evidence: MRSA occurrence in the dental environment (high environmental contamination probably increases the risk of infection); and (4) speculative evidence: MRSA carriage in human dental plaque and saliva (oral carriers may spread MRSA in the environment during dental therapy, with consequent environmental contamination and probable increased risk of infection).

Results.

Our findings were as follows. First, transmission has been ascertained during surgical interventions, particularly in surgical units and among head and neck cancer patients. Second, carriage rates among DHCPs were lower than those among other healthcare workers. Carriage rates among adult patients were low, whereas among pedodontic and special care patients rates were higher than those in the general population. Third, MRSA has been detected in the environment of emergency and surgical units and in dental hospitals. Some individuals in poor general condition were oral MRSA carriers.

Conclusions.

The occupational risk of MRSA infection among DHCPs is minimal. Among special patients (eg, special care, hospitalized and cancer patients) the risk of infection is high, whereas among the remaining patients undergoing conventional therapy such risk is probably low.

Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole) and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections.

Purification and structural characterization of a novel antibacterial peptide from Bellamya bengalensis: activity against ampicillin and chloramphenicol resistant Staphylococcus epidermidis

Increasing tendency of clinical bacterial strains resistant to conventional antibiotics has being a great challenge to the public's health. Antimicrobial peptides, a new class of antibiotics is known to have the activity against a wide range of bacteria resistant to conventional antibiotics. An antimicrobial peptide of 1676 Da was purified from Bellamya bengalensis, a fresh water snail, using ultrafiltration and reversed phase liquid chromatography. The effect of this peptide on Staphylococcus epidermidis resistant to ampicillin and chloramphenicol was investigated; the MIC and MBC values were 8 μg/ml and 16 μg/ml, respectively. Complete sequence of the peptide was determined by tandem mass spectrometry (MS/MS). Further, peptide net charge, hydrophobicity and molecular modeling were evaluated in silico for better understanding the probable mechanisms of action. The peptide showed the specificity to bacterial membranes. Hence, this reported peptide revealed a promising candidate to contribute in the development of therapeutic agent for Staphylococcal infections.