Characterization of methicillin resistant Staphylococcus aureus strains among inpatients and outpatients in a referral hospital in Tehran, Iran

Epidemiological profile and antimicrobial resistance trends of Staphylococcus aureus in Chinese pediatric intensive care units from 2016 to 2022: a multi-center retrospective study

OBJECTIVE

This study aimed to analyze the profiles and evolution of Staphylococcus aureus in the pediatric intensive care units (PICUs) of 17 hospitals in China from 2016 to 2022.

METHODS

Susceptibility testing was performed to bacterial strains with a uniform monitoring protocol, which was provided by the US Clinical and Laboratory Standards Institute (CLSI) and used by the China Antimicrobial Surveillance Network (CHINET). The results were interpreted in accordance with the performance standards for antimicrobial susceptibility testing issued by the US Clinical and Laboratory Standards Institute.

RESULTS

Twenty-six thousand six hundred thirteen bacterial strains were isolated from 17 PICUs in China from 2016 to 2022, 3,147 of which were Staphylococcus aureus, ranking second among etiological agents of infections from PICUs. In 2022, Staphylococcus aureus had the highest detection rate, being 36.19%. And in 2021, MRSA had the highest detection rate, being 10.35% in Staphylococcus aureus. There were statistically significant differences in the annual detection rate of gram-positive bacteria, Staphylococcus aureus and MRSA between the years from 2016 to 2022 (P < 0.05). More males were found with Staphylococcus aureus or methicillin-resistant Staphylococcus aureus, but there were no statistical differences in gender distribution between any two years (P < 0.05). The top 3 highest detection rate of Staphylococcus aureus in age groups were infants (1244, 39.7%), toddlers (741, 23.7%), and children at school age and older (731, 23.4%). For MRSA, The top 3 in age groups were infants (91, 38.9%), children at school age and older (87, 29.1%), and toddlers (48, 20.5%). The detection rate of Staphylococcus aureus was statistically different in the distribution of age stratification (P < 0.05). There was no statistically significant difference in these two aspects of MRSA (P > 0.05). The top 3 highest detection rate of Staphylococcus aureus in infected sites were the lower respiratory tract (2,552, 81.7%), bloodstream (217, 6.5%), and skin wounds (110, 3.9%). For MRSA, The top 3 in infected sites were the lower respiratory tract (156, 77.9%), skin wounds (47, 8.8%), and bloodstream (15, 6.6%). The detection rate of Staphylococcus aureus and MRSA was statistically different in the distribution of infected sites (P < 0.05). All the strains of Staphylococcus aureus were sensitive to tigecycline, nitrofurantoin, vancomycin, and linezolid. The resistant rate of Staphylococcus aureus, to penicillin G was as high as 87.5% at least, to erythromycin was as high as 51.8% at least, to benzocillin was as high as 38.0% at least, to cefoxitin was as high as 35.5% at least, and to clindamycin was as high as 32.7% at least. All the strains of MRSA were sensitive to vancomycin, linezolid, quinupristin/dalfopristin, and tigecycline. Of these 234 strains of MRSA, 179 (76.5%) were resistant to erythromycin, 116 (49.6%) to clindamycin, 39 (16.7%) to tetracycline, 29 (12.4%) to levofloxacin, 27 (11.5%) to ciprofloxacin, 27 (11.5%) to moxifloxacin, 14 (6.0%) to TMP-SMX, eight (3.4%) to rifampicin, and six (2.6%) to gentamicin.

CONCLUSIONS

Staphylococcus aureus is the most common gram-positive bacterium in PICUs. Infants are most likely to be infected by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. And the lower respiratory tract is the most common infected site of Staphylococcus aureus. Staphylococcus aureus has a high resistant rates to commonly used antimicriobials in pediatrics, but no strains resistant to vancomycin and/or linezolid were found. When considering Staphylococcus aureus infection clinically, it is necessary to select antimicrobials reasonably based on the patient's age, infected site and local epidemiological characteristics.

Antimicrobial resistance profile of methicillin-resistant Staphylococcus aureus isolates in children reported from the ISPED surveillance of bacterial resistance, 2016-2021

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious threat to public health worldwide. In December 2015, the Infectious Disease Surveillance of Pediatrics (ISPED) program was organized to monitor bacterial epidemiology and resistance trends in children.

Methods

This retrospective study was conducted from January 2016-December 2021 on patients at eleven ISPED-group hospitals.

Results

From 2016-2021, a total of 13024 MRSA isolates were obtained from children. The most common age group for patients with MRSA infection was less than 3 years old, and newborns were an important group affected by MRSA infection. MRSA was most commonly isolated from the lower respiratory, an abscess, a secretion, or blood in neonates and from the lower respiratory, an abscess, or the upper respiratory in non-neonates. All isolates were susceptible to vancomycin and linezolid and resistant to penicillin; additionally, 76.88%, 54.97%, 22.30%, 5.67%, 5.14%, 3.63%, and 1.42% were resistant to erythromycin, clindamycin, tetracycline, levofloxacin, sulfamethoxazole-trimethoprim (TMP-SMX), gentamicin, and rifampin, respectively. Between 2016 and 2021, a significant increase was seen in the levofloxacin- and TMP-SMX-resistance rates (from 5.45% to 7.14% and from 4.67% to 6.50%, respectively) among MRSA isolates, along with a significant decrease in the rates of resistance to erythromycin (from 82.61% to 68.08%), clindamycin (from 60.95% to 46.82%), tetracycline (from 25.37% to 17.13%), gentamicin (from 4.53% to 2.82%), and rifampin (from 1.89% to 0.41%).

Discussion

The antibiotic-resistance rates varied among MRSA isolated from different sources. Because of the high antibiotic resistance rate to clindamycin, this antibiotic is not recommended for empirical treatment of MRSA infections, especially in osteomyelitis.

The global prevalence of fusidic acid resistance in clinical isolates of Staphylococcus aureus: a systematic review and meta-analysis

BACKGROUND AND AIM

Staphylococcus aureus (S. aureus) is one of the most common pathogens causing nosocomial and community-acquired infections with high morbidity and mortality rates. Fusidic acid has been increasingly used for the treatment of infections due to methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The present study aimed to determine the precise prevalence of fusidic acid resistant MRSA (FRMRSA), fusidic acid resistant MSSA (FRMSSA), and total fusidic acid resistant S. aureus (FRSA) on a global scale.

METHODS

Several international databases including Medline, Embase, and the Web of Sciences were searched (2000-2020) to discern studies addressing the prevalence of FRSA, FRMRSA, and FRMSSA. STATA (version14) software was used to interpret the data.

RESULTS

Of the 1446 records identified from the databases, 215 studies fulfilled the eligibility criteria for the detection of FRSA (208 studies), FRMRSA (143 studies), and FRMSSA (71 studies). The analyses manifested that the global prevalence of FRSA, FRMRSA, and FRMSSA was 0.5%, 2.6% and 6.7%, respectively.

CONCLUSION

This meta-analysis describes an increasing incidence of FRSA, FRMSSA, and FRMRSA. These results indicate the need for prudent prescription of fusidic acid to stop or diminish the incidence of fusidic acid resistance as well as the development of strategies for monitoring the efficacy of fusidic acid use.

Characterization of methicillin-resistant Staphylococcus aureus strains in sewage treatment plants in Tehran, Iran

Multidrug-resistant Staphylococcus aureus strains have been commonly found in hospitals and communities causing wide ranges of infections among humans and animals. Typing of these strains is a key factor to reveal their clonal dissemination in different regions. We investigated the prevalence and dissemination of different clonal groups of S. aureus with resistance phenotype to multiple antibiotics in two sewage treatment plants (STPs) in Tehran, Iran over four sampling occasions. A total of 576 S. aureus were isolated from the inlet, sludge and outlet. Of these, 80 were identified as methicillin-resistant S. aureus (MRSA) and were further characterized using a combination of Phene Plate (PhP) typing, staphylococcal cassette chromosome mec (SCCmec), ccr types, prophage and antibiotic-resistant profiling. In all, eight common type (CT) and 13 single PhP type were identified in both STPs, with one major CT accounting for 38.8% of the MRSA strains. These strains belonged to three prophage patterns and five prophage types with SCCmec type III being the predominant type. Resistance to 11 out of the 17 antibiotics tested was significantly (P < 0.0059) higher among the MRSA isolates than methicillin-sensitive S. aureus (MSSA) strains. The persistence of the strains in samples collected from the outlet of both STPs was 31.9% for MRSA and 23.1% for MSSA. These data indicated that while the sewage treatment process, in general, is still useful for removing most MRSA populations, some strains with SCCmec type III may have a better ability to survive the STP process.

Characterization of SCCmec, spa types and Multi Drug Resistant of methicillin-resistant Staphylococcus aureus isolates among inpatients and outpatients in a referral hospital in Shiraz, Iran

Objectives

Molecular typing such as spa typing is used to control and prevent Staphylococcus aureus widespread in hospitals and communities. Hence, the aim of this study was to find the most common types of S. aureus strain circulating in Shiraz via spa and SCCmec typing methods.

Results

Total of 159 S. aureus isolates were collected from two tertiary hospitals in Shiraz. Isolates were identified by biochemical tests. Antimicrobial susceptibility tests were performed by standard disk diffusion method and then genetic analysis of bacteria was performed using SCCmec and spa typing. In this study 31.4% of the isolates were methicillin-resistant S. aureus. The majority of isolates were SSCmec type III. Spa type t030 was the most prominent type among MRSA strains. For the first time in Iran, spa003, t386, t1877, t314, t186, t1816, t304, t325, t345 were reported in this study. It was shown that there is a possibility that these spa types are native to this region. Our findings showed that SCCmec II, III and IV disseminate from hospital to community and vice versa. Thus, effective monitoring of MRSA in hospital and community is necessary.

Biofilm production among methicillin resistant Staphylococcus aureus strains isolated from catheterized patients with urinary tract infection

Between June 2011 and May 2014, we isolated a total of 419 Staphylococcus aureus strains from catheterized patients with UTI in a referral hospital in Tehran. Of these, 108 were identified as methicillin resistant (MRSA) based on their phenotypic resistance to oxacillin and the presence of mecA gene. The MRSA isolates were tested for their clonality using a combination of PFGE, prophage typing, SCCmec and ccr typing and examined for their biofilm formation as well as their resistance against 17 antibiotics. In all, 15 common pulsotypes consisted of 105 isolates and 3 single types were identified among the MRSA strains of which, 97% carried SCCmec type III and type 3 ccr. Eighty three (77%) strains were positive for biofilm formation and also carried icaA and icaD genes. Moreover, agr group III and its related tst gene were detected in 81% and 77% of biofilm producing strains, respectively 105 of the 108 MRSA were multidrug resistant with 82.4% being resistant to more than 10 antibiotics. Strains with SCCmec type IV and type 2 ccr, contained SGA and SGL prophage types, were positive for pvl gene and belonged to single PFGE types. This study highlights the important role of biofilm formation and virulence factors of MRSA strains in catheterized patients.