Use of an experimental model to evaluate infection resistance of meshes in abdominal wall surgery.

BACKGROUND: Staphylococcal species are the most common organisms causing prosthetic mesh infections, however, infections due to rapidly growing mycobacteria are increasing. This study evaluates the resistance of biomaterial for abdominal wall prostheses against the development of postoperative infection in a rat model. MATERIAL AND METHODS: In 75 rats, we intramuscularly implanted three different types of prostheses: (1) low-density polypropylene monofilament mesh (PMM), (2) high-density PMM, and (3) a composite prosthesis composed of low-density PMM and a nonporous hydrophilic film. Meshes were inoculated with a suspension containing 108 colony-forming units of Staphylococcus aureus, Staphylococcus epidermidis, Mycobacterium fortuitum, or Mycobacterium abscessus before wound closure. Animals were sacrificed on the eighth day postoperatively for clinical evaluation, and the implants were removed for bacteriologic analyses. RESULTS: Prostheses infected with S aureus showed a higher bacterial viability, worse integration, and clinical outcome compared with infection by other bacteria. Composite prostheses showed a higher number of viable colonies of both M fortuitum and Staphylococcus spp., with poorer integration in host tissue. However, when the composite prosthesis was infected with M abscessus, a lower number of viable bacteria were isolated and a better integration was observed compared with infection by other bacteria. CONCLUSIONS: Considering M abscessus, a smaller collagen-free contact surface shows better resistance to infection, however, depending on the type of bacteria, prostheses with a large surface, and covered with collagen shows reduced resistance to infection, worse integration, and worse clinical outcome.

Risk factors and clinical significance of invasive infections caused by levofloxacin-resistant Streptococcus pneumoniae.

PURPOSE: Fluoroquinolones are recommended for the treatment of pneumonia. The recognition of risk factors for invasive levofloxacin-resistant Streptococcus pneumoniae is important for the design of treatment. METHODS: A retrospective review of cases of invasive pneumococcal infections in adults was undertaken. Epidemiologic data, predisposing factors, clinical variables, and outcome were recorded from previously established protocols. Antimicrobial susceptibility was determined by disk diffusion and the Etest method. Serotyping was performed by latex agglutination and Quellung reaction. RESULTS: Twenty patients with infection caused by levofloxacin-resistant pneumococci [minimum inhibitory concentration (MIC) ≥2 µg/ml] were compared with 102 patients harboring levofloxacin-susceptible strains; 80% of levofloxacin-resistant pneumococci were resistant to ≥3 antibiotics but susceptible to penicillin. Most levofloxacin-resistant strains (80%) belonged to serotype 8. In comparison, only 8% of levofloxacin-susceptible pneumococci belonged to serotype 8. In the multivariate analysis, residence in public shelters [odds ratio (OR) 26.13; p 0.002], previous hospitalization (OR 61.77; p < 0.001), human immunodeficiency virus (HIV) infection (OR 28.14; p = 0.009), and heavy smoking (OR 14.41; p = 0.016) were associated with an increased risk of infection by levofloxacin-resistant pneumococci. Mortality caused by levofloxacin-resistant and levofloxacin-susceptible pneumococci was 35 and 14%, respectively. Among HIV-positive individuals infected with levofloxacin-resistant pneumococci 44% died, but only 12.5% of HIV-positive patients with levofloxacin-susceptible strains died. CONCLUSIONS: We observed the emergence of serotype 8 as the main cause of invasive disease caused by levofloxacin-resistant S. pneumoniae. HIV-positive patients seem to be prone to infection caused by multidrug-resistant serotype 8 and have a high mortality rate.

Mycobacterium africanum, an emerging disease in high-income countries?

BACKGROUND: Mycobacterium africanum is a cause of tuberculosis (TB) that has mainly been described in Africa, but immigration and travel patterns have contributed to the spread of the disease to other countries. METHODS: We retrospectively reviewed TB cases due to M. africanum during 2000-2010 in seven Spanish hospitals. Selected clinical charts were reviewed using a predefined protocol that included demographical, clinical and microbiological data and outcome. RESULTS: Although 57 cases were diagnosed, only 36 clinical charts were available for review: 82.8% were men and the mean age was 31.6 years (range 12-81). Forty-four cases were from Africa, 1 from the Philippines, 1 from India, and 4 from Spain, while the country of origin was unknown in 7 cases. The most frequent site of infection was the lung (58.3%). Four cases (6.9%) were resistant to at least one first-line anti-tuberculosis drug. CONCLUSIONS: Disease due to M. africanum in industrialised countries is mainly associated with immigration from endemic areas, although some cases also occur among native-born populations.