SUMMARY: Haemophilus influenzaeis a major community-acquired pathogen causing significant morbidity and mortality worldwide. Meningitis and bacteremia due to type b strains occur in areas where the protein-conjugated type b vaccine is not in use, whereas nontypeable strains are major causes of otitis media, sinusitis, acute exacerbations of chronic bronchitis, and pneumonia. Antibiotic resistance in this organism is more diverse and widespread than is commonly appreciated. Intrinsic efflux resistance mechanisms limit the activity of the macrolides, azalides, and ketolides. β-Lactamase production is highly prevalent worldwide and is associated with resistance to ampicillin and amoxicillin. Strains with alterations in penicillin binding proteins, particularly PBP3 (β-lactamase negative ampicillin resistant and β-lactamase positive amoxicillin-clavulanate resistant), are increasing in prevalence, particularly in Japan, with increasing resistance to ampicillin, amoxicillin, amoxicillin-clavulanate, and many cephalosporins, limiting the efficacy of expanded-spectrum cephalosporins against meningitis and of many oral cephalosporins against other diseases. Most strains remain susceptible to the carbapenems, which are not affected by penicillin binding protein changes, and the quinolones. The activity of many oral agents is limited by pharmacokinetics achieved with administration by this route, and the susceptibility of isolates based on pharmacokinetic and pharmacodynamic parameters is reviewed.

Gut microbiota is established during birth and evolves with age, mostly maintaining the commensal relationship with the host. A growing body of clinical evidence suggests an intricate relationship between the gut microbiota and the immune system. With ageing, the gut microbiota develops significant imbalances in the major phyla such as the anaerobic Firmicutes and Bacteroidetes as well as a diverse range of facultative organisms, resulting in impaired immune responses. Antimicrobial therapy is commonly used for the treatment of infections; however, this may also result in the loss of normal gut flora. Advanced age, antibiotic use, underlying diseases, infections, hormonal differences, circadian rhythm, and malnutrition, either alone or in combination, contribute to the problem. This nonbeneficial gastrointestinal modulation may be reversed by judicious and controlled use of antibiotics and the appropriate use of prebiotics and probiotics. In certain persistent, recurrent settings, the option of faecal microbiota transplantation can be explored. The aim of the current review is to focus on the establishment and alteration of gut microbiota, with ageing. The review also discusses the potential role of gut microbiota in regulating the immune system, together with its function in healthy and diseased state.

Distribution of the microbiota varies according to the location in the gastrointestinal (GI) tract. Thus, dysbiosis during aging may not be limited to faecal microbiota and extend to the other parts of the GI tract, especially the cecum and colon. Lactobacillus acidophilus DDS-1, a probiotic strain, has been shown to modulate faecal microbiota and its associated metabolic phenotype in aging mice. In the present study, we investigated the effect of L. acidophilus DDS-1 supplementation on caecal- and mucosal-associated microbiota, short-chain fatty acids (SCFAs) and immunological profiles in young and aging C57BL/6J mice. Besides differences in the young and aging control groups, we observed microbial shifts in caecal and mucosal samples, leading to an alteration in SCFA levels and immune response. DDS-1 treatment increased the abundances of beneficial bacteria such as Akkermansia spp. and Lactobacillus spp. more effectively in caecal samples than in mucosal samples. DDS-1 also enhanced the levels of butyrate, while downregulating the production of inflammatory cytokines (IL-6, IL-1β, IL-1α, MCP-1, MIP-1α, MIP-1β, IL-12 and IFN-γ) in serum and colonic explants. Our findings suggest distinct patterns of intestinal microbiota, improvements in SCFA and immunological profiles with DDS-1 supplementation in aging mice.

To characterize the β-lactam resistance mechanisms of two clinical isolates of cefotaxime-resistant Haemophilus parainfluenzae recovered from patients in South Africa. The relatedness of isolates and plasmids was assessed using PFGE and restriction enzyme analysis, respectively. Plasmid-mediated and chromosomally integrated bla_TEM genes and ftsI genes were sequenced, and the plasmid-mediated bla_TEM-15 was used to transform a range of control organisms. The two isolates were found to be unique according to PFGE, but had an identical 3.7 kb plasmid encoding a TEM-15 β-lactamase. Both isolates also had substitutions in penicillin binding protein 3 (PBP3) consistent with substitutions known to exist in β-lactamase-negative ampicillin-resistant (BLNAR) strains of Haemophilusinfluenzae. The cefotaxime MICs for control strains of H. influenzae, H. parainfluenzae and BLNAR H. influenzae transformed with the plasmid-mediated bla_TEM-15 were 1.0, 1.0 and 4.0 mg/L, respectively, compared with 16.0 and 8.0 mg/L, respectively, for the two parent H. parainfluenzae. The high-level cefotaxime resistance in the H. parainfluenzae isolates was due to a combination of a plasmid-mediated TEM-15 extended-spectrum β-lactamase with altered PBP3 probably contributing. Other contributing resistance mechanisms could not be excluded.

Objectives: To establish a multiplex PCR to detect and differentiate the β-lactamase genes of Haemophilus influenzae. Methods: A collection of H. influenzae isolates with a range of different β-lactamase genes were tested in parallel with individual PCRs and the multiplex assay developed in this study. Results: The multiplex method was found to be superior to previous methods and was able to correctly detect and differentiate bla_ROB-1 and the variants of bla_TEM present in the strains tested, including a previously unrecognized variant associated with a 54 bp insertion in the promoter region. Conclusions: The multiplex PCR will be a useful tool for the surveillance of β-lactamase genes in H. influenzae.