The signs of conjunctivitis caused by bacteria can be eye redness and itching. Here we tell you everything you should know about this disease.

Bacterial conjunctivitis can present with symptoms such as red eyes and purulent discharge from the eye. This happens because an infection settles in the conjunctive layer, which is a mucous membrane that lines the inside of the eye.

According to the Centers for Disease Control and Prevention (CDC), conjunctivitis is one of the most common pathologies globally and its treatment is easy. In general, there are no complications in most cases.

Do you know what the origin of bacterial conjunctivitis is? Do you know how to avoid them? Despite its low severity, this disease presents an annoying clinical picture. That is why here we tell you everything you should know about it.

Bacterial conjunctivitis and microbiome

As various studies point out, the human being has evolved in a close and constant association with the complex microbial flora that is located in her body. Any surface in contact with the exterior is susceptible to the colonization of microorganisms. The nose, mouth, entire gastrointestinal tract, skin, and sexual organs are the rule, but the eyes are no exception.

The normal microbiome or microbiota is the set of microorganisms, aggregated in colonies, that are found in any part of the human body, grouping together by affinity and functionality. The clearest example is that of the intestinal microbiota, but the reality is that there are bacterial colonies in many more areas of our body.

Ocular microbiota

According to the American Academy of Ophthalmology, the bacterial flora of the eye is found in the connective layer, a mucous membrane that lines the inside of the eye, and in the cornea, the transparent front part that protects the iris.

Compared to other systems, the eye microbiome is relatively poor in bacteria. According to various bibliographic sources, this could be due to the fact that tears contain lactoferrin, a protein with antimicrobial capabilities.

Thus, only a few microorganisms make up the eye microbiome. Among them are species of the following genera: Staphylococcus, Streptococcus, Propionibacterium and Corynebacterium.

These bacteria are in symbiosis with humans, since they do not cause any harm to them and prevent other pathogens from colonizing the ocular surface in normal situations. Thus, a coexistence establishes that is favorable to both.

What is bacterial conjunctivitis?

As we have said before, bacterial conjunctivitis is an infection that occurs due to the entry of pathogens of bacterial origin into the conjunctive layer of the eye. This generates an inflammation of the connective tissue, which produces the characteristic eye redness.

A study in the journal Anales de Pediatría stored samples from 596 patients diagnosed with acute conjunctivitis in the Community of Madrid (Spain). The results were the following:

A total of 428 types of bacteria were isolated from all the samples analyzed.

Bacteria Aemophilus influenzae (44.8%) and Streptococcus pneumoniae (30.6%) were the most prevalent.

Strains of Staphylococcus aureus (7.5%), Streptococcus group viridans (7.2%), Moraxella catarrhalis (6.8%) and Enterobacteriaceae (4.2%) were also represented.

Two pathogenic bacteria were isolated in 15% of the samples.

Thus, this study shows that A. influenzae and S. pneumoniae are the causes of conjunctivitis in most cases. In addition, it was discovered that the first bacteria was very frequent among children from 7 to 14 years old, which indicates a certain influence of age on the affinity of one or another microorganism.

Signs of conjunctivitis caused by bacteria

Although there are four causes of conjunctivitis (viruses, bacteria, allergens, and irritants), the clinical picture is very similar in all cases. It is the doctor’s job to suspect and find the causative agent. Among the most common signs of conjunctivitis we find the following:

  • Pain in the eyes, between moderate and strong.
  • Light sensitivity.
  • Intense redness in the eyeball.
  • Gritty feeling when blinking.
  • Burning.
  • Increase in the amount of tears.
  • Secretion and tearing of substances of greenish or yellowish color.

In general, bibliographic sources cite that it is a self-limited disease, that is, that the body can solve it without major problem. Still, there are antibiotic agents for possible clinical complications, either due to the bacteria itself or because the person does not have an immune system effective enough to cope with the infection.


The review article cited above lists some of the most widely used antibiotics in bacterial conjunctivitis. These come in the form of ointment or eye drops, and you apply them every 3 to 4 hours or 6 to 8 hours, depending on medical indications. They are as follows:

  • Quinolones.
  • Aminoglycosides.
  • Tetracyclines.
  • Macrolides.
  • Trimethoprim.
  • Fusidic acid.

It is important to clarify that these medications are only useful when dealing with bacterial strains. If conjunctivitis is viral or due to an allergen, it won’t do. That is why it is necessary, in the most serious cases, to promptly diagnose the origin of eye discomfort before resorting to a specific drug.

What to remember?

Bacterial conjunctivitis is a very common disease that usually resolves on its own and does not have serious effects on the body. Its most common symptoms are reddish coloration of the conjunctiva, burning when blinking and purulent discharge from the eye.

Although benign, the clinical picture it generates is quite annoying. Therefore, it is essential to take correct general hygiene measures. That is, wash your hands regularly, and avoid rubbing your eyes continuously. And, do not share eye material (makeup or contact lenses) with other people.

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source : thehealthyville.com