Staphylococcus aureus isolates carrying Panton-Valentine leucocidin genes in England and Wales: frequency, characterization, and association with clinical disease

Epidemiology and clinical features of Skin and Soft Tissue Infections Caused by PVL-Positive and PVL-Negative Methicillin-Resistant Staphylococcus aureus Isolates in inpatients in China: a single-center retrospective 7-year study

Previous studies have mainly focused on outpatient cases of skin and soft tissue infections (SSTIs), with limited attention to inpatient occurrences. Thus, we aimed to compare the clinical parameters of inpatients with SSTIs, performed genomic characterization, and determined the subtypes of Panton-Valentine leucocidin (PVL) bacteriophages of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from these patients. We found that PVL-positive patients had shorter hospital stays (mean, 9 vs. 24 days; p < 0.001) and abscess resolution durations (mean, 8 vs. 13 days; p < 0.01). PVL-positive MRSA-induced SSTIs were more frequently associated with abscesses [36/55 (65.5%) vs. 15/124 (12.1%), p < 0.001], with 52.7% undergoing incision and drainage; over 80% of PVL-negative patients received incision, drainage, and antibiotics. In PVL-positive patients receiving empirical antibiotics, anti-staphylococcal agents such as vancomycin and linezolid were administered less frequently (32.7%, 18/55) than in PVL-negative patients (74.2%, 92/124), indicating that patients with PVL-positive SSTIs are more likely to require surgical drainage rather than antimicrobial treatment. We also found that the ST59 lineage was predominant, regardless of PVL status (41.3%, 74/179). Additionally, we investigated the linear structure of the lukSF-PV gene, revealing that major clusters were associated with specific STs, suggesting independent acquisition of PVL by different strain types and indicating that significant diversity was observed even within PVL-positive strains detected in the same facility. Overall, our study provides comprehensive insights into the clinical, genetic, and phage-related aspects of MRSA-induced SSTIs in hospitalized patients and contributes to a more profound understanding of the epidemiology and evolution of these pathogens in the Chinese population.

HIV and skin infections

HIV infection alters the skin microbiome and predisposes to a wide range of cutaneous infections, from atypical presentations of common skin infections to severe disseminated infections involving the skin that are AIDS-defining illnesses. Bacterial infection of the skin, most commonly caused by Staphylococcus aureus, occurs frequently and can result in bacteremia. Nontuberculous mycobacterial infections that are usually localized to the skin may disseminate, and guidance on the treatment of these infections is limited. Herpes simplex can be severe, and less common presentations such as herpetic sycosis and herpes vegetans have been reported. Severe herpes zoster, including disseminated infection, requires intravenous antiviral treatment. Viral warts can be particularly difficult to treat, and in atypical or treatment-resistant cases a biopsy should be considered. Superficial candidosis occurs very commonly in people living with HIV, and antifungal resistance is an increasing problem in non-albicans Candida species. Systemic infections carry a poor prognosis. In tropical settings the endemic mycoses including histoplasmosis are a problem for people living with HIV, and opportunistic infections can affect those with advanced HIV in all parts of the world. Most cutaneous infections can develop or worsen as a result of immune reconstitution in the weeks to months after starting antiretroviral therapy. Direct microscopic examination of clinical material can facilitate rapid diagnosis and treatment initiation, although culture is important to provide microbiological confirmation and guide treatment.

Rate of Beta-Lactam Resistance and Epidemiological Features of S. Aureus-Associated Bovine Mastitis in Cross-Bred Ethiopian Cows: Systematic Review

Background

Dairy cows get mastitis from a common infection called Staphylococcus aureus. Because of its broad distribution across diverse populations and capacity to acquire antibiotic resistance, this particular bacterial strain presents a serious threat to public health. The main goals of this study were to determine the beta-lactam resistance profile of S. aureus in Ethiopian dairy cows and to offer thorough epidemiological data.

Methods

We employed manual searches, Web of Science, PubMed Central, and Google Scholar HINARI for electronic bibliographic data.

Results

Twenty-six epidemiological studies were included in this systematic review. Of these studies, 12 articles in Oromia, 4 articles in Addis Ababa, 4 articles in Southern Nations, Nationalities, and People's (SNNPRS), 3 articles in Tigray, and 3 articles in Amhara region. The average prevalence S. aureus were 34.3% in Oromia, 40.2% in Amhara, 39.5 in AA, 40% in Tigray and 21% in SNNPRS. The antimicrobial resistance rate of S. aureus, specifically in relation to beta-lactam drugs, exhibited an average estimation. Notably, penicillin resistance reached a rate of 75%, while amoxicillin resistance stood at 67%. Furthermore, it was determined that, when treating S. aureus, the resistance rates to ampicillin and cephalosporin were 50% and 57%, respectively.

Conclusion

The results of this analysis have demonstrated a considerable rise in S. aureus prevalence and beta-lactam resistance within the Ethiopian geographic environment. This emphasizes the critical need for alternate therapeutic approaches and preventative measures in order to successfully lessen the disease's extensive spread and detrimental effects across the nation.

Ocular Bacterial Infections: A Ten-Year Survey and Review of Causative Organisms Based on the Oklahoma Experience

Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection. This survey of ocular bacterial isolates and review of ocular pathogens is based on a survey of a collection of isolates banked over a ten-year span at the Dean McGee Eye Institute in Oklahoma. These findings illustrate the diversity of bacteria isolated from the eye, ranging from common species to rare and unique species. At all sampled sites, staphylococci were the predominant bacteria isolated. Pseudomonads were the most common Gram-negative bacterial isolate, except in vitreous, where Serratia was the most common Gram-negative bacterial isolate. Here, we discuss the range of ocular infections that these species have been documented to cause and treatment options for these infections. Although a highly diverse spectrum of species has been isolated from the eye, the majority of infections are caused by Gram-positive species, and in most infections, empiric treatments are effective.

Prevalence of mecA and Panton-Valentine Leukocidin Genes in Staphylococcus aureus Clinical Isolates from Gaza Strip Hospitals

Methicillin-resistant Staphylococcus aureus (MRSA) are spreading worldwide in hospital and community settings, thus posing a serious public health problem. Panton-Valentine Leukocidin (PVL), an important virulence factor of S. aureus, is a marker of community-acquired MRSA. Here we determined the prevalence of pvl genes among S. aureus isolates from different hospitals in the Gaza Strip, Palestine. A total of 285 S. aureus isolates were collected from five different hospitals in the Gaza Strip. All isolates were characterized for their susceptibility patterns to available antimicrobial agents and by using multiplex PCR for the detection of mecA and pvl genes. The overall prevalence of MRSA in Gaza hospitals was 70.2% (range: 76.3% to 65.5%) and that of pvl among S. aureus isolates was 29.8% (range: 32.9% to 26.2%). The pvl gene was equally prevalent among MRSA isolates (30.5%) and MSSA isolates (28.2%). The most effective antibiotics were rifampicin, vancomycin, and clindamycin, with susceptibility rates of 91.2%, 88.7%, and 84.6%, respectively. The highest percentage of strains were observed to be resistant to penicillin and amoxicillin with clavulanic acid-96.1% and 73.6%, respectively. Our results showed a high prevalence of MRSA and pvl-positive isolates in Gaza Strip hospitals, which likely reflects the situation in the community. It is mandatory to implement systematic surveillance of both hospital and community isolates, together with interventions (such as increased hand hygiene, use of hydroalcoholic solutions, and isolation of carriers) to limit their spread.

Examining the Prevalence and Antibiotic Susceptibility of S. aureus Strains in Hospitals: An Analysis of the pvl Gene and Its Co-Occurrence with Other Virulence Factors

S. aureus is a pathogenic bacterium that causesinfections. Its virulence is due to surface components, proteins, virulence genes, SCCmec, pvl, agr, and SEs, which are low molecular weight superantigens. SEs are usually encoded by mobile genetic elements, and horizontal gene transfer accounts for their widespread presence in S. aureus. This study analyzed the prevalence of MRSA and MSSA strains of S. aureus in two hospitals in Greece between 2020–2022 and their susceptibility to antibiotics. Specimens collected were tested using the VITEK 2 system and the PCR technique to detect SCCmec types, agr types, pvl genes, and sem and seg genes. Antibiotics from various classes were also tested. This study examined the prevalence and resistance of S. aureus strains in hospitals. It found a high prevalence of MRSA and that the MRSA strains were more resistant to antibiotics. The study also identified the genotypes of the S. aureus isolates and the associated antibiotic resistances. This highlights the need for continued surveillance and effective strategies to combat the spread of MRSA in hospitals. This study examined the prevalence of the pvl gene and its co-occurrence with other genes in S. aureus strains, as well as their antibiotic susceptibility. The results showed that 19.15% of the isolates were pvl-positive and 80.85% were pvl-negative. The pvl gene co-existed with other genes, such as the agr and enterotoxin genes. The results could inform treatment strategies for S. aureus infections.

Antibiogram, prevalence of methicillin-resistant and multi-drug resistant Staphylococcus spp. in different clinical samples

Methicillin-resistant Staphylococcus spp. (MRSS) are causing numerous forms of illness in humans ranging from mild to fatal infections. We need to investigate the resistant pattern for different clinical isolates to control the resistance phenomena. This study was designed to provide the resistance pattern of isolated Staphylococcus spp. from various clinical samples in Khartoum State and to elucidate the frequencies of Multidrug-resistant (MDR), Extensively drug-resistant (XDR) and pan-drug resistant (PDR). Two hundred and ten bacterial isolates were from different sources (catheter tip, sputum, vaginal swab, urine, tracheal aspirate, blood, pus, nasal swab, stool, throat swab, pleural fluid, and ear swab). Isolates were identified based on their morphological characters and biochemical reaction. Antibiotics susceptibility screening was performed using twenty-three antibiotics from eighteen classes against all isolated Staphylococcus spp. following the Clinical and Laboratory Standards Institute (CLSI) guideline. The result revealed that out of 63 Gram-positive isolated bacteria, 52 (82.5%) were Staphylococcus spp. with a high incidence of S. aureus 37(71.2%). Out of all Staphylococcus spp., 38 (73.1%) were Methicillin-resistant (MR). The prevalence of MDR was higher in S. aureus (89.2%) than in S. epidermidis (75%). All Staphylococcus spp. displayed resistance to ampicillin and penicillin, while all S. aureus were sensitive to daptomycin and fosfomycin. One isolate was XDR possible PDR, while no PDR was reported in all isolated bacteria. This study provided evidence for the antimicrobial-resistant (AMR) burden in Sudan and highlighted the need for a practical and functional stewardship program to reduce the unreasonable costs of antibiotics.

Multi-Drug Resistant Staphylococcus aureus Carriage in Abattoir Workers in Busia, Kenya

Abattoir workers have been identified as high-risk for livestock-associated Staphylococcus aureus carriage. This study investigated S. aureus carriage in abattoir workers in Western Kenya. Nasal swabs were collected once from participants between February-November 2012. S. aureus was isolated using bacterial culture and antibiotic susceptibility testing performed using the VITEK 2 instrument and disc diffusion methods. Isolates underwent whole genome sequencing and Multi Locus Sequence Types were derived from these data. S. aureus (n = 126) was isolated from 118/737 (16.0%) participants. Carriage was higher in HIV-positive (24/89, 27.0%) than HIV−negative participants (94/648, 14.5%; p = 0.003). There were 23 sequence types (STs) identified, and half of the isolates were ST152 (34.1%) or ST8 (15.1%). Many isolates carried the Panton-Valentine leucocidin toxin gene (42.9%). Only three isolates were methicillin resistant S. aureus (MRSA) (3/126, 2.4%) and the prevalence of MRSA carriage was 0.4% (3/737). All MRSA were ST88. Isolates from HIV-positive participants (37.0%) were more frequently resistant to sulfamethoxazole/trimethoprim compared to isolates from HIV-negative participants (6.1%; p < 0.001). Similarly, trimethoprim resistance genes were more frequently detected in isolates from HIV-positive (81.5%) compared to HIV-negative participants (60.6%; p = 0.044). S. aureus in abattoir workers were representative of major sequence types in Africa, with a high proportion being toxigenic isolates. HIV-positive individuals were more frequently colonized by antimicrobial resistant S. aureus which may be explained by prophylactic antimicrobial use.

Attenuating the virulence of the resistant superbug Staphylococcus aureus bacteria isolated from neonatal sepsis by ascorbic acid, dexamethasone, and sodium bicarbonate

Background

Infections affecting neonates caused by Staphylococcus aureus are widespread in healthcare facilities; hence, novel strategies are needed to fight this pathogen. In this study, we aimed to investigate the effectiveness of the FDA-approved medications ascorbic acid, dexamethasone, and sodium bicarbonate to reduce the virulence of the resistant Staphylococcus aureus bacteria that causes neonatal sepsis and seek out suitable alternatives to the problem of multi-drug resistance.

Methods

Tested drugs were assessed phenotypically and genotypically for their effects on virulence factors and virulence-encoding genes in Staphylococcus aureus. Furthermore, drugs were tested in vivo for their ability to reduce Staphylococcus aureus pathogenesis.

Results

Sub-inhibitory concentrations (1/8 MIC) of ascorbic acid, dexamethasone, and sodium bicarbonate reduced the production of Staphylococcus aureus virulence factors, including biofilm formation, staphyloxanthin, proteases, and hemolysin production, as well as resistance to oxidative stress. At the molecular level, qRT-PCR was used to assess the relative expression levels of crtM, sigB, sarA, agrA, hla, fnbA, and icaA genes regulating virulence factors production and showed a significant reduction in the relative expression levels of all the tested genes.

Conclusions

The current findings reveal that ascorbic acid, dexamethasone, and sodium bicarbonate have strong anti-virulence effects against Staphylococcus aureus. Thus, suggesting that they might be used as adjuvants to treat infections caused by Staphylococcus aureus in combination with conventional antimicrobials or as alternative therapies.

Case Report: Necrotizing fasciitis caused by Staphylococcus aureus positive for a new sequence variant of exfoliative toxin E

Objectives: Necrotizing fasciitis (NF) caused by S. aureus is a rare, aggressive and rapidly progressing superficial fascia infection with a high mortality rate. The aim of this study was to identify virulence-related genes from a complete genome sequence of a methicillin-susceptible S. aureus (MSSA) isolate recovered from a monomicrobial case of NF.

Materials and methods: The MSSA isolate UMCG579 was cultured from a pus collection from the subcutis of a patient with NF. The genome of isolate UMCG579 was sequenced using MinION (Oxford Nanopore) and MiSeq (illumina) platforms.

Results: The genome of the UMCG579 isolate was composed of a 2,741,379 bp chromosome and did not harbor any plasmids. Virulence factor profiling identified multiple pore-forming toxin genes in the UMCG579 chromosome, including the Panton-Valentine leukocidin (PVL) genes, and none of the superantigen genes. The UMCG579 isolate harbored a new sequence variant of the recently described ete gene encoding exfoliative toxin (type E). A search in the GenBank database revealed that the new sequence variant (ete2) was exclusively found among isolates (n = 115) belonging to MLST CC152. While the majority of S. aureus ete-positive isolates were recovered from animal sources, S. aureus ete2-positive isolates originated from human carriers and human infections. Comparative genome analysis revealed that the ete2 gene was located on a 8777 bp genomic island.

Conclusion: The combination of two heterogeneously distributed potent toxins, ETE2 and PVL, is likely to enhance the pathogenic ability of S. aureus isolates. Since anti-virulence therapies for the treatment of S. aureus infections continue to be explored, the understanding of specific pathogenetic mechanisms may have an important prophylactic and therapeutic value. Nevertheless, the exact contribution of ETE sequence variants to S. aureus virulence in NF infections must be determined.

Molecular Evolution and Genomic Insights into Community-Acquired Methicillin-Resistant Staphylococcus aureus Sequence Type 88

Sequence type 88 (ST88) methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an important pathogen that causes infections in humans, especially when it has strong biofilm production and multidrug resistance (MDR). However, knowledge of the determinants of resistance or virulence and genomic characteristics of ST88 MRSA from China is still limited. In this study, we employed the antimicrobial resistance (AMR), biofilm formation, and genomic characteristics of ST88 MRSA collected from various foods in China and estimated the worldwide divergence of ST88 MRSA with publicly available ST88 genomes. All ST88 isolates studied were identified as having resistance genes, while 50% (41/82) harbored MDR genes. All isolates carried core virulence genes related to immune modulation, adherence, secreted enzymes, and hemolysin. In addition, all 20 Chinese ST88 isolates showed biofilm production capacity, three strongly so. Bayesian phylogenetic analysis showed that Chinese ST88 clones formed an independent MRSA lineage, with two subclades associated with acquisition of type IVc staphylococcal cassette chromosome mec (SCCmec) elements. In contrast, all African ST88 strains were subtyped as SCCmecIVa, where the African clades were mixed with a few European and American isolates, suggesting potential transmission from Africa to these regions. In summary, our results revealed the evolution of ST88 MRSA in humans, animals, and foods in Africa and Asia. The food-associated ST88 genomes in this study will remedy the lack of food-associated ST88 isolates, and the study in general will extend the discussion of the potential exchanges of ST88 between humans and foods or food animals.

IMPORTANCE ST88 MRSA has frequently been detected in humans, animals, and foods mainly in Africa and Asia. It can colonize and cause mild to severe infections in humans, especially children. Several studies from African countries have described its genotypic characteristics but, limited information is available on the evolution and characterization of ST88 MRSA in Asia, especially China. Meanwhile, the molecular history of its global spread remains largely unclear. In this study, we analyzed the genomic evolution of global ST88 MRSA strains in detail and identified key genetic changes associated with specific hosts or regions. Our results suggested geographical differentiation between ST88 MRSA’s evolution in Africa and its evolution in Asia, with a more recent clonal evolution in China. The introduction of ST88 MRSA in China was aligned with the acquisition of SCCmecIVc elements, specific virulent prophages, and AMR genes.

Evaluation of methicillin-resistant Staphylococcus virulence genes and antibiotics susceptibility in Iranian population

Background

Methicillin resistance Staphylococcus aureus (MRSA) is one most important pathogens for human health. The ability of this organism for producing different kinds of disease is related to its virulence gene. The frequency of hemolysin alpha (hla), hemolysin beta (hlb), and exfoliative toxin A (eta) virulence genes of MRSA was evaluated, and the association of these genes with antibiotics susceptibility was investigated.

Materials and Methods

In a cross-sectional study, a total of 695 Staphylococcus clinical samples from seven different provinces of Iran were evaluated. MRSA was detected by cefoxitin disk. Virulence genes were detected by polymerase chain reaction. Susceptibility to clindamycin and ciprofloxacin was evaluated according to the Clinical and Laboratory Standards Institute guideline.

Results

From a total of 695 samples, 170 (24.46%) were found to be MRSA. 142, 82, and 132 samples of MRSA were hla, hlb, and eta positive, respectively. hla gene was significantly found more frequently in patients at least 18 years (P = 0.02). 105 (68.6%) and 93 (59.6%) of MRSA samples were resistance to ciprofloxacin and clindamycin, respectively. hlb gene was significantly more resistant to clindamycin (P = 0.04) and ciprofloxacin (P = 0.01). Logistic regression analysis displayed hlb-positive MRSA strains were significantly associated with ciprofloxacin (odds ratio [OR]: 3.6, 95% confidence interval [CI] = 1.637-8.00) and clindamycin (OR: 1.93, 95% CI 1.00-3.68).

Conclusion

MRSA strains from Staphylococcus aureus which isolated from hospitalized Iranian patients are significantly resistant to clindamycin and ciprofloxacin and it is may be because of hlb virulence gene. These samples consist of both community-acquired MRS) and health-care associated MRSA, so we could not use this finding as a guide for local antibiotics usage.

Unusual skin manifestations in an elderly man

A 77-year-old man presented with a 2-month history of a widespread scaly erythematous patches affecting his trunk and limbs. This case report discusses the differential diagnosis in a patient with unusual lumps. It explores the common pitfalls in examining such cases and provides key learning points.

Is decolonisation to prevent PVL-positive Staphylococcus aureus infection in the population effective? A systematic review

INTRODUCTION

Panton-Valentine Leukocidin (PVL) producing Staphylococcus aureus is associated with recurrent skin and soft tissue infections and occasionally invasive infections. There is limited evidence to support current public health guidance on decolonisation of cases and household contacts.

METHODS

This systematic review (CRD42020189906) investigated the efficacy of decolonisation against PVL-positive S. aureus to inform future public health practice. It included studies of cases with PVL-positive infections providing information on the efficacy of decolonisation of cases, carriers, or contacts of cases. Studies were assessed for the risk of bias using the GRADE approach and summarised to inform a narrative synthesis.

RESULTS

The search identified 20, mostly observational, studies with small samples and lacking control groups. Studies with longer follow-ups found that, while early post-decolonisation screening was negative for most individuals, testing over subsequent months identified re-colonisation in some. There is no high quality evidence to show whether decolonisation is effective in reducing (re)infection or long-term carriage of PVL-positive S. aureus and the low quality evidence available indicates it may not be effective in eradicating carriage or reducing future disease. Furthermore, there may be risks associated with decolonisation, for example, potentially increased risk of infection from other microbes, opportunity costs and negative impacts of repeated testing for asymptomatic carriage.

CONCLUSIONS

Further research is required to better understand what affects the ability of decolonisation efforts to reduce risk to cases and their contacts, including strain, host and environmental factors.

The promising anti-virulence activity of candesartan, domperidone, and miconazole on Staphylococcus aureus

Staphylococcus aureus is a primary cause of hospital and community-acquired infections. With the emergence of multidrug-resistant S. aureus strains, there is a need for new drugs discovery. Due to the poor supply of new antimicrobials, targeting virulence of S. aureus may generate weaker selection for resistant strains, anti-virulence agents disarm the pathogen instead of killing it. In this study, the ability of the FDA-approved drugs domperidone, candesartan, and miconazole as inhibitors of S. aureus virulence was investigated. The effect of tested drugs was evaluated against biofilm formation, lipase, protease, hemolysin, and staphyloxanthin production by using phenotypic and genotypic methods. At sub-inhibitory concentrations, candesartan, domperidone, and miconazole showed a significant inhibition of hemolysin (75.8-96%), staphyloxanthin (81.2-85%), lipase (50-65%), protease (40-64%), and biofilm formation (71.4-90%). Domperidone and candesartan have similar activity and were more powerful than miconazole against S. aureus virulence. The hemolysins and lipase inhibition were the greatest under the domperidone effect. Candesartan showed a remarkable reduction in staphyloxanthin production. The highest inhibitory effect of proteolytic activity was obtained with domperidone and candesartan. Biofilm was significantly reduced by miconazole. Expression levels of crtM, sigB, sarA, agrA, hla, fnbA, and icaA genes were significantly reduced under candesartan (68.98-82.7%), domperidone (62.6-77.2%), and miconazole (32.96-52.6%) at sub-MIC concentrations. Candesartan showed the highest inhibition activity against crtM, sigB, sarA, agrA, hla, and icaA expression followed by domperidone then miconazole. Domperidone showed the highest downregulation activity against fnbA gene. In conclusion, candesartan, domperidone, and miconazole could serve as anti-virulence agents for attenuation of S. aureus pathogenicity.

Detection of Panton-Valentine leukocidin and MecA Genes in Staphylococcus aureus isolated from Iraqi Patients

A gram-positive bacterium, Staphylococcus aureus, which is widely distributed is considered as a bacterial infection that commonly infects the skin and mucous membranes. Such infections can be the cause of death and illness. In the present study by using reverse transcription-polymerase chain reaction (rt-PCR) the Panton-Valentine leukocidin (PVL) and MecA genes of S. aureus which were isolated from skin and soft tissue infections (SSTIs) in Baghdad, Iraq were investigated. This study included 96 S. aureus isolated from SSTIs and identified by Vitek. The results showed that 61 (63.5%) and 48 (50%) of the isolates were positive for PVL and MecA genes, respectively. This work presented an effective real-time PCR technique for detecting PVL genes alone or in conjunction with MecA. The rt-PCR allows for easier reaction monitoring and eliminates the need for post-PCR processing, saving both resources and time. Moreover, it is ideal for diagnostic applications because of its high sensitivity, simplicity, and specificity. Besides, the rt-PCR has an option to do all the procedures in an automated mode of action.

Prevalence of Mastitis and Phenotypic Characterization of Methicillin-Resistant Staphylococcus aureus in Lactating Dairy Cows of Selected Dairy Farms in and Around Adama Town, Central Ethiopia

BACKGROUND

The emergence of Methicillin resistant Staphylococcus aureus (MRSA) poses a serious public health threat. Strains of Staphylococcus aureus resistant to β-lactam antibiotics are known as MRSA. MRSA has gained attention as community pathogen. MRSA has been increasingly reported as emerging problem in veterinary medicine. However, little is known in Ethiopia. This study was, therefore, conducted to identify MRSA, to determine its drug susceptibility patterns, and mastitis infection in dairy cattle in and around Adama town, Central Ethiopia.

METHODS

A cross-sectional study was conducted to estimate the occurrence of MRSA in mastitic dairy cows in and around Adama town, central Ethiopia. A total of 384 lactating cows were included from the conveniently selected dairy farms in the study area. Approximately 10 ml of milk was aseptically collected from clinical and subclinical mastitic cows into sterile universal bottles after discarding the first 3 milking streams. Then, Staphylococcus aureus was isolated using the conventional bacteriological procedure. Resistance to methicillin was detected using the Kirby-Bauer disc diffusion antibiotic susceptibility method. Oxacillin disc was used to detect methicillin resistant Staphylococcus aureus strains. Antimicrobial susceptibility test was conducted against MRSA strains using streptomycin (S, 10 µg), amoxicillin (Am, 25 µg), kanamycin (k, 30 µg), nalidixic acid (NA, 30 µg), oxytetracycline (OT, 30 µg) sulphonamide (S, 300 µg) and ceftriazole (CRO, 30 µg).

RESULTS

The study found that the prevalence of mastitis was 121(31.5%). Among this 37(30.6%) were clinical mastitis and 84 (69.4%) of them were sub-clinical mastitis. Of 121 mastitis cases, Staphylococcus aureus was isolated in 37 (30.6%) of mastitic cow milk samples. The prevalence of mastitis was significantly affected by breed, age, floor type and hygienic status of the milkers (P < .05). Moreover, 32.4% of Staphylococcus aureus isolates were resistant to oxacillin. A total of 75% percent of MRSA isolates were resistant to amoxicillin, 66.7% were resistant to oxytetracycline, and 50% were resistant to sulphonamide. However, 75% of MRSA isolates were susceptible to kanamycin, 58.3% were susceptible to streptomycin, and 50% were susceptible to nalidixic acid.

CONCLUSION

The study revealed that relatively high number of strains are resistant to the antibiotics commonly used in the therapeutic protocol of many human and animal infections. Therefore, antimicrobial susceptibility test should be carried out at a regular basis and proper hygienic practices should be introduced at farm level. Creating public awareness about transmission, prevention and control of MRSA should also be considered.

Prognostic factors of severe community-acquired staphylococcal pneumonia in France

PURPOSE

Staphylococcus aureus causes severe forms of community-acquired pneumonia (CAP), namely staphylococcal pleuropneumonia in young children and staphylococcal necrotising pneumonia in older patients. Methicillin resistance and the Panton-Valentine leukocidin (PVL) toxin, as well as less specific factors, have been associated with poor outcome in severe CAP, but their roles are unclear.

METHODS

A prospective multicentre cohort study of severe staphylococcal CAP was conducted in 77 paediatric and adult intensive care units in France between January 2011 and December 2016. After age-clustering, risk factors for mortality, including pre-existing conditions, clinical presentation, laboratory features, strain genetic lineage, PVL, other virulence factors and methicillin resistance were assessed using univariate and multivariable Cox and LASSO (least absolute shrinkage and selection operator) regressions.

RESULTS

Out of 163 included patients, aged 1 month to 87 years, 85 (52.1%) had PVL-positive CAP; there were 20 (12.3%) patients aged <3 years (hereafter "toddlers"), among whom 19 (95%) had PVL-positive CAP. The features of PVL-positive CAP in toddlers matched with the historical description of staphylococcal pleuropneumonia, with a lower mortality (three (15%) out of 19) compared to PVL-positive CAP in older patients (31 (47%) out of 66). Mortality in older patients was predicted by PVL-positivity (hazard ratio (HR) 1.81, 95% CI 1.03-3.17) and methicillin resistance (HR 2.37, 95% CI 1.29-4.34) independently from S. aureus lineages and the presence of other determinants of virulence.

CONCLUSION

PVL was associated with staphylococcal pleuropneumonia in toddlers and was a risk factor for mortality in older patients with severe CAP, independently of methicillin resistance, S. aureus genetic background and other virulence factors.

Detection of methicillin-resistant coagulase-negative staphylococci and PVL/mecA genes in cefoxitin-susceptible Staphylococcus aureus (t044/ST80) from unpasteurized milk sold in stores in Djelfa, Algeria

This study was designed to determine antimicrobial resistance phenotypes and genotypes and virulence factors in Staphylococcus aureus and coagulase-negative staphylococci (CNS) in unpasteurized milk sold in Djelfa, Algeria. Eighty-two unpasteurized cow milk samples were randomly obtained from 82 retail stores in Djelfa and tested to detect staphylococci. Species were identified by biochemical tests and MALDI-TOF. Antimicrobial resistance phenotypes and genotypes were determined by disk diffusion test, PCR, and sequencing. The Staph. aureus isolates were subjected to spa typing, multilocus sequence typing, and detection of virulence genes and the scn gene by PCR and sequencing. Forty-five (54.9%) milk samples were contaminated by staphylococci and 45 isolates were recovered: 10 Staph. aureus (12.2% of total samples) and 35 CNS (42.7%). Resistance to penicillin (blaZ), tetracycline (tetL/tetK), and erythromycin (ermB/msrA/ermC) were the most common phenotypes (genotypes). Three CNS were methicillin-resistant and all were mecA-positive. The Staph. aureus isolates were ascribed to the following lineages [spa type/sequence type/associated clonal complex (number of isolates)]: t267/ST479/CC479 (n = 6), t1510/ST5651/CC45 (n = 1), t359/ST97/CC97/ (n = 1), t346/ST15/CC15 (n = 1), and t044/ST80 (n = 1). The mecA gene was detected in the cefoxitin-susceptible t044/ST80 isolate and co-harbored the lukF/lukS-PV and scn genes. The detection of mecA-PVL-positive Staph. aureus, methicillin-resistant CNS, and multidrug-resistant staphylococcal species indicates a potentially serious health issue and reveals that unpasteurized milk sold in Djelfa city could be a potential vehicle for pathogenic and antimicrobial-resistant staphylococci.

Detection, molecular characterization, and antibiogram of multi-drug resistant and methicillin-resistant Staphylococcus aureus (MRSA) isolated from pets and pet owners in Malaysia

BACKGROUND

The emergence of multidrug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Staphylococcus aureus (MDRSA) in animals and humans with continuous contact are a great zoonotic concern.

AIMS

This cross-sectional study was performed to investigate the carriage rate, genotypic characteristics, and to determine the antibiogram of S. aureus isolated from pets and pet owners in Malaysia.

METHODS

Nasal and oral swab samples from 40 cats, 30 dogs, and 70 pet owners were collected through convenient sampling. Presumptive colonies on mannitol salt agar were subjected to biochemical identification. S. aureus and MRSA were confirmed by PCR detection of nuc and mecA genes, respectively. Molecular profiles for antimicrobial resistance and virulence genes in S. aureus were also determined. The antibiogram was carried out via Kirby-Bauer test using 18 antibiotics.

RESULTS

17.5% of cats, 20% of dogs, and 27% of pet owners were S. aureus positive. MRSA was also detected in dogs, and pet owners. S. aureus isolates displayed high resistance against penicillin (72.7%), and amoxicillin/clavulanate (66.7%). 39.4% of S. aureus isolates showed multidrug-resistance traits, phenotypically. Molecular characterization of S. aureus revealed the presence of mecA, tetk, tetL, ermA, ermB, ermC, msrA, scn, chp, sak, sep, and sea genes.

CONCLUSION

This study showed the emergence of MRSA and MDRSA in pets and pet owners in Malaysia. The antibiogram findings showed resistance of S. aureus to multiple antibiotics. Furthermore, molecular analysis of immune evasion cluster (IEC) strongly suggests the spread of animal-adapted S. aureus lineages among pets and pet owners.

Molecular investigations on a chimeric strain of Staphylococcus aureus sequence type 80

A PVL-positive, methicillin-susceptible Staphylococcus aureus was cultured from pus from cervical lymphadenitis of a patient of East-African origin. Microarray hybridisation assigned the isolate to clonal complex (CC) 80 but revealed unusual features, including the presence of the ORF-CM14 enterotoxin homologue and of an ACME-III element as well as the absence of etD and edinB. The isolate was subjected to both, Illumina and Nanopore sequencing allowing characterisation of deviating regions within the strain´s genome. Atypical features of this strain were attributable to the presence of two genomic regions that originated from other S. aureus lineages and that comprised, respectively, 3% and 1.4% of the genome. One deviating region extended from walJ to sirB. It comprised ORF-CM14 and the ACME-III element. A homologous but larger fragment was also found in an atypical S. aureus CC1/ST567 strain whose lineage might have served as donor of this genomic region. This region itself is a chimera comprising fragments from CC1 as well as fragments of unknown origin. The other deviating region comprised the region from htsB to ecfA2, i.e., another 3% of the genome. It was very similar to CC1 sequences. Either this suggests an incorporation of CC1 DNA into the study strain, or alternatively a recombination event affecting “canonical” CC80. Thus, the study strain bears witness of several recombination events affecting supposedly core genomic genes. Although the exact mechanism is not yet clear, such chimerism seems to be an additional pathway in the evolution of S. aureus. This could facilitate also a transmission of virulence and resistance factors and therefore offer an additional evolutionary advantage.

Molecular Detection of Panton Valentine Leukocidin Toxin in Clinical Isolates of Staphylococcus aureus from Kiambu County, Kenya

Panton-Valentine leukocidin gene is produced by Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus isolates as a pore-forming toxin is largely responsible for skin and soft tissue illnesses. MRSA produces PVL toxins through lukS and lukF proteins causing tissue necrosis by damaging membrane of the defense cells. Presence of PVL toxin was tested from the 54 S. aureus clinical isolates obtained from Thika and Kiambu Level 5 Hospitals, in Kiambu County, Kenya, by Geno Type® MRSA assay (Hain Life Science, Nehren, Germany). DNA was isolated from freshly harvested bacterial cultures by spin column using Geno Type DNA isolation kit. The detection of PVL toxins was performed by amplification of genomic DNA and by reverse hybridization that identifies PVL genes using Geno Type MRSA kit. Out of 138 samples that were collected from patients in Kiambu County, 54 S. aureus isolates were obtained, of which 14 (25.9%; 95% CI = 11.9-38.9) samples had PVL toxins. The isolates that were obtained from the female patients had a higher PVL toxin prevalence of 35.7%, while the isolates collected from the male patients had a lower prevalence of 15.4% (P = 0.09). The pediatrics department had the highest PVL gene prevalence compared to outpatient department and surgical units (P = 0.08). However, the age groups of patients and the hospital attended by patients showed no significant difference in terms of PVL gene prevalence (P = 0.26). Therefore, the patients' gender and hospital units were not significantly associated with PVL gene prevalence (P = 0.08). This study shows that PVL positive isolates occur in the sampled hospitals in the county and female as well as children must be taken into consideration among patients with wound infections when isolating S. aureus.

Characterization of methicillin-resistant Staphylococcus aureus through genomics approach

In the present study, a total of 35 S. aureus isolates collected from two different geographical locations viz., Germany and Hungary were tested for their methicillin-resistant phenotype which revealed a high incidence of methicillin-resistant S. aureus. The quantitative test for biofilm production revealed that 73.3% of isolates were biofilm producers. The isolates were further characterized using a set of biochemical and genotypic methods such as amplification and analysis of S. aureus species-specific sequence and mecA gene. The 33 mecA positive isolates were then characterized by the amplification of SCCmec and pvl toxin genes. Further, based on the biofilm-forming phenotype, 15 isolates were selected and characterized through PCR–RFLP of coa gene, polymorphism of spa gene and amplification of biofilm-associated genes. The dendrogram prepared from the results of both biochemical and genotypic analyses of the 15 isolates showed that except for the isolates SA G5 and SA H29, the rest of the isolates grouped themselves according to their locations. Thus, the two isolates were selected for further characterization through whole-genome sequencing. Comparative genome analysis revealed that SA G5 and SA H29 have 97.20% ANI values with 2344 gene clusters (core-genome) of which 16 genes were related to antibiotic resistance genes and 57 genes encode virulence factors. The highest numbers of singleton genes were found in SA H29 that encodes proteins for virulence, resistance, mobile elements, and lanthionine biosynthesis. The high-resolution phylogenetic trees generated based on shared proteins and SNPs revealed a clear difference between the two strains and can be useful in distinguishing closely related genomes. The present study demonstrated that the whole-genome sequence analysis technique is required to get a better insight into the MRSA strains which would be helpful in improving diagnostic investigations in real-time to improve patient care.

Two Cases of Intrafamilial Transmission of Community-Acquired Methicillin-Resistant Staphylococcus aureus Producing Both PVL and TSST-1 Causing Fatal Necrotizing Pneumonia and Sepsis

Introduction

Staphylococcus aureus produces numerous toxins, such as toxic shock syndrome toxin 1 (TSST-1) and Panton–Valentine leukocidin (PVL). We isolated community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains producing both TSST-1 and PVL isolated from severe necrotizing pneumonia cases in a Nepali family. Detection of these CA-MRSA strains is rare in the world, and infection with these strains can take a rapidly progressive and lethal course. In this study, we traced the clinical course of this case and conducted a genetic analysis of the isolated strains.

Case Report

We described 2 familial cases (a 20-year-old male and 61-year-old female) of severe necrotizing pneumonia caused by CA-MRSA with the TSST-1 and PVL genes. A 20-year-old Nepalese male was admitted to our hospital after a 3-day history of high fever and coughing. Despite resuscitation efforts, he died of multiple organ failure. A 61-year-old Nepalese female was admitted to our hospital with a complaint of high fever and dyspnea for 1 day. She was the grandmother of the male subject and mostly stayed at his residence in Japan. We administered intravenous antibiotics, including anti-MRSA antibiotics, and she improved in 2 weeks. The sequence type of the isolates was ST22/SCCmec type IVa, and the spa type was t005. The virulence genes detected were as follows: PVL gene (lukSF-pv), TSST-1 gene (tst-1), sec, seg, sei, sel, sem, sen, seo, and seu. ST22 was not the dominant CA-MRSA clone type in Japan. Some of the reports demonstrated that PVL-/TSST-1-positive ST22-MRSA strains are prevalent in Nepal. Therefore, the MRSA strains were thought to be acquired from Nepal.

Conclusion

These cases highlight the emergence of TSST-1- and PVL-positive CA-MRSA infection and its association with life-threatening community-acquired necrotizing pneumonia. Clinicians should note the possibility of introducing MRSA strains from abroad and be aware of this illness to initiate appropriate treatment.

Nusbiarylins Inhibit Transcription and Target Virulence Factors in Bacterial Pathogen Staphylococcus aureus

The emergence of multidrug resistance in the clinically significant pathogen Staphylococcus aureus is a global health burden, compounded by a diminishing drug development pipeline, and a lack of approved novel antimicrobials. Our previously reported first-in-class bacterial transcription inhibitors “nusbiarylins” presented a promising prospect towards the discovery of novel antimicrobial agents with a novel mechanism. Here we investigated and characterised the lead nusbiarylin compound, MC4, and several of its chemical derivatives in both methicillin-resistant S. aureus (MRSA) and the S. aureus type strains, demonstrating their capacity for the arrest of growth and cellular respiration, impairment of RNA and intracellular protein levels at subinhibitory concentrations. In some instances, derivatives of MC4 were also shown to attenuate the production of staphylococcal virulence factors in vitro, such as the exoproteins α-toxin and Panton–Valentine Leukocidin (PVL). Trends observed from quantitative PCR assays suggested that nusbiarylins elicited these effects possibly by acting via but not limited to the modulation of global regulatory pathways, such as the agr regulon, which coordinates the expression of S. aureus genes associated with virulence. Our findings encourage the continued development of more potent compounds within this novel family of bacterial transcription inhibitors.

Prospective genomic surveillance of methicillin-resistant Staphylococcus aureus (MRSA) associated with bloodstream infection, England, 1 October 2012 to 30 September 2013

BackgroundMandatory reporting of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) has occurred in England for over 15years. Epidemiological information is recorded, but routine collection of isolates for characterisation has not been routinely undertaken. Ongoing developments in whole-genome sequencing (WGS) have demonstrated its value in outbreak investigations and for determining the spread of antimicrobial resistance and bacterial population structure. Benefits of adding genomics to routine epidemiological MRSA surveillance are unknown.AimTo determine feasibility and potential utility of adding genomics to epidemiological surveillance of MRSA.MethodsWe conducted an epidemiological and genomic survey of MRSA BSI in England over a 1-year period (1 October 2012--30 September 2013).ResultsDuring the study period, 903 cases of MRSA BSI were reported; 425 isolates were available for sequencing of which, 276 (65%) were clonal complex (CC) 22. Addition of 64 MRSA genomes from published outbreak investigations showed that the study genomes could provide context for outbreak isolates and supported cluster identification. Comparison to other MRSA genome collections demonstrated variation in clonal diversity achieved through different sampling strategies and identified potentially high-risk clones e.g. USA300 and local expansion of CC5 MRSA in South West England.ConclusionsWe demonstrate the potential utility of combined epidemiological and genomic MRSA BSI surveillance to determine the national population structure of MRSA, contextualise previous MRSA outbreaks, and detect potentially high-risk lineages. These findings support the integration of epidemiological and genomic surveillance for MRSA BSI as a step towards a comprehensive surveillance programme in England.

Molecular Characterization and Pathogenicity of Staphylococcus aureus Isolated from Benin-City, Nigeria

While numerous studies examine the epidemiology and molecular characterization of Staphylococcus aureus in most developed countries, the detailed molecular characterization and molecular epidemiology of S. aureus strains and clones in Africa is lacking. We determined the molecular epidemiology and virulence of 81 non-duplicate isolates of S. aureus from Benin-City, Nigeria, collected during January–July 2016, and compared with global strains. Forty-seven isolates (58.0%) were found to be methicillin-sensitive Staphylococcus aureus (MSSA), while 34 (42.0%) were methicillin-resistant Staphylococcus aureus (MRSA). ST152-MSSA (24.7%) and ST7-MRSA-V (19.8%) were the dominant groups identified, which were not genetically related to global predominant strains, but rather exhibited regional dominance. An interesting finding of the study was the presence of highly related strains in the region, which differed primarily in their methicillin resistance gene carriage, staphylococcal cassette chromosome mec (SCCmec), with 99.4–99.7% relatedness between the genomes of the strains within the MRSA–MSSA pairs. This suggests that the strains within a pair are experiencing gain or loss of SCCmec within local conditions, with evolution continuing to diversify the strains to a small degree. This study represents the most comprehensive genetic and virulence study of S. aureus in Nigeria.

Pediatric Community-Acquired Bone and Joint Staphylococcus Aureus Infections In Europe: Severe Infections are Associated to Panton-Valentine Leucocidin Presence

To analyze host and pathogen factors related to disease severity of community-acquired bone and joint infections in children, a cohort of pediatric patients was prospectively recruited from 13 centers in 7 European countries. A total of 85 children were included, 11 (13%) had a severe infection. Panton-Valentine leukocidin-positive isolates were 17%, and 6% of the isolates were methicillin-resistant Staphylococcus aureus. Multivariate analysis identified Panton-Valentine leukocidin presence (adjusted odds ratio, 12.6; P = 0.01) as the only factor independently associated with severe outcome, regardless of methicillin resistance.

Prevalence of Methicillin-Resistant Staphylococcus aureus and Associated Risk Factors among Patients with Wound Infection at Referral Hospital, Northeast Ethiopia

Background

The spectrums of infections due to methicillin-resistant Staphylococcus aureus are manifold and are associated with worse outcomes. A study on the prevalence of these pathogens and their sensitivity patterns will give updated information which is very helpful for health personnel responsible in the management of patients and timely monitoring of the emergence of resistant bacteria. Hence, the study aimed at assessing the prevalence of methicillin-resistant Staphylococcus aureus and associated factors among patients with wound infection at Dessie Referral Hospital.

Method

A cross-sectional study was conducted among 266 patients at Dessie Referral Hospital from February to May 2016. Wound swab samples were collected aseptically using Levine's technique and transported to Dessie Regional Laboratory by using brain-heart infusion transport media. Isolation of Staphylococcus aureus was done based on cultural and biochemical profiles. Drug susceptibility test was performed using the disc diffusion technique as per the standard and interpreted based on the Clinical and Laboratory Standards Institute guidelines. The data were entered and analyzed by using SPSS version 20.

Result

Staphylococcus isolates from 266 processed wound swabs were 92 (34.58%). Of these, 26 (28.3%) were identified as methicillin-resistant S. aureus and 66 (71.7%) were methicillin-sensitive S. aureus. The overall prevalence of methicillin-resistant S. aureus among the study population was 9.8%. The isolated methicillin-resistant S. aureus showed full resistance to penicillin (100%) followed by erythromycin and ciprofloxacin (16, 61.5%) and cotrimoxazole and gentamicin (14, 53.8%). From the total S. aureus isolates, 20 (21.7%) of them showed multidrug resistance. Of these methicillin-resistant S. aureus, 18 (69.8%) showed high multidrug resistance. Patients who are farmers in occupation (AOR = 6.1, 95% CI (1.086–33.724)), admitted in the hospital (AOR = 3.56, 95% CI (1.429–8.857)), and have low BMI (<18.5) (AOR = 13.89, 95% CI (4.919–39.192)) were among the risk factors significantly associated with wound infection due to methicillin-resistant S. aureus.

Conclusion

All methicillin-resistant S. aureus isolates were 100% resistant to penicillin and showed high multidrug resistance. Therefore, antibiotic susceptibility test should be performed prior to treatment.

Profiles of Staphyloccocus aureus isolated from goat persistent mastitis before and after treatment with enrofloxacin

BACKGROUND

Staphylococcus aureus is one of the main causative agents of mastitis in small ruminants. Antimicrobial use is the major treatment, but there are many flaws linked to resistance, tolerance or persistence. This study aimed to verify changes in resistance, virulence and clonal profiles of S. aureus isolated from persistent mastitis goat milk before and after enrofloxacin treatment.

RESULTS

MIC increased to at least one antimicrobial in S. aureus isolates after enrofloxacin treatment compared to before. The most detected resistance genes before and after treatment were tetK, tetM, and blaZ, with more resistance genes detected after enrofloxacin treatment (p < 0.05). Occasional variations in efflux system gene detection were observed before and after treatment. Nine virulence genes (hla, fnbA, fnbB, eta, etb, sea, sec, seh, and sej) were detected at both times, and between these, the hla and eta genes were detected more in isolates after treatment. All isolates of S. aureus belonged to the same sequence type (ST) 133, except for two S. aureus isolates prior to enrofloxacin treatment which were classified as ST5 and the other as a new one, ST4966. Isolates of S. aureus 4, 8, and 100 from before and after treatment had identical pulse types, while others obtained from other animals before and after treatment were classified into distinct pulse types.

CONCLUSION

There were occasional changes in the studied profiles of S. aureus isolated before and after treatment of animals with enrofloxacin, which may have contributed to the permanence of bacteria in the mammary gland, even when using traditional treatment, resulting in persistent mastitis.

Prevalence, Genetic Diversity, and Temporary Shifts of Inducible Clindamycin Resistance Staphylococcus aureus Clones in Tehran, Iran: A Molecular-Epidemiological Analysis From 2013 to 2018

The prevalence of Staphylococcus aureus as an aggressive pathogen resistant to multiple antibiotics causing nosocomial and community-acquired infections is increasing with limited therapeutic options. Macrolide-lincosamide streptogramin B (MLSB) family of antibiotics represents an important alternative therapy for staphylococcal infections. This study was conducted over a period of five years from August 2013 to July 2018 to investigate the prevalence and molecular epidemiology in Iran of inducible resistance in S. aureus. In the current study, 126 inducible methicillin-resistant S. aureus (MRSA) (n = 106) and methicillin-sensitive S. aureus (MSSA) (n = 20) isolates were characterized by in vitro susceptibility analysis, resistance and virulence encoding gene distribution, phenotypic and genotypic analysis of biofilm formation, prophage typing, S. aureus protein A locus (spa) typing, staphylocoagulase (SC) typing, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing. Of the 126 isolates, 76 (60.3%) were classified as hospital onset, and 50 (39.7%) were classified as community onset (CO). Biofilm formation was observed in 97 strains (77%). A total of 14 sequence types (STs), 26 spa types, 7 coagulase types, 9 prophage types, 3 agr types (no agr IV), and 9 clonal complexes (CCs) were identified in this study. The prevalence of the inducible MLSB (iMLSB) S. aureus increased from 7.5% (25/335) to 21.7% (38/175) during the study period. The iMLSB MRSA isolates were distributed in nine CCs, whereas the MSSA isolates were less diverse, which mainly belonged to CC22 (7.95%) and CC30 (7.95%). High-level mupirocin-resistant strains belonged to ST85-SCCmec IV/t008 (n = 4), ST5-SCCmec IV/t002 (n = 4), ST239-SCCmec III/t631 (n = 2), and ST8-SCCmec IV/t064 (n = 2) clones, whereas low-level mupirocin-resistant strains belonged to ST15-SCCmec IV/t084 (n = 5), ST239-SCCmec III/t860 (n = 3), and ST22-SCCmec IV/t790 (n = 3) clones. All the fusidic acid–resistant iMLSB isolates were MRSA and belonged to ST15-SCCmec IV/t084 (n = 2), ST239-SCCmec III/t030 (n = 2), ST1-SCCmec V/t6811 (n = 1), ST80-SCCmec IV/t044 (n = 1), and ST59-SCCmec IV/t437 (n = 1). The CC22 that was predominant in 2013–2014 (36% of the isolates) had almost disappeared in 2017–2018, being replaced by the CC8, which represented 39.5% of the 2017–2018 isolates. This is the first description of temporal shifts of iMLSB S. aureus isolates in Iran that identifies predominant clones and treatment options for iMLSB S. aureus–related infections.

Methicillin-Resistant Staphylococcus aureus ST80 Clone: A Systematic Review

This review assessed the molecular characterization of the methicillin-resistant Staphylococcus aureus (MRSA)-ST80 clone with an emphasis on its proportion of total MRSA strains isolated, PVL production, spa-typing, antibiotic resistance, and virulence. A systematic review of the literature was conducted on MRSA-ST80 clone published between 1 January 2000 and 31 August 2019. Citations were chosen for a review of the full text if we found evidence that MRSA-ST80 clone was reported in the study. For each isolate, the country of isolation, the sampling period, the source of isolation (the type of infection, nasal swabs, or extra-human), the total number of MRSA strains isolated, number of MRSA-ST80 strains, antibiotic resistance patterns, PVL production, virulence genes, and spa type were recorded. The data from 103 articles were abstracted into an Excel database. Analysis of the data showed that the overall proportion of MRSA-ST80 has been decreasing in many countries in recent years. The majority of MRSA-ST80 were PVL positive with spa-type t044. Only six reports of MRSA-ST80 in extra-human niches were found. This review summarizes the rise of MRSA-ST80 and the evidence that suggests that it could be in decline in many countries.

Psoitis and multiple venous thromboses caused by Panton Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus in a 12-year-old girl: A case report

Panton Valentine Leukocidin (PVL) is one of the many toxins produced by Staphylococcus aureus. In Japan, PVL-positive S. aureus strains are mainly methicillin-resistant S. aureus (MRSA). Data regarding PVL-positive methicillin-sensitive S. aureus (MSSA) are scarce. In this report, we describe a case of severe infection by PVL-positive MSSA. A 12-year-old healthy girl was admitted with high fever and pain in the lower back. Computed tomography revealed a diagnosis of psoitis and multiple venous thromboses. Blood cultures obtained after admission revealed infection with MSSA. Her fever continued despite adequate antibiotic therapy. On the fifth hospitalization day, she developed bladder dysfunction, and an abscess was noted near the third lumbar vertebra. She underwent an emergency operation and recovered. Bacterial analyses revealed that the causative MSSA was a PVL-producing single variant of ST8 (related to USA300clone), of sequence type 2149. PVL is known to cause platelet activation. This case demonstrates the need for detailed analyses of the causative strain of bacteria in cases of S. aureus infection with deep vein thrombosis, even in cases of known MSSA infection.

Outbreak report of investigation and control of an outbreak of Panton-Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus (PVL-MSSA) infection in neonates and mothers

Background

In January 2011, there was an outbreak of Panton-Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus (PVL-MSSA) infection in a neonatal unit (NNU).

We describe the investigation and control of an outbreak of PVL-MSSA infection in neonates. Setting: Neonatal unit in West London.

Methods

We performed descriptive and analytical (case-control study) epidemiological investigations. Microbiological investigations including screening of MSSA isolates by PCR for the presence of the luk-PV, mecA and mecC genes and comparison of isolate with Pulsed field gel electrophoresis (PFGE). Control measures were also introduced.

Results

Sixteen babies were infected/colonised with the outbreak strain. Of these, one baby developed blood stream infection, 12 developed skin pustules and four babies were colonised.

Four mothers developed breast abscesses. Eighty-seven babies in the unit were screened and 16 were found to have same PVL-MSSA strain (spa type t005, belonging to MLST clonal complex 22). Multivariate analysis showed gestational age was significantly lower in cases compared to controls (mean gestational age: 31.7 weeks v 35.6 weeks; P = 0.006). Length of stay was significantly greater for cases, with a median of 25 days, compared to only 6 days for controls (P = 0.01). Most (88%) cases were born through caesarean section, compared to less than half of controls. (P = 0.002).

No healthcare worker carriers and environmental source was identified. The outbreak was controlled by stopping new admissions to unit and reinforcing infection control precautions. The outbreak lasted for seven weeks. No further cases were reported in the following year.

Conclusions

Infection control teams have to be vigilant for rising prevalence of particular S. aureus clones in their local community as they may cause outbreaks in vulnerable populations in healthcare settings such as NNUs.

Retrospective study of pneumonia due to Panton-Valentine leukocidin-producing Staphylococcus aureus in Reunion

OBJECTIVE

Panton-Valentine leukocidin-producing Staphylococcus aureus necrotizing pneumonia is an unusual cause of community-acquired pneumonia, although associated with a high case fatality. This infection mainly affects young individuals, without any history, and is most often preceded by flu-like symptoms.

METHOD

We focused on patients presenting with Staphylococcus aureus necrotizing pneumonia in Reunion (Indian Ocean) admitted to the emergency department. We performed a retrospective study based on data collected from laboratory registers and medical files of patients presenting with Staphylococcus aureus necrotizing pneumonia in Reunion between December 2014 and December 2017.

RESULTS

A total of 16 patients were recruited for this study, with a median age of 40.5 years. More than half of patients had previously been admitted to the emergency department for acute respiratory distress syndrome or severe sepsis. Fourteen patients were admitted to the intensive care unit and six patients died (five premature deaths).

CONCLUSION

Physicians should be aware of this infection during the flu season and quickly adapt the specific antibiotic treatment, including a drug inhibiting toxin production. As methicillin-resistant Staphylococcus aureus is very rarely observed in Reunion, physicians can still adapt the empirical treatment, without glycopeptides.

Methicillin-Resistant Staphylococcus aureus: Molecular Characterization, Evolution, and Epidemiology

Staphylococcus aureus, a major human pathogen, has a collection of virulence factors and the ability to acquire resistance to most antibiotics. This ability is further augmented by constant emergence of new clones, making S. aureus a "superbug." Clinical use of methicillin has led to the appearance of methicillin-resistant S. aureus (MRSA). The past few decades have witnessed the existence of new MRSA clones. Unlike traditional MRSA residing in hospitals, the new clones can invade community settings and infect people without predisposing risk factors. This evolution continues with the buildup of the MRSA reservoir in companion and food animals. This review focuses on imparting a better understanding of MRSA evolution and its molecular characterization and epidemiology. We first describe the origin of MRSA, with emphasis on the diverse nature of staphylococcal cassette chromosome mec (SCCmec). mecA and its new homologues (mecB, mecC, and mecD), SCCmec types (13 SCCmec types have been discovered to date), and their classification criteria are discussed. The review then describes various typing methods applied to study the molecular epidemiology and evolutionary nature of MRSA. Starting with the historical methods and continuing to the advanced whole-genome approaches, typing of collections of MRSA has shed light on the origin, spread, and evolutionary pathways of MRSA clones.

Emerging of antimicrobial resistance in staphylococci isolated from clinical and food samples in Algeria

Objective

The antimicrobial resistance of staphylococci rose worldwide. In total, 96 Staphylococcus isolates from food and clinical samples were collected from two provinces in Algeria. The antimicrobial susceptibility testing was performed and resistance-associated genes were detected.

Results

Fifty-one strains were isolated from food samples and differentiated into 33 Staphylococcus aureus and 18 coagulase-negative staphylococci. Forty-five staphylococci were collected from hospital and community-acquired infection cases. All S. aureus isolated from food were resistant to penicillin and 45.5% were resistant to tetracycline. The resistance rates of 45 clinical Staphylococcus isolates were 86.7%, 48.9%, 37.8% and 20.0% to penicillin, tetracycline, erythromycin and kanamycin, respectively. Nine isolates were confirmed as MRSA from food and clinical isolates. One S. aureus originated from food was confirmed as vancomycin-resistant. Multidrug-resistance was observed among 25.5% and 53.3% of food and clinical staphylococci, respectively. The tetM/K, blaZ, aacA-aphD, ermC and mecA genes were detected in food and clinical isolates. ermA gene was not found. This study provided insight into the status of antimicrobial resistance of staphylococci isolated from food and clinical samples in Algeria. Further investigations and surveillance programmes are mandatory.

Fulminant Staphylococcal Infections

Fulminant staphylococcal infection indicates an explosive, intense, and severe infection occurring in a patient whose previous condition and antecedent would never have caused any anticipation of life-threatening development. This includes necrotizing pneumonia, necrotizing fasciitis, and to some extent toxic shock syndrome and infective endocarditis. In the three former diseases, toxin production plays a major role whereas in the latter (fulminant presentation of infective endocarditis), association with any particular toxinic profile has never been demonstrated. This article reviews the clinical, pathophysiological, and therapeutic aspects of these diseases.

Prevalence of Panton-Valentine Leukocidin Gene among Community Acquired Staphylococcus aureus: A Real-Time PCR Study

Panton-Valentine leukocidin (luk-pv) is a cytotoxin that causes leukocyte destruction and tissue necrosis. The aim of this study was to determine the prevalence of the pv1, mecA, and nuc genes in Staphylococcus aureus isolates obtained from anterior nares and superficial infection sites of skin in a slum population of West Bengal, India. Expression level of pv1 gene was also analysed. Twenty-two S. aureus strains were isolated, and phenotype and genotype specific examinations for S. aureus isolates were carried out. Molecular identification was done by PCR using species-specific 16S rRNA primer pairs and finally 22 isolates were found to be positive as S. aureus. The antibiotic responsiveness of all these isolates and the minimum inhibitory concentration (MIC) of MRSA isolates were determined using the broth dilution method with vancomycin. Antibiogram analysis of isolated S. aureus strains with respect to different antimicrobial agents revealed antibiotic resistance ranging from 27 to 91%. The results of MIC for vancomycin showed 95% of strains to be VSSA and 5% to be VISA. 68% isolates were resistant to methicillin. All the isolates were subjected to detection of pv1, mecA, and nuc genes, and 9%, 68%, and 27% were found to harbour pvl, mecA, and nuc genes, respectively. All the MRSA strains produced high to moderate levels of biofilm. pvl gene expression was carried out in vitro by Real-Time PCR. The low ∆Ct value (0.493) was indicative of high expression of pvl in one S. aureus strain. Thus, detection of pvl gene in community acquired S. aureus indicates the emergence of pathogenic S. aureus in community setup in the studied region. The existing exploration is extremely imperative and informative for the high level multi-drug resistant S. aureus infections inclusive of MRSA.

Molecular Epidemiological Characterization of Methicillin-Susceptible and -Resistant Staphylococcus aureus Isolated from Skin and Soft Tissue Infections in Bangladesh

Genetic background and molecular characteristics of Staphylococcus aureus collected from patients with skin and soft tissue infections were studied in the North-Central region of Bangladesh from 2015 to 2016. Among 430 clinical isolates, methicillin-resistant S. aureus (MRSA) accounted for 31% having SCCmec type IV (73%) and V (14%), and belonged mostly to coagulase (coa) genotypes IIa, IIIa, IVb, and XIa, while dominant coa type in methicillin-susceptible S. aureus (MSSA) was IIIa, followed by Va, IIa, and VIa. Panton-Valentine Leukocidin genes (pvl) were detected at higher rate in MSSA (54%) than in MRSA (24%). Based on multilocus sequence typing, pvl-positive MRSA isolates were classified into clonal complex 88 (CC88) (ST88, ST2884, ST4345), CC6 (ST6, ST4350), and CC1 (ST1, ST772), while pvl-negative MRSA into CC5, CC22, CC80, CC121, and CC672. The pvl-negative ST80 MRSA isolates had SCCmec-IVa (agr-III/coa-XIc, etd/edinB-positive, fusB-negative), indicating that they belong to the novel CC80 clade related to the European community-acquired MRSA clone. Among MSSA, genotypes ST121/spa-t645/coa-Va and ST2884 (CC88)/spa-t2393/coa-IIIa were identified in both pvl-positive and negative isolates, and all the ST772 isolates harbored pvl. All the ST121 isolates had a variant of elastin-binding protein gene (ebpS-v) with internal 180-nucleotide deletion. The present study suggested that CC88 (ST88, ST2884) and ST772 are the putative dominant lineages of pvl-positive MRSA/MSSA, while novel CC80 clade is one of the main pvl-negative MRSA lineages distributed endemically in Bangladesh.

Characterization of Panton-Valentine leukocidin-positive Staphylococcus aureus from skin and soft tissue infections and wounds in Nigeria: a cross-sectional study

Background:Staphylococcus aureus is a significant pathogen implicated in numerous nosocomial and community-acquired infections. The Panton-Valentine leukocidin (PVL) can be associated with severe necrotizing diseases such as pneumonia, skin and soft tissue infection (SSTI).  Methods: In total, 96 S. aureus isolates were obtained from patients presenting with wounds (n=48) and soft tissue infections (SSTIs, n=48). These were characterized based on their antimicrobial susceptibility profile, the possession of virulence genes (e.g. capsular type, PVL), accessory gene regulator ( agr) type, and the staphylococcal protein A ( spa) type. The production of the PVL protein was assessed by western blotting. Results: All isolates were susceptible to methicillin. The resistance was highest to penicillin (97.9%), followed by trimethoprim/sulfamethoxazole (85.4%) and tetracycline (10.4%). The PVL gene was found in 83.3% of isolates from SSTIs and in 79.2% of isolates from wound. Of these, 53 (68%) produced PVL as assessed by western blotting. The most prevalent spa type was the t084 (78.1%, n=75) and, majority of the isolates carried  agr2 (82.3%, n=79). Conclusions: Prevalence of antibiotic resistant PVL-positive methicillin susceptible S. aureus strains has severe implications on PVL mediated infections.

Subscapular Abscess Caused by Panton-Valentine Leukocidin-Positive Staphylococcus aureus: An Atypical Presentation

Subscapular abscess is an uncommon condition which requires early recognition followed by prompt surgical intervention. We present a case of spontaneous subscapular abscess following blunt trauma to the shoulder in a patient with a history of recurrent superficial soft tissue infections, in which Panton-Valentine leukocidin-producing S. aureus was identified as the infectious agent. This strain due to its virulence can lead to fatal infections in otherwise healthy individuals; therefore, a high index of suspicion is needed to investigate with an MRI to rule out abscess formation in a patient with acute shoulder girdle pain and negative joint aspirate. Urgent surgical intervention and targeted antimicrobial therapy against PVL-positive S. aureus in accordance with microbiologist yield good outcomes.

Phenotypic and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus Clones Carrying the Panton-Valentine Leukocidin Genes Disseminating in Iranian Hospitals

The spread of Panton-Valentine leukocidin (PVL)-carrying Staphylococcus aureus strains in both hospital and the community is a significant worldwide problem. The aim of the study was to investigate the clonal dissemination pattern of PVL-producing S. aureus strains isolated from hospitalized patients in Tehran, Iran. In this cross-sectional study, 70 PVL-carrying S. aureus strains were recovered from 240 clinical specimens and characterized by antibiotic susceptibility testing, agr typing, SCCmec typing, spa typing, multilocus sequence typing, and virulence and adhesion gene profiling. All the PVL-carrying S. aureus strains were confirmed as methicillin-resistant S. aureus (MRSA) and recovered from wounds (48.6%), blood (25.7%), exudate/pus (11.4%), sputum (8.6%), and body fluid (5.7%) samples. Among the 70 PVL-carrying S. aureus strains tested, 38 (54.3%) were positive for ant (4')-Ia gene, 27 (38.6%) for aac (6')-Ie/aph (2″), 13 (18.6%) for msr(A), 13 (18.6%) for erm(C), 13 (18.6%) for tet(M), 11 (15.7%) for erm(A), 10(14.3%) for msr(B), 9 (12.9%) for aph (3')-IIIa, 5 (7.1%) for mupA, and 2 (2.9%) for erm(B) genes. Five clonal complexes (CC) and nine different clones were detected in this study. The most frequent CC was CC22 (ST22) (42.8%) followed by CC30 (ST30) (21.5%), CC8 (ST8) (17.2%), CC1 (ST772) (11.4%), and CC80 (ST80) (7.1%). In this study, ST22-SCCmec IV/t852 was the predominant PVL-positive MRSA clone (20%), followed by ST8-SCCmec IV/t008 (17.2%), ST30-SCCmec IV/t019 (12.9%), ST22-SCCmec IV/t790 (11.4%), ST22-SCCmec IV/t005 (11.4%), ST30-SCCmec IV/t021 (8.6%), ST80-SCCmec IV/t044 (7.1%), ST772-SCCmec V/t657 (7.1%), and ST772-SCCmec V/t10795 (4.3%). Diversity in clonal types of PVL-carrying MRSA strains in our study supports the need to perform a systematic surveillance of PVL-positive MRSA strains.