Extended role for insertion sequence elements in the antibiotic resistance of Bacteroides

The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.

Small intestinal bacterial overgrowth syndrome

Human intestinal microbiota create a complex polymi-crobial ecology. This is characterised by its high population density, wide diversity and complexity of interaction. Any dysbalance of this complex intestinal microbiome, both qualitative and quantitative, might have serious health consequence for a macro-organism, including small intestinal bacterial overgrowth syndrome (SIBO).SIBO is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastro-intestinal tract. There are several endogenous defence mechanisms for preventing bacterial overgrowth: gastric acid secretion, intestinal motility, intact ileo-caecal valve, immunoglobulins within intestinal secretion and bacte-riostatic properties of pancreatic and biliary secretion. Aetiology of SIBO is usually complex, associated with disorders of protective antibacterial mechanisms (e.g. achlorhydria, pancreatic exocrine insuff iciency, immuno-deficiency syndromes), anatomical abnormalities (e.g. small intestinal obstruction, diverticula, f istulae, surgical blind loop, previous ileo-caecal resections) and/or motility disorders (e.g. scleroderma, autonomic neuropathy in diabetes mellitus, post-radiation enteropathy, small intestinal pseudo-obstruction). In some patients more than one factor may be involved. Symptoms related to SIBO are bloating, diarrhoea, malabsorption, weight loss and malnutrition. The gold standard for diagnosing SIBO is still microbial investigation of jejunal aspirates. Noninvasive hydrogen and methane breath tests are most commonly used for the diagnosis of SIBO using glucose or lactulose. Therapy for SIBO must be com-plex, addressing all causes, symptoms and complica-tions, and fully individualised. It should include treatment of the underlying disease, nutritional support and cyclical gastro-intestinal selective antibiotics. Prognosis is usually serious, determined mostly by the underlying disease that led to SIBO.

Bacteriocinogeny in experimental pigs treated with indomethacin and Escherichia coli Nissle

AIM： To evaluate bacteriocinogeny in short-term highdose indomethacin administration with or without probiotic Escherichia coli Nissle 1917 （EcN） in experimental pigs.METHODS： Twenty-four pigs entered the study： Group A （controls）, Group B （probiotics alone）, Group C （indomethacin alone） and Group D （probiotics and indomethacin）. EcN （3.5 × 10^10 bacteria/d for 14 d） and/or indomethacin （15 mg/kg per day for 10 d） were administrated orally. Anal smears before and smears from the small and large intestine were taken from all animals. Bacteriocin production was determined with 6 different indicator strains; all strains were polymerase chain reaction tested for the presence of 29 individual bacteriocinencoding determinants. RESULTS： The general microbiota profile was rather uniform in all animals but there was a broad diversity in coliform bacteria （parallel genotypes A, B1, B2 and D found）. In total, 637 bacterial strains were tested, mostly Escherichia coli （E. coli. There was a higher incidence of non-E：, coli strains among samples taken from the jejunum and ileum compared to that of the colon and rectum indicating predominance of E. coil strains in the large intestine. Bacteriocinogeny was found in 24/77 （31%） before and in 155/560 （28%） isolated bacteria at the end of the study. Altogether, 13 individual bacteriocin types （out of 29 tested） were identified among investigated strains. Incidence of four E. coli genotypes was equally distributed in all groups of E. coil strains, with majority of genotype A （ranging from 81% to 88%）. The following types of bacteriocins were most commonly revealed： colicins Ia/Ib （44%）, microcin V （18%）, colicin E1 （16%） and microcin H47 （6%）. There was a difference in bacteriocinogeny between control group A （52/149, 35%） and groups with treatment at the end of the study： B： 31/122 （25%, P = 0.120）; C： 43/155 （28%, P = 0.222）; D： 29/134 （22%, P = 0.020）. There was a significantly lower prevalence of colicin Ib, microcins H47 and V （probiotics group, P 〈 0.001）, colicin E1 and microcin H47 （indomethacin group, P 〈 0.001） and microcins H47 and V （probiotics and indomethacin group, P = 0.025） compared to controis. Escherichia fergusonil （E. fergusoniO was identi-fled in 6 animals （6/11 isolates from the rectum）. One strain was non-colicinogenic, while all other strains of E. fergusonii solely produced colicin El. All animals started and remained methanogenic despite the fact that EcN is a substantial hydrogen producer. There was an increase in breath methane （after the treatment） in 5/6 pigs from the indomethacin group （C）. CONCLUSION： EcN did not exert long-term liveabilib/ in the porcine intestine, All experimental pigs remained methanogenic, Indomethacin and EcN administered together might produce the worst impact on bacteriocinogeny.

Antimicrobial susceptibility of Enterobacteriaceae causing urinary tract infections： a central military hospital study

Urinary tract infection （UTI） remains one of the most common bacterial infections seen in hospitalized patients of all ages. Prevalence of UTIs increases with age and is often accompanied by higher resistance rates. The aim of this study was to determine the degree of resistance of most common enterobacterial uropathogens isolated from patients at Central Military Hospital and compare this resistance with the results found by the North America and Europe Study for Monitoring Antimicrobial Resistance Trends （SMART） study during 2009-2010.

Successful elimination of extended-spectrum beta-lactamase (ESBL)-producing nosocomial bacteria at a neonatal intensive care unit

Background:Extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria are highly dangerous to neonates.At our Neonatal Intensive Care Unit (NICU),the presence of these bacteria became so threatening in 2011 that immediate intervention was required.Methods:This study was conducted during a nearly two-year period consisting of three phases:retrospective (9 months),educational (3 months) and prospective (9 months).Based on retrospective data analysis,a complex management plan was devised involving the introduction of the INSURE protocol,changes to the antibiotic regimen,microbiological screening at short intervals,progressive feeding,a safer bathing protocol,staff hand hygiene training and continuous monitoring of the number of newly infected and newly colonized patients.During these intervals,a total of 355 patients were monitored.Results:Both ESBL-producing Enterobacter cloaceae and Klebsiella pneumoniae were found (in both patients and environmental samples).In the prospective period a significant reduction could be seen in the average number of both colonized (26/167 patients;P=0.029) and infected (3/167 patients;P=0.033) patients compared to data from the retrospective period regarding colonized (72/188 patients) and infected (9/188 patients) patients.There was a decrease in the average number of patientdays (from 343.72 to 292.44 days per months),though this difference is not significant (P=0.058).During the prospective period,indirect hand hygiene compliance showed a significant increase (from the previous 26.02 to 33.6 hand hygiene procedures per patient per hospital day,P<0.001).Conclusion:Colonizations and infections were rolled back successfully in a multi-step effort that required an interdisciplinary approach.