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A 7-year national survey on bacterial resistance in bronchoalveolar lavage from patients hospitalized in Argentina
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Diagnostic Microbiology and Infectious Disease 60 (2008) 65 – 69 www.elsevier.com/locate/diagmicrobio
Antimicrobial Susceptibility Studies
A 7-year national survey on bacterial resistance in bronchoalveolar lavage from patients hospitalized in Argentina☆ Carlos Bantar a,⁎, Angela Famiglietti a , Marcela Radice a , Mirta Quinteros a , for The Antimicrobial Committee a,1 , The SIR Participants Group b,2 a
Sociedad Argentina de Bacteriología, Asociación Argentina de Microbiología, Buenos Aires, Argentina b Thirty-six centers across Argentina Received 21 May 2007; accepted 7 July 2007
Abstract The purpose of this study is to undertake a nationwide survey on bacterial resistance in bronchoalveolar lavage (BAL) from patients hospitalized in Argentina. A 2-month point prevalence study was conducted twice yearly (April–May and October–November) from 1997 to 2003 by 36 Argentinean centers. Antimicrobial susceptibility data of the potential pathogens recovered from the BAL (samples containing b1% of squamous epithelial cells and bacterial counts ≥104 CFU/mL) of inpatients (i.e., ≥48-h hospital length of stay) with suspected hospital-acquired pneumonia (HAP) were collected on a computerized system (SIR) described previously. The survey was split into 2 periods for comparison purposes, 1997 to 2000 and 2001 to 2003. A total of 752 organisms were included. Staphylococcus aureus was the most frequent species, followed by Acinetobacter spp. and Pseudomonas aeruginosa. In both periods, more than a half of the Klebsiella pneumoniae strains displayed a phenotype of extended-spectrum β-lactamase producer. A doubling of imipenem-resistant Acinetobacter frequency was shown from the 1st period to the 2nd one (25–48%). More than two-thirds of the S. aureus strains proved to be methicillin resistant in both periods, and a pronounced decrease of resistance rates to trimethoprim/sulfamethoxazole and rifampin was shown in the 2nd period. The present study shows the worrisome increasing bacterial resistance in BAL samples to most available antimicrobial options for treating patients with suspected HAP. Variations over time support the need for systematic tailored surveillance and compel us to establish a rational usage of antimicrobial agents in our country. © 2008 Elsevier Inc. All rights reserved. Keywords: Antimicrobial resistance; Nosocomial pneumonia; Bronchoalveolar lavage
☆ CB has received a fee for speaking from Wyeth and Laboratorios Bago and a fee for serving as a member of the Latin America Advisory Board of Wyeth. MR, AF, and MQ have no competing interest to declare. ⁎ Corresponding author. 3100 Paraná, Entre Ríos. Fax: +54-343-4310783. E-mail address: [email protected] (C. Bantar). 1 The Antimicrobial Committee: C. Bantar, J.M. Casellas, E. Couto, A. Famiglietti, M. Galas, G. Gutkind, J. Kovensky, M. Marín, F. Nicola, F. Pasterán, M. Quinteros, M. Radice, and R. Soloaga. 2 The SIR Participant Group: M. Almuzara (H. Eva Perón, Buenos Aires), M. Altschuler (H. Sor Maria Ludovica, La Plata), M. Arias (H. San Bernardo, Salta), L. Bardi (Clínica Modelo, Morón), L. Carvajal (H. de Niños, Córdoba), J.M. Casellas (Sanatorio San Lucas, San Fernando), N. Castagnaviz (H. Escuela Eva Perón, Rosario), H. Castro (H. Marcial Quiroga, San Juan), M. Defendi (H. Iturraspe, Santa Fé), D. Durany (H. Lopez Lima, Río Negro), A. Famiglietti (H. de Clínicas, Buenos Aires), A. Fernández (Fundación Favaloro, Buenos Aires), R. Fernández (H. San Roque, Paraná), L. Fernández Canigia (H. Alemán, Buenos Aires), C. Latorraga (Sanatorio Greyton, Buenos Aires), M. Machaín (H. Piñeyro, Junín), A. Monterisi (H. Nacional de Clínicas, Córdoba), N. Moreno (H. Gdor, Centeno, General Pico), R. Navarro (Lab. Central de Análisis, San Juan), F. Pantozzi (H. Italiano, La Plata), A. Pariz de Baeza (H. Privado del Sur, Bahía Blanca), S. Perez (Lab. IACA, Bahía Blanca), L. Pianciola (H. Heller, Neuquén), Piñeiro(H. Gutierrez, Venado Tuerto), G. Posse (Sanatorio Adventista, Libertador San Martín), M. Quinteros (H. Muñiz, Buenos Aires), M. Rodrigo (Sanatorio Stoiz, Avellaneda), G. Rubinstein (H. Carrillo, Bariloche), V. Scilingo (CEI, Buenos Aires), M. Schuster (Clínica Pergamino, Pergamino), J. Smayevsky (CEMIC, Buenos Aires), S. Soriano (Policlínico Neuquén, Cipoletti), N. Suoni (H. del Sur Mendocino, San Rafael), E. Sutich (H. Centenario, Rosario), D. Tanaro (H. Centenario, Gualeguaychú), and M. Vergara (Sanatorio Nosiglia, Posadas).
0732-8893/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.diagmicrobio.2007.07.005
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1. Introduction Hospital-acquired pneumonia (HAP) remains a major cause of morbidity and mortality despite advances in antimicrobial therapy and infection control practices (American Thoracic Society, 2002). Indeed, ventilator-associated pneumonia (VAP) affects roughly 10% to 30% of patients receiving mechanical ventilation, with mortality rates reaching up to 70% when lung infection is caused by high-risk pathogens (Chastre and Fagon, 1996). Published evidences from almost 20 years ago to date concur in that the appropriate initial empiric treatment may influence the mortality rate of patients with VAP (Torres et al., 1990; Luna et al., 1997; Kollef et al., 2006). In some studies, the “appropriate antimicrobial therapy” refers to the administration of antibiotics according to the recommendations and guidelines of scientific societies, in conjunction with pharmacologic and microbiologic considerations (Torres et al., 1990). However, most authors (Luna et al., 1997; Kollef et al., 2006) have restricted the definition of adequate antibiotic therapy to sensitivity patterns from in vitro tests, instead of relating it to the clinical response to therapy, thus, focusing only on microbiologically documented infections. Furthermore, getting microbiologic data from bronchoalveolar lavage (BAL) seems to improve the clinical outcome of patients with HAP and to decrease unnecessary antibiotic consumption (Fagon et al., 2000). These cumulative evidences compel us to know the local susceptibility pattern of pathogens, as they give the basis for the rational selection of the initial antimicrobial therapy in patients with HAP. We report herein a 7-year national survey on bacterial resistance in BAL from patients hospitalized in 36 Argentinean centers.
Organisms were identified according to the standard procedures (Murray et al., 1995). Susceptibility testing was carried out by the disk diffusion method following the Clinical and Laboratory Standards Institute (formerly known as National Committee for Clinical Laboratory Standards [NCCLS]) recommendations (NCCLS, 2003). Ampicillin/ sulbactam, piperacillin/tazobactam, ceftazidime, cefotaxime, cefepime, imipenem, amikacin, and ciprofloxacin were tested against Gram-negative rods. Presumptive presence of extended-spectrum β-lactamase (ESBL) was routinely screened by the double-disk synergy test with clavulanic acid and cefotaxime/ceftriaxone and ceftazidime (Jarlier et al., 1988). Oxacillin, vancomycin, gentamicin, ciprofloxacin, rifampin, trimethoprim/sulfamethoxazole, and minocycline were assayed against Staphylococcus aureus. S. aureus ATCC 25923, Escherichia coli, ATCC 35218 and ATCC
2. Materials and methods A 2-month point prevalence study was conducted twice yearly (April–May and October–November) from 1997 to 2003 by 36 Argentinean centers (100–500 beds), representing 48% of the Argentinean provinces (Fig. 1). Antimicrobial susceptibility data of the potential pathogens recovered from BAL (samples containing b1% of squamous epithelial cells and bacterial counts ≥104 CFU/mL) of inpatients with suspected pneumonia were collected on a computerized system (SIR) described previously (Bantar et al., 2000). Suspected nosocomial pneumonia was defined as a new infiltrate on chest X-ray 72 h or more after admission with 2 or more of the following symptoms: fever ≥38 °C, new onset of production of purulent sputum, significant increase in volume of purulent sputum, or peripheral leukocyte count N1010/L (Garner et al., 1988). For calculation of resistance rates, the SIR system automatically eliminates multiple strains from the same patient if they display identical susceptibility pattern and if they are recovered within a 6-month period.
Fig. 1. State distribution (open circle) of 36 centers participating in a national survey across the Argentine Republic.
C. Bantar et al. / Diagnostic Microbiology and Infectious Disease 60 (2008) 65–69
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Table 1 Species distribution in BAL from patients hospitalized in Argentina from 1997 to 2003 with suspected HAP
Table 3 Resistance profile of S. aureus recovered from the BAL of patients hospitalized in Argentina from 1997 to 2003 with suspected HAP
Organism a
Frequency (%), n = 752
Antibiotic
S. aureus Acinetobacter spp. P. aeruginosa K. pneumoniae Streptococcus pneumoniae Haemophilus influenzae Proteus mirabilis Enterobacter spp. Serratia spp. Others
197 (26.2) 184 (24.5) 156 (20.7) 55 (7.3) 26 (3.5) 26 (3.5) 25 (3.3) 23 (3.1) 11 (1.5) 49 (6.4)
Oxacillin Vancomycin Gentamicin Ciprofloxacin Rifampin Trimethoprim/ sulfamethoxazole Minocycline
a
Others include Citrobacter and Providencia species, Klebsiella oxytoca, Proteus vulgaris, Morganella morganii, Stenotrophomonas maltophilia, and Burkholderia cepacia.
25922, Enterococcus faecalis ATCC 29212, and Pseudomonas aeruginosa ATCC 27853 were used as the controls. Resistance rates were analyzed by comparison of proportions with the χ2 or Fisher's exact tests using the Epi Info statistical package. A P value of ≤0.05 was regarded as significant. 3. Results A total of 752 organisms were included. All centers collected a similar number of isolates (mean, 21 strains per center during the whole study). The species distribution is given in Table 1. S. aureus was the most frequent species, followed by Acinetobacter spp. and P. aeruginosa. These 3 pathogens represented roughly 75% of the total. To assess variations over time, we split the survey into 2 periods for comparison purposes, 1997 to 2000 and 2001 to 2003. No change in prevalence of the different organisms was observed between the 2 periods. Resistance profiles for the most frequent Gram-negative rods are given in Table 2. Overall, high resistance rates were displayed by all species against the antimicrobial options
Resistance (%) at the following periods 1997–2000 (n = 105)
2001–2003 (n = 92)
72.3 0 70.5 66.7 38.1 40.9
67.4 0 67.4 64.1 6.5 8.7
0.9
1.1
Comparative analysis between 2 periods. Numbers in boldface indicate statistically significant difference between periods (P b 0.001).
currently selected as the initial empiric treatment of HAP, with the exception of imipenem against Klebsiella pneumoniae. A doubling of imipenem-resistant Acinetobacter frequency was shown from 1997 to 2003. Remaining resistance rates were similar in both periods. Data for S. aureus are given in Table 3. More than two-thirds of the strains proved to be methicillin-resistant S. aureus (MRSA) in both periods and appeared to be associated with gentamicin resistance. A pronounced decrease of resistance rates to trimethoprim/sulfamethoxazole and rifampin was shown in the 2nd period (2001–2003). Minocycline proved highly active against this pathogen in both periods. 4. Discussion Both the impact of the increasing bacterial resistance on the patient care and the importance of getting local microbiologic data for the management of patients with HAP have recently been reviewed (Koulenty and Rello, 2006; Diaz et al., 2007). However, few microbiologic surveillance studies have focused specifically on patients with HAP, and none of them have reported data limited only to BAL specimens with significant colony counts from patients with suspected HAP (Mathai et al., 2001; Gales
Table 2 Resistance profiles of the most frequent Gram-negative roads recovered from BAL of patients hospitalized in Argentina from 1997 to 2003 with suspected HAP Antibiotic
Resistance (%) at the following periods Acinetobacter spp
P. aeruginosa
K. pneumoniae
1997–2000 (n = 89) 2001–2003 (n = 95) 1997–2000 (n = 77) 2001–2003 (n = 79) 1997–2000 (n = 33) 2001–2003 (n = 23) Ampicillin/sulbactam Ceftazidime Cefepime Piperacillin/ tazobactam Imipenem Amikacin Ciprofloxacin
70.8 94.3 83.1 93.2
71.6 92.6 80.7 92.6
NA 24.7 23.4 39.0
NA 25.3 25.3 38.0
72.7 51.5 36.4 33.3
73.9 56.5 47.8 26.0
24.7 87.6 88.8
48.4 76.8 91.6
31.6 32.5 46.7
23.4 33.0 53.2
0 36.4 27.3
0 26.0 30.4
Comparative analysis between 2 periods. Numbers in boldface indicate the only statistically significant difference between periods (P b 0.001). Ceftazidime resistance in K. pneumoniae represents all strains with phenotype of ESBL producer. It should be noted that ampicillin/sulbactam results against Acinetobacter cannot be extrapolated to sulbactam MIC because, solely, sulbactam is the active compound. NA = not assayed.
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et al., 2002), as our study did. To our knowledge, the present study is the 1st nationwide surveillance approaching this issue. We consider that this is a major fact, as the likelihood of including colonizer organisms might be minimized by restricting the analysis solely to microbiologically significant organism from BAL specimens of patients with suspected HAP. Nevertheless, the frequency of S. aureus, P. aeruginosa, and K. pneumoniae we found was similar to that reported by the SENTRY Program in North America and Latin America (Mathai et al., 2001; Gales et al., 2002), as well as to that collected from 1689 episodes of VAP documented by bronchoscopic techniques in 24 studies performed in the United States and Europe (Chastre and Fagon, 2002). By contrast, we have observed a higher frequency of Acinetobacter spp. (24.5% in our study versus 2.8%, 9.6% and 7.9% reported by the SENTRY program in North America, in Latin America, and in the VAP episodes of USA–Europe, respectively). Although the SENTRY studies included hospitalized patients without distinction between community-acquired pneumonia and HAP (Mathai et al., 2001; Gales et al., 2002), the difference seems to be too wide to be attributable only to this situation. In addition, the frequency is also much higher than that described for the patients with VAP in the United States and Europe (Chastre and Fagon, 2002). In the present study, Acinetobacter displayed high rate of bacterial resistance to most antibiotics. The frequency of imipenem resistance (25%) shown in the period 1997 to 2000 is higher than that described by the SENTRY for Latin America along the same period (15%) (Gales et al., 2002). In fact, this rate for Latin America as a whole in the SENTRY study might have been influenced by the 2 Argentinean centers participating in this program, as both of them are from the same area and displayed an imipenem resistance frequency by Acinetobacter of 40% in a tailored study reported by the SENTRY (Tognim et al., 2000). It is noteworthy that the imipenem resistance rate we found in the period 1997 to 2000 is also higher than that reported by ourselves in Argentina in a previous period (9% between 1996 and 1998) (Bantar et al., 2000), and it was doubled in the period 2001 to 2003. Therefore, these findings suggest that a sustainable increase in imipenem resistance by Acinetobacter spp. is occurring in Argentina since 1996. Indeed, this resistance was reported early in our country (Brown et al., 1998), and its mechanism and spread is currently under discussion (Brown et al., 2005; Merkier and Centron, 2006). Four different clusters (A, B, C, and E) of imipenem-resistant Acinetobacter expressing the ARI-2 enzyme (currently named OXA-51) were described in 3 Argentinean centers between 1994 and 1998, suggesting transferable spread of imipenem resistance in Argentina (Brown et al., 2005). The frequency of K. pneumoniae strains with phenotype of ESBL producer is much higher in our study (more than 50%) than that reported by the SENTRY in the United States (5%) and in Latin America (29%) (Mathai et al., 2001; Gales et al., 2002). The presence of ESBL in our country was 1st
reported by Casellas and Goldberg (1989). Two indigenous novel ESBLs were described in Argentina, CTX-M-2 (Bauernfeind et al., 1992) and PER-2 (Bauernfeind et al., 1996). Early epidemiologic studies performed by Galas et al. (1998) and Galas et al. (1999) demonstrated that CTX-M-2 (64–70%) and, to a lesser degree, SHV-1 derivates (i.e., SHV-2 and SHV-5, 11–20%) and PER-2 (5–10%) were the most prevalent ESBLs among a number of Argentinean K. pneumoniae and E. coli strains, a more recent study that this situation remains unchanged (Quinteros et al., 2003). MRSA was highly prevalent in our study. In 1999, Corso et al. (1999) reported a clonal typing study among 148 isolates of methicillin-resistant S. aureus collected by 13 hospitals from Argentina. These authors stated that the prevalent clone (62% of the isolates) had a pulsed-field gel electrophoresis pattern similar to that of the Brazilian isolates, that is, the clone XI∷B∷B. This clone was also resistant to gentamicin, macrolides, rifampin, tetracycline, trimethoprim/sulfamethoxazole, and ciprofloxacin. This multiresistant phenotype was shown in the 1st period of the present study (1997–2000). Interestingly, most MRSA strains recovered from the BAL in the 2nd period, 2001 to 2003, proved susceptibility to trimethoprim/sulfamethoxazole and rifampin. In 2002, a novel MRSA clone carrying the SCCmec type I element with this susceptibility pattern was characterized in Córdoba, Argentina (Sola et al., 2002; Sola et al., 2006), and the replacement of the previous resistant clone by this more susceptible one was subsequently reported (Gardella et al., 2005). These findings might explain our results with the BAL samples. The present study shows the worrisome increasing bacterial resistance in BAL samples to most available antimicrobial options for treating patients with suspected HAP. Variations over time support the need for a systematic tailored surveillance and compel us to establish a rational usage of antimicrobial agents in our country.
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C. Bantar et al. / Diagnostic Microbiology and Infectious Disease 60 (2008) 65–69 Brown S, Young H-K, Amyes S (2005) Characterisation of OXA-51, a novel class D carbapenemase found in genetically unrelated clinical strains of Acinetobacter baumannii from Argentina. Clin Microbiol Infect 11:15–23. Casellas JM, Goldberg M (1989) Incidence of strains producing extended spectrum beta-lactamases in Argentina. Infection 17:434–436. Chastre J, Fagon J-V (1996) Ventilator-associated pneumonia. Am J Respir Crit Care Med 154:116–123. Chastre J, Fagon J-V (2002) Ventilator-associated pneumonia. Am J Respir Crit Care Med 165:867–903. Corso A, Santos Sanches I, Aires de Sousa M, Rossi A, de Lencastre H (1999) Spread of a methicillin-resistant and multiresistant epidemic clone of Staphylococcus aureus in Argentina. Microb Drug Reist 4:277–288. Diaz E, Muñoz E, Agbaht K, Rello J (2007) Management of ventilatorassociated pneumonia caused by multiresistant bacteria. Curr Opin Crit Care 13:45–50. Fagon JY, Chastre J, Wolff M, Gervais C, Parer-Aubas S, Stéphan F, Similowski T, Mercat A, Diehl JL, Sollet JP, Tenaillon A (2000) Invasive and noninvasive strategies for management of suspected ventilatorassociated pneumonia: a randomized trial. Ann Intern Med 132:621–630. Galas M, Pasterán F, Melano R, et al (1998) Unusual distribution of enzymatic resistance to third-generation cephalosporin (TGC) in E. coli in Argentina [abstract 109]. Programs and Abstracts of the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC). September 24–27, San Diego, CA, USA. Washington D.C.: American Society for Microbiology, p 201. Galas M, Rapoport M, Pasterán F, et al (1999) High distribution of CTXM-2 β-lactamase among Klebsiella spp. isolates in an Argentinean extended spectrum β-lactamase (ESBLA) surveillance program. [abstract 1474] Programs and Abstracts of the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC). September 26–29, San Francisco, CA, USA. Washington D.C.: American Society for Microbiology, p 165. Gales AC, Sader HS, Jones RN (2002) 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). Diagn Microbiol Infect Dis 44:301–311. Gardella N, Picasso R, Predari SC, Lasala M, Foccoli M, Benchetrit G, Famiglietti A, Catalano M, Mollerach M, Gutkind G (2005) Methicillinresistant Staphylococcus aureus strains in Buenos Aires teaching hospitals: replacement of the multidrug resistant South American clone by another susceptible to rifampin, minocycline and trimethoprim– sulfamethoxazole. Rev Argent Microbiol 37:156–160. Garner JS, Jarvis WR, Emori TG, Horan TC, Hughes JM (1988) CDC definitions for nosocomial infections. Am J Infect Control 16:128–140. Jarlier V, Nicolas M, Fournier G, Philippon A (1988) Extended broadspectrum beta lactamases conferring transferable resistance to
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newer beta lactam agents in Enterobacteriaceae. Rev Infect Dis 10: 867–878. Kollef MH, Morrow LE, Niederman MS, Leeper KV, Anzueto A, BenzScott L, Rodino FJ (2006) Clinical characteristics and treatment patterns among patients with ventilator-associated pneumonia. Chest 129: 1210–1218. Koulenty D, Rello J (2006) Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care. Expert Opin Pharmacother 7:1555–1569. Luna CM, Vujacich P, Niederman MS, Vay C, Gherardi C, Matera J, Jolly EC (1997) Impact of BAL data on the therapy and outcome of ventilatorassociated pneumonia. Chest 111:676–687. Mathai D, Lewis MT, Kugler KC, Pfaller MA, Jones RN (2001) Antibacterial activity of 41 antimicrobials tested against over 2773 bacterial isolates from hospitalized patients with pneumonia: results from the SENTRY Antimicrobial Surveillance Program (North America, 1998). Diagn Microbiol Infect Dis 39:105–116. Merkier AK, Centron D (2006) bla (OXA-51)-type beta-lactamase genes are ubiquitous and vary within a strain in Acinetobacter baumannii. Int J Antimicrob Agents 28:110–113. Murray P, Baron E, Pfaller M, Tenover F, Yolken R, Eds, (1995 ) In Manual of Clinical Microbiology. (6th ed). Washington D.C.: American Society for Microbiology, pp 262–560. National Committee for Clinical Laboratory Standards (2003) Performance Standards for Antimicrobial Susceptibility Testing: NCCLS Document M100-S13. Wayne, PA: NCCLS. Quinteros M, Radice M, Gardella N, Rodriguez MM, Costa N, Korbenfeld D, Couto E, Gutkind G, Microbiology Study Group (2003) Extendedspectrum beta-lactamases in Enterobacteriaceae in Buenos Aires, Argentina, public hospitals. Antimicrob Agents Chemother 47: 2864–2867. Sola C, Gribaudo G, Vindel A, Patrito L, Bocco JL, Córdoba MRSA Collaborative Study Group (2002) Identification of a novel methicillinresistant Staphylococcus aureus epidemic clone in Córdoba, Argentina, Involved in Nosocomial Infections. J Clin Microbiol 40:1427–1435. Sola C, Cortes P, Saca HA, Vindel A, Bocco JL, Córdoba MRSA Collaborative Study Group (2006) Evolution and molecular characterization of methicillin-resistant Staphylococcus aureus epidemic and sporadic clones in Cordoba, Argentina. J Clin Microbiol 44:192–200. Tognim MC, Andrade SS, Silbert S, Gales AC, Jones RN, Sader HS (2000) 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. Int J Infect Dis 8:284–291. Torres A, Aznar R, Gatell JM, Jiménez P, González J, Ferrer A, Celis R, Rodriguez-Roisin R (1990) Incidence, risk, and prognosis factors of nosocomial pneumonia in mechanically ventilated patients. Am Rev Respir Dis 142:523–528.
Diagnostic Microbiology and Infectious Disease 60 (2008) 65 – 69 www.elsevier.com/locate/diagmicrobio
Antimicrobial Susceptibility Studies
A 7-year national survey on bacterial resistance in bronchoalveolar lavage from patients hospitalized in Argentina☆ Carlos Bantar a,⁎, Angela Famiglietti a , Marcela Radice a , Mirta Quinteros a , for The Antimicrobial Committee a,1 , The SIR Participants Group b,2 a
Sociedad Argentina de Bacteriología, Asociación Argentina de Microbiología, Buenos Aires, Argentina b Thirty-six centers across Argentina Received 21 May 2007; accepted 7 July 2007
Abstract The purpose of this study is to undertake a nationwide survey on bacterial resistance in bronchoalveolar lavage (BAL) from patients hospitalized in Argentina. A 2-month point prevalence study was conducted twice yearly (April–May and October–November) from 1997 to 2003 by 36 Argentinean centers. Antimicrobial susceptibility data of the potential pathogens recovered from the BAL (samples containing b1% of squamous epithelial cells and bacterial counts ≥104 CFU/mL) of inpatients (i.e., ≥48-h hospital length of stay) with suspected hospital-acquired pneumonia (HAP) were collected on a computerized system (SIR) described previously. The survey was split into 2 periods for comparison purposes, 1997 to 2000 and 2001 to 2003. A total of 752 organisms were included. Staphylococcus aureus was the most frequent species, followed by Acinetobacter spp. and Pseudomonas aeruginosa. In both periods, more than a half of the Klebsiella pneumoniae strains displayed a phenotype of extended-spectrum β-lactamase producer. A doubling of imipenem-resistant Acinetobacter frequency was shown from the 1st period to the 2nd one (25–48%). More than two-thirds of the S. aureus strains proved to be methicillin resistant in both periods, and a pronounced decrease of resistance rates to trimethoprim/sulfamethoxazole and rifampin was shown in the 2nd period. The present study shows the worrisome increasing bacterial resistance in BAL samples to most available antimicrobial options for treating patients with suspected HAP. Variations over time support the need for systematic tailored surveillance and compel us to establish a rational usage of antimicrobial agents in our country. © 2008 Elsevier Inc. All rights reserved. Keywords: Antimicrobial resistance; Nosocomial pneumonia; Bronchoalveolar lavage
☆ CB has received a fee for speaking from Wyeth and Laboratorios Bago and a fee for serving as a member of the Latin America Advisory Board of Wyeth. MR, AF, and MQ have no competing interest to declare. ⁎ Corresponding author. 3100 Paraná, Entre Ríos. Fax: +54-343-4310783. E-mail address: [email protected] (C. Bantar). 1 The Antimicrobial Committee: C. Bantar, J.M. Casellas, E. Couto, A. Famiglietti, M. Galas, G. Gutkind, J. Kovensky, M. Marín, F. Nicola, F. Pasterán, M. Quinteros, M. Radice, and R. Soloaga. 2 The SIR Participant Group: M. Almuzara (H. Eva Perón, Buenos Aires), M. Altschuler (H. Sor Maria Ludovica, La Plata), M. Arias (H. San Bernardo, Salta), L. Bardi (Clínica Modelo, Morón), L. Carvajal (H. de Niños, Córdoba), J.M. Casellas (Sanatorio San Lucas, San Fernando), N. Castagnaviz (H. Escuela Eva Perón, Rosario), H. Castro (H. Marcial Quiroga, San Juan), M. Defendi (H. Iturraspe, Santa Fé), D. Durany (H. Lopez Lima, Río Negro), A. Famiglietti (H. de Clínicas, Buenos Aires), A. Fernández (Fundación Favaloro, Buenos Aires), R. Fernández (H. San Roque, Paraná), L. Fernández Canigia (H. Alemán, Buenos Aires), C. Latorraga (Sanatorio Greyton, Buenos Aires), M. Machaín (H. Piñeyro, Junín), A. Monterisi (H. Nacional de Clínicas, Córdoba), N. Moreno (H. Gdor, Centeno, General Pico), R. Navarro (Lab. Central de Análisis, San Juan), F. Pantozzi (H. Italiano, La Plata), A. Pariz de Baeza (H. Privado del Sur, Bahía Blanca), S. Perez (Lab. IACA, Bahía Blanca), L. Pianciola (H. Heller, Neuquén), Piñeiro(H. Gutierrez, Venado Tuerto), G. Posse (Sanatorio Adventista, Libertador San Martín), M. Quinteros (H. Muñiz, Buenos Aires), M. Rodrigo (Sanatorio Stoiz, Avellaneda), G. Rubinstein (H. Carrillo, Bariloche), V. Scilingo (CEI, Buenos Aires), M. Schuster (Clínica Pergamino, Pergamino), J. Smayevsky (CEMIC, Buenos Aires), S. Soriano (Policlínico Neuquén, Cipoletti), N. Suoni (H. del Sur Mendocino, San Rafael), E. Sutich (H. Centenario, Rosario), D. Tanaro (H. Centenario, Gualeguaychú), and M. Vergara (Sanatorio Nosiglia, Posadas).
0732-8893/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.diagmicrobio.2007.07.005
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1. Introduction Hospital-acquired pneumonia (HAP) remains a major cause of morbidity and mortality despite advances in antimicrobial therapy and infection control practices (American Thoracic Society, 2002). Indeed, ventilator-associated pneumonia (VAP) affects roughly 10% to 30% of patients receiving mechanical ventilation, with mortality rates reaching up to 70% when lung infection is caused by high-risk pathogens (Chastre and Fagon, 1996). Published evidences from almost 20 years ago to date concur in that the appropriate initial empiric treatment may influence the mortality rate of patients with VAP (Torres et al., 1990; Luna et al., 1997; Kollef et al., 2006). In some studies, the “appropriate antimicrobial therapy” refers to the administration of antibiotics according to the recommendations and guidelines of scientific societies, in conjunction with pharmacologic and microbiologic considerations (Torres et al., 1990). However, most authors (Luna et al., 1997; Kollef et al., 2006) have restricted the definition of adequate antibiotic therapy to sensitivity patterns from in vitro tests, instead of relating it to the clinical response to therapy, thus, focusing only on microbiologically documented infections. Furthermore, getting microbiologic data from bronchoalveolar lavage (BAL) seems to improve the clinical outcome of patients with HAP and to decrease unnecessary antibiotic consumption (Fagon et al., 2000). These cumulative evidences compel us to know the local susceptibility pattern of pathogens, as they give the basis for the rational selection of the initial antimicrobial therapy in patients with HAP. We report herein a 7-year national survey on bacterial resistance in BAL from patients hospitalized in 36 Argentinean centers.
Organisms were identified according to the standard procedures (Murray et al., 1995). Susceptibility testing was carried out by the disk diffusion method following the Clinical and Laboratory Standards Institute (formerly known as National Committee for Clinical Laboratory Standards [NCCLS]) recommendations (NCCLS, 2003). Ampicillin/ sulbactam, piperacillin/tazobactam, ceftazidime, cefotaxime, cefepime, imipenem, amikacin, and ciprofloxacin were tested against Gram-negative rods. Presumptive presence of extended-spectrum β-lactamase (ESBL) was routinely screened by the double-disk synergy test with clavulanic acid and cefotaxime/ceftriaxone and ceftazidime (Jarlier et al., 1988). Oxacillin, vancomycin, gentamicin, ciprofloxacin, rifampin, trimethoprim/sulfamethoxazole, and minocycline were assayed against Staphylococcus aureus. S. aureus ATCC 25923, Escherichia coli, ATCC 35218 and ATCC
2. Materials and methods A 2-month point prevalence study was conducted twice yearly (April–May and October–November) from 1997 to 2003 by 36 Argentinean centers (100–500 beds), representing 48% of the Argentinean provinces (Fig. 1). Antimicrobial susceptibility data of the potential pathogens recovered from BAL (samples containing b1% of squamous epithelial cells and bacterial counts ≥104 CFU/mL) of inpatients with suspected pneumonia were collected on a computerized system (SIR) described previously (Bantar et al., 2000). Suspected nosocomial pneumonia was defined as a new infiltrate on chest X-ray 72 h or more after admission with 2 or more of the following symptoms: fever ≥38 °C, new onset of production of purulent sputum, significant increase in volume of purulent sputum, or peripheral leukocyte count N1010/L (Garner et al., 1988). For calculation of resistance rates, the SIR system automatically eliminates multiple strains from the same patient if they display identical susceptibility pattern and if they are recovered within a 6-month period.
Fig. 1. State distribution (open circle) of 36 centers participating in a national survey across the Argentine Republic.
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Table 1 Species distribution in BAL from patients hospitalized in Argentina from 1997 to 2003 with suspected HAP
Table 3 Resistance profile of S. aureus recovered from the BAL of patients hospitalized in Argentina from 1997 to 2003 with suspected HAP
Organism a
Frequency (%), n = 752
Antibiotic
S. aureus Acinetobacter spp. P. aeruginosa K. pneumoniae Streptococcus pneumoniae Haemophilus influenzae Proteus mirabilis Enterobacter spp. Serratia spp. Others
197 (26.2) 184 (24.5) 156 (20.7) 55 (7.3) 26 (3.5) 26 (3.5) 25 (3.3) 23 (3.1) 11 (1.5) 49 (6.4)
Oxacillin Vancomycin Gentamicin Ciprofloxacin Rifampin Trimethoprim/ sulfamethoxazole Minocycline
a
Others include Citrobacter and Providencia species, Klebsiella oxytoca, Proteus vulgaris, Morganella morganii, Stenotrophomonas maltophilia, and Burkholderia cepacia.
25922, Enterococcus faecalis ATCC 29212, and Pseudomonas aeruginosa ATCC 27853 were used as the controls. Resistance rates were analyzed by comparison of proportions with the χ2 or Fisher's exact tests using the Epi Info statistical package. A P value of ≤0.05 was regarded as significant. 3. Results A total of 752 organisms were included. All centers collected a similar number of isolates (mean, 21 strains per center during the whole study). The species distribution is given in Table 1. S. aureus was the most frequent species, followed by Acinetobacter spp. and P. aeruginosa. These 3 pathogens represented roughly 75% of the total. To assess variations over time, we split the survey into 2 periods for comparison purposes, 1997 to 2000 and 2001 to 2003. No change in prevalence of the different organisms was observed between the 2 periods. Resistance profiles for the most frequent Gram-negative rods are given in Table 2. Overall, high resistance rates were displayed by all species against the antimicrobial options
Resistance (%) at the following periods 1997–2000 (n = 105)
2001–2003 (n = 92)
72.3 0 70.5 66.7 38.1 40.9
67.4 0 67.4 64.1 6.5 8.7
0.9
1.1
Comparative analysis between 2 periods. Numbers in boldface indicate statistically significant difference between periods (P b 0.001).
currently selected as the initial empiric treatment of HAP, with the exception of imipenem against Klebsiella pneumoniae. A doubling of imipenem-resistant Acinetobacter frequency was shown from 1997 to 2003. Remaining resistance rates were similar in both periods. Data for S. aureus are given in Table 3. More than two-thirds of the strains proved to be methicillin-resistant S. aureus (MRSA) in both periods and appeared to be associated with gentamicin resistance. A pronounced decrease of resistance rates to trimethoprim/sulfamethoxazole and rifampin was shown in the 2nd period (2001–2003). Minocycline proved highly active against this pathogen in both periods. 4. Discussion Both the impact of the increasing bacterial resistance on the patient care and the importance of getting local microbiologic data for the management of patients with HAP have recently been reviewed (Koulenty and Rello, 2006; Diaz et al., 2007). However, few microbiologic surveillance studies have focused specifically on patients with HAP, and none of them have reported data limited only to BAL specimens with significant colony counts from patients with suspected HAP (Mathai et al., 2001; Gales
Table 2 Resistance profiles of the most frequent Gram-negative roads recovered from BAL of patients hospitalized in Argentina from 1997 to 2003 with suspected HAP Antibiotic
Resistance (%) at the following periods Acinetobacter spp
P. aeruginosa
K. pneumoniae
1997–2000 (n = 89) 2001–2003 (n = 95) 1997–2000 (n = 77) 2001–2003 (n = 79) 1997–2000 (n = 33) 2001–2003 (n = 23) Ampicillin/sulbactam Ceftazidime Cefepime Piperacillin/ tazobactam Imipenem Amikacin Ciprofloxacin
70.8 94.3 83.1 93.2
71.6 92.6 80.7 92.6
NA 24.7 23.4 39.0
NA 25.3 25.3 38.0
72.7 51.5 36.4 33.3
73.9 56.5 47.8 26.0
24.7 87.6 88.8
48.4 76.8 91.6
31.6 32.5 46.7
23.4 33.0 53.2
0 36.4 27.3
0 26.0 30.4
Comparative analysis between 2 periods. Numbers in boldface indicate the only statistically significant difference between periods (P b 0.001). Ceftazidime resistance in K. pneumoniae represents all strains with phenotype of ESBL producer. It should be noted that ampicillin/sulbactam results against Acinetobacter cannot be extrapolated to sulbactam MIC because, solely, sulbactam is the active compound. NA = not assayed.
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et al., 2002), as our study did. To our knowledge, the present study is the 1st nationwide surveillance approaching this issue. We consider that this is a major fact, as the likelihood of including colonizer organisms might be minimized by restricting the analysis solely to microbiologically significant organism from BAL specimens of patients with suspected HAP. Nevertheless, the frequency of S. aureus, P. aeruginosa, and K. pneumoniae we found was similar to that reported by the SENTRY Program in North America and Latin America (Mathai et al., 2001; Gales et al., 2002), as well as to that collected from 1689 episodes of VAP documented by bronchoscopic techniques in 24 studies performed in the United States and Europe (Chastre and Fagon, 2002). By contrast, we have observed a higher frequency of Acinetobacter spp. (24.5% in our study versus 2.8%, 9.6% and 7.9% reported by the SENTRY program in North America, in Latin America, and in the VAP episodes of USA–Europe, respectively). Although the SENTRY studies included hospitalized patients without distinction between community-acquired pneumonia and HAP (Mathai et al., 2001; Gales et al., 2002), the difference seems to be too wide to be attributable only to this situation. In addition, the frequency is also much higher than that described for the patients with VAP in the United States and Europe (Chastre and Fagon, 2002). In the present study, Acinetobacter displayed high rate of bacterial resistance to most antibiotics. The frequency of imipenem resistance (25%) shown in the period 1997 to 2000 is higher than that described by the SENTRY for Latin America along the same period (15%) (Gales et al., 2002). In fact, this rate for Latin America as a whole in the SENTRY study might have been influenced by the 2 Argentinean centers participating in this program, as both of them are from the same area and displayed an imipenem resistance frequency by Acinetobacter of 40% in a tailored study reported by the SENTRY (Tognim et al., 2000). It is noteworthy that the imipenem resistance rate we found in the period 1997 to 2000 is also higher than that reported by ourselves in Argentina in a previous period (9% between 1996 and 1998) (Bantar et al., 2000), and it was doubled in the period 2001 to 2003. Therefore, these findings suggest that a sustainable increase in imipenem resistance by Acinetobacter spp. is occurring in Argentina since 1996. Indeed, this resistance was reported early in our country (Brown et al., 1998), and its mechanism and spread is currently under discussion (Brown et al., 2005; Merkier and Centron, 2006). Four different clusters (A, B, C, and E) of imipenem-resistant Acinetobacter expressing the ARI-2 enzyme (currently named OXA-51) were described in 3 Argentinean centers between 1994 and 1998, suggesting transferable spread of imipenem resistance in Argentina (Brown et al., 2005). The frequency of K. pneumoniae strains with phenotype of ESBL producer is much higher in our study (more than 50%) than that reported by the SENTRY in the United States (5%) and in Latin America (29%) (Mathai et al., 2001; Gales et al., 2002). The presence of ESBL in our country was 1st
reported by Casellas and Goldberg (1989). Two indigenous novel ESBLs were described in Argentina, CTX-M-2 (Bauernfeind et al., 1992) and PER-2 (Bauernfeind et al., 1996). Early epidemiologic studies performed by Galas et al. (1998) and Galas et al. (1999) demonstrated that CTX-M-2 (64–70%) and, to a lesser degree, SHV-1 derivates (i.e., SHV-2 and SHV-5, 11–20%) and PER-2 (5–10%) were the most prevalent ESBLs among a number of Argentinean K. pneumoniae and E. coli strains, a more recent study that this situation remains unchanged (Quinteros et al., 2003). MRSA was highly prevalent in our study. In 1999, Corso et al. (1999) reported a clonal typing study among 148 isolates of methicillin-resistant S. aureus collected by 13 hospitals from Argentina. These authors stated that the prevalent clone (62% of the isolates) had a pulsed-field gel electrophoresis pattern similar to that of the Brazilian isolates, that is, the clone XI∷B∷B. This clone was also resistant to gentamicin, macrolides, rifampin, tetracycline, trimethoprim/sulfamethoxazole, and ciprofloxacin. This multiresistant phenotype was shown in the 1st period of the present study (1997–2000). Interestingly, most MRSA strains recovered from the BAL in the 2nd period, 2001 to 2003, proved susceptibility to trimethoprim/sulfamethoxazole and rifampin. In 2002, a novel MRSA clone carrying the SCCmec type I element with this susceptibility pattern was characterized in Córdoba, Argentina (Sola et al., 2002; Sola et al., 2006), and the replacement of the previous resistant clone by this more susceptible one was subsequently reported (Gardella et al., 2005). These findings might explain our results with the BAL samples. The present study shows the worrisome increasing bacterial resistance in BAL samples to most available antimicrobial options for treating patients with suspected HAP. Variations over time support the need for a systematic tailored surveillance and compel us to establish a rational usage of antimicrobial agents in our country.
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