التوصيف الجزيئي للبكتريا المرضية المعزولة من اخماج العيون في محافظة كربلاء

Molecular characterization of pathogenic bacteria isolated from eye inflammation in Karbala province

The eye is exposed to different types of microorganisms, and the ocular surface infection has devastating consequences, as it is not treated with antibiotics at an early stage, and these infections can lead to blindness. Therefore, the current study was conducted with the aim of investigating the most important bacterial microorganisms that cause eye infections in the holy governorate of Karbala and determine its virulence, as well as molecular investigation of the prevalence of antibiotic resistance genes and virulence genes in the bacterial isolates most common in causing bacterial eye infections. Clinically diagnosed by specialized doctors, their ages ranged between (1-75) years and for both sexes from the arrivals to Imam Al-Hassan Al-Mujtaba Hospital (PBUH), Al-Hindiya General Hospital and Al-Sayeda Zainab (PBUH) Eye Center in the Holy Karbala Governorate for the period from August 2022 to January 2023.
The results related to culture showed the presence of bacterial growth in76 (45%) samples of the total samples of ocular infections that were collected, while no growth appeared in93 (55%) samples from which41 (53.94%) Gram-positive samples were obtained, and35 (46.05%) Gram-negative samples and all bacterial isolates were diagnosed based on the morphological and microscopic characteristics of the colonies when grown on general and selective culture media, in addition to conducting several biochemical tests through which the diagnosis of the most frequent isolates was confirmed by the Vitek 2 system.
The results showed the dominance of Staphylococcus aureus with 22(28.90%) samples, followed by Staphylococcus epidermidis with19(25%) samples, then Pseudomonas aeruginosa with 18(23.60%) samples ,12 (15.70%) isolates belonging to Escherichia coli, 4(5.20%) isolates of Klebsiella pneumoniae and 1(1.30%) of isolates of Serratia marcescens.
An antibiotic sensitivity test was carried out for the most frequent bacterial isolates in this study, which are Staphylococcus aureus and Pseudomonas aeruginosa, using the Vitek2system, as most of the bacterial isolates were multi-resistant to antibiotics, as all Staphylococcus aureus isolates were 100% resistant to Amoxicillin antibiotics. Amoxicillin \ Clavulanic Acid, Benzylpenicillin while it was found that Rifampicin, Linezolid, Teicoplanin and Tigecycline are the most effective against these bacteria, and the insulation of Pseudomonas aeruginosa was 100% resistance towards Amoxicillin, Amoxicillin \ Clavulanic Acid, Piperacillin while she was sensitive to Colistin, Imipenem and Meropenem.
In this study, significant differences were found between the age groups of patients at the level of probability (p = 0.021), and the age group (25-49) years was the most infected, and the gender and place of residence (rural or arban) had an effect on the distribution of bacterial infections among people with infection The eyes, as infections were higher in males and also in the arban, and a clear significant difference appeared at the level of probability (p = 0.045 and p = 0.028), respectively, between the distribution of the number of bacterial infections according to the site of infection in the eye, whether it was conjunctiva, cornea or eyelids, while there was no difference Significant between the type of bacteria isolated and the site of bacterial infection in the eyes at the level of probability (p = 0.034).
As for the studied risk factors represented in trauma, ocular surface diseases such as dry eyes, wearing contact lenses, as well as systemic diseases such as diabetes mellitus and respiratory infections, it was observed through the results that there is a significant correlation at the level of probability (p = 0.012) between these factors and the occurrence of infection. bacteria in the eyes.
There was also a significant correlation between the studied risk factors and the sites of bacterial infection in the eye from the conjunctiva, cornea and eyelids. Likelihood level (p = 0.742).
Bacterial isolates possessed important virulence factors related to eye infections, including their ability to produce biofilms and hemolytic toxin. The current statistical results showed a correlation between the ability of bacterial isolates to produce biofilms and the site of bacterial infection in the eye, while there was no significant correlation between the ability of bacterial isolates to kill Hemolytic toxin production and ocular site of infection.
The polymerase chain reaction (PCR) technique was used to conduct an investigation test for the presence of genes encoding antibiotic resistance, and genes encoding for virulence factors for all isolates of Staphylococcus aureus and Pseudomonas aeruginosa to find out the extent and distribution of these genes in the bacterial isolates that infect the eye. The results showed that 95.4% of the isolates Staphylococcus aureus bacteria carrying the mecA gene through the appearance of a PCR product of size 310 bp, which is resistant to methicillin MRSA, and that 72.7% carry the gene ermA, and thus it has resistance to anti-macrolides through the emergence of a PCR product of size 645 bp, and thus Staphylococcus aureus bacteria acquired multiple resistance to antibiotics. As for the important virulence genes in causing eye pathogenesis, the hlb gene and SEA, by polymerase chain reaction, it was found that the PCR output was 309 bp and 102 bp, respectively, for Staphylococcus aureus isolates, with a percentage of 77.2% and 68.1%, respectively.
As for the virulence genes of Pseudomonas aeruginosa, the presence of the exoA and LasB genes showed 100% through the appearance of a PCR product with a size of 396 bp and 300 bp, respectively.
The current study included that Gram-positive bacterial species are more common than Gram-negative bacteria in causing different eye infections, and the studied bacterial isolates possess important virulence factors represented by hemolysin production, biofilm formation, and virulence genes that increase the severity of bacterial infection in the eye as well. About having resistance genes that helped her resist antibiotics.