Determination of antimicrobial susceptibility patterns of Nocardia spp. from clinical specimens by Etest

ABSTRACTSusceptibilities to 11 antimicrobial agents were determined by Etest for 93 Nocardia isolates from clinical specimens and 15 type strains belonging to different Nocardia spp. All isolates were susceptible to trimethoprim-sulphamethoxazole, amikacin and linezolid, but susceptibilities of the various Nocardia spp. to β-lactams, aminoglycosides, ciprofloxacin and clarithromycin varied markedly. Overall, there was a good correlation between the drug resistance patterns and the species identification established by conventional phenotypic tests and 16S rDNA sequencing. Among the different species encountered, Nocardia farcinica and Nocardia brasiliensis displayed the most multiresistant profiles, with resistance to imipenem occurring mainly among isolates of N. brasiliensis and Nocardia abscessus. The species variability in susceptibility profiles and the numerous recent taxonomic changes means that in-vitro susceptibility tests may be a complementary tool for the identification of Nocardia isolates from human clinical specimens. Further studies on a larger number of species from more diverse geographical sources, including species that are found less commonly among clinical isolates, are required to validate and extend the results

Optimization of the MALDIxin test for the rapid identification of colistin resistance in Klebsiella pneumoniae using MALDI-TOF-MS

Background. With the dissemination of carbapenemase producers, a revival of colistin was observed for the treatment of infections caused by multidrug-resistant Gram-negatives. Unfortunately, the increasing usage of colistin led to the emergence of resistance. In Klebsiella pneumoniae, colistin resistance arises through addition of L-arabinose-4N (L-Ara4N) or phosphoethanolamine (pEtN) on the native lipid A. The underlying mechanisms involve numerous chromosome-encoded genes or the plasmid-encoded phosphoethanolamine transferase MCR. Currently, detection of colistin resistance is time consuming since it still relies on MIC determination by broth microdilution. Recently, a rapid diagnostic test based on MALDI-TOF detection of modified lipid A was developed (the MALDIxin test) and tested on Escherichia coli and Acinetobacter baumannii. Objectives. Optimize the MALDIxin test for the rapid detection of colistin resistance in Klebsiella pneumoniae. Methods. This optimization consists on an additional mild-acid hydrolysis of 15 min in 1% acetic acid. The optimized method was tested on a collection of 81 clinical K. pneumoniae isolates including 49 colistin resistant strains among which 45 correspond to chromosome-encoded resistance, 3 MCR-related resistance and one isolate harbouring both mechanisms. Results. The optimized method allowed the rapid (< 30 min) identification of L-Ara4N and pEtN modified lipid A of K. pneumoniae which are known to be the real triggers of polymyxin resistance. In the same time, it discriminates between chromosome-encoded and MCR-related polymyxin resistance. Conclusions. The MALDIxin test has the potential to become an accurate tool for the rapid diagnostic of colistin resistance in clinically-relevant Gram negative bacteria

Helicobacter pylori and cancer among adults in Uganda

Data from Africa on infection with Helicobacter pylori (H. pylori) are sparse. Therefore, as part of an epidemiological study of cancer in Uganda, we investigated the prevalence and determinants of antibodies against H. pylori among 854 people with different cancer types and benign tumours. Patients were recruited from hospitals in Kampala, Uganda, interviewed about various demographic and lifestyle factors and tested for antibodies against H. pylori. In all patients combined, excluding those with stomach cancer (which has been associated with H. pylori infection), the prevalence of antibodies was 87% (723/833) overall, but declined with increasing age (p = 0.02) and was lower among people who were HIV seropositive compared to seronegative (p <0.001). Otherwise, there were few consistent epidemiological associations. Among those with stomach cancer, 18/21 (86%) had anti-H. pylori antibodies (odds ratio 0.8, 95% confidence intervals 0.2–2.9, p = 0.7; estimated using all other patients as controls, with adjustment for age, sex and HIV serostatus). No other cancer site or type was significantly associated with anti-H. pylori antibodies. The prevalence of H. pylori reported here is broadly in accord with results from other developing countries, although the determinants of infection and its' role in the aetiology of gastric cancer in Uganda remain unclear

Isocitrate Dehydrogenase of Helicobacter pylori Potentially Induces Humoral Immune Response in Subjects with Peptic Ulcer Disease and Gastritis

Background. H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori. Methodology/Principal Findings. Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD. Conclusions/Significance. ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent

Abscess of adrenal gland caused by disseminated subacute Nocardia farcinica pneumonia. A case report and mini-review of the literature

<p>Abstract</p> <p>Background</p> <p>Infections caused by <it>Nocardia farcinica </it>are uncommon and show a great variety of clinical manifestations in immunocompetent and immunocompromised patients. Because of its unspecific symptoms and tendency to disseminate it may mimic the clinical symptoms and radiologic findings of a tumour disease and the diagnosis of nocardiosis can easily be missed, because there are no characteristic symptoms.</p> <p>Case presentation</p> <p>We present a case of an adrenal gland abscess caused by subacute disseminated <it>N. farcinica </it>pneumonia.</p> <p>Conclusion</p> <p>An infection with <it>N. farcinica </it>is potentially lethal because of its tendency to disseminate -particularly in the brain- and its high resistance to antibiotics. Awareness of this differential diagnosis allows early and appropriate treatment to be administered.</p

The diagnostic value of endoscopy and Helicobacter pylori tests for peptic ulcer patients in late post-treatment setting

BACKGROUND: Guidelines for management of peptic ulcer patients after the treatment are largely directed to detection of H. pylori infection using only non-invasive tests. We compared the diagnostic value of non-invasive and endoscopy based H. pylori tests in a late post-treatment setting. METHODS: Altogether 34 patients with dyspeptic complaints were referred for gastroscopy 5 years after the treatment of peptic ulcer using a one-week triple therapy scheme. The endoscopic and histologic findings were evaluated according to the Sydney classification. Bacteriological, PCR and cytological investigations and (13)C-UBT tests were performed. RESULTS: Seventeen patients were defined H. pylori positive by (13)C-UBT test, PCR and histological examination. On endoscopy, peptic ulcer persisted in 4 H. pylori positive cases. Among the 6 cases with erosions of the gastric mucosa, only two patients were H. pylori positive. Mucosal atrophy and intestinal metaplasia were revealed both in the H. pylori positive and H. pylori negative cases. Bacteriological examination revealed three clarithromycin resistant H. pylori strains. Cytology failed to prove validity for diagnosing H. pylori in a post-treatment setting. CONCLUSIONS: In a late post-treatment setting, patients with dyspepsia should not be monitored only by non-invasive investigation methods; it is also justified to use the classical histological evaluation of H. pylori colonisation, PCR and bacteriology as they have shown good concordance with (13)C-UBT. Moreover, endoscopy and histological investigation of a gastric biopsy have proved to be the methods with an additional diagnostic value, providing the physician with information about inflammatory, atrophic and metaplastic lesions of the stomach in dyspeptic H. pylori positive and negative patients. Bacteriological methods are suggested for detecting the putative antimicrobial resistance of H. pylori, aimed at successful eradication of infection in persistent peptic ulcer cases

Efficacy of serology driven “test and treat strategy” for eradication of H. pylori in patients with rheumatic disease in the Netherlands

The treatment of choice of H. pylori infections is a 7-day triple-therapy with a proton pump inhibitor (PPI) plus amoxicillin and either clarithromycin or metronidazole, depending on local antibiotic resistance rates. The data on efficacy of eradication therapy in a group of rheumatology patients on long-term NSAID therapy are reported here. This study was part of a nationwide, multicenter RCT that took place in 2000–2002 in the Netherlands. Patients who tested positive for H. pylori IgG antibodies were included and randomly assigned to either eradication PPI-triple therapy or placebo. After completion, follow-up at 3 months was done by endoscopy and biopsies were sent for culture and histology. In the eradication group 13% (20/152, 95% CI 9–20%) and in the placebo group 79% (123/155, 95% CI 72–85%) of the patients were H. pylori positive by histology or culture. H. pylori was successfully eradicated in 91% of the patients who were fully compliant to therapy, compared to 50% of those who were not (difference of 41%; 95% CI 18–63%). Resistance percentages found in isolates of the placebo group were: 4% to clarithromycin, 19% to metronidazole, 1% to amoxicillin and 2% to tetracycline