Latin American Medical Centers Research Articles

Landscape of Invasive Fusariosis in Pediatric Cancer Patients: Results of a Multicenter Observational Study From Latin America.

Invasive fusariosis (IF) is a life-threatening opportunistic infection that affects vulnerable hosts. We conducted a multicenter and multinational retrospective study to characterize the natural history and clinical management of IF in pediatric cancer patients. We selected patients <18 years old who were sequentially hospitalized in 10 Latin American medical centers with a diagnosis of IF between 2002 and 2021. Data were collected using an electronic case report form complemented by a dictionary of terms. We assessed mortality rates at 30, 60, and 90 days. We collected data from 60 episodes of IF (median age, 9.8 years) that were mostly documented in patients with hematologic cancer (70%). Other risk conditions found were lymphopenia (80%), neutropenia (76.7%), and corticosteroid exposure (63.3%). IF was disseminated in 55.6% of patients. Skin lesions was present in 58.3% of our patients, followed by pulmonary involvement in 55%, sinusitis in 21.7%, bone/joint involvement in 6.7% and 1 case each of endocarditis and brain abscess. Positive blood and skin biopsy cultures were detected in 60% and 48.3% of cases, respectively. Fusarium solani complex was the most commonly identified agent (66.6%). The majority of patients received monotherapy within the first 72 hours (71.6%), either with voriconazole or amphotericin B formulation. The mortality rates at 30, 60, and 90 days were 35%, 41.6%, and 45%, respectively. An important factor affecting mortality rates appears to be disseminated disease. The high percentage of patients with fungal involvement in multiple organs and systems highlights the need for extensive workup for additional sites of infection in severely immunocompromised children.

Emergence of cryptic species and clades of Meyerozyma guilliermondii species complex exhibiting limited in vitro susceptibility to antifungals in patients with candidemia.

Members of the Meyerozyma guilliermondii species complex are able to cause superficial and life-threatening systemic infections with low susceptibility to azoles and echinocandins. We tested 130 bloodstream M. guilliermondii complex isolates collected from eight Latin American medical centers over 18 years (period 1 = 2000-2008 and period 2 = 2009-2018) to investigate trends in species distribution and antifungal resistance. The isolates were identified by rDNA ITS region sequencing, and antifungal susceptibility tests were performed against fluconazole, voriconazole, anidulafungin, and amphotericin B using the CLSI microbroth method. M. guilliermondii sensu stricto (s.s.; n = 116) was the most prevalent species, followed by Meyerozyma caribbica (n = 12) and Meyerozyma carpophila (n = 2). Based on rDNA ITS identification, three clades within M. guilliermondii sensu stricto were characterized (clade 1 n = 94; clade 2 n = 19; and clade 3 n = 3). In the second period of study, we found a substantial increment in the isolation of M. caribbica (3.4% versus 13.8%; P = 0.06) and clade 2 M. guilliermondii s.s. exhibiting lower susceptibility to one or more triazoles. IMPORTANCE Yeast-invasive infections play a relevant role in human health, and there is a concern with the emergence of non-Candida pathogens causing disease worldwide. There is a lack of studies addressing the prevalence and antifungal susceptibility of different species within the M. guilliermondii complex that cause invasive infections. We evaluated 130 episodes of M. guilliermondii species complex candidemia documented in eight medical centers over 18 years. We detected the emergence of less common species within the Meyerozyma complex causing candidemia and described a new clade of M. guilliermondii with limited susceptibility to triazoles. These results support the relevance of continued global surveillance efforts to early detect, characterize, and report emergent fungal pathogens exhibiting limited susceptibility to antifungals.

Tedizolid in vitro activity against Gram-positive clinical isolates causing bone and joint infections in hospitals in the USA, Europe, Latin America, and the Asia-Pacific region (2015-2019)

As bone and joint infections (BJIs) frequently require prolonged, systemic antibiotic use, tedizolid is an attractive candidate for BJI therapy in adults and children. Tedizolid activity was evaluated against 1,193 Gram-positive isolates causing BJI in American (USA), European (EUR), Latin American (LATAM), and Asian-Pacific (APAC) medical centers. Isolates consecutively collected from 2015 to 2019 were susceptibility tested by CLSI broth microdilution. Staphylococcus aureus (69.2%) was the most common pathogen with a 25.9% MRSA rate and tedizolid MIC50/90 of 0.12/0.25 mg/L (100% susceptible). Tedizolid exhibited MIC50/90 values of 0.12/0.12 mg/L (98.9% susceptible) for CoNS (7.5% of BJI), 0.12/0.25 mg/L for streptococci, and 0.25/0.25 mg/L for enterococci. Overall, high susceptibility rates (100.0%) for linezolid, daptomycin, and vancomycin were observed. In summary, tedizolid had potent in vitro activity against contemporary Gram-positive cocci causing BJI in adults and children in USA, EUR, LATAM, and APAC hospitals.

Revisiting Species Distribution and Antifungal Susceptibility of Candida Bloodstream Isolates from Latin American Medical Centers.

The epidemiology of candidemia varies geographically, and there is still scarce data on the epidemiology of candidemia in Latin America (LA). After extensive revision of medical literature, we found reliable and robust information on the microbiological aspects of candidemia in patients from 11 out of 21 medical centers from LA countries and 1 out of 20 from Caribbean countries/territories. Based on 40 papers attending our search strategy, we noted that C. albicans remains the most common species causing candidemia in our region, followed by C. parapsilosis and C. tropicalis. In Argentina, Brazil, and Colombia, a trend towards an increase in frequency of C. glabrata candidemia was observed. Although resistance rates to fluconazole is under 3%, there was a slight increase in the resistance rates to C. albicans, C. parapsilosis and C. tropicalis isolates. Echinocandin resistance has been reported in a few surveys, but no single study confirmed the resistant phenotype reported by using molecular methods. We highlight the importance of conducting continuous surveillance studies to identify new trends in terms of species distribution of Candida and antifungal resistance related to episodes of candidemia in LA. This information is critical for helping clinicians to prevent and control Candida bloodstream infections in their medical centers.

Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014.

Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America.

Ceftaroline activity tested against contemporary Latin American bacterial pathogens (2011)

A total of 2484 target bacterial pathogens were collected (one per patient episode) from patients in 16 Latin American medical centers located in seven nations during 2011. Isolate identity was confirmed at a coordinating laboratory and susceptibility testing was performed for ceftaroline and comparator agents according to reference broth microdilution methods. A total of 30.0% of isolates were from respiratory tract, 29.4% from skin and skin structure, 21.4% from blood stream, 7.9% from urinary tract and 11.3% from other sites. Ceftaroline was active against Staphylococcus aureus (42.8% MRSA) with 83.6% of the isolates at ≤1mg/L and all isolates at ≤2mg/L (MIC5090, 0.25/2mg/L). National MRSA rates ranged from a low of 28.8% in Colombia to a high of 68.1% in Chile. All Streptococcus pyogenes and Streptococcus agalactiae were susceptible to ceftaroline (MIC50/90 values were at ≤0.015/≤0.015mg/L for both). All Streptococcus pneumoniae were susceptible to ceftaroline, linezolid, tigecycline and vancomycin. Susceptibility to ceftriaxone was at 88.4% (CLSI non-meningitis interpretive criteria) and 73.9% (CLSI meningitis interpretive criteria) for all S. pneumoniae. Ceftriaxone susceptibility was only at 33.3% (CLSI non-meningitis interpretive criteria) and 0.0% (CLSI meningitis interpretive criteria) for penicillin-intermediate (penicillin MIC, 4mg/L) strains. All Haemophilus influenzae (29.4% β-lactamase-positive) isolates were susceptible to ceftaroline, amoxicillin–clavulanate, ceftriaxone, and levofloxacin. For the Latin American region, the ESBL-phenotype rate was 37.6% for Escherichia coli and 53.3% for Klebsiella pneumoniae. Ceftaroline was not active against ESBL-phenotype strains but was active against >90.0% of the non-ESBL-phenotype. The spectrum of activity of ceftaroline against pathogens from Latin America indicates that it merits further study for its potential use in the Latin American region.

Antimicrobial resistance among Gram-negative bacilli isolated from Latin America: results from SENTRY Antimicrobial Surveillance Program (Latin America, 2008–2010)

This study updates the frequency and resistance rates of Gram-negative bacilli isolated from Latin American medical centers enrolled in the SENTRY Antimicrobial Surveillance Program. A total of 12,811 bacterial organisms, including 5704 Gram-negative bacilli (44.5%), were consecutively collected (1 per patient) between January 2008 and December 2010 from 10 Latin American medical centers located in Argentina, Brazil, Chile, and Mexico. Antimicrobial susceptibility testing was performed and interpreted by the Clinical and Laboratory Standards Institute broth microdilution method at a central laboratory. All Gram-negative organisms with reduced susceptibility to imipenem or meropenem (MIC, ≥ 2 μg/mL) were screened for carbapenemase production by the modified Hodge test and by polymerase chain reaction. ESBL rates were 18.1%, 12.8%, 23.8%, and 48.4% among Escherichia coli and 60.4%, 49.9%, 59.2%, and 33.3% among Klebsiella spp. from Argentina, Brazil, Chile, and Mexico, respectively. Meropenem-nonsusceptible Klebsiella spp. rate was highest in Brazil (11.1%), followed by Argentina (8.2%), Chile (5.0%), and Mexico (0.8%). Klebsiella pneumoniae carbapenemase (KPC)–producing K. pneumoniae was not detected in 2008, but emerged in 2009 (10 strains) and increased significantly in 2010 (44; P < 0.0001). blaKPC-2 was detected in 54 (65.9%) of 85 carbapenem-nonsusceptible K. pneumoniae. Meropenem-nonsusceptible P. aeruginosa was observed in 53.8%, 46.7%, 33.3%, and 28.8% of strains from Argentina, Brazil, Chile, and Mexico, respectively. Imipenem-resistant Acinetobacter spp. rates increased from 6.4%, 12.6%, and 0.0% in the 1997–1999 period to 84.9%, 71.4%, and 50.0% in 2008–2010 in Argentina, Brazil, and Chile, respectively. Oxacillinase (OXA)-producing Acinetobacter spp. was documented in Argentina (OXA-23 and -24), Brazil (OXA-23), Chile (OXA-58), and Mexico (OXA-24). Only colistin showed >77% overall coverage against the 5 most frequently isolated Gram-negative bacilli from Latin American Medical centers participating in the SENTRY Program.

Increased resistance to first-line agents among bacterial pathogens isolated from urinary tract infections in Latin America: time for local guidelines?

Emerging resistance phenotypes and antimicrobial resistance rates among pathogens recovered from community-acquired urinary tract infections (CA-UTI) is an increasing problem in specific regions, limiting therapeutic options. As part of the SENTRY Antimicrobial Surveillance Program, a total of 611 isolates were collected in 2003 from patients with CA-UTI presenting at Latin American medical centers. Each strain was tested in a central laboratory using Clinical Laboratory Standard Institute (CLSI) broth microdilution methods with appropriate controls. Escherichia coli was the leading pathogen (66%), followed by Klebsiella spp. (7%), Proteus mirabilis (6.4%), Enterococcus spp. (5.6%), and Pseudomonas aeruginosa (4.6%). Surprisingly high resistance rates were recorded for E. coli against first-line orally administered agents for CA-UTI, such as ampicillin (53.6%), TMP/SMX (40.4%), ciprofloxacin (21.6%), and gatifloxacin (17.1%). Decreased susceptibility rates to TMP/SMX and ciprofloxacin were also documented for Klebsiella spp. (79.1 and 81.4%, respectively), and P. mirabilis (71.8 and 84.6%, respectively). For Enterococcus spp., susceptibility rates to ampicillin, chloramphenicol, ciprofloxacin, and vancomycin were 88.2, 85.3, 55.9, and 97.1%, respectively. High-level resistance to gentamicin was detected in 24% of Enterococcus spp. Bacteria isolated from patients with CA-UTI in Latin America showed limited susceptibility to orally administered antimicrobials, especially for TMP/SMX and fluoroquinolones. Our results highlight the need for developing specific CA-UTI guidelines in geographic regions where elevated resistance to new and old compounds may influence prescribing decisions.

Analysis of Salmonella spp. with resistance to extended-spectrum cephalosporins and fluoroquinolones isolated in North America and Latin America: report from the SENTRY Antimicrobial Surveillance Program (1997–2004)

Emerging antimicrobial-resistant Salmonella spp. requires increased efforts to appropriately test susceptibility. The SENTRY Antimicrobial Surveillance Program monitored Salmonella spp. and detected nalidixic acid-resistant strains with elevated fluoroquinolone minimum inhibitory concentration (MIC) results and strains with extended-spectrum β-lactamase (ESBL) “phenotypes” over the last 8 years. A total of 786 stool and bloodstream isolates from North American and Latin American medical centers (2001–2003) were tested by reference broth microdilution methods. Genetic analysis was used to further characterize the resistance mechanisms. Twenty-one sites forwarded 89 (11.3%) nalidixic acid-resistant (MIC, ≥32 μg/mL) strains. Nineteen of these isolates were studied to determine mutations in the quinolone resistance-determining region (QRDR). Among the nalidixic acid-resistant Salmonella spp. isolates, fluoroquinolone MIC values were also elevated (8- to 32-fold) compared with “wild-type” strains. Ciprofloxacin and gatifloxacin (MIC 90, 0.5 μg/mL) were more potent than levofloxacin and garenoxacin (1 μg/mL) against nalidixic acid-resistant strains. Single gyrA mutations were responsible for elevated fluoroquinolone MIC values and included D87Y (5), S83F (7), D87N (5), and S83Y (2). During 2001, 9 sites contributed 11 (2.9%) strains that met ESBL screening criteria (≥2 μg/mL) for aztreonam or ceftazidime or ceftriaxone. ESBL confirmation was evaluated by Etest (AB BIODISK, Solna, Sweden) ESBL strips and the enzymes were characterized by polymerase chain reaction and gene sequencing. The ESBL phenotype isolates had the following MIC patterns: ceftazidime (≥16 μg/mL), aztreonam (4 to >16 μg/mL), and ceftriaxone (8–32 μg/mL). All strains were susceptible to cefepime, carbapenems, gentamicin, and fluoroquinolones. No strains were inhibited by clavulanic acid consistent with all isolates producing the identified CMY-2, AmpC-like enzyme. Fluoroquinolones may be compromised among isolates with QRDR mutations detected using nalidixic acid as a screening agent. Salmonella spp. with ESBL phenotypes were likely to harbor CMY-2 (not an ESBL) and remain susceptible to cefepime, carbapenems, and fluoroquinolones, which can be used for serious invasive Salmonella spp. infections. Compared with the stool culture isolates, the blood culture isolates had higher QRDR mutations, but remained susceptible to the fluoroquinolones. The blood culture isolates were more susceptible to penicillins (ampicillin and ticarcillin) and not significantly different for ceftriaxone or trimethoprim/sulfamethoxazole susceptibility patterns. No QRDR trends over time were detected in North America, but increased resistance was observed in Latin America.

Daptomycin In Vitro Activity Tested Against Gram-Positive Strains Collected from European and Latin American Medical Centers in 2003

Daptomycin, a cyclic lipopeptide, was susceptibility tested against clinical bacterial isolates consecutively collected in hospitals located in Europe (4,731 strains) and Latin America (1,007 strains) in 2003 as part of a continuing surveillance program. The bacterial isolates tested were Gram-positive pathogens that included staphylococci, streptococci and enterococci. The isolates were tested for susceptibility using broth microdilution methods (broth with 50 mg/L Ca++ for testing daptomycin). All isolates, except two Enterococcus faecium strains from Europe, were inhibited at daptomycin MIC of ≤4 mg/L. In addition, 99.4 and 97.3% of isolates were inhibited at daptomycin MIC of ≤2 and ≤1 mg/L, respectively. Except for one Staphylococcus aureus and one viridans group streptococci from Europe and one coagulase-negative staphylococci from Latin America, all staphylococcal and streptococcal isolates were inhibited by 1 mg/L of daptomycin. Resistance to other compounds (vancomycin, oxacillin, and penicillin) did not influence daptomycin activity. The activity of daptomycin was very similar in both geographic regions evaluated and demonstrated the same MIC distribution as isolates evaluated in studies in the United States. The results of this study showed that daptomycin continues to be very active against clinical isolates of Gram-positive cocci isolated in Europe and Latin America.

Genotypic Characterization of Carbapenem-NonsusceptibleAcinetobacterspp. Isolated in Latin America

The principal aim of this study was to evaluate the genomic diversity among the imipenem-nonsusceptible Acinetobacter spp. (INSA) collected from the Latin American medical centers within the SENTRY Antimicrobial Surveillance Program. The INSA isolates were collected from patients with bloodstream infections, who were hospitalized in seven Latin American countries between 1997 and 1999. For epidemiologic comparison, 20 carbapenem-susceptible Acinetobacter spp. (CSA) isolates were collected in the same period of time from the respective medical centers. A total of 23 Acinetobacter spp. isolates exhibiting imipenem MIC values of >/=8 microg/ml were typed by ribotyping, an automated molecular method. The isolates showing an identical ribogroup were also typed by pulsed-field gel electrophoresis (PFGE). The antimicrobial susceptibility to various antimicrobial agents was evaluated using a reference broth microdilution technique. Among the INSA isolates, 13 distinct ribogroups were observed, whereas 16 ribogroups were detected among the CSA. Nearly 57% of the INSA belonged to only four ribogroups. Identical ribogroups and PFGE patterns were observed among INSA and CSA isolates collected from medical centers located in different countries (Brazil and Argentina). Our results showed: (1) a higher genomic variability among the CSA; (2) presence of epidemic clones among INSA isolates encountered in Latin American medical centers; and (3) spread of INSA and CSA epidemic clones between Latin American countries.

Activity of Mupirocin and 14 Additional Antibiotics against Staphylococci Isolated from Latin American Hospitals: Report from the SENTRY Antimicrobial Surveillance Program

A total of 1,346 Staphylococcus aureus (SA) and 498 coagulase-negative staphylococcal (CoNS) strains isolated from 11 Latin American medical centers between 2000 and 2001 were tested against mupirocin and other antimicrobial agents by reference broth microdilution method as part of the SENTRY Antimicrobial Surveillance Program. Oxacillin resistance (OR) was detected in 38.6% of S. aureus and in 78.1% of CoNS. The overall resistance rate to mupirocin was low among S. aureus (3.1%; MIC ≥8 μd/ml) but significantly higher among ORSA compared to oxacillin-susceptible SA (5.4% versus 1.7%; p <0.001). Mupirocin-resistant S. aureus, strains were detected in 9 of 11 centers, with individual center rates varying between 1.8 and 15.7%. Mupirocin resistance rates were high among CoNS (27.5%) and varied widely (10.0 to 48.9%) among the monitored Latin American medical centers. Mupirocin resistance rates appear to be increasing and routine monitoring for potential resistance seems prudent.

Resistance trends of Acinetobacter spp. in Latin America and characterization of international dissemination of multi-drug resistant strains: five-year report of the SENTRY Antimicrobial Surveillance Program

Objectives: To analyze the antimicrobial susceptibility of Acinetobacter spp. isolates collected from Latin American medical centers as part of the SENTRY Antimicrobial Surveillance Program and also to evaluate the dissemination of multi-drug resistant Acinetobacter spp. strains in the region. Methods: A total of 826 isolates of Acinetobacter spp. from multiple infection sites were collected from January 1997 to December 2001 in ten medical centers and susceptibility tested to >25 selected agents by broth microdilution. Multi-drug resistant Acinetobacter spp. isolates were molecular typed. Results: Resistance rates to carbapenems varied significantly among countries. A continued annual increase occurred in the Argentinean medical centers. In contrast, carbapenem resistance was rare in Chilean centers, and decreased significantly in the Brazilian institutions. Acinetobacter spp. isolates recovered from lower respiratory tract and bloodstream infections were associated with lower antimicrobial susceptibility rates. Resistance rates to imipenem were higher among isolates collected from intensive care units (13.5%) than among isolates from other units. A major ribogroup pattern (521-1) was detected among eight Acinetobacter spp. strains isolated from three distinct Latin American countries. Conclusions: This study found that antimicrobial resistance is still a major issue among Acinetobacter spp. isolates collected from some Latin American countries. The dissemination of a major bacterial cluster in different regions reinforces the importance of longitudinal surveillance programs, such as SENTRY, as valuable tools for monitoring antimicrobial susceptibility rates and guiding local interventions.

Typing and molecular characterization of Streptococcus pneumoniae with reduced susceptibility to cefotaxime isolated in Latin America.

The treatment of systemic infections, especially meningitis, caused by Streptococcus pneumoniae nonsusceptible to third-generation cephalosporins, is extremely difficult due to the paucity of therapeutic options. The main objective of this study was to characterize isolates of S. pneumoniae with reduced susceptibility to cefotaxime (MICs, > or = 1 microg/ml) by different typing methods and to evaluate whether clonal dissemination of this pathogen had occurred among Latin American medical centers. A total of 46 isolates collected from respiratory tract specimens, blood cultures, cerebrospinal fluid, eye, and other sources were analyzed. The isolates were collected from Latin American medical centers located in Argentina, Brazil, Chile, Colombia, Mexico, and Uruguay through two multicenter surveillance programs, in 1997 and 1998. Isolates were serotyped and molecular typed by pulsed-field gel electrophoresis (PFGE) and automated ribotyping. Antimicrobial susceptibilities were determined to 19 drugs by reference broth microdilution methods. Ten isolates (21.7%) had cefotaxime MICs > or = 2 microg/ml, whereas 36 (78.3%) had cefotaxime MIC results at 1 microg/ml. All isolates were susceptible to gatifloxacin, levofloxacin, and vancomycin. The isolates were distributed among five major serotypes (%): 23F (39.1%), 14 (32.6%), 19F (23.9%), 9V (2.2%), and 6B (2.2%). However, distinct molecular patterns were detected among isolates with a unique serotype. Six and four PFGE patterns were identified among isolates with serotype 23F and 19F, respectively. When PFGE and automated ribotyping analyses were combined, four clusters were identified. The largest cluster (10 isolates) was represented by isolates with ribotype 18-2, major PFGE pattern I, and serotype 14. ATCC 700671 (international clone Spain 9V-3) also showed ribotype 18-2. This clone was detected in four countries: Argentina, Brazil, Chile, and Uruguay. A second cluster (8 isolates) were characterized by isolates with ribotype 17-4, PFGE type D, and serotype 23F, similar to ATCC 700669 (international clone Spain23F-1). Isolates from this cluster were identified in three countries: Brazil, Chile, and Mexico. Our results indicated that clonal dissemination of S. pneumoniae with reduced susceptibility to cefotaxime has occurred in Latin America mainly among serogroups 14, 19F, and 23F.

Skin and soft tissue infections in Latin American medical centers: four-year assessment of the pathogen frequency and antimicrobial susceptibility patterns

We report the results of pathogen frequency and antimicrobial susceptibility of isolates collected from skin and soft tissue infections (SSTIs) in Latin American medical centers during the first 4 years (1997-2000) of the SENTRY Antimicrobial Surveillance Program. Ten laboratories participated each year distributed among nine cities in six countries. A total of 1,789 bacterial isolates were susceptibility tested by reference broth microdilution at the coordinating central laboratory. Results from isolates collected during the year 2000 were compared with those from isolates collected during the prior three years. Selected carbapenem-resistant Pseudomonas aeruginosa were genotyped by automated ribotyping to evaluate the occurrence of clonal, epidemic dissemination. The five most frequently isolated species were (n/%): Staphylococcus aureus (584/32.8%), Escherichia coli (233/13.1%), P. aeruginosa (211/11.9%), Enterococcus spp. (137/7.7%), and Klebsiella spp. (127/5.8%). The most problematic antimicrobial resistances were related to the high prevalence of multi-drug resistant (MDR) Gram-negative bacilli. Carbapenem resistance among non-fermentative Gram-negative bacilli was much higher than that reported in other regions evaluated in the SENTRY Program. Only 74.9% of P. aeruginosa and 84.9% of Acinetobacter spp. were considered susceptible to imipenem. The antimicrobial susceptibility rates of P. aeruginosa decreased during the study period for most antimicrobial agents evaluated. More than 40% of K. pneumoniae and nearly 10% of E. coli showed an extended spectrum β-lactamase phenotype. Only 73.4% of E. coli and 76.0% of Enterobacter spp. were susceptible to ciprofloxacin. The molecular typing of carbapenem-resistant P. aeruginosa demonstrated clonal dissemination in two institutions. These reported results indicate that rates of resistance among isolates causing SSTI continue to raise in Latin America, with specific concerns for the high prevalence of MDR Gram-negative bacilli. National and international surveillance programs as a guide to focusing intervention strategies should assist in the control of escalating antimicrobial resistance in this geographic area.

Four-year evaluation of frequency of occurrence and antimicrobial susceptibility patterns of bacteria from bloodstream infections in Latin American medical centers

As part of the Latin American arm of the SENTRY Antimicrobial Surveillance Program, 7,207 bacterial isolates collected consecutively from bloodstream infections (BSI) during the period of January 1997 through December 2000 were analyzed. Ten Latin American laboratories located in six countries participated in the study during each year. Antimicrobial susceptibility testing was performed using the reference NCCLS broth microdilution method. The most frequently isolated species were (n/%): Staphylococcus aureus (1,532/21.3%), Escherichia coli (1,239/17.2%), coagulase-negative Staphylococcus (1,002/13.9%), Klebsiella pneumoniae (664/9.2%), and Pseudomonas aeruginosa (470/6.5%). The prevalence of S. aureus as a cause of BSI increased from 20.5% in 1997 to 23.3% in 2000 ( p = 0.011), but oxacillin-resistance rates remained relatively stable during this period (around 30%). Enterococci (216 isolates) showed low rates of resistance to both vancomycin (2.4%) and ampicillin (7.9%) and 72.7% of 289 Streptococcus pneumoniae isolates evaluated were susceptible to penicillin (MIC ≤0.06 μg/mL). Resistance rates among Gram-negative bacilli were much higher than those reported in other regions evaluated in the SENTRY Program. The main antimicrobial resistance problems among these pathogens were the high prevalences of ESBL-producing E. coli (6.7%) and K. pneumoniae (47.3%), and carbapenem-resistance among P. aeruginosa (around 12%) and Acinetobacter spp. (around 10%). P. aeruginosa resistance rates to meropenem, piperacillin/tazobactam, amikacin, and ciprofloxacin showed a significant increase during the 4-year period evaluated. Resistance rates varied according to the country for several pathogen-antimicrobial combinations. In summary, resistance to most antimicrobial agents for a number of species implicated in bacteremia, especially among Gram-negative rods, has reached worrisome levels and continues to increase.

Urinary tract infection trends in Latin American hospitals: report from the SENTRY antimicrobial surveillance program (1997–2000)

Urinary tract infections (UTI) are one of the most common infectious diseases diagnosed in outpatients as well as in hospitalized patients. The objective of this study was to report the frequency of occurrence and antimicrobial susceptibility of uropathogens collected in Latin America between 1997 to 2000 through the SENTRY Antimicrobial Surveillance Program. Antimicrobial susceptibility testing was performed and results interpreted using reference broth microdilution methods. In the 4 year period, a total of 1961 urine isolates from hospitalized patients were included. The patients’ mean age was 51.3 years and most of the infections occurred among women (65.6%). Esherichia coli was the most frequent pathogen isolated followed by Klebsiella spp., Pseudomonas aeruginosa, and Proteus mirabilis. Among the E. coli isolates, piperacillin/tazobactam, aztreonam, extended-spectrum cephalosporins, carbapenems and amikacin constitute reasonable therapeutic options for treatment of serious UTI in Latin America (91.0–100.0% susceptible). High resistance rates to fluoroquinolones (17.5–18.9%) and trimethoprim/sulfamethoxazole (>45.0%) were observed among the E. coli. In contrast, nitrofurantoin displayed susceptibility rate of > 87.0%. Against Klebsiella spp. infections, the only effective therapeutic option would be the carbapenems due to the high number of isolates (>30.0%) producing extended-spectrum β-lactamases (ESBL). Even the new fluoroquinolones showed limited activity against Klebsiella spp. (72.1–88.6% susceptible) and the P. aeruginosa isolates showed high resistance rates to most antimicrobial agents tested. The results of this survey endorse the importance of Enterobacteriaceae as cause of UTI in Latin America. Our results also demonstrate that the uropathogens isolated in the Latin American medical centers exhibit high resistance to various classes of antimicrobial agents. Carbapenem-resistant P. aeruginosa, ciprofloxacin-resistant E. coli, ESBL-producing K. pneumoniae constitute serious problem in this geographic region.

Salmonella spp. isolates causing bloodstream infections in Latin America: report of antimicrobial activity from the SENTRY Antimicrobial Surveillance Program (1997–2000)

Recent years have seen a dramatic rise in the incidence and severity of cases of human salmonellosis. In addition, multidrug resistant strains have arisen. The objective of this study was to characterize the antimicrobial susceptibility profile of Salmonella spp. clinical isolates collected from Latin American medical centers as part of the SENTRY Antimicrobial Surveillance System. A total of 144 bloodstream Salmonella spp. isolates were collected between 1997 and 2000. The susceptibility to diverse antimicrobial agents was tested by broth microdilution techniques according to the NCCLS recommendations. The Salmonella spp. strains were more frequently collected from adult patients (67.0%; 21-60 years) and isolated from Chile (28.5%) > Brazil (25.0%) > Mexico (18.8%) > Colombia (11.8%). Ampicillin (MIC 50, 1μg/ml) showed good in vitro activity (92.4% susceptibility). Meropenem (MIC 50, 0.06 μg/ml) and gatifloxacin (MIC 50, 0.03 μg/ml) were the most potent compounds against the Salmonella spp. isolates (100.0% susceptible) followed by piperacillin/tazobactam (99.3%), ceftazidime (98.6%), ceftriaxone (98.6%), and amoxicillin/clavulanic acid (94.4%). The lowest susceptibility rates were observed for tetracycline (87.5%) and trimethoprim/sulfamethoxazole (91.7%). Four of 144 (2.8%) Salmonella spp. isolates demonstrated an ESBL phenotype; however, only two (1.4%) were confirmed as an inhibitable ESBL producer. The results of this study show that multidrug resistance, especially fluoroquinolone resistance, does not represent a serious problem among Salmonella isolates collected from the Latin American medical centers as monitored by the SENTRY Program.

Respiratory tract pathogens isolated from patients hospitalized with suspected pneumonia in Latin America: frequency of occurrence and antimicrobial susceptibility profile: results from the SENTRY Antimicrobial Surveillance Program (1997-2000)

In spite of the recent medical advances, lower respiratory tract infections are still the most frequent infectious causes of mortality worldwide. The objective of this study was to determine the frequency of occurrence and antimicrobial susceptibility of bacterial isolates collected from hospitalized patients with pneumonia in Latin American medical centers during the first four years of the SENTRY Program. The five most frequently isolated species were (n/%): Pseudomonas aeruginosa (659/26.3%), Staphylococcus aureus (582/23.3%), Klebsiella pneumoniae (255/10.2%), Acinetobacter spp. (239/9.6%), and Enterobacter spp. (134/5.4%). P. aeruginosa demonstrated high rates of resistance to most of the antimicrobials tested. Against P. aeruginosa, the most active agents were meropenem (MIC 50, 1 μg/ml; 71.6% susceptible), amikacin (MIC 50, 4 μg/ml; 71.0% susceptible), and piperacillin/tazobactam (MIC 50, 16 μg/ml; 70.4% susceptible). Imipenem (MIC 50, 1 μg/ml; 84.1% susceptible) and meropenem (MIC 50, 2 μg/ml; 84.9% susceptible) were the most active agents against Acinetobacter spp. followed by tetracycline (MIC 50, ≤4 μg/ml; 52.3% susceptible). Although the broad-spectrum cephalosporins had demonstrated excellent in vitro activity against Klebsiella pneumoniae isolates (MIC 50s range, ≤ 0.12 to 0.25 μg/ml), elevated rates of resistance (46.3%-58.5%) were observed. Approximately 44.0% and 29.0% of K. pneumoniae and E. coli isolates were considered ESBL producers based on NCCLS criteria, respectively. Overall, the prevalence of methicillin-resistant S. aureus was 46.2%. The most active drugs against this pathogen were vancomycin, teicoplanin, linezolid and quinupristin/dalfopristin. In summary, the SENTRY Antimicrobial Surveillance Program has detected a high prevalence of methicillin-resistant S. aureus and multidrug resistant non-fermentative Gram-negative bacilli isolated from respiratory tract specimens of hospitalized patients with pneumonia in Latin America. Our results emphasize the importance of local surveillance programs in correctly guiding empiric therapy and local intervention programs in attempt to reduce antimicrobial resistance.

Multicenter assessment of the linezolid spectrum and activity using the disk diffusion and Etest methods: report of the Zyvox® Antimicrobial Potency Study in Latin America (LA-ZAPS)

Linezolid was the first clinically applied member of the new antimicrobial class called the oxazolidinones. These agents have a powerful spectrum of activity focussed against Gram-positive organisms including strains with documented resistances to other antimicrobial classes. We conducted a multicenter surveillance (Zyvox Antimicrobial Potency Study; ZAPS) trial of qualifying Gram-positive isolates from 24 medical centers in eight countries in Latin America. The activity and spectrum of linezolid was compared to numerous agents including glycopeptides, quinupristin/dalfopristin, beta-lactams and fluoroquinolones when testing 2,640 strains by the standardized disk diffusion method or Etest (AB BIODISK, Solna, Sweden). The linezolid spectrum was complete against staphylococci (median zone diameter, 29 - 32 mm), as was the spectrum of vancomycin and quinupristin/dalfopristin. Among the enterococci, no linezolid resistance was detected, and the susceptibility rate was 93.1 - 96.4%. Only the vancomycin-susceptible Enterococcus faecium strains remained susceptible (92.8%) to quinupristin/dalfopristin. Marked differences in the glycopeptide resistance patterns (van A versus van B) were noted for the 22 isolates of VRE, thus requiring local susceptibility testing to direct therapy. Streptococcus pneumoniae and other species were very susceptible (100.0%) to linezolid, MIC(90) at 0.75 microg/ml. Penicillin non-susceptible rate was 27.7% and erythromycin resistance was at 17.4%. Other streptococci were also completely susceptible to linezolid (MIC(90), 1 microg/ml). These results provide the initial benchmark of potency and spectrum for linezolid in Latin American medical centers. Future comparisons should recognize that the oxazolidinones possess essentially a complete spectrum coverage of the monitored staphylococci, enterococci and streptococcal isolates in 2000-2001. This positions linezolid as the widest spectrum empiric choice against multi-resistant Gram-positive cocci, a spectrum of activity greater than available glycopeptides and the streptogramin combination.