Julio Vazquez - Academia.edu (original) (raw)

Papers by Julio Vazquez

Research paper thumbnail of Antibiotic resistance of Neisseria gonorrhoeae in Spain: trends over the last two decades

Journal of Antimicrobial Chemotherapy, 2003

In vitro activities of six antimicrobial agents against 2966 strains of Neisseria gonorrhoeae, is... more In vitro activities of six antimicrobial agents against 2966 strains of Neisseria gonorrhoeae, isolated in Spain between 1983 and 2001, were determined. The percentages of intermediately susceptible and resistant isolates to penicillin (MIC ≥ 0.12 mg/L) and tetracycline (MIC ≥ 0.5 mg/L) were very high over the period of study. Strains intermediately susceptible to cefoxitin were identified at a variable percentage during the study. All N. gonorrhoeae isolates were susceptible to spectinomycin and ceftriaxone. Recently, resistance to ciprofloxacin has emerged.

Research paper thumbnail of Interlaboratory comparison of agar dilution and etest methods for determining the MICs of antibiotics used in management of Neisseria meningitidis infections

Journal of Immunology, 2003

Previous studies have shown that there is considerable variation in the methods and media used to... more Previous studies have shown that there is considerable variation in the methods and media used to determine the susceptibility of Neisseria meningitidis to antimicrobial agents in different countries. In this study, national and regional reference laboratories used a standardized methodology to determine the MICs of antibiotics used in the management of meningococcal infection. Fourteen laboratories participated in the study, determining the susceptibility to penicillin G, rifampin, cefotaxime, ceftriaxone, ciprofloxacin, and ofloxacin of a collection of 17 meningococci, of which 11 strains were previously defined as having intermediate resistance to penicillin (Pen I ) by sequencing and restriction fragment length polymorphism analysis of the penA gene. The MIC was determined by agar dilution and Etest with Mueller-Hinton agar (MH), MH supplemented with sheep blood (MH؉B), and MH supplemented with heated (chocolated) blood. Several laboratories encountered problems obtaining confluent growth with unsupplemented MH. MH؉B was considered to give the most congruent and reproducible results among the study laboratories. The modal MIC for MH؉B for each antibiotic and method was calculated to define the MIC consensus, allowing assessment of each individual laboratory's data in relation to the others. The agreement in each antibiotic/method/medium combination was defined as the percentage of laboratories with a result within one dilution of the modal result. For the whole study, an agreement of 90.6% was observed between agar dilution and Etest methods. The agreement in each laboratory/antibiotic/method combination ranged from 98.2% to 69.7%, with six laboratories demonstrating agreement higher than 90% and 11 more than 80%. The ability of the laboratories to detect the Pen I isolates ranged from 18.2% to 100%. The apparent difficulty in interpreting susceptibility to rifampin, particularly with the Etest method, is very interesting.

Research paper thumbnail of Increasing Incidence of Meningococcal Disease in Spain Associated with a New Variant of Serogroup C

European Journal of Clinical Microbiology & Infectious Diseases, 1998

Serogroup B has been the main cause of meningococcal disease in Spain since at least 1979, but in... more Serogroup B has been the main cause of meningococcal disease in Spain since at least 1979, but in recent years an increase in the prevalence of infection due to serogroup C meningococci has been detected. In 1996, for the first time, most cases of meningococcal disease were caused by serogroup C strains. The sero/subtype of all serogroup C meningococci received from 1993 to June 1996 was determined, and the results showed that C:2b:P1.2,5, the most common phenotype in 1995 and 1996 (63% and 65%, respectively), represented only 4.8% of strains in !993. The C:2b:P1.2,5 epidemic strains appear to be responsible for the high prevalence of serogroup C in Spain. One hundred fifty-one randomly selected serogroup C strains were analyzed by multilocus enzyme electrophoresis, ribotyping, and pulsedfield gel electrophoresis. Pulsed-field gel electrophoresis provided the most accurate information: more than 80% of the C:2b:P1.2,5 and C:2b:P1.2 isolates exhibited one of two very closely related profiles, while most of the C: 2b: NST and C: 2b: P1.5 strains had a pattern located at a genetic distance of 0.24 from those two profiles. The results show that C:2b:P1.2,5 strains represent a subclone or a genetic variant of the previously identified Spanish epidemic clone C:2b:non-subtypable strains.

Research paper thumbnail of Carriage of a new epidemic strain of Neisseria meningitidis and its relationship with the incidence of meningococcal disease in Galicia, Spain

Epidemiology and Infection, 1999

In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in the ... more In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in the 1995-6. The annual incidence rose to 11 per 10& inhabitants, and 80 % of identified strains were C : 2b : P1.2,5. This led to the implementation of an intensive AjC vaccination campaign for the population aged 18 months to 19 years. During this campaign the prevalence of carriage in areas with high and low incidence was studied. Nasopharyngeal swabs were taken from 9796 subjects immediately before the administration of meningococcal vaccine, plated onto Thayer-Martin plates, incubated and sent for analysis to the Reference Laboratory for Neisseria in Spain. The prevalence of the C : 2b : P1.2,5 strains was 0n6 % (95 % CI 0n29-0n88) in the high incidence area, and 0n41 % (95 % CI 0n00-1n04) in the low incidence area, and that of serogroup C (all strains) 1n36 % (95 % CI 0n80-1n80) and 0n89 % (95 % CI 0n09-1n69) respectively. The prevalence of N. meningitidis (all strains) was almost the same in both areas (8 %). Carriers of the epidemic strain were not found in the 2-4 year age group, that most affected by the disease.

Research paper thumbnail of Development of a Multilocus Sequence Typing Method for Analysis of Listeria monocytogenes Clones

Journal of Clinical Microbiology, 2003

This study is a first step in the development of multilocus sequence typing (MLST) method for Lis... more This study is a first step in the development of multilocus sequence typing (MLST) method for Listeria monocytogenes. Nine housekeeping genes were analyzed in a set of 62 strains isolated from different sources and geographic locations in Spain. These strains were previously characterized by pulsed-field gel electrophoresis (PFGE). Because of low diversity, two loci were discarded from the study. The sequence analysis of the seven remaining genes showed 29 different allelic combinations, with 22 of them represented by only one strain. The results of this sequence analysis were generally consistent with those of PFGE. Because MLST allows the easy comparison and exchange of results obtained in different laboratories, the future application of this new molecular method could be a useful tool for the listeriosis surveillance systems that will allow the identification and distribution of analysis of L. monocytogenes clones in the environment.

Research paper thumbnail of The epidemic wave of meningococcal disease in Spain in 1996-1997: probably a consequence of strain displacement

During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studi... more During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studies described the antigenic expression of the epidemic strain as C:2b:P1.2,5 and proposed that it was a variant of the previously identified Spanish C:2b:nonsubtypable epidemic strain. To clarify this hypothesis, 1036 C:2b:P1.2(5) and 76 C:2b:NST isolates obtained during 1992-1999 were analysed by pulsed-field gel electrophoresis. The majority of the C:2b:P1.2,5 and C:2b:P1.2 isolates showed one of two very closely related profiles. During the epidemic period, 80% of the C:2b:NST strains showed these two pulsotypes. However, before the epidemic wave, most of these C:2b:NST strains (60%) showed a profile that was found infrequently among C:2b:P1.2,5 and C:2b:P1.2 isolates. A similar evolution was observed in C:2b:P1.5 isolates. Thirty-four C:2b:P1.2(5) and 10 C:2b:NST isolates, exhibiting representative pulsotypes, were subjected to multi-locus sequence typing. Isolates belonging to both A4 and ET-37 lineages were identified. These data point to the possibility that the A4 cluster has displaced the ET-37 complex among serogroup C meningococci in Spain.

Research paper thumbnail of Emergence of gonococcal strains with resistance to azithromycin in Spain

Journal of Antimicrobial Chemotherapy, 2003

Sir, Gonorrhoea and chlamydial infections are the most frequent sexually transmitted diseases glo... more Sir, Gonorrhoea and chlamydial infections are the most frequent sexually transmitted diseases globally. Over the past few years, several studies have been carried out to define the efficacy of azithromycin, a modified macrolide antibiotic, for treatment of both of these sexually transmitted diseases. These studies have shown that a single oral dose of azithromycin would ensure adequate therapy for both infections. Because Neisseria gonorrhoeae quickly develop resistance to antimicrobial agents, 2 it is necessary to have information on azithromycin susceptibility. Gonococcal strains showing decreased susceptibility to azithromycin have been described in several countries. The susceptibility of gonococcal strains to β-lactams (penicillin, cefoxitin and ceftriaxone), tetracycline, spectinomycin and fluoroquinolones (ciprofloxacin) is routinely tested in the Spanish Neisseria Reference Laboratory. Azithromycin susceptibility has not been studied.

Research paper thumbnail of Antibiotic Susceptibility Patterns of Neisseria meningitidis Isolates from Patients and Asymptomatic Carriers

Antimicrobial Agents and Chemotherapy, 2000

The activities of seven antimicrobial agents used for treatment and prophylaxis of meningococcal ... more The activities of seven antimicrobial agents used for treatment and prophylaxis of meningococcal disease was investigated against 901 Neisseria meningitidis isolates, 112 of which were recovered from patients and 789 of which were recovered from asymptomatic carriers. The proportions of isolates with decreased susceptibility to penicillin were 55.3 and 39.0%, respectively. Penicillin-and ampicillin-intermediate strains were more common among serogroup C meningococci than among non-serogroup C meningococci from both patients and carriers.

Research paper thumbnail of In Vitro Susceptibilities of 400 Spanish Isolates of Neisseria gonorrhoeae to Gemifloxacin and 11 Other Antimicrobial Agents

Antimicrobial Agents and Chemotherapy, 2000

The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 s... more The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 strains of Neisseria gonorrhoeae was determined by microdilution with supplemented GC agar. A total of 37.5% of the strains were ␤-lactamase positive. A total of 70 and 6.4% of the ␤-lactamase-negative strains exhibited intermediate and high-level penicillin resistance, respectively. Ceftriaxone and gemifloxacin were the most active drugs (MICs at which 90% of isolates are inhibited, 0.01 versus 0.007 g/ml, respectively), with 100% of strains inhibited by 0.12 g/ml.

Research paper thumbnail of Latex agglutination for bacterial antigens and meningococcus PCR: two useful tools in legal sudden deaths

Forensic Science International, 2005

Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infe... more Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infections caused by Neisseria meningitidis is an essential duty of medicolegal offices due to the risk of secondary cases. Since other microorganisms, such as Haemophilus influenzae and Streptococcus pneumoniae, are also involved in infectious sudden deaths, the identification of the pathogen responsible for death is essential in order to establish a positive diagnosis while also preventing secondary meningococcal cases. However, because of the unreliability of culture methods used for autopsy specimens and the fragile nature of the microorganisms, other techniques were used. In this study, the detection of specific antigens of N. meningitidis (serogroups A, B, C, Y and W135), H. influenzae type b, S. pneumoniae and Group B Streptococcus was undertaken in 40 samples from sudden death cases in legal procedures with a latex agglutination test. In addition, a meningococcus polymerase chain reaction (PCR) assay (ctrA, crgA and siaD genes) was also used as a corroboration method for positive N. meningitidis agglutinations.

Research paper thumbnail of Antibiotic resistance of Neisseria gonorrhoeae in Spain: trends over the last two decades

Journal of Antimicrobial Chemotherapy, 2003

In vitro activities of six antimicrobial agents against 2966 strains of Neisseria gonorrhoeae, is... more In vitro activities of six antimicrobial agents against 2966 strains of Neisseria gonorrhoeae, isolated in Spain between 1983 and 2001, were determined. The percentages of intermediately susceptible and resistant isolates to penicillin (MIC ≥ 0.12 mg/L) and tetracycline (MIC ≥ 0.5 mg/L) were very high over the period of study. Strains intermediately susceptible to cefoxitin were identified at a variable percentage during the study. All N. gonorrhoeae isolates were susceptible to spectinomycin and ceftriaxone. Recently, resistance to ciprofloxacin has emerged.

Research paper thumbnail of Interlaboratory comparison of agar dilution and etest methods for determining the MICs of antibiotics used in management of Neisseria meningitidis infections

Journal of Immunology, 2003

Previous studies have shown that there is considerable variation in the methods and media used to... more Previous studies have shown that there is considerable variation in the methods and media used to determine the susceptibility of Neisseria meningitidis to antimicrobial agents in different countries. In this study, national and regional reference laboratories used a standardized methodology to determine the MICs of antibiotics used in the management of meningococcal infection. Fourteen laboratories participated in the study, determining the susceptibility to penicillin G, rifampin, cefotaxime, ceftriaxone, ciprofloxacin, and ofloxacin of a collection of 17 meningococci, of which 11 strains were previously defined as having intermediate resistance to penicillin (Pen I ) by sequencing and restriction fragment length polymorphism analysis of the penA gene. The MIC was determined by agar dilution and Etest with Mueller-Hinton agar (MH), MH supplemented with sheep blood (MH؉B), and MH supplemented with heated (chocolated) blood. Several laboratories encountered problems obtaining confluent growth with unsupplemented MH. MH؉B was considered to give the most congruent and reproducible results among the study laboratories. The modal MIC for MH؉B for each antibiotic and method was calculated to define the MIC consensus, allowing assessment of each individual laboratory's data in relation to the others. The agreement in each antibiotic/method/medium combination was defined as the percentage of laboratories with a result within one dilution of the modal result. For the whole study, an agreement of 90.6% was observed between agar dilution and Etest methods. The agreement in each laboratory/antibiotic/method combination ranged from 98.2% to 69.7%, with six laboratories demonstrating agreement higher than 90% and 11 more than 80%. The ability of the laboratories to detect the Pen I isolates ranged from 18.2% to 100%. The apparent difficulty in interpreting susceptibility to rifampin, particularly with the Etest method, is very interesting.

Research paper thumbnail of Increasing Incidence of Meningococcal Disease in Spain Associated with a New Variant of Serogroup C

European Journal of Clinical Microbiology & Infectious Diseases, 1998

Serogroup B has been the main cause of meningococcal disease in Spain since at least 1979, but in... more Serogroup B has been the main cause of meningococcal disease in Spain since at least 1979, but in recent years an increase in the prevalence of infection due to serogroup C meningococci has been detected. In 1996, for the first time, most cases of meningococcal disease were caused by serogroup C strains. The sero/subtype of all serogroup C meningococci received from 1993 to June 1996 was determined, and the results showed that C:2b:P1.2,5, the most common phenotype in 1995 and 1996 (63% and 65%, respectively), represented only 4.8% of strains in !993. The C:2b:P1.2,5 epidemic strains appear to be responsible for the high prevalence of serogroup C in Spain. One hundred fifty-one randomly selected serogroup C strains were analyzed by multilocus enzyme electrophoresis, ribotyping, and pulsedfield gel electrophoresis. Pulsed-field gel electrophoresis provided the most accurate information: more than 80% of the C:2b:P1.2,5 and C:2b:P1.2 isolates exhibited one of two very closely related profiles, while most of the C: 2b: NST and C: 2b: P1.5 strains had a pattern located at a genetic distance of 0.24 from those two profiles. The results show that C:2b:P1.2,5 strains represent a subclone or a genetic variant of the previously identified Spanish epidemic clone C:2b:non-subtypable strains.

Research paper thumbnail of Carriage of a new epidemic strain of Neisseria meningitidis and its relationship with the incidence of meningococcal disease in Galicia, Spain

Epidemiology and Infection, 1999

In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in the ... more In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in the 1995-6. The annual incidence rose to 11 per 10& inhabitants, and 80 % of identified strains were C : 2b : P1.2,5. This led to the implementation of an intensive AjC vaccination campaign for the population aged 18 months to 19 years. During this campaign the prevalence of carriage in areas with high and low incidence was studied. Nasopharyngeal swabs were taken from 9796 subjects immediately before the administration of meningococcal vaccine, plated onto Thayer-Martin plates, incubated and sent for analysis to the Reference Laboratory for Neisseria in Spain. The prevalence of the C : 2b : P1.2,5 strains was 0n6 % (95 % CI 0n29-0n88) in the high incidence area, and 0n41 % (95 % CI 0n00-1n04) in the low incidence area, and that of serogroup C (all strains) 1n36 % (95 % CI 0n80-1n80) and 0n89 % (95 % CI 0n09-1n69) respectively. The prevalence of N. meningitidis (all strains) was almost the same in both areas (8 %). Carriers of the epidemic strain were not found in the 2-4 year age group, that most affected by the disease.

Research paper thumbnail of Development of a Multilocus Sequence Typing Method for Analysis of Listeria monocytogenes Clones

Journal of Clinical Microbiology, 2003

This study is a first step in the development of multilocus sequence typing (MLST) method for Lis... more This study is a first step in the development of multilocus sequence typing (MLST) method for Listeria monocytogenes. Nine housekeeping genes were analyzed in a set of 62 strains isolated from different sources and geographic locations in Spain. These strains were previously characterized by pulsed-field gel electrophoresis (PFGE). Because of low diversity, two loci were discarded from the study. The sequence analysis of the seven remaining genes showed 29 different allelic combinations, with 22 of them represented by only one strain. The results of this sequence analysis were generally consistent with those of PFGE. Because MLST allows the easy comparison and exchange of results obtained in different laboratories, the future application of this new molecular method could be a useful tool for the listeriosis surveillance systems that will allow the identification and distribution of analysis of L. monocytogenes clones in the environment.

Research paper thumbnail of The epidemic wave of meningococcal disease in Spain in 1996-1997: probably a consequence of strain displacement

During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studi... more During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studies described the antigenic expression of the epidemic strain as C:2b:P1.2,5 and proposed that it was a variant of the previously identified Spanish C:2b:nonsubtypable epidemic strain. To clarify this hypothesis, 1036 C:2b:P1.2(5) and 76 C:2b:NST isolates obtained during 1992-1999 were analysed by pulsed-field gel electrophoresis. The majority of the C:2b:P1.2,5 and C:2b:P1.2 isolates showed one of two very closely related profiles. During the epidemic period, 80% of the C:2b:NST strains showed these two pulsotypes. However, before the epidemic wave, most of these C:2b:NST strains (60%) showed a profile that was found infrequently among C:2b:P1.2,5 and C:2b:P1.2 isolates. A similar evolution was observed in C:2b:P1.5 isolates. Thirty-four C:2b:P1.2(5) and 10 C:2b:NST isolates, exhibiting representative pulsotypes, were subjected to multi-locus sequence typing. Isolates belonging to both A4 and ET-37 lineages were identified. These data point to the possibility that the A4 cluster has displaced the ET-37 complex among serogroup C meningococci in Spain.

Research paper thumbnail of Emergence of gonococcal strains with resistance to azithromycin in Spain

Journal of Antimicrobial Chemotherapy, 2003

Sir, Gonorrhoea and chlamydial infections are the most frequent sexually transmitted diseases glo... more Sir, Gonorrhoea and chlamydial infections are the most frequent sexually transmitted diseases globally. Over the past few years, several studies have been carried out to define the efficacy of azithromycin, a modified macrolide antibiotic, for treatment of both of these sexually transmitted diseases. These studies have shown that a single oral dose of azithromycin would ensure adequate therapy for both infections. Because Neisseria gonorrhoeae quickly develop resistance to antimicrobial agents, 2 it is necessary to have information on azithromycin susceptibility. Gonococcal strains showing decreased susceptibility to azithromycin have been described in several countries. The susceptibility of gonococcal strains to β-lactams (penicillin, cefoxitin and ceftriaxone), tetracycline, spectinomycin and fluoroquinolones (ciprofloxacin) is routinely tested in the Spanish Neisseria Reference Laboratory. Azithromycin susceptibility has not been studied.

Research paper thumbnail of Antibiotic Susceptibility Patterns of Neisseria meningitidis Isolates from Patients and Asymptomatic Carriers

Antimicrobial Agents and Chemotherapy, 2000

The activities of seven antimicrobial agents used for treatment and prophylaxis of meningococcal ... more The activities of seven antimicrobial agents used for treatment and prophylaxis of meningococcal disease was investigated against 901 Neisseria meningitidis isolates, 112 of which were recovered from patients and 789 of which were recovered from asymptomatic carriers. The proportions of isolates with decreased susceptibility to penicillin were 55.3 and 39.0%, respectively. Penicillin-and ampicillin-intermediate strains were more common among serogroup C meningococci than among non-serogroup C meningococci from both patients and carriers.

Research paper thumbnail of In Vitro Susceptibilities of 400 Spanish Isolates of Neisseria gonorrhoeae to Gemifloxacin and 11 Other Antimicrobial Agents

Antimicrobial Agents and Chemotherapy, 2000

The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 s... more The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 strains of Neisseria gonorrhoeae was determined by microdilution with supplemented GC agar. A total of 37.5% of the strains were ␤-lactamase positive. A total of 70 and 6.4% of the ␤-lactamase-negative strains exhibited intermediate and high-level penicillin resistance, respectively. Ceftriaxone and gemifloxacin were the most active drugs (MICs at which 90% of isolates are inhibited, 0.01 versus 0.007 g/ml, respectively), with 100% of strains inhibited by 0.12 g/ml.

Research paper thumbnail of Latex agglutination for bacterial antigens and meningococcus PCR: two useful tools in legal sudden deaths

Forensic Science International, 2005

Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infe... more Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infections caused by Neisseria meningitidis is an essential duty of medicolegal offices due to the risk of secondary cases. Since other microorganisms, such as Haemophilus influenzae and Streptococcus pneumoniae, are also involved in infectious sudden deaths, the identification of the pathogen responsible for death is essential in order to establish a positive diagnosis while also preventing secondary meningococcal cases. However, because of the unreliability of culture methods used for autopsy specimens and the fragile nature of the microorganisms, other techniques were used. In this study, the detection of specific antigens of N. meningitidis (serogroups A, B, C, Y and W135), H. influenzae type b, S. pneumoniae and Group B Streptococcus was undertaken in 40 samples from sudden death cases in legal procedures with a latex agglutination test. In addition, a meningococcus polymerase chain reaction (PCR) assay (ctrA, crgA and siaD genes) was also used as a corroboration method for positive N. meningitidis agglutinations.