Panton-Valentine Leukocidin Research Articles

Staphylococcus aureus isolates from Eurasian Beavers (Castor fiber) carry a novel phage-borne bicomponent leukocidin related to the Panton-Valentine leukocidin

Staphylococcus aureus can be a harmless coloniser, but it can also cause severe infections in humans, livestock and wildlife. Regarding the latter, only few studies have been performed and knowledge on virulence factors is insufficient. The aim of the present study was to study S. aureus isolates from deceased wild beavers (Castor fiber). Seventeen isolates from eleven beavers, found in Germany and Austria, were investigated. Antimicrobial and biocide susceptibility tests were performed. Isolates were characterised using S. aureus-specific DNA microarrays, spa typing and whole-genome sequencing. From two isolates, prophages were induced by mitomycin C and studied by transmission electron microscopy. Four isolates belonged to clonal complex (CC) 8, CC12, and CC398. Twelve isolates belonged to CC1956 and one isolate was CC49. The CC49 and CC1956 isolates carried distinct lukF/S genes related to the Panton-Valentine leukocidin (PVL) from human isolates of S. aureus. These genes were located on related, but not identical, Siphovirus prophages. The beavers, from which those isolates originated, suffered from abscesses, purulent organ lesions and necrotising pneumonia, i.e., clinical manifestations resembling symptoms of severe PVL-associated disease in humans. It might thus be assumed that the “Beaver Leukocidin (BVL, lukF/S-BV)”-positive strains are beaver-specific pathogens, and further studies on their clinical role as well as on a possible transmissibility to other species, including humans, are warranted.

Clinical Features and Molecular Characteristics of Methicillin-Susceptible Staphylococcus aureus Ocular Infection in Taiwan.

This study analyzed the clinical features and molecular characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) ocular infections in Taiwan and compared them between community-associated (CA) and health-care-associated (HA) infections. We collected S. aureus ocular isolates from patients at Chang Gung Memorial Hospital between 2010 and 2017. The infections were classified as CA or HA using epidemiological criteria, and the isolates were molecularly characterized using pulsed-field gel electrophoresis, multilocus sequence typing, and Panton-Valentine leukocidin (PVL) gene detection. Antibiotic susceptibility was evaluated using disk diffusion and an E test. A total of 104 MSSA ocular isolates were identified; 46 (44.2%) were CA-MSSA and 58 (55.8%) were HA-MSSA. Compared with HA-MSSA strains, CA-MSSA strains caused a significantly higher rate of keratitis, but a lower rate of conjunctivitis. We identified 14 pulsotypes. ST 7/pulsotype BA was frequently identified in both CA-MSSA (28.3%) and HA-MSSA (37.9%) cases. PVL genes were identified in seven isolates (6.7%). Both CA-MSSA and HA-MSSA isolates were highly susceptible to vancomycin, teicoplanin, tigecycline, sulfamethoxazole–trimethoprim, and fluoroquinolones. The most common ocular manifestations were keratitis and conjunctivitis for CA-MSSA and HA-MSSA, respectively. The MSSA ocular isolates had diverse molecular characteristics; no specific genotype differentiated CA-MSSA from HA-MSSA. Both strains exhibited similar antibiotic susceptibility.

Prevalence of Methicillin-Resistant Staphylococcus Species Among Filarial Lymphedema Patients in Ahanta West District of Ghana

BackgroundFilarial pathologies such as lymphedema may be associated with complications such as chronic non-healing wounds. Nonetheless, the role of bacterial population colonizing the lymphedematous legs has been posited to worsen the conditions of those living with the infection. These bacteria are usually composed of staphylococcal species partly because they are commensals. Thus, this present study sought to type the methicillin-resistant Staphylococcus aureus (MRSA) prevalence among individuals presenting with filarial lymphedema, particularly as MRSA tends to affect treatments options.MethodsWe recruited individuals (n = 321) with stages I–VII of lymphedema in a cross-sectional study in the Ahanta West district of the Western Region of Ghana. Swabs from lymphedematous limb ulcers, pus, and cutaneous surfaces were cultured using standard culture-based techniques. The culture isolates were later identified using Matrix-assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry.ResultsA total of 192 Staphylococci species were isolated, with an overall prevalence of 39.7% (95% CI: 35%–44%; N = 483). S. hominis was the most prevalent species (23.95%), followed by S. haemolyticus (20.83%), S. epidermidis (15.10%), S. aureus (10.41%), and S. saprophyticus (9.32%). The remaining 20.34% were distributed among S. wanneri, S. sciuri, S. pasteuri, S. xylosus, S. simulans, S. cohnii, S. caprae, S. lugdunensis, and S. capitis. MRSA, containing mecA gene, was detected in 21 out of 31 Staphylococci isolates tested, with an overall prevalence of 68% (95% CI: 51%–84%). In addition, a virulent gene, Panton–Valentine leukocidin (PVL), which is usually associated with S. aureus, was detected in 20/31 (64.5%) S. aureus in the study.ConclusionThese results suggest that MRSA species may pose a challenge to the treatment of filarial lymphedema with antibiotics particularly, as doxycycline is currently being piloted in some endemic areas to treat the infection. Thus, intensive antimicrobial resistance surveillance should be conducted in endemic areas by health authorities to forestall the dilemma of multidrug resistance not only against lymphatic filariasis (LF) infection but other diseases.

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

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

Draft Genome Sequences of Eight Community-Associated Methicillin-Resistant Staphylococcus aureus Strains

ABSTRACTHere, we report the draft genome sequences of eight community-associated methicillin-resistant Staphylococcus aureus strains that were resistant to cefoxitin, ampicillin, and erythromycin. Three isolates, i.e., CAR1, CAR2, and CAR8, were sequence type 8 (ST8) with staphylococcal cassette chromosome mec (SCCmec) type IVa and were Panton-Valentine leukocidin (PVL) positive, which has been known as a predominant clone in the United States.

Characterisation and Molecular Analysis of an Unusual Chimeric Methicillin Resistant Staphylococcus Aureus Strain and its Bacteriophages.

In the context of microarray-based epidemiological typing of the clonal organism Staphylococcus aureus/MRSA, a strain was identified that did not belong to known clonal complexes. The molecular analysis by microarray-based typing yielded signals suggesting that it was a mosaic or hybrid strain of two lineages. To verify this result, the isolate was sequenced with both, short-read Illumina and long-read Nanopore technologies and analysed in detail. This supported the hypothesis that the genome of this strain, ST6610-MRSA-IVg comprised of segments originating from two different clonal complexes (CC). While the backbone of the strain’s genome, i.e., roughly 2 megabases, belongs to CC8, a continuous insert of 894 kb (approx. 30% of the genome) originated from CC140. Beside core genomic markers in the normal succession and orientation, this insert also included the mecA gene, coding for PbP2a and causing methicillin resistance, localised on an SCCmec IVg element. This particular SCCmec type was also previously observed in CC140 MRSA from African countries. A second conspicuous observation was the presence of the trimethoprim resistance gene dfrG within on a prophage that occupied an attachment site normally used by Panton-Valentine Leucocidin phages. This observation could indicate a role of large-scale chromosomal recombination in the evolution of S. aureus as well as a role of phages in the dissemination of antibiotic resistance genes.

Methicillin-resistant Staphylococcus aureus transmission and hospital-acquired bacteremia in a neonatal intensive care unit in Greece

BackgroundStaphylococcus aureus is a common pathogen causing hospital acquired infections (HAIs) in neonates. In this study, the epidemiology of methicillin-resistant S. aureus (MRSA) colonization and infections in a 30-bed, level III university-affiliated neonatal intensive care unit (NICU) located in a children's hospital was retrospectively investigated for the period 2014–2018. MethodsGenes encoding Panton-Valentine Leukocidin (lukS/lukF-PV, PVL), toxic shock syndrome toxin (tst), exfoliative toxins (eta, etb), and the resistance genes mecA, mecC and fusB, were defined in 46 representative strains by PCRs. Relatedness of strains was assessed by MLST. ResultsOf 1538 neonates, 77 (5%) had a positive culture for MRSA (23/77 were NICU-acquired and 54/77 imported cases). Four MRSA bacteremias occurred. Most isolates were multi-resistant. One major clone was identified, ST225, among 40 tested neonatal strains (23/40, 58%). Of these, 14/23 were imported from the same maternity hospital (MH). Another clone, ST217, was predominant (4/6) among health care workers (HCWs), found colonized. Four isolates classified as ST80 were PVL-positive. Additional four strains carried tst (10%), belonging to ST30 and ST225 (two strains each), and two etb. The implicated MH was notified for the problem, decolonization treatment was successfully performed in HCWs and neonates. Strengthening of infection control measures with emphasis on hand hygiene was applied. ConclusionsUncovering reservoirs for on-going MRSA transmission in NICUs has proved challenging. Well known nosocomial MRSA clones are being constantly introduced and transmitted via MHs and HCWs. Effective infection prevention and control requires constant vigilance.

Evaluation of virulence potential of methicillin-sensitive and methicillin-resistant Staphylococcus aureus isolates from a German refugee cohort

BackgroundCommunity-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) seem to be highly transmissible, often infect otherwise healthy humans and frequently occur in hospital outbreaks. MethodsRefugees, living in accommodations in Germany were screened for nasal carriage of S. aureus. The isolates were investigated regarding resistance and virulence, phenotypically and by whole genome data analysis. Results5.6% (9/161) of the refugees are carriers of S. aureus. 2.5% (4/161) are MRSA carriers. Among the refugees, spa-types t021, t084, t304, t991 and t4983 were detected, as well as the new spa-types t18794 and t18795. t304 and t991 are assumed to be local spa-types from the middle east. The isolates are less resistant and marginal biofilm formers. Each isolate has a remarkable set of virulence genes, although genes, encoding for proteins strongly associated with invasive S. aureus infections, like Panton-Valentine leucocidin, were not detected. ConclusionThe detection of strains from the middle east, supports the assumption that strains co-travel with the refugees and persist despite a transition of the host's living conditions. Whole genome data analysis does not permit to finally evaluate a germ's virulence. Nevertheless, an impression of the virulence potential of the strains, regarding skills in colonization, resistance, immune evasion, and host cell damaging can be pictured.

Some virulence genes of Staphylococcus aureus isolated from infected vascular accesses in hemodialysis patients at Assiut University Hospitals

We aimed in this work to detect bacterial pathogens causing infection of the vascular accesses in hemodialysis patients and demonstration of important genes responsible for virulence and biofilm formation in Staphylococcus aureus isolates namely; spa, mecA, PVL, γ-hemolysin, and icaA genes. The study was conducted from March 2018 to September 2020 and included 90 patients with infected hemodialysis accesses. Blood samples were collected for blood culture. Distal catheter end was cut and placed in brain heart infusion broth. Total bacterial isolates were 234. Samples were identified by conventional bacteriological methods. Virulent genes In Staph. aureus were detected by PCR. Staph. aureus was the most common isolated microorganism. Fifty (96.25%) of the 52 Staph. aureus isolates were mecA gene positive. The most common spa genotype was at S3 followed by S2. Forty of 52 (76.90 %) Staph. aureus isolates were icaA positive. Only 2(3.85%) Staph. aureus isolates were gamma-hemolysin positive. All 52 isolates of Staph. aureus were negative for Panton-Valentine leukocidin gene.

Staphylococcus aureus Isolated from the Oral Cavity: Phage Susceptibility in Relation to Antibiotic Resistance.

Nowadays, research on bacteriophage therapy and its potential use in combination with antibiotics has been gaining momentum. One hundred and ten oral Staphylococcus aureus isolates were phage-typed and their antibiotic resistance was determined by standard and molecular methods. The prevalence of MSSA and MRSA strains was 89.1% and 10.9%, respectively. Nearly all (91.8%) analyzed isolates, whether MSSA or MRSA, were susceptible to the phages used from the international set. The highest lytic activity showed phages 79 and 52 A from lytic group I. The predominant phage groups were mixed, the I+III group and a mixed group containing phages from at least three various lytic groups. S. aureus strains sensitive to phage group I were usually resistant to penicillin and susceptible to ciprofloxacin, whereas the strains typeable with group V or group V with the 95 phage were susceptible to most antibiotics. Epidemic CA-MRSA strains (SCCmecIV) of phage type 80/81 carried Panton–Valentine leucocidin genes. Considering the high sensitivity of oral S. aureus to the analyzed phages and the promising results of phage therapies reported by other authors, phage cocktails or phage-antibiotic combinations may potentially find applications in both the prevention and eradication of staphylococcal infections.

LukS-PV Induces Apoptosis via the SET8-H4K20me1-PIK3CB Axis in Human Acute Myeloid Leukemia Cells.

Evidence suggests that histone modification disorders are involved in leukemia pathogenesis. We previously reported that LukS-PV, a component of Panton–Valentine leukocidin (PVL), has antileukemia activities that can induce differentiation, increase apoptosis, and inhibit proliferation of acute myeloid leukemia (AML) cells. Furthermore, LukS-PV inhibited hepatoma progression by regulating histone deacetylation, speculating that LukS-PV may exert antileukemia activity by targeting histone modification regulators. In this study, the results showed that LukS-PV induced apoptosis by downregulating the methyltransferase SET8 and its target histone H4 monomethylated at Lys 20 (H4K20me1). Furthermore, chromatin immunoprecipitation sequencing and polymerase chain reaction identified the kinase PIK3CB as a downstream target gene for apoptosis mediated by SET8/H4K20me1. Finally, our results indicated that LukS-PV induced apoptosis via the PIK3CB-AKT-FOXO1 signaling pathway by targeting SET8. This study indicates that SET8 downregulation is one of the mechanisms by which LukS-PV induces apoptosis in AML cells, suggesting that SET8 may be a potential therapeutic target for AML. Furthermore, LukS-PV may be a drug candidate for the treatment of AML that targets epigenetic modifications.

La pyomyosite, au-delà des tropiques

Pyomyositis, a bacterial infection of one or more skeletal muscles of the trunk, limbs, or pelvis, is most often caused by Staphylococcus aureus, apparently expressing the Panton and Valentine leukocidin toxin. Initially described as a tropical disease, it can occur in all climates, with a clear increase in its incidence, both in children and adults. It progresses in three anatomical stages leading to an abscessed collection. Risk factors exist but are inconsistent. It may be complicated by septic emboli depending on the delay in diagnosis and therefore management or the frailty of the patient. The presence of septic arthritis in the vicinity leads to discussion of the origin of the infection, primary versus secondary pyomyositis. Effective imaging includes ultrasound of the painful area, CT-scan and especially MRI. The microroganism is identified quite rarely on blood cultures, possibly on puncture under ultrasound or CT-scan of the infected muscle. Other bacteria than Staphylococcus aureus can be responsible. Sometimes pyomyositis is multi-bacterial. A PCR research by 16S ribosomal RNA in the muscle sampling material is proposed. Single muscle involvement with inflammatory syndrome also leads to discussion of focal myositis or muscle infarction. Pyomyositis implies systematic antibiotic therapy given for a period of three to four weeks, focused initially on Staphylococcus aureus, but sometimes also on a negative bacillus in the case of immunosuppression, and adapted subsequently according to bacteriological results/evolution. An abscessed fluid collection can be drained under ultrasound or CT-scan, and sometimes if necessary in the operating room.

Lateral Flow Immunoassay for the Detection of Panton-Valentine Leukocidin in Staphylococcus aureus From Skin and Soft Tissue Infections in the United Arab Emirates.

IntroductionPanton Valentine leukocidin (PVL) is a virulence factor which is associated with methicillin sensitive and resistant Staphylococcus aureus (MSSA/MRSA) causing skin and soft tissue infections (SSTI). This study aimed to evaluate a novel lateral flow immunoassay (LFI) for PVL detection in S. aureus cultures and to describe their genotypic characterization.MethodsThe study was carried out from January-August 2020 in Dubai, United Arab Emirates. S. aureus isolates associated with SSTI were tested for PVL detection using LFI. DNA microarray-based assays were used for molecular characterization including detection of pvl genes.ResultsOne-hundred thirty-five patients with a clinical diagnosis of SSTIs were recruited. Sixty-six patients received antibiotics, mostly beta lactams (n=36) and topical fusidic acid (n=15). One-hundred twenty-nine isolates (MRSA: n=43; MSSA: n=86) were tested by LFI and DNA microarrays. All 76 (58.9%) isolates which were unambiguously negative for the PVL in LFI were negative for pvl genes using the DNA microarray. All the LFI PVL positive isolates (n=53) had pvl genes detected. This translates into 100% each for sensitivity, specificity, positive and negative predictive values for the LFI. The LFI typically takes about 15 min inclusive of a 10 min incubation period. Predominant S. aureus clonal complexes (CC) were CC30 (n=18), CC22 (n=13), CC5 (n=12), CC1 (n=11), CC152 (n=8), CC15 (n=7); CC97 (n=7); CC8 and CC20 (n=6 each). Among MRSA, the proportion of pvl-positives (35/43; 81%) was higher than among MSSA (n/N=18/86; 21%). The fusidic acid resistance gene fusC was detected in 14 MRSA (33%) compared to 8 MSSA (9%). A co-carriage of fusC and pvl genes was present in 7 MRSA and in one MSSA.ConclusionLFI shows excellent diagnostic accuracy indices for rapid identification of PVL in MSSA/MRSA in a setting with high prevalence of pvl +ve strains. The high occurrence of pvl and fusC genes in MRSA strains causing SSTI is of concern and needs constant surveillance.

Methicillin-Resistant Staphylococcus aureus from Municipal Abattoirs in Nigeria: Showing Highly Similar Clones and Possible Transmission from Slaughter Animals to Humans.

In recent years, methicillin-resistant Staphylococcus aureus (MRSA) has gained interest in veterinary medicine due to its zoonotic potential. Currently, little information is available on the genotypic and virulence characteristics of MRSA isolates detected in Nigerian abattoirs. To better understand the epidemiology of MRSA associated with the abattoir food chain environment in Nigeria, a total of 18 isolates (humans: n = 5, slaughter animals: n = 5, and environment: n = 8), previously spa typed, were recovered and characterized by Staphylococcus cassette chromosome mec (SCCmec) typing, and phenotypic and genotypic antimicrobial susceptibility testing. In addition, 10 of the 18 MRSA strains with a new spa type (t16571) were subjected to multilocus sequence typing. The similarity of strains was analyzed based on the results of the DNA microarray analysis. The 18 MRSA strains harbored two distinct SCCmec types (IVa and V) and belonged to four clonal clusters (CC1, CC7, CC88, and CC152). All MRSA of the new spa type t16571 (n = 10) harbored the SCCmec type IVa. Seven of the MRSA t16571 strains belonged to ST88, while three other strains were assigned to ST3614. The 18 MRSA isolates were categorized into six virulence profiles, and the detection rate for the Panton-Valentine Leukocidin gene was high (33.3%). The antimicrobial susceptibility profiles of the 18 MRSA varied widely between strains, but phenotypic resistance corresponded to relevant resistance genes harbored. The detection of highly similar MRSA strains in slaughter animals, abattoir workers, and the environment underlines the need to use adequate measures at Nigerian abattoirs to prevent further spread and transmission of MRSA to humans or food.

Clonal Diversity and Molecular Characteristics of Methicillin-Susceptible and -Resistant Staphylococcus aureus from Pediatric Patients in Myanmar.

The spread of multidrug-resistant and virulent Staphylococcus aureus among children is a public health concern, but the actual conditions in Myanmar have not been characterized. In this study, a total of 244 clinical isolates of S. aureus collected from pediatric patients in Yangon Children's Hospital during a 1-year period were analyzed for their drug resistance and genetic features. Methicillin-resistant S. aureus (MRSA) accounted for 19.7% of isolates associated with staphylococcal cassette chromosome mec (SCCmec) type III, IV, or V. Panton-Valentine leukocidin (PVL) genes were detected in 61.5% of all isolates, with a significantly higher prevalence in methicillin-susceptible S. aureus (MSSA; 67.9%) than in MRSA (35.4%) isolates. Sequence type (ST) 239/SCCmec-III was the most common MRSA clone lacking PVL genes, while PVL-positive MRSA belonged to mostly ST361/SCCmec-V and ST772/SCCmec-V. Among MSSA isolates, ST121, ST2990, ST88, and ST1930 were dominant, harboring mostly PVL genes. ST239 MRSA isolates exhibited the highest resistance rates to antimicrobials, and quinolone resistance was found in the dominant MRSA clones (ST239, ST361, and ST772) and some MSSA lineages. The present study revealed the prevalence and clonal diversity of MRSA/MSSA in children in Myanmar in relation to drug resistance and virulence determinants.

Molecular Characterization of Staphylococcus aureus Isolated from Human and Food Samples in Northern Algeria.

Staphylococcus aureus is a commensal resident of the skin and nasal cavities of humans and can cause various infections. Some toxigenic strains can contaminate food matrices and cause foodborne intoxications. The present study aimed to provide relevant information (clonal complex lineages, agr types, virulence and antimicrobial resistance-associated genes) based on DNA microarray analyses as well as the origins and dissemination of several circulating clones of 60 Staphylococcus aureus isolated from food matrices (n = 24), clinical samples (n = 20), and nasal carriers (n = 16) in northern Algeria. Staphylococcus aureus were genotyped into 14 different clonal complexes. Out of 60 S. aureus, 13 and 10 isolates belonged to CC1-MSSA and CC97-MSSA, respectively. The CC 80-MRSA-IV was the predominant S. aureus strain in clinical isolates. The accessory gene regulator allele agr group III was mainly found among clinical isolates (70.4%). Panton–Valentine leukocidin genes lukF/lukS-PV were detected in 13.3% of isolates that all belonged to CC80-MRSA. The lukF/S-hlg, hlgA, and hla genes encoding for hemolysins and leucocidin components were detected in all Staphylococcus aureus isolates. Clinical and food isolates harbored more often the antibiotic resistance genes markers. Seventeen (28.3%) methicillin-resistant Staphylococcus aureus carrying the mecA gene localized on a SCCmec type IV element were identified. The penicillinase operon (blaZ/I/R) was found in 71.7% (43/60) of isolates. Food isolates belonging to CC97-MSSA carried several antibiotic resistance genes (blaZ, ermB, aphA3, sat, tetM, and tetK). The results of this study showed that all clones were found in their typical host, but interestingly, some nasal carriers had isolates assigned to CC705 thought to be absent in humans. The detection of MRSA strains among food isolates should be considered as a potential public health risk. Therefore, controlling the antibiotics prescription for a rational use in human and animal infections is mandatory.

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.

A CASE OF POST-OBSTRUCTIVE NECROTIZING PNEUMONIA IN THE SETTING OF METASTATIC NON-SMALL CELL LUNG CANCER

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Necrotizing pneumonia (NP) is a rare condition that is characterized by pulmonary liquefaction and necrosis. Associated symptoms are fever, chills, shortness of breath and cough. Advanced sequelae include pulmonary gangrene, empyema, abscess and hemoptysis. Prognosis is poor with an overall mortality rate of 56% [1]. Here, we present an unusual case of metastatic pulmonary adenocarcinoma complicated by NP leading to the patient's demise. CASE PRESENTATION: A 70 year old male smoker with no known PMH presented with productive cough, unintentional weight loss and hemoptysis. CT chest showed narrowing of the left main bronchus and left main pulmonary artery due to a possible hilar mass (Figure 1,2). There was also an extensive left-sided consolidation with pleural effusion. The patient's significant leukocytosis was poorly responsive to antibiotic therapy. No infectious etiology could be identified on extensive testing. The patient developed acute respiratory distress requiring mechanical ventilation. Bronchoscopy showed severe bleeding from an unidentifiable source in the left lung. BAL showed possible lung carcinoma with post-obstructive PNA. CT abdomen showed right adrenal metastasis. IR-guided bronchial artery embolism was attempted twice to control bleeding; however, no source of bleeding could be identified. The chest tube drained a considerable amount of serosanguinous fluid. The patient underwent segmentectomy after worsening bleeding through the ETT and was found to have extensive metastatic disease in the chest. Lobectomy could not be performed due to the inability to access hilum and was deemed unsafe. Biopsy showed poorly differentiated adenocarcinoma with venous invasion and thrombosis and NP with scattered bacterial colonies. The patient received compassionate care given a high likelihood of imminent death. DISCUSSION: The purpose of this case report was to describe a rare case of post-obstructive NP secondary to poorly differentiated metastatic lung adenocarcinoma. Current management of NP involves the surgical removal of the necrotic tissue along with a long course of broad-spectrum antibiotics to treat the underlying polymicrobial infection [2,3]. Our patient's prognosis was very poor because of the extent of his NP and malignancy. An early approach to endobronchial stenting would have stabilized the airway which was being severely compromised by the tumor, whereas a pneumonectomy would have made it easier to control the patient's fatal hemorrhage. This is why we believe that an early and aggressive intervention would have improved the patient's outcome. CONCLUSIONS: NP in the setting of advanced pulmonary adenocarcinoma is a rare phenomenon that is poorly described in current literature. If a patient with advanced lung cancer develops NP, an early surgical intervention with palliative stenting should be considered to minimize complications. REFERENCE #1: Gillet Y, Vanhems P, Lina G, Bes M, Vandenesch F, Floret D, Etienne J. Factors predicting mortality in necrotizing community-acquired pneumonia caused by Staphylococcus aureus containing Panton-Valentine leukocidin. Clin Infect Dis. 2007 Aug 1;45(3):315-21. doi: 10.1086/519263. Epub 2007 Jun 15. PMID: 17599308. REFERENCE #2: Cengiz AB, Kanra G, Caĝlar M, Kara A, Güçer S, Ince T. Fatal necrotizing pneumonia caused by group A streptococcus. J Paediatr Child Health. 2004 Jan-Feb;40(1-2):69-71. doi: 10.1111/j.1440-1754.2004.00296.x. PMID: 14718011. REFERENCE #3: Kohno S, Koga H, Oka M, et al: The pattern of respiratory infection in patients with lung cancer. Tohoku J Exp Med 173:405-411, 1994. DISCLOSURES: No relevant relationships by Frantzcess Compas, source=Web Response No relevant relationships by Zarwa Idrees, source=Web Response No relevant relationships by Vikram Sumbly, source=Web Response No relevant relationships by Theo Trandafirescu, source=Web Response

Genomic Investigation of Methicillin-Resistant Staphylococcus aureus ST113 Strains Isolated from Tertiary Care Hospitals in Pakistan.

Methicillin-resistant Staphylococcus aureus (MRSA) is a multi-drug resistant and opportunistic pathogen. The emergence of new clones of MRSA in both healthcare settings and the community warrants serious attention and epidemiological surveillance. However, epidemiological data of MRSA isolates from Pakistan are limited. We performed a whole-genome-based comparative analysis of two (P10 and R46) MRSA strains isolated from two provinces of Pakistan to understand the genetic diversity, sequence type (ST), and distribution of virulence and antibiotic-resistance genes. The strains belong to ST113 and harbor the SCCmec type IV encoding mecA gene. Both the strains contain two plasmids, and three and two complete prophage sequences are present in P10 and R46, respectively. The specific antibiotic resistance determinants in P10 include two aminoglycoside-resistance genes, aph(3’)-IIIa and aad(6), a streptothrin-resistance gene sat-4, a tetracycline-resistance gene tet(K), a mupirocin-resistance gene mupA, a point mutation in fusA conferring resistance to fusidic acid, and in strain R46 a specific plasmid associated gene ant(4’)-Ib. The strains harbor many virulence factors common to MRSA. However, no Panton-Valentine leucocidin (lukF-PV/lukS-PV) or toxic shock syndrome toxin (tsst) genes were detected in any of the genomes. The phylogenetic relationship of P10 and R46 with other prevailing MRSA strains suggests that ST113 strains are closely related to ST8 strains and ST113 strains are a single-locus variant of ST8. These findings provide important information concerning the emerging MRSA clone ST113 in Pakistan and the sequenced strains can be used as reference strains for the comparative genomic analysis of other MRSA strains in Pakistan and ST113 strains globally.

Molecular analysis of an increase in trimethoprim/sulfamethoxazole-resistant MRSA reveals multiple introductions into a tertiary care hospital, Germany 2012-19.

Increasing spread of resistance could jeopardize the use of antifolates against MRSA infections. We compared the prevalence of phenotypic trimethoprim/sulfamethoxazole resistance in 20 534 clinical Staphylococcus aureus isolates (19 096 MSSA and 1438 MRSA) of non-redundant patients at Heidelberg University Hospital over 8 years and performed WGS on trimethoprim/sulfamethoxazole-resistant MRSA. From 2012 to 2019, trimethoprim/sulfamethoxazole resistance in MSSA (674/19 096; 3.5%) ranged between 1.5% and 7.2% and in MRSA (135/1438; 9.4%) between 0.5% and 20.2%, reaching a peak in 2016 and 2018, respectively (Ptrend < 0.001). Trimethoprim/sulfamethoxazole resistance was more likely in outpatients than inpatients (P = 0.005), younger patients (P < 0.001), skin and soft tissue infections (SSTIs) (MRSA only, P = 0.05), submissions from pulmonology (MRSA only, P = 0.001), the upper respiratory tract (MSSA only, P < 0.001) and general surgery (MSSA only, P = 0.001). WGS of 76 trimethoprim/sulfamethoxazole-resistant MRSA revealed that 59% belonged to major pandemic CA-MRSA clones (ST22, ST8, ST398, ST772, ST30), 47% harboured Panton-Valentine leucocidin (PVL), 97% SCCmec IV/V, 71% dfrG and 28% dfrA. SNP-based phylogeny of trimethoprim/sulfamethoxazole-resistant MRSA core genomes favoured independent introduction over clonal expansion as the source, most prominently of dfrA+ trimethoprim/sulfamethoxazole-resistant ST22 MRSA from the Gaza Strip. The presented results support that trimethoprim/sulfamethoxazole-resistant S. aureus, formerly associated with SSTI from outpatients and S. aureus in the (sub)tropics, is on the rise in the temperate zone, potentially due to migration. Closer monitoring of trimethoprim/sulfamethoxazole resistance in S. aureus is recommended to safeguard the effectiveness of antifolate compounds.