Join Our Whatsapp and Telegram Channel to Get Free eBooks Telegram | Whatsapp

Staphylococcus aureus

Domain: Bacteria
Species:S. aureus

Table of Contents

Overview of Staphylococcus aureus

Staphylococcus aureus can be described as a gram-positive round-shaped bacterium that is one of the Firmicutes and is a typical member of the microbiota in the body. It is often located in the respiratory tract as well as within the pores of the skin. It’s often positive for catalase as well as nitrate reduction and is a facultative anaerobe which can develop without the requirement for oxygen. However, S. aureus is usually seen as a commensal to the human microbiota , it can also be an opportunistic pathogen. It is frequently the source of infections on the skin, including abscesses and respiratory infections, such as sinusitis, as well as food poisoning.

The pathogenic strains typically cause infections through the production of virulence factors, such as powerful protein toxins, as well as the production of a cell-surface protein that binds to antibodies and inhibits their activation. S. aureus is one of the leading pathogens for deaths associated with Antimicrobial resistance and the emergence of antibiotic-resistant strains such as methicillin-resistant S. aureus (MRSA) is a worldwide problem in clinical medicine. In spite of a great deal of studies and developments, there is no vaccine against S. aureus is recognized as safe.

The estimated 20-30% to 30 percent of the population have been identified as long-term carriers for S. aureus that is found in the normal skin flora in the nostrils and as a normal resident inside the lower reproductive tracts of females. S. aureus is a cause of various ailments, ranging from minor skin irritations, such as impetigo, pimples boils, cellulitis, carbuncles, scalded-skin syndrome and abscesses to life-threatening illnesses like osteomyelitis, meningitis and pneumonia as well as endocarditis, asthma, toxic shock syndrome and sepsis.

It’s still among the top five causes of hospital-acquired infections . It is frequently the reason for wound infections after surgical procedures. Each year, approximately 500,000 patients at hospitals in the United States contract a staphylococcal infection, primarily caused due to S. aureus. As many as 50,000 deaths per annually in United States are linked with S. aureus-related infections.

Discovery of Staphylococcus aureus

It was in 1880 that Alexander Ogston, a Scottish surgeon, was able to discover that Staphylococcus causes wound infections after noticing clusters of bacteria present in the the pus of an abscess surgically created during the procedure he was carrying out. He identified it as Staphylococcus due to its clustered look visible under the microscope.

In 1884, German researcher Friedrich Julius Rosenbach identified Staphylococcus aureus, separating this from Staphylococcus albus, a closely related bacterium. In the 1930s doctors started using an improved test that was streamlined to determine any signs of S. aureus-related infection through the use of coagulase tests that detects an enzyme created by the bacteria. Before 1940, S. aureus infections caused death in many patients. Doctors discovered, however, that penicillin was able to treat S. aureus infection. However, towards the time the 1940s ended penicillin resistance had become widespread in this bacteria population, and outbreaks of resistant strains began to develop.

Characteristics of Staphylococcus aureus

  • Staphylococcus aureus is a Gram-positive bacterium (stain purple by the Gram stain) which are cocci-shaped and are usually arranged in groups that are classified as “grape-like.”
  • On media, these microorganisms may grow up to 10% salt. The colonies can be yellow or golden (aureus refers to yellow or golden).
  • They can develop either aerobically or anaerobically (facultative) and at temperatures ranging from 18 C and 40 C.
  • Common biochemical identification tests are catalase-positive (all disease-causing Staphylococcus species) as well as coagulase positiv (to make it easier to distinguish Staphylococcus aureus in comparison to different Staphylococcus species) and novobiocin-sensitive (to identify Staphylococcus saprophyticus) and mannitol-fermentation positive (to differentiate from Staphylococcus epidermidis).
  • MRSA strains possess mec genes in the bacterial genome, which is a part of the Staphylococcal mec (SCCmec) region, which confers resistance to multiple antibiotics based upon the SCCmec type.
  • MEC encodes for the protein called PBP-2a (penicillin-binding protein 2a). PBP-2a is a protein that binds penicillin (PBP) or an the essential enzyme of the bacterial cell wall which catalyzes the creation of peptidoglycans within the cell wall of the bacterial organism.
  • PBP-2A is less able for binding to beta-lactamas (and others penicillin-derived antibiotics) in comparison to other PBPs and, therefore, PBP-2A remains catalyzing the creation of the cell wall of the bacterial even when it is in the presence of numerous antibiotics. This is why S. aureus strains which synthesize PBP-2A are able to develop in the presence numerous antibiotics. These MRSA strains are resistant to several antibiotics. MRSA strains are immune to methicillin Nafcillin, the cephalosporins and oxacillin.

Epidemiology of Staphylococcus aureus

Staphylococcus aureus (including resistant strains to drugs like MRSA) can be found on the mucous and skin membranes. Humans are the main reservoir for these bacteria. It is believed that as high as 50% of the population is colonized, and that around 15% of people continue to carry S. aureus in their anterior nares. Certain populations are more likely to have more frequent percentages in S. aureus colonization (up to 88%) for example, health care professionals, those who inject frequently with needles (i.e. diabetics, diabetics, people who are intravenous (IV) user) and hospitalized patients and those with immunodeficiency. S. aureus is transferred from person-to-person via the direct contact or by fomites

Morphology Of Staphylococcus Aureus

Staphylococcus Aureus, a prominent bacterium in the realm of microbiology, exhibits distinct morphological features that have been extensively studied and documented in scientific literature. This bacterium, commonly referred to as S. Aureus, possesses several characteristics that distinguish it from other microorganisms.

  1. Cellular Shape: S. Aureus is characterized by its spherical cellular structure, technically termed as cocci. This round shape is a defining trait of the bacterium.
  2. Size: The diameter of an individual S. Aureus cell is approximately 1 micron. This minute size is consistent across the majority of samples observed under microscopic examination.
  3. Cellular Arrangement: Under microscopic observation, S. Aureus often presents itself in a unique arrangement reminiscent of grape clusters. This grape-like clustering is a hallmark of its morphology.
  4. Motility: One of the notable features of S. Aureus is its non-motile nature. The bacterium lacks the capability to move independently.
  5. Flagellation: In line with its non-motile characteristic, S. Aureus is non-flagellated. It does not possess flagella, the whip-like structures that some bacteria use for movement.
  6. Sporulation: S. Aureus is non-sporing, meaning it does not produce spores. Spores are typically dormant and resistant cells that some bacteria form to survive unfavorable conditions.
  7. Capsular Presence: While not universal across all strains, certain strains of S. Aureus have been identified to possess a capsule. This outer protective layer can play a role in the bacterium’s virulence and interaction with its environment.
  8. Gram Staining: A crucial aspect of bacterial classification, the Gram stain, reveals that S. Aureus is Gram-positive. This indicates the presence of a thick peptidoglycan layer in its cell wall, which retains the crystal violet stain during the Gram staining procedure.

In conclusion, Staphylococcus Aureus, with its distinct morphological features, stands as a unique entity in the vast domain of microbiology. Its characteristics, as detailed above, not only aid in its identification but also provide insights into its biology and interactions with its surroundings. As with all scientific observations, it is imperative to approach the study of S. Aureus with objectivity, precision, and a commitment to furthering our understanding of this significant bacterium.

Habitat of Staphylococcus aureus

Their habitat is comprised of both animals and humans. They form part of the skin’s natural fauna, particularly colonizing the mucous membranes of the external. But, they are typically present in the environment (untreated soil, water and other contaminated items).

Methods of infection include damaged mucosa or skin, as well as the ingestion of food items contaminated with infection. Staphylococcus aureus can live in dry conditions for a period of time, ranging from hours to months, dependent on the strain.

Biochemical characteristics of Staphylococcus aureus

Methyl redPositive
Gelatin hydrolysisNegative

Fermentable sugar

Fermentable sugarObservation
GlucoseAcid production
GalactoseAcid production
LactoseAcid production
MaltoseAcid production
SucroseAcid production
StarchNo acid production

Cultural Characteristics of Staphylococcus Aureus

  1. NAM (Nutrient Agar Medium): 
    1. Circular shape, 
    2. 2-4 mm in Size, 
    3. Smooth Surface, 
    4. Golden yellow color, 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  2. MacConkey agar medium:
    1. Circular shape, 
    2. 2-4 mm in Size, 
    3. Smooth Surface, 
    4. Pink, 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  3. Blood Agar Medium:
    1. Circular shape, 
    2. 1-4 mm in Size, 
    3. Smooth Surface, 
    4. Light golden yellow, surrounded by clear zone (beta hemolysis). 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  4. Mannitol Salt Agar:
    1. Circular shape, 
    2. 2-4 mm in Size, 
    3. Smooth Surface, 
    4. Yellow, 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  5. Milk Agar:
    1. Circular shape, 
    2. 3-5 mm in Size, 
    3. Smooth Surface, 
    4. Golden yellow (Pigment production enhanced). 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  6. Brain heart infusion agar: 
    1. Circular shape, 
    2. 3-5 mm in Size, 
    3. Smooth Surface, 
    4. Yellow pigmented colonies. 
    5. Opaque Structure, 
    6. Easily emulsifiable.
  7. Tryptic Soy Agar: circular, convex, and entire margin. 
  8. Tellurite-polymyxin-egg yolk: Egg yolk reaction, Black colonies.
  9. Phosphatase medium: Phosphatase production.
  10. DNAse medium: Deoxyribonuclease production.
  11. Polymyxin-coagulase-Mannitol: Coagulase reaction, Mannitol fermentation.
  12. Columbia CNA (Staph/Strep selective medium): Pigment Haemolysis.
  13. Egg yolk-azide: Egg yolk reaction.
  14. KRANEP: Mannitol fermentation, Egg yolk reaction, Pigment production
  15. Staph 4S: Egg yolk reaction, Grey/dark-grey colonies.
  16. Staph 110: Mannitol fermentation, Gelatin liquefaction, Pigment production, Egg yolk reaction.
  17. Improved Vogel and Johnson (PCVJ): Black colonies, Mannitol fermentation, DNAse production.
  18. Vogel and Johnson: Black colonies, Mannitol fermentation.
  19. Rabbit plasma-fibrinogen (RPF): Coagulase reaction, White or grey or black colonies.

Virulence factors of Staphylococcus aureus

1. Enzymes

S. aureus creates a variety of enzymes like cocoagulase (bound as well as free coagulases) that aid in its conversion from fibrinogen fibrin, which causes clots. This are important for skin infections.

  • Hyaluronidase (also called spreading factor) is a enzyme that breaks down hyaluronic acid and assists spread it.
  • Deoxyribonuclease that is a DNA degrader it helps protect S. aureus against the neutrophil trap-mediated killing.
  • S. aureus produces lipase that helps digest the lipids.
  • Staphylokinase is a fibrin-dissolving help spread.
  • Beta-lactamase for drug resistance.

2. Exotoxins

Three kinds of exotoxins are produced by various kinds of Staphylococcus:

  • Superantigens: Their exposure could cause a range of reactions ranging from the toxic shock syndrome, to gastroenteritis.
  • Exfoliative exotoxins: They produce proteases that trigger exfoliation of the skin. This condition is typically seen at a very early age in children.
  • Bicomponent toxins: Bicomponent toxins include PVL encoded by the bacteriophage in MRSA strains

3. Adherence Factors (Adhesins)

The binding to the host cell surface of S. aureus onto the surface of the host cell that initiates colonization is accomplished by adhesins of various types. A major category of S. aureus adhesins consists of proteins that are covalently linked onto the cell’s glycosycans (via the threonine atom in the signal motif of sorting on their C-terminus) and specifically adhere to cells’ plasma and extracellular matrix (ECM) components. They collectively are referred to as the microbial surface component that recognizes adhesive matrix molecules (MSCRAMMs). The molecules are able to recognize most significant constituents in the ECM or blood plasma which include fibrinogen, fibrinnectin and collagens.

The most common members of the MSCRAMM family are staphylococcal proteins A (SpA) as well as fibronectin-binding protein B and A (FnbpA as well as FnbpB) collagen-binding proteins, and the clumping factors (Clf) Proteins A and B.

4. SpA

SpA is an excellent illustration of one of the well-known and well-studied S. aureus virulence factors which have recently been able to demonstrate new properties, and play a major part in the development of pneumonia. Since the beginning, SpA is known to be a 42-kDa protein, which is attached to the cell wall of bacterial. It is part of the MSCRAMM family because it is able to bind to of Willebrand factor, a huge glycoprotein that plays a role in platelet adhesion in the presence of damage to the endothelial.

SpA contains five domains that repeat (E, D, A, B and C) with each has a high affinity binding with the Fc region of immunoglobulin (Ig) G and the Fab region of Ig of the subclass VH3. Its interaction with Fc of IgG inhibits phagocytosis because the bacteria that are coated by IgG in an unsuitable configuration are not recognized by the Fc receptor located on PMN. A further result of the capacity of SpA to connect to B lymphocytes with IgM with heavy chain VH3 is stimulation of proliferation, which results in the loss of a substantial portion of the B cell repertoire.

In addition to SpA inhibiting opsonization through adhering to Fc part of immunoglobulins SpA was speculated to exert a direct influence on the cells that make up the respiratory epithelial system even without IgG. In the event of infection of the airways in which serum components are absent, SpA plays a chief role in the onset of pneumonia via activating interleukin- (ILand) 8 expression, and the recruitment of PMN to the airways.

Role of SpA in TNFR1 regulation:

  • (a) SpA is recognized by the TNFR1 receptor and the signaling cascade starts by those adaptor proteins, TRADD/RIP/TRAF2, that later stimulate MAPK Kinases (p38 as well as JNK1/2) and trigger the translocation of transcription factors such as such as NF-kB and AP-1 to the nucleus. The activation of AP-1 and NFKB results in the transcription of genes that encode proinflammatory chemical mediators and chemokines.
  • (b) SpA by interplay through interaction with EGFR in addition to activation c-Src Erk1/2 triggers the TACE activity (ADAM-17) that cleaves and removes TNFR1 from the airway surface. It then becomes available for neutralization of the free SpA and TNF-a-ligands. AP-1 activater protein 1; ATF-2 activating transcription factor. EGFR epidermal growth receptor; NF-kB, nuclear factors kB; RIPis a receptor-interacting protein; and TACE, tumor necrosis factors-converting enzyme. TNFR1, tumor necrosis receptor 1. TRADD tumor necrosis factor receptor (TNFR+) with death domain TRAF2, tumor necrosis receptor-associated factor.
Role of SpA in TNFR1 regulation:
Role of SpA in TNFR1 regulation:

5. β-Toxin (β-Hemolysin)

In the group of S. aureus toxins there is little information about its role in the treatment of lung injuries and pneumonia. Based on the research findings, S. aureus b-toxin is a Mg2+-dependent neutral Sphingomyelinase which hydrolyzes sphingomyelin from the plasma membrane of the host cell to produce phosphocholine as well as an active secondary messenger the ceramide. Based on the chain length of the fatty acids they contain as well as the mechanism of metabolism they may trigger many effects in cells of eukaryotes, such as stimulation of the second messenger system as well as activation of MAPKs and changes to the shape of cells, and the process of apoptosis.

6. PVL

Panton-Valentine leukocidin is among numerous extracellular cytotoxins made in the body of S. aureus. Research suggests that the exotoxin PVL as a factor that causes virulence in necrotizing disorders.

Certain varieties from S. aureus may produce the toxin known as Panton-Valentine-Leukocidin (PVL) which makes people who are affected more vulnerable to developing illness. The toxin causes lung tissue destruction through activation and then killing polymorphonuclear Leukocytes (white blood cells). Expression of PVL could result in persistent inflammation, bone deformation and even spread to surrounding tissue as evidenced by the model for rabbit osteomyelitis. One of the most serious complications of PVL sepsis can be necrotizing hemorrhagic pneumonitis that is linked to a high mortality rate.

6. Superantigens

Superantigens, also known as antigens, can trigger the toxic shock syndrome (TSS). This category includes 25 , staphylococcal enterotoxins (SEs) that have been discovered to date and are named alphabetically (SEA SEZ) which includes enterotoxin type A as well as the toxin that causes toxic shock syndrome TSST-1, which triggers TSS caused by tampon use. TSS is characterised by a rash, fever and low blood pressure shock and multiple organ failure and peeling of the skin. The absence of antibodies to TSST-1 is a factor in the development of TSS. Different strains that are a part of S. aureus may create an enterotoxin which can be the cause of a form of gastroenteritis. The form of gastroenteritis that is described here is self-limiting, and is characterized by vomiting and diarrhea that lasts for 1-6 hours following the ingestion of the toxin. It is characterized by healing taking between 8 and 24 hours. The symptoms include nausea as well as vomiting, diarrhea and abdominal pain that is severe.

7. Exfoliative toxins

Exfoliative toxins are exotoxins involved in the condition staphylococcal-scalded skin syndrome (SSSS) which is a condition that manifests mostly in children and infants. It can also be seen in nurseries at hospitals. The protease action of exfoliants causes the itching of the face that is seen by SSSS.

8. Small RNA

The number of small RNAs that are involved in the regulation of bacterial virulence S. aureus are increasing. This could be due to factors like increased biofilm formation because of higher levels of small molecules. Examples include RNAIII is a component of SprD RsaE, SprA1, SSR42, ArtR, SprX and Teg49.

9. Protein A

Protein A is linked to staphylococcal pentaglycine bridges of peptidoglycan (chains consisting of five glycine residues) via the transpeptidase kindase A. Protein A is an IgG-binding protein. is a binder to the Fc region of an antibody.

10. Staphylococcal pigments

Certain varieties that are part of S. aureus can produce staphyloxanthin which is a golden-colored carotenoid pigment. This pigment is an antivirulence agent, mostly because it is an antioxidant in bacterial cells that aids the microbes to avoid the reactive oxygen species that the immune system of the host uses to eliminate pathogens.

Methods of Detection and Enumeration of S. aureus

A. Conventional Techniques

1. Enrichment

When S. aureus are present in low numbers, detection may require enrichment. Liquid media containing NaCl have been used but cannot be recommended because stressed cells are recovered poorly. Other liquid media are more suitable as selective enrichment medium for S. aureus, including Giolitti and Cantoni broth and Baird-Parker (BP) broth.

2. Selective Plating

When numbers are sufficiently high, S. aureus may be isolated from foods by direct plating on selective media. Simple selective media containing NaCl or polymyxin have long been available but cannot be recommended in preference to BP agar. BP agar is relatively efficient for recovering stressed cells. BP agar contains egg yolk plus tellurite for diagnostic purposes, pyruvate plus glycine as selective growth stimulators and tellurite plus lithium chloride as selective inhibitors. Although S. aureus colonies on BP agar plates are characteristically jet black surrounded by a white rim, an opaque zone and a zone of clearing, some strains of S. aureus are uncharacteristic in that they produce colonies that are lighter in color than normal, while other strains lack a zone of opaqueness or clearing. After incubation of BP agar plates, however, presumptive S. aureus colonies are selected for confirmatory testing.

3. Confirmatory Testing

Production of coagulase or TNase are the tests most commonly used to confirm the identity of presumptive S. aureus isolates, although it is now known that neither enzyme is unique to S. aureus. Commercially available slide agglutination test kits detecting clumping factor and protein A increasingly are being used for identification of S. aureus. None of the aforementioned tests are 100% reliable and, therefore, none can be relied on as the sole confirmatory test.

4. Identification by Mass Spectrometry

Mass spectrometry is becoming popular for bacterial identification in clinical microbiology laboratories. Enthusiastic reports relate the very good performance of this technology for species identification, including staphylococci. Studies showed correct identification in 93.2% of the 230 bacterial isolates using matrix-assisted laser desorption ionization timeof-flight mass spectrometry (MALDI-TOF-MS) highlighting the high performance of this technology for coagulase-negative staphylococci (CoNS) identification when compared with two other commercialized routine identification systems (BD Phoenix from Becton Dickinson and VITEK-2 from bioMérieux). 

Similarly, MALDI-TOF-MS Biotyper (Bruker Daltonics) was able to identify a collection of 156 strains representing 22 different species, including S. aureus and obtained concordant identification for 99.3% of the species previously identified using a sodA gene–based oligonucleotide array.

5. Enterotoxin Production

Detection of SEs is routinely carried out using immunological methods, although biological assays using kittens, rhesus monkeys, and chimpanzees have been described. Few laboratories have the facilities for handling these animals and such methods are used only for special purposes. Of the immunological methods available, gel diffusion especially double-gel diffusion with a reference toxin included ensuring the specificity of reactions have been the methods of choice for years. 

These methods, however, have been largely supplanted by reverse-phase latex agglutination (RPLA) and enzyme-linked immunosorbent assays (ELISAs), which are more sensitive and are commercially available as microtiter plate or polystyrene bead assay kits. Detection of SE production in pure cultures is easy to perform by using immunological methods (e.g., RPLA or ELISA). For detection of SE produced in foods using gel-diffusion methods, it is necessary to carry out extraction, purification, and concentration steps before assaying for toxin. Use of the much more sensitive RPLA and ELISA assays for SE detection in foods means that simple extraction procedures usually are sufficient. The original ELISAs used polyclonal antibodies to detect SE but subsequently, monoclonal antibodies have been used to increase the sensitivity of the assay.

B. Molecular Techniques

1. Isolation and Identification

DNA-based methods in conjunction with traditional cultural methods of enrichment are often employed to identify S. aureus within food items. The direct identification of S. aureus in food products by using DNA-based methods is the preferred method however there are a number of issues to be resolved before it can be implemented regularly. 

For instance, the using polymerase chain reaction (PCR)-based methods to detect of S. aureus and other pathogens is impeded due to interference with the PCR reaction because of inhibiting substances present in specific food items. The methods for making samples are continually improved and new assay formats are being developed that provide the possibility of faster and accurate specific detection and the identification of S. aureus in food, compared to the use of traditional methods. Genes that are involved for the creation of coagulase protein A and TNase in S. aureus are detectable by using PCR technology.

2. Typing

The traditional methods of the typing of S. aureus (serotyping, biotyping and bacteriophage typing) have been completely replaced in recent years with the development of methods such as multilocus enzyme electrophoresis restriction fragment-length polymorphisms; electrophoresis using pulsed field gels of macro-restricted DNA the use of PCR-sequencing techniques that rely on only one locus, for example, proteins A repetition typing (spatyping) or using multiple loci, for instance, the multilocus sequence typing (MLST) or multilocus variable tandem number repeats analysis.

The methods of molecular typing have been proven to be effective discriminators specific to the strain for the epidemiological characterisation of S. aureus. Furthermore due to their speed, convenience and power of discrimination they permit greater depth of study into the pathology of this organism within the food chain as well as in the clinical context.

3. Enterotoxins

The most common methods for molecular biology require PCR. These techniques typically identify enterotoxins-coding genes on strains that are S. aureus that have been isolated from foods contaminated by contamination. These methods come with two main drawbacks, however the first is that staphylococcal strains need to have to be separated from the food sources; and secondly the results provide information on how many or no genes that encode SEs however they don’t provide any details regarding the expression of the genes in food items. Therefore, this method is not the only method of confirming S. aureus to be the causative cause of an outbreak. The PCR approach is a precise extremely sensitive, quick method to identify all S. aureus species that are involved in food poisonings, thus providing important data.

Infections Caused by Staphylococcus aureus and Symptoms

Staph infections can cause minor skin irritations to endocarditis which is a life-threatening infection of the lining that surrounds the heart (endocardium). This is why the symptoms and signs of staph-related infections differ according to the location and extent that the infection is.

1. Skin infections

Staph-related skin infection can include:

  • Boils: One of the most commonly encountered kind of staph infection is the boil, which is a pouch of pus that forms in the hair follicle also known as the oil gland. The skin that covers the infected area is usually swelling and red. If a boil bursts open and drains, it’s likely to release the pus. Boils are most commonly found in the armpits or in the buttocks, groin, or around the waist.
  • Impetigo: This contagiousand often painful rash is caused by bacteria known as staph. Impetigo generally has large, swollen blisters that can ooze fluid and then develop a honey-colored , crust.
  • Cellulitis: Cellulitis is an infection that affects the deep layers of the skin causes swelling and redness on the skin’s surface. The appearance of sores or areas of oozing discharge could also appear.
  • Staphylococcal skin scalded syndrome: The toxins that are produced as a result of a staph-related infection can cause staphylococcal skin scalded syndrome. It is a common affliction for children and infants with this condition, it can cause flare-up, a rash and occasionally blisters. If the blisters rupture the skin’s top layer falls off, leaving a red, rough skin that appears like burning.

2. Food poisoning

Staph bacteria are among the most frequent cause of poisoning from food. It is a quick-onset illness typically within hours after eating a food item that has been contaminated. The symptoms typically disappear in a short time, and can last for as little as one or two days.

A staph infection that occurs in food doesn’t usually cause fever. The signs and symptoms that you should expect from this kind of staph infection are:

  • Nausea and vomiting
  • Diarrhea
  • Dehydration
  • Low blood pressure

3. Bacteremia

Also known as a bloodstream ailment Bacteremia happens when the staph bacteria infect the bloodstream of a person. A high blood pressure and fever are indicators of the condition known as bacteremia. The bacteria could move to areas deep inside your bodyand cause infections that affect:

  • Internal organs, like your heart, brain or your lungs
  • Muscles and bones
  • Implanted surgically like artificial joints or pacemakers for the heart.

4. Toxic shock syndrome

This life-threatening illness is caused by toxic substances produced by some strains of staph bacteria . The condition has been linked with certain kinds of tampons and cuts to the skin and surgeries. It typically manifests in sudden manner and is accompanied by:

  • A high fever
  • Nausea and vomiting
  • A rash that appears on your soles and palms that looks like a sunburn
  • Confusion
  • Muscles hurt
  • Diarrhea
  • Stomach pain

5. Septic arthritis

Septic arthritis is typically caused by the staph infection. The bacteria usually focus on the shoulders, knees and hips as well as the toes and fingers. The symptoms and signs could include:

  • Joint swelling
  • Acute pain in the joint that is affected.
  • Fever

Treatment of Staphylococcus aureus

The treatment for a staph infection can consist of:

  • Antibiotics: Your physician may run tests to find the staph-causing bacteria that cause the infection and determine which antibiotic is most effective. Antibiotics that are commonly prescribed to treat staph infections comprise some cephalosporins, such as cefazolin, nafcillin or Oxacillin vancomycin, daptomycin (Cubicin) and telavancin (Vibativ) as well as linezolid (Zyvox).
    • Vancomycin is increasingly required to fight serious staph infections as there are a variety of staph bacterium have become resistant to conventional medicines. Vancomycin, along with other antibiotics need to be administered intravenously.
    • If you’re prescribed orally administered antibiotics, make certain to take the medication as prescribed and complete all the medications recommended by your doctor. Ask your physician about indicators and signs to look out for to determine if that your condition is getting worse.
  • The drainage of a wound: If you suffer from an infection on your skin the doctor may create an incision in the area to drain the the fluid that has accumulated there.
  • Device removal: If the disease involves a device or prosthetic device, prompt elimination of your device may be required. For some devices, removal might require surgery.

Prevention of Staphylococcus aureus Infection

These common sense precautions can reduce the risk of getting Staph infections

  • Careful hand-washing is your best defense against germs. Clean your hands using water and soap for at minimum 20 minutes. Dry them off with an absorbent towel. Use another towel to stop the water faucet. If your hands don’t appear to be filthy, make use of an alcohol-based hand cleanser. Clean your hands using water and soap frequently for example, before, during , and after cooking food when handling raw poultry or meat prior to eating; after having a bathroom visit and after handling animal’s waste or an animal’s carcass.
  • Cover wounds with bandages. Keep abrasions and cuts clean as well as covered in sterile dried bandages as they heal. The pus that forms from sores that are infected usually contains staph, so covering the wounds can help prevent infections from spreading.
  • The cause of toxic shock is the staph bacteria. Tampons that remain in the tampon for long durations can become a fertile breeding ground for staph bacteria. It is possible to reduce the chance of contracting the toxic shock condition by replacing your tampon often – at minimum once every 4-8 hours. Make sure you use the tampon with the lowest absorption you can. Make sure to replace tampons using the use of sanitary napkins when you can.
  • Beware of sharing personal items, such as towels sheets, razors, sheets clothes and athletic equipment. Staph infections can infect objects and between people.
  • Staph bacteria can thrive on bedding and clothing that aren’t cleaned properly. To remove bacteria from clothing and bedding, wash them with hot water as often as feasible. Also, you can use bleach on all bleach-safe items. Drying your clothes in the dryer is more efficient than air drying, but bacteria that cause staph can be resistant to the dryer.
  • Make sure you are taking the necessary precautions to ensure food safety. Cleanse your hands before handling food items. If food will be on the table for a time, be sure that hot food stays hot — at or above 140 F (60 C) -and that cold food items remain below forty F (4.4 C) or below. Refrigerate leftovers as quickly as is possible. Clean cutting boards and counters by using water and soap.


What is the characteristic shape of Staphylococcus aureus cells?
a) Rod-shaped
b) Spiral
c) Square
d) Spherical (cocci)

Which of the following describes the arrangement of Staphylococcus aureus cells under a microscope?
a) Chains
b) Grape-like clusters
c) Pairs
d) Single

What is the size of an individual Staphylococcus aureus cell?
a) 0.5 microns
b) 2 microns
c) 1 micron
d) 3 microns

Is Staphylococcus aureus motile?
a) Yes
b) No

Which of the following is true regarding the flagellation of Staphylococcus aureus?
a) Flagellated
b) Non-flagellated

Does Staphylococcus aureus produce spores?
a) Yes
b) No

Which strains of Staphylococcus aureus possess a capsule?
a) All strains
b) No strains
c) Some strains
d) Only virulent strains

What is the result of a Gram stain test for Staphylococcus aureus?
a) Gram-negative
b) Gram-positive

Which of the following diseases is NOT associated with Staphylococcus aureus?
a) Tuberculosis
b) Food poisoning
c) Skin infections
d) Pneumonia

Which of the following is a common site for Staphylococcus aureus colonization in humans?
a) Stomach
b) Nasal passages
c) Lungs
d) Kidneys


What is Staphylococcus aureus?

Staphylococcus aureus is a type of bacteria commonly found on the skin and in the nasal passages of healthy individuals. It can cause a range of illnesses, from minor skin infections to severe diseases.

How is Staphylococcus aureus transmitted?

Staphylococcus aureus can be transmitted through direct skin-to-skin contact, contact with contaminated surfaces, or by inhaling airborne droplets from an infected person.

What types of infections can Staphylococcus aureus cause?

Staphylococcus aureus can cause various infections, including skin infections, pneumonia, food poisoning, bloodstream infections, and more.

Is Staphylococcus aureus the same as MRSA?

No, MRSA (Methicillin-resistant Staphylococcus aureus) is a strain of Staphylococcus aureus that is resistant to many antibiotics, making it more challenging to treat.

How can Staphylococcus aureus infections be prevented?

Good hygiene practices, including regular hand washing, keeping wounds clean and covered, and avoiding contact with infected individuals, can help prevent the spread of Staphylococcus aureus.

Are Staphylococcus aureus infections treatable?

Yes, many Staphylococcus aureus infections can be treated with antibiotics. However, some strains, like MRSA, are resistant to certain antibiotics and may require alternative treatments.

Can Staphylococcus aureus cause food poisoning?

Yes, Staphylococcus aureus can produce toxins in improperly stored food, leading to food poisoning symptoms like nausea, vomiting, and diarrhea.

Why is MRSA a concern in hospitals?

MRSA is of particular concern in hospitals because it is resistant to many antibiotics, can spread easily in healthcare settings, and can cause severe infections in already vulnerable patients.

Can Staphylococcus aureus infections recur?

Yes, individuals can get re-infected with Staphylococcus aureus, especially if they are in environments where the bacteria are prevalent or if they have weakened immune systems.

Is there a vaccine for Staphylococcus aureus?

As of now, there is no commercially available vaccine for Staphylococcus aureus, but research is ongoing in this area.


  • Leung, Y.L. (2014). Encyclopedia of Toxicology || Staphylococcus aureus. , (), 379–380. doi:10.1016/b978-0-12-386454-3.00539-x 
  • Martin, E. (2014). Encyclopedia of Food Microbiology || STAPHYLOCOCCUS | Staphylococcus aureus. , (), 501–507. doi:10.1016/b978-0-12-384730-0.00317-7
  • Bose, J.L. (2013). Brenner’s Encyclopedia of Genetics || Staphylococcus aureus. , (), 553–555. doi:10.1016/b978-0-12-374984-0.01473-x 
  • Foster, Timothy J. (2015). Molecular Medical Microbiology || Staphylococcus aureus. , (), 655–674. doi:10.1016/B978-0-12-397169-2.00037-8 
  • Adejuwon, Adekunle Odunayo & Ogunkanmbi, David & Adejumoke, Mary & Bisi-Johnson, Mary & Fadeyi, Bridget & Agboola, Oyinade & Adejuwon, Adebanke. (2011). Staphylococcus aureus isolated from septic caesaerean wound at Ile Ife Nigeria: Antibiotics susceptibility patterns. International Journal of Medicine and Medical Sciences. 3. 149-154. 
  • Amit Karmakar, Parimal Dua, Chandradipa Ghosh, “Biochemical and Molecular Analysis of Staphylococcus aureus Clinical Isolates from Hospitalized Patients”, Canadian Journal of Infectious Diseases and Medical Microbiology, vol. 2016, Article ID 9041636, 7 pages, 2016.
  • Silva, Wladimir Padilha da et al. Biochemical characteristics of typical and atypical Staphylococcus aureus in mastitic milk and environmental samples of Brazilian dairy farms. Brazilian Journal of Microbiology [online]. 2000, v. 31, n. 2 [Accessed 19 March 2022] , pp. 103-106. Available from: <>. Epub 04 Oct 2000. ISSN 1678-4405.
  • Adejuwon, Adekunle Odunayo & Ajayi, Adesola & Akintunde, O & Olutiola, Patrick. (2022). Antibiotics resistance and susceptibility pattern of a strain of Staphylococus aureus associated with acne. 
  • Oogai Y, Matsuo M, Hashimoto M, Kato F, Sugai M, Komatsuzawa H. Expression of virulence factors by Staphylococcus aureus grown in serum. Appl Environ Microbiol. 2011;77(22):8097-8105. doi:10.1128/AEM.05316-11
  • Cheung GYC, Bae JS, Otto M. Pathogenicity and virulence of Staphylococcus aureus. Virulence. 2021;12(1):547-569. doi:10.1080/21505594.2021.1878688

Related Posts

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

What is Karyotyping? What are the scope of Microbiology? What is DNA Library? What is Simple Staining? What is Negative Staining? What is Western Blot? What are Transgenic Plants? Breakthrough Discovery: Crystal Cells in Fruit Flies Key to Oxygen Transport What is Northern Blotting? What is Southern Blotting?
What is Karyotyping? What are the scope of Microbiology? What is DNA Library? What is Simple Staining? What is Negative Staining? What is Western Blot? What are Transgenic Plants? Breakthrough Discovery: Crystal Cells in Fruit Flies Key to Oxygen Transport What is Northern Blotting? What is Southern Blotting?
Adblocker detected! Please consider reading this notice.

We've detected that you are using AdBlock Plus or some other adblocking software which is preventing the page from fully loading.

We don't have any banner, Flash, animation, obnoxious sound, or popup ad. We do not implement these annoying types of ads!

We need money to operate the site, and almost all of it comes from our online advertising.

Please add to your ad blocking whitelist or disable your adblocking software.