Investigating the antibiotic resistance pattern of Staphylococcus aureus isolated from clinical samples of patients hospitalized in the special care departments of Ahvaz teaching hospitals

One of the most significant harmful microorganisms is Staphylococcus aureus . Due to the rise in the resistance of this bacteria to antibiotics and the lengthening of hospitalized patients' treatments, one of the causes of infection and mortality among patients hospitalized in special care units of hospitals. In this cross-sectional descriptive study, samples of 113 S. aureus isolates were taken from patients who had spent 4 months in the special care units of Ahvaz teaching hospitals. These samples were then tested using antibiograms for oxacillin, cefoxitin, linezolid


Introduction
The most significant genus in the medically significant Micrococcaceae family is Staphylococcus.Staphylococcus is a grape cluster-shaped, facultatively anaerobic, grampositive cocci [1][2][3][4].Staphylococcus is connected to 80% of purulent infections and is the second leading cause of hospital infection among patients after Escherichia coli.The surface of a mammal's body and its surroundings are where staphylococcus is primarily found.An infection is brought on by this bacteria, an opportunistic and invasive pathogen, penetrating the tissue if the host's body's protective barrier is compromised by an injury.Without treatment, the infection spreads throughout the body, causing septicemia, acute endocarditis, bacteremia, and extensive skin infections [2,3,5,6].
Catalase, coagulase, and hyaluronidase are a few of the microorganism's enzymes that have been successful in the pathogenesis of surgical wound infections, venous catheter site infections, soft tissue infections, endocarditis, joint infections, toxic shock syndrome, and bacteremia, among other conditions [7,8].
The presence of venous catheters and tracheostomies, as well as regular contact with healthcare facilities like hospitals, are all factors in the colonization of MRSA infection.S. aureus strains have become more resistant as a result of prolonged hospitalization, patient surgery, and the indiscriminate use of antibiotics, which has led to an increase in the number of hospital infections brought on by this bacterium in recent years as compared to earlier years.The past has brought up [9,10].
Due to frailty, a weakened immune system, and vascular manipulations, patients in special care units are more likely to develop invasive S. aureus infections than patients in other departments.In this situation, the patients are a source of infection for the staff who provide care and other individuals [11,12].In the current study, the prevalence of S. aureus resistance to the antibiotics oxacillin, cefoxitin, ciprofloxacin, erythromycin, clindamycin, trimethoprim, sulfamethoxazole, linezolid, penicillin, and vancomycin in hospitalized patients was investigated.This was done in an effort to stop the spread of infection and ensure proper hospital infection treatment by taking the necessary steps every patient is essential and crucial.This study was carried out to look at the S. aureus resistance trend in Ahvaz teaching hospitals.

Materials and Methods
In this cross-sectional analytical procedure, patient samples from their blood, urine, and wound cultures were cultivated on blood agar and EMB as soon as they entered the microbiology lab, and were then incubated at 37 degrees for 24 hours and then read if positive.In order to conduct phenotypic tests for warm color, catalase, mannitol salt agar, DNase, and tubular coagulase, the creamywhite, gray-colored colonies were removed from the culture media after cultivation.Following the identification of S. aureus, 113 samples were isolated and kept at -70°C and glycerol in a TSB medium for 4 months.
The research period was from the beginning of April to the end of July 1402, and it was based on 113 samples of S. aureus isolated from patients hospitalized in the special care departments of Ahvaz teaching hospitals (Imam, Razi, Sina, Bagai, Taleghani, Abu Zoro, Golestan).Labs for microbiology received the samples.With 113 samples, the appropriate sample volume was obtained using the agar disk diffusion technique, and Oxacillin (30 micrograms) was used to isolate the methicillin-resistant S. aureus strain based on CLSI for cefoxetine antibiotics.The antibiograms were carried out (Figure 1) on Hilton Muller Agar medium using sterile tweezers to retrieve and culture a sterile swab or loop of turbidity comparable to the normal turbidity of half McFarland (108 × 1.5 bacterium cells per milliliter).The environment's surface was covered with antibiogram disks, which were incubated for 24 hours at 37°C with halo formation and classified by Kirby-Bauer as sensitive, semisensitive, and resistant.All MRSA isolates were tested for resistance to antibiotics after being given the desired MRSA, including vancomycin (30 micrograms), linezolid (30 micrograms), ciprofloxacin (5 micrograms), clindamycin (2 micrograms), trimethoprim sulfamethoxazole (1 microgram), penicillin (10 micrograms), and erythromycin (15 micrograms).Patten Teb Company was then cultured on Muller's medium.This procedure was the same as the one described above for these antibiograms in that it was placed on Hilton Muller Agar medium with a sterile swab or sterile loop of turbidity equivalent to the standard turbidity of half McFarland (1.5 x 108 bacterial cells per ml), cultured, and using Antibiogram disks were placed on the surface of the medium with sterile forceps and incubated for 24 hours at 37°C.

Results
Out of 113 samples of S. aureus that were isolated, the study's findings revealed that males had the highest prevalence of the bacteria (54.86%), and males over the age of 45 had the highest prevalence (32.25%), while males between the ages of 31 and 45 had the lowest prevalence (19.6%) (Table 1).
According to the findings, Golestan Hospital had the highest frequency of S. aureus (21.23%) (Table 2).In blood culture samples, penicillin had a 100% success rate, clindamycin had an 88.9% success rate, ciprofloxacin had an 81.81% success rate, erythromycin had an 80.7% success rate, and trimethoprim had a 73.52% success rate in inhibiting MRSA growth.Periodic exams should include blood since it is crucial.
According to the findings (Table 3), S. aureus was most prevalent in blood samples (49.55%) and least prevalent in urine samples (32.12%).If 90% of MRSA detected in blood samples were responsive to the antibiotic vancomycin, then all strains of S. aureus tested positive for linezolid sensitivity (Table 4 and  5).

Discussion
Out of 113 S. aureus isolates from patients hospitalized in ICU wards, 83 (73.45%) were methicillin-resistant strains, and all of these isolates were 100% sensitive to linezolid antibiotic.In contrast, all penicillin antibiotics showed 100% resistance, while vancomycin antibiotic showed 90.36% sensitivity, ciprofloxacin antibiotic showed 90.36% resistance, and clindamycin antibiotic showed 86.15% resistance.
The findings of Khazaei et al.'s study, S. aureus resistance to vancomycin: a six-year study 1385-1390, revealed that 5736 staphylococcus samples were isolated from all the samples that were delivered to the lab.3987 of them (69.5%) had staphylococcus coagulase positive cases.According to the study, 3897 instances (68.1%) of S. aureuspositive cases were found in urine samples, 966 cases (16.9%) in blood samples, and the remaining cases were found in samples from wounds, throats, and sputum.Vancomycin's antibiotic pattern analysis revealed 4.8% resistance [13].With regard to antibiotic resistance to vancomycin, this is consistent with the current study.
A phenotypic and molecular analysis of vancomycin-resistant S. aureus clinical isolates collected from Rasht hospitals during a six-month period (Feb.1994, Jul.1995) has been done.There are 67 different strains of S. aureus.Chloramphenicol 10.5%, gentamicin 25.37%, tetracycline 37.32%, vancomycin 38.80%, oxacillin 44.70%, and penicillin 100% had the highest rates of antibiotic resistance in the disk diffusion technique test.22.4% of the samples used in the broth macrodilution technique had vancomycin resistance.VanA gene PCR results showed no VanA gene band [14].This research found a 100% penicillin resistance rate, which is consistent with the current study.
Research has been done to identify the pattern of antibiotic sensitivity in S. aureus strains obtained from human clinical infections and to monitor genes expressing antibiotic resistance.The phenotypic analysis of the antibiotic resistance pattern of S. aureus strains revealed that the antibiotics penicillin (90%), tetracycline (76%), methicillin (64%) and ampicillin (55%) have the highest levels of resistance, while nitrofurantoin (8%) and vancomycin (14%) have the lowest levels.The strains had 89% of the tetM gene, according to molecular analyses.Following that, the presence of the genes mecA (58%), ermA (40%), msrA (36%), aacA-D (24%) and tetK (13%) was associated with the greatest frequencies [15].This study's findings were comparable to those of this one.
Phenotypic techniques have been used to identify methicillin-resistant S. aureus and bacteria that produce ESBL after investigating the antibiotic sensitivity pattern of microorganisms isolated from patients hospitalized in PICU.Escherichia coli (24 instances), Pseudomonas aeruginosa (3 cases), and S. aureus (8 cases) were found to be the most frequently isolated microorganisms from all clinical samples given to the lab, according to the findings.Seven (65%) of the eight S. aureus strains that were found in the various clinical samples that they were isolated from were MRSA.52 isolates of Gram-negative bacteria included 5 (3.7%)ESBL strains [16].In terms of the proportion of methicillin-resistant S. aureus isolates, this study is compatible with the previous research [16].
Its goal is to look into the prevalence and distribution of MRSA strains that are resistant to antibiotics at the Imam Reza (AS) Mashhad Hospital.The findings of this investigation revealed that 925 (12.6%) strains of S. aureus were found in the patients out of a total of 7335 germs isolated from patients hospitalized in Imam Reza Hospital, Mashhad.There were 382 (41.7%) instances of MRSA.Blood and wound culture samples were used to isolate the majority of MRSA isolates.Adalatian, Internal Affairs, Burns, and Cardiology emergency departments had the highest MRSA prevalence rates [17].The proportion of methicillin-resistant S. aureus strains in blood and wound samples is consistent and aligned when compared to the current investigation.
Ayat Alleh Mousavi Hospital in Zanjan patients' clinical samples of S. aureus were examined for antibiotic resistance patterns.The findings revealed that out of 66 samples obtained, every single sample was vancomycin sensitive.Cotrimoxazole was 90.9% sensitive, cefazolin was 4.86% sensitive, clindamycin was 81.8% sensitive, cloxacillin was 2.71% sensitive, and the D-test was positive in 5.5% of samples [5].This research's level of clindamycin sensitivity was consistent with the current study.In Ghafouri's study, the pattern of antibiotic resistance in bacteria isolated from clinical samples of hospitalized patients was examined.During the course of the investigation, 126 patients with nosocomial infections were discovered.Escherichia coli, coagulase-negative Staphylococcus, Candida, coagulase-positive Staphylococcus, Enterobacter, Klebsiella, Citrobacter, Pseudomonas aeruginosa, Acinetobacter, Gram-positive bacillus, Enterococcus, and Gram-negative coccobacillus were the most frequently isolated microorganisms (commonly 20.The isolated microbes varied in their antibiotic resistance.In Acinetobacter, the greatest level of resistance was noted.Acintobacter was completely resistant to ciprofloxacin, amikacin, and gentamicin in all instances [18]. The incidence of methicillin-resistant S. aureus carriers and their pattern of drug resistance among Torbat Heydarieh hospital staff members were examined in 2013.The results showed that 28 out of the 130 individuals examined (21.5%) had S. aureus in their nostrils.In comparison to other departments, the women's department had the fewest S. aureus carriers while the critical care and laboratory departments had the most.Only the age of the personnel and the S. aureus carrier were discovered to have a significant association among the factors under investigation.Penicillin (100 percent), gluxacillin (42.9 percent), and cotrimoxazole (5 percent) had the greatest and lowest rates of resistance, respectively.In this investigation, the oxacillin agar technique revealed methicillin resistance in 14 samples (10.8%) [19].The degree of penicillin resistance in this investigation was wholly consistent with that in the current study.
Antibiotic resistance in S. aureus isolated from Imam Reza Hospital, Kermanshah, including its incidence and patterns.The findings demonstrated that the majority of S. aureus cases (43.7%), blood samples (40.1%), and urine samples (23.9%) were isolated from other sources.Erythromycin, penicillin G, ofloxacin, cefoxitin, clindamycin, and piperacillin were the antibiotics with the highest rates of resistance.With sensitivity rates of 93.3 and 81.8%, respectively, vancomycin and teicoplanin were the most effective drugs against S. aureus [21].Regarding sensitivity and resistance to the antibiotics cefoxitin, clindamycin, and vancomycin, this investigation was comparable to the current study.
The infection control committees of each hospital should review the antibiotics used in the hospital in terms of resistance and periodically put them on the chart in the special care departments to prevent the prescription of antibiotics, per the report obtained in the teaching hospitals of Ahvaz.The physicians in the department should use strong opposition to stop it.

Conclusion
The findings demonstrated a significant rise in vancomycin antibiotic resistance, which poses a significant concern in the management of infections brought on by resistant strains.Therefore, one should avoid prescribing without a prescription and inappropriate use of accessible antibiotics in order to prevent the development of resistance to the stated antibiotics as well as other common antibiotics.The results of the current study also revealed that there is no connection between antibiotic resistance and the frequency of methicillin-resistant S. aureus in the department, sampling site, or hospital; however, when it comes to the relationship with age and gender, the resistance rate was higher in men over 45 years of age than it was in men under 45.According to the judgment of the location of the body sample, more blood samples were taken there than in other research.

Table 1 .
Relationship between gender and age of patients in the spread of S. aureus

Table 2 .
The number of samples and hospitals where S. aureus was isolated

Table 3 .
Status of antibiotics examined in blood, urine and wound samples

Table 4 .
Identification of MRSA by disk diffusion method

Table 5 .
Antibiotic resistance pattern of methicillin-resistant S. aureus (MRSA) compared to the studied antibiotics