# The Importance of Gram-Negative Rods in Chronic Rhinosinusitis
## 4 Discussion
In the first state, _Corynebacterium_ species were dominant; in the second, _Staphylococcus_ spp. prevailed, and in the third, the microbiota was dominated by _Streptococcus_, _Haemophilus_, _Monaxella_, and _Pseudomonas_ species. These three microbiota states were observed in healthy individuals and those with sinonasal diseases. However, the authors noted geographical differences: in Europe, _Staphylococcus_ spp.-dominated microbiota was more prevalent, whereas in Asia, the first microbiota type, characterized by a predominance of _Corynebacterium_ spp., was more common [52]. The results of our study showed that the dominant microorganisms isolated from the sinuses of CRS patients were Gram-positive cocci, primarily of the _Staphylococcus_ genus, which is consistent with findings from other studies [53; 54; 50; 55; 48]. Among the isolated coagul-negative staphylococci (CNS), _S. epidermidis_ was the most prevalent. However, since this microorganism was also frequently isolated from patients in the control group, the conclusions we can draw regarding the role of _S. epidermidis_ as a pathogen are limited. Nevertheless, our results confirm the frequent occurrence of CNS, particularly _S. epidermidis_, in samples taken from patients with CRS, as reported by other authors [56; 46; 50]. Furthermore, the presence of _S. aureus_, in both healthy and diseased individuals suggests that certain bacteria may exhibit pathogenic or commensal behavior depending on the specific strain, genetic expression, overall abundance, and interactions with other microorganisms within the mucosal community [34]. An important point of interest is the occurrence of facultatively anaerobic Gram-negative rods in the clinical material collected from patients with CRS. The reported incidence of _Enterobacterales_ rods varies and, depending on the study [57; 58; 59; 60; 35]  
In our study, _Enterobacterales_ were present in 32% of patients with secondary CRS and 29% with primary CRS, representing 20% and 17% of the total isolates, respectively. The results indicated that the genus richness of the primary CRS group was slightly higher than that of secondary CRS, with _E. coli_ being the dominant species in both groups. The \"overrepresentation\" of _E. coli_ in CRS patients was also confirmed using 16S rRNA sequencing by [PERSON] et al. [61]. [PERSON] et al. also drew attention to Gram-negative rods associated with CRS. The authors described three cases of CRS patients from whom _E. coli_ were isolated [62]. These patients did not respond to antibiotic treatment targeting the classical pathogens commonly associated with sinus infections. The isolated _E. coli_ strains exhibited sensitivity to antibiotics used in the treatment of Gram-negativeinfections and possessed several virulence factors typically found in strains from urinary tract infections [62]. In our study and reports from other authors, Gram-negative bacilli are rarely isolated from individuals without CRS. Therefore, it is suggested that one of the causes of disease symptoms may be lipopolysaccharide, the main component of the cell wall, which can trigger mucosa inflammation and cause tissue remodeling [23]. [PERSON] et al. isolated Gram-negative rods more frequently from CRSwNP patients than from patients without polyps [50]. Similarly, [PERSON] found large numbers of _E. coli_ in CRSwNP patients with asthma [63]. In a study by [PERSON] et al., antibiotic use, asthma, and prior surgery influenced the sinus microbiome. Antibiotics and asthma were associated with significant reductions in bacterial diversity and increased abundance of _S. aureus_, whereas surgery was associated with decreased species richness. Prolonged, repeated antibiotic administration may reduce the complexity of the microbial community and lead to the emergence of a few dominant bacteria. Therefore, this may be one of the reasons for isolating different species of Gram-negative rods from clinical specimens [64]. In our studies, _Enterobacterales_, especially _E.