Non-fermenter Gram-negative bacilli at a tertiary hospital, South Africa.

Background: Non-fermenting Gram-negative bacilli (NFGNB) are a significant cause of healthcare-associated infections and are often implicated in nosocomial outbreaks. Non- fermenting Gram-negative bacilli tend to have variable susceptibility patterns that make the choice of empiric therapy difficult and thus treatment must be based on in vitro susceptibility testing of each antimicrobial agent. Objectives: To describe the epidemiology of the NFGNB isolated from adult patients at Chris Hani Baragwanath Hospital (CHBAH) and to assess their antimicrobial susceptibility patterns in order to guide empiric therapy and inform infection prevention and control practices. Method: Organisms isolated from sterile sites of adult in-patients between 01 January 2016 to 31 December 2018 were retrospectively analysed. Results: A total of 2005 NFGNB isolated. Blood cultures were the most common specimen type (91.4%). Acinetobacter species were the most commonly isolated organisms (65.1%), followed by Pseudomonas species (26.5%). The majority of NFGNB were isolated from patients in surgical wards (38.9%) followed by medical wards (35.2%). Most (60%) of the Acinetobacter species were extremely drug resistant. Pseudomonas species were more susceptible than the Acinetobacter species with an overall susceptibility rate of 86% for Pseudomonas species. Conclusion: The rates of antimicrobial resistance demonstrated among Acinetobacter and Pseudomonas species were high, which illustrates the threat of antimicrobial resistance also seen worldwide. An emergence of NFGNB with intrinsic multidrug resistance (Stenotrophomonas maltophilia and Burkholderia cepacia) was noted. We suggest empiric therapy with a carbapenem sparing regimen of piperacillin-tazobactam in combination with amikacin and that empiric therapy be reviewed annually when cumulative antibiograms are done. Contribution: Understanding of the distribution and antimicrobial susceptibility patterns of NFGNB at CHBAH.

The Role of Automation for Early Diagnosis of Non-fermenter Superbugs in Critically Ill Septicemic Hospitalized Patients.

Introduction Non-fermenting Gram-negative bacilli (NFGNB) are emerging superbugs of bloodstream infections (BSI), causing increased mortality in hospitalized patients. NFGNB are challenging to identify using conventional identification techniques. Hence, automation is beneficial for accurate and fast diagnosis; it also facilitates rapid treatment and recovery of patients. This study aims to isolate/identify NFGNB from BSI and determine its antimicrobial susceptibility pattern. Material and methods This study was conducted in the Department of Microbiology, LLRMMC, Meerut, for a period of six months (June to November 2022). The samples were processed using automated blood culture (BD BACTEC) and an identification/sensitivity testing system (BD Phoenix). Results Out of 1340 blood cultures, 347 (25.7%) were flagged positive for microbial growth. A total of 103 (7.6%) NFGNB were isolated, showing their strong association with BSI. The NFGNB isolates were Pseudomonas species 23 (22.3%), Acinetobacter baumannii 19 (18.4%), Salmonella spp. 19 (18.4%), Sphingomonas paucimobilis 17 (16.5%), Aeromonas hydrophila 5 (4.8%), Rhizobium radiobacter sp. 4 (3.8%), Stenotrophomonas maltophila 3 (2.9%), Burkholderia cepacian 3 (2.9%), Proteus mirabilis 2 (1.9%), Achromobacter xylosoxidans 2 (1.9%), Elizabethkingia meningoseptica 2 (1.9%), Ochromobacter anthropic 2 (1.9%), Cuprivadus pauculus 1 (0.9%), and Ralstonia mannitolilytica 1 (0.9%). Conclusions Automation helps in the prompt reporting of NFGNB and their antibiogram pattern by microbiology laboratories, facilitating the early and accurate management of patients with BSI.

Whole-Genome Sequencing-Based Resistome Analysis of Nosocomial Multidrug-Resistant Non-Fermenting Gram-Negative Pathogens from the Balkans.

Non-fermenting Gram-negative bacilli (NFGNB), such as Pseudomonas aeruginosa and Acinetobacter baumannii, are among the major opportunistic pathogens involved in the global antibiotic resistance epidemic. They are designated as urgent/serious threats by the Centers for Disease Control and Prevention and are part of the World Health Organization's list of critical priority pathogens. Also, Stenotrophomonas maltophilia is increasingly recognized as an emerging cause for healthcare-associated infections in intensive care units, life-threatening diseases in immunocompromised patients, and severe pulmonary infections in cystic fibrosis and COVID-19 individuals. The last annual report of the ECDC showed drastic differences in the proportions of NFGNB with resistance towards key antibiotics in different European Union/European Economic Area countries. The data for the Balkans are of particular concern, indicating more than 80% and 30% of invasive Acinetobacter spp. and P. aeruginosa isolates, respectively, to be carbapenem-resistant. Moreover, multidrug-resistant and extensively drug-resistant S. maltophilia from the region have been recently reported. The current situation in the Balkans includes a migrant crisis and reshaping of the Schengen Area border. This results in collision of diverse human populations subjected to different protocols for antimicrobial stewardship and infection control. The present review article summarizes the findings of whole-genome sequencing-based resistome analyses of nosocomial multidrug-resistant NFGNBs in the Balkan countries.

Less Is More? Antibiotic Treatment Duration in Pseudomonas aeruginosa Ventilator-Associated Pneumonia.

Recommended antimicrobial treatment durations for ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa have evolved over the past few decades. In this Viewpoint, we provide a narrative review of landmark trials investigating antimicrobial treatment durations for VAP caused by P. aeruginosa, and appraise iterations of expert consensus guidelines based on these data. We highlight strengths and weaknesses of existing data on this topic and provide recommendations for future avenues of study.

An 18-Year Dataset on the Clinical Incidence and MICs to Antibiotics of Achromobacter spp. (Labeled Biochemically or by MAL-DI-TOF MS as A. xylosoxidans), Largely in Patient Groups Other than Those with CF.

Achromobacter spp. are intrinsically multidrug-resistant environmental microorganisms which are known to cause opportunistic, nosocomial, and sometimes chronic infections. The existing literature yields scarcely any larger datasets, especially with regard to the incidence in patient groups other than those with cystic fibrosis. The aim of this study was to fill this gap. We present a retrospective analysis of 314 clinical and 130 screening isolates detected in our diagnostic unit between 2004 and 2021, combined with patients' demographic and clinical information (ward type and length of hospitalization), and the results of routine diagnostic antibiotic MIC determination. We found the apparent increase in prevalence in our diagnostic unit, in which cystic fibrosis patients are an underrepresented group, in large part to be attributable to an overall increase in the number of samples and, more importantly, changes in the diagnostic setting, such as the introduction of rigorous screening for Gram-negative multidrug-resistant pathogens. We found these Achromobacter spp. to be most commonly detected in urine, stool, wounds and airway samples, and found the resistance rates to vary strongly between different sample types. Intestinal carriage is frequently not investigated, and its frequency is likely underestimated. Isolates resistant to meropenem can hardly be treated.

Impact of sink removal from intensive care unit rooms on the consumption of antibiotics and on results of Zero Resistance Project

IntroductionDue to the favourable impact of removing the sinks on isolations in bronchoaspirate samples of patients with mechanical ventilation, we now evaluate the impact on the consumption of antibiotics as well as on the results of the Zero Resistance Project (ZRP).Patients and methodsAll the patients admitted to the unit in a quasi-experimental before–after study with a pre-intervention period between 2014 and 2016 and a post-intervention period from 2016 to 2017, to evaluate antibiotic consumption in defined daily doses, and until 2018, to evaluate the ZRP indicators. The intervention was the removal of the sinks from the rooms of the ICU. We evaluated antibiotic consumption densities and their ratios, grouped as Enterobacteriaceae and non-fermenting gram-negative bacilli (NFGNB) according to their antibiograms; the absolute number of ‘antibiotic days’, ‘hospitalised days’, ‘isolation days’, and ‘multi-resistant bacteria (MRB) days’; as well as their incidence densities per 1000 hospitalised days and the ratio between the two years prior to and the two years after the intervention.ResultsPost-intervention antibiotic use was 1.61-fold (1.60–1.62) and 2.24-fold (2.10–2.37) lower for antibiotics used against Enterobacteriaceae and NFGNB, respectively. There were also reductions in the number of days of antibiotic use by 1.29-fold (1.22–1.36), number of MRB days by 1.84-fold (1.63–2.08), and number of patient isolation days by 1.51-fold (1.38–1.66).DiscussionThe results suggest that the intervention had a favourable impact on the consumption of antibiotics, as well as on the number of days on antibiotics, MRB, and isolation.

Impact of sink removal from intensive care unit rooms on the consumption of antibiotics and on results of Zero Resistance Project.

INTRODUCTION: Due to the favourable impact of removing the sinks on isolations in bronchoaspirate samples of patients with mechanical ventilation, we now evaluate the impact on the consumption of antibiotics as well as on the results of the Zero Resistance Project (ZRP). PATIENTS AND METHODS: All the patients admitted to the unit in a quasi-experimental before-after study with a pre-intervention period between 2014 and 2016 and a post-intervention period from 2016 to 2017, to evaluate antibiotic consumption in defined daily doses, and until 2018, to evaluate the ZRP indicators. The intervention was the removal of the sinks from the rooms of the ICU. We evaluated antibiotic consumption densities and their ratios, grouped as Enterobacteriaceae and non-fermenting gram-negative bacilli (NFGNB) according to their antibiograms; the absolute number of 'antibiotic days', 'hospitalised days', 'isolation days', and 'multi-resistant bacteria (MRB) days'; as well as their incidence densities per 1000 hospitalised days and the ratio between the two years prior to and the two years after the intervention. RESULTS: Post-intervention antibiotic use was 1.61-fold (1.60-1.62) and 2.24-fold (2.10-2.37) lower for antibiotics used against Enterobacteriaceae and NFGNB, respectively. There were also reductions in the number of days of antibiotic use by 1.29-fold (1.22-1.36), number of MRB days by 1.84-fold (1.63-2.08), and number of patient isolation days by 1.51-fold (1.38-1.66). DISCUSSION: The results suggest that the intervention had a favourable impact on the consumption of antibiotics, as well as on the number of days on antibiotics, MRB, and isolation.

In Vitro Activity of 22 Antibiotics against Achromobacter Isolates from People with Cystic Fibrosis. Are There New Therapeutic Options?

Bacteria belonging to the genus Achromobacter are increasingly isolated from respiratory samples of people with cystic fibrosis (PWCF). The management of this multidrug-resistant genus is challenging and characterised by a lack of international recommendations, therapeutic guidelines and data concerning antibiotic susceptibility, especially concerning the newer antibiotics. The objective of this study was to describe the antibiotic susceptibility of Achromobacter isolates from PWCF, including susceptibility to new antibiotics. The minimum inhibitory concentrations (MICs) of 22 antibiotics were determined for a panel of 23 Achromobacter isolates from 19 respiratory samples of PWCF. Two microdilution MIC plates were used: EUMDROXF® plate (Sensititre) and Micronaut-S Pseudomonas MIC® plate (Merlin) and completed by a third method if necessary (E-test® or UMIC®). Among usual antimicrobial agents, the most active was imipenem (70% susceptibility). Trimethoprim-sulfamethoxazole, piperacillin and tigecycline (65%, 56% and 52% susceptibility, respectively) were still useful for the treatment of Achromobacter infections. Among new therapeutic options, ß-lactams combined with a ß-lactamase-inhibitor did not bring benefits compared to ß-lactam alone. On the other hand, cefiderocol appeared as a promising therapeutic alternative for managing Achromobacter infections in PWCF. This study provides the first results on the susceptibility of clinical Achromobacter isolates concerning new antibiotics. More microbiological and clinical data are required to establish the optimal treatment of Achromobacter infections.

Detection and Characterization of Clinical Bordetella trematum Isolates from Chronic Wounds.

Bordetella trematum is a relatively newly discovered and potentially frequently overlooked Bordetella species, mostly isolated from chronic wounds and predominantly in those of the lower extremities. Its susceptibility profile and clinical significance is still debated, given the limited amount of available data. We contribute providing a molecular and phenotypical analysis of three unique clinical B. trematum isolates detected between August 2019 and January 2020 to aid the matter. Cryo-conserved isolates were subcultured and re-identified using various routine means of identification. Bacterial genomes were fully Illumina-sequenced and phenotypical susceptibility was determined by broth microdilution and gradient-strip tests. All isolates displayed increased susceptibility to piperacillin-tazobactam (<2/4 mg/L), imipenem (<1 mg/L), and meropenem (<0.047 mg/L), whereas they displayed decreased susceptibility to all tested cephalosporins and fluoroquinolones (according to PK-PD, EUCAST 10.0 2020). One isolate carried a beta-lactamase (EC 3.5.2.6) and a sulfonamide resistance gene (sul2) and cells displayed resistance to ampicillin, ampicillin/sulbactam, and trimethoprim/sulfamethoxazole. All isolates carried genes conferring decreased susceptibility to aminoglycosides (aadA), fosfomycin (fosA) and fluoroquinolones (gyrB EC 5.99.1.3). Awareness that B. trematum can be resistant to trimethoprim/sulfamethoxazole is warranted.

Genomic analysis of carbapenem-resistant Pseudomonas aeruginosa ST143 clone showing susceptibility to broad-spectrum cephalosporins.

OBJECTIVES: Using whole-genome sequencing (WGS), we aimed to characterise a Pseudomonas aeruginosa ST143 clinical strain (Pb9) that presented resistance to meropenem and imipenem and susceptibility to piperacillin/tazobactam and broad-spectrum cephalosporins. METHODS: The antimicrobial susceptibility profile was confirmed by broth microdilution. WGS was performed using an Illumina MiSeq platform to identify possible genetic determinants of ß-lactam resistance. Transcription levels of chromosomally encoded efflux systems and oprD were evaluated by RT-qPCR. RESULTS: WGS analysis showed that no acquired carbapenemase-encoding gene was found in isolate Pb9, although mutations in the chromosomally encoded ß-lactamase genes blaOXA-488, blaPIB-1 and blaPDC-5 were observed. In addition, we detected a premature stop codon in the major porin-encoding gene oprD coupled with hyperexpression of MexAB-OprM and MexEF-OprN. CONCLUSION: Our results suggest that the ß-lactam resistance phenotype presented by strain Pb9 might be related to an association of OprD loss with hyperexpression of the efflux pump systems MexAB-OprM and MexEF-OprN. However, the contribution of OXA-488, PDC-5 and PIB-1 to this phenotype remains unclear and warrants further investigation.

Evaluation of Vitek-MS™ and Microflex LT™ commercial systems for identification of Acinetobacter calcoaceticus-baumannii complex.

INTRODUCTION: Acinetobacter is a genus that comprises a group of opportunistic pathogens responsible for a variety of nosocomial infections. The Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex includes some species of clinical importance, mainly A. baumannii, A. pittii and A. nosocomialis, which share phenotypic similarities that make it very difficult to distinguish between them using a phenotypic approach. The aim of this study was to evaluate two commercial matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems for the identification of different Acinetobacter species, with a special focus among those belonging to the Acb complex. METHODS: One hundred and fifty-six Acinetobacter spp. clinical strains, identified by amplified ribosomal DNA restriction analysis (ARDRA) and rpoB gene sequencing, were analysed by two different MALDI-TOF systems. RESULTS: Considering only the 144 strains of the Acb complex evaluated in this study, the Vitek-MS™ and Microflex LT™ systems correctly identified 129 (89.6%) and 143 (99.3%) strains, respectively. CONCLUSION: After analysing 156 strains belonging to Acinetobacter spp., both Vitek-MS™ and Microflex LT™ proved to be rapid and accurate systems for the identification of Acb complex species showing a good correlation. However, both manufacturers should improve their databases to include new species in them.

Comparisons of clinical features and outcomes between Elizabethkingia meningoseptica and other glucose non-fermenting Gram-negative bacilli bacteremia in adult ICU patients.

BACKGROUND: Clinical information of Elizabethkingia meningoseptica (EM) bacteremia in intensive care unit (ICU) patients is limited and the impact on outcomes uncertain. The aim of this study was to investigate the clinical features and impact of EM bacteremia compared to other glucose non-fermenting Gram-negative bacilli (GNF-GNB) bacteremia in ICU patients. METHODS: This retrospective cohort study enrolled 70 patients who developed GNF-GNB bacteremia after ICU admission, including 19 cases of EM bacteremia (19/70, 27.1%). The main outcome measure was in-hospital mortality. RESULTS: The patients with EM bacteremia had a lower rate of appropriate antibiotic therapy (15.8% vs. 62.7%, p < 0.001) and a longer time to appropriate antibiotic therapy (76.8 ± 46.4 vs. 35.1 ± 38.7 h, p < 0.001), but with a less severity in acute physiology and chronic health evaluation (APACHE) II score and shock status (p < 0.05) at the onset of bacteremia, compared to those with non-EM bacteremia. The in-hospital mortality between those with EM bacteremia and non-EM bacteremia was similar (63.2% vs. 51.0%, p = 0.363). However, primary bacteremia was more frequently noted in EM compared with non-EM group (57.9% vs. 25.5%, p = 0.011), and odds ratio 4.294 (95% confidence interval 1.292-14.277, p = 0.017) in multivariate regression analysis. CONCLUSION: Among the patients with GNF-GNB bacteremia, the numbers of the cases with primary bacteremia and inappropriate therapy were significantly more in EM group than those in non-EM group.

High Prevalence of Antimicrobial Resistance Among Gram-Negative Isolated Bacilli in Intensive Care Units at a Tertiary-Care Hospital in Yucatán Mexico.

Background and Objectives: Antimicrobial resistance (AMR) is increasing worldwide and imposes significant life-threatening risks to several different populations, especially to those in intensive care units (ICU). The most commonly isolated organisms in ICU comprise gram-negative bacilli (GNB), and these represent a leading cause of serious infections. This study was conducted to describe the prevalence of resistance in GNB isolated from patients in adults, pediatric, and neonatal ICU in a tertiary-care hospital in Mérida, Mexico. Materials and Methods: A retrospective study was done on samples collected in Neonatal (NICU), Pediatric (PICU) and Adult (AICU) ICU of Unidad Médica de Alta Especialidad, Instituto Mexicano del Seguro Social in Mérida, México. The identification of isolates and antimicrobial susceptibility testing were performed using an automated system. Results: A total of 517 GNB strains were isolated. The most common positive culture was bronchial secretions. Pseudomonas aeruginosa was the prevalent pathogen in NICU and PICU, whereas Escherichia coli was common in the AICU. Overall, GNB exhibited a high resistance rates for Ampicillin (95.85%), Cefuroxime (84.17%), Piperacillin (82.93%), Cefotaxime (78.07%), Ceftriaxone (77.41%), Aztreonam (75.23%), Cefazolin (75.00%), and Ceftazidime (73.19%). There are significant differences in the resistance rates of GNB from different ICUs for penicillins, cephalosporins, carbapenems and fluoroquinolones drugs. Escherichia coli (multidrug-resistant [MDR] = 91.57%, highly resistant microorganisms [HRMO] = 90.36%) and Acinetobacter baumannii (MDR = 86.79%, HRMO = 83.02%) exhibited the highest percentage of MDR and HRMO profiles. The prevalence of the extended-spectrum beta-lactamases (ESBL)-producing isolates was 83.13% in E. coli, 78.84% in Klebsiella pneumoniae, and 66.67% in Proteus mirabilis, respectively. Conclusions: The high resistance rates to drugs were exhibited by our GNB isolates. Continuous surveillance and control of the use of antimicrobials are urgently needed to reduce the emergence and spreading of MDR, HRMO, and/or ESBL-producing bacilli.

Comparison of clinical characteristics of bacteremia from Elizabethkingia meningoseptica and other carbapenem-resistant, non-fermenting Gram-negative bacilli at a tertiary medical center.

BACKGROUND: Acquired carbapenem resistance among non-fermenting Gram-negative bacilli (NFGNB), such as Pseudomonas aeruginosa and Acinetobacter calcoaceticus-Acinetobacter baumannii complex (ACB complex), is a serious problem in nosocomial infections. We previously reported that patients infected with the intrinsically carbapenem-resistant Elizabethkingia meningoseptica were associated with high mortality. However, little information is available regarding the clinical outcome of E. meningoseptica bacteremia when compared to that of other carbapenem-resistant NFGNB. METHODS: We conducted an observational study that included consecutive patients with E. meningoseptica, carbapenem-resistant ACB complex, carbapenem-resistant P. aeruginosa, and Stenotrophomonas maltophilia bacteremia at a Taiwanese medical center in 2015. We compared the clinical characteristics and outcomes between patients with E. meningoseptica bacteremia and those with other carbapenem-resistant NFGNB bacteremia. RESULTS: We identified 30 patients with E. meningoseptica, 71 with carbapenem-resistant ACB complex, 25 with S. maltophilia, and 17 with carbapenem-resistant P. aeruginosa bacteremia. The clinical characteristics, disease severity, and previous antibiotic exposures were similar between patients with bacteremia either due to E. meningoseptica or other carbapenem-resistant NFGNB. Patients with E. meningoseptica bacteremia had a higher rate of appropriate empirical antibiotics than those with other carbapenem-resistant NFGNB and was less associated with central venous catheterization. The 28-day mortality rates were similar between patients with E. meningoseptica and the other carbapenem-resistant NFGNB bacteremia (46.7% vs 46%, p = 0.949). CONCLUSION: The mortality rate of E. meningoseptica bacteremia was as high as other carbapenem-resistant NFGNB infections. The emerging E. meningoseptica infection calls for active surveillance and continued awareness from clinical physicians for this serious carbapenem-resistant infection.

Impact of removing sinks from an intensive care unit on isolations by gram-negative non-fermenting bacilli in patients with invasive mechanical ventilation. / Impacto de la retirada de los lavabos en una unidad de cuidados intensivos sobre los aislamientos por bacilos gramnegativos no fermentadores en pacientes con ventilación mecánica invasiva.

INTRODUCTION AND OBJECTIVE: Contamination of sinks, even due to their underuse, is associated with the transmission of non-fermenting gram-negative bacilli (NFGNB) to patients in Augmented Care Units. After previous monitoring with environmental and patient samples, we now explore the impact of removing sinks from ICU cubicles on incidental isolations related to health care in bronchoaspirate samples of patients with invasive mechanical ventilation (IMV). MATERIAL AND METHODS: Quasi-experimental study, before-and-after, pre-intervention annuities April 2014-2016 and post-intervention April 2016-2017. Incidence densities per 1,000 days of IMV were studied, comparing by the exact method based on the binomial distribution and estimating the incidence density ratio. RESULTS: The incidence densities per 1,000 days of IMV of isolations by NFGNB in bronchoaspirate samples of the pre and post-intervention periods were 11.28 and 1.9, respectively. This implies a post-intervention incidence density 5.90 times lower than before (95% CI: 1.49-51.05, P=.003). CONCLUSIONS: Despite of the limitations of the design, the removal of sinks showed a reduction of the isolations.

Under-utilization of taps in intensive care unit as a cause of reservoirs of nonfermenting gram-negative bacilli. / La infrautilización de grifos en una unidad de cuidados intensivos como causa de reservorios de bacilos gramnegativos no fermentadores.

INTRODUCTION: The under-utilisation of taps is associated with the generation of reservoirs of non-fermenting gram-negative bacilli with the ability to disseminate. We describe the detection and approach of the problem in an ICU. METHODS: Observational descriptive study in an ICU with individual cubicles with their own sink. We collected clinical samples from patients and environmental samples from tap aerators and reviewed the unit's hygiene measures. RESULTS: We detected four cases due to Chryseobacterium indologenes, one to Elizabethkingia meningoseptica and another to Pseudomonas aeruginosa; they were identified both in clinical and the environmental samples. The healthcare professionals reported that almost every hand hygiene opportunity was performed with a hydroalcoholic solution. After considered the daily flushing of water outlets as inefficient, it was decided to remove them. CONCLUSIONS: National recommendations were insufficient for preventing, detecting and controlling tap contamination in units with a high risk of infection. The management of taps in these units needs to be improved.

Bacilos gramnegativos no fermentadores en agua embotellada: susceptibilidad antimicrobiana y formación de biopelículas / Non fermenting Gram negative bacilli in bottled water: antimicrobial susceptibility and biofilms formation

El agua puede ser un vehículo para agentes patógenos y oportunistas portadores de multiresistencia y con capacidad de formar biopelículas (CFB). Se evaluó la presencia de indicadores microbiológicos y bacilos gramnegativos no fermentadores (BGNNF) en agua potable envasada y se estudió la susceptibilidad antimicrobiana y la CFB de los mismos. Se seleccionaron al azar 50 muestras de 250 mL obtenidos de envases de agua potable (20 L), provenientes de igual número de hogares. A cada muestra le fue realizado recuento de heterótrofos aerobios (vertido en placa), coliformes totales y termotolerantes (filtración por membrana), CFB (microplaca) y susceptibilidad antimicrobiana (Kirby-Bauer). El 92% y el 84% de las muestras presentaron coliformes totales y termotolerantes respectivamente, valores por encima de lo establecido en la Gaceta Oficial Venezolana N.° 36.395, mientras que el 86% presentó heterótrofos aerobios con cuentas >100 UFC/mL. El mayor porcentaje de BGNNF aislados pertenecía al complejo Acinetobacter baumannii/calcoaceticus (29,3%), seguido de Pseudomonas aeruginosa (17,4%), con moderada capacidad de formar biopelículas. No hubo asociación significativa entre la resistencia antimicrobiana y la CFB (p>0,05). Un porcentaje elevado de las muestras, no se ajustó a los parámetros microbiológicos establecidos en Gaceta, por lo que no se garantiza la inocuidad de las mismas.

Water can be a vehicle for multiresistant carrier pathogenic and opportunist agents with biofilm forming capacity (BFC). The presence of microbiological indicators and non fermenting Gram negative bacilli (NFGNB) was evaluated in bottled drinking water, as well as their antimicrobial susceptibility and BFC. Fifty 250 mL drinking water samples were randomly selected from 20 L drinking water bottles from the same number of homes. Each sample was tested for aerobic heterothrophics (discharged in a plate) counts, total and thermo tolerant coliforms (membrane filtration), BFC (microplate) and antimicrobial susceptibility (Kirby-Bauer). The results showed that 92% and 84% of the samples carried total and thermo tolerant coliforms respectively, values above those established in the Venezuelan Official Gazette N.o 36,395, while 86% presented aerobic heterothrophics with counts >100 CFU/mL. The highest percentage of isolated NFGNBs belonged to the Acinetobacter baumannii/calcoaceticus complex (29.3%), followed by Pseudomonas aeruginosa (17.4%) which has a moderate biofilm formation capacity. There was no significant association between antimicrobial resistance and the BFC (p>0.05). A high percentage of the samples were not adjusted to the biological parameters established in the Official Government Gazette; therefore, it is not possible to guarantee their safety.

Prevalência de bacilos Gram-negativos não fermentadores de pacientes internados em Porto Alegre-RS / Prevalence of non-fermenting Gram-negative bacilli among inpatients from Porto Alegre-RS

INTRODUÇÃO: Os bacilos Gram-negativos não fermentadores (BGNNF) são frequentemente associados às infecções hospitalares. Além da alta incidência, esses microrganismos possuem resistência a diversos antimicrobianos. OBJETIVO: Analisar a prevalência e o perfil de resistência de BGNNF. MÉTODOS: Foram analisados 14.971 laudos de pacientes em um hospital privado de Porto Alegre-RS, no período de maio de 2006 a março de 2008, sem distinção de sexo e idade. RESULTADOS E CONCLUSÃO: Foram isoladas 326 amostras de BGNNF. As espécies mais prevalentes foram: Pseudomonas aeruginosa (65,03 por cento), Acinetobacter baumannii (16,56 por cento) e Stenotrophomonas maltophilia (9,5 por cento). Outras espécies apresentaram índices inferiores a 5 por cento. Os microrganismos foram isolados de diversos sítios infecciosos. Os materiais biológicos que apresentaram maior positividade para esses microrganismos foram o aspirado traqueal (38,34 por cento), o escarro (18,71 por cento) e a urina (15,95 por cento). A resistência bacteriana mostrou-se mais expressiva a tetraciclinas (89,57 por cento) e sulfametoxazol/trimetoprima (79,75 por cento). Os antimicrobianos mais ativos foram polimixina B, com 100 por cento de sensibilidade, e piperaciclina/tazobactam, com 75,2 por cento de sensibilidade.

INTRODUCTION: The non-fermenting Gram-negative bacilli (NFGNB) have been widely associated with nosocomial infections. Not only are these microorganisms highly prevalent but they are also highly resistant to NFGNB. OBJECTIVE: To assess the prevalence and resistance profile of non-fermenting Gram-negative bacilli. METHODS: 14.971 patient reports from a private hospital in Porto Alegre, Rio Grande do Sul, from May/2006 to March/2008 were analyzed. RESULTS AND CONCLUSION: Three hundred twenty-six samples of non-fermenting Gram-negative bacilli were isolated. The most prevalent species were Pseudomonas aeruginosa (65.03 percent), Acinetobacter baumannii (16.56 percent), and Stenotrophomonas maltophilia (9.5 percent). Other species showed rates lower than 5 percent. The microorganisms were isolated from several infectious sites and the biological materials that showed higher positivity were the following: tracheal aspirate (38.34 percent), spittle (18.71 percent) and urine (15.95 percent). Bacterial resistance was higher with tetracyclines (89.57 percent) and sulfamethoxazole/trimethoprim (79.75 percent). The most active antimicrobials were polymyxin B and piperacillin/tazobactam with 100 percent and 75.2 percent sensibility, respectively.

Criterios de ensayo, interpretación e informe de las pruebas de sensibilidad a los antibióticos en los bacilos gram negativos no fermentadores de importancia clínica: recomendaciones de la Subcomisión de Antimicrobianos de la Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas, Asociación Argentina de Microbiología / Antimicrobial susceptibility testing in clinically relevant non-fermenting gram-negative bacilli: recommendations from the Antimicrobial Agents Subcommittee of the Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas, Asociación Argentina de Microbiología

En este documento se dan a conocer una serie de recomendaciones para el ensayo, la lectura, la interpretación y el informe de las pruebas de sensibilidad a los antimicrobianos para los bacilos gram negativos no fermentadores (BGNNF) que se aíslan en humanos. Se adoptaron como base las recomendaciones internacionales, las de la Subcomisión de Antimicrobianos de la Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas y las de un grupo de expertos invitados. Se incluye, además, la nomenclatura actualizada de los BGNNF y la descripción de algunas de sus características individuales, de sus resistencias naturales o habituales a los antimicrobianos de uso clínico y de los mecanismos responsables de tales resistencias. También se indican los agentes antimicrobianos que se deberían ensayar frente a las distintas especies, con la especificación de cuáles deberían ser informados, y su ubicación estratégica en las placas de cultivo para poder detectar los mecanismos de resistencia más frecuentes y relevantes. Por último, se detallan los métodos de detección y de confirmación fenotípica de la presencia de b-lactamasas emergentes en Argentina, como las carbapenemasas clases A y B.

This document contains the recommendations for antimicrobial susceptibility testing of the clinically relevant non-fermenting gram-negative bacilli (NFGNB), adopted after conforming those from international committees to the experience of the Antimicrobial Agents Subcommittee members and invited experts. This document includes an update on NFGNB classification and description, as well as some specific descriptions regarding natural or frequent antimicrobial resistance and a brief account of associated resistance mechanisms. These recommendations not only suggest the antimicrobial drugs to be evaluated in each case, but also provide an optimization of the disk diffusion layout and a selection of results to be reported. Finally, this document also includes a summary of the different methodological approaches that may be used for detection and confirmation of emerging b-lactamases, such as class A and B carbapenemases.