Rayo Morfin-Otero

First Report of Staphylococcal Clinical Isolates in Mexico with Linezolid Resistance Caused by cfr: Evidence of In Vivo cfr Mobilization

An oxazolidinone resistance mechanism (Cfr) was recently described in human isolates of staphylococci ([18][1]). Cfr causes posttranscriptional methylation of the 23S rRNA (A2503), affecting drugs belonging to several antimicrobial classes ([10][2]). cfr -carrying isolates recovered from human

Metallo-β-Lactamase Gene blaIMP-15 in a Class 1 Integron, In95, from Pseudomonas aeruginosa Clinical Isolates from a Hospital in Mexico

ABSTRACT During 2003, 40 carbapenem-resistant Pseudomonas aeruginosa clinical isolates collected in a Mexican tertiary-care hospital were screened for metallo-β-lactamase production. Thirteen isolates produced IMP-15, and 12 had a single pulsed-field gel electrophoresis pattern. The blaIMP-15 gene cassette was inserted in a plasmid-borne integron with a unique array of gene cassettes and was named In95.

Staphylococcal cassette chromosome mec (SCC mec) in methicillin-resistant coagulase-negative staphylococci. A review and the experience in a tertiary-care setting.

Coagulase-negative staphylococci (CNS) are increasingly recognized to cause clinically significant infections, with S. epidermidis often cited as the third most common cause of nosocomial sepsis. Among CNS, there is a high prevalence of methicillin resistance associated with staphylococcal cassette chromosome (SCCmec) elements. Although identical SCCmec types can exist in S. aureus and CNS, some novel classes of SCCmec may be unique to CNS. Differences in the accuracy of identification of CNS species and use of non-standardized methods for the detection of methicillin resistance have led to confusing data in the literature. In addition to the review of SCCmec in CNS, in this paper we report a 2-year surveillance of methicillin-resistant CNS in a tertiary-care hospital in Guadalajara, Mexico.

Acceptance of a Vaccine Against Novel Influenza A (H1N1) Virus Among Health Care Workers in Two Major Cities in Mexico

BACKGROUND AND AIMS Further cases of novel influenza A (H1N1) outbreak are expected in the coming months. Vaccination has been proven to be essential to control a pandemic of influenza; therefore, considerable efforts and resources have been devoted to develop a vaccine against the influenza A (H1N1) virus. With the current availability of the vaccine, it will be important to immunize as many people as possible. However, previous data with seasonal influenza vaccines have shown that there are multiple barriers related to perceptions and attitudes of the population that influence vaccine use. The aim of the study was to evaluate the acceptance of a newly developed vaccine against pandemic (H1N1) 2009 influenza A among healthcare workers (HCW) in Mexico. METHODS We conducted a cross-sectional study among HCW in three hospitals in the two largest cities in Mexico-Mexico City and Guadalajara-between June and September 2009. RESULTS A total of 1097 HCW participated in the survey. Overall, 80% (n = 880) intended to accept the H1N1 pandemic vaccine and 71.6% (n = 786) reported they would recommend the vaccine to their patients. Doctors were more likely to accept and recommend the vaccine than nurses. HCWs who intend to be immunized will be more likely to do so if they know that the vaccine is safe and effective. CONCLUSIONS Knowledge of the willingness to accept the vaccine can be used to plan strategies that will effectively respond to the needs of the population studied, reducing the health and economic impact of novel influenza A (H1N1) virus.

Phenotypes and genotypes of erythromycin-resistant Streptococcus pyogenes strains isolated from invasive and non-invasive infections from Mexico and the USA during 1999-2010 §

OBJECTIVE To compare the prevalence, phenotypes, and genes responsible for erythromycin resistance among Streptococcus pyogenes isolates from Mexico and the USA. METHODS Eighty-nine invasive and 378 non-invasive isolates from Mexico, plus 148 invasive, 21 non-invasive, and five unclassified isolates from the USA were studied. Susceptibilities to penicillin, erythromycin, clindamycin, ceftriaxone, and vancomycin were evaluated according to Clinical and Laboratory Standards Institute (CLSI) standards. Phenotypes of erythromycin resistance were identified by triple disk test, and screening for mefA, ermTR, and ermB genes was carried out by PCR. RESULTS All isolates were susceptible to penicillin, ceftriaxone, and vancomycin. Erythromycin resistance was found in 4.9% of Mexican strains and 5.2% of USA strains. Phenotypes in Mexican strains were 95% M and 5% cMLS; in strains from the USA, phenotypes were 33.3% iMLS, 33.3% iMLS-D, and 33.3% M. Erythromycin resistance genes in strains from Mexico were mefA (95%) and ermB (5%); USA strains harbored ermTR (56%), mefA (33%), and none (11%). In Mexico, all erythromycin-resistant strains were non-invasive, whereas 89% of strains from the USA were invasive. CONCLUSIONS Erythromycin resistance continues to exist at low levels in both Mexico and the USA, although the genetic mechanisms responsible differ between the two nations. These genetic differences may be related to the invasive character of the S. pyogenes isolated.

Changes in MIC Within a Global Collection of Acinetobacter baumannii Collected as Part of the Tigecycline Evaluation and Surveillance Trial, 2004 to 2009

BACKGROUND The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) began in 2004 to monitor global antimicrobial susceptibility to tigecycline and a range of comparator antimicrobials among gram-positive and gram-negative organisms. OBJECTIVE The aim of this study was to report changes in MIC for tigecycline and other antimicrobial agents among 10,149 Acinetobacter baumannii isolates collected globally between 2004 and 2009. METHODS MICs of 10,149 isolates were determined locally using Clinical Laboratory and Standards Institute (CLSI) methodologies. Antimicrobial susceptibility was ascertained according to CLSI interpretive criteria (no interpretive criteria have been approved for tigecycline against Acinetobacter spp). RESULTS Increases in resistance were noted for most antimicrobial agents in all regions. Significant (P < 0.05) increases in percentage resistance were reported for all antimicrobial agents globally. The smallest changes in cumulative geometric mean MICs were reported for tigecycline (0.2 mg/L) and cefepime (3.5 mg/L). MIC(90)s were at the top of their testing ranges for most agents against both multidrug-resistant (MDR) and non-MDR isolates; only tigecycline showed little change in MIC(90) between MDR (2 mg/L) and non-MDR (1 mg/L) isolates. Resistance was higher among isolates from the intensive care unit (ICU) compared with non-ICU isolates. CONCLUSION These findings suggest that resistance is increasing among clinical isolates of A baumannii globally. Although resistance to tigecycline has been reported in the treatment of infections caused by A baumannii, it retains in vitro activity against this pathogen.

Dissemination of a blaVIM-2-Carrying Integron Among Enterobacteriaceae Species in Mexico: Report from the SENTRY Antimicrobial Surveillance Program

Three VIM-2-producing Enterobacteriaceae (two Enterobacter cloacae and one Klebsiella oxytoca) isolates recovered from patients in a Mexican hospital were characterized during the SENTRY Antimicrobial Surveillance Program (2005-2007). These strains carried identical bla(VIM-2) integrons in a 450-kb plasmid. The interspecies dissemination of this bla(VIM-2)-harboring element emphasizes the potential for spread of genetic structures carrying metallo-beta-lactamases that could limit therapeutic options in this geographic region.

Species distribution and antifungal susceptibility of bloodstream fungal isolates in paediatric patients in Mexico: a nationwide surveillance study

OBJECTIVES To establish the species distribution and in vitro susceptibilities of 358 bloodstream fungal isolates from paediatric patients in Mexico. METHODS Isolates were collected during a 2 year surveillance programme in 14 medical centres in 10 Mexican states. A molecular approach was used to determine the Candida parapsilosis species complex. In vitro susceptibility to amphotericin B, fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, anidulafungin and micafungin was determined according to CLSI procedures. Species-specific clinical breakpoints for fluconazole, voriconazole and echinocandins were applied. RESULTS Candida spp. accounted for 98.33% of fungaemias, including 127 Candida albicans isolates, 127 C. parapsilosis complex isolates (121 C. parapsilosis sensu stricto, 4 Candida orthopsilosis and 2 Candida metapsilosis strains) and 72 Candida tropicalis isolates. C. albicans and C. parapsilosis complex were the species predominant in neonates (48 cases each; 41.02%). C. parapsilosis complex was also the predominant species in patients 1 month to <2 years of age (P = 0.007). In contrast, C. albicans was the most frequent species in patients aged 2 to <12 years (P = 0.003). Antifungal resistance was rare among the subset of isolates. Candida glabrata showed the highest resistance rate to amphotericin B (1/9 isolates), fluconazole (1/9 isolates) and itraconazole (2/9 isolates). CONCLUSIONS The species distribution differed with the age of the patients, with C. albicans and C. parapsilosis complex being the most commonly isolated species. C. glabrata showed the highest resistance rate to amphotericin B, fluconazole and itraconazole. This is the first study of fungaemia episodes in Mexican children.

Resistance trends in gram-negative bacteria: surveillance results from two Mexican hospitals, 2005–2010

BackgroundHospital-acquired infections caused by multiresistant gram-negative bacteria are difficult to treat and cause high rates of morbidity and mortality. The analysis of antimicrobial resistance trends of gram-negative pathogens isolated from hospital-acquired infections is important for the development of antimicrobial stewardship programs. The information obtained from antimicrobial resistant programs from two hospitals from Mexico will be helpful in the selection of empiric therapy for hospital-acquired gram-negative infections.FindingsTwo thousand one hundred thirty two gram-negative bacteria collected between January 2005 and December 2010 from hospital-acquired infections occurring in two teaching hospitals in Mexico were evaluated. Escherichia coli was the most frequently isolated gram-negative bacteria, with >50% of strains resistant to ciprofloxacin and levofloxacin. Klebsiella spp. showed resistance rates similar to Escherichia coli for ceftazidime (33.1% vs 33.2%), but exhibited lower rates for levofloxacin (18.2% vs 56%). Of the samples collected for the third most common gram-negative bacteria, Pseudomonas aeruginosa, >12.8% were resistant to the carbapenems, imipenem and meropenem. The highest overall resistance was found in Acinetobacter spp. Enterobacter spp. showed high susceptibility to carbapenems.ConclusionsE. coli was the most common nosocomial gram-negative bacilli isolated in this study and was found to have the second-highest resistance to fluoroquinolones (>57.9%, after Acinetobacter spp. 81.2%). This finding represents a disturbing development in a common nosocomial and community pathogen.

Microbiological and molecular characterization of human clinical isolates of Staphylococcus cohnii, Staphylococcus hominis, and Staphylococcus sciuri

Abstract Background: The incidence of coagulase-negative staphylococci reported as causative agents of nosocomial infections has risen in the last decade. The aim of this study was to characterize biofilm formation, antibiotic resistance, SCCmec type, and genetic relatedness in clinical isolates of Staphylococcus cohnii, Staphylococcus hominis, and Staphylococcus sciuri recovered from humans. Methods: Clinically relevant isolates of S. cohnii (n = 15), S. hominis (n = 9), and S. sciuri (n = 6), were collected from patients. Biofilm formation was evaluated using crystal violet staining, drug susceptibility was assessed using the broth microdilution method, and methicillin resistance was measured using the cefoxitin disk test. SCCmec was typed using 2 different methodologies, and genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE). Results: Sixty percent (9/15) of S. cohnii, 33% (3/9) of S. hominis, and 50% (3/6) of S. sciuri isolates were categorized as weak producers of biofilm. None of the isolates were resistant to vancomycin or linezolid. All 3 species showed a high resistance (> 66%) to ampicillin, levofloxacin, erythromycin, and ceftriaxone, and the majority of the isolates were methicillin-resistant. PFGE revealed that the S. cohnii isolates comprised 1 dominant clone. Conclusions: The S. cohnii, S. hominis, and S. sciuri isolates analyzed in this study showed a high methicillin resistance and resistance to other antimicrobials. The results of this study strongly suggest that coagulase-negative staphylococci harbour new SCCmec elements. We report the first case of a clone of S. cohnii associated with human disease.