Rapid detection of Staphylococcus aureus Panton-Valentine leukocidin in clinical specimens by enzyme-linked immunosorbent assay and immunochromatographic tests

10.1128/JCM.02274-09Journal of Clinical Microbiology4841384-139

Immunogenicity of toxins during Staphylococcus aureus infection

AB - BACKGROUND: Toxins are important Staphylococcus aureus virulence factors, but little is known about their immunogenicity during infection. Here, additional insight is generated. METHODS: Serum samples from 206 S. aureus-infected patients and 201 hospital-admitted control subjects were analyzed for immunoglobulin (Ig) G binding to 20 toxins, using flow-cytometry based technology. Antibody levels were associated with p

IgG4 subclass-specific responses to Staphylococcus aureus antigens shed new light on host-pathogen interaction

textabstractIgG4 responses are considered indicative for long-term or repeated exposure to particular antigens. Therefore, studying IgG4-specific antibody responses against Staphylococcus aureus might generate new insights into the respective host-pathogen interactions and the microbial virulence factors involved. Using a bead-based flow cytometry assay, we determined total IgG (IgGt), IgG1, and IgG4 antibody responses to 40 different S. aureus virulence factors in sera from healthy persistent nasal carriers, healthy persistent noncarriers, and patients with various staphylococcal infections from three distinct countries. IgGt responses were detected against all tested antigens. These were mostly IgG1 responses. In contrast, IgG4 antibodies were detected to alphatoxin, chemotaxis inhibitory protein of S. aureus (CHIPS), exfoliative toxins A and B (ETA and-B), HlgB, IsdA, LukD,-E,-F, and-S, staphylococcal complement inhibitor (SCIN), staphylococcal enterotoxin C (SEC), staphylococcal superantigen-like proteins 1, 3, 5, and 9 (SSL1,-3,-5, and-9), and toxic shock syndrome toxin 1 (TSST-1) only. Large interpatient variability was observed, and the type of infection or geographical location did not reveal conserved patterns of response. As persistent S. aureus carriers trended toward IgG4 responses to a larger number of antigens than persistent noncarriers, we also investigated sera from patients with epidermolysis bullosa (EB), a genetic blistering disease associated with high S. aureus carriage rates. EB patients responded immunologically to significantly more antigens than noncarriers and trended toward even more responses than carriers. Altogether, we conclude that the IgG4 responses against a restricted panel of staphylococcal antigens consisting primarily of immune modulators and particular toxins indicate important roles for these virulence factors in staphylococcal pathogen-host interactions, such as chronicity of colonization and/or (subclinical) infections

CTX-M-3 and CTX-M-15 Extended-Spectrum β-Lactamases in Isolates of Escherichia coli from a Hospital in Algiers, Algeria

Sixteen strains of Escherichia coli isolated between January and June 2005 in a hospital in Algiers carry the ISEcp1 element and the TEM and either CTX-M-3 (n = 3) or CTX-M-15 (n = 13) β-lactamases. Fourteen of the isolates are multidrug resistant. Five isolates from the neonatal ward were indistinguishable by pulsed-field gel electrophoresis

Staphylococcus aureus isolated from selected dairies of Algeria: Prevalence and susceptibility to antibiotics

Aim: The objectives of this study were to assess the prevalence of Staphylococcus aureus in raw milk in Algerian dairies, to study the effect of seasons on the contamination of milk and the susceptibility of isolated strains to antibiotics, and to estimate the risk on the health consumer. Materials and Methods: The ISO method 6888-1 (1) was used for Staphylococcus screening. Antimicrobial susceptibility to the 11most used antibiotics in veterinary medicine was assessed using the disk diffusion assay. Results: The overall prevalence was 31.56% (95/301); 34.84% (85/244) from raw milk collectors cisterns (MCC), 22.73% (5/22) from mixing tank milk before pasteurization, and 14.29% (5/35) from pasteurized tank milk (p<0.05). A significant difference (p<0.001) of contamination on MCC was observed between dairies without season influence (p≥0.05). It was observed that 49.47% of S. aureus isolates were resistant to penicillin, 5.26% to tetracycline, 4.21% to erythromycin, 3.15% to neomycin, 2.10% to cefoxitin, 2.10% to clindamycin, and 1.05% to ofloxacin. No resistance was observed for vancomycin, gentamicin, chloramphenicol, and trimethoprim-sulfamethoxazole. Conclusion: A high prevalence of S. aureus from MCC was observed without significant effect of season. The pasteurization does not ensure the elimination of bacteria in all samples. Half of the isolates were resistant to penicillin. These findings emphasize the importance of S. aureus control in Algerian milk industry at different levels to improve public health

Role of SHV β-lactamase variants in resistance of clinical Klebsiella pneumoniae strains to β-lactams in an Algerian hospital

Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hospital in Algeria, carried the novel β-lactamases SHV-98, SHV-99 and SHV-100, respectively, and co-expressed TEM-1 and either CTX-M-3 or CTX-M-15. In contrast, transformed cells possessing the genes for these novel β-lactamases, i.e. EcDH5α-SHV-98, EcDH5α-SHV-99 and EcDH5α-SHV-100, respectively, carried unique sequence features of blaSHV gene variants, enabling oxyimino-cephalosporin susceptibility and confirming that none of the transformants exhibited extended-spectrum β-lactamase (ESBL) properties. SHV-100 is apparently functional, despite differing from the SHV-1 sequence by duplication of 13 amino acids. The SHV-99 enzyme differed from the parental SHV-1 by the amino acid substitution Asp104→Gly, which is an important position in the development of the ESBL phenotype in TEM β-lactamases. This is the first time, to our knowledge, that this mutation has been reported in clinically occurring isolates. Thus, kinetic characterization of the SHV-99 enzyme was performed. The SHV-99 enzyme showed higher affinity (Km of 196 µM), catalytic activity (kcat of 0.5 s−1) and catalytic efficiency (kcat/Km of 0.003 µM−1 s−1) than SHV-1 β-lactamase against aztreonam. These results showed that the neutral glycine at residue 104 increased the affinity of the enzyme to aztreonam, but was unable to develop the ESBL phenotype in SHV enzymes. As the emergence of new threatening combinations of resistance determinants among nosocomial pathogens is further possible, this study has highlighted the need to reverse the spread of initial mutations

Detection of Methicillin-Resistant Staphylococcus aureus Strains Resistant to Multiple Antibiotics and Carrying the Panton-Valentine Leukocidin Genes in an Algiers Hospital

Forty-five Panton-Valentine leukocidin (PVL)-positive, methicillin-resistant Staphylococcus aureus strains were isolated in Algeria between 2003 and 2004; 18 isolates were isolated in the community and 27 in a hospital. Five PVL-positive hospital isolates were resistant to multiple antibiotics, including ofloxacin and gentamicin for three isolates

High levels of Staphylococcus aureus and MRSA carriage in healthy population of Algiers revealed by additional enrichment and multisite screening

International audienceThe purpose of the research is to characterize Staphylococcus aureus colonization in healthy population of Algiers, to assess the impact on diagnostic performance of systematic additional broth enrichment, and to ascertain the additional benefits of multiple site screening. In order to more accurately determine the prevalence of S. aureus colonization, the swab specimens from multiple screening sites were incubated in brain-heart broth before agar plating. From 2009 to 2011, 1176 samples were collected from 459 participants (201 adults and 258 children). The additional enrichment detection step significantly increased S. aureus detection rates (p \textless 0.0001). S. aureus nasal detection was positive in 37.8% of adults, and the addition of throat samplings significantly increased the S. aureus detection rate up to 54.7% (p \textless 0.001). S. aureus nasal detection was positive in 37.6% of children. The addition of throat samplings in children significantly increased the S. aureus detection rate up to 53.1% (p \textless 0.001) and that of anal samplings up to 59.7%. The overall prevalence of methicillin-resistant S. aureus was 5.2% (3% of adults and 7% of children). spa typing of all isolates revealed a diverse but strongly clonal S. aureus population structure. This approach involving multiple anatomical sampling sites and an additional enrichment of the swabs before conventional culture significantly increases the detection rate of S. aureus carriers and may prove valuable to improve global S. aureus infection prevention

IgG4 subclass-specific responses to Staphylococcus aureus antigens shed new light on host-pathogen interaction

IgG4 responses are considered indicative for long-term or repeated exposure to particular antigens. Therefore, studying IgG4-specific antibody responses against Staphylococcus aureus might generate new insights into the respective host-pathogen interactions and the microbial virulence factors involved. Using a bead-based flow cytometry assay, we determined total IgG (IgGt), IgG1, and IgG4 antibody responses to 40 different S. aureus virulence factors in sera from healthy persistent nasal carriers, healthy persistent noncarriers, and patients with various staphylococcal infections from three distinct countries. IgGt responses were detected against all tested antigens. These were mostly IgG1 responses. In contrast, IgG4 antibodies were detected to alphatoxin, chemotaxis inhibitory protein of S. aureus (CHIPS), exfoliative toxins A and B (ETA and-B), HlgB, IsdA, LukD,-E,-F, and-S, staphylococcal complement inhibitor (SCIN), staphylococcal enterotoxin C (SEC), staphylococcal superantigen-like proteins 1, 3, 5, and 9 (SSL1,-3,-5, and-9), and toxic shock syndrome toxin 1 (TSST-1) only. Large interpatient variability was observed, and the type of infection or geographical location did not reveal conserved patterns of response. As persistent S. aureus carriers trended toward IgG4 responses to a larger number of antigens than persistent noncarriers, we also investigated sera from patients with epidermolysis bullosa (EB), a genetic blistering disease associated with high S. aureus carriage rates. EB patients responded immunologically to significantly more antigens than noncarriers and trended toward even more responses than carriers. Altogether, we conclude that the IgG4 responses against a restricted panel of staphylococcal antigens consisting primarily of immune modulators and particular toxins indicate important roles for these virulence factor