Activity of imipenem/relebactam against Enterobacterales and Pseudomonas aeruginosa in Spain. SMART 2016-2020

OBJECTIVE

To determine susceptibility to the novel β-lactam/β-lactamase inhibitor combination imipenem/relebactam in clinical isolates recovered from intra-abdominal (IAI), urinary (UTI), respiratory (RTI) and bloodstream (BSI) infections in the SMART (Study for Monitoring Antimicrobial Resistance Trends) study in SPAIN during 2016 - 2020.

METHODS

Broth microdilution MICs for imipenem/relebactam and comparators were determined by a central laboratory against isolates of Enterobacterales and Pseudomonas aeruginosa. MICs were interpreted using EUCAST-2021 breakpoints.

RESULTS

In total, 5,210 Enterobacterales and 1,418 P. aeruginosa clinical isolates were analyzed. Imipenem/relebactam inhibited 98.8% of Enterobacterales. Distinguishing by source of infection susceptibility was 99.1% in BSI, 99.2% in IAI, 97.9% in RTI, and 99.2% in UTI. Of intensive care unit isolates (ICU) 97.4% were susceptible and of non-ICU isolates 99.2% were susceptible. In Enterobacterales, activity against Class A, Class B and Class D carbapenemases was 96.2%, 15.4% and 73.2%, respectively. In P. aeruginosa, imipenem/relebactam was active in 92.2% of isolates. By source of infection it was 94.8% in BSI, 92.9% in IAI, 91.7% in RTI, and 93.1% in UTI. An 88.7% of ICU isolates and 93.6% of non-ICU isolates were susceptible to imipenem/relebactam. Imipenem/relebactam remained active against P. aeruginosa ceftazidime-resistant (76.3%), cefepime-resistant (73.6%), imipenem-resistant (71.5%) and piperacillin-resistant (78.7%) isolates. Of all multidrug-resistant or difficult-to-treat resistance P. aeruginosa isolates, 75.1% and 46.2%, respectively, were susceptible to imipenem/relebactam.

CONCLUSIONS

Imipenem/relebactam showed high rates of susceptibility in Enterobacterales and P. aeruginosa isolates from different sources of infection as well as depending on patients' location (ICU or non-ICU scenarios).

Antimicrobial activity of ceftolozane-tazobactam against Enterobacterales and Pseudomonas aeruginosa recovered during the Study for Monitoring Antimicrobial Resistance Trends (SMART) program in Spain (2016-2018)

OBJECTIVE

To analyse the susceptibility to ceftolozane-tazobactam and comparators in Enterobacterales and Pseudomonas aeruginosa isolates recovered from intraabdominal (IAI), urinary (UTI), respiratory (RTI) and bloodstream infection (BSI) in the SMART (Study for Monitoring Antimicrobial Resistance Trends) study.

METHODS

The susceptibility of 5,351 isolates collected in 11 Spanish hospitals (2016-2018) were analysed (EUCAST-2020 criteria) by broth microdilution and were phenotypically studied for the presence of extended-spectrum beta-lactamases (ESBL). Ceftolozane-tazobactam and/or carbapenem resistant isolates were genetically characterized for ESBL and carbapenemases.

RESULTS

Escherichia coli was the most frequent pathogen (49.3% IAI, 54.9% UTI, 16.7% RTI and 50% BSI), followed by Klebsiella pneumoniae (11.9%, 19.1%, 13.1% and 15.4%, respectively). P. aeruginosa was isolated in 9.3%, 5.6%, 32% and 9%, respectively. The frequency of isolates with ESBLs (2016-2017) was: 30.5% K. pneumoniae, 8.6% E. coli, 2.3% Klebsiella oxytoca and 0.7% Proteus mirabilis. Ceftolozane-tazobactam was very active against non-ESBL-(99.3% susceptible) and ESBL-(95.2%) producing E. coli being less active against K. pneumoniae (98% and 43.1%, respectively) isolates. CTX-M-15 was the most prevalent ESBL in E. coli (27.5%) and K. pneumoniae (51.9%) frequently associated with OXA-48-like carbapenemase. Overall, 93% of P. aeruginosa isolates were susceptible to ceftolozane-tazobactam, preserving this activity (>75%) in isolates resistant to other beta-lactams except in those resistant to meropenen or ceftazidime-avibactam. GES-5, PER-1, VIM-1/2 were the most prevalent enzymes in isolates resistant to ceftolozane-tazobactam.

CONCLUSIONS

Ceftolozane-tazobactam showed high activity rates against isolates recovered in the SMART study although it was affected in K. pneumoniae and P. aeruginosa isolates with ESBL and/or carbapenemases.

Antimicrobial susceptibility trends and evolution of isolates with extended spectrum β-lactamases among Gram-negative organisms recovered during the SMART study in Spain (2011-2015)

OBJECTIVE

The SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study monitors antimicrobial susceptibility and extended spectrum β-lactamases (ESBLs) in Gram-negative bacilli recovered from intra-abdominal infections (IAI).

METHODS

Antimicrobial susceptibility of 5,343 isolates from IAI recovered in 11 centres during the 2011-2015 SMART-Spain program was analysed by standard microdilution (EUCAST criteria) and compared with that from 2002-2010. ESBLs were phenotypically detected.

RESULTS

Escherichia coli, the most common isolate, significantly decreased in community acquired IAI (60.9% 2002-2010 vs. 56.1% 2011-2015, P=0.0003). It was followed in prevalence by Klebsiella pneumoniae that increased both in the community (8.9% vs. 10.8%, P=0.016) and nosocomial (9.2% vs. 10.8%, P=0.029) IAI and P. aeruginosa, which significantly increased in community acquired IAI (5.6% vs. 8.0%, P=0.0003). ESBLs were more prevalent in K. pneumoniae (16.3%) than in E. coli (9.5%) of nosocomial origin and were more frequently isolated from elderly patients (>60 years). Considering all Enterobacteriaceae, ertapenem (92.3-100%) and amikacin (95.5%-100%) were the most active antimicrobials. Ertapenem activity, unlike amoxicillin-clavulanate or piperacillin-tazobactam, remained virtually unchanged in ESBL (100%) and non-ESBL (98.8%) E. coli producers. Its activity decreased in ESBL-K. pneumoniae (74.7%) but was higher than that of amoxicillin-clavulanate (14.0%) and piperacillin-tazobactam (24.0%). Interestingly, ertapenem susceptibility was maintained in >60% of ESBL isolates that were resistant to amoxicillin-clavulanate, piperacillin-tazobactam or fluoroquinolones.

CONCLUSIONS

SMART-Spain results support current guidelines which include ertapenem as empiric treatment in mild-moderate community-acquired IAI, particularly with ESBL producers. These recommendations will need to be updated with the recently introduction of new antimicrobials.

Usefulness of PCR-RFLP coa gene for clonal classification of methicillin-resistant Staphylococcus aureus isolates in tertiary hospitals

One hundred and one methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates were classified into 10 genotypes based on their polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) coa pattern. PCR-RFLP coa patterns correlated with the clonal complex (CC) with the exception of CC5, which was related to 2 patterns (B and E). The PCR-RFLP coa gene technique provides a useful preliminary method to monitor variations in MRSA populations.

[Emergence of plasmid mediated AmpC β-lactamasas: Origin, importance, detection and therapeutical options]

AmpC β-lactamases can hydrolyze penicillins, oxyimino-, 7-α-methoxycephalosporins and monobactams. Susceptibility to cefepime or cefpirome is little affected and is unchanged for carbapenems. Originally such genes are thought to have been mobilized to mobile genetic elements from the chromosomal ampC genes from members of Enterobacteriaceae facilitating their spread and now they can appear in bacterial lacking or poorly expressing a chromosomal ampC gene. The prevalence of infection by plasmid mediated AmpC (pAmpC) varies depending on the type of enzyme and geographical location and blaCMY-2 is the most frequently detected worldwide. Typically, pAmpC producing isolates are associated with resistance to multiple antibiotics making the selection of an effective antibiotic difficult. Phenotypic and molecular methods to detect pAmpC are described and the role of different antibiotics in the treatment of these infections is examined. Surveillance studies about the evolution of this emerging resistant mechanism are important in clinical isolates. Evaluate the in vitro susceptibility of these isolates and the clinical efficacy of other therapeutic options is required.

A high-yielding serum-free, suspension cell culture process to manufacture recombinant adenoviral vectors for gene therapy

We have developed an efficient, reproducible, and scaleable cell culture process for a recombinant adenoviral vector expressing therapeutic transgenes for clinical trials. HEK 293 cells - which support the propagation of E1 deficient adenovirus - were first adapted to serum free media and suspension growth. Subsequent studies focused on the infection, virus production and harvest from suspension culture bioreactors. Future studies are planned to address the kinetics of adenovirus production in HEK 293 as well as in other cell lines.

Molecular mechanisms of quinolone resistance in clinical isolates of Aeromonas caviae and Aeromonas veronii bv. sobria

Mutations in quinolone targets were studied together with quinolone efflux pump activation and plasmid-mediated quinolone resistance determinants in nalidixic-acid-resistant isolates of Aeromonas caviae and Aeromonas veronii. Among 135 clinical Aeromonas spp. isolated from stools of patients with gastrointestinal symptoms, 40 nalidixic acid-resistant strains belonging to A. caviae and A. veronii were selected and their susceptibility to different quinolones (ciprofloxacin, norfloxacin, ofloxacin) further evaluated. Susceptibility to nalidixic acid and ciprofloxacin in the presence/absence of Phe- Arg-β-naphthylamide was also determined. The 16 nalidixic-acid-resistant strains identified as A. caviae were more resistant than the 24 A. veronii bv. sobria strains to ciprofloxacin, norfloxacin, and ofloxacin. All strains showed a mutation (single or double) at position 83 of the QRDR sequence of gyrA, with Ser-83 → Ile as the most frequent substitution. By contrast, no mutations were found at position 87 of gyrA. Double substitutions (GyrA-ParC) were detected in 50% of A. veronii bv. sobria isolates and in 43.75% of A. caviae strains. Both species showed decreases in the MICs of ciprofloxacin. A qnrS gene was found in an A. caviae strain. Thus, in the two species of nalidixic-acid-resistant Aeromonas isolates examined, resistance mediated by efflux pumps contributed only slightly to ciprofloxacin resistance. While two isolates were positive for the aac(6')-Ib gene, no -cr variants were detected.

Production of biomass and beta-D-galactosidase by Candida pseudotropicalis grown in continuous culture on whey

The production of biomass and beta-D-galactosidase by the lactose-utilizing yeast Candida pseudotropicalis NCYC 744 in whey medium was studied. Apparent optimization of growth conditions and medium was done in continuous culture. Optimal pH and temperature were 2.6 and 36-38 degrees C, respectively, Limitations in Cu, Zn, and possibly Mn were detected in deproteinized whey medium. Additions of tryptophan stimulated growth of the yeast. Under optimal conditions in medium supplemented with excess tryptophan, Cu, Zn, and Mn the maximum values obtained: yeast concentration, 4.6 g/L; yeast productivity, 1.4 g/L h (at D = 0.35 h(-1)); enzyme volumetric productivity, 2100 U/L h (at D = 0.25 h(-1)); maintenance coefficient, 5-10 mg lactose/g cell h; saturation constant (K(s)) for lactose, 4.76mM; maximum specific growth rate, (mu(max)), 0.47 h(-1). No significant increase in specific enzyme activity (U/mg cell) was observed after medium optimization evidencing the importance of regulatory controls in enzyme synthesis.

Plasmid-mediated QnrS2 determinant in an Aeromonas caviae isolate recovered from a patient with diarrhoea

A qnrS2 gene was identified in an Aeromonas caviae isolate (MICs of ciprofloxacin, norfloxacin and ofloxacin >32 mg/L) from a stool sample collected from a patient with gastroenteritis. The analysis of the gyrA and parC genes revealed amino acid substitutions Ser83-Ile and Ser80-Thr, respectively. In addition, five out of 41 nalidixic acid-resistant Aeromonas isolates studied (26 identified as Aeromonas veronii bv sobria and 15 identified as A. caviae) showed ciprofloxacin resistance. The identification of plasmid-mediated qnr genes outside of the Enterobacteriaceae underlines a possible diffusion of these resistance determinants among Gram-negative rods. This emphasizes the importance of monitoring the emergence of these determinants as well as their dissemination among the Aeromonadaceae.

In vitro activity of cefditoren and other antimicrobial agents against 288 Streptococcus pneumoniae and 220 Haemophilus influenzae clinical strains isolated in Zaragoza, Spain

In vitro cefditoren antimicrobial activity was tested against 288 Streptococcus pneumoniae and 220 Haemophilus influenzae clinical strains isolated in our hospital from January 2005 to May 2006 by agar dilution and broth microdilution method, respectively. MICs were also determined for 13 and 10 comparison drugs, respectively. The pneumococci tested comprised 113 (39.2%) penicillin susceptible, 91 (31.6%) penicillin intermediate, and 84 (29.2%) penicillin resistant. Cefditoren was the most active drug on the basis of the MICs (MIC(90)=0.5 microg/mL), followed by ceftriaxone and levofloxacin (MIC(90)=1 microg/mL). Cefditoren MICs ranged from 0.25 to 1 microg/mL for ceftriaxone-resistant isolates, with a modal MIC of 0.5 microg/mL and an MIC(90) of 1.0 microg/mL. No S. pneumoniae isolates evaluated in this study showed MICs to cefditoren higher than 1 microg/mL (MIC range, <or=0.015 to 1 microg/mL). Against penicillin-resistant pneumococci, the rank order of intrinsic activity (MIC(90), microg/mL) was cefditoren (0.5)<ceftriaxone (2.0)=cefotaxime (2.0)<amoxicillin/clavulanate (8.0)=amoxicillin (8.0)=cefuroxime (8.0). Among the 220 strains of H. influenzae, 42 (19.09%) produced a beta-lactamase (Hi beta+) and 3 (1.1%) were beta-lactamase (Hi beta-) negative but have reduced susceptibility to ampicillin (BLNAR). The most active drugs on the basis of MICs were cefditoren and levofloxacin, showing MIC(50) and MIC(90) values of 0.015/0.06 microg/mL. Cefditoren at concentration of 0.06 microg/mL inhibited all 3 BLNAR (ampicillin MICs >4 microg/mL). Against H. influenzae (Hi beta+), the rank order of intrinsic activity (MIC(90), microg/mL) was cefditoren (0.03) < cefixime (0.06)<ceftriaxone (0.12)=cefotaxime (0.12)<cefuroxime (1.0)<amoxicillin/clavulanate (2.0)<ampicillin (>8.0).

Correlation between the presence of symptoms and the Giardia duodenalis genotype

Clinical manifestations of Giardia duodenalis infection vary from asymptomatic infection to chronic diarrhoea. We study the correlation between the presence of symptoms and the G. duodenalis genotype in 108 patients with giardiasis. Patient age ranged from 2 to 72 years old. We found a correlation between assemblage AII and symptomatic infections, and between assemblage B and asymptomatic infections in the overall patient group and in patients less than five years of age. Nevertheless, if only patients of more than five years of age were considered, no statistically significant relationship between assemblage and symptomatic or asymptomatic Giardia infections was found. In these patients, host factors may affect the presence of clinical manifestations more than Giardia assemblage.

[Surveillance of commensal flora evolution and infections in neutropenic cancer patients submitted to chemoprophylaxis]

The evolution of the flora and its resistance to different antimicrobials in neutropenic patients submitted to high-dose chemotherapy with autologous blood stem-cell transplantation, and the relation of these findings to the etiology of the infections the patients developed was studied in order to evaluate the suitability of the chemoprophylaxis and the empirical antibiotic therapy used. Forty-one patients were analyzed in a period of 28 months. The chemoprophylaxis used was levofloxacin, fluconazole and acyclovir. The empirical sequential treatment was an initial administration of cefepime, followed by teicoplanin and amikacin. Cultures were done of nasal and pharyngeal smears, Hickman catheter and stools, 1 day before chemoprophylaxis started and then on days 5 and 9. In the case of fever, three sets of blood cultures and urine cultures were done and samples from areas related to the clinical condition were analyzed. Levofloxacin induced the selection of resistant strains or species in the flora and in the infectious agents. Fluconazole also selected resistant species in the flora. Seventeen infections were documented in eleven patients, produced by Gram-positive bacteria in thirteen cases (81.25%) and by Gram-negative bacteria in three (18.75%). The coagulase negative staphylococci and Enterococcus faecalis were the most frequent agents of infection. We identified on nine occasions the same microorganism in the flora and in the pathological product; this suggests its endogenous origin and supports the use of prospective cultures of the flora, monitoring the sensibility of the microorganisms isolated to the antimicrobials used in chemoprophylaxis and empirical treatment.

Evaluation of an immunochromatographic dip-strip test for the detection of Cryptosporidium oocysts in stool specimens

The study presented here examined the efficacy of a commercially available qualitative immunochromatographic assay for detecting Cryptosporidium oocysts in stool samples. A total of 75 samples were tested, including 50 positive for Cryptosporidium spp. by acid-fast stain, 20 positive for other parasites ( Blastocystis hominis, Endolimax nana, Entamoeba coli, Giardia lamblia, Ascaris lumbricoides, Strongyloides stercoralis and Trichuris trichiura), and five negative samples. The observed sensitivity was 98%, while specificity was 100%; the detection threshold was near 1000 oocysts/ml. Correctly diagnosed positive samples included Cryptosporidium parvum genotypes 1 and 2, whereas the single false-negative sample corresponded to a Cryptosporidium meleagridis infection.

[Antimicrobial resistance of clinical strains of Salmonella enterica isolated in Zaragoza]

In order to identify any changes in the incidence of Salmonella enterica serotypes and their resistance to a variety of antimicrobial agents, we conducted a retrospective study of all the strains isolated from stool samples at Hospital Clínico Universitario Lozano Blesa in Zaragoza from 1997 to 2000. We observed an increase in the number of isolates of Salmonella and Campylobacter and a decrease in other enteropathogens. Enteritidis was the most frequently isolated serotype (55.2%), showing an increasing tendency (from 44.1% in 1997 to 60.6% in 2000). Hadar, glostrup and virchow showed the highest rate of resistance to nalidixic acid. Enteritidis also showed an important increase in resistance to nalidixic acid (from 17.6% in 1997 to 41.4% in 2000). Typhimurium showed the highest resistance levels to ampicillin, chloramphenicol and cotrimoxazole. No resistance to fluoroquinolones or to cefotaxime was detected, with the exception of 0.5% of the S. enteritidis strains, which showed resistance to fluoroquinolones.

The eaeA gene is not found in Hafnia alvei from patients with diarrhea in Aragón, Spain

A total of 102 Hafnia alvei clinical strains isolated from different patients with diarrhea has been tested, using polymerase chain reaction and dot-blot hybridization, for the enteropathogenic Escherichia coli attaching and effacing A (eaeA) gene to establish their role as a causative agent of diarrhea in our environment. None of them was positive for the eaeA gene. We cannot consider the eaeA gene as the virulence-associated factor implicated in the H. alvei strains isolated from diarrheal feces in our region.

Distribution of resistance genes tet(M), aph3'-III, catpC194 and the integrase gene of Tn1545 in clinical Streptococcus pneumoniae harbouring erm(B) and mef(A) genes in Spain

The most prevalent macrolide resistance phenotype and genotype among pneumococcal isolates was the cMLSB phenotype [erm(B) or erm(B)/mef(A)] (91.3%). We studied the distribution of other resistance genes, tet(M), catpC194, aph3'-III, in these strains, seeing evolution at work in that some strains carried different combinations of resistance determinants. The most prevalent patterns associated with resistance to erythromycin [erm(B)] were resistance to tetracycline [tet(M)] and chloramphenicol (catpC194) (48.2%) or resistance to tetracycline [tet(M)] alone (42.2%). In our isolates of Streptococcus pneumoniae there was a strong association of the erm(B) and tet(M) genes with Tn1545-related elements.

[Association between MLS antibiotic and tetracycline resistance genes in Streptococcus pneumoniae]

In Streptococcus pneumoniae, resistance to macrolide, lincosamide and streptogramin type B (MLS(B)) antibiotics is mediated by erm(B) and mef(A) determinants. Tetracycline resistance is always associated with resistance to minocycline and is due to the presence of the tet(M) gene. The erm(B) determinant is predominant. We demonstrated that the erm(B) gene could be present with mef(A), which is of streptococcal origin, and msr(A), which is of staphylococcal origin, this being an example of genetic promiscuity. The tet(M) determinant was associated with pneumococci harboring the erm(B) gene, while it was not associated with the strains harboring the mef(A) gene. This association is due to the fact that, in most of the cases, erm(B) and tet(M) reside in the same chromosomal conjugative transposon.

Biochemical changes in needles of Pinus radiata D. Don trees in relationship to long-term ozone exposure indices

Ambient concentrations of ozone in Europe are high enough to cause negative effects on vegetation. Therefore, many efforts have been made to determine exposure indices and critical levels for protection of vegetation. In this context, the choice of a suitable attribute to determine the pollutant effect is of paramount importance. Until now, much of the work has been done with attributes such as biomass or growth. In the present work correlation factors have been established between biochemical parameters (peroxidase activity, ascorbate and sulfhydryl contents) of Pinus radiata trees and exposure indices of ozone. Our results show that peroxidase cannot be used as an indicator of effects of long-term exposure to ozone but still remains as an excellent indicator of short-term ozone fluctuations in the field. Ascorbate may act as an intermediate indicator responding to both short fluctuations and long-term exposures to ozone. Finally, sulfhydryl may be used as a long-term indicator in relation to the AOT (average over threshold) exposure index. Our results also point to the fact that Pinus radiata may be affected by ozone at AOT values lower than 10 ppm.h as already observed with other tree species.

[Presence of conjugative transposon Tn1545 in strains of Streptococcus pneumoniae with mef(A), erm(B), tet(M), catpC194 and aph3'-III genes]

We studied the association of MLS resistance genes (erm(B) and mef(A) with others non-MLS resistance genes: tet(M) (tetracycline and minocycline), catpC194 (chloramphenicol) and aph3'-III (kanamycin) in order to know how is selected the multiresistant in Streptococcus pneumoniae. The tet(M) and catpC194 genes were present very often in the pneumococci with the erm(B) gene but the aph3'-III was found only in four strains. Tn1545 was nearly always the responsible for the dissemination of these genes. In contrast, mef(A) was not associated with tet(M) and and catpC194 and is disseminated in a different conjugative transposon. The linkage of multiple antibiotic resistance genes on the same mobile element is of importance for public health, because the use of one antibiotic selects for the transposon which carries multidrug resistance genes.

Monitoring adenovirus infections with on-line and off-line methods

Several known process monitoring methods were tested for their efficacy in the detection of adenovirus infections. The methods that we explored include several indirect indications of viral infections, including metabolic rate analysis, secondary gauges of respiration, cell size measurement, cell number and cell viability determination, and changes in capacitance. Direct indications of the adenovirus infection were also applied, including total viral particle and infectious particle measurements, as well as a flow cytometry method for detecting infected cells. All of the methods tested in the study provide some positive indication of an adenovirus infection. Many of the methods require repeated sampling, which may limit their utility in a manufacturing process. All of the indirect measures of viral infection may be limited by the fact that they do not uniquely identify an infection. The simplest monitoring methods appear to be detection of changes in respiration or the capacitance of the culture, both of which seem to provide a clear indication of an infection. Further work will be required to demonstrate that these indications are characteristic of only a successful and productive adenovirus infection.

Astrovirus infection among children with gastroenteritis in the city of Zaragoza, Spain

The incidence of astrovirus infection in children less than 10 years of age with gastroenteritis in the city of Zaragoza, Spain, was analysed during a 12-month period. A total of 718 stool samples obtained from 534 children were examined. In 401 samples no routinely searched for pathogenic organism was detected; these specimens were then tested for the presence of astrovirus antigens. Astrovirus was detected in the samples of 15 (5.5%) patients, a detection rate similar to that recognised for Yersinia enterocolitica and Cryptosporidium spp. All children with confirmed astrovirus infection had diarrhoea (median duration, 9 days), 11 experienced loss of appetite, 5 vomiting, and 4 fever. The incidence of astrovirus infection reported here indicates that Spanish children suffering from gastroenteritis should be routinely screened for the presence of astrovirus.

Oxidative stress induced by copper in sunflower plants

The toxic effect of copper was evaluated in sunflower plants by means of root elongation, lipid peroxidation and antioxidative enzyme activities. Plants were grown under controlled environmental conditions in hydroponic culture for two weeks and exposed to different copper concentrations for an additional week. Determinations were performed in both roots and leaves. From the results of the root elongation test, a copper concentration of 10 microM was found to be toxic for sunflower plants causing lipid peroxidation and, thus, oxidative stress. Antioxidative enzymes (peroxidase and superoxide dismutase) responded at lower, nontoxic copper concentrations.

Antioxidative defense and photoprotection in Pinus halepensis induced by Mediterranean conditions and ozone exposure

Pigment levels and antioxidative stress-related metabolites were determined over a period of two years in Pinus halepensis to characterize the response of some plant protective processes to both environmental stresses and 03 exposure. Two-year-old-Aleppo pine seedlings were grown in open-top chambers under optimal nutrient and water conditions and exposed to different 03 levels: charcoal filtered air, non-filtered air and nonfiltered air plus 40 ppb O3 10 h/day. In summer an activation of photoprotective systems was observed since a decrease in chlorophyll levels, an increase in the carotenoid/chlorophyll ratio and SOD activation were recorded. Interestingly, the SOD activity in Pinus halepensis was highly related to low-molecular weight compounds and this relationship increased with needle age. Ozone exposure induced alterations in the activity of some antioxidant enzymes along with reductions in pigment concentrations and an activation of the xanthophyll cycle.

Visualization of hydatid elements: comparison of several techniques

Some techniques available at our laboratory were tested for their ability to aid in the morphological diagnosis of hydatid elements (Echinococcus granulosus ["Taenia echinococcus"]) isolated from cysts in humans and sheep. Unstained, methanol-fixed hooklets were fluorescent, most starkly so under violet light (excitation filter wavelength, 405 nm; long-pass filter wavelength, 495 nm). Auramine-rhodamine and Gram procedures failed to stain hooklets. Ziehl-Neelsen stain yielded indifferent results when organisms were viewed under transmitted light but resulted in a surprisingly intense red fluorescence when organisms were viewed under green light (excitation, 546 nm; long pass, 590 nm). Wheatley trichrome stain gave better and more uniform results than fuchsin. Ryan trichrome blue stain was the best under transmitted light; hooklets stained uniformly and intensely and were easily distinguishable from the background. Very satisfactory results were also obtained with a much simpler procedure (modified Baxby technique: no fixation, steaming hot 1% safranin for 2 min, and malachite green for 30 s). Therefore, Ryan and modified Baxby stains are recommended for the examination of E. granulosus under transmitted light. For fluorescence microscopy, Ziehl-Neelsen stain under green excitation light, or violet light with no staining, is also very useful. Epifluorescence microscopy is especially convenient for examining samples concentrated by filtration, as it renders the filter pores inconspicuous.

Hodgkin's disease: internal mammary lymph nodes relapse diagnosed by gallium-67 scintigraphy

This article presents the case of a 62-year-old man with treated Hodgkin's disease who had internal mammary lymph nodes relapse after a complete initial response. These masses were gallium avid. These findings were explained by histologically documented Hodgkin's relapse, the first such case reported in that localization without chest wall involvement. The literature on mediastinal Hodgkin's disease and diagnostic procedures are reviewed.

Fuchsin fluorescence and autofluorescence in Cryptosporidium, Isospora and Cyclospora oocysts

Cryptosporidium parvum and Isospora belli oocysts stained with carbol-fuchsin, as in a modified Ziehl Neelsen technique, fluoresce bright red under green light (546nm). Cryptosporidium oocysts tend to fluoresce more brightly the less intensely stained they appear under transmitted light; this is not the case with Isospora. Fuchsin-stained Cyclospora cayetanensis oocysts fluoresce rather dimly, but those not taking the dye retain their typical autofluorescence. Cryptosporidium and Isospora oocysts are also autofluorescent, appearing violet under u.v. light (365 nm), and green under violet (405 nm) and blue-violet light (436 nm). Their autofluorescence does not survive the staining procedure.

Use of a selective medium and a membrane filter method for isolation of Campylobacter species from Spanish paediatric patients

A study was conducted to assess the value of a combination of two culture methods for isolation of Campylobacter spp. from Spanish children. Seven hundred twenty-nine diarrhoeal stool specimens from 599 patients were examined for Campylobacter spp. by culturing them on charcoal cefoperazone deoxycholate agar and on blood agar with a membrane filter. One hundred sixteen Campylobacter strains were isolated from a total of 108 specimens; 75 (64.6%) were Campylobacter jejuni, 32 (27.5%) were Campylobacter coli, 8 (6.8%) were non-typeable, and one (0.9%) was Campylobacter upsaliensis. Campylobacters were isolated from 99 positive samples using charcoal cefoperazone deoxycholate agar alone. The filtration technique alone yielded only 86 positive samples. Seven specimens yielded different Campylobacter spp. with different media. The only catalase-negative strain was recovered using the filter method. The combination of the selective medium with the filter method increased the isolation rate of Campylobacter strains by 14.1%. Isolation rates of campylobacters using the filter method were similar to those reported in European studies, in which a similar frequency of Campylobacter upsaliensis was observed. The addition of a filter method for routine laboratory isolation of campylobacters should be considered in selected age groups (in children < 10 years of age) or in areas where catalase-negative or weakly-positive Campylobacter strains may be of epidemiological significance.

[Quinolone resistance in Salmonella enterica]

Nalidixic acid resistance is a marker of quinolone sensibility in Salmonella spp. In our laboratory we observed an increase of nalidixic acid resistant strains from 0.44% in 1990 to 13.7% in 1996. The purpose of this work was to study the evolution of nalidixic acid resistance in Salmonella spp., as well as the association with certain serotypes and the cross-resistance to others agents. A total of 1,782 isolates of Salmonella enterica were studied from fecal and blood sources over a 7-year period; 45 strains (2.52%) were resistant to nalidixic acid (MIC > 16 microgram/ml). Two isolates required 2 microgram/ml of ciprofloxacin for inhibition, while the remaining 43 strains required 1 microgram/ml. The most frequent serotypes in nalidixic acid resistant strains were the following: enteritidis (33.3%), hadar (31.11%) and virchow (15.5%). In 1996, enteritidis was the predominant serotype (13/31), and hadar serotype was found to have the greatest nalidixic acid resistance at 80% of strains. No differences of sensibility to other agents were detected between the nalidixic acid resistant group and nalidixic acid sensitive strains. This type of resistance appears regularly in uncommon serotypes such as hadar. The increasing incidence of resistant isolates in enteritidis in 1996 is of even greater concern.

Diplogonoporiasis presumably introduced into Spain: first confirmed case of human infection acquired outside the Far East

A 58-year-old man who was very fond of eating raw fish and had not left Zaragoza Province in Spain in the last 20 years excreted a short chain of gravid proglottids. Treatment with 50 mg/kg of paromomycin sulfate was divided into three doses, all given within the same day, followed by administration of a laxative at night. On days 1 and 2 post-treatment, several chains of degenerated proglottids were evacuated. Only eggs were expelled on days 3 and 4. A long complete strobila including the scolex, and immature, mature, and gravid segments was spontaneously discharged on day 25 after treatment. It was identified as Diplogonoporus balaenopterae, and was the first confirmed case of diplogonoporiasis outside the Far East (all previous cases were reported from Japan, except for one recent case reported from Korea). The origin of this case, outside of its normal geographic location, may be associated with the importation of fish into Spain. The viability of the infective larval stage is evidence of its resistance to export/import conditions. Treatment with paromomycin sulfate did not result in the whole worm being discharged but several short strobilar chains showed drug-induced degeneration.

[Antibiotic resistance in Salmonella enterica: an increasing problem]

OBJECTIVE

To determine the evolution of the frequencies of Salmonella enterica serotypes and their resistance to antimicrobial agents.

METHOD

A retrospective study of all S. enterica strains isolated from stool samples in the Hospital Clinico Universitario of Zaragoza over the period 1990-1994.

RESULTS

Enteritidis was the most frequently isolated serotype (62.9%), although it showed a progressive decrease (from 76.2% in 1990 to 39.8% in 1994). Typhimurium was the serotype showing the highest resistance levels, 37.1% of its isolates being resistant to ampicillin, streptomycin, chloramphenicol and tetracyclin. There was a distinct increase in the frequency of multiresistant strains, from 9.7% in 1990 to 22.9% in 1994. Of 88 such strains, 78.4% corresponded to serogroup B, whereas only 4.5% to serogroup D. Of the antimicrobial agents traditionally considered elective, only cotrimoxazole maintained acceptable resistance levels (4.4%). Resistance to fluoroquinolones or 3rd-generation cephalosporines was not detected.

CONCLUSIONS

The increasing frequency of Typhimurium, a highly resistant serotype, restrains the elective antimicrobial agents to cotrimoxazole in children and fluoroquinolones in adults. 3rd-generation cefalosporines may be a good alternative in case of therapeutic failure.

Respiratory cryptosporidiosis: case series and review of the literature

Five case of intestinal cryptosporidiosis with pulmonary involvement in patients with AIDS are reported. The diagnosis was based on the recognition of acid-fast oocysts in sputum or aspirated bronchial material and stool specimens. Coughing and excess secretions were present in all cases. Four patients had other associated pulmonary pathogens: two Mycobacterium tuberculosis, one Mycobacterium fortuitum and one Cytomegalovirus + Pneumocystis carinii; all of them had a previous (three cases) or simultaneous (one case) diagnosis of intestinal cryptosporidiosis, presenting with diarrhoea and vomiting. In the fifth patient Cryptosporidium was the only pulmonary pathogen found in a bronchial aspirate, and the onset of diarrhoea was 1 month after respiratory detection. Fifty-seven cases of respiratory cryptosporidiosis have been reported since 1980. In 17 of them, no other pathogen was found. Diarrhoea was present in 77% of the patients, cough in 77%, dyspnea in 58%, expectoration in 54%, fever in 45%, thoracic pain in 33%.

Comparison of 2 centrifugation procedures in the formalin-ethyl acetate stool concentration technique for the detection of Cryptosporidium oocysts

A comparison between the standard formalin-ethyl acetate (FEA) stool concentration procedure (centrifugation at 400 g for 2 min) and a modification proposed to increase the recovery of Cryptosporidium oocysts (500 g for 10 min) was performed on 73 formalin-preserved stool specimens known to be positive for Cryptosporidium. False-negative results were obtained with both methods, but the increase in centrifugation time and force resulted in the detection of a higher number of oocysts and positive samples. The modified procedure had a sensitivity significantly higher than the standard method (99% compared to 86%, P = 0.0045).

Evaluation of the optimal number of faecal specimens in the diagnosis of cryptosporidiosis in AIDS and immunocompetent patients

This study determines the optimal number of faecal samples that should be examined in order to minimize the occurrence of false-negative results in the diagnosis of cryptosporidiosis using routine techniques. A total of 23,023 faecal samples from 10,870 patients submitted for parasitological examination were processed by the formalin-ethyl acetate concentration technique and stained using a modified Ziehl-Neelsen method. Cryptosporidiosis was diagnosed in 232 patients (2.13%), 44 of whom were infected by HIV, the prevalence rate in this population group being 15.54%. The increase in the number of diagnoses obtained by the examination of n and (n-1) specimens was evaluated statistically. This study found that three is the optimal number of faecal samples that should be examined when cryptosporidiosis is suspected in immunocompetent patients; whereas, only two samples are required for diagnosing this protozoosis in AIDS patients.

[Phenotypic characterization and distribution of Yersinia in human and environmental samples]

The distribution of species and phenotypes of Yersinia isolated from environmental samples over an eight year period are compared to that of stool cultures obtained from patients of the same geographical location (Zaragoza, Spain). The number of samples and the percentage contamination were as follows: wastewater 362, 67.4%, freshwater 523, 13.4%, raw food 607, 24.5% and cooked food 1134, 7.9%. Yersinia enterocolitica was isolated significantly more frequently than other species in wastewater, while Yersinia intermedia was the most significant species found in freshwater. Significant differences between the percentage isolates of identified species in raw and cooked foods were not found. Fifteen different serogroups were identified from faeces, thirteen of which were also isolated from environmental samples. Three serogroups of Y. enterocolitica associated with human disease were isolated from the patients faeces as follows: O:3, 145 cases; O:8, 3 cases and O:5,27, 1 case. A low proportion were isolated from food: O:3, 3 strains; O:8, 2 strains and O:5,27, 5 strains. Only one isolate from serogroup O:3 was obtained from freshwater.

A reverse transcriptase-polymerase chain reaction assay for the detection and quantitation of murine retroviruses

Specific hybridization primers for the PCR assay were developed to detect the presence of the ecotropic, xenotropic, and mink cell focus-forming classes of murine leukemia viruses (MuLVs) in samples derived from cultured cells and cell-free supernatants. The primers, which were tested against reference viruses from all three classes and two subclasses and accurately identified each class present, were used to characterize the endogenous expression of MuLV-related sequences in a number of murine and mink cell lines. Two murine/murine hybridomas were shown to contain expressed retroviral sequences from all three classes. The murine cell lines SC-1, Balb/c 3T3, and NIH 3T3, were found to constitutively express sequences from many of the MuLV classes. These MuLV-related sequences were not expressed in the Mus dunni or mink lung cell lines. When these primers were used in a quantitative PCR assay to determine the retroviral content of hybridoma supernatants, the values were less variable than those obtained by transmission electron microscopy (TEM). This assay can be adapted to detect and quantitate any viral contaminant in cell culture supernatants, ascites fluids, process validation samples, and final products.

[Epidemiology of shigellosis and colicin typing of Shigella sonnei. A 14-year study]

To study the most important epidemiologic features of shigellosis and the application of colicinotyping as an epidemiologic marker for Shigella sonnei. A total of 44.818 stoll-cultures were performed. We classify, using colicinotyping, 156 Shigella sonnei strains isolated from different patients. The incidence of Shigellosis in our media is low (1.08% of all stool-cultures). It is more frequent in pediatric population and increases on late summer and fall. We had been able to show an increasing incidence, with an hyperendemic situation during a three-years period (1981-1983). Shigella sonnei is the most prevalent species (86% of cases), followed by S. boydii (7.3%) and S. flexneri (5.9%). All S. sonnei strains epidemiologically related showed the same colicinotype. Only two strains were not typable and we identified 9 different colicinotypes, being type 13 (30.8%), type 8 (18.6%), type 6 (17.3%) and type 12 (11.54%) the more frequent types. Colicinotype 8 was the more prevalent between 1978-1979. Type 13 was predominant between 1981 and 1985. During 1987 and 1989, at the same time that incidence had risen, types 6 and 12 were prevalent. The total number of different colicinotypes identified during a single year is never greater than five. Colicinotyping of S. sonnei is a simple typing method that gives enough useful epidemiologic information, discriminative and reproducible. Although there are changes of circulating types incidence and the prevalen colicinotype colud vary from one year to another, during longer periods of time there is a reduced number of alternating colicinotypes, which sets up a situation that could be further classified as endemic.

[Leukocyte migration inhibitory factor and basophil degranulation in drug reactions]

We performed a prospective study in patients with a medical history of adverse reaction to drugs with the purpose of rule out allergy. We included 31 patients who were attended in the Allergy Service. We compared the sensibility and specificity of the test of inhibition factor of leucocytes migration and degranulation basophil against the exposition. After the statistical analysis, we concluded: the laboratory test, we have already mentioned, have little sensibility and specificity so the exposition test in the quickest, useful, and more simple method to determine drugs allergy, but more dangerous.