Hepatitis B virus and hepatitis delta virus subtypes circulating in Algeria and seroprevalence of HDV infection.

BACKGROUND: Little is known about molecular characteristics of HBV strains circulating in Algeria and there are few data regarding HDV infection. OBJECTIVES: The aim of this study is to describe the genetic diversity of HBV and HDV strains existing in Algeria and to determine the seroprevalence of HDV infection. STUDY DESIGN: Plasma samples from 134 patients were analyzed by enzyme immunoassay method for HBV and HDV serological markers. Genotyping of HBV and HDV strains were performed using direct sequencing followed by phylogenetic analyses of the PreS1 and R0 region of the HBV and HDV genome respectively. RESULTS: The PreS1 gene was successfully amplified in 119 patients (82 males and 37 females). Phylogenetic analysis of HBV strains revealed the presence of genotypes D (86.5%) and A2 (11.76%). The subgenotypes D are distributed as follows: HBV/D7 (43.5%), HBV/D3 (24.75%), HBV/D1 (16.8%) and HBV/D2 (14.85%). A recombinant between genotypes A, E and D was found. The seroprevalence of HDV infection among HBV carriers was less than 5.35%. Only one isolate of HDV genotype 1 was identified. CONCLUSIONS: Our data indicate the predominance of HBV subgenotype D7 and a low prevalence of HDV infection.

Immunogenicity of toxins during Staphylococcus aureus infection.

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 polymerase chain reaction-defined presence of toxin genes in homologous S. aureus isolates. RESULTS: IgG levels directed to exfoliative toxin (ET) A, ETB, gamma hemolysin B (HlgB), leukocidin (Luk) D, LukE, LukS, staphylococcal enterotoxin (SE) A, SEE, SEH, SEI, and SElM were higher in S. aureus-infected patients than in control subjects (P < .05). Furthermore, in the S. aureus-infected patient group, IgG levels were higher if genes encoding ETA, ETB, SEA, SEC, SEH, SElQ, toxic shock syndrome toxin-1 (TSST-1), or Panton-Valentine leukocidin (PVL) were present in the infectious isolate (P< .05). Levels of anti-SEA IgG increased during infections with sea-positive (median fluorescence intensity from 11,555 to 12,388; P<.05) but not sea-negative strains. In addition, anti-LukS IgG levels increased during skin and soft-tissue infections with luk-PV-positive (median fluorescence intensity from 15,231 to 15,911; P<.05) but not luk-PV-negative strains. Bacteremia was associated with sea (odds ratio, 3.4; 95% confidence interval, 1.2-10.0) and tst (odds ratio, 5.7; 95% confidence interval, 1.6-20.8). Skin and soft-tissue infections and bone and joint infections were associated with luk-PV (odds ratio, 2.5; 95% confidence interval, 1.2-5.2). CONCLUSIONS: Many toxins are expressed in vivo and recognized by the immune system during staphylococcal infections, suggesting their involvement in S. aureus pathogenesis.

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

Staphylococcus aureus strains producing Panton-Valentine leukocidin (PVL) have been epidemiologically linked to specific human infections. To evaluate immunological tests that may be used to diagnose infections with PVL-producing strains, we prospectively collected pus, respiratory tract specimens, and joint fluid specimens from which S. aureus had been isolated in clinical laboratories in six countries. An enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic test (ICT) targeting LukS-PV were performed directly with clinical samples for the detection of PVL. The same tests were applied to S. aureus culture supernatants. The corresponding S. aureus isolates were characterized by PCR for the presence of the PVL locus (lukS-PV and lukF-PV) and the mecA gene. A total of 185 samples from 144 skin infections, 23 bone and joint infections, and 18 lower respiratory tract infections were analyzed. By PCR, 72/185 S. aureus isolates were PVL locus positive (PVL(+)); 28 of these were also mecA positive. PVL was detected in the supernatants of all PVL(+) strains by both ELISA and an ICT, while no signal was observed with PVL-negative strains. The PVL concentrations in human clinical samples that grew PVL(+) strains ranged from 0 to 399 microg/ml by ELISA. By the use of 0.015 microg/ml of PVL as a cutoff value, PVL was detected in 65/72 (90%) of the clinical samples by ELISA. The sensitivity and specificity of the ELISA test were 90% and 100%, respectively. By the ICT, PVL was detected in 57/72 (79%) of the samples, and the sensitivity and specificity of ICT were 79% and 100%, respectively. PVL is expressed by S. aureus during human infection, and a PVL-specific ELISA and ICT could be reliable tests for the diagnosis of infections caused by PVL-producing strains.

Serotypes and Antibiotic Susceptibility of Streptococcus pneumoniae Isolates from Invasive Pneumococcal Disease and Asymptomatic Carriage in a Pre-vaccination Period, in Algeria.

In Algeria, few data is available concerning the distribution of pneumococcal serotypes and respective antibiotic resistance for the current pre-vaccination period, which is a public health concern. We identified the most frequent Streptococcus pneumoniae serogroup/types implicated in invasive pneumococcal disease (IPD; n = 80) and carriage (n = 138) in Algerian children younger than 5 years old. Serogroup/types of 78 IPD isolates were identified by capsular typing using a sequential multiplex PCR. Overall, serotypes 14, 19F, 6B, 23F, 18C, 1, 5, 7F, 19A, and 3 (55% of PCV7 serotypes, 71.3% of PCV10, and 90% of PCV13) were identified. Additionally, 7.5% of the non-vaccine serotypes 6C, 9N/L, 20, 24F, 35B, and 35F, were observed. In the case of S. pneumoniae asymptomatic children carriers, the most common serogroup/types were 6B, 14, 19F, 23F, 4, 9V/A, 1, 19A, 6A, and 3 (42.7% of PCV7 serotypes, 44.2% of PCV10, and 58% of PCV13). For 6.1% of the cases co-colonization was detected. Serotypes 14, 1, 5, and 19A were more implicated in IPD (p < 0.01), whereas serotype 6A was exclusively isolated from carriers (p < 0.01). Deaths associated with IPD were related to serotypes 19A, 14, 18C, and one non-typeable isolate. Among IPD related to vaccine serotypes, the rates of penicillin non-susceptible isolates were higher in no meningitis cases (80%) than in meningitis (66.7%), with serotypes 14, 19A, 19F, and 23F presenting the highest MIC levels (>2µg/ml). Resistance to cefotaxime was higher in isolates from meningitis (40.5%); however, resistance to erythromycin and co-trimoxazole (>40%) was more pronounced in no-meningeal forms. Overall, our results showed that PCV13 conjugate vaccine would cover up to 90% of the circulating isolates associated with IPD in Algeria, highlighting the importance of monitoring the frequency of S. pneumoniae serogroups/types during pre- and post-vaccination periods.

High-Level Primary Clarithromycin Resistance of Helicobacter pylori in Algiers, Algeria: A Prospective Multicenter Molecular Study.

Knowledge of local antibiotic resistance is crucial to adaptation for the choice of the optimal first-line treatment for Helicobacter pylori infection. Clarithromycin is a key component of the standard triple therapy largely used worldwide and, more particularly, in Algeria. Clarithromycin resistance is the main risk factor for treatment failure. The aim of this study was to evaluate, for the first time in Algeria, the prevalence of the primary resistance of H. pylori to clarithromycin. We conducted a prospective study (2008-2014) that included 195 Algerian patients referred for gastroduodenal endoscopy to two University Hospitals, one General Hospital, and several private gastroenterologists in Algiers (Algeria). One gastric biopsy was collected for the molecular detection of H. pylori and the mutations in 23S rRNA genes that confer resistance to clarithromycin with a quadruplex real-time PCR using Scorpion primers. The Scorpion PCR detected H. pylori DNA in 91 biopsies (47%). A mutation conferring resistance to clarithromycin was detected in 32 of the 91 positive patients (35%) and in 29 of the 88 positive patients never previously treated for an H. pylori infection (33%). The prevalence of primary resistance of H. pylori to clarithromycin was 33% in the Algerian population being studied. The high level of primary clarithromycin resistance in the H. pylori strains infecting the Algerian population that we report leads us to recommend the abandonment of the standard clarithromycin-based triple therapy as a first-line treatment in Algeria.

Capsular typing of Streptococcus pneumoniae isolated in an Algerian hospital using a new multiplex PCR-based scheme.

We developed a new sequential multiplex-PCR-based typing scheme (MPBTS) for pneumococcal capsular classification. The serogroup/type of 37 control isolates obtained by the Quellung reaction, MPBTS, and nucleotide sequencing, were fully concordant. The serogroups/types of 75 invasive isolates determined by MPBTS, presented 100% specificity and 96% sensitivity, when compared with the Quellung reaction.

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

Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hospital in Algeria, carried the novel ß-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 ß-lactamases, i.e. EcDH5α-SHV-98, EcDH5α-SHV-99 and EcDH5α-SHV-100, respectively, carried unique sequence features of bla(SHV) gene variants, enabling oxyimino-cephalosporin susceptibility and confirming that none of the transformants exhibited extended-spectrum ß-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 ß-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 (K(m) of 196 µM), catalytic activity (k(cat) of 0.5 s⁻¹) and catalytic efficiency (k(cat)/K(m) of 0.003 µM⁻¹ s⁻¹) than SHV-1 ß-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.

CTX-M-3 and CTX-M-15 extended-spectrum beta-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) beta-lactamases. Fourteen of the isolates are multidrug resistant. Five isolates from the neonatal ward were indistinguishable by pulsed-field gel electrophoresis.

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.