The Frequency of Methicillin-Resistant Staphylococcus aureus and Coagulase Gene Polymorphism in Egypt

Emerging Challenges in Staphylococcus aureus Bloodstream Infections: Insights from Coagulase Typing, Toxin Genes, and Antibiotic Resistance Patterns

Background

The incidence of complications and mortality associated with Staphylococcus aureus (S. aureus) bloodstream infections has been increasing significantly, particularly in developing countries where control strategies against this virulent pathogen and its resistance to antibacterial agents are insufficient. The aim of this study was to investigate coagulase typing, the prevalence of toxin genes, and the antibiotic resistance profile of S. aureus isolated from bloodstream infections.

Methods

Antibiotic susceptibility of the isolates was determined by the disk diffusion method. The prevalence of toxin genes was determined using the polymerase chain reaction (PCR) method. Genetic variability of isolates was determined using multiplex PCR based on coagulase gene polymorphism.

Results

Out of 120 strains, 55 (46%) were methicillin-resistant S. aureus (MRSA) and 65 (54%) were methicillin-sensitive S. aureus (MSSA). All isolates were susceptible to linezolid and teicoplanin but showed varying levels of resistance to other antibiotics. The highest resistance was observed for ampicillin (92.5%), gentamicin (69.2%), and amikacin (68.3%). Multidrug resistance was observed in all isolates. PCR analysis revealed a higher prevalence of toxin genes in MRSA (tst: 38%, pvl: 29.1%, eta: 10%, and etb: 4.1%) than that in MSSA. According to the coa typing, the most prevalent types were coa III (29.2%), coa II (26.7%), and coa VI (10%).

Conclusion

The presence of genetic variability and widespread multidrug resistance in our hospitals emphasizes the circulation of various coa types. Therefore, it is crucial to implement antimicrobial stewardship and infection control measures to prevent and control the spread of these strains.

Comparative Genotypic Analysis of RAPD and RFLP Markers for Molecular Variation Detection of Methicillin-Resistant Staphylococcus aureus Clinical Isolates

Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) isolates are associated with various diseases ranged from mild superficial impairments to invasive infections. This study aimed to evaluate the ability of polymerase chain reaction (PCR) based methods namely, restriction fragment length polymorphism (RFLP) of the coa gene and random amplified polymorphic DNA (RAPD), to determine the genetic diversity of MRSA isolates. Materials and Methods: A total of 37 MRSA isolates were conventionally identified depending on their biochemical and microbiological culture characteristics. Genotypic confirmation was based on detection of the associated mecA gene. The genetic variation amongst MRSA isolates was evaluated following the coa gene-based RFLP and RAPD fingerprints. Results: Results illustrated that, the species specific coa gene was detected in all MRSA isolates. The irregular bands intensity, number, and molecular sizes of the PCR amplicons demonstrated the coa gene polymorphism. The incompatible AluI digestion patterns of these amplicons classified the tested MRSA isolates into 20 RFLP patterns which confirm the coa gene polymorphism. Additionally, the PCR-based RAPD analysis showed variable bands number with size range of approximately 130 bp to 4 kbp, which indicated the genetic variation of the tested MRSA isolates as it created 36 variable RAPD banding profiles. Conclusions: coa gene AluI enzymatic restriction sites, amongst the tested MRSA isolates, certify their genetic variation on the basis of the accurate but complicated and relatively expensive coa gene-based RFLP. Conversely, the results verified the excellent ability of the simple and cost-effective PCR-based RAPD analysis to discriminate between MRSA isolates without any preface data about the genome.

Evaluation of aminoglycoside modifying enzymes, SCCmec, coagulase gene and PCR-RFLP coagulase gene typing of Staphylococcus aureus isolates from hospitals in Shiraz, southwest of Iran

Staphylococcus aureus is an important human pathogen that causes various infections. Aminoglycosides are broad-spectrum antibiotics used to treat methicillinresistant S. aureus (MRSA) infections. Typing of S. aureus isolates by coagulase gene typing and PCR-RFLP coa gene is a fast and suitable method for epidemiological studies. Aim of the present study was to evaluate the resistance to aminoglycosides, staphylococcal chromosomal cassette mec (SCCmec) types, coagulation typing and PCR-RFLP coa gene in clinical isolates of S. aureus. 192 S. aureus isolates were collected from Namazi and Shahid Faghihi hospitals. Antibiotic resistance was measured by disk diffusion method and MIC was determined for gentamicin. The presence of genes encoding aminoglycoside modifying enzymes (AME) and mecA gene were assessed by PCR. Also the coagulase typing, PCR-RFLP coa gene, and SCCmec typing were performed. Out of 192 isolated S. aureus isolates, 83 (43.2%) MRSA isolates were identified. In this study, a high resistance to streptomycin and gentamicin (98.7%) were observed. Among the AME genes, the aac (6′)-Ie-aph (2″) gene was the most common. Based on the SCCmec typing, it was determined that the prevalence of SCCmec type III (45.8%) was highest. From the amplification of the coa gene, 5 different types were obtained. Also, in digestion of coa gene products by HaeIII enzyme, 10 different RFLP patterns were observed. According to this study, aminoglycoside resistance is increasing among MRSA isolates. As a result, monitoring and control of aminoglycoside resistance can be effective in the treatment of MRSA isolates. Also, typing of S. aureus isolates based on coagulase gene polymorphism is a suitable method for epidemiological studies.

Study of antibiotics sensitivity pattern and molecular characterization of Staphylococcus aureus isolated from human and animal pyogenic cases

Staphylococcus aureus has been described as the most common cause of human and animal diseases and has emerged as a superbug due to multidrug resistance. Considering these, a total of 175 samples were collected from pyogenic cases of humans (75) and animals (100), to establish the drug resistance pattern and also for molecular characterization of human and animal isolates. Thermonuclease (nuc) gene amplification was used to confirm all presumptive S. aureus isolates and then, antibiotic sensitivity and slide Coagulase tests were used for phenotypic characterization of isolates. Following that, all the isolates were subjected to PCR amplification to detect the existence of the Methicillin-resistant (mecA) and Coagulase (coa) genes. Lastly, typing was done using the Randomly Amplified Polymorphic DNA-PCR. The overall prevalence of S. aureus in human and animal samples was found to be 39.4%. Drug sensitivity revealed the highest resistance against the β-lactam antibiotics such as ampicillin (94.8%) and penicillin (90.6%), followed by cephalosporin (cefixime-67.7%) and quinolone (ciprofloxacin-52.1%) group of drugs. The drug sensitivity was the highest against antibiotics like chloramphenicol (95%) followed by gentamicin (90%). Among the 69 S. aureus isolates, the overall presence of MRSA was 40.5% (27.5% and 50% in human and animal isolates, respectively). Total 33 isolates exhibited coa genes amplification of more than one amplicons and variable in size of 250, 450, 800, and 1100 bp. The RAPD typing revealed amplification of five and six different band patterns in humans and animals, respectively, with two common patterns suggesting a common phylogenetic profile.

Emergence of CC8/ST239- SCCmec III/t421 tigecycline resistant and CC/ST22-SCCmec IV/t790 vancomycin resistant Staphylococcus aureus strains isolated from wound: A two-year multi-center study in Tehran, Iran

Staphylococcus aureus as an opportunistic bacterial pathogen with intrinsic and acquired resistance to many antibiotics is a worldwide problem. The current study was undertaken to evaluate the resistance pattern, and determine the genetic types of multidrug-resistant S. aureus isolated from wound. This cross-sectional study was conducted over the period of two years (from December 2018 to November 2020) at the hospitals affiliated to Shahid Beheshti University of Medical Sciences, Tehran, Iran. In present study, 75 multidrug-resistant S. aureus isolates collected from wound infections were investigated. Phenotypic resistance was assessed by Kirby-Bauer disk diffusion method. Conventional PCR was performed for the detection of virulence encoding genes. Genotyping of strains was performed based on coa gene polymorphism using multiplex-PCR assay. SCCmec typing, spa typing and MLST were also used to characterize the genotype of the mupirocin, tigecycline and vancomycin resistant multidrug-resistant S. aureus isolates. All 75 multidrug-resistant S. aureus isolates in the study were confirmed as MRSA. Coagulase typing distinguished isolates into five genotypic patterns including III (40%), I (24%), IVb (16%), V (10.7%) and type X (9.3%). Resistance to tigecycline was detected in 4% of MDR-MRSA isolates and all belonged to CC8/ST239- SCCmec III/t421 lineage. According to our analysis, one VRSA strain was identified that belonged to coa type V and CC/ST22-SCCmec IV/t790 lineage. Resistance to mupirocin was detected in 9.3% of strains. All 7 mupirocin resistant MDR-MRSA isolates exhibited resistance to mupirocin in high level. Of these, 4 isolates belonged to CC/ST8-SCCmec IV/t008 (57.1%), 2 isolates belonged to CC/ST8-SCCmec IV/t064 (28.6%) and one isolate to CC/ST22-SCCmec IV/t790 (14.3%). Altogether, current survey provides a snapshot of the characteristics of S. aureus strains isolated from patients. Our observations highlighted type III as predominant coa type among multidrug-resistant MDR strains indicating low heterogeneity of these isolates. Our study also indicates the importance of continuous monitoring of the genotypes of MDR-MRSA isolates to prevent nosocomial outbreaks and the spread of MDR isolates.

What is behind phylogenetic analysis of hospital-, community- and livestock-associated methicillin-resistant Staphylococcus aureus?

Methicillin-resistant Staphylococcus aureus (MRSA) has been shown to be the predominant life-threatening pathogen in Egypt. MRSA is a major cause of severe healthcare-associated (HA) infections. During the last decades, the incidence of community-associated (CA) MRSA infections has a complex epidemiology arising from the circulation of different strains in the general population. Moreover, livestock-associated (LA) MRSA emerged recently becomes an emerging threat to public health. Therefore, it is important to illuminate the differences between CA-, HA- and LA-MRSA to shed light on their genetic diversity and evolution. This study presents the first data on analysing the correlation between CA-, LA- and HA-MRSA using antibiogram typing, molecular characteristics and antimicrobial resistance and virulence genes' profiles. Overall, HA-MRSA strains tended to be multidrug resistant and less virulent than both LA- and CA-MRSA strains. Importantly, CA-MRSA strains had a high homology with each of HA- and LA-MRSA. However, no similarity was observed between HA- and LA-MRSA. Our findings suggest that the epidemiological changes in genetic behaviour between HA- and LA-MRSA are due to the presence of CA-MRSA confirming that CA-MRSA has created a public health crisis worldwide.

Detection of coagulase gene in Staphylococcus aureus from several dairy farms in East Java, Indonesia, by polymerase chain reaction

Aim:

This study was conducted to study the coagulase (coa) gene-based genetic diversity of Staphylococcus aureus, isolated from different samples of cattle from three different regions in East Java Province, Indonesia.

Materials and Methods:

A total of 160 raw milk samples collected in East Java Province, Indonesia, were screened for the presence of S. aureus. The presumptive isolates were confirmed by coa test. The confirmed S. aureus isolates were subjected to coa gene polymerase chain reaction.

Results:

Of 160 different samples, 20 (12.5%) isolates of S. aureus were confirmed by positive coa test. Of 20 S. aureus isolates, 19 (95%) isolates carried coa gene. Six different genotypes of coa gene, i.e., 440 bp, 510 bp, 547 bp, 680 bp, 740 bp, and 820 bp were obtained. One coa genotypes, 510 bp (10 isolates) were observed in polymorphism to be more prevalent than the others, and the genotype was present in at least one isolates from every region.

Conclusion:

It can be concluded that coa gene is easily epidemiological tool for detection of variation strain from S. aureus.

Distribution of Aminoglycoside-Modifying Enzymes and Molecular Analysis of the Coagulase Gene in Clinical Isolates of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus

Enzymatic alteration of aminoglycosides by aminoglycoside-modifying enzymes (AMEs) is the major mechanism of resistance to aminoglycosides. The purpose of this study was to determine the frequency of AME genes, staphylococcal chromosomal cassette mec (SCCmec) types, and molecular analysis of the coagulase (coa) gene in Staphylococcus aureus strains isolated from clinical specimens. Totally, 102 S. aureus were tested by disk diffusion and microbroth dilution methods for susceptibility to aminoglycosides. AMEs genes and SCCmec types were determined by multiplex polymerase chain reaction (PCR). For polymorphism analysis, the 3' end region of the coa gene was amplified by PCR and the products were then subjected to restriction digestion with HaeIII enzyme. Of the 102 S. aureus, 42 (41.2%) were methicillin-resistant S. aureus (MRSA). Thirty-five (83%) of MRSA strains were resistant to kanamycin, 32 (76.2%) to tobramycin, 30 (71.4%) to gentamicin, 25 (59.5%) to amikacin, and 10 (23.8%) to netilmicin. The aac(6')-Ie-aph(2″) was the most frequent gene among MRSA isolates 19 (45.2%), followed by aph(3')-IIIa 8 (19%), ant(4')-Ia 6 (14.3%), and aph(2″)-Id 2 (4.8%). SCCmec types included type I 10 (23.8%), II 1 (2.4%), III 21 (50%), and IV 7 (16.7%). Three (7.2%) isolates were nontypeable. Digestion of the PCR products of the coa gene yielded 19 distinct restriction fragment length polymorphism patterns. In conclusion, given the alarming rate of resistance to aminoglycosides among MRSA, the monitoring of aminoglycoside resistance and AME genes should be performed to limit the spread of aminoglycoside resistance among MRSA isolates. Several variants of the coa gene were found in the studied isolates, although the majority of the MRSA isolates belonged to a limited number of coagulase types.

Coagulase gene polymorphism, enterotoxigenecity, biofilm production, and antibiotic resistance in Staphylococcus aureus isolated from bovine raw milk in North West India

Background

Staphylococcus aureus is the predominant bacterium responsible for various diseases in animals and humans. Preventive strategies could be better implemented by understanding the prevalence, genetic patterns, and the presence of enterotoxin and biofilm-producing genes along with the antibiotic susceptibility of this organism. This study was conducted in Rajasthan, the northwestern state of India, holding the largest population of cattle that makes it the second largest milk producer in India and no such prior information is available on these aspects.

Methods

A total of 368 individual quarter bovine raw milk samples were collected from 13 districts of Rajasthan, and screened for the presence of S. aureus. Microbiological and molecular approaches were followed for bacterial identification. Genetic diversity was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) of coagulase gene (coa), whereas enterotoxin and biofilm-producing genes were studied by PCR analysis. Antibiotic strips were employed to study the antibiotic resistance among strains.

Results

In all, 73 S. aureus strains were obtained from 368 bovine raw milk samples out of that only 30 showed the presence of coa. Nine types of coa patterns ranging from 730 to 1130 bp were observed among these isolates. PCR–RFLP of coa distinguished the isolates into 15 genotypic patterns, of which patterns I, IV, V, and VI were predominant. Of the isolates, 30% were positive for sec, 10% for sea, and 3.3% for seb; these genes are responsible for enterotoxin production, whereas all isolates were found positive for icaAD and eno. The prevalence rates of other biofilm-producing genes fnbA, clfB, ebpS, sasG, fnbB, sasC, cna, bap, fib and, bbp were 97, 93, 90, 80, 80, 77, 53, 27, 10, and 6.6%, respectively. Twenty-seven (90%) strains were multidrug resistant, of which 15 were methicillin resistant. Maximum sensitivity was reported for kanamycin and it could be considered as a drug of choice for controlling S. aureus mediated cattle infections in the studied regions.

Conclusions

Overall, these strains could cause several diseases to humans, insisting the need for developing a stricter hygiene program for improving milking practices and animal health.

Nasal carriage of methicillin-resistant Staphylococcus aureus and the effect of tea extracts on isolates

OBJECTIVES

This study aimed to determine the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage among patients, healthcare workers (HCWs), and community individuals, as well as to test the effect of tea extracts on detected S. aureus isolates.

MATERIALS AND METHODS

This cross-sectional study that was followed by an experimental study included a total of 1021 nasal swab samples that were collected from 470 community cases, 191 HCWs, and 360 patients. Isolation of S. aureus and MRSA was carried out on mannitol salt agar plates. S. aureus isolates were identified according to standard microbiological methods. Methicillin resistance was determined by disc-diffusion method according to the Clinical and Laboratory Standard Institute recommendations. A total of six tea samples (black and green) were purchased from different markets in Alexandria and were extracted. The antibacterial effects of these tea extracts were tested against identified MRSA isolates using agar gel diffusion method.

RESULTS

The overall S. aureus nasal carriage rate was 12.5%, distributed as 7.9% MRSA and 4.6% methicillin-susceptible S. aureus. The rates of MRSA nasal carriage among HCWs, patients, and community cases were 10.5, 8.1, and 6.8%, respectively. Green tea had a strong effect on more than half of the isolates (55%) and an intermediate effect on 45% of them. It had no weak effect on any of the MRSA isolates.

CONCLUSION

Among all tested individuals, HCWs had the highest percentage of MRSA nasal carriage. Green tea had a significantly stronger inhibitory effect than black tea on almost all tested isolates.

Microbial Etiology of Community-Acquired Pneumonia Among Infants and Children Admitted to the Pediatric Hospital, Ain Shams University

BACKGROUND

While recognizing the etiology of community-acquired pneumonia is necessary for formulating local antimicrobial guidelines, limited data is published about this etiology in Egyptian pediatric patients.

OBJECTIVES

To determine the frequency of bacterial and viral pathogens causing community-acquired pneumonia (CAP) among immunocompetent Egyptian infants and preschool children.

METHODS

Ninety infants and preschool-age children admitted to our hospital with CAP were prospectively included in the study. Etiological agents were identified using conventional bacteriological identification methods and IgM antibodies detection against common atypical respiratory bacteria and viruses.

RESULTS

An etiology was identified in 59 patients (65.5%). Bacterial pathogens were detected in 43 (47.8%) of the cases while viral pathogens were detected in 23 (25.5%). Coinfection with more than one etiologic agent was evident in seven patients (7.8%). The most common typical bacterial cause of pneumonia was Staphylococcus aureus (n = 12, 13.3%), followed by Streptococcus pneumoniae and Klebsiella pneumoniae (n = 7, 7.8%, each). The commonest atypical bacterium was Mycoplasma pneumoniae (n = 10, 11.1%), whereas the commonest viral etiology was influenza viruses (n = 11, 12.2%).

CONCLUSION

Although we could not determine the causative agent in some studied cases, this study provides preliminary data regarding the spectrum and frequency of microorganisms causing CAP in Egyptian infants and preschool children.