Belén Aracil

Spread of Escherichia coli Strains with High-Level Cefotaxime and Ceftazidime Resistance between the Community, Long-Term Care Facilities, and Hospital Institutions

ABSTRACT A total of 151 Escherichia coli strains resistant to cefotaxime and ceftazidime were isolated during a prospective surveillance study. These strains were characterized by clinical, microbiological, and molecular analyses and were distributed into four clusters of 103, 11, 6, and 5 isolates, along with 25 unrelated strains. The principal cluster was isolated from urine, wound, blood, and other samples in three hospitals, eight nursing homes, and a community healthcare center. This cluster was associated with both nosocomial (65%) and community-acquired (35%) infections. Most strains were resistant to ciprofloxacin, gentamicin, tobramycin, cefepime, amoxicillin-clavulanic acid, and trimethoprim-sulfamethoxazole but were susceptible to imipenem. All isolates from the four clusters expressed the extended-spectrum β-lactamase (ESBL) CTX-M-15. This enzyme was also present in 8 (30.8%) of the 26 unrelated isolates. The other ESBLs, CTX-M-14 and CTX-M-32, were detected in five and seven cases, respectively, but they were detected in individual E. coli isolates only. In three clusters, blaCTX-M-15 alleles were linked to an ISEcp1-like element, while in eight strains of cluster II an IS26 element preceded the blaCTX-M-15 allele. An additional pool of resistance genes included tetA, drfA14 or dfrA17, sul1 or sul2, aac(6′)Ib, and aac(3)IIb. All except one of the 27 isolates tested for genetic virulence markers harbored the same three virulence genes: iutA and fyuA (siderophores), and traT (serum survival factor). Epidemic or occasional isolates of cefotaxime- and ceftazidime-resistant E. coli can spread between distinct health facilities including hospitals, community health centers, and long-term care centers.

Analysis of Invasive Haemophilus influenzae Infections after Extensive Vaccination against H. influenzae Type b

ABSTRACT Little clinical and microbiological information is available about invasive Haemophilus influenzae infection after widespread vaccination against H. influenzae type b (Hib). We conducted an active community surveillance study on invasive H. influenzae during a 2-year period in a community of more than 5 million people after vaccination against Hib in children was introduced. The median incidence was 16.3 cases/100,000 persons per year in children less than 1-year-old and 4.41 cases/100,000 persons in children less than <5 years old. The highest incidence in adults was observed in patients greater than 70 years old. Clinical diagnoses included bacteremia, pneumonia, and meningitis. Of the H. influenzae-infected patients, 74.3% had underlying predisposing conditions, including impaired immunity and respiratory diseases. A total of 73.6% of the isolates were nontypeable and 16.5, 6.6, and 3.3% were types b, f, and e, respectively. Infections due to capsulated strains b, e, and f were evenly distributed between children and adults. Ampicillin and cotrimoxazole resistance occurred at frequencies of 24.2 and 48.4%, respectively. Antibiotic resistance was more prevalent in capsulated than in noncapsulated H. influenzae. Invasive isolates were highly resistant to antibiotics that were used infrequently in the community. Nontypeable H. influenzae were genetically much more heterogeneous than capsulated strains. Capsule-deficient mutants (b−) were not detected. Plasmid carriage was linked to antibiotic resistance and capsulated strains. Over the study period, the incidence of invasive H. influenzae infections, either encapsulated or not, did not increase. In the post-Hib vaccination era, most invasive infections were due to noncapsulated strains and occurred in the extreme ages of life in patients with predisposing conditions.

Carbapenemase-Producing Enterobacteriaceae in Spain in 2012

ABSTRACT We report the epidemiological impact of carbapenemase-producing Enterobacteriaceae (CPE) in Spain in 2012. Of the 237 carbapenemases detected, 163 were from the OXA-48 group, 60 were from VIM-1, 8 were from KPC-2, 5 were from IMP, and 1 was from NDM-1. Interhospital spread of carbapenemase-producing Klebsiella pneumoniae was due to a limited number of multilocus sequence types (MLST) and carbapenemase types, including ST15–VIM-1, ST11–OXA-48, ST405–OXA-48, ST101–KPC-2, and ST11–VIM-1. The number of CPE cases in Spain has increased sharply in recent years, due mainly to the emergence of OXA-48.

Colonisation and infection due to Enterobacteriaceae producing plasmid-mediated AmpC β-lactamases

OBJECTIVES To investigate the epidemiology and clinical features of infections caused by Enterobacteria producing plasmid-mediated AmpC β-lactamases (pAmpC), which are emerging as a cause of resistance to extended-spectrum cephalosporins. METHODS A prospective multicentre cohort of patients with infection/colonisation due to pAmpC-producing Enterobacteriaceae was performed in 7 Spanish hospitals from February throughout July 2009. pAmpCs were characterised by PCR and sequencing. RESULTS 140 patients were included; organisms isolated were Escherichia coli (n = 100), Proteus mirabilis (n = 20), Klebsiella pneumoniae (n = 17), and others (n = 3). Overall, 90% had a chronic underlying condition. The acquisition was nosocomial in 43%, healthcare-associated in 41% (14% of those were nursing home residents), and community in 16%. Only 5% of patients had no predisposing feature for infection with multidrug-resistant bacteria. Nineteen percent of patients were bacteraemic. Inappropriate empirical therapy was administered to 81% of bacteraemic patients, who had a crude mortality rate of 48%. The most frequent enzyme was CMY-2 (70%, predominantly in E. coli and P. mirabilis) followed by DHA-1 (19%, predominantly in K. pneumoniae). CONCLUSION pAmpC-producing Enterobacteriaceae caused nosocomial, healthcare-associated and community infections mainly in predisposed patients. Invasive infections were associated with high mortality which might be partly related to inappropriate empirical therapy.

Prevalence of Human Immunodeficiency Virus Type 1 (HIV-1) Non-B Subtypes in Foreigners Living in Madrid, Spain, and Comparison of the Performances of the AMPLICOR HIV-1 MONITOR Version 1.0 and the New Automated Version 1.5

ABSTRACT Plasma specimens collected in 1999 from 32 human immunodeficiency virus type 1 (HIV-1)-infected foreigners living in Madrid, Spain, were examined for the presence of non-B subtypes. Furthermore, plasma viremia was quantified using two different AMPLICOR HIV-1 MONITOR tests, version 1.0 and the new upgraded and automated version 1.5 (COBAS). Most patients came from Africa, where they most likely had acquired HIV-1 infection through sexual contact. HIV-1 genetic subtyping was based on the phylogenetic analysis of theprotease gene. Twenty-two subtype B, six subtype G, two subtype C, one subtype A, and one D subtype infection were found. Overall, non-B subtypes represented 31.25% of the study population. Irrespective of the HIV-1 variant, viral load values above the detection limit (200 HIV RNA copies/ml) increased from 56.2 to 71.9% for results obtained using MONITOR version 1.0 and COBAS, respectively. Moreover, significant differences in viral load values (>0.5 logs) were recognized in up to 37.5% of samples. In summary, COBAS seemed to be more reliable for testing plasma viral load in HIV-infected immigrants living in Spain, one third of whom carried non-B subtypes.

Laboratory Detection of Haemophilus influenzae with Decreased Susceptibility to Nalidixic Acid, Ciprofloxacin, Levofloxacin, and Moxifloxacin Due to gyrA and parC Mutations

ABSTRACT The detection of clinical isolates with decreased fluoroquinolone susceptibilities and a resistance mechanism is of epidemiological and clinical interest. We studied the susceptibilities of 62 clinical isolates and 2 American Type Culture Collection reference strains of Haemophilus influenzae to ciprofloxacin, levofloxacin, moxifloxacin, and nalidixic acid by the microdilution and disk diffusion methods. The ciprofloxacin MICs for 34 of the isolates were ≥0.12 μg/ml (range, 0.12 to 32 μg/ml), and the ciprofloxacin MICs for 28 matched control isolates were ≤0.06 μg/ml. In addition, we sequenced the quinolone resistance-determining regions (QRDRs) of gyrA and parC of all strains. The log2 MICs of all quinolones were plotted against the inhibition zone diameters. The MICs and inhibition zone diameters selected to screen for the resistance mechanism were based on the susceptibility distribution data and the presence or absence of amino acid changes in the QRDRs of GyrA and ParC. Strains for which ciprofloxacin MICs were ≤0.06 μg/ml, levofloxacin and moxifloxacin MICs were ≤0.03 μg/ml, and nalidixic acid MICs were ≤2.0 μg/ml lacked modifications in the QRDR of GyrA. In contrast, all strains for which ciprofloxacin, levofloxacin, and moxifloxacin MICs were ≥0.5 μg/ml and the vast majority of those for which nalidixic acid MICs were ≥32 μg/ml exhibited amino acid changes in GyrA and ParC. Nalidixic acid and the other three fluoroquinolones studied could be used to screen H. influenzae isolates for the detection of decreased susceptibilities to quinolones due to the acquisition of two amino acid changes in the QRDRs of GyrA and ParC (sensitivity, >95%; specificity, >80%).

Spanish Multicenter Study of the Epidemiology and Mechanisms of Amoxicillin-Clavulanate Resistance in Escherichia coli

ABSTRACT We conducted a prospective multicenter study in Spain to characterize the mechanisms of resistance to amoxicillin-clavulanate (AMC) in Escherichia coli. Up to 44 AMC-resistant E. coli isolates (MIC ≥ 32/16 μg/ml) were collected at each of the seven participant hospitals. Resistance mechanisms were characterized by PCR and sequencing. Molecular epidemiology was studied by pulsed-field gel electrophoresis (PFGE) and by multilocus sequence typing. Overall AMC resistance was 9.3%. The resistance mechanisms detected in the 257 AMC-resistant isolates were OXA-1 production (26.1%), hyperproduction of penicillinase (22.6%), production of plasmidic AmpC (19.5%), hyperproduction of chromosomic AmpC (18.3%), and production of inhibitor-resistant TEM (IRT) (17.5%). The IRTs identified were TEM-40 (33.3%), TEM-30 (28.9%), TEM-33 (11.1%), TEM-32 (4.4%), TEM-34 (4.4%), TEM-35 (2.2%), TEM-54 (2.2%), TEM-76 (2.2%), TEM-79 (2.2%), and the new TEM-185 (8.8%). By PFGE, a high degree of genetic diversity was observed although two well-defined clusters were detected in the OXA-1-producing isolates: the C1 cluster consisting of 19 phylogroup A/sequence type 88 [ST88] isolates and the C2 cluster consisting of 19 phylogroup B2/ST131 isolates (16 of them producing CTX-M-15). Each of the clusters was detected in six different hospitals. In total, 21.8% of the isolates were serotype O25b/phylogroup B2 (O25b/B2). AMC resistance in E. coli is widespread in Spain at the hospital and community levels. A high prevalence of OXA-1 was found. Although resistant isolates were genetically diverse, clonality was linked to OXA-1-producing isolates of the STs 88 and 131. Dissemination of IRTs was frequent, and the epidemic O25b/B2/ST131 clone carried many different mechanisms of AMC resistance.

Significant ecological impact on the progression of fluoroquinolone resistance in Escherichia coli with increased community use of moxifloxacin, levofloxacin and amoxicillin/clavulanic acid

OBJECTIVES To determine trends in ciprofloxacin resistance and co-resistance to other antibiotic classes in blood isolates of Escherichia coli, and to investigate if there is an ecological relationship to the community use of fluoroquinolones and other antibiotics. METHODS Forty-two Spanish hospitals of the European Antimicrobial Resistance Surveillance Network collected ciprofloxacin and other antibiotic susceptibility data for non-duplicate consecutive E. coli isolates from patients with bacteraemia between 2001 and 2009. The nationwide ambulatory use of antibiotics between 1997 and 2008 was determined by WHO methods, and the co-evolution of both parameters was further analysed. RESULTS Of the 28 307 E. coli blood isolates, 27.9% were ciprofloxacin non-susceptible (CIPNS), increasing from 17.6% in 2001 to 32.7% in 2009. A continuous increase was observed between CIPNS and other resistances, including cephalosporin resistance due to the production of extended-spectrum β-lactamases (ESBLs) and non-susceptibility to both amoxicillin/clavulanic acid and tobramycin. Although the total use of antibiotics did not increase, community use of levofloxacin, moxifloxacin and amoxicillin/clavulanic acid increased by 307.2%, 62.6% and 70.1%, respectively. Yearly rates of CIPNS E. coli strongly correlated with the use of levofloxacin, moxifloxacin and amoxicillin/clavulanic acid (r(2 )> 0.80; P < 0.005 in all cases). CONCLUSIONS The rapid increase in CIPNS E. coli causing bacteraemia was closely related to the increase in resistance to amoxicillin/clavulanic acid, production of ESBLs and resistance to aminoglycosides. Community use of fluoroquinolones (mainly moxifloxacin and levofloxacin) and of amoxicillin/clavulanic acid represents a significant driver in the progression of fluoroquinolone resistance in bacteraemic E. coli.

Infections Due to Haemophilus influenzae Serotype E: Microbiological, Clinical, and Epidemiological Features

Surveillance after introduction of Haemophilus influenzae serotype b vaccination in Spain identified 26 H. influenzae serotype e (HiE) isolates. Of these, 16 (61.5%) were recovered from patients aged >16 years and 10 (38.5%) from children <16 years of age. HiE caused respiratory infections in 14 patients (9 with pneumonia), conjunctivitis in 4, vaginitis in 2, abscess in 2, and cellulitis, peritoneal infection, sepsis and meningitis in 1 patient each. HiE was strongly clonal and highly resistant to ampicillin and cotrimoxazole, and the incidence of HiE infection did not increase over time.

Low β-Lactamase-Negative Ampicillin-Resistant Haemophilus influenzae Strains Are Best Detected by Testing Amoxicillin Susceptibility by the Broth Microdilution Method

ABSTRACT Ampicillin resistance in Haemophilus influenzae due to alterations in penicillin-binding proteins (β-lactamase negative ampicillin resistant [BLNAR]) is acquiring increasing clinical and epidemiological importance. BLNAR strains with low ampicillin MICs (0.5 to 4 μg/ml) represent the majority of this population in Europe and the United States, but separating them from susceptible isolates is challenging. To investigate the best method to identify low-BLNAR strains, we studied the antibiotic susceptibilities of 94 clinical isolates of H. influenzae by microdilution, Etest, and disk diffusion: 25 had no resistance mechanisms (gBLNAS), 34 had mutations in the ftsI gene only (gBLNAR), 20 were β-lactamase producers only (gBLPAR), and 15 showed β-lactamase production and mutations in the ftsI gene (gBLPACR). By current CLSI breakpoints, most gBLNAR isolates were ampicillin susceptible by microdilution (76.5%) or by Etest (88.2%). Most gBLNAR strains (79.4%) were nonsusceptible to amoxicillin (the most widely used community antibiotic in the United States and Europe) when tested by microdilution. By Etest, 15% of β-lactamase-positive isolates were nonresistant to ampicillin or amoxicillin. The poorest agreement between Etest and microdilution results was for the gBLPAR isolates (25% for ampicillin, 15% for amoxicillin, and 10% for cefaclor). Low-strength disks of ampicillin and amoxicillin-clavulanic acid poorly identified low-BLNAR isolates and are not recommended as a screening method. We suggest new amoxicillin breakpoints for BLNAR isolates as follows: susceptible, MIC ≤ 0.5 μg/ml (no resistance mechanisms; pharmacokinetic/pharmacodynamic [PK/PD] data favorable); intermediate, MICs = 1 to 2 μg/ml (resistance mechanisms present but PK/PD data favorable), and resistant, MICs ≥ 4 μg/ml (resistance mechanisms present and PK/PD data unfavorable).