Proteínas Ligadoras de Penicilinas

2. Revisão Bibliográfica

2.4. Mecanismos de Resistência aos β-lactâmicos em P aeruginosa

2.4.4. Proteínas Ligadoras de Penicilinas – PBPs

Proteínas ligadoras de penicilinas (PBPs) são enzimas localizadas na membrana citoplasmática e constituem o sítio de ação para a classe de antimicrobianos dos β-lactâmicos. Essas enzimas estão envolvidas nas etapas finais da síntese do peptideoglicano. As PBPs se ligam covalentemente aos β-lactâmicos impedindo a formação da parede celular, causando a lise

Revisão Bibliográfica

Página 32 osmótica da célula. O número de PBPs podem variar de acordo com cada espécie e são denominadas numericamente de acordo com o peso molecular; quanto maior o peso molecular, menor a numeração que recebem (Strateva & Yordanov 2009; Zavascki et al., 2010). As PBPs podem ser apresentadas em diferentes espécies e gêneros com a mesma denominação, e não necessariamente serem relacionadas (Poole 2004; Zapun et al., 2008; Strateva & Yordanov 2009; Zavascki et al., 2010). A resistência aos antimicrobianos β-lactâmicos devido a alterações nas PBPs é mais comum em micro-organismos Gram positivos do que nos micro-organismos Gram negativos (Godfrey et al., 1981; Gotoh et al., 1998).

Até o momento, sete diferentes PBPs foram descritas em P. aeruginosa: 1a, 1b, 2, 3, 4, 6 e 7. As PBPs -1a, -1b, -2 e -3 desempenham funções essenciais e não essenciais para a viabilidade da célula. Portanto, os carbapenens possuem afinididade para se ligarem à PBP-2, enquanto as cefalosporinas se ligam à PBP-3 (Strateva & Yordanov 2009; Zavascki et al., 2010). Apesar de pouco frequentes, alterações nas PBPs já foram descritas em isolados clínicos de P.

aeruginosa. Dois estudos relataram a alteração na PBP-4 em isolados de P. aeruginosa após

tratamento com imipenem e com piperacilina/tazobactam. Em outro estudo, também foi sugerido que a resistência aos β-lactâmicos em P. aeruginosa poderia estar associada a um aumento na produção da PBP-3 (Strateva & Yordanov 2009; Zavascki et al., 2010).

Em 2010, um estudo descrito por Moyá e seus colaboradores, apresentou um inibidor potente para a PBP-3 e a PBP-1b, sendo chamado de CXA-101, ceftolozane (nova Cefalosporinases anti - Pseudomonas). O mesmo estudo verificou que o imipenem foi o inibidor mais potente para a PBP-2 e PBP-1c. Além disso, o CXA-101, assim como a ceftazidima e ao contrário do imipenem, demonstrou ser um indutor muito fraco de expressão da AmpC, devido a baixa afinidade com a PBP-4. Já no estudo de Zamorano e colaboradores (2010) demonstrou que a hiperprodução de AmpC é o mecanismo mais comum de resistência à penicilina e as

Revisão Bibliográfica

Página 33 cefalosporinas em isolados clínicos de P. aeruginosa, sendo impulsionado por mutações no gene

ampD ou pela inativação do gene dacB, que codifica a PBP-4. Entretanto quando ocorre a

inativação do gene nagZ, os autores verificaram uma redução drastica na capacidade de isolados de P. aeruginosa em desenvolver resistência a ceftazidima e com isso não expressão da PBP-4. Os autores concluíram que NagZ é um candidato para a reversão e prevenção da resistência aos β-lactâmicos.

Apesar da ausência de diferenças significativas na expressão do gene ou sequência, uma clara tendência para o aumento da PBP2 (imipenem) e da PBP3 (ceftazidima, ceftolozane e imipenem) foi observado em isolados de P. aeruginosa apresentando panresistência aos β- lactâmicos. Sendo assim, sugere-se que, além da AmpC, dos sistemas de efluxo, e da OprD, alterações nas PBPs parece desempenhar um papel importante no aparecimento da panresistência em P. aeruginosa (Moyá et al., 2012).

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Objetivos

Página 35 3.1 Objetivo Principal

Avaliar se a presença de ES-OXA poderia estar contribuindo para o fenótipo de redução de sensibilidade à cefepima.

3.2 Objetivos Secundários

Padronizar uma técnica de PCR-multiplex para detecção dos diferentes grupos de oxacilinases descritas em P. aeruginosa;

Avaliar se a DDST seria capaz de discriminar os isolados produtores de ES-OXA daqueles produtores de oxacilinases de espectro restrito;

Analisar o perfil de sensibilidade aos antimicrobianos nas amostras de P. aeruginosa produtoras de oxacilinase;

Avaliar a similaridade genética entre os isolados de P. aeruginosa produtores de oxacilinases e demais β-lactamases;

Caracterizar molecularmente as oxacilinases encontradas nos isolados clínicos de P.

aeruginosa isolados durante o período de 15 anos;

Estudar a frequência dos genes codificadores de ESβL mais comumente encontrados em P. aeruginosa isolados no Brasil.

Apresentação

Página 37 Os resultados da presente tese de mestrado serão apresentados na forma de artigo científico, que será posteriormente submetido ao periódico “Antimicrobial Agents and Chemotherapy (AAC)”. Dados parciais desse estudo serão apresentados na forma de pôster (nº C2-1594) na seção “Epidemiology of Resistance in Pseudomonas and Acinetobacter” no “53th Interscience Conference on Antimicrobial Agents and Chemotherapy - ICAAC” a ser realizado na cidade de Denver, Colorado, EUA, entre os dias 10 a 13 de Setembro de 2013. Para a finalização da padronização das reações de PCR multiplex e convencional para a detecção dos diferentes grupos de oxacilinases avaliados no estudo, estamos aguardando o envio dos controles positivos solicitados aos respectivos grupos de pesquisa no exterior que ainda estão faltando (OXA-5, OXA-20, OXA-45, OXA-46 e OXA-198). Sendo assim, a foto do gel de agarose (Figure 1, página 68) somente consta os controles para alguns grupos de oxacilinases (OXA-1, OXA-2, OXA-10 e OXA-18).

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Página 39 Temporal Distribution of Oxacilinases Encoding Genes in Cefepime Non-Susceptible

Pseudomonas aeruginosa Clinical Isolates

2 3

Fernanda Villas Boas Petrolini1_{, Rodrigo Cayô}1*_{, Ana Carolina Ramos da Silva¹, Graziela Braun¹,}

Eloiza Helena Campana1_{, Renata Cristina Picão}2_{, Ana Cristina Gales}1_.

5 6

1_{Laboratório ALERTA, Disciplina de Infectologia, Departamento de Medicina, Universidade}

Federal de São Paulo - UNIFESP, São Paulo, Brazil.

2_{Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo Goes, Universidade}

Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, Brazil.

10 11

Running Title: OXA enzymes in Pseudomonas aeruginosa.

12 13

*Corresponding Author. Current Address: Laboratório ALERTA, Universidade Federal de São

Paulo - UNIFESP, Rua Pedro de Toledo, 781, 6th_{floor, Vila Clementino, 04039-032, São Paulo -}

SP, Brazil. Phone/Fax.: +55 11 55764748. E-mail: rodrigocayosilva@gmail.com.

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Página 40 ABSTRACT

Initially, multiplex and single PCR reactions were standardized using specific primers to detect

and sequence all narrow and extended-spectrum oxacilinases detected in P. aeruginosa. Then,

the presence of genes encoding oxacilinases was evaluated among 231 unique Pseudomonas

aeruginosa isolates not susceptible to cefepime (CNS-PSA) collected between the years 1997

and 2011 from a Brazilian teaching hospital. The bacterial identification was confirmed by MALDI-

TOF MS. All isolates harbored blaOXA-50 that codifies a chromosomal encoded narrow-spectrum

oxacilinase. The frequency of oxacilinases among the CNS-PSA was 17.7%, with blaOXA-56 being

the most frequent followed by blaOXA-2 (1.3%) and blaOXA-4 (0.90%). Additionally, other β-

lactamase encoding genes were also found: blaCTX-M-2 (31.6%), blaSPM-1 (5.6%), blaSHV-5 (2.2%),

blaGES-1 (1.7%) and blaTEM-1 (0.4%). Association of blaOXA-2 with blaGES-1 or blaOXA-56 with blaGES-1 or

blaSPM-1 was also observed. Spread of epidemic clones carrying blaOXA-2, blaOXA-4, and blaSHV-5

was noticed. In contrast, genetic heterogeneity was observed among those isolates possessing

blaOXA-56 and blaCTX-M-2, which were the most frequent β-lactamases detected in the periods of

1997 to 2001 and 2004 to 2011, respectively. Despite of a great diversity of β-lactamases

encoding genes found among CNS-PSA in a Brazilian tertiary teaching hospital during a 15-year

period, the resistance to cefepime could not be attributed to the emergence and/or spread of

extended-spectrum oxacilinase producing strains.

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Página 41 INTRODUCTION

P. aeruginosa is a leading cause of infectious disease in hospitalized patients (1).

According to the SENTRY Antimicrobial Surveillance Program, P. aeruginosa was the most

common pathogen causing pneumonia, and ranked as the third and fifth most frequent agent

causing skin and soft tissue and bloodstream infections in Latin America, respectively (2).

Treatment of infections caused by P. aeruginosa is usually difficult due to its innate resistance to

multiple antimicrobials. In addition, this pathogen possesses a remarkable ability of acquiring

other mechanisms of resistance (1). The development of resistance to β-lactams in P. aeruginosa

is associated with overexpression of intrinsic cephalosporinase AmpC and efflux systems, outer

membrane impermeability and mainly the acquisition of transferable genes encoding a variety of

β-lactamases (3). A growing number of Ambler class A extended-spectrum β-lactamases

(ESβLs), metallo-β-lactamases (MBLs) and extended-spectrum class D oxacilinases (ES-OXAs)

have been reported in clinical isolates of P. aeruginosa worldwide (4,5,6,7).

The β-lactamase production is the most frequent and dynamic mechanism of resistance

to β-lactams in P. aeruginosa. It compromises drastically the clinical use of these antimicrobial

agents and directly impacts on treatment and clinical outcomes (8,9). During the past decades,

the persistent exposure of bacterial strains to a variety of β-lactam agents has promoted and

selected continuous changes on structure the β- lactamases and expansion of their activity (10).

Among them, the class D β-lactamases or oxacilinases (OXAs) is a diverse and heterogenic

group containing more than 350 variants described so far that includes narrow- or extended-

spectrum β-lactamases (ES-OXA), and carbapenemases (CHDLs) (11,12,13).

Although a multiplex-PCR has been proposed for detection of CHDLs founded mostly in

Acinetobacter baumannii (14), there is no rapid and discriminative molecular test to identify other

non-CHDLs oxacilinases, which are commonly described in P. aeruginosa (15). Besides, differing

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Página 42 from other frequent ESβLs, like TEM and SHV groups, non-CHDLs oxacilinases do not always

show a progression towards broad-spectrum of activity compared to their ancestors making even

more difficult their recognition and classification (11,12,13,16). The recognition of the ESβLs

phenotype is of paramount importance for prescription of adequate therapy and implementation

of infection control measures. The majority of ESβLs types are detected by double disc synergy

(DDST) using clavulanate as inhibitor. ES-OXA isolates can be also detected based on inhibition

of their activity by sodium chloride; however, these tests often underestimate the frequency of

ES-OXA since the presence of this group of enzymes is generally masked by the co-production of

other β-lactamases in P. aeruginosa (12,13,15).

Cefepime and ceftazidime are broad-spectrum cephalosporins that display similar

potency against Pseudomonas aeruginosa (2). Both antimicrobials have been widely used to

treat moderately ill patients. In our hospital, we have observed, clinical isolates

of P. aeruginosa presenting lower susceptibility to cefepime than to ceftazidime during recent

years. This phenotype has been related to hyperproduction of the efflux system MexXY-OprM

and/or the production of OXA-31, OXA-35, PSE-1 or CTX-M-2.

The objective of this study was to evaluate the frequency of β-lactamases encoding

genes, including narrow and ES-OXA, in a large collection of cefepime non-susceptible P.

aeruginosa isolates that could justify this phenotype of resistance (This work was presented in

part as Poster at the 53th_{Interscience Conference on Antimicrobial Agents and Chemotherapy -}

ICAAC at Denver, CO, USA, 2013).

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Página 43 MATERIAL AND METHODS

Standardization of Multiplex PCR for oxacilinase detection. To design the primers for

oxacilinase detection the currently available reference accession numbers of 350 oxacilinases

encoding genes were obtained from the Lahey website (http://www.lahey.org/Studies/). All

nucleotide sequences were downloaded from GenBank (National Center for Biotechnology

Information, National Institutes of Health, Bethesda, MD) and aligned. A dendrogram was

constructed using the program Lasergene DNAstar MegAling version 7.0.0 (DNASTAR, Madison,

USA) from the phylogenetic analysis using the software "Multiple Sequence Alignment - Clustal

W". Based on the homology of the nucleotide sequences, the oxacilinases described in P.

aeruginosa were grouped and consensus sequences were obtained for each of the oxacilinases

encoding genes (Table 1). Primers for detection and sequencing for each cluster were designed

for multiplex PCR to obtain at least 100 bp difference in the sizes of amplicons using the "Primer

3" version 0.4.0 (http://frodo.wi.mit.edu/ accessed January 2013) as described in Table 2. For the

most common narrow and ES-OXA genes groups were included in the multiplex PCR and for

another, a single PCR were developed. A single PCR was developed for cromossomal or

infrequently β-lactamase encoding genes as well as for confirmation of the multiplex results. For

standardization and optimization of PCR reactions for oxacilinase detection, oxacilinase-

producing control strains representatives of each OXA group identified in P. aeruginosa were

tested.

97 98

Bacterial isolates. A total of 231 cefepime non-susceptible P. aeruginosa clinical isolates

collected from patients hospitalized at Complex Hospital São Paulo between January 1997 and

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August 2011 were studied. All isolates were stored at -20°C in the bank of microorganisms of the

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Clinical Special Laboratory of Microbiology - LEMC, Division of Infectious Diseases, Federal

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Página 44 University of São Paulo - UNIFESP. The identification and susceptibility test was initially

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performed by PhoenixTM_{Automated Microbiology System (Becton Dickinson, USA). Identification}

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of P. aeruginosa isolates was confirmed by Matrix Assisted Laser Desorption Ionization - Time of

105

Flight (MALDI-TOF MS) (17).

106 107

DNA preparation. The P. aeruginosa clinical isolates and control strains were grown on blood

108

agar plates overnight at 37ºC to ensure colony purity. Three to five bacterial colonies were taken

109

from the blood agar plates and suspended in 350 µL of Milli-Q®_{sterile water (Billerica, MA, USA).}

110

One microliter of this bacterial suspension was used as templates for further amplification (18).

111 112

Multiplex PCR technique. PCR reactions were prepared in a laminar flow containing master mix

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("GoTaq Green Master Mix", Promega, Madison, USA), sterile water (Water, Molecular Biology

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Grade, Eppendorf AG, Hamburg, Germany) and oligonucleotides (Invitrogen, Carlsbad, USA).

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The thermocycling conditions and primers used in the PCR reactions are also shown in Table 2.

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For the multiplex reaction assembly were used: 10.0 µL of master mix, 0.25 µL of each primer

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(sense and anti-sense) designed for groups of blaOXA-1-like, blaOXA-2-like, blaOXA-5, blaOXA-18, blaOXA-45,

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blaOXA-46 and 0.75 mL of each primer (sense and anti-sense) designed for a group of blaOXA-10-like,

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4.5 µL of sterile deionized water, and 1.0 µL of template (sample or positive control). For single

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PCR reactions, 10.0 µL of master mix, 0.5 µL of each primer (sense and anti-sense) designed

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for detection of blaOXA-1-like, blaOXA-2-like, blaOXA-3-like, blaOXA-5, blaOXA-7-like, blaOXA-18, blaOXA-20-like,

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blaOXA-45, blaOXA-46 and blaOXA-198, 8 µL of sterile deionized water and 1.0 µL of template were

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tested. In addition, other commonly genes encoding for other ESβLs (blaCTX-M-like, blaSHV-like,

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blaTEM-like and blaGES-like), as well as, genes enconding for MβLs (blaIMP-like, blaVIM-like, blaSPM-1,

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blaGIM-1, blaSIM-1 and blaNDM-like) were also evaluated, as previously published (18,19,20). The

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Página 45 revelation of the multiplex PCR products were performed by electrophoresis in 2% agarose gels

127

(Agarose UltrapureTM_{Invitrogen, Carlsbad, USA) while conventional PCR was performed by}

128

electrophoresis on 1% agarose gels, 110V for 50 min in 0.5X TBE buffer (89 mM Tris-borate and

129

2 mM EDTA, pH 8.0). "DNA ladder" 100 bp was used as molecular weight marker (Invitrogen,

130

Carlsbad, USA). The gels were stained with ethidium bromide (2.5 mg/mL) for 30 minutes and the

131

bands were visualized under ultraviolet light - 320 nm (GelDoc Quantity One, Bio-Rad

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Laboratories, USA).

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Sequencing and interpretation of results. The sequencing reactions were carried out from the

135

purification of the products obtained in PCR reactions using the "QIAquick Gel Extraction Kit"

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(Qiagen, Courtaboeuf, France) according to manufacturer instructions. Quantification of genomic

137

DNA was determined by optical density in a spectrophotometer digital "NanoVue Plus

138

Spectrophotometer" (GE Healthcare, Canada) using 2 µL of total DNA purified. After the

139

measurement, approximately 70 ηg of DNA was subjected to preparatory sequencing reaction

140

using the "Kit BigDye Terminator Cycle Sequencing" (Applied Biosystems, Foster City, USA). The

141

sequencing reactions were performed on the machine "ABI 3500 Genetic Analyzer" (Applied

142

Biosystems, Perkin Elmer, USA). The DNA sequences and the derived protein sequences

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obtained were analyzed using the "Lasergene Software Package" (DNASTAR, Madison, USA)

144

and then compared to those sequences deposited in the "GenBank".

145 146

Strain-tailored double-disk synergy test (DDST) for ES-OXA detection. P. aeruginosa

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isolates carrying blaOXA were tested by a DDST as described by Hocquet and colleagues.

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Mueller- Hinton (MH) agar plates were inoculated with 0.5 McFarland bacterial suspension of

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each strain and disks of ceftazidime (30 µg) and cefepima (30 µg) were placed 30 mm apart of

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Página 46 amoxicillin-clavulanate (10 µg) or imipenem (10 µg). The plates were incubated aerobically at

151

35°-37°C for 18-20 h (15). The phenotypic detection of oxacilinase was considered positive if a

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distortion in the β-lactam inhibition zones was noticed. OXA-18-producing P. aeruginosa and

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PAO1 P. aeruginosa strains were tested as positive and negative quality controls, respectively.

154 155

Antimicrobial susceptibility testing. The minimum inhibitory concentrations (MIC) for all

156

oxacilinases-producing P. aeruginosa clinical isolates were determined by broth microdilution

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following the recommendations of the "Clinical and Laboratory Standards Institute - CLSI” (21).

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The following antimicrobials were tested: piperacillin/tazobactam, ceftazidime, cefepime,

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aztreonam, imipenem, meropenem, ciprofloxacin, amikacin, gentamicin and polymyxin B. The

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powders of antimicrobial agents were purchased from Sigma-Aldrich (Sigma, Steinheim,

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Germany). The susceptibility results were interpreted according with the CLSI breakpoints (22).

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Escherichia coli ATCC 25922 and P. aeruginosa ATCC 27853 were tested as quality control

163

strains.

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Genetic similarity and cluster analysis. Genetic similarity among oxacilinases-producing P.

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aeruginosa isolates was evaluated by ERIC-PCR using randomic primers as described previously

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(23). Analysis of ERIC patterns was performed by visual inspection of photographs of ethidium

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bromide-stained 2% agarose gels. Dendrogram and cluster analysis were performed using

169

algorithms available within the BioNumerics software package v.6.0 (Applied Maths, Sint-

170

Martens-Latem, Belgium). Percent similarity between different chromosomal fingerprints was

171

scored by the Dice coefficient. The unweighted pair group method with arithmetic means

172

(UPGMA), with a 1.00% tolerance limit and 1.00% optimization, was utilized to obtain the

173

dendrogram.

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Página 47 RESULTS

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Multiplex PCR for detection of narrow- and ES-OXA standardization. Based on the

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nucleotide sequences, the 52 oxacilinases described in P. aeruginosa were divided in ten

177

different groups as follow: OXA-1 group (5 variants), OXA-2 group (10 variants), OXA-5 group

178

(one variant), OXA-10 group (18 variants), OXA-18 group (one variant), OXA-20 group (two

179

variant), OXA-45 group (one variant), OXA-46 group (three variant), OXA-50 group (10 variants)

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and OXA-198 group (one variant). The respective variants of each group and their spectrum of

181

activity are shown on Table 3. The most frequent groups of narrow- and ES-OXA described in P.

182

aeruginosa isolates (OXA-1, OXA-2, OXA-5, OXA-10, OXA-18, OXA-45 and OXA-46) were

183

included in the multiplex PCR and a single PCR was developed for the remaining groups (OXA-

184

20, OXA-50 and OXA-198). The amplicons showed the expected sizes of for all control strains,

185

confirming the specificity of each pair of primers to detect the narrow- and ES-OXA groups as

186

demonstrated in Figure 1.

187 188

β-lactamases production in cefepime non-susceptible P. aeruginosa isolates. A total of 231

189

cefepime non-susceptible P. aeruginosa isolates were recovered from January 1997 to August

190

2011 in a tertiary teaching hospital localized in São Paulo city, Brazil. All P. aeruginosa isolates

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carried the cromossomal blaOXA-50-like gene that encoded a narrow-spectrum oxacilinase intrinsic

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to this pathogen. Then, as expected, all isolates were identified as P. aeruginosa by MALDI-TOF

193

MS with a high score ≥ 2.3. Among them, the multiplex PCR was performed and detected the

194

presence of acquired oxacilinases encoding genes in 41 isolates (17.7%). The blaOXA-10 group

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was found in 36 of 41 isolates (87.8%) followed by blaOXA-2 and blaOXA-1 detected in 3 (7.3%)

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and 2 (4.9%) of 41 isolates, respectively. blaOXA-5, blaOXA-18, blaOXA-20, blaOXA-45, blaOXA-46, and

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blaOXA-198 groups were not detected among the P. aeruginosa isolates evaluated. DNA

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Página 48 sequencing results revealed that the blaOXA-56 (OXA-10 group) that codifies OXA-56, a narrow-

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spectrum oxacilinase, was the most frequent oxacilinases among the P. aeruginosa isolates

200

evaluated during the 15-year period of study, followed by the blaOXA-2 (OXA-2 group) and blaOXA-

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4 (OXA-1 group) that codify OXA-2 and OXA-4 narrow-spectrum oxacilinases, respectively. Other

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β-lactamase encoding genes were also found: blaCTX-M-2 (ESβL; 73 isolates/31.6%), blaSPM-1

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(MβL; 13 isolates/5.6%), blaSHV-5 (ESβL; 5 isolates/2.2%), blaGES-1 (ESβL; 4 isolates/1.7%) and

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blaTEM-1 (narrow-spectrum; 1 isolate/0.4%). The concomitant presence of blaOXA-56 with blaGES-1 or

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blaSPM-1 was found in one and six isolates, respectively, as well as blaOXA-2 with blaGES-1 in one

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isolate (Figure 3). Thus, among the 231 isolates evaluated in the present study, 128 isolates

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(55.4%) possessed at least one acquired β-lactamase encoding gene of the eight genes

No documento Estudo da Frequência Temporal e Padronização de uma PCR Multiplex. para a Detecção de Oxacilinases em Isolados Clínicos de Pseudomonas. (páginas 51-150)