Main Bacterial Pathogens Research Articles

Temporal changes in the genotypes of methicillin-resistant Staphylococcus aureus strains isolated from a tertiary Malaysian hospital based on MLST, spa, and mec-associated dru typing

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main bacterial pathogens responsible for nosocomial infections leading to pneumonia, bloodstream, skin, and soft tissue infections. The objective of this study was to investigate the genomic changes of MRSA in a tertiary hospital between the years 2003, 2004, 2007, and 2008. One hundred fifty-four MRSA strains were characterized by multilocus sequence typing (MLST), spa, and mec-associated dru typing. Among the 154 strains, 29 different dru, 15 spa, and 8 MLST types were identified. Seven sequence types (STs) (ST239, ST22, ST5, ST6, ST80, ST573, and ST241) were identified among 2007–08 strains, although only 2 STs (ST239 and ST20) were observed among 2003 strains. Clones ST239-t037-dt13g, ST22-t032-(dt10a and dt10aw), and 28 other MRSA clones being introduced in 2007–2008 have replaced the ST239-t037 (dt13d, 14h, 13i, 13l, 13m, 15m, 15l, and 11al) clones present in 2003. The predominant MLST clone, ST239 (90.3%), was further distinguished into 7 different spa types and 26 different dru types, including 17 novel dru types. Maximum parsimony tree based on dru repeats revealed that 10 dru types (dt11am, dt13j, dt15n, dt13q, dt13n, dt13p, dt13f, dt13ao, dt12j, dt7v) shared the same MLST–spa types with dt13d, suggesting that these MRSA clones might have evolved from ST239-t037-dt13d. In conclusion, our data showed that the ST239-t037-dt13d clone and other MRSA clones in 2003 were replaced by ST239-t037-dt13g and other new emerging spa and dru types.

Scientific Opinion on Public health risks represented by certain composite products containing food of animal origin

This Opinion reviews the factors that affect microbial survival and growth in composite products, and in foods in general. It concludes that the main factors to be considered are: water activity, pH, temperature and duration of storage, processing, and intensity and duration of other non-thermal physical processes applied. Prevalence and concentration of the pathogens in food are important to determine the risk for consumers. The opinion presents a review of the quantitative microbiology models and databases that can be used to provide quantitative estimations of the impact of the above factors on the survival and growth of the main bacterial pathogens. In composite products, migration and diffusion of moisture and substances among the ingredients may change their physico-chemical parameters, particularly at the interfaces. Therefore, the assessment of the risk posed by composite products needs to consider the combinations of parameters most permissive to survival and growth of pathogens. Two complementary approaches are proposed for the identification and profiling of microbiological hazards in different specific composite products. The first one is based on past outbreaks and prevalence of hazards in the products and leads to the conclusion that the most frequent hazard-composite product combinations are Salmonella in cakes and bakery products. The second one consists in decision tools based on the impact on the pathogens of food composition and food processing. Categorisation of the risk for composite products requires information on their composition, processing and further handling, which can largely differ for foods belonging to the same category. Further conditions may influence the risk and should be verified, i.e. hygienic conditions during preparation of the composite products and their ingredients, shelf-life conditions, and reliability of cooking by consumers to inactivate pathogens. The decision tools developed apply to all composite products considered by the mandate, as well as to all other foods. © European Food Safety Authority, 2012

Acylhomoserine Lactone Production by Bacteria Associated with Cultivated Mushrooms

The main bacterial pathogens of cultivated mushroom as well as mushroom-associated bacteria, which were isolated from Agaricus bisporus, Pleurotus ostreatus and Pleurotus eryngii mushroom niches, were evaluated for the production of N-acyl-L-homoserine lactones (AHLs) by using four bioreporters. Furthermore, identification of AHLs by LC-ESI-FTICR MS was performed on culture filtrates of selected pathogens and mushroom-associated bacteria strains, which resulted in inducing at least one of the four bioreporters. Strains of Burkolderia gladioli pv. agariciola, Pseudomonas agarici and Pseudomonas gingeri, but not those of Pseudomonas tolaasii and Pseudomonas reactans, produced an array of AHLs depending on the strain. This is the first report of AHL production by mushroom bacterial pathogens. Forty-four of 236 bacterial isolates obtained from different niches of cultivated mushrooms, in part identified by the Biolog identification system, were demonstrated to produce AHLs. Among them, seven mushroom-associated bacterial species were for the first time demonstrated to produce the above signal molecules. In the culture filtrates of a certain number of isolates/strains the AHL-hydrolyzed forms were also present. The minimal signal inducing concentration (MSIC) of selected pure AHLs was also determined for the four bioreporters used in this study.

Epidemiology of nosocomial bacteria resistant to antimicrobials

Nosocomial infections are a major challenge for public health because of the high rates of morbidity and mortality generated. It was considered that the excessive or inappropriate use of antibiotics triggers the emergence of resistant strains. Among the clinically important bacteria that most commonly cause nososcomial infections, Gram positive multiresistant pathogens stand out such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp (VRE), and the Gram negative strains of Klebsiella pneumoniae, Escherichia coli, Pseudomonas spp. and Acinetobacter baumannii producing expanded spectrum b-lactamases (ESbL). This review describes the behavior of the main bacterial pathogens resistant to antibiotics that cause infections in Europe, United States, and Latin America, emphasizing studies of molecular epidemiology on a global scale, including the major epidemiological studies in Colombia. The genetic structure of S. aureus and Enterococcus spp strains shows a clonal characteristic favored by the predominance of a small number of clones with the capacity to spread globally, due probably to cross-infection. However, the introduction of MRSA strains from the community encourages genetic diversity, tending to establish a genetic polyclonal endemic structure in places like the United States. In Gram negative bacteria, the high genetic diversity among isolates, mainly in Latin American countries, indicates that the polyclonal spread is influenced by horizontal transfer of plasmids, by excessive exposure to antibiotics, and prolonged hospital stays. In Colombia, there is information on nosocomial resistant pathogens, but molecular epidemiological information is still scarce.

Etiología de metritis bovina en rebaños lecheros de las Regiones V y Metropolitana (Chile) y resistencia bacteriana frente a diferentes antimicrobianos

Peri or postpartum reproduction disorders are predisposing factors for the development of uterine infections that produce important economic. The metritis is multifactorial, being bacterial the determinant cause of the disease. In spite of antimicrobial therapy which is one of the most important therapeutic tools against this pathology, the developmentof multiple resistance in animals pathogens has been reported. Inappropriate treatment produce economic losses and increase of the bacterial resistance to antimicrobial. The aim of this study was to determinate the main bacterial pathogens isolated from bovine metritis and their antimicrobial susceptibility. A total of 265 strains were isolated from uterine samples from dairy herd in the yh and Metropolitan Regions (Chile), being the principal pathogens isolated E. coli (19.2%) and A. pyogenes (18.1%). The susceptibility test show a higher resistance to betalactamic antimicrobial. Streptococcus spp and CNS were highly resistant (>70%) to lincomicin; in A. pyogenes we observed a resistance > to28% to enrofloxacin and cefquinome. A higher susceptibility was observed in A.pyogenes, CNS and Streptococcus spp to cefapirine and gentamicine. The major resistance to oxitetracicline (38.5%) was observed in Streptococcus spp strains. The E. coli strains were most resistant to cefquinome and oxitetracicline. The analysis of resistant profiles demonstrated that Streptococcus spp and CNS strains were multiresistant. According to these results it is possible to conclude that the bovine pathogens metritiswere resistant to more than one antimicrobial drug and, therefore, usageof these drugs it should be undermedical prescription. Finally, these results stressed the necessity to promote a permanent monitoring programof bacterial resistance in veterinary medicine in our country.

A kinetic study of the cytokine/chemokines levels and disruption of blood-brain barrier in infant rats after pneumococcal meningitis

Bacterial meningitis is an inflammation of the meninges and subarachnoid space that occurs in response of bacteria. Young children are particularly vulnerable to bacterial meningitis, two thirds of meningitis deaths in low-income countries occur among children under the age of fifteen. The main bacterial pathogens causing meningitis beyond the neonatal period are Streptococcus pneumoniae, Haemophilus influenza type b and Neisseria meningitidis. Therefore, the aim of this study is to evaluate the kinetic and the levels of TNF-α, IL-1β, IL-6, IL-10 and CINC-1 in different brain regions as well as the blood-brain barrier permeability after meningitis induced by S. pneumoniae in infant Wistar rats. The animals underwent a magna cistern tap receiving either 10μL sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration 1×106CFU/mL. The animals were killed at different times after induction. The brain was removed and the hippocampus and the cortex were isolated and used for the determination of cytokine/chemokine levels and blood-brain barrier permeability. The cerebrospinal fluid was obtained by puncture of the cisterna magna to TNF-α and IL-1β analysis. In the hippocampus, the CINC-1 and IL-1β levels were found increased at 6h, 12h and 24h after pneumococcal meningitis induction. In the cortex the levels of the CINC-1 were increased at 6h, 12h and 24h. The IL-1β and TNF-α were increased at 12h and 24h. The level of IL-6 was increased only after 24h after pneumococcal meningitis induction. In cerebrospinal fluid, the TNF-α was increased at 12h, 24h and IL-1 was increased at 24h after S. pneumoniae induction. The blood-brain barrier breakdown in hippocampus and cortex were observed at 12h until 24h during meningitis. In conclusion, a peak of pro-inflammatory cytokine/chemokine is associated with disruption of the blood-brain barrier in infants with pneumococcal meningitis.

Diagnosis and detection of the main bacterial pathogens of stone fruit and almond

SUMMARY Diagnosis and detection are key aspects related to plant health status. A critical review of the available diagnostic methods utilised for Agrobacterium rhizogenes and A. tumefaciens, Pseudomonas amygdali, P. syringae pv. mors-prunorum, P. syringae pv. persicae, P. syringae pv. syringae and Xanthomonas arboricola pv. pruni, the main pathogens of the stone fruit trees, is presented. As there is a general lack of updated standardized protocols for the detection of most of these bacteria, the most appropriate media for their isolation are reported along with serological reagents, PCR and real-time PCR protocols with comments on their accuracy for the analysis of these pathogens in plant samples. There are many selective media for isolation, especially for Agrobacterium spp., but fewer for Pseudomonas spp. and X. arboricola pv. pruni. Serological techniques are not very useful for these pathogens due to the current lack of specific antibodies commercially available. As to molecular methods, it is surprising to find so many PCR protocols for Agrobacterium species, very few and unspecific for the Pseudomonas species pathogenic to stone fruit trees, and several recent PCR protocols for X. arboricola pv. pruni. The new advances in genomics and proteomics will provide information for selecting new targets to develop specific and sensitive techniques for the diagnosis and detection of these bacterial pathogens in plant material.

Bacterial pathogens in wild birds: a review of the frequency and effects of infection

The importance of wild birds as potential vectors of disease has received recent renewed empirical interest, especially regarding human health. Understanding the spread of bacterial pathogens in wild birds may serve as a useful model for examining the spread of other disease organisms, both amongst birds, and from birds to other taxa. Information regarding the normal gastrointestinal bacterial flora is limited for the majority of wild bird species, with the few well-studied examples concentrating on bacteria that are zoonotic and/or relate to avian species of commercial interest. However, most studies are limited by small sample sizes, the frequent absence of longitudinal data, and the constraints of using selective techniques to isolate specific pathogens. The pathogenic genera found in the gut are often those suspected to exist in the birds' habitat, and although correlations are made between bacterial pathogens in the avian gut and those found in their foraging grounds, little is known about the effect of the pathogen on the host, unless the causative organism is lethal. In this review, we provide an overview of the main bacterial pathogens isolated from birds (with particular emphasis on enteropathogenic bacteria) which have the potential to cause disease in both birds and humans, whilst drawing attention to the limitations of traditional detection methods and possible study biases. We consider factors likely to affect the susceptibility of birds to bacterial pathogens, including environmental exposure and heterogeneities within the host population, and present probable avenues of disease transmission amongst birds and from birds to other animal taxa. Our primary aim is to identify gaps in current knowledge and to propose areas for future study.

Risk factors for sternal wound infection in children undergoing cardiac surgery: a case–control study

Complex and prolonged cardiovascular operations are increasingly performed on young infants and children. The aims of this study were to define the incidence, causative bacterial pathogens and risk factors for sternal wound infections (SWIs) in infants and children undergoing cardiac surgery. The study group included all children who underwent cardiac surgery by median sternotomy at a tertiary paediatric centre from 1999 to 2003 and who were diagnosed with a postoperative SWI. Charts were reviewed for pre-, intra- and postoperative variables. The findings were compared with control patients operated on immediately before and after the cases and analysed by a stepwise logistic regression model. Of the 1821 children who underwent cardiac surgery, 49 (2.69%) had SWI; full data were available for 47. Twenty-nine (61.7%) had superficial wound infection and 18 (38.3%) deep wound infection. The main bacterial pathogens were Staphylococcus aureus in 14 patients (39%) and Pseudomonas aeruginosa in 12 (33%). Three variables emerged as significant independent risk factors for SWI: young age (odds ratio: 0.63; 95% confidence interval: 0.47-0.85; P<0.001 for each additional year), cyanotic heart disease (4.93; 1.98-12.3; P<0.001), and central venous catheter (CVC) dwell time (1.15; 1.06-1.24; P<0.001 for each additional day). Gram-negative infections were significantly associated with preoperative oxygen treatment (P=0.007) and prolonged urinary catheter dwell time (P=0.004). This study confirms younger age as risk factor for SWI and adds cyanotic heart disease and duration of CVC as new independent risk factors. Specific risks for Gram-negative infections are identified and should help to introduce new preventive strategies to decrease the incidence and severity of SWI.

Population Structure of the Fish-Pathogenic Bacterium Flavobacterium psychrophilum

Flavobacterium psychrophilum is currently one of the main bacterial pathogens hampering the productivity of salmonid farming worldwide, and its control mainly relies on antibiotic treatments. To better understand the population structure of this bacterium and its mode of evolution, we have examined the nucleotide polymorphisms at 11 protein-coding loci of the core genome in a set of 50 isolates. These isolates were selected to represent the broadest possible diversity, originating from 10 different host fish species and four continents. The nucleotide diversity between pairs of sequences amounted to fewer than four differences per kilobase on average, corresponding to a particularly low level of diversity, possibly indicative of a small effective-population size. The recombination rate, however, seemed remarkably high, and as a consequence, most of the isolates harbored unique combinations of alleles (33 distinct sequence types were resolved). The analysis also showed the existence of several clonal complexes with worldwide geographic distribution but marked association with particular fish species. Such an association could reflect preferential routes of transmission and/or adaptive niche specialization. The analysis provided no clues that the initial range of the bacterium was originally limited to North America. Instead, the historical record of the expansion of the pathogen may reflect the spread of a few clonal complexes. As a resource for future epidemiological surveys, a multilocus sequence typing website based on seven highly informative loci is available.

Pathogen Proteins Eliciting Antibodies Do Not Share Epitopes with Host Proteins: A Bioinformatics Approach

The best way to prevent diseases caused by pathogens is by the use of vaccines. The advent of genomics enables genome-wide searches of new vaccine candidates, called reverse vaccinology. The most common strategy to apply reverse vaccinology is by designing subunit recombinant vaccines, which usually generate an humoral immune response due to B-cell epitopes in proteins. A major problem for this strategy is the identification of protective immunogenic proteins from the surfome of the pathogen. Epitope mimicry may lead to auto-immune phenomena related to several human diseases. A sequence-based computational analysis has been carried out applying the BLASTP algorithm. Therefore, two huge databases have been created, one with the most complete and current linear B-cell epitopes, and the other one with the surface-protein sequences of the main human respiratory bacterial pathogens. We found that none of the 7353 linear B-cell epitopes analysed shares any sequence identity region with human proteins capable of generating antibodies, and that only 1% of the 2175 exposed proteins analysed contain a stretch of shared sequence with the human proteome. These findings suggest the existence of a mechanism to avoid autoimmunity. We also propose a strategy for corroborating or warning about the viability of a protein linear B-cell epitope as a putative vaccine candidate in a reverse vaccinology study; so, epitopes without any sequence identity with human proteins should be very good vaccine candidates, and the other way around.

Antibacterial activity of carbapenems against clinically isolated respiratory bacterial pathogens in Japan between 2005 and 2006

The current status of the susceptibility of the main respiratory bacterial pathogens was evaluated by analysing the antibacterial activity of 21 drugs, including four carbapenems, against five species of the pathogens isolated between January 2005 and January 2006. A total of 157 strains were studied. Carbapenems inhibited the growth of all of the tested strains of Moraxella catarrhalis, Streptococcus pneumoniae and methicillin-susceptible Staphylococcus aureus strains at concentrations that were below the breakpoints set by the Japanese Society of Chemotherapy (2 and 1 μg/mL for pneumonia and chronic respiratory tract infection, respectively). However, the majority of methicillin-resistant Staphylococcus aureus strains were resistant to carbapenems. Meropenem, but not the other carbapenems, inhibited the growth of all of the tested strains of Haemophilus influenzae isolates, including β-lactamase-non-producing ampicillin-resistant strains, at concentrations of ≤1 μg/mL. The MIC 50 and MIC 90 of meropenem , 0.25 and 4 μg/mL, against Pseudomonas aeruginosa were the lowest of the carbapenems. By comparing these results with our previous data, it was found that there was no increase in resistance to carbapenems in any of the species tested. Thus, it can be stated that carbapenems have retained their position as key drugs for severe respiratory tract infections.

Near Infrared Spectra of Cows' Milk for Milk Quality Evaluation: Disease Diagnosis and Pathogen Identification

Food quality and safety, as well as bacteria identification, have become very important issues. Establishing fast and non-destructive methods for control is of a great importance. The performance and safety of processed milk and milk products are influenced by the quality of the raw milk used and animal health. Cell count in udder quarter milk has been established as the main criteria by which milk abnormality is evaluated and, in addition to electrical conductivity and pathogen identification, it is also a principle means for the diagnosis of the inflammatory udder disease known as mastitis. Near infrared (NIR) spectroscopy has proved to be a fast non-destructive method for the analysis of food and agricultural products, including non-homogenised milk. In this study, we have analysed NIR spectra of udder quarter milk samples collected continuously from individual cows, at various farms, at different times of the year. We report that NIR spectra of cows' udder quarter milk, when subjected to multivariate data analysis, provides information about milk abnormality and health disorders in cows. We have developed spectroscopic models for the simultaneous measurement of somatic cell count and electrical conductivity, as well as for identification of the main mastitis-causing bacterial pathogens in cow's udder quarter milk. These findings present NIR spectroscopy as a powerful technology for in vivo health monitoring, disease diagnosis at molecular level and bacteria identification.

A member of the cathelicidin family of antimicrobial peptides is produced in the upper airway of the chinchilla and its mRNA expression is altered by common viral and bacterial co-pathogens of otitis media

Cationic antimicrobial peptides (AMPs), a component of the innate immune system, play a major role in defense of mucosal surfaces against a wide spectrum of microorganisms such as viral and bacterial co-pathogens of the polymicrobial disease otitis media (OM). To further understand the role of AMPs in OM, we cloned a cDNA encoding a cathelicidin homolog (cCRAMP) from upper respiratory tract (URT) mucosae of the chinchilla, the predominant host used to model experimental OM. Recombinant cCRAMP exhibited alpha-helical secondary structure and killed the three main bacterial pathogens of OM. In situ hybridization showed cCRAMP mRNA production in epithelium of the chinchilla Eustachian tube and RT-PCR was used to amplify cCRAMP mRNA from several other tissues of the chinchilla URT. Quantitative RT-PCR analysis of chinchilla middle ear epithelial cells (CMEEs) incubated with either viral (influenza A virus, adenovirus, or RSV) or bacterial (nontypeable H. influenzae, M. catarrhalis, or S. pneumoniae) pathogens associated with OM demonstrated distinct microbe-specific patterns of altered expression. Collectively, these data showed that viruses and bacteria modulate AMP messages in the URT, which likely contributes to the disease course of OM.

PK and PK/PD of doxycycline in drinking water after therapeutic use in pigs

A commercial doxycycline formulation was administered in drinking water to 12 pigs at the recommended dose of 10 mg/kg daily for 5 days. The mean plasma concentration at steady-state was 1.37 +/- 1.21 microg/mL, which was reached at 68 +/- 27.2 h postadministration. Absorption and elimination half-life values were 7.20 +/- 2.42 and 7.01 +/- 2.10 h, respectively. Most plasma concentrations during dosing were higher than the minimum inhibitory concentrations (MICs) described for the main porcine bacterial pathogens of the respiratory tract (Pasteurella multocida, Actinobacillus pleuropneumoniae, Bordetella bronchiseptica and Mycoplasma hyopneumoniae). It is concluded that when pigs were treated with doxycycline in drinking water at the recommended rate, therapeutically effective concentrations were achieved throughout the treatment period, supporting the clinical use of this tetracycline in the control of respiratory infections. However, inter-animal differences were marked.

Is there any specific association between respiratory viruses and bacteria in acute otitis media of young children?

SummaryBackgroundRespiratory viral infections are usually preceding or coinciding with acute otitis media (AOM) in children. It is not known if a given viral infection would facilitate invasion of bacterial pathogens into the middle ear in a species-specific way. We reanalysed the microbiological results of the two prospective Finnish Otitis Media (FinOM) studies for this purpose.MethodsThe children had been followed from 2 months to 2 years of age in specific study clinics and all referred AOM events were analysed. Combined results of virus detection tests from middle ear fluid and nasopharyngeal aspirate and those of bacterial culture from middle ear fluid were cross-tabulated for 529 AOM events in the FinOM Cohort Study and for 364 events in the FinOM Vaccine Trial.ResultsIn both studies the main bacterial pathogens were Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis while the main viruses detected were rhinoviruses and respiratory syncytial virus (plus enteroviruses in the Vaccine Trial). No distinct species-specific associations were observed between the viral and bacterial findings.ConclusionWe did not find support to the theory that respiratory infection caused by a given viral species would favour growth of a certain bacterial pathogen in the MEF more than another.

Mycobacterium tuberculosis - the 10 years of epidemiological and diagnostics studies

Tuberculosis (ТВ) is the main bacterial pathogen that causes more deaths than AIDS, malaria and all infectious diseases. The unusual long doubling time (about 24h), highly hydrophobic cell envelope resistant to chemical lysis was the reason to delay the molecular study of this bacteria. Fifteen years ago, we did not have any molecular tools and methods for genetic manipulation or isolation and analysis of intracellular protein and nucleic acids. Today we have many useful shuttle or integration vectors for basic study of mycobacteria. The full sequence of M. tuberculosis genome is already known. At the present time the diagnosis of tuberculosis is supported with fast-culture system BACTEC and molecular techniques based on PCR and DNA hybridization. The mechanisms of resistance to antituberculosis drugs were described, and first identification of resistance profile is available by using PCR and sequencing or real time PCR methods. In our group in the Center for Microbiology and Virology Polish Academy of Sciences and in the Dept, of Genetics of Microorganisms, University Łódź we have characterized new insertion sequences from M. tuberculosis complex- 18990 and IS1607. In diagnostic studies we have proposed the DIG-PCR ELISA assay as a reliable, specific and sensitive test to identify M. tuberculosis directly in clinical samples. We have performed wide epidemiological studies of M. tuberculosis strains isolated from Polish ТВ patients including drug - and multidrug - resistant strains. Finally we identified the most frequently present mutations responsible for drug resistance of polish clinical isolates of M. tuberculosis.

Clinical efficacy of cefpodoxime in respiratory tract infection.

Acute otitis media (AOM), sinusitis and tonsillopharyngitis are respiratory tract infections frequently encountered by primary-care physicians. Increasing bacterial resistance, particularly in Streptococcus pneumoniae, which is one of the most important respiratory tract bacteria implicated in community-acquired respiratory tract infections, has led to concern about the current options for empirical antibiotic treatment and has prompted a search for effective alternative treatments. Data from in vitro studies show that cefpodoxime has good activity against the main respiratory tract pathogens, S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. Clinical studies confirm the efficacy of cefpodoxime in AOM, sinusitis and tonsillopharyngitis. As with all broad-spectrum antibiotics, there is the risk of promotion of bacterial resistance associated with overuse. However, if used with care, cefpodoxime can be considered as an alternative for empirical treatment of bacterial respiratory tract infections encountered in general practice, particularly where penicillins and macrolides have reduced efficacy against the main bacterial pathogens.

Risk and Case Fatality Rate of Meningitis in Patients with Liver Cirrhosis

Bacterial infections are major causes of morbidity and death in patients with liver cirrhosis. The risk of bacterial meningitis in these patients is unknown, however. In this study on a nation-wide cohort of 22,743 patients with liver cirrhosis in Denmark an incidence rate of bacterial meningitis of 54.4 per 100,000 was found [95% confidence interval (CI) 40.3-71.9]. The highest incidence rate was found in patients with alcoholic cirrhosis, 65.3 per 100,000 person-years (95% CI 46.2-89.6), compared with 34.6 per 100,000 person-years (95% CI 17.3-61.9) in patients with non-alcoholic cirrhosis. The 30-d case fatality rate was 53.1% (95% CI 38.3-67.5), and high age and alcoholic cirrhosis were associated with the highest case fatality rates. The main bacterial pathogens were pneumococci and unspecified bacteria. These findings suggest that patients with liver cirrhosis are at increased risk of bacterial meningitis with a poor prognosis.

Atypical respiratory pathogens.

The main atypical pathogens in respiratory tract infections are classified on the basis of their ability to cause atypical pneumonia. This is not a well‐defined clinical entity, and it is evident that atypical pathogens can sometimes cause ‘typical’ pneumonias and vice versa. This emphasizes the need for microbiological diagnosis, since it affects the selection of proper treatment, in which β‐lactam antibiotics and aminoglycosides are not effective. Moreover, mixed infections caused by atypical and typical pathogens together are common. At this moment rapid and sensitive diagnostic methods are lacking. Besides numerous viruses, the main bacterial pathogens causing atypical pneumonias are Mycoplasma pneumoniae, two chlamydia species. Chlamydia pneumoniae and C. psittaci, one rickettsia, Coxiella burnetti, and several Legionella species. The majority of these pathogens cause upper respiratory tract infections more often than overt pneumonias. An atypical agent, Chlamydia pneumoniae, has also been associated with chronic inflammatory conditions in the cardiovascular system. The most recently discovered pathogen in atypical pneumonias is a hantavirus causing hantavirus pulmonary syndrome.