Latitude of the study place and age of the patient are associated with incidence of mediastinitis and microbiology in open-heart surgery: a systematic review and meta-analysis.

OBJECTIVE: We aimed to summarize the pooled frequency of mediastinitis following open-heart surgery caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and Gram-negative bacteria. DESIGN: This study was a systematic review and a meta-analysis of prospective and retrospective cohort studies. MATERIALS AND METHODS: We searched the literature, and a total of 97 cohort studies were identified. Random-effect model was used to synthesize the results. Heterogeneity between studies was examined by subgroup and meta-regression analyses, considering study and patient-level variables. Small-study effect was evaluated. RESULTS: Substantial heterogeneity was present. The estimated incidence of mediastinitis evaluated from 97 studies was 1.58% (95% confidence intervals [CI] 1.42, 1.75) and that of Gram-positive bacteria, Gram-negative bacteria, and MRSA bacteria evaluated from 63 studies was 0.90% (95% CI 0.81, 1.21), 0.24% (95% CI 0.18, 0.32), and 0.08% (95% CI 0.05, 0.12), respectively. A meta-regression pinpointed negative association between the frequency of mediastinitis and latitude of study place and positive association between the frequency of mediastinitis and the age of the patient at operation. Multivariate meta-regression showed that prospective cohort design and age of the patients and latitude of study place together or in combination accounted for 17% of heterogeneity for end point frequency of mediastinitis, 16.3% for Gram-positive bacteria, 14.7% for Gram-negative bacteria, and 23.3% for MRSA bacteria. CONCLUSION: Evidence from this study suggests the importance of latitude of study place and advanced age as risk factors of mediastinitis. Latitude is a marker of thermally regulated bacterial virulence and other local surgical practice. There is concern of increasing risk of mediastinitis and of MRSA in elderly patients undergoing sternotomy.

Endotoxin-induced local inflammation and hyperalgesia in rats and mice: a new model for inflammatory pain.

Lipopolysaccharide, also known as endotoxin (ET), is a major constituent of the outer membrane of the cell wall of most gram negative bacteria. ET is known to cause a number of pathophysiological changes associated with illness including inflammatory pain. The aim of this study is to characterize the peripheral hyperalgesia induced by ET in rats and mice. Different groups of rats and mice received different doses of ET ranging from 0.6 microgram to 40 micrograms dissolved in 50 microliters saline and injected in the plantar area of the left hind legs. All animals were subjected to tail immersion (TF), hot plate (HP) and paw pressure (PP) tests, 2-3 days prior to ET injection and during the following 1-2 days. ET injections produced a dose-dependent decrease in the latencies of the HP and PP tests of the injected leg reaching a maximum decrease of 50-60% of the control with 20-40 micrograms ET at 9 h (rats) and 24 h (mice) after the injection. Almost complete recovery was observed after 24 h in rats and 48 h in mice. TF latencies showed a less but a significant decrease while PP of the opposite leg and all tests in saline-injected animals did not elicit significant variations and served as additional controls. Our results indicate that the use of ET-produced hyperalgesia is a valid model for local and reversible inflammatory pain, with minimal distress to the animal. This model can also be used to study the efficacy of various anti-inflammatory and analgesic drugs and the molecular mechanisms of inflammation induced by bacterial invasion.

Different virus antibodies in serum and cerebrospinal fluid of patients suffering from subacute sclerosing panencephalitis.

Complement fixing (CF) antibody titers to measles, parainfluenza (PI) types 1 and 3, mumps, herpes type 1, and cytomegalovirus (CMV) in serum and cerebrospinal fluid (CSF) of 33 patients with subacute sclerosing panencephalitis (SSPE) were evaluated. Results were analyzed in comparison to 11 patients with neurological diseases other than SSPE and 7 normal subjects. All SSPE patients had elevated serum and CSF measles antibody titers. The number of SSPE patients manifesting elevated titers other than measles did not reach statistical significance when compared to controls, except for PI type 1. This suggests a possible dual infection with measles and PI in SSPE. The anticomplementary effect detected in the serum and CSF of some patients indirectly suggests the presence of immune complexes.

Effect of gram-negative bacterial lipopolysaccharide-derived polysaccharides, glycolipids, and lipopolysaccharides on rabbit and human platelets in vitro.

The in vitro effect of gram-negative bacterial LPS-derived polysaccharide (PS), glycolipid (GL), and lipopolysaccharide (LPS) was investigated both on rabbit and human platelets. Rabbit platelets aggregated when they were treated with either GL or LPS, but no aggregation occurred when PS was used. No aggregation occurred when human platelets were treated with LPS, PS, or GL. However, when either human or rabbit platelets were treated with LPS-antibody complexes (LPS-ab), aggregation took place. Guinea-pig serum inhibited the aggregation caused by LPS-ab, but had no effect on rabbit platelet aggregation caused by LPS or GL alone. The factor(s) in guinea-pig serum that inhibited aggregation was heat-stable. These results suggest that there may be two different mechanisms involved in rabbit platelet aggregation by endotoxin in vitro. Using human platelets, only one mechanism was observed.

Plasmid DNA vaccines.

Genes that code for the production of protein antigens have been cloned and recombined with plasmids. Gene-plasmid constructs have been amplified in a bacterial host, purified and administered to a mammalian host. The gene is expressed in the host and the antigen that is produced induces an immune response. These so-called DNA vaccines have been prepared for a number of infectious agents, some tumors and some allergens, and were shown to be efficacious in animal studies. Clinical trials for some of these vaccines are underway. Advantages of using a DNA vaccine include the abilities to favor a T helper-1 or a T helper-2 lymphocyte response and to induce a cytotoxic T-lymphocyte response. Moreover, some reports have indicated that they produce long-lasting immunity. DNA vaccines might be used in situations where no effective vaccine is available for a disease. However, their use might not be risk-free. Further research in this field is needed to determine their efficacy and to identify the risks involved in using them.

Human leukocyte antigen frequencies in a selected group of Lebanese Greek Orthodox.

HLA classes I and II profiles were determined among 45 unrelated Lebanese Greek Orthodox by the complement dependent lymphomicrocytotoxicity assay. HLA epitope frequencies and alleles in linkage disequilibrium were determined; the obtained results were then compared to those reported for other groups. Moreover, possible HLA-disease associations were examined; medical history in relation to diabetes, rheumatoid arthritis, and ankylosing spondilitis was taken for each of the 45 individuals. The results indicated that: 1) There were similarities and differences in HLA frequencies and alleles in linkage disequilibrium in Greek Orthodox as compared to those in other groups. It is worth mentioning the higher frequencies of B35, DR11, and DQ3 and the existence of linkage disequilibrium between DR11 and DR52 and DR4 and DR53 in Greek Orthodox. 2) Preliminary results indicate that there were no significant HLA-disease associations between each of DR4 and rheumatoid arthritis, DR4 and insulin dependent diabetes mellitus (IDDM), and B27 and ankylosing spondilitis in the group studied. Such associations have been reported in North American Caucasians.

Antigen processing/presenting and oncogenesis.

It has been established in recent years that a number of tumor cell types express tumor antigens, yet the host's immune system fails to recognize them. The antigen processing/presenting machinery, which plays a crucial role in generating an immune response, and possible causes for its inability of processing/presenting tumor antigens are reviewed. These causes are related to the expression of major histocompatibility complex molecules, costimulatory molecules, and tumor antigens by tumor cells, and the types of cytokines produced. Therapeutic measures include transfecting tumor cells with genes that encode major histocompatibility complex and costimulatory molecules, cytokines, and tumor antigens. In addition, tumor peptide vaccines are evaluated. However, developing an immune response to tumor antigens carries with it the risk of autoimmune disease.

Characterization of some vibrio parahaemolyticus strains isolated from seafoods in Lebanon.

One hundred and seventy seafood specimens were investigated for the presence of Vibrio parahaemolyticus. V. parahaemolyticus was isolated from two fish and one crab specimens, and V. alginolyticus was isolated from seven fish, three shrimp, two sea-urchin and one crab specimens. The V. parhaemolyticus isolates had biochemical characteristics that were similar to two standard strains. Like the standard strains, two of the V. parahaemolyticus isolates were Kangawa phenomenon positive and were serologically similar to one of the standard strains. One isolate exhibited slight cross reactivity with V. alginolyticus but no cross reactivity with E. coli. One of the V. alginolyticus isolates was Kanagawa-phenomenon positive.

Identification of allergens in a selected group of asthmatics in Lebanon.

Anti-allergen antibodies were searched for by an Enzyme Immunoassay in the sera obtained from 60 patients with a clinical diagnosis of asthma. Allergic rhinitis was also present in 28 patients. The diagnosis of asthma was based on clinical criteria that include history and clinical evidence of airflow obstruction. Ten potential allergens (Bermuda grass, Olive tree, Parietaria, Alternaria, Cat hair dander, Dog hair dander, Mite DPT, Mugwort, Birch tree and Timothy grass) common to the Mediterranean area, were utilized. Twenty-five of 60 specimens were seropositive. Mite DPT was the allergen identified in 16 of the 25 seropositive specimens. Six of the 25 seropositive specimens reacted with more than one allergen. This may be due to the existence of similar antigenic determinant groups in the allergens used. There was no correlation between the occurrence of rhinitis in addition to asthma on one hand and the identified allergen on the other. Sixteen of the 25 seropositive patients were female. This observation is believed to be related to their occupation. Dog hair dander was identified as the allergen in 1 of the 25 seropositive patients. The low figure obtained was expected because keeping house pets is not a common practice in Lebanon. The 35 seronegative patients may belong to the intrinsic asthma group or the causative allergen in each case was not one of the 10 allergens used in this study. These results indicate that the house dust mite appears to be the most common allergen in the Lebanese asthmatic group studied.

Rapid laboratory confirmation of human brucellosis by PCR analysis of a target sequence on the 31-kilodalton Brucella antigen DNA.

We developed a PCR-based assay for the rapid and specific laboratory diagnosis of human brucellosis directly from whole blood. Specimens were collected in EDTA tubes from 17 patients with acute serologic brucellosis and 3 patients with chronic relapsing brucellosis as determined by serologic tests and the patient's clinical picture. DNA was extracted from peripheral mononuclear cells obtained from the blood of patients with brucellosis and control individuals. Specific primers for the PCR amplification of a 223-bp region on the sequence encoding the 31-kDa immunogenic Brucella abortus protein (BCSP 31) were used. All amplicons had the expected size of 223 bp. The specificity of amplification was determined by Southern hybridization and restriction endonuclease analysis. DNA extracted from blood taken from 30 healthy individuals as well as from 9 patients with typhoid fever did not show any amplification with the primers used. The test proved to be rapid and specific for the laboratory confirmation of acute human brucellosis. Further studies must be conducted to assess the utility of this test on additional patients with chronic relapsing brucellosis as well as patients under treatment.

Bone marrow colony-stimulating factor and tumor resistance-enhancing activity of postendotoxin mouse sera.

The passive transfer of postendotoxin mouse serum could enhance nonspecific resistance to the development of TA3-Ha transplantable ascites tumor in mice. The postendotoxin serum was not directly cytotoxic to TA3-Ha tumor cells in vitro, nor did it contain significant amounts of residual endotoxin, but it was rich in colony-stimulating factors (CSFs). High-titer CSF serum could be induced by endotoxic lipopolysaccharide (LPS). Nonendotoxic, lipid-free, and polysaccharide-rich hydrolytic breakdown product of LPS (called PS) was less potent but still active in CSF induction. There was a correlation between the level of CSF stimulation and the capacity of the sera to transfer tumor resistance (TUR). Those LPS preparations that had the highest CSF-inducing capacity were the most potent in TUR enhancement. Suppression of CSF production by treatment with theophylline or epinephrine, enhancers of cyclic AMP/cyclic GMP ratios, lowered the enhancement of TUR by endotoxic LPS. The infection of serum donor mice with bacillus Calmette-Guérin (BCG) 18 days prior to LPS treatment gave the highest serum CSF levels and the most potent TUR-inducing serum preparation. Even more notable was the finding that the nontoxic PS preparation could replace toxic LPS in the above BCG-LPS system. The serum harvested from BCG-infected mice 2 hr after PS injection was similarly effective in the passive transfer of TUR.

Salmonella agona isolated from fish meal and a Salmonella strain isolated from shrimps in Lebanon.

Salmonella agona was isolated from an imported fish meal specimen and a Salmonella strain not listed in the Kauffmann-White Scheme was isolated from a shrimp specimen obtained from the Mediterranean coast of Lebanon. The biochemical and serological properties of the S. agona fish meal strain was identical to a standard strain. The serotype of the shrimp strain was O13,22 Vi. With the exception of hydrogen sulfide production the biochemical properties of the shrimp strain were similar to S. agona.

The bacterial flora of fruits and vegetables in Lebanon and the effect of washing on the bacterial content.

Washed and unwashed vegetables and fruit specimens including radish, lettuce, mint, carrots, parsley, strawberries, green almond, akadinya, green-gages, cherries, plums, peaches, pears, and apples were investigated for their bacterial content. Tested specimens had a high content of bacteria belonging to the genera Enterobacter, Citrobacter, Klebsiella, Proteus, Pseudomonas, Providencia, Escherichia, Staphylococcus, and Salmonella. The washing procedure followed was effective in reducing the number of bacteria, but did not eliminate them. Enterobacter agglomerans was present in most specimens tested, and 11 out of 28 E. coli isolates were serotypable and may be enterotoxigenic or enteropathogenic. These findings are of concern in view of the fact that food-borne illnesses including "Traveler's diarrhea" are common in Lebanon.

Neutralization of bacteria- and endotoxin-induced hypotension by lipoprotein-free human serum.

Normal human serum and a fraction rich in lipoprotein, Cohn fraction IV1, have been shown in previous studies to detoxify native endotoxin by decreasing lethality for mice, fever in rabbits, and by the alteration of the characteristic endotoxin-anti-endotoxin precipitin pattern in gels. These studies are extended herein and document the ability of normal human serum and fraction IV1 to neutralize the induction of hypotension in rabbits by viable gram-negative bacilli. Further fractionation of serum, using an ultracentrifugal flotation method for producing lipoprotein-free human serum and purified high-density lipoproteins, revealed the lipoprotein-free fraction to be capable of inhibiting endotoxin hypotensive activity and to alter diffusion of endotoxin in gels. On the other hand, the purified high-density lipoproteins failed to negate either activity.

Cellular and humoral immunity in subacute sclerosing panencephalitis.

Cellular and humoral immunity was studied in 26 patients with subacute sclerosing panencephalitis. Results were compared with those of 14 normal controls and 11 patients suffering from other neurological disorders. It was shown that cellular and humoral immune responses are adequate in subacute sclerosing panencephalitis. The persistently elevated levels of serum immunoglobulin G (IgG) and IgA indicated a persistent infection, and their progressive rise in later stages correlated with the progressive nature of the illness. IgG progressively increased with the clinical stage in the cerebrospinal fluid unaccompanied by a corresponding rise in the measles antibody titer. This suggests that antigenic determinants other than those tested play a role in the production of IgG in the cerebrospinal fluid. The progressive increase in the ratio of cerebrospinal fluid to serum IgG with the advance of the disease suggests synthesis of IgG locally in the central nervous system. Elevated measles antibody titer in serum and cerebrospinal fluid is a consistent aid in the diagnosis of subacute sclerosing panencephalitis. It is more specific in cerebrospinal fluid than in serum. Its level did not vary significantly with the clinical stages or duration of illness. Depressed serum complement activity has been detected in some subacute sclerosing panencephalitis patients in whom serum levels of the third and fourth components of the complement were normal.

Immunization of mice against Salmonella typhimurium using different DNA preparations.

Groups of female BALB/c mice were given primary and booster injections of whole genomic DNA extracted from S. typhimurium, P. aeruginosa, or S. aureus. Other groups of mice were immunized in a similar manner with the 1.57kb fragment of the mouse virulence gene (mviA), pTargeT vector (plasmid DNA)/1.57kb construct, pTargeT vector, or saline. Mice in all groups were challenged intraperitoneally with 100 LD50 of S. typhimurium. The bacterial genomic DNA was extracted using the Pure Gene extraction kit. Specific primers were used to amplify the 1.57kb fragment by PCR. The pTargeT Mammalian Expression Vector System was used to prepare the plasmid/ 1.57kb construct. Bacterial genomic DNA extracted from P. aeruginosa and S. aureus appeared to induce non-specific resistance in mice. Specific, in addition to non-specific resistance appeared to be induced when genomic DNA from S. typhimurium was used. There was a prolongation of survival in the groups of mice that received either the 1.57kb fragment or the pTargeT vector/1.57kb construct and 16.67% and 33.34% respectively, of mice in each group survived at 40 days post challenge. None of the mice in the saline control group survived by day 7 post challenge. It is suggested that the non-specific resistance observed in this study might have been due to the adjuvant effect of the non-methylated CpG and other immunostimulatory motifs in bacterial DNA. Specific resistance obtained when genomic DNA from S. typhimurium was used might have been due to minute antigenic contamination, or virulence factor genes other than the mviA gene, might have been expressed in the host, which induced specific immunity.