The Association of Panton-Valentine leukocidin and mecA Genes in Methicillin-Resistant Staphylococcus aureus Isolates From Patients Referred to Educational Hospitals in Ahvaz, Iran

Vaginal colonization with virulent and methicillin resistant Staphylococcus aureus among Ugandan women in Labour

BACKGROUND

Staphylococcus aureus (S. aureus) often colonizes the human skin, upper respiratory and genital tracts. In the female genital tract, it can be passed on to the newborn during vaginal delivery leading to either ordinary colonization, or neonatal infections notably umbilical stump sepsis, scalded skin syndrome, arthritis, or bacteraemia/sepsis. These infections are mediated by staphylococcal virulence factors such as (i) Staphylococcal Enterotoxins A, B, C, D, and E encoded by the sea, seb, sec, sed, see genes, (ii) Exfoliative Toxins A and B encoded by the eta and etb genes, (iii) Toxic Shock Syndrome Toxin 1 (TSST-1) encoded by the tst gene, (iv) Panton-Valentine Leukocidin (PVL) encoded by the pvl gene, and (v) Hemolysins alpha and delta encoded by the hla and hld genes, respectively. We determined the prevalence of S. aureus possessing one or more virulence factor genes and of methicillin resistant Staphylococcus aureus (MRSA) in this population.

METHODS

This was a cross-sectional study, which used 85 S. aureus isolates from the Chlorohexidine (CHX) clinical trial study in Uganda. The isolates had been obtained by culturing vaginal swabs (VS) from 1472 women in labour, frozen at minus 80oC, then thawed, sub-cultured, and tested for the selected virulence genes sea, seb, sec, sed, see eta, etb, tst, pvl, hla and hld, and for the methicillin resistance determining gene (mecA). Data were analyzed using SPSS version 20.

RESULTS

Of the 85 S. aureus isolates 13 (15.3%) were positive for one or more virulence factor genes, as follows: pvl 9/85 (10.6%), hld 5/85 (5.9%), sea 1/85 (1.2%) and seb genes 1/85 (1.2%). The other virulence genes (sec, sed, see, eta, etb, hla and tst) were not detected in any of the isolates. MRSA was detected in 55.3% (47/85) of the isolates, but only two of these carried the pvl virulence gene.

CONCLUSION

This study demonstrated that 15% of the S. aureus colonizing the female lower genital tract of mothers in labour in central Uganda carried one or more virulence genes, mostly pvl, indicating potential for newborn infection with S. aureus acquired in the maternal birth canal. More than half of the isolates were MRSA.

The examination of some virulence factors in S. aureus isolates obtained from the healthy human population, sheep mastitis, and cheese

Abstract.

Background

Staphylococcus aureus is responsible for many infections in humans and animals from skin and soft tissue infections to life-threatening diseases. In this study to explore the origin of S. aureus infections in humans, the antibiotic resistance profile and the variety of virulence factors in S. aureus isolates were examined in three groups: a healthy human population, cheese, and the milk of sheep with mastitis.

Aims

The examination of some virulence factors in S. aureus isolates obtained from the healthy human population, sheep mastitis, and cheese.

Methods

A total of 400 nasal swab samples from healthy students, 30 cheese samples, and 122 sheep milk samples were collected for the detection of S. aureus isolates from January 1, 2018, to March 1, 2018. The frequency of hla, hlb, Acme/arcA, pvl, and tsst-1 virulence genes and mecA gene was determined in each group by PCR assay.

Results

There was a direct relationship between the antibiotic susceptibility profile of the isolates from a healthy population and those from mastitis milk samples. Of 400 nasal samples, 15% (60/400) were positive for S. aureus, of which 60% (36/60) were positive for mecA. While 50% (15/30) of cheese samples were positive for S. aureus. of which 7 cases (46.66%, 7/15) were positive for mecA. The prevalence of S. aureus among students was dependent on gender (P=0.025). Also, 47.5% (58/122) of milk samples from sheep mastitis were positive for S. aureus, and 41.37% (24/58) were positive for the mecA gene. Based on PCR results, the highest rate of hla (68.33%, 41/60), hlb (53.33%, 32/60), and Acme/arcA (46.66%, 28/60) genes were related to a healthy population, and the highest frequency of pvl (41.38%, 24/58), and tsst-1 (27.59%, 16/58) was related to milk samples (P<0.05). A significant correlation was observed between the presence of the arginine catabolic mobile element (ACME)-arcA gene and resistance to methicillin (P<0.05).

Conclusion

The high rate of virulence factors in the S. aureus isolates obtained from mastitis and dairy products is an alert point, because they could be source of the spreading of S. aureus to humans. There is an essential need for continuous monitoring to control staphylococcal food poisoning.

The prevalence of Staphylococcus aureus and methicillin resistant Staphylococcus aureus in milk and dairy products in Riyadh, Saudi Arabia

In terms of life- menaced contagion, methicillin resistant Staphylococcus aureus (MRSA) is known to be one of which and it is truly notable in the contaminated food causing a community health anxiety. However, the occurrence of S. aureus and MRSA in diverse kinds of dairy products have been tested in this study. Samples from: raw milk (unpasteurized) from horse, goat, camel, and cow origins and unpacked cheese were checked for the recovered strains of such bacterium and MRSA. Wholly, MRSA isolates were verified for antimicrobial susceptibility and further characterized by mecA and staphylococcal cassette chromosome mec (SCCmec) typing. Also, Panton-Valentine Leukocidin (PVL), Staphylococcus aureus protein A (spa), and Staphylococcal enterotoxins (SEs) were also tested between all positive MRSA isolates in order to discover the virulence factors. Consequently, 70% of the 100 collected dairy products samples were contaminated by S. aureus bacteria and 72.9% of them were defined as MRSA. 9.8% of MRSA isolates contained mecA genes with SCCmec type II (80%) as the most common SCCmec type. Moreover, large number of MRSA isolates were identified as multidrug resistance and 28.6% of MRSA-mecA positive isolates were also carried vancomycin resistance genes (i.e., vanB). Too, spa gene was detected between 9.8% of MRSA isolates but PVL gene was not spotted at all. Additionally, the existing of SEs was variable between MRSA isolates and the most common type was SEH (51%). In general, our results confirmed that raw milk and unpacked cheese in the Kingdom of Saudi Arabia (Riyadh) is a potential vehicle for multidrug resistant MRSA transmission. It is a critical civic health menace and stresses, thus; the need of applying well cleanliness practices is essential.

Prevalence of PVL and LucED Genes in Methicillin-Resistant and Susceptible Isolates of Staphylococcus aureus Isolated from Burn Patients in Kermanshah, Iran

Background: The main pathogen causing various nosocomial infections, especially in burn patients, is Staphylococcus aureus. An important virulence factor of this bacterium is leukocidin, which binds to white blood cells and leads to apoptosis and necrosis. Objectives: In the present research, we aimed at investigating the prevalence of the panton-valentine leukocidin (PVL) and LucED genes in methicillin-susceptible and resistant isolates of S. aureus isolated from burn patients in Kermanshah, Iran. Methods: Overall, 73 isolates of S. aureus were collected from burn wounds and identified by specific biochemical tests. After determining the susceptibility patterns of the isolates by the disc diffusion method, the frequencies of the PVL and LucED genes were assessed using specific primers and polymerase chain reactions. Results: The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) isolates were 58.9% (43 isolates) and 41.1% (30 isolates), respectively. In MRSA isolates, the highest antibiotic resistance was to penicillin (100%) and gentamicin (81.4%). Moreover, the frequencies of the LucED and PVL genes were 76.7% (56 isolates) and 27.4% (20 isolates), respectively, and the highest frequency of the LucED and PVL genes was observed in MRSA (81.4%) and MSSA (40%) isolates, respectively. Conclusions: Increased multidrug resistance pattern among S. aureus isolates with leukocidin production has led to treatment failure and severe infections. The development of infections can be prevented by the identification of isolates carrying the leukocidin gene, and early detection of MRSA isolates is feasible by using the PVL gene.

The Prevalence of Staphylococcus aureus and Methicillin Resistant Staphylococcus aureus in Processed Food Samples in Riyadh, Saudi Arabia

Staphylococcus aureus mainly Methicillin Resistant Staphylococcus aureus(MRSA) is a life-threatening infection that occurring in food and caused a public health concern. This study designed to examine the prevalence of S. aureus and MRSA in different types of processed food. Food samples were screened for the recovered strains of S. aureus and MRSA, and they were examined for antimicrobial susceptibility and by molecular characterization of mecA and staphylococcal cassette chromosome mec(SCCmec). Detection of virulence factors like Panton-Valentine Leukocidin (PVL), Staphylococcus aureus protein A(spa) and Staphylococcal enterotoxins(SEs) by PCR using specific primers. Among the 150 collected processed food samples, 62.7% were contaminated by S. aureus bacteria, 56.4% of which were proved as MRSA. 17% of MRSA isolates were positive for mecA genes with the SCCmec type IVb and V (11.1% each) as the solely existing types of SCCmec. None of the MRSA isolates carried mecC or mecB genes. Most of MRSA isolates were multidrug resistance and 33.3% of MRSA-mecA positive isolates also carried vancomycin resistance genes (i.e., vanB). In addition, spa gene was found among 7.5% of MRSA isolates; none of which were positive for PVL gene. Further, there were variant presence of SEs among MRSA isolates and the highest presence was from type SEH (49.1%). Generally, our results confirmed that processed foods in Saudi Arabia (Riyadh) are potential vehicles for multidrug resistant S. aureus and MRSA transmission; which are serious public health risks, and underlined the need for good hygiene practices.

NASAL CARRIAGE OF MULTI-DRUG RESISTANT PANTON VALENTINE LEUKOCIDIN POSITIVE STAPHYLOCOCCUS AUREUS IN HEALTHY INDIVIDUALS OF TUDUN-WADA, GOMBE STATE, NIGERIA

Background:

Panton-Valentine Leucocidin (PVL)-producing Staphylococcus aureus strains have been implicated in serious community-associated invasive infections and their increasing multidrug resistance is a major global health concern. Thus, we investigated the prevalence of the PVL gene and the antimicrobial resistance profile of nasal S. aureus isolates from healthy adults in Tundu-Wada, Gombe State of Nigeria.

Methods and Materials:

A total of 262 nasal samples from healthy adults were obtained and cultured. The isolates were identified as S. aureus by standard morphological and biochemical methods alongside with the Polymerase Chain Reaction (PCR) amplification of their 16S rRNA gene. Antimicrobial susceptibility testing was performed by the disc diffusion technique and the presence of mecA and PVL genes was determined by PCR analysis.

Results:

The overall nasal colonization of S. aureus was 17.6%. The prevalence of haemolysin and biofilm production among the isolates was 25(54.3%) and 42(91.3%), respectively. Only 2(4.3%) and 5(10.9%) possessed mecA and PVL genes respectively but none of the isolates harboured these two genes. All the isolates were resistant to amoxicillin but were highly susceptible (93.7%) to gentamicin. The prevalence of multi-drug resistance (MDR) among the isolates was M 45.7% and all PVL-producing isolates were MDR while one of the isolates with mecA gene exhibited extensive-drug resistance (XDR).

Conclusion:

This is the first report of nasal colonization of MDR PVL-producing S. aureus in healthy adults in Gombe, Northeastern Nigeria. This study highlights the importance of routine surveillance of healthy populations to provide useful strategies for controlling the spread of virulent multidrug-resistant organisms within the community.

Methicillin-resistant Staphylococcus aureus nasal carriage between healthy students of medical and nonmedical universities

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a challenge for public health, and community-acquired (CA) infections seem to be increasing among people in different areas.

METHODS

A total of 700 healthy student volunteers residing in dormitories of universities in Urmia, Iran, were enrolled in this study. After identification of the isolates, antibiotic susceptibility, presence of mecA and pvl genes, and staphylococcal cassette chromosome mec (SCCmec) typing were evaluated.

RESULTS

Nasal screening identified 137 (19.6%) carriers of S aureus, and 18 (13.14%) were MRSA isolates. The antimicrobial susceptibility patterns of isolates revealed high resistance to penicillin (93.4%). All isolates were sensitive to vancomycin. The SCCmec typing showed that most MRSA strains belonged to SCCmec type IV (n = 14; 77.8%). Only 1 (5.56%) MRSA isolates carried the pvl gene.

CONCLUSIONS

Our findings revealed the relatively high frequency of S aureus nasal carriers and the advent of multidrug resistance among these isolates. Most MRSA isolates were SCCmec type IV; the transfer of such MRSA strains from carriers to other individuals in crowded living conditions such as dormitories can act as a risk factor for outbreak of CA MRSA and is a serious threat for the study groups.

Molecular characterisation of Panton-Valentine leucocidin-producing methicillin-resistant Staphylococcus aureus clones isolated from the main hospitals in Taif, KSA

INTRODUCTION

Panton-Valentine leucocidin (PVL) is a bicomponent pore-forming cytolytic toxin encoded by the lukF-PV and lukS-PV genes. Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) may carry the pvl genes which may be related to increased disease severity. This study aimed to characterise the PVL-producing MRSA recovered from different Taif Hospitals, Saudi Arabia.

METHODS

The study included 45 hospital-acquired-MRSA (HA-MRSA) and 26 CA-MRSA strains which were identified from 445 S. aureus strains isolated from different clinical samples. MRSA strains were identified by standard oxacillin salt agar screening procedure and by the detection of the mecA gene by the polymerase chain reaction (PCR). Detection of the S. aureus-specific femA, mecA and pvl genes was performed by multiplex PCR. PCR-restriction fragment length polymorphism (PCR-RFLP) analysis was done for coagulase (coa) gene.

RESULTS

The staphylococcal cassette chromosome mec types of the 45 HA-MRSA strains were Type I (n = 24), Type II (n = 7) and Type III (n = 14) whereas the 26 CA-MRSA strains were Type IV (n = 14), Type V (n = 11) and one isolate was non-typeable. All the HA-MRSA and six CA-MRSA strains were PVL-negative PCR-RFLP analysis of coa gene showed that PVL-positive MRSA (n = 20) isolates showed six different patterns, and five patterns were shared by PVL-positive methicillin-susceptible S. aureus (MSSA). The eighth pattern was the most frequent in both MRSA and MSSA.

CONCLUSION

PVL is more frequent among CA-MRSA than MSSA. All the HA-MRSA and 25% of CA-MRSA strains were negative for PVL. The pvl gene was related to the severity of infection but not related to coa gene RFLP pattern.

Staphylococcus aureus Toxins and Diabetic Foot Ulcers: Role in Pathogenesis and Interest in Diagnosis

Infection of foot ulcers is a common, often severe and costly complication in diabetes. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. The numerous virulence factors and toxins produced by S. aureus during an infection are well characterized. However, some particular features could be observed in DFI. The aim of this review is to describe the role of S. aureus in DFI and the implication of its toxins in the establishment of the infection. Studies on this issue have helped to distinguish two S. aureus populations in DFI: toxinogenic S. aureus strains (harboring exfoliatin-, EDIN-, PVL- or TSST-encoding genes) and non-toxinogenic strains. Toxinogenic strains are often present in infections with a more severe grade and systemic impact, whereas non-toxinogenic strains seem to remain localized in deep structures and bone involving diabetic foot osteomyelitis. Testing the virulence profile of bacteria seems to be a promising way to predict the behavior of S. aureus in the chronic wounds.

Multidrug resistance pattern of bacterial agents isolated from patient with chronic sinusitis

BACKGROUND

Treatment of chronic sinusitis is complicated due to increase of antibiotic-resistant bacteria. The aim of this study was to determine the multidrug resistance (MDR) pattern of the bacteria causing chronic sinusitis in north of Iran.

METHODS

This cross-sectional study was carried out on patients with chronic sinusitis. Bacterial susceptibility to antimicrobial agents was determined according to the CLSI 2013 standards. Double-disk synergy (DDS) test was performed for the detection of extended-spectrum beta-lactamase (ESBL) producing bacteria; also methicillin-resistant Staphylococcus (MRSA) strains were identified by MRSA screen agar. The MDR isolates were defined as resistant to 3 or more antibiotics. Data were analyzed using SPSS 17 software. Descriptive statistics was used to describe the features of the data in this study.

RESULTS

The rate of ESBL-producing bacteria was 28.75-37.03% among enterobacteriaceae and the rate of MRSA was 42.75%-60% among Staphylococcus strains. The most detectable rate of the MDR bacterial isolates was Gram-negative bacteria 39 (76.47%) and Enterobacter spp. 19(70.37%) was the most multidrug resistant isolate among Gram negative bacteria. Also 36 (73.46%) of the gram positive bacterial isolated were multidrug resistance and Staphylococcus aureus 9(90%) was the most MDR among Gram positive bacteria.

CONCLUSION

Antimicrobial resistance is increasing in chronic bacterial sinusitis. The emergence of MRSA and ESBL bacteria causing chronic sinusitis is increasing.