Characteristics of hospital- and community-acquired meticillin-resistant Staphylococcus aureus in Tehran, Iran

Effect of MA01 rhamnolipid on cell viability and expression of quorum-sensing (QS) genes involved in biofilm formation by methicillin-resistant Staphylococcus aureus

A group of biosurfactants, called rhamnolipids, have been shown to have antibacterial and antibiofilm activity against multidrug-resistant bacteria. Here, we examined the effect of rhamnolipid biosurfactants extracted from Pseudomonas aeruginosa MA01 on cell growth/viability, biofilm formation, and membrane permeability of methicillin-resistant Staphylococcus aureus (MRSA) ATCC6538 bacterial cells. The results obtained from flow cytometry analysis showed that by increasing the concentration of rhamnolipid from 30 to 120 mg/mL, the cell viability decreased by about 70%, and the cell membrane permeability increased by approximately 20%. In fact, increasing rhamnolipid concentration was directly related to cell membrane permeability and inversely related to cell survival. Microtiter plate biofilm assay and laser scanning confocal microscopy analysis revealed that rhamnolipid, at a concentration of 60 mg/mL, exerts a reducing effect on the biofilm formation of Staphylococcus aureus. Real-time PCR analysis for monitoring the relative changes in the expression of agrA, agrC, icaA, and icaD genes involved in biofilm formation and related to the quorum-sensing pathway after treatment with rhamnolipid indicated a reduced expression level of these genes, as well as sortase A gene. The results of the present study deepen our knowledge regarding the use of microbial natural products as promising candidates for therapeutic applications.

Emergence of Methicillin-Resistant Staphylococcus aureus ST239/241 SCCmec-III Mercury in Eastern Algeria

In this paper, we investigate the epidemiology of infections-associated Staphylococcusaureus (S. aureus) from the Medical Intensive Care Unit (MICU) at University Hospital Center of Constantine (UHCC) in Algeria, with a special emphasis on methicillin-resistant strains (MRSA) revealed by cefoxitin disks (30 μg), then confirmed by penicillin-binding protein (PBP2a) agglutination and real-time polymerase chain reaction (RT-PCR) targeting mecA and mecC genes. Staphylococcal Cassette Chromosome mec (SCCmec type), staphylococcal protein A (spa-type), multilocus sequence type (MLST), Panton-Valentine Leucocidin (PVL), and toxic shock syndrome toxin-1 (TSST-1) were further investigated in all isolates, and whole genome sequencing was performed for a selected subset of three hospital-acquired MRSA (HA-MRSA) isolates. A measurement of 80% out of the 50 S. aureus isolates were identified as HA-MRSA harbouring the mecA gene, and 72.5% of them were multidrug resistant (MDR). Twelve STs, four different SCCmec cassettes, fourteen spa types, ten isolates Panton-Valentine Leukocidin (PVL)-positive, and three isolates TSST-1 were identified. Interestingly, there was a high prevalence (n = 29; 72.5%) of a worrisome emerging clone: the HA-MRSA ST239/241 SCCmec-III mercury with PVL negative, resistant to β-lactams, aminoglycosides, quinolones, and tetracyclines. Other clones of HA-MRSA isolates were also identified, including PVL-positive ST80 SCCmec-IV/SCCmec-unknown (22.5%), ST34 SCCmec-V with TSST-1 positive (2.5%), and PVL-negative ST72 SCCmec-II (2.5%). Genome analysis enables us to describe the first detection of both PVL-negative HA-MRSA ST239/241 SCCmec-III mercury carrying ccrC, as well as SCCmec-V cassette, which dramatically changes the epidemiology of S. aureus infections in one of the hospitals in eastern Algeria.

Genetic diversity of healthcare-associated methicillin-resistant Staphylococcus aureus isolates from Southern Iran

Staphylococcus aureus is a common pathogen causing hospital infections. The increasing rate of healthcare-associated infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in developing countries has led to many public health problems. This study aimed to investigate the molecular epidemiology as well as the antibiotic resistance pattern of clinical isolates of MRSA from Southern Iran. A total of 135 S. aureus isolates were collected from the patients referred to three hospitals in South Iran. The phenotypic and genotypic diagnosis of MRSA isolates was performed by disk diffusion and PCR methods, respectively. The antibiotic resistance pattern for MRSA isolates was performed using Kirby-Bauer method. The molecular epidemiology of isolates was performed by MLST, Spa typing and SCCmec typing. From 135 S. aureus isolates, 50 (37%) MRSA strains were detected from which two different sequence types including ST239 and ST605 were identified. SCCmec type III was the most common profile (50%) and t030 was the predominant spa type (48%) among the strains. The MRSA isolates had the highest resistance to penicillin (100%), tetracycline (88%), levofloxacin (86%), ciprofloxacin (84%), erythromycin (82%), gentamicin (80%), and clindamycin (78%). The results of this study show that the most common genetic type among the MRSA isolates was ST239-SCCmec III/t030. The rapid and timely detection of MRSA and the administration of appropriate antibiotics according to the published antibiotic resistance patterns are essential. Furthermore, the continuous and nationwide MRSA surveillance studies are necessary to investigate clonal distribution and spreading of MRSA from community to hospitals.

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.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus nasal carriage in the West of Iran: a population-based cross-sectional study

Background

Several reports designate the recent increase in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) nasal carriage. Because of the scanty information regarding the nasal carriage sate of MRSA in the west of Iran, the purpose of the present study was to determine the frequency of CA-MRSA in Sanandaj city.

Methods

Swabs collected from anterior nares of 600 volunteers were analyzed for the presence of S. aureus. The isolates were further investigated for methicillin resistance by using the cefoxitin disk diffusion test, followed by PCR-amplification of the mecA gene. SCCmec types and the presence of the Panton-Valentine Leukocidin (pvl) encoding genes were determined through PCR. Finally, the antimicrobial susceptibility of the isolates was determined by the agar diffusion method.

Results

Nasal screening identified 181 S. aureus, of which 55 isolates were MRSA. SCCmec types IV and V were detected in MRSA at frequencies of 80 and 20%, respectively. The overall frequency of pvl genes among the MRSA isolates was 14.54%. MRSA isolates were highly susceptible (98.18%) to mupirocin, gentamicin, and fusidic acid.

Conclusions

The high prevalence of CA-MRSA carriage in the population could pose a serious public health concern for the region. Additionally, advent of drug-resistant pvl-positive strains demands continuous surveillance on the colonization state of CA-MRSA in order to prevent dissemination of the bacterium in the community.

Genotyping and characterization of prophage patterns in clinical isolates of Staphylococcus aureus

Objective

Staphylococcus aureus is considered an important pathogen with a variety of virulence factors in communities and hospitals all around the world. Prophage typing is a practical technique for categorizing this bacterium. In this study, we focused on the detection of prophage patterns in methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains based on their virulence factors, antimicrobial resistance patterns, and molecular typing by rep-PCR.

Results

Out of 126 S. aureus isolates, 45 (35.7%) were identified as MRSA. In total, 17 different prophage types were detected and 112 strains out of 126 strains contained at least one prophage. There was a statistically significant relationship between hld, hlg, eta and SGA, SGA, and SGFb, respectively. The results of the rep-PCR analysis revealed 14 different patterns among the MRSA and MSSA isolates. In conclusion, the presence of different prophage-encoded virulence factors and antibiotic-resistant genes among MRSA strains enables them to produce a broad range of diseases. Thus, diverse MRSA strains which have these prophages can be considered as a potential threat to the patient’s health in either the hospital or the community.

Genetics of bi-component leukocidin and drug resistance in nasal and clinical Staphylococcus aureus in Lagos, Nigeria

BACKGROUND

Resistant and virulent Staphylococcus aureus is a global public health challenge. Staphylococcal Bi-component leukotoxins are cytolytic to immune cells and evolve to disarm the innate immunity during infections, hence the severity of the disease.

OBJECTIVE

We studied drug resistance profile and the occurrence of bi-component leukocidin in clinical and nasal S. aureus in Lagos, Nigeria.

METHOD

Ninety-two S. aureus (70 clinical and 22 nasal) strains were characterized by conventional and molecular methods.

RESULT

Of the resistance profiles generated, no isolate was resistant to fosfomycin, fusidic acid, teicoplanin, vancomycin, linezolid, mupirocin, nitrofurantoin and tigecycline. Twelve MRSA carrying staphylococcal cassette chromosome mecA gene types I, III, and IV elements were identified only in the clinical samples and type I dominated. High rates of lukE/D (100% among MRSA) and lukPV (dominated MSSA) were recorded among the nasal and clinical isolates. Staphylococcus aureus harboring only lukE/D (from clinical & colonizing MSSA) and combined lukE/D and lukPV (mostly from clinical MSSA, colonizing MSSA and clinical MRSA) toxins were found.

CONCLUSION

Although, mecA resistant genes were found only among clinical MRSA, the occurrence of other bi-component leukocidin genes in a large proportion among the isolates from both community and clinical settings is a major concern. The need for effective resistance and virulence factor surveillance, re-enforcement of antibiotic stewardship and good infection control policy, to prevent dissemination of epidemic strains is highlighted.

Typing of staphylococcal cassette chromosome mec encoding methicillin resistance in Staphylococcus aureus isolates in Ahvaz, Iran

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen. We sought to determine the frequency of the different types of SCCmec in MRSA isolates by performing a cross-sectional study. A total of 72 S. aureus isolates were collected from Imam Khomeini and Golestan hospitals and analysed for MRSA and SCCmec typing by multiplex PCR. The pattern of antibiotic resistance among S. aureus isolates was determined by disc diffusion analysis. Of the 72 S. aureus isolates, 29 (40.27%) were recognized as MRSA. SCCmec type III was the most common type, with 55.17% (16/29), followed by type II with 27.58% (8/29); type IV with 10.34% (3/29); and type I with 6.89% (2/29). All 29 MRSA isolates were resistant to chloramphenicol and erythromycin. In addition, resistance to cephalothin, gentamicin, clindamycin, ciprofloxacin, tetracycline and rifampicin was seen in 24 (75%), 26 (63.4%), 17 (94.4%), 27 (71.05%), 10 (71.42%) and 13 (68.42%) MRSA isolates, respectively. A decreased sensitivity of MRSA to the antibiotics used was observed, with type III SCCmec being the predominant isolate.

Antibiotic Resistance Patterns and Virulence Determinants of Different SCCmec and Pulsotypes of Staphylococcus Aureus Isolated from a Major Hospital in Ilam, Iran

Aims & Objectives:

The aim of this study is to evaluate genetic relatedness, antibiotic resistance pattern, and virulence characteristics of different types of S. aureus isolated from air, surfaces, staff, and patients in a Public hospital in Ilam.

Methods & Materials:

A total of 88 of 140 staphylococci identified as S. aureus by conventional and molecular methods were used in this study. Isolate samples were obtained from surfaces, staff, patients, and hospital indoor air. The sampling from staff and surfaces was done through using swab and air by standard pump. Antimicrobial susceptibility testing and presence different resistant and virulence determinants was assessed. Isolates were then typed by pulsed-field gel electrophoresis (PFGE) and SCCmec typing methods.

Results:

Out of 88isolates, 36 of them (40.9%) were MRSA. Among MRSA isolates, the range of resistance to antibiotic was 0% in vancomycin to 83.3% in gentamycin. The most prevalent resistant genes among gentamicin resistant S. aureus were acc (6')/aph (2”)Ia and aph(3”)IIIa. The most common erythromycin resistant gene was ermC. Surprisingly, SCCmec types I (30.5%), II (25%)were highly distributed. PFGE analysis showed 33 different pulsotypes.

Conclusion:

This study confirms that different isolates of MSSA and MRSA circulate in Ilam which differ in antimicrobial susceptibility, content of resistance, and virulence determinants.

Distribution of genes encoding resistance to aminoglycoside modifying enzymes in methicillin-resistant Staphylococcus aureus (MRSA) strains

Today Methicillin-Resistant Staphylococcus aureus (MRSA) have acquired multiple resistance to a wide range of antibiotics including aminoglycosides. So, this study was aimed to investigate the rate of aminoglycoside resistance and the frequency of aminoglycoside resistance mediated genes of aac(Ia)-2, aph(3)-IIIa and ant(4')-Ia among MRSA strains. A total of 467 staphylococci isolates were collected from various clinical samples. S. aureus strains were identified by standard culture and identification criteria and investigating of presence of 16S rRNA and nuc genes. Cefoxitin disk diffusion, and oxacillin-salt agar screening methods were used to detect the MRSA strains with subsequent molecular identification for the presence of mecA gene. Antibiotic susceptibility of MRSA strains against aminoglycoside antibiotics was evaluated by using agar disk diffusion method. Multiplex PCR for the presence of aac(Ia)-2, aph(3)-IIIa and ant(4')-Ia encoding genes for aminoglycosides were performed for MRSA strains. From total staphylococci tested isolates, 262 (56.1%) were identified as S. aureus, of which 161 (61.45%) were detected as MRSA and all comprised mecA gene. The resistance pattern of MRSA strains to aminoglycoside antibiotics were: gentamicin 136 (84.5%); amikacin 125 (77.6%); kanamycin 139 (86.3%); tobramycin 132 (82%); and neomycin 155 (96.3%). The frequency of aac(Ia)-2, aph(3)-IIIa, and ant(4')-Ia genes among MRSA strains, were 64%, 42% and 11.8% respectively. In conclusion, as MRSA strains are of great concern in human infections, the results of present study could provide a useful resource for health sectors for choosing appropriate antibiotics for the effective treatment of infections due to MRSA strains.

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.

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

Methicillin resistant Staphylococcus aureus is one of the most common causes of a variety of infections ranging from wound infections to urinary tract infections (UTI) in hospital and community. In this study during 3 years we characterized the antibiotic resistance patterns of 491 hospital acquired MRSA and community associated MRSA strains by the guidelines of clinical and laboratory standard institute. A combination of high resolution PhP typing method and SCCmec typing were used for clonal dissemination of isolates. Among all 491 MRSA strains, diverse PhP types consisting of 29 common types (CTs) and 4 single types (STs) and also 2 different SCCmec types (III and IVa) were detected. In addition, 18 CTs were common among CA- and HA-MRSA strains and the presence of all 4 STs was limited to HA-MRSA strains. All isolates were resistant to penicillin and high level resistance was observed against ciprofloxacin, erythromycin, tobramycin and kanamycin and the rate of resistance to most of the antibiotic tested among HA-MRSA was significantly higher than CA-MRSA isolates. Moreover, all isolates showed susceptibility to linezolid, vancomycin and quinupristin-dalfopristin and very low resistance to fusidic acid, nitrofurantoin and chloramphenicol were detected. Our findings illustrated the increasing rate of clonal dissemination and persistence of highly antibiotic resistant CA-MRSA strains in Tehran hospitals, and also indicated the important role of the hospitals as the reservoir of MRSA strains.

Characterization of Resistance to Aminoglycosides in Methicillin-Resistant Staphylococcus aureus Strains Isolated From a Tertiary Care Hospital in Tehran, Iran

Background:

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens which can cause a broad spectrum of infections.

Objectives:

The current study aimed to describe the frequency and antibiotic susceptibility patterns of clonal groups of gentamicin-resistant strains of MRSA isolated from a tertiary care hospital in Tehran, Iran.

Materials and Methods:

A total of 301 S. aureus isolates were collected during January to November 2012. All of the isolates were identified at the species level and typed using the Phene-Plate (PhP) system. The antibiotic susceptibility patterns of the MRSA strains and the presence of different aminoglycoside resistance genes were determined.

Results:

Of the 301 S. aureus isolates, 90 (29.9%) strains were confirmed as MRSA, and they showed high resistance to penicillin, ciprofloxacin, kanamycin, tobramycin, erythromycin, and tetracycline. On the other hand, 43 of the 90 strains (47.8%) were resistant to gentamicin. Aac (6’)-Ie + aph (2’’), ant (4’)-Ia, aph (3’)-IIIa, and ant (6)-Ia were detected in 65.6%, 42.2%, 20%, and 47.8% of the gentamicin-resistant strains, respectively. Diverse PhP types consisting of seven common types and four single types were identified among the strains.

Conclusions:

Our results illustrated the presence of clonal groups of highly gentamicin-resistant strains of MRSA in hospitals in Tehran. The PhP typing method provided useful information for both clonal dissemination and determining the epidemiological links of the clonal groups of the MRSA strains.

Biochemical Fingerprinting of Methicillin-Resistant Staphylococcus aureus Isolated From Sewage and Hospital in Iran

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is known as a common pathogen in nosocomial and community-acquired infections. Sewage acts as an environmental reservoir and may have a significant role in development and dissemination of antibiotic resistance.

OBJECTIVES

This study was undertaken to determine the epidemiological relatedness between the MRSA isolated from sewage and human infections.

MATERIALS AND METHODS

Samples were collected from a referral hospital and also a sewage treatment plant in Tehran, Iran, during 2010. All the MRSA isolates were identified at the species level and typed using Phene plate (PhP) system and SCCmec typing. Antibiotic susceptibility tests were also performed.

RESULTS

Of the 1142 isolates, 200 MRSA strains from the sewage (n = 100) and the clinic (n = 100) were isolated. Distinct PhP types, consisting of 16 common types and 13 single types, and also 3 different staphylococcal cassette chromosome mec (SCCmec) types (III, IVa and IVc) were found amongst the MRSA isolated from the two different sources. The results of antibiotic susceptibility testing showed an increased resistance to penicillin, ciprofloxacin, erythromycin, clindamycin and tetracycline. In addition, none of the isolates showed resistance to vancomycin, quinupristin -dalfopristin and linezolid.

CONCLUSIONS

The presence of common PhP types and also SCCmec type III, as an indicator for hospital strains, among the isolates, may indicate an epidemiological link between clinical and sewage MRSA isolates in Tehran.