Biomedical Waste Management And Dental Microbiology Question And Answers

Biomedical Waste Management

 

Question 1. Write a brief on the disposal of biomedical waste.
Answer:

All the biomedical waste should be segregated and is disposed of as follows:

• Yellow bag container has anatomical waste. It should be directly sent to the disposal. Disposal of this type of biomedical waste is done by deep burial or incineration.
• Red bag container has infectious waste which is disposed of by deep burial or incineration. If highly infectious material is present, first the material is sterilized by autoclaving and then disposed of by landfilling.
• The blue bag consists of plastic and rubber disposables that need treatment before disposal. First of all these items are shredded, and then they are disinfected by putting them in a 1% bleaching solution for 30 minutes or in sodium hypochlorite, and then they are autoclaved. Now they are disposed of by landfilling or burial.
• Sharps should be kept in a puncture-proof container and need special treatment before disposal, i.e. either they are destroyed or disinfected by 1% sodium hypochlorite solution, and now they are disposed of in a sharp pit which should be well covered and protected and should not be accessible to rag pickers for its reuse.
• Non-infectious biomedical waste is disposed of by landfilling.

Read And Learn More: Microbiology Question And Answers

The description of disposal methods of biomedical waste is as follows: Disposal of biomedical waste is done by the following methods:

1. Landfilling
2. Deep burial
3. Sewage.

1. Landfilling:
   • This is a small burial pit of 2 meters in depth.
   • It should be half-filed with waste and then covered with lime within 50 cm of the surface before filling the rest of the pit with soil.
   • It is specially designed for the disposal of hospital waste.
   • For health and safety, a landfill site should be constructed away from residences, forests, and coastal waters.
   • If facilities are not available to treat the waste before disposal, landfills are regarded as an acceptable route of disposal.
   • Wastes falling under Category 5, i.e. discarded medicines, cytotoxic drugs, and Category 10, i.e. chemical wastes can be disposed of in a secure landfill.
2. Deep Burial: 
   • A trench 1.5 m wide and 2 m deep is excavated and at the end of each day, the refuse is covered with 20 to 30 cm of earth.
   • As the level of the trench reaches 40 cm from ground level, the trench should be filled with earth, compacted, and a new trench is dug.
3.  Sewage:  Liquid waste is disposed of in sewage drains

 

Dental Microbiology

 

Question 2. Enumerate microbial agents causing acute necrotizing ulcerative gingivitis with its lab diagnosis.
Answer:

Acute Necrotising Ulcerative Gingivitis (ANUG) is an acute inflammation of the gingiva along with irregularly shaped ulcers.

Enumeration of Microbial Agents causing ANUG

• Treponema species
• Prevotella intermedia
• Fusobacterium nucleatum (Fusiform bacilli)
• Borrelia vincentii (Spirochaete)
• Peptostreptococcus micros
• Porphyromonas gingivalis
• Selenomonas species
• Camphylobacter.

Lab Diagnosis of Microbial Agents

• Bacteriologic examination: Lab diagnosis is associated with the testing of fusiform bacilli and spirochaete, i.e. Borrelia vincentii.
• Fusiform bacillus associated with necrotizing ulcerative gingivitis is an elongated rod with tapered ends measuring 5 to 14 microns in length and 0.5 to 1µ in diameter.
• This non-motile microorganism is weakly gram-positive and occurs singly or in clusters.
• Borrelia vincenti is a gram-negative spirochaete with three to six long spirals.
• It measures 10 to 15 µ in length. It is actively motile
• Spirochetes and fusiform bacilli are demonstrated in stained smears of exudates from the lesion on microscopic examination.
• The spirochete T. palladium is visible on dark ground microscopy.
• A direct fluorescent antibody test is done for the detection of spirochete T. palladium
• Enzyme immunoassays are also done to detect spirochetes present in ANUG.
• Antibody tests, i.e. detection of specific IgM antibodies helpful in the detection of Treponema

Question 3. Write a short note on dental caries.
Answer:

In the pathogenesis of dental caries, an important role is played by cariogenic bacteria, i.e. oral streptococci, especially of group mutants and lactic acid bacteria (Lactobacillus spp.).

• It is believed that bacteria of the species Streptococcus mutans are the main factor that initiates caries and a very important factor in enamel decay.
• Bacteria of the genus Lactobacillus are important in further caries development, especially in the dentin.
• Mutans streptococci and lactobacilli are characterized by the ability to grow in an acid environment and the property of rapid metabolism of sugars supplied in the diet to organic acids including lactic acid.
• The microbial community from dentinal lesions is diverse and contains many facultative and obligate anaerobic bacteria belonging to the genera Actinomyces, Bifidobacterium, Eubacterium, Lactobacillus, Parvimonas, and Rothia.
• Streptococci are recovered less frequently. Caries can also be caused by other bacteria including members of the mitis, anginosus, and salivarius groups of streptococci, Propionibacterium, Enterococcus faecalis, and Scardovia.

Mutans Streptococci:

• Mutans streptococci are the most cariogenic pathogens as they are highly acidogenic, producing short-chain acids that dissolve the hard tissues of teeth. They metabolize sucrose to synthesize insoluble extracellular polysaccharides which enhance their adherence to the tooth surface and encourage biofilm formation.
• The reactions are catalyzed by three isozymes of glucosyltransferases. The most important mutans streptococci isolated from tooth caries samples are S. mutans and S. sobrinus. S. mutans is more cariogenic than S. sobrinus because of specific cell-surface proteins, which aid in its primary attachment to the tooth. S. sobrinus lacks such proteins.

Streptococcus Mutans:

• S. mutans is able to metabolize a number of sugars and glycosides such as glucose, fructose, sucrose, lactose, galactose, mannose, etc. In the presence of extracellular glucose and sucrose, S. mutans synthesizes intracellular glycogen-like polysaccharides (IPSs).
• S. mutans also produce mutacins (bacteriocins), which are considered to be an important factor in the colonization and establishment of S. mutants in the dental biofilm.

Streptococcus Sobrinus: S. sobrinus has been implicated in caries development, particularly in instances where caries development appears to be independent of S. mutans. It is interesting that S. sobrinus displays higher acid production and acid tolerance compared to S. mutans.

Lactobacilli: Among the Lactobacillus rods in the oral cavity occur L. acidophilus, L. casei, L. fermentum, L. delbrueckii, L. plantarum, L. jensenii, L. brevis, L. salivarius, and L. gasseri. Lactobacilli are divided into two main groups:

• Omofermentative: Omofermentative which in the fermentation process of glucose produces mainly lactic acid, for example, Lactobacillus casei, Lactobacillus acidophilus,
• Heterofermentative:  Heterofermentative which in addition to lactic acid produces acetate, ethanol, and carbon dioxide, for example, Lactobacillus fermentum.

Lactobacilli are isolated from deep caries lesions but rarely just before the development of dental caries and early tooth decay. It is believed that they are pioneering microorganisms in the caries progress especially in dentin.

Veillonella: It is gram-negative cocci which is commonly found in plaque. It utilizes lactic acid by converting it to propionic acid and other weak acids