Study population
This retrospective descriptive cross-sectional survey was carried out in the pediatric intensive care unit (PICU), pediatric hematology, and other pediatric wards of Besat Hospital, Hamadan, during 6 months of 2016.

Inclusion criteria
During the study period, all patients who had eligible criteria for each kind of nosocomial infection were enrolled in the study using a checklist. The definition of nosocomial infection was similar to that provided by the Centers for Disease Control and Prevention (CDC) (12).  To determine the infection type (nosocomial or community-acquired) and clinical samples (tracheal culture, urine, blood, wound, and other samples), all patients (Patients and clinical specimens) were evaluated by the infection control team.

Sampling method
Census sampling method was used for sampling. Thereafter, cultural process and susceptibility testing were performed on clinical specimens which were sent to the laboratory. All patients hospitalized with an infection and positive culture without the history of recent hospitalization were separately recorded and analyzed to compare the pattern of antibiotic resistance of HAIs with CA infections during this period.

Detection of microorganisms
After delivering clinical samples to the laboratory, they were immediately cultured on proper media, such as Blood agar, MacConkey agar, EMB, and Nutrient agar and then incubated overnight.  After 24 h, the presence of cocci, Bacillus, and Gram-positive/negative bacteria was detected using macroscopic (Colonies shape) and microscopic (Gram-staining) techniques. Subsequently, Catalase/ Oxidase, OF, TSI, Urease, IMViC tests growth on mannitol Salt Agar medium 6%, Growth/in the presence of salt, growth at 25, 37, and 42°C and other microbiology and biochemical tests were used to identify the genus and species of bacteria.

Antibiotic susceptibility testing
To intent upon antimicrobial susceptibility pattern, the Kirby Bauer Disk Diffusion test was utilized as it was recommended in the CLSI /M100-S27 guidelines (13). Cefoxitin disk diffusion was used to determine methicillin resistance S. aurous (MRSA). In addition, E-test was used to determine the susceptibility of bacteria against Meropenem, Colistin, and Vancomycin. The antibiotic disks which were used in the current study were provided from MAST Company (UK). These antibiotic disks included Ceftriaxone (30µg), Ceftazidime (30µg), Cefepime (30µg), Gentamicin (10µg), Ciprofloxacin (5µg)), Co-trimoxazole, Piperaciline-tazobactam, Ampi-Sulbactame (20/10µg), Imipenem (10µg), Meropenem (10µg), Colistin(10µg), Cefazolin (30µg), Erythromycin (30µg), Clindamycin(30µg), Cefoxitine (30µg), Cloxacillin (30µg), and Vancomycin.

Statistical analysis
The obtained data were analyzed in SPSS software (version 16.0) using descriptive statistics. The Ethics Review Board of the Hamadan University of Medical Sciences approved the study. (IR.UMSHA.REC. 1395.352).

Characterization of study participants
The present study was conducted on 43 patients who were hospitalized for more than 48 h in Besat Hospital, Hamadan, Iran, as well as 68 individuals who were hospitalized in the same wards due to community-acquired infections. Notably, 42.6% and 60.5% of patients with community-acquired infections and hospital-acquired infections were males, respectively.  The mean age of patients with community-acquired infection and hospital infection was reported as 2.17 and 5.27 years, respectively. The most collected samples from patients with community-acquired infections were urine samples with a frequency of 50 (73.5%). On the other hand, most samples achieved from patients with hospital-acquired infection were related to blood samples (BSI) with the occurrence of 30 (69.8%).

Main results
The most common organisms recovered from community-acquired and hospital-acquired infections were E. coli and S. aurous with a prevalence of 67.6% and 30.2%, respectively (Table 1). As evidenced by the findings, the least resistance in the community-acquired infections against E. coli was related to Colistin and Meropenem with a prevalence of 0%, followed by Imipenem and Cefepime with the prevalence of 2.2% and 8.9%, respectively. Conversely, the highest resistance was pertinent to Co-trimoxazole with a frequency of 64.4%, followed by ceftriaxone (27.6%). Klebsiella has a high sensitivity to most antibiotics and showed the highest resistance to Co-trimoxazole (75%). Among hospital-acquired infections caused by E. coli, the minimum resistance was against Colistin, Meropenem, and Gentamicin with a frequency of 0%, followed by piperacillin/tazobactam (10%). Moreover, the highest resistance in E. coli was against Co-trimoxazole with a prevalence of 40%. In addition, in Klebsiella pneumonia isolated from hospital-acquired infections, the minimum resistance was against Colistin, Imipenem, Meropenem, and Piperacillin-tazobactam (0%), and 42.9 % of isolates were resistant to Co-trimoxazole.
In Acinetobacter baumannii, the least resistance was to ciprofloxacin with the occurrence of 16.6%, followed by meropenem, gentamycin, colistin, and piperacillin-tazobactam with the frequency of 33.2%. While, the highest resistance was against Co-trimoxazole (66.7%), (Table 2). In community-acquired infections caused by S. aurous, the least resistance was to vancomycin (0%), followed by ciprofloxacin (18.2%), and the highest resistance was to clindamycin with a prevalence of 54.5%. In the case of hospital-acquired infections, Vancomycin was the most effective antibiotic for infections caused by S. aurous and the most resistance in this organism was observed against clindamycin with a prevalence of 53.8%. About 36.4% of S. aurous which were retrieved from community-acquired infections was MRSA, as compared to 42.6% of S. aurous isolates which were recovered from hospital-acquired infections. Of these community-acquired MRSA isolates, 45.5% were resistant against Co-trimoxazole and 66.6% were resistant to clindamycin.
Notably, no resistance was reported against vancomycin and ciprofloxacin in S. aurous isolated from both community and hospital-acquired infections (Table 3). In community-acquired UTI caused by E. coli, the least resistance was to imipenem, meropenem (2.9%), and piperacillin-tazobactam (8.9%), while the highest resistance was related to Cotrimoxazole (74.3%), followed by ceftriaxone (28.6%). In hospital-acquired UTI caused by Escherichia coli (E. coli), the lowest resistance was to Meropenem, piperacillin-tazobactam, and gentamicin (0%), and the highest resistance was to Co-trimoxazole (90%). In Klebsiella produced community-acquired infection, 100% of isolates were resistant to Co-trimoxazole.
In general, in Gram-negative bacteria caused by community-acquired-UTI, the highest resistance was to Cotrimoxazole with a prevalence of 71.4%, followed by gentamycin and ceftriaxone with a prevalence of 24.5%, and with no resistance against Colistin and Meropenem. Moreover, the resistance rates against Imipenem and Cefepime were reported as 2% and 8.2%, respectively. The antibiotic susceptibility results of Gram-negative bacteria which cause bloodstream infection (BSI) indicated that the highest resistance was to Ceftriaxone in community-acquired infections with a prevalence of 31.6%, followed by tazocin and gentamycin with the prevalence of 10.5%. However, no resistance was reported to Colistin. Nonetheless, in Gram-negative bacteria which caused hospital-acquired infections, the most resistance was reported to Ceftriaxone with a frequency of 37.5% and the least resistance was to Colistin, gentamycin, and tazocin with the prevalence of 12.5%.
In Gram-positive organisms which caused community-bloodstream infections, no resistance was observed to vancomycin (0%). Moreover, the resistance rate against ciprofloxacin and cefoxitin was estimated at 16.7%, whereas the highest resistance was to clindamycin (50%). On the other hand, in Gram-positive organisms which caused hospital-acquired bloodstream infection, the most resistance was to erythromycin with a prevalence of 53.8%, followed by cefoxitin with the prevalence of 46.2%. Nevertheless, no resistance was observed against vancomycin (0%).  Frequencies of MRSA isolates in community and hospital-acquired bloodstream infections were reported as 16.7%, and 46.2%, respectively.

Discussion

In The present study demonstrated that the most common organisms isolated from both community and hospital-acquired infections in pediatrics patients were E. coli and S. aurous with a prevalence of 67.6% and 30.2%, respectively. These findings were inconsistent with the studies conducted in India (14) and Turkey (15) which found that E. coli and S. aurous were most prevalent. Moreover, the highest resistance was observed against Co-trimoxazole in E. coli which caused both community-acquired and hospital-acquired infections. Therefore, due to its high resistance, Co-trimoxazole is not recommended as the mainstay of treatment for empirical therapy in both types of infections. This could be due to indiscriminate prescribing of these antibiotics to pediatric outpatients.
 

Table 1. Oligonucleotide primers used for RT-PCR


Table 2. Results of susceptibility test in gram negative organisms based on the infections types



Table 3. Results of susceptibility testing in gram positive organisms based on the infections

In The present study demonstrated that the most common organisms isolated from both community and hospital-acquired infections in pediatrics patients were E. coli and S. aurous with a prevalence of 67.6% and 30.2%, respectively. These findings were inconsistent with the studies conducted in India (14) and Turkey (15) which found that E. coli and S. aurous were most prevalent. Moreover, the highest resistance was observed against Co-trimoxazole in E. coli which caused both community-acquired and hospital-acquired infections. Therefore, due to its high resistance, Co-trimoxazole is not recommended as the mainstay of treatment for empirical therapy in both types of infections. This could be due to indiscriminate prescribing of these antibiotics to pediatric outpatients.
As evidenced by the obtained results, no resistance was found against Colistin and Meropenem in Gram-negative microorganisms which caused the community-acquired infections, followed by Imipenem and Cefepime with the prevalence of 2.2%, and 8.9%, respectively. Consequently, Meropenem can be used as the first-line treatment empirically in critically ill patients with HA-sepsis until obtaining the results of culture and susceptibility test. However, in CA-infections, cefepime can be used as an acceptable antibiotic in the empirical regime. In A. baumannii, the minimum of resistance was reported against ciprofloxacin which was probably owing to the no or at least use of this antibiotic in the pediatric ward. In CA and HA-infections caused by Gram-positive cocci, no resistance was observed against vancomycin; however, 36.4% of CA-S. aurous and 42.6% of HA-S. aurous were resistant to cefoxitin (MRSA).In addition, the highest resistance in S. aurous was reported against clindamycin which indicates that these medicines should not be prescribed in empirical therapy.
There exists a high resistance of methicillin in MRSA strains with a high percentage of prevalence in hospitalized patients suspected to Gram-positive infectious agents. In this case, vancomycin empirical prescription and utilization should be undertaken until getting the results of culture and susceptibility testing. In community-acquired infections which are caused by E. coli, the highest resistance was to Co-trimoxazole with a frequency of 64.4%, followed by Ceftriaxone (27.6%). In line with these results, a study conducted in Tehran in 2007 found that the most common organism was E. coli with a prevalence of 51.4%, and the most resistance was against Ampicillin and the least one was to ciprofloxacin, ofloxacin, and amikacin (16). Whereas, in a study performed in Bahrami Hospital, Tehran, the most common reported isolates were P. aeruginosa (24.3%) and Klebsiella pneumonia (18.6%) (17). The prevalence of pathogenesis is roughly similar in the distinct regions all around the world despite the fact that antimicrobial resistance patterns are markedly different.
This difference in antibiotic resistance patterns in various parts of the world is attributed to the immoderate and infelicitous antibiotics utilization, geographical difference, and the difference in prescribing the antibiotic regimes (15). E. coli was recognized as the most prevalent organism in UTI which is consistent with the results of previous studies (18,19). Moreover, our findings revealed that E. coli isolated from UTI in both CA and HA infections had the same antimicrobial pattern since Imipenem was the most active agent against E. coli and the most resistant one to Co-trimoxazole. In the present study, 100% of K. pneumonia isolated from community-acquired infections were resistant to Co-trimoxazole. Whereas, all isolates were susceptible to almost all antibiotics in acquired-hospital infections. In accordance with these results, a study conducted by Yuksel et al. (2006) conducted on UTI in Turkey revealed that the most common causative agent was E. coli, followed by K. pneumonia. Moreover, resistance to ampicillin and Co-trimoxazole in all isolates was another noteworthy result of the mentioned study (20). In community-acquired UTI, we reported 100% resistance against Co-trimoxazole; nonetheless, it should be omitted from the drug regime in the treatment of children-UTI. Instead, the low level of resistance to Imipenem and Meropenem can be a reasonable alternative in the treatment of UTI (20, 21).
In community-acquired bloodstream infection (CA-BSI) caused by Gram-negative bacteria, the highest resistance was reported against ceftriaxone with a prevalence of 31.6%, while no resistance was described against Colistin. Whereas in hospital-acquired bloodstream infection (HA-BSI), the most resistance was against ceftriaxone with a prevalence of 37.5% and the lowest was against Colistin/gentamicin and tazocin with a frequency of 12.5%. Consequently, the prescription of gentamicin or Piperacillin/Tazobactam rather than ceftriaxone can be the proper choice in BSI cases. Furthermore, in Gram-positive organisms which caused CA-BSI, the least resistance was against vancomycin (0%), while the highest was to clindamycin (50%). Nevertheless, among Gram-positive organisms which developed HA-BSI, the most resistance was to cefoxitin with a prevalence of 46.2% and the least resistance to vancomycin (0%). Therefore, in patients with HA-BSI, vancomycin can be a suitable choice for empirical treatment. In the current study, MRSA which caused community and hospital-acquired bloodstream infections was reported as 16.7% and 46.2%, respectively. However, the reported prevalence of MRSA was 79% in a study (five-year evaluation) conducted by Pourakbari et al. in Iran within 2001-2005. This prevalence was very higher than the value obtained in the current study; moreover, the mentioned study was performed on the patients who suffered from BSI (22).
As mentioned earlier, the antimicrobial pattern of BSI caused by gram-negative isolates in community-acquired infections was consistent with the hospital-acquired one. The best choice for antibiotic therapy was Imipenem or Meropenem, whereas ceftriaxone seemed to be ineffective. In Gram-positive cocci, the most resistance was observed to clindamycin and erythromycin and the most susceptibility was detected to vancomycin. In a study carried out in Nepal within 2006-2008 on neonatal sepsis, the most frequent organisms isolated from blood culture samples were Klebsiella, followed by S. aurous. Moreover, the most effective antibiotic against Gram-negative organisms was cefoperazone/sulbactam and vancomycin in Gram-positive bacteria (23). As illustrated by the obtained results, a number of factors have increased the resistance against antimicrobial drugs. They include adequate staff, state health laws, hygiene in medical processes, control measures, stringent hospital policy regarding diagnosis and treatment of hospital-acquired infections, ongoing training and education, limited medical methods and medical device use, proper application of disinfectants-washers, and antimicrobial medicines (24). Geographic variations in the prevalence of pathogens and profiles of antibiotic susceptibility necessitate continuous monitoring and lead to the selection of best therapeutic options (25).
Taking everything into account, the present study pointed to the high resistance of Gram-negative isolates against Cotrimoxazole and ceftriaxone, as well as clindamycin in Gram-positive isolates. Consequently, it can be used as a good guide for describing the empirical treatment in CA and HA infections. Moreover, the results suggested that Cefepime can be a promising choice for empirical treatment in UTI cases. Furthermore, a combination of gentamycin and vancomycin can be used as an empirical regime in hospital-sepsis.

 

Conclusion

In addition, the findings of the current study were indicative of the high resistance to several antibiotics that can be used as excellent choices in the treatment of both CA and HA-infections. On a final note, it is recommended that region-specific monitoring studies be carried out in order to assist the clinician to select the accurate empirical therapy.

Acknowledgements

The authors thank all those who helped them writing this paper.

Conflicts of Interest

Authors declared no conflict of interests.