Haloferax volcanii for biotechnology applications: challenges, current state and perspectives

Haloferax volcanii is an obligate halophilic archaeon with its origin in the Dead Sea. Simple laboratory culture conditions and a wide range of genetic tools have made it a model organism for studying haloarchaeal cell biology. Halophilic enzymes of potential interest to biotechnology have opened up the application of this organism in biocatalysis, bioremediation, nanobiotechnology, bioplastics and the biofuel industry. Functionally active halophilic proteins can be easily expressed in a halophilic environment, and an extensive genetic toolkit with options for regulated protein overexpression has allowed the purification of biotechnologically important enzymes from different halophiles in H. volcanii. However, corrosion mediated damage caused to stainless-steel bioreactors by high salt concentrations and a tendency to form biofilms when cultured in high volume are some of the challenges of applying H. volcanii in biotechnology. The ability to employ expressed active proteins in immobilized cells within a porous biocompatible matrix offers new avenues for exploiting H. volcanii in biotechnology. This review critically evaluates the various application potentials, challenges and toolkits available for using this extreme halophilic organism in biotechnology.

Haloferax volcanii as immobilised whole cell biocatalyst: new applications for halophilic systems

Enzyme-mediated synthesis of pharmaceutical compounds is a 'green' alternative to traditional synthetic chemistry, and microbial engineering opens up the possibility of using whole cells as mini-factories. Whole-cell biocatalysis reduces cost by eliminating expensive enzyme purification and cofactor addition steps, as well as resulting in increased enzyme stability. Haloferax volcanii is a model halophilic archaeon encoding highly salt and organic solvent tolerant enzymes such as alcohol dehydrogenase (HvADH2), which catalyses the reduction of aldehydes and ketone in the presence of NADPH/NADH cofactor. A H. volcanii strain for constitutive HvADH2 expression was generated using a strong synthetic promoter (p.syn). The strain was immobilised in calcium alginate beads and repeatedly used as a whole-cell biocatalyst. The reduction of acetophenone, used as test substrate, was very successful and high yields were detected from immobilised whole cells over repeated biotransformation cycles. The immobilised H. volcanii retained stability and high product yields after 1 month of storage at room temperature. This newly developed system offers halophilic enzyme expression in its native environment, high product yield, stability and reusability without the addition of any expensive NADPH/NADH cofactor. This is the first report of whole cell-mediated biocatalysis by the halophilic archaeon H. volcanii.

In-vitro activity of nisin against clinical isolates of Clostridium difficile

Nisin is a cationic peptide produced by Lactococcus lactis. Its activity against clinical isolates of Clostridium difficile was compared to that of vancomycin and metronidazole by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill studies. Nisin was more active than the other agents, with a MIC90 of 0.256 mg/L and strong bactericidal activity. Nisin may be a promising agent for the management of C. difficile associated diarrhea.

Lumbar pain in a married couple who likes cheese: brucella strikes again!

A 69-year-old man living in Florence reported fever and acute lumbar pain one month after transurethral resection of a superficial transitional cell carcinoma of the bladder. The radionuclide bone scan suggested metastatic lesions of the L3-L4 vertebrae. However cobalt treatment was ineffective. A bone biopsy of L4 showed an inflammatory pattern and antibiotic therapy was started which did not produce any clinical improvement. Six months after the onset of the back pain brucellar spondylitis was serologically diagnosed and treatment with doxycycline and streptomycin produced a significant clinical and radiological improvement. After 2 months the patient's wife presented with fever and lumbar pain, and brucellar spondylitis was diagnosed as well. An extensive epidemiological examination revealed that 8 months earlier the family had eaten unpasteurized goat cheese and serological examination of the entire family showed that 3 out of 4 members had significant titres of brucellar antibodies. Finally it was discovered that 4 months after consuming the cheese the third infected subject experienced an episode of epidydimoorchitis for which no diagnosis and effective treatment was found. This family cluster of brucellar infection indicates that a high degree of suspicion in the diagnosis of brucellosis is necessary even in non-endemic areas, to reduce the delay in the diagnosis and treatment of the disease and to prevent the occurrence of complications that may prove difficult to treat.

[The role of linezolid in the therapy of infections caused by multiresistant gram-positive cocci]

Gram-positive cocci are becoming more and more common agents of nasocomial infections, primarily enterococci and staphylococci in the field of surgical site and bloodstream infection. At the same time, the frequency of multiresistant enterococci and methicillin-resistant staphylococci has increased, whereas glycopeptide-resistant enterococcal strains and, recently, staphylococci with reduced susceptibility to glycopeptides have appeared, so making the use of glycopeptides as the "last-chance drugs" ineffective. Under those circumstances, the synthesis of new potent antibiotics, such as oxazolidinones, is both desirable and welcome. Linezolid possesses a high activity against all multiresistant gram-positive cocci, favourable pharmacokinetics, a good safety profile, a complete bioavailability after and administration permitting switch therapy, a low capacity of inducing resistance, and both clinical and microbiologic efficacy as demonstrated by a number of clinical trials conducted on thousands of patients. So, linezolid is an important therapeutic option in the treatment of infections caused by multiresistant enterococcal and staphylococcal strains.

Evaluation of a rapid immunochromatographic test for the serologic diagnosis of tuberculosis in Italy

OBJECTIVE

To determine specificity, sensitivity and predictive values of a rapid immunochromatographic assay (ICT tuberculosis) for the diagnosis of tuberculosis (TB) in an Italian clinical setting, and to identify tentative new guidance for the interpretation of test results.

METHODS

The ICT tuberculosis test is an immunochromatographic test based on the detection of IgG antibodies directed against five highly purified antigens secreted by Mycobacterium tuberculosis during active growth. Sera from 60 patients with active pulmonary (48 sputum smear-positive and six sputum smear-negative cases) and extrapulmonary (six cases) TB were obtained. Personal, anamnestic and clinical data were investigated and recorded for each patient. The control groups comprised 156 subjects: 40 healthy individuals, half of them Mycobacterium bovis BCG-vaccinated, and 116 patients with mycobacterial diseases other than TB (five cases), with nonmycobacterial lung diseases (30 cases), with nonmycobacterial nonlung diseases (30 cases), with nonmycobacterial diseases and rheumatoid factors positivity (30 cases), and with asymptomatic HIV infection (21 cases). For 21 individuals the test was simultaneously performed with both serum and whole blood sample. Each positive result of the ICT test was reported with regard to the number (1-4), position (A, B, C, D) and color intensity (+ to ++++) of the evidenced lines in order to assess the quality of the antibody response.

RESULTS

The overall sensitivity and specificity were 56.7% and 90.4%, respectively. The sensitivity for pulmonary TB patients was 61.1% (66.7% for smear-positive and 16.7% for smear-negative cases) and 16.7% for extrapulmonary TB patients. The difference between ICT results in pulmonary TB patients and control subjects was statistically significant (P < 0.0001). The analysis of the positive ICT tests revealed that samples with strong color intensity (>/=++) and specific antibodies bound to antigens immobilized on line D were significantly more frequent in TB patients than in controls (P = 0.001 and P= 0.027, respectively). ICT test results with the presence of at least three visible lines were more often observed in the TB patients than in controls, although not reaching statistical significance (P = 0.052). No difference was observed between the results of the ICT test performed both on serum and whole blood sample.

CONCLUSIONS

The ICT tuberculosis test was confirmed to be rapid and easy to perform without requiring special equipment, both on serum and whole blood sample. Our data, in accordance with those obtained in a previous study conducted in extra-European countries, confirmed higher sensitivities for the smear-positive TB patients than for the smear-negative TB patients, and for pulmonary TB patients than for the extrapulmonary TB patients. Data obtained on the quality of antibody response in the ICT positive samples, might be used to improve the performance of the test.

[New treatment perspectives for community acquired infections]

Respiratory and urinary tract infections, of great importance both for their high incidence and for their potential severity (particularly in the lower respiratory tract), represent one of the problems that doctors have to deal with in clinical practice. In outpatients the antibiotic prescription for such pathologies is most often empirical, and needs to consider the local epidemiology, including the incidence of antibiotic resistance, as well as the characteristics of drugs to be prescribed. From this point of view, the lack of drugs with a wide antibacterial spectrum, covering both classical and atypical bacteria, is now overcome by new fluoroquinolones, as levofloxacin. Its characteristics, such as the antibacterial activity extended to Gram positive (particularly S. pneumoniae), the pharmacokinetic profile allowing once daily administration and proper switch therapy, and safety, have been confirmed in wide international clinical studies and make levofloxacin an innovative drug with great potential

Streptococcus pneumoniae as an agent of nosocomial infection: treatment in the era of penicillin-resistant strains

Streptococcus pneumoniae is a well-known agent of community-acquired infections such as sinusitis, otitis media, pneumonia, bacterial meningitis, bacteremia and acute exacerbations of chronic bronchitis. However, the role of S. pneumoniae as a cause of nosocomial infections of respiratory tract, bloodstream and central nervous system is more and more recognized, primarily in high-risk patients with depression of their immune function. Therapy of pneumococcal infections is made difficult by the emergence and spread of bacterial resistance to penicillin and other beta-lactams as well as to a number of antimicrobials such as macrolides, chloramphenicol, tetracyclines and sulfonamides. This epidemiological situation is a cause for concern world-wide, but it primarily affects some European countries, North America, South Africa and the Far East. The main consequence on therapeutic grounds is that in severe infections such as bacterial meningitis, the addition of vancomycin to a third-generation cephalosporin is advisable while awaiting laboratory test results, even in areas with low prevalence of penicillin-resistant pneumococci. However, a beta-lactam agent can also be a valid choice in the presence of potentially lethal infections such as pneumonia or in the case of penicillin intermediately resistant isolates. In recent years, new alternative molecules have been introduced into clinical practice for therapy of infections caused by penicillin-resistant pneumococci. In both in vivo and in vitro studies, drugs of the classes of fluoroquinolones (levofloxacin, moxifloxacin, gatifloxacin), streptogramins (quinupristin/dalfopristin) and oxazolidinones (linezolid) have shown good microbiologic and clinical efficacy against penicillin-resistant pneumococci. In this era of world-wide spread of penicillin-resistant pneumococci, use of polysaccaride or conjugated vaccines is highly recommended.

Epilepsy, cysticercosis, and toxocariasis: a population-based case-control study in rural Bolivia

OBJECTIVE

To assess the relationship between epilepsy and infection with Taenia solium and Toxocara canis with a case-control study, in the rural area of the Cordillera Province, Bolivia.

METHODS

A preliminary two-phase door-to-door prevalence survey determined the prevalence of epilepsy and identified cases and control subjects. At least two control subjects per case were selected, matching on sex, age, and community of residence. Cases and control subjects were assessed serologically for antibodies against T. canis by ELISA and against T. solium by enzyme-linked immunoelectrotransfer blot (EITB).

RESULTS

The prevalence survey found 130 confirmed cases of epilepsy, of which 113 were eligible for the case-control study (59 partial seizures and 54 generalized seizures). Two hundred thirty-three control subjects were selected. Multivariable analysis for a matched case-control study was carried out. There was an association between EITB positivity for T. solium and epilepsy with an OR of 1.85 (95% CI 0.99 to 3.4) for all cases. A stronger association was found in those with partial epilepsy with a late onset of disease (15 years and older), where the OR was 3.66 (95% CI 1.10 to 12.10). A positive association was also found with T. canis for all cases with an OR of 2.70 (95% CI 1.41 to 5.19). This increased for those with late-onset partial epilepsy to an OR of 18.22 (95% CI 2.10 to 158.10).

CONCLUSION

This finding suggests that both neurocysticercosis and toxocariasis may in part explain the higher prevalence of epilepsy, particularly partial epilepsy, in developing countries.

Infections in multiple myeloma

Multiple myeloma is a relatively rare but severe hematologic malignancy. Marked depression in production of normal immunoglobulins, mild neutropenia, and alkylant/steroid therapy or BMT/SCT all produce major suppression of the immune system in the totality of patients. Recurrent bacterial, fungal, and viral infections are an important cause of morbidity and the most common cause of death in these subjects. Prompt diagnosis and appropriate anti-infective chemotherapy are essential in order to reduce the risk of mortality.

Antistaphylococcal (MSSA, MRSA, MSSE, MRSE) antibiotics

S. aureus and coagulase-negative staphylococci such as S. epidermidis are important causes of infection of the bloodstream, cardiac valves, implanted devices, and skin, with repercussions on mortality and increased economic costs. Treatment of staphylococcal infections is made difficult by the increasing emergence of resistance to beta-lactams and other antimicrobials, including reduced susceptibility to glycopeptides. Penicillin must be used for infrequent penicillin-susceptible isolates, oxacillin and nafcillin are to be considered the major option for penicillin-resistant staphylococci, and glycopeptides are the drugs of choice for infections caused by methicillin-resistant strains. Co-trimoxazole, lincosamides, macrolides, tetracyclines, and fluoroquinolones are alternative agents, primarily in subjects allergic to beta-lactams. Newly introduced or experimental drugs, such as streptogramins (quinupristin-dalfopristin), oxazolidinones (linezolid), carbapenems (LY 333328), everninomicins (SCH 27899), and derivatives of tetracyclines (glycylcyclines), could be useful for therapy of infections caused by multiresistant staphylococci.

Clinical and microbiologic efficacy and safety profile of linezolid, a new oxazolidinone antibiotic

Gram-positive cocci are important causes of infection both in the community and in the hospital, with repercussions on mortality and increased economic costs. Treatment of these infections is made difficult by the increasing emergence of multi-resistant organisms, primarily among Gram-positive cocci, such as vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci, and penicillin-resistant pneumococci. Linezolid, a member of the new class of synthetic antimicrobials named oxazolidinones, has several favourable characteristics including high activity against multiresistant Gram-positive cocci. In a number of clinical trials, linezolid showed good clinical and microbiologic efficacy in the therapy of infections caused by these organisms. It can be considered a valid option for treating both community- and hospital-acquired infections due to multiresistant Gram-positive cocci.

A neuroepidemiological survey in rural Bolivia: background and methods

A door-to-door survey was carried out in rural areas of the Cordillera province, Santa Cruz Department, Bolivia. A cluster sample of 10,124 inhabitants was selected. The aim was to determine the prevalence of the most common neurological diseases (epilepsy, stroke, parkinsonism and peripheral neuropathy) in this population using a modification of the World Health Organization screening instrument. 1,130 subjects screened positive and were then investigated by neurologists. In this paper we describe the background and methods of the survey and the characteristics of the population.

Distribution and antibiotic resistance of isolates from lower respiratory tract and blood cultures from patients in three Italian intensive care units: a 2-year comparison

The distribution and antibiotic resistance of major pathogens isolated from patients in ICUs were studied by three Italian microbiological laboratories. Consecutive aerobic strains were collected over two different time periods from protected brushing bronchoscopy, broncho-alveolar lavage and blood cultures. A total of 420 strains were isolated during the first period (47.3% gram-negative and 52.7% gram-positive) and 412 over the second period (50.5% gram-negative and 49.5% gram-positive). Pseudomonas aeruginosa was the most frequently isolated organism from the respiratory tract followed by Staphylococcus aureus. Methicillin resistance was 47.9 and 44.5% in S. aureus and 63.0 and 65.1% in coagulase-negative staphylococci over the two periods. No glycopeptide-resistance was found in gram-positive organisms. Ceftazidime-resistance in Klebsiella pneumoniae was very high.

Nosocomial bacterial and fungal meningitis in children; an eight year national survey reporting 101 cases. Pediatric Nosocomial Meningitis Study Group

One hundred and one cases of nosocomial meningitis in children from a national survey over 8 years have been analyzed for risk factors and outcome. From 101 cases, 115 organisms were isolated. Seventy six were Gram-positive bacteria, 29 were Gram-negative and there were ten fungal isolates. Major risk factors for acquisition of nosocomial meningitis were neurosurgery (70.2%), ventriculoperitoneal shunt (42.9%), prior therapy with broad spectrum antibiotics (64.1%), central venous catheter (94.5%), premature neonates with very low birth weight (32.8%) and total parenteral nutrition (68.8%). Overall attributable mortality was 14. 9%; in bacterial infection it was 13.2% and in fungal nosocomial meningitis, 30.0%. Higher mortality was significantly related to perinatal pathology with CNS abnormality, prematurity polymicrobial infection with Enterobacteriaceae and concomitant bacteraemia. Prematurity in neonates, very low birth weight and infection with Enterobacteriaceae were significantly associated with a worse outcome.

Multicenter randomized trial comparing meropenem (1.5 g daily) and imipenem/cilastatin (2 g daily) in the hospital treatment of community-acquired pneumonia

An open, multicenter study with 144 patients, aged between 18 and 94 years, was performed to compare the efficacy and safety of meropenem with imipenem/cilastatin in the hospital treatment of community-acquired pneumonia. Patients were randomized to receive either intravenous meropenem (500 mg every 8 h) or intravenous imipenem/cilastatin (1,000 mg every 12 h). The primary end point was considered to be clinical efficacy and the secondary end points were bacteriological response and safety assessment. At the end of therapy, cure or improvement in signs and symptoms as a satisfactory clinical response was observed in 57 of 64 (89.1%) meropenem-treated patients and in 60 of 66 (90.9%) imipenem/cilastatin patients. The mean duration of treatment was 10 days for meropenem and 9.7 days for imipenem/cilastatin. In patients who were followed up for weeks 2-4, the response was satisfactory (100%) for both treatments. A satisfactory bacteriological response, defined as either presumed or confirmed eradication of all pathogens, was found in eight patients who had received meropenem and in 14 patients who had received imipenem/cilastatin. Response was considered satisfactory in 100% of the meropenem group and in 92.9% of the imipenem/cilastatin group and at follow-up, it was 100% for both treatments. Drug-related adverse events were reported in three (4.2%) meropenem-treated patients and in eight (11.0%) imipenem/cilastatin-treated patients. None of these events was classified as serious. The results of this study show that the clinical and bacteriological efficacy and tolerability of meropenem (500 mg every 8 h) are similar to that of imipenem/cilastatin (1,000 mg every 12 h) in the hospital treatment of community-acquired pneumonia.

Antibiotic Resistance in Community-Acquired Pulmonary Pathogens

Among infectious diseases, pneumonia is still the ;;captain of the men of death.'' Etiologic diagnosis is often unreliable; consequently, clinicians must know epidemiology of community-acquired pneumonia for optimizing empiric antibiotic therapy. In recent years, all major pulmonary pathogens have become more and more resistant to conventional antibiotics. Penicillin-resistant and even multiresistant pneumococci have spread worldwide, but primarily in the United States, some European countries, South Africa, and the Far East. A similar trend is evidenced by ampicillin-resistant Hemophilus influenzae, whereas Moraxella catarrhalis almost invariably produces beta-lactamases. The widening of methicillin-resistant Staphylococcus aureus from hospitals to the community may be the new reality of the 1990s. Increasing erythromycin resistance of Streptococcus pyogenes requires beta-lactam therapy. The spread of both cromosomally and plasmid-mediated beta-lactamases makes treatment of infections caused by gram-negative enterobacilli more difficult. Bacterial resistance creates a challenge for clinicians from the viewpoint of correct and successful management of patients with community-acquired pneumonia.

Prevalence of epilepsy in rural Bolivia: a door-to-door survey

OBJECTIVE

To carry out a door-to-door survey in rural areas of the Cordillera Province, Santa Cruz Department, Bolivia, to determine the prevalence of neurologic diseases (epilepsy, stroke, parkinsonism, and peripheral neuropathy) in a sample of approximately 10,000 inhabitants.

METHODS

A team of nondoctor health workers administered a standard screening instrument for neurologic diseases-a slightly modified version of the World Health Organization protocol. All subjects found positive during the screening underwent a neurologic examination.

RESULTS

On screening, the authors found 1,130 positive subjects, of whom 1,027 were then investigated by neurologists. On the basis of the definition proposed by the International League Against Epilepsy, we detected 124 epileptic patients (prevalence, 12.3/1,000), 112 of whom had active epilepsy (prevalence, 11.1/1,000) on the prevalence day (November 1, 1994). Peak age-specific prevalence occurred in the 15 to 24-year age group (20.4/1,000). Sex-specific prevalence was higher in women (13.1/1,000) than men (11.4/1,000). Eighty-nine patients (71.8%) underwent a standard EEG recording. Considering both EEG and clinical data, partial seizures were the most common type (53.2%) based on the classification of the International League Against Epilepsy. The mean age at onset was 20.7 years for partial seizures and 13.6 years for generalized seizures. Only 10.5% of patients had received specific treatment for more than 2 months of their life.

CONCLUSION

This report on epilepsy prevalence in Bolivia confirms that epilepsy is a major health problem in rural areas of developing countries.

Prevalence of antibodies against hepatitis A and E viruses among rural populations of the Chaco region, south-eastern Bolivia

We conducted a cross-sectional study to determine the seroprevalence of antibodies against hepatitis A and hepatitis E viruses (HAV and HEV) in the population of two rural areas, Camiri and Villa Montes, of the Chaco region, south-eastern Bolivia. HAV antibodies were detected in 461 (94.1%) of 490 serum samples tested, not differing significantly between sexes and study areas. The HAV seropositivity rate (64.7%) was high even in the youngest age group (1-5 years). The prevalence of HEV was 7.3%, with no significant differences between sexes. The prevalence of HEV antibodies in the population of the Camiri area (10.4%) was significantly higher than in the Villa Montes area (4.4%), possibly due to the better quality of drinking water in the Villa Montes area. In the population </= 30 years of age, the HEV seropositivity rate (4.4%) was significantly lower than in the >/= 31 year-old group. This is consistent with findings in other countries. This is the first report of the prevalence of HEV infection in Bolivia.

Skeletal tuberculosis and other granulomatous infections

After several decades of steadily decreasing incidence, tuberculosis has had a resurgence in the past 15 years, not only in the lungs, but also in extrapulmonary sites. This is primarily a result of the AIDS pandemic, considering that HIV specifically affects cellular immunity, which is the first-line defence against tuberculosis. The generally non-specific clinical and radiological patterns of skeletal tuberculosis make it similar to other bacterial, fungal, inflammatory and neoplastic diseases of the bones and joints. Physicians must not omit tuberculosis in the differential diagnosis of any osteo-articular inflammatory process so that specific treatment may be initiated as soon as possible. Anti-tuberculous therapy is beset by important factors that limit its efficacy, such as the emergence of drug toxicity and of resistant or multiresistant mycobacterial strains. Surgical treatment may be indicated in selected cases where medical therapy alone is not sufficient to eradicate the problem.

[Antibodies against Trichinella spiralis in the rural population of the Province of Cordillera, Bolivia]

A seroepidemiological study was conducted to determine the prevalence of antibodies to Trichinella spiralis among rural residents of Cordillera province, Santa Cruz Department, Bolivia. Using the enzyme-linked immunosorbent assay (ELISA), 234 serum samples were examined, and antibodies were detected in seven of the samples (3%). The results document for the first time the presence of human infestation with Trichinella in Bolivia and suggest the need to strengthen trichinelosis surveillance in the municipal slaughterhouses, to prevent the clandestine slaughter of animals, and particularly to ensure that residents and meat producers in the area become aware of the dangers of this zoonosis.

Treatment of otitis media

Otitis media is a very common reason for the prescription of antibiotics in children. Antimicrobial therapy is mostly empirical, based on the knowledge of the frequency and susceptibility patterns of causative pathogens and of the penetration and other pharmacokinetic properties of several oral antibiotics. Pharmacoeconomic considerations must also be taken into account.

Is Streptococcus pneumoniae a nosocomially acquired pathogen?

Streptococcus pneumoniae is most prominently a major cause of community-acquired infections of the respiratory tract, central nervous system, and bloodstream, but there is an increasing interest in its role in the epidemiology of hospital-acquired infections. Penicillin-resistant pneumococcal strains appeared 3 decades ago and now are present worldwide, often displaying multiple resistance due to antibiotic selective pressure. Horizontal spread can cause either sporadic cases or hospital outbreaks, primarily in younger children and elderly patients. Pneumococcal transmission from one patient to another can be documented by polymerase chain reaction or pulsed-field gel electrophoresis typing. Nosocomial acquisition of infection, along with pediatric age, previous hospitalization, and previous beta-lactam therapy, are the main risk factors significantly associated with penicillin-resistant pneumococcal infections. Nosocomial acquisition also is associated with higher mortality from pneumococcal disease. The importance of penicillin resistance as a risk factor significantly associated with higher mortality from pneumococcal infection is found in some studies, but not in others. Mortality from pneumococcal pneumonia is approximately the same for human immunodeficiency virus (HIV)-infected patients without acquired immunodeficiency syndrome (AIDS) as for HIV-negative subjects, but it is significantly higher in AIDS patients. Penicillin-resistant strains are involved in the vast majority of hospital outbreaks, whether presenting as clinically manifest infection or a simple colonization. Pneumococcal vaccination is recommended universally in order to lower the incidence of invasive infection, although a number of problems can limit its effectiveness.

Urosepsis in the critical care unit

Critical care unit patients show a higher risk of developing a bloodstream infection than ward patients. The urinary tract is the main source of hospital-acquired secondary bloodstream infection. Nosocomial urinary tract infection is promoted by bladder catheterization in the vast majority of cases. Aerobic gram-negative bacilli are the prevalent agents of bloodstream infection secondary to a nosocomial urinary tract infection. Sepsis and septic shock are severe complications of these infections in the critical care patient. Management of patients with a septic process of urinary source calls for the combination of adequate life-supporting care, an appropriate antibiotic therapy, and innovative adjunctive measures. Accurate catheter care is the best measure to adopt for the prevention of urosepsis.

Tropical pulmonary eosinophilia. Report of a case

Tropical pulmonary eosinophilia (TPE) is an unusual manifestation of filarial infection, most commonly found in South-East Asia and caused by immunologic hyperresponsiveness to Wuchereria bancrofti and Brugia malayi. This report concerns a case of TPE in a 25-year-old Indian male who had been living in Italy for two years and was admitted to hospital with chest pain. Diethylcarbamazine therapy proved effective in rapidly eliminating symptoms and pulmonary abnormalities, as well as normalizing of laboratory findings.

Patterns of antimicrobial use and antimicrobial resistance among healthy children in Bolivia

OBJECTIVE

To determine the incidence of antimicrobial-resistant, nonpathogenic Escherichia coli among healthy children aged 6-72 months in Camiri town and a rural village, Javillo, in south-eastern Bolivia.

METHOD

A community-based survey: stool samples were obtained from 296 healthy children selected by modified cluster sampling in Camiri and all 25 eligible children in Javillo. E. coli isolates were tested for antimicrobial susceptibility according to the standard disc diffusion method. By a questionnaire survey of 12 pharmacies and by using simulated patients, we investigated the antimicrobial availability and the usage patterns in Camiri town.

RESULTS

In Camiri, over 90%, and in Javillo over 70% of children carried E. coli resistant to ampicillin, trimethoprim-sulphamethoxazole (TMP/SMX) or tetracycline. Overall, 63% of children carried E. coli with multiple resistance to ampicillin, TMP/SMX, tetracycline and chloramphenicol. In the simulated patients study, antimicrobials were dispensed inappropriately for 92% of adults and 40% of children with watery diarrhoea, and were under-prescribed for males with urethral discharge (67%) or females with fever and dysuria (58%). The dose and/or duration of antimicrobials dispensed was almost always too low.

CONCLUSION

Our study showed a disturbingly high prevalence of carriage of nonpathogenic E. coli resistant to antimicrobials. The prevalence of resistance to ampicillin and TMP/SMX was higher than that previously reported in developing countries. The existence of a large reservoir of resistance genes in healthy individuals in developing countries represents a threat to the success of antimicrobial therapy throughout the world. Programmes to improve rational and effective drug use in developing countries are urgently needed.

Serologic survey for antibodies to Borrelia burgdorferi in sheep, goats and dogs in Cordillera Province, Bolivia

A serosurvey for antibodies to Borrelia burgdorferi using an enzyme-linked immunosorbent assay (ELISA) was conducted on sheep, goat and dog serum samples collected in Cordillera Province, Bolivia, in 1992 Sera from 98 sheep, 218 goats and 43 dogs were tested. The observed seroprevalence in sheep and dogs was 0.0%, whereas the seropositivity rate for goat serum samples was 5.0%. Upon analysing 10 positive sera by Western immunoblotting, five reacted against the specific protein antigens and all of them met the criteria for positivity on the basis of immunoglobulin G (IgG) bands, indicating that goats in Cordillera Province were exposed to B. burgdorferi. These findings, which are further proof of the existence of B. burgdorferi infection in Bolivia, indicate the serologic analysis of goats as a suitable tool for Lyme borreliosis surveillance.

Serological survey of leptospiral infections in sheep, goats and dogs in Cordillera province, Bolivta

A serological survey for antibodies to Leptospira spp. was conducted on sheep, goat and dog serum samples collected in three localities in Cordillera province in the southern part of the Santa Cruz Department (Bolivia) in 1992. A total of 98 sheep, 218 goats and 43 dogs were tested against 29 leptospiral serovars using the microscopic agglutination test. At the time of blood collection all of the examined animals appeared healthy and presented no clinical sign suggestive of leptospirosis. Antibody prevalences, as determined by positive results at a 1:100 dilution or higher, was 14.3% in sheep, 19.7% in goats, and 14.0% in dogs. Agglutinins against six serovars (poi. shermani, pomona, canicola, javanica, djasiman) were found in positive animals. The highest serological prevalence in sheep and goats was recorded for serovar poi, followed by pomona in sheep and shermani in goats. Titres to shermani were the commonest in dogs. The results of this survey indicate that leptospiral infection is common in south-east Bolivia and that serovars of several serogroups concur in the etiology.

[Emerging pathogens in lower respiratory tract infections]

Pneumonia is one of the most important causes of death in industrialized countries where it is the infection with the overall highest mortality rate. In contrast to bacteremia, in which the cause of infection is readily established, the determination of the cause of acute pneumonia remains problematic. About half the patients requiring admission to the hospital do not have the cause of pneumonia diagnosed. The emergence of newer pathogens and the recognition of new presentations of older pathogens, however, have made it apparent that it will always be necessary to pursue aggressively an etiologic diagnosis in patients with pneumonia. This article briefly reviews some of new pathogens of lower respiratory tract infections that have become very important in the last years for their capability to determine severe clinical patterns, for their high frequency in some high-risk patient groups and for difficult diagnosis or treatment. Moreover we present new facets of the "old pathogens" of community-acquired pneumonia. Particularly we underline major changes occurred in the antibiotic-susceptibility of Streptococcus pneumoniae and Haemophilus influenzae.

[Gram positive microorganisms in urinary tract infections: epidemiology and therapy]

Urinary tract infections are the most frequent hospital acquired infections and represent one of the major problem in general practice. The predominant causative agents are enteric gram-negative bacteria. Nevertheless, the importance of gram-positive bacteria, particularly Staphylococcus aureus and Enterococcus, has progressively increased especially in nosocomial urinary tract infections. Such an increase is probably related to the indiscriminate use of beta-lactam antibiotics or to the growing number of susceptible patients (surgical procedures, immunodeficiency, ecc.) The therapeutic approach of community and hospital infections is different: while in the first case treatment is usually not difficult, the therapy for nosocomial urinary tract infections should be based on the results of antibiotic susceptibility tests since a multiantibiotic resistant microorganism is often involved.

In vitro activity of MDL 62,879 against gram-positive bacteria and Bacteroides species

The new thiazolyl peptide antibiotic MDL 62,879 (GE2270 A) showed excellent in vitro activity in testing against staphylococci and streptococci, with MIC90s ranging from 0.23 to 0.9 mg/l. It was very active against Clostridium difficile and Propionibacterium acnes (MIC90 0.06 mg/l in each case) and had variable activity against Bacteroides spp. MDL 62,879 had exceptionally good activity against Enterococcus faecalis, including against a collection of high-level aminoglycoside-resistant isolates where it had an MIC90 of 0.047. The antibiotic was bacteriostatic for enterococcal isolates but bactericidal for a methicillin-resistant isolate of Staphylococcus aureus.

Once-daily dosing regimen for aminoglycoside plus betalactam combination therapy of serious lower respiratory tract infections

Aminoglycosides are important antibacterial agents for treatment of serious gram-negative bacillary infections including lower respiratory tract infection. Once-daily aminoglycosides result in higher peak and lower trough plasma concentrations than conventional multiple daily dosing regimens; once-daily aminoglycoside therapy is equally effective, generally less toxic and much less expensive and therefore this regimen is more and more frequently used for treatment of suspected or confirmed gram-negative bacillary infections and of febrile episodes in neutropenic patients, in particular in combination with an appropriate betalactam antibiotic. Despite the lack of studies on this topic, once-daily aminoglycosides in combination with a betalactam agent can be used in subjects with lower respiratory tract infection, including patients with cystic fibrosis, in which tobramycin appears to be the aminoglycoside antibiotic of choice.

[Pathogenetic mechanisms responsible for producing a secondary immunodeficiency state]

Abnormalities of the immune response can be secondary to old age, to several pathologic conditions (i.e. diabetes mellitus, renal failure, solid and lymphohematologic neoplasias, leukopenia, malnutrition, autoimmune diseases, AIDS), to surgical stress or to burns, and to immunosuppressive therapies, both medical (corticosteroids, cytotoxic agents, antilymphocytic globulins) and surgical (splenectomy) as well as radiant (extensive radiotherapy). Old age can affect both humoral (reduced antibody synthesis) and cell-mediated (thymus involution, diminished ratio Th/Ts, depression of both delayed hypersensitivity reactions and cytotoxic activity of K cells) immune response. Hyponutrition, often observed in the elderly, adds a reduced production of secretory IgA, lysozyme and interferon, diminished complementary activity, phagocytosis defects, and vitamin deficits. Furthermore, in some chronic diseases we can observe reduced primary antibody response or depression of delayed hypersensitivity reactions (renal failure, neoplasias), changes in leukocyte functions (diabetes mellitus, leukemias and lymphomas) and, in particular in solid neoplasias, increased activity of Ts lymphocytes and the presence of circulating immunocomplexes. Changes in phagocytosis, opsonization and chemotaxis are typically seen in burns, whereas surgical stress can cause some inhibition of cell-mediated immunity. Finally, after splenectomy it is possible to observe an increased synthesis of IgA and IgG and, on the contrary, reduced production of IgM and properdin.

Prevalence of antibodies to Borrelia burgdorferi, Borrelia parkeri and Borrelia turicatae in human settlements of the Cordillera Province, Bolivia

A seroepidemiological study to determine the prevalence of human Lyme borreliosis and tick-borne relapsing fever was carried out in three communities (Camiri, Boyuibe and Gutierrez) of the Cordillera Province, Santa Cruz Department, south-eastern Bolivia. Anti-B. burgdorferi, anti-B. turicatae and anti-B. parkeri antibodies, tested by the indirect immunofluorescent assay (IFA), were detected in 10.8, 16.1 and 8.2% of the serum samples tested, and confirmed by IFA-ABS in 1.3, 1.3 and 1.0%, respectively. This is the first report of the presence of Lyme borreliosis and tick-borne relapsing fever in Bolivia. For Lyme borreliosis these findings represent a further datum to support its existence in South America.

Urinary tract infections in the city of Florence: epidemiological considerations over a twenty-year period

Our study of significant bacteriurias indicated that the worldwide shift in the etiology of infections also holds true for the Florence area. In a twenty-year period (1970-1990), we noted a decreased frequency of Gram-negative bacilli, particularly of the family Enterobacteriaceae, and a significant increase of Gram-positive cocci in urinary patients. This finding was observed both in hospital and in community-acquired cases in the male sex and only in nosocomial bacteriurias in the female sex. There was a reduced isolation of "classic" urinary pathogens such as Proteus mirabilis: its prevalence in hospital-acquired urinary tract infection (UTI) decreased from 16% in 1970 to 5% in 1990 both in males and in females. On the other hand, we noted an increase of "difficult" microorganisms such as enterococci and methicillin-resistant staphylococci, particularly in the male sex; in 1970 enterococci were occasionally isolated in males both from hospital and from community-acquired UTIs (3% and 5%, respectively), whereas in 1990, on the contrary, they were encountered much more frequently (19% in both cases).

Which prophylactic regimen for which surgical procedure?

For optimal prevention of infection subsequent to a surgical intervention, it is necessary to follow a series of general principles, including the classification of the type of surgical intervention, the characteristics of the antibiotic used, and the route and the time of its administration. Moreover, with reference to the different types of surgery, other factors assume importance: the etiology of the infection and the ability of the antibiotic to achieve adequate levels in the tissues at the beginning of the infective process. In general abdominal, biliary, and obstetric-gynecologic surgery, which covers many clean-contaminated and contaminated interventions for which antibiotic prophylaxis has been shown to be the most effective, the etiology is often mixed (aerobic and anaerobic flora) with a predominance of gram-negative microorganisms. Thus, an appropriate prophylactic regimen must consider a third-generation cephalosporin, such as cefotaxime, that is effective against most gram-negative bacteria, in particular against Klebsiella pneumoniae. Acylureido penicillins can also be used because of their activity against enterococci, gram-positive microorganisms that are also causes of infection in this area of surgical intervention. Combining an antimicrobial such as clindamycin or metronidazole, which are particularly active against anaerobes, may be recommended as well. In urologic surgery, most infections are caused by Enterobacteriaceae; in addition to the antimicrobial spectrum, the ability of the antibiotic to concentrate adequately in the urine and renal tissue must also be considered. Beta-lactam antibiotics are the agents of choice, in particular, third-generation cephalosporins, aztreonam, and acylureido penicillins. In cardiac, orthopedic, and partially in neurologic surgery, where most infections are due to gram-positive bacteria (primarily methicillin-resistant staphylococci), antibiotic prophylaxis should include a glycopeptide agent (teicoplanin, vancomycin). In the field of surgical prophylaxis, more experience has been accumulated with cefotaxime, used as a short-course regimen or as a convenient single dose, than with any other newer cephalosporin. Cefotaxime's broad spectrum of action provides coverage against most potential pathogens and, when used as a single dose, is both convenient and cost-effective.

Proposal of an improved score method for the diagnosis of pulmonary tuberculosis in childhood in developing countries

210 children aged less than 5 years, referred to the Arua Regional TB Centre (Uganda) for suspected pulmonary tuberculosis (PTB), were examined by anamnesis, clinical examination, Mantoux test, gastric washing, chest X-ray. The response to treatment criterion was applied to the patients treated. According to the score method suggested by Ghidey and Habte, 31 children were diagnosed as PTB patients. 30 of the 31 children with PTB tested positive for alcohol acid-fast bacilli (AAFB) in the aspirated juice. The Mantoux test and X-rays gave a minor contribution to diagnosis. The clinical results are commented. A statistical analysis was carried out to evaluate the role of gastric washing in the diagnosis of PTB in children under 5 years of age (sensitivity, 96.8%; specificity, 92.2%; positive predictive value, 68.2%; negative predictive value, 99.4%). The response to treatment was also evaluated. A modified enlarged score method (based on gastric washing and including response to treatment) is proposed to be applied in developing countries where chest X-ray and other facilities are often lacking.

Influence of teicoplanin on the chemiluminescence of phagocytosing human granulocytes

Teicoplanin is a new glycopeptide antibiotic that is structurally related to vancomycin. It is especially active against virtually all gram positive bacteria including methicillin-resistant staphylococci. The aim of this study was to evaluate the influence of teicoplanin on the phagocytosis of human neutrophils, using the chemiluminescence reaction method. We incubated three different concentrations (2, 5, 10 microg/ml) of teicoplanin for one and three hours with polymorphonuclear leukocytes of healthy human volunteers and then measured the chemiluminescence reaction during zymosan phagocytosis. The neutrophil function was not influenced by teicoplanin.