National Update on Healthcare-Associated Infections in Iran for 2023—Based on the Iranian Nosocomial Infections Surveillance (INIS) System

Abstract

Background

Healthcare-associated infections (HCAIs) pose a serious threat to healthcare systems. Accurately determining the incidence of HCAIs is crucial for planning and implementing efficient interventions, as they are associated with a wide range of challenges. The objective of this study was to assess and update the incidence rates of HCAIs in Iran in 2023, using data from the Iranian Nosocomial Infection Surveillance (INIS) system, a nationwide hospital-based surveillance program.

Methods

The Iranian Center for Communicable Diseases Control (ICDC) evaluated data from 1,066 hospitals using the INIS software. Hospitals’ trained infection control staff collected all information and entered it into the INIS. HCAIs were diagnosed based on the CDC/NHSN case definition criteria. We calculated incidence rate (per 100 admissions and per 1,000 patient-days).

Results

We reported 170,948 HCAIs among 11,043,373 hospitalized patients, with an incidence rate of 4.95 per 1,000 patient-days, and the crude mortality rate of 19.85%. Looking at the relative frequencies, Pneumonia was the most frequent infection (28.32%), followed by urinary tract infections (UTIs) (26.6%), and surgical site infections (SSIs) (21.85%). HCAI rates were highest in intensive care units (ICUs), transplant wards, and burn units, with major surgeries like cardiovascular, neurosurgeries, and orthopedics having the highest SSI rates. The most common microorganisms were Klebsiella spp. (16.56%) and E. coli (14.6%), with high proportions of multidrug-resistance (MDR) including MRSA (43.2%), VRE (65.24%), and KPC (74.21%).

Conclusions

This study reveals a high incidence of HCAIs in Iranian hospitals in 2023, with pneumonia, UTIs, and SSIs being most common. The high proportion of MDR pathogens underscores the need for enhanced infection control, antibiotic stewardship program, and continuous staff education to reduce HCAIs and improve patient outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s44197-025-00462-2.

Background

Healthcare-associated infections (HCAIs) are defined by the Centers for Disease Control and Prevention (CDC) as infections acquired in a healthcare setting that manifest either within 48 h of hospitalization or within three days after discharge [1, 2]. HCAIs significantly impact patients and healthcare systems, contributing to prolonged hospital stays, increased complications, and elevated mortality rates [3]. Healthcare systems impose a considerable economic burden from HCAI infections, which often require more intensive care, additional treatments, patient isolation, and potential readmission. Effective prevention relies on stringent infection control measures, proper hand hygiene, and antibiotic stewardship programs [4].

According to data from the U.S. CDC, before the COVID-19 pandemic, approximately 1.7 million hospitalized individuals in the United States acquired an HCAI each year, and one in 17 affected patients died as a result [5, 6].

According to previous studies, the endemic prevalence of HCAIs in general wards is around 15.5%, while in intensive care units (ICUs) in African nations, it can reach up to 50% [7–10]. Additionally, a Canadian study from 2017 reported that 7.9% of hospitalized patients acquired at least one HCAI during their stay. Furthermore, the European Centre for Disease Prevention and Control estimated a point prevalence of 7.1% for HCAIs in tertiary care hospitals across Europe [11].

The Infectious Disease Control Center (ICDC) in Iran developed the Iranian Nosocomial Infection Surveillance (INIS) software system to facilitate the documentation and monitoring of HCAIs. In 2018, the system recorded an overall hospital infection rate of 1.33%, which was higher than the reported rate in 2017. Notably, the incidence of infections varied significantly across healthcare facilities, ranging from 0.01 to 33.45%. Pneumonia (29.1%), urinary tract infections (UTIs) (25.6%), surgical site infections (SSIs) (21.8%), and bloodstream infections (BSIs) (11.6%) were among the most common HCAIs [12].

According to estimates from the World Health Organization (WHO), in 2019, approximately 100 million people worldwide were affected by HCAIs each year [6]. Because HCAIs are complicated, understanding their frequency and underlying causes is essential for effective planning, prevention, and control efforts [1]. Healthcare professionals, researchers, and policymakers are increasingly seeking up-to-date national data to create efficient infection prevention and control (IPC) strategies due to discrepancies in reported numbers and the recent rise in hospital infections. Accordingly, the present study was conducted to update the data on the incidence rates of HCAIs nationwide in Iran in 2023— using the INIS system.

Methods

Study Overview

All data were recorded under the supervision of the Ministry of Health and Medical Education of Iran and approved by the ICDC Research Council (ICDC, 2024). Data were extracted using the Iranian Hospital Infection Surveillance Software (INIS), which has been used since 2007 (INIS, 2023), with its latest update in 2017 [12]. The system currently includes data from 1,066 hospitals up to the end of 2023 (INIS, 2023). Information is updated monthly by a trained infection control nurse, and data entry follows the criteria based on the occurrence of any healthcare-associated infections (ICDC, 2024).

Data Collection Process

Data, including demographic characteristics (such as age, gender, department, admission and discharge dates), diagnoses, device information, and microbiological studies, were collected using standard checklists and entered into the INIS system.

Diagnostic Criteria and Definitions

The diagnostic criteria for HCAIs were based on the CDC/NHSN case definitions [13], as adopted by the ICDC guidelines [12] (Supplementary File).

Statistical Analysis

The analysis focused on HCAIs and mortality rates. The ICDC conducted the final analysis of all retrieved forms. Key items of interest, such as the number of hospitalizations, HCAI diagnoses, and mortality rates, were extracted and analyzed.

Definition of Epidemiological Terms

Incidence Rate

The number of new HCAI cases per 1,000 patient-days. This rate accounts for the time each patient was at risk and provides a time-adjusted measure of occurrence.

Prevalence

This term was used specifically about the distribution of microbial pathogens isolated from different infection sites. It does not refer to disease burden or point/period prevalence of infections, and its usage is limited to microorganism frequency analysis in Tables 1 and 2.

Table 1.

Distribution of microorganisms by infection type in HCAIs—Iran, 2023

Microorganisms	SSI (%)	BSI (%)	UTI (%)	PNEU (%)	Other infection (%)	Total (N)	Frequency (%)
Staphylococcus aureus	7.2	10.7	1.8	3.8	4.8	8444	4.9
Staphylococcus epidermidis	1	16.3	0	0	1.6	4051	2.36
Enterococcus 1	2.7	6.4	6.8	0	1.8	5735	3.35
Streptococci 2	0.4	0.7	0.4	0.5	0.3	771	0.45
Acinetobacter	4	9.9	2.1	22.2	5.8	16,384	9.58
Pseudomonas aeruginosa	3.7	9.1	7.9	9.6	6.2	12,659	7.4
Stenotrophomonas maltophilia	0.1	2.5	0.1	0.5	0.2	883	0.51
Klebsiella	8	17.4	16.1	27.1	6.8	28,319	16.56
E. coli	8.3	10.5	36.4	4.7	0.4	24,942	14.6
Other Enterobacteriaceae 3	4.3	7.3	5.3	7.9	4.2	10,197	5.96
Candida 4	0.7	2.5	10.6	0	0.5	5695	3.33
Other microorganisms	59.6	6.7	12.5	23.7	63.4	52,868	31
Total	100	100	100	100	100	170,948	100

1. Among Enterococcus isolates, E. faecium accounted for 51.6%, while E. faecalis represented 48.4%

2. Streptococci include Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae

3. Other Enterobacteriaceae encompass Enterobacter spp., Proteus spp., Serratia spp., and Citrobacter spp

4. Candida albicans constituted 67%, with non-Candida albicans species making up 33%

HCAIs: Healthcare-Associated Infections; PNEU: Pneumonia; UTI: Urinary Tract Infection; BSI: Bloodstream Infection; SSI: Surgical Site Infection

Table 2.

Antibiotic resistance profiles of common microorganisms isolated from HCAIs—Iran, 2023

Microorganisms	Antibiotics	Resistance rate (%)	Interpretation
Staphylococcus aureus	Oxacillin or cefoxitin	44.32	MRSA
	Clindamycin	71.49	-
	Vancomycin	0.1	-
Enterococcus spp.	Ampicillin	65.75	-
	Vancomycin	65.24	VRE
	Linezolid	0.68	-
Klebsiella pneumonia	3rd. or 4th. generation cephalosporins	86.9	ESBL
	Fluoroquinolone	81.12	-
	Beta-lactamase inhibitors	85.44	-
	Carbapenem	74.21	KPC
	Colistin	1.06	-
Escherichia coli	3rd or 4th generation cephalosporins	71.22	ESBL
	Fluoroquinolone	65.97	-
	Beta-lactamase inhibitors	51.38	-
	Carbapenem	25.06	-
Pseudomonas aeruginosa	Ceftazidime	65.48	-
	Fluoroquinolone	67.63	-
	Aminoglycoside	65.95	-
	Piperacillin Tazobactam	62.03	-
	Carbapenem	73.67	-
Acinetobacter baumannii	Ceftazidime	93.57	-
	Fluoroquinolone	92.04	-
	Aminoglycoside	86.71	-
	Ampicillin Sulbactam	82.25	-
	Carbapenem	94.31	-
	Colistin	4.17	-

MRSA: methicillin-resistant Staphylococcus aureus; VRE: vancomycin-resistant Enterococcus; ESBL: Extended-spectrum beta-lactamase; KPC; Klebsiella pneumoniae carbapenemase

Results

Table 3 provides a comprehensive overview of the distribution of HCAI types and the associated incidence and mortality rates.

Table 3.

Distribution and epidemiological rates of HCAIs by infection Type—Iran, 2023

	Denominator (Total hospital admissions)	Total HCAIs	SSI	BSI	UTI	PNEU	Other
Number of infected participants (frequency)	11,043,373	170,948	37,355	20,576	45,463	48,418	19,136
Relative frequency (%) (Percentage of each infection type among all HCAIs)	170,948 1	100	21.85	12.03	26.6	28.32	11.2
Incidence (%) (Per 100 hospital admissions) *	11,043,373 2	1.54	0.34	0.18	0.41	0.44	0.17
Incidence rate (%) (Per 1000 patient-days) *	34,488,608 3	4.95	1.08	0.6	1.32	1.41	0.55
Mortality rate (%) (Deaths per 100 infected patients)	171,370 4	19.85	1	3.13	3.90	10.57	1.25

HCAIs: Healthcare-Associated Infections; PNEU: Pneumonia; UTI: Urinary Tract Infection; BSI: Bloodstream Infection; SSI: Surgical Site Infection

¹ The proportion of each infection type among total HCAIs: 170,948

2 Total hospital admissions: 11,043,373

3 Total patient-days: 34,488,608

4 Total deaths refer to deaths among all hospitalized patients (not just HCAI cases) per 100 infected patients: 171,370

*The incidence per 100 admissions represents the proportion of infected patients per hospitalization event, reflecting overall infection risk. The per 1,000 patient-days rate accounts for exposure duration for hospital stay, measuring infection density over time, particularly important for units with prolonged stays like ICUs

The study calculated the incidence of HCAIs over 12 months in 2023 based on INIS data. A total of 1,066 hospitals nationwide were examined. Among 11,043,373 admissions, 170,948 patients were identified with at least one HCAI. Of these patients, 57.1% were male. Crude mortality among HCAI patients was 19.85% overall. The incidence of hospital infections was reported at 1.54%, with an incidence rate of 4.95 per 1,000 patient-days.

Additionally, a detailed analysis by hospital ward showed that the internal ICU had the highest incidence rate of HCAI (12.96%), followed by the general ICU (10.57%), transplantation units (9.23%), burn wards (7.92%), and surgical ICU (7.08%). The internal ICU had the highest mortality rates (48.43%), followed by the general ICU (40.24%) and the surgical ICU (38.54%). On the other hand, wards like pediatrics, ENT, OB-GYN, psychiatry, and ophthalmology had the lowest incidence and mortality rates. More The correlation between high incidence and mortality indicates the sinister need for effective infection prevention measures in intensive and high-dependency care settings. Figures 1 and 2 provide a comparative visualization of the incidence and mortality of HCAI across wards.

Fig. 1.

Incidence Rates of HCAIs by Hospital Ward in Iran, 2023

Fig. 2.

Mortality Rates of HCAIs by Hospital Ward in Iran, 2023

In the following, pneumonia was not only the most frequent HCAI (28.32%) but also the leading cause of death among HCAI patients, with 1,057 deaths per 1000 cases. UTIs and BSIs followed in frequency—accounting for 26.6% and 12.03% of all HCAIs, respectively—and were also associated with substantial mortality rates of 390 and 313 deaths per 1000 patients.

Table 1 classifies HCAIs based on the type of microorganisms and infections. Data reveal that Klebsiella spp. and Staphylococcus epidermidis are the most common microorganisms responsible for BSIs. Additionally, E. coli and Klebsiella spp. are the primary microorganisms associated with UTIs. Strains of Klebsiella and Acinetobacter play a significant role in pneumonia cases, while other microorganisms have a notable impact on SSIs.

Table 2 shows that the prevalence of ESBL-producing strains was notably high, particularly among Klebsiella pneumoniae (86.9%) and E. coli (71.22%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) were approximately 44.32% and 65.24%, respectively. Pseudomonas aeruginosa, known for its high resistance, exhibited the highest resistance to carbapenems (73.67%), while Acinetobacter spp. also showed significant resistance in this category (94.31%). The prevalence of Klebsiella pneumoniae carbapenem (KPC) were approximately 74.21%. Furthermore, gram-negative bacilli producing beta-lactamase were reported at a rate of 71.22%.

Various surgical specialties had varying rates of SSIs. The highest SSI rates were observed in vascular surgery (1.44%) and neurosurgery (1.41%), followed by orthopedic surgery (1.03%) and cardiac surgery (0.97%). Notable infection rates were also found in urological (0.73%), general (0.80%), and gynecological (0.83%) surgeries. Conversely, ophthalmic surgery (0.16%) and Ear, Nose, and Throat (ENT) surgery (0.29%) had the lowest rates of SSI.

Device-associated infection (DAI) rates further emphasize this trend: ventilator-associated pneumonia (VAP) occurred at a markedly high rate of 22.74 cases per 1,000 ventilator connections per day. Similarly, UTIs and BSIs occurred at 4.15 and 2.45 cases per 1,000 catheter or central line days, respectively.

Discussion

This national study has improved surveillance of HCAIs in Iran by providing up-to-date epidemiological insights through the INIS system. The findings reveal critical patterns in infection distribution and clinical outcomes in healthcare settings, increasing understanding of infection control practices and guiding future interventions.

Our findings indicate that the incidence of HCAIs across 1,066 hospitals nationwide was reported at 1.54%. Detailed analyses revealed that pneumonia had the highest incidence of hospital-acquired infections. Additionally, the mortality associated with HCAIs showed that pneumonia is the leading cause of death related to these infections. The study found that the incidence of infections related to healthcare was higher in ICU settings, burn units, and transplant services. Furthermore, surgical infections were most frequently reported following cardiovascular, neurosurgical, and orthopedic procedures. Our results broadly align with those of Raoofi et al. [14], who reported wound infections as the most common HCAIs, followed by bloodstream infections and surgical site infections, while also highlighting a considerable burden of pneumonia, particularly in ICUs, burn units, and organ transplant services. Compared with earlier studies, including one conducted in 2018, the overall incidence of HCAIs appears to have increased (1.54% versus 1.34%) [14, 15]. Moreover, Raoofi et al., in their study of 400 studies including 29,159,630 participants, reported a global HCAI prevalence of 0.14% with an annual increase of 0.06%, consistent with our findings [14, 16].

The epidemiological analysis of microorganisms causing HCAIs in this study revealed that many microorganisms were unidentified. Among those identified, Klebsiella spp., E. coli, Acinetobacter spp., and Pseudomonas aeruginosa were the most common pathogens responsible for hospital infections [14]. Further breakdown showed that Klebsiella spp. was a major cause of UTIs, pneumonia, and BSIs [14]. The MRSA prevalence rate was estimated to be approximately (18.5–49%) in various countries. In countries such as Japan, China, Taiwan, and Singapore, the infection rates caused by MRSA exceed 50% [17]. A recent study in Iran found a prevalence rate of 44.32%.

According to the National Healthcare Safety Network (NHSN), 35.5% of clinical strains were VREs, which is lower than the prevalence rate of 65.24% found in the current study in Iran [17]. The rate of ESBL-producing strains, especially among the Klebsiella pneumoniae, was 86.9%; higher than in North America and Europe, where the prevalence rates are 12.05% and 45.6%, respectively [17]. Anticipating the trajectory of antimicrobial resistance, especially in developing nations, poses significant challenges [17]. It is essential to raise awareness and implement comprehensive global, regional, and local strategies for infection control and surveillance to effectively curb the proliferation of MDR microorganisms [17]. It is imperative to promote judicious outpatient antibiotic prescriptions to mitigate risks to human, animal, and environmental health [17].

The 2019 Global Burden of Disease study noted a rise in UTI incidence from 4.7 to 5.2 per 100 individuals between 2009 and 2019 [18]. Zhu et al. reported UTI prevalence rates of 1.64% and 0.69 per 1,000 patient-days in immobile hospitalized patients, with catheter-associated UTIs at 2.25 per 1,000 catheter days [19]. Factors such as prolonged hospital stays, urinary catheters, female gender, and older age were identified as major risk factors for UTI and its complications [19].

Pneumonia is another common HCAI. The study found a pneumonia incidence rate of 0.44 per 100 individuals [14]. A cohort study conducted in France from 2013 to 2019 reported pneumonia incidences of 1.17%, 3.95%, and 1.91% for age groups 18–49, 50–64, and 65 and older, respectively [20]. A Portuguese study indicated a hospital-acquired pneumonia incidence of 0.95 per 100 individuals from 2014 to 2017, with affected individuals having longer hospital stays and higher mortality rates [21]. Kim et al. reported a 5% incidence of hospital-acquired pneumonia among 512,278 patients, identifying factors such as older age, male gender, pre-existing lung conditions, tube feeding, suction, mechanical ventilation, ICU admission, poverty, higher nurse-to-bed ratios, and more beds per room as contributors to increased pneumonia rates [22].

The study also noted that the incidence of SSI was 0.34 per 100 individuals, which is lower than previous findings. Gillespie et al. reported a 30-day SSI rate of 11%, significantly higher than in our study [23].

The incidence of BSIs was reported as 0.18 per 100 individuals, consistent with a Finnish population-based study reporting rates between 0.15 and 0.3 per 100 individuals [24]. Natalia et al. found that BSI incidence decreased with age, with Klebsiella pneumoniae (15.9%), Staphylococcus aureus (14.3%), E. coli (13.1%), and Acinetobacter spp. (12.1%) being the most common pathogens [25].

Various factors such as the need for ventilators, vascular access, catheterization, surgical complications, lapses in infection control practices, and inappropriate or excessive antibiotic use may contribute to the increased incidence of HCAIs over time [26–28].

Conclusion

This comprehensive study offers a detailed overview of healthcare-associated infections in Iran, serving as a valuable resource for healthcare authorities. To effectively address this issue, it is crucial to provide ongoing training for healthcare personnel and ensure the proper implementation of infection prevention measures. Special attention should be given to the correct use of ventilators and catheters, as well as regular updates to protocols to ensure accurate reporting of healthcare-associated infections. Additionally, future studies could explore the application of a multimodal approach and evaluate hospitals based on their adherence to effective intervention protocols.

Supplementary Information

Below is the link to the electronic supplementary material.

Author Contributions

M.Sh., A.S., and R.M.; Conceptualization, Data curation, Investigation, Methodology, Supervision, Validation, Witting- Orginal draft, Writing- review & editing, M.Z.; Data curation, Investigation, Methodology, Witting- Orginal draft, Writing- review & editing, K.K; Data curation, Investigation, Methodology, Witting- Orginal draft, Writing- review & editing, Sh.A.; Data curation, Investigation, Methodology, Witting- Orginal draft, Writing- review & editing, M.RF.; Data curation, Investigation, Methodology, Witting- Orginal draft, Writing- review & editing. All authors critically reviewed and approved the final version of the manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data Availability

No datasets were generated or analyzed during the current study.

Declarations

Ethical Approval

The ICDC Research Council approved this study, and all data were registered under the supervision of the Iranian Ministry of Health and Medical Education. This study was approved by the ethics committee of Tehran University of Medical Sciences, Tehran, Iran (No. IR.TUMS.SPH.REC.1404.057).

Consent for Publication

Informed consent was not required for this study.

Competing Interests

The authors declare no competing interests.