Risk Influence of Some Environmental and Behavioral Factors on Air Contamination in the Operating Room: An Experimental Study

Air contamination in operating rooms (ORs) depends on the conditions of the room and on activities therein performed. Methodologies of air quality assessment in ORs are often inadequately described in the scientific literature, and the time required for a change in status in air quality is never taken into account. The purpose of this study was to determine the influence of the state and the presence of human operators on air quality by implementing a precise measurement protocol that also took into account the time required for changes in the room to affect air pollution. As the main indicators of air pollution, bacterial load and concentration of airborne dust were measured. The results showed that: the use of surgical masks by operators in the OR did not significantly affect bacterial load within a distance of 2 m; keeping OR doors open did not induce a significant increase in bacterial load and of 5 μm particles while 10 μm particles concentration was positively affected; and air pollution measured with open doors was not significantly different from that due to the presence of two staff members, whether or not they were wearing masks. The results clarified the role of some factors on air pollution in ORs.

Resveratrol Reverts Tolerance and Restores Susceptibility to Chlorhexidine and Benzalkonium in Gram-Negative Bacteria, Gram-Positive Bacteria and Yeasts

The spread of microorganisms causing health-care associated infection (HAI) is contributed to by their intrinsic tolerance to a variety of biocides, used as antiseptics or disinfectants. The natural monomeric stilbenoid resveratrol (RV) is able to modulate the susceptibility to the chlorhexidine digluconate (CHX) biocide in Acinetobacter baumannii. In this study, a panel of reference strains and clinical isolates of Gram-negative bacteria, Gram-positive bacteria and yeasts were analyzed for susceptibility to CHX and benzalkonium chloride (BZK) and found to be tolerant to one or both biocides. The carbonyl cyanide m-chlorophenylhydrazine protonophore (CCCP) efflux pump inhibitor reduced the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CHX and BZK in the majority of strains. RV reduced dose-dependently MIC and MBC of CHX and BZK biocides when used as single agents or in combination in all analyzed strains, but not CHX MIC and MBC in Pseudomonas aeruginosa, Candida albicans, Klebsiella pneumoniae, Stenotrophomonas maltophilia and Burkholderia spp. strains. In conclusion, RV reverts tolerance and restores susceptibility to CHX and BZK in the majority of microorganisms responsible for HAI. These results indicates that the combination of RV, CHX and BZK may represent a useful strategy to maintain susceptibility to biocides in several nosocomial pathogens.

Inhibition of AdeB, AceI, and AmvA Efflux Pumps Restores Chlorhexidine and Benzalkonium Susceptibility in Acinetobacter baumannii ATCC 19606

The management of infections caused by Acinetobacter baumannii is hindered by its intrinsic tolerance to a wide variety of biocides. The aim of the study was to analyze the role of different A. baumannii efflux pumps (EPs) in tolerance to chlorhexidine (CHX) and benzalkonium (BZK) and identify non-toxic compounds, which can restore susceptibility to CHX and BZK in A. baumannii. A. baumannii ATCC 19606 strain was tolerant to both CHX and BZK with MIC and MBC value of 32 mg/L. CHX subMIC concentrations increased the expression of adeB and adeJ (RND superfamily), aceI (PACE family) and amvA (MFS superfamily) EP genes. The values of CHX MIC and MBC decreased by eightfold in ΔadeB and twofold in ΔamvA or ΔaceI mutants, respectively, while not affected in ΔadeJ mutant; EPs double and triple deletion mutants showed an additive effect on CHX MIC. CHX susceptibility was restored in double and triple deletion mutants with inactivation of adeB gene. BZK MIC was decreased by fourfold in ΔadeB mutant, and twofold in ΔamvA and ΔaceI mutants, respectively; EPs double and triple deletion mutants showed an additive effect on BZK MIC. BZK susceptibility was recovered in ΔadeB ΔaceI ΔadeJ and ΔamvA ΔadeB ΔadeJ triple mutants. The structural comparison of AdeB and AdeJ protomers showed a more negatively charged entrance binding site and F-loop in AdeB, which may favor the transport of CHX. The carbonyl cyanide m-chlorophenylhydrazine protonophore (CCCP) EP inhibitor reduced dose-dependently CHX MIC in A. baumannii ATCC 19606 and in ΔadeJ, ΔaceI, or ΔamvA mutants, but not in ΔadeB mutant. Either piperine (PIP) or resveratrol (RV) at non-toxic concentrations inhibited CHX MIC in A. baumannii ATCC 19606 parental strain and EPs gene deletion mutants, and CHX-induced EP gene expression. Also, RV inhibited BZK MIC and EP genes expression in A. baumannii ATCC 19606 parental strain and EPs mutants. These results demonstrate that tolerance to CHX and BZK in A. baumannii is mediated by the activation of AdeB, AceI and AmvA EPs, AdeB playing a major role. Importantly, inhibition of EP genes expression by RV restores CHX and BZK susceptibility in A. baumannii.

Do isolates from pharyngeal and rectal swabs match blood culture bacterial pathogens in septic VLBW infants? A pilot, cross-sectional study

Serial body site swabbing is used to monitor horizontal spread of aggressive bacterial species in the neonatal intensive care unit (NICU). Since colonization/carriage is thought to precede systemic infection, one might expect to retrieve colonizing pathogens from blood cultures. This hypothesis, however, has not been fully investigated in very low birth weight (VLBW) infants that are at high sepsis' risk. The primary outcome was, in a population of VLBW infants with late-onset sepsis, the matching between blood culture results and pathogens isolated from rectal and nose/pharyngeal surveillance swabs in the preceding 2 weeks. The secondary outcomes were the site of swabbing and time interval from colonization to blood culture positivity. Out of 333 VLBW neonates, 80 (24%) were diagnosed with bacterial sepsis. In 46 (57%) neonates, the blood culture showed the same pathogen species cultured from a swab. Of these, 30 were isolated from infants with both body sites colonized with an average time interval of 3.5 days; 2/16 were isolated from rectal swabs and 14 /16 from nose/pharyngeal samples.Conclusion: Our data show a fair correspondence between bacteria colonizing the nasopharynx and/or the rectum and pathogens later isolated from blood cultures. This association depends on the swabbing site, number of sites, and pathogen species. Although these data constitute valuable results, they are not sufficient for providing the sole base of a thoughtful clinical decision. What is Known: • Body site's colonization may precede systemic infection. • Little is known on this mechanism in VLBW infants that are at higher sepsis' risk. What is New: •Colonizing bacteria partially correspond to pathogens of blood cultures in VLBW infants with sepsis. • Correspondence depends on swabbing site, number of sites, and pathogen species.

Molecular epidemiology of carbapenem-resistant Acinetobacter baumannii in Italy

Conclusions

Our data reinforces the need to monitor the molecular epidemiology of CR A. baumannii and its associated antimicrobial resistance genes at national level.

Background

Carbapenem-resistant (CR) Acinetobacter baumannii has been increasingly recognized as a major cause of health care-associated infections in critically ill patients and hospital outbreaks.

Results

CR A. baumannii isolates assigned to international clonal lineage II (ICL II) and to ST78 clonal lineages were responsible for several epidemics in Italian hospitals during 2002-2018. Molecular analysis of carbapenem resistance showed the presence of OXA-58 CHDL in A. baumannii isolates assigned to ICL II and ST78 clonal lineage, which was replaced by OXA-23 CHDL in A. baumannii isolates assigned to ICL II since 2007 in several hospitals. CR A. baumannii was mainly responsible for respiratory tract infections and at a lesser extent for sepsis in intensive care unit patients.

Methods

A narrative review of literature was conducted, searching PubMed database for articles on CR Acinetobacter spp. isolates from Italy published between January 2010 and December 2019.

Risk factors for Candida parapsilosis bloodstream infection in a neonatal intensive care unit: a case-control study

Background

Candida parapsilosis is increasingly responsible for invasive candidiasis in neonates. This study investigates phenotypic and genotypic features of C. parapsilosis microbial isolates and underlying clinical conditions associated with acquisition of C. parapsilosis in a neonatal intensive care unit (NICU) in Italy.

Methods

Identification of C. parapsilosis was performed by VITEK® 2 and MALDI TOF and confirmed by analysis of internal transcribed spacer ribosomal DNA sequences. Genotyping was performed by PCR fingerprinting. Antifungal susceptibility of strains was evaluated by microdilution. A case-control study was designed to identify risk factors for C. parapsilosis bloodstream infection.

Results

During the study period (April 2009- April 2012), C. parapsilosis was responsible for 6 umbilical catheter and 11 central catheter-associated bloodstream infection in 17 neonates in the NICU. Molecular typing identified identical fingerprinting profile in all C. parapsilosis isolates from neonates. Fifteen of 17 C. parapsilosis isolates were susceptible to all antifungal drugs, two isolates were resistant to fluconazole and intermediate susceptible to itraconazole. Low birthweight, gestational age and time to exposure to assisted ventilation were risk factors for C. parapsilosis infection in neonates in the NICU at univariate and multivariate analysis.

Conclusion

C. parapsilosis bloodstream infections in the NICU were caused by a single epidemic clone. Low birthweight, gestational age and time to exposure to invasive devices, with predominance of assisted ventilation, were the clinical conditions associated with C. parapsilosis bloodstream infection in the NICU.

Electronic supplementary material

The online version of this article (doi:10.1186/s13052-017-0332-5) contains supplementary material, which is available to authorized users.

Molecular epidemiology of carbapenem resistant Enterobacteriaceae in Valle d'Aosta region, Italy, shows the emergence of KPC-2 producing Klebsiella pneumoniae clonal complex 101 (ST101 and ST1789)

BACKGROUND

The spread of carbapenem resistant Enterobacteriaceae (CRE) is an emerging clinical problem, of great relevance in Europe and worldwide. The aim of this study was the molecular epidemiology of CRE isolates in Valle d'Aosta region, Italy, and the mechanism of carbapenem resistance.

RESULTS

Sixty consecutive CRE samples were isolated from 52 hospital inpatients and/or outpatients from November 2013 to August 2014. Genotyping of microbial isolates was done by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST), carbapenemases were identified by PCR and sequencing. Carbapenem resistance gene transfer was performed by filter mating, plasmids from parental and transconjugant strains were assigned to incompatibility groups by PCR-based replicon typing. Molecular characterization of CRE isolates assigned 25 Klebsiella pneumoniae isolates to PFGE types A1-A5 and sequencing type (ST) 101, 17 K. pneumoniae isolates to PFGE type A and ST1789 (a single locus variant of ST101), 7 K. pneumoniae isolates to PFGE types B or C and ST512, 2 K. pneumoniae isolates to PFGE type D and ST405, and 5 Escherichia coli isolates to PFGE type a and ST131. All K. pneumoniae ST101 and ST1789 isolates were extended-spectrum beta-lactamase (ESBL) producers and carried bla CTX-M-1 group gene; 4 K. pneumoniae ST101 isolates were resistant to colistin. Molecular analysis of beta-lactamase genes identified bla KPC-2 and bla CTX-M-group 1 into conjugative plasmid/s assigned to IncFII incompatibility group in ST101 and ST1789 K. pneumoniae isolates, bla KPC-3 into conjugative plasmid/s assigned to IncF incompatibility group in ST512 and ST405 K. pneumoniae isolates, bla VIM-1 into conjugative plasmid/s assigned to IncN incompatibility group in ST131 E. coli isolates.

CONCLUSIONS

The spread of CRE in Valle d'Aosta region was caused by the selection of KPC-2 producing K. pneumoniae ST101 and ST1789 epidemic clones belonging to clonal complex 101, KPC-3 producing K. pneumoniae epidemic clones assigned to ST512 and ST405, and VIM-1 producing E.coli ST131 epidemic clone. Carbapenem resistance, along with bla KPC-2, bla KPC-3 and bla VIM-1 carbapenemase genes, was transferred by conjugative plasmids assigned to IncFII, IncF, and IncN incompatibility groups, respectively, in filter mating experiments. The emergence of colistin resistance was observed in KPC-2 producing K. pneumoniae ST101 isolates.

Clonal spread and patient risk factors for acquisition of extensively drug-resistant Acinetobacter baumannii in a neonatal intensive care unit in Italy

AIM

To report an outbreak of extensively drug-resistant (XDR) Acinetobacter baumannii in the neonatal intensive care unit (NICU) of an Italian university hospital. Patient risk profiles for acquisition of A. baumannii and measures used to control the outbreak are described.

METHODS

Antibiotic susceptibility of strains was evaluated by microdilution. Genotyping was performed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Carbapenemase genes were analysed by polymerase chain reaction and DNA sequencing. A case-control study was designed to identify risk factors for acquisition of A. baumannii.

FINDINGS

A. baumannii was isolated from 22 neonates, six of whom were infected. One major PFGE type was identified, assigned to sequence type (ST) 2, corresponding to International Clone II; this was indistinguishable from isolates from the adult ICU in the same hospital. A. baumannii isolates were resistant to aminoglycosides, quinolones and classes of β-lactam antibiotics, but were susceptible to tigecycline and colistin. Carbapenem resistance was associated with the presence of transposon Tn2006 carrying the bla(OxA-23) gene. Length of NICU stay, length of exposure to A. baumannii, gestational age, use of invasive devices and length of exposure to invasive devices were significantly associated with acquisition of A. baumannii on univariate analysis, while length of exposure to central venous catheters and assisted ventilation were the only independent risk factors after multi-variate analysis.

CONCLUSIONS

This XDR A. baumannii outbreak in an NICU was probably caused by intrahospital transfer of bacteria via a colonized neonate whose mother was admitted to the adult ICU. Strengthened infection control measures were necessary to control the outbreak.

Automated cleaning of fan coil units with a natural detergent-disinfectant product

Background

Air conditioning systems represent one important source of microbial pollutants for indoor air. In the past few years, numerous strategies have been conceived to reduce the contamination of air conditioners, mainly in hospital settings. The biocidal detergent BATT2 represents a natural product obtained through extraction from brown seaweeds, that has been tested previously on multidrug-resistant microorganisms.

Methods

BATT2 has been utilized for the disinfection of fan coil units from four air conditioning systems located in hospital environments with a mean degree of risk. Samples were collected from the air supplied by the conditioning systems and from the surfaces of fan coil units, before and after sanitization procedures. Total microbial counts at 37°C and 22°C and mycotic count at 32°C were evaluated. Staphylococci and Pseudomonas aeruginosa were also detected on surfaces samples.

Results

The biodetergent was able to reduce up 50% of the microbial pollution of fan coil units surfaces and air supplied by the air conditioners.

Conclusions

BATT2 could be considered for cleaning/disinfection of air conditioning systems, that should be performed on the basis of accurate and verifiable sanitization protocols.

Microbiological evaluation of the efficacy of two new biodetergents on multidrug-resistant nosocomial pathogens

BACKGROUND

In the last few years, several outbreaks of nosocomial infections caused by multidrug-resistant pathogenic agents have been observed, and various biocides products were developed in order to control this phenomenon. We investigated the efficacy of two natural biodetergents composed of plants and kelps extracts, BATT1 and BATT2, against multidrug-resistant strains.

METHODS

In-vitro antibacterial efficacy of BATT1 and BATT2 against nosocomial multidrug-resistant isolates was assessed using a suspension-inhibition test, with and without bovine serum albumin (BSA). The test was also carried out on glass surfaces with and without BSA.

RESULTS

In vitro tests with both biocidal disinfectants at 25% concentration demonstrated an overall drop in bacterial, mould and yeast counts after 10 min of contact with or without organic substances. For Pseudomonas aeruginosa, it was necessary to use undiluted disinfectants with and without an organic substance. The same results were obtained in tests carried out on glass surfaces for all strains.

CONCLUSIONS

The natural products BATT1 and BATT2 behave like good biocides even in presence of organic substances. The use of both disinfectants may be beneficial for reducing hospital-acquired pathogens that are not susceptible to disinfectants.However, it has to be stressed that all these experiments were carried out in vitro and they still require validation from use in clinical practice.

Risk factors for extended-spectrum beta-lactamase-producing Serratia marcescens and Klebsiella pneumoniae acquisition in a neonatal intensive care unit

We investigated the molecular epidemiology of gentamicin-resistant, extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae and Serratia marcescens, and risk factors associated with their acquisition in a neonatal intensive care unit (NICU) of a university hospital in Italy. During the study period (April-November 2004), S. marcescens was responsible for six infections and 31 colonisations, while K. pneumoniae was responsible for six infections and 103 colonisations. Concurrent isolation of both organisms occurred in 24 neonates. Molecular typing identified one major pulsed-field gel electrophoresis pattern each for S. marcescens and K. pneumoniae strains isolated during the study period. An 80 kb plasmid containing bla(SHV-12), bla(TEM-1) and aac(6')-Ib genes, isolated from both S. marcescens and K. pneumoniae strains, and showing identical restriction profiles, transferred resistance to third-generation cephalosporins to a previously susceptible Escherichia coli host. Birthweight, gestational age and use of invasive devices were significantly associated with S. marcescens and K. pneumoniae acquisition on univariate analysis, while empiric antimicrobial treatment with ampicillin and gentamicin, and duration of hospital stay, proved to be the only independent risk factors. In conclusion, conjugal plasmid transfer and empiric antimicrobial therapy with ampicillin and gentamicin might have contributed to the selection and spread of gentamicin-resistant ESBL-producing Enterobacteriaceae in the NICU.

Assessment of the efficacy of Umonium38 on multidrug-resistant nosocomial pathogens

INTRODUCTION

We investigated the efficacy of a biocide Umonium38 on multidrug-resistant strains by comparison with a chloride derivative (Decs).

METHODS

In vitro susceptibility tests were performed by agar diffusion disk and results were interpreted according to Clinical and Laboratory Standards Institute (CLSI). In vitro antibacterial efficacy of Umonium38 and Decs over selected strains was evaluated according to European Standards protocol with or without organic substance.

RESULTS

In vitro tests with Umoniumnr at 2.5% concentration demonstrated an overall drop in microbial and yeast charges after 5 min. contact without organic substance. The same results were obtained in presence of organic substance. In vitro tests with chloride derivative at 5% without organic substance also resulted in overall drop in bacterial and mycotic charges. Conversely, in presence of organic substance, the hypochlorite reduced the initial 10 UFC/ml to 10 UFC/ml for all bacterial strains with a decrease of 4 log except for Enterococcus faecalis and Candida albicans whose reduction was 2 and 1 log units respectively.

DISCUSSION

The organic substance in water requires large use of oxidising disinfectants (chloride, ozone) implying in the need for higher-than-standard concentrations. The disinfecting effect of chloride is only visible when the "requirement" of organic substance has been met. By contrast, Umonium38 behaves like a powerful biocide even in presence of organic substance, as it is not "consumed" by possible organic residues.

CONCLUSIONS

Umonium38 resulted beneficial and effective. It is to be stressed, however, that all these experiments were in vitro tests and still requires validation from a correct use of clinical practice.

Molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii in a university hospital in Italy

This study investigated the molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii that occurred between June 2003 and June 2004 in a tertiary-care hospital in Naples, Italy. A. baumannii was isolated from 74 patients, of whom 38 were infected and 36 were colonised. Thirty-three patients had ventilator-associated pneumonia, three had hospital-acquired pneumonia, and two had sepsis. Genotypic analysis of 45 available A. baumannii isolates revealed two distinct pulsed-field gel electrophoresis (PFGE) patterns. Of these, PFGE pattern 1 was represented by isolates from 44 patients and was identical to that of an epidemic A. baumannii clone isolated in another hospital of Naples during 2002. All A. baumannii isolates of PFGE type 1 showed identical multiresistant antibiotypes, characterised by resistance to all antimicrobial agents tested, including carbapenems, with the exception of colistin. In these isolates, inhibition of OXA enzymes by 200 mM NaCl reduced the imipenem MIC by up to four-fold. Molecular analysis of antimicrobial resistance genes showed that all A. baumannii isolates of PFGE type 1 harboured a class 1 integron containing the aacA4, orfX and bla(OXA-20) gene cassettes, an ampC gene and a bla(OXA-51)-like allele. Moreover, a bla(OXA-58)-like gene surrounded by the regulatory elements ISAba2 and ISAba3 was identified in a 30-kb plasmid from A. baumannii isolates of PFGE type 1, but not PFGE type 2. Thus, selection of a single A. baumannii clone producing an OXA-58-type carbapenem-hydrolysing oxacillinase was responsible for the increase in the number of A. baumannii infections that occurred in this hospital.

Molecular epidemiology of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit

OBJECTIVES

To investigate the molecular epidemiology of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in the neonatal intensive care unit of a university hospital in Italy.

METHODS

Antibiotic susceptibility was evaluated by disc diffusion and Etest. ESBLs were identified by isoelectric focusing, PCR and DNA sequencing analysis. Genotyping was performed by PFGE analysis. Conjugation was performed by broth mating.

RESULTS

Molecular typing of K. pneumoniae isolates identified three distinct PFGE patterns. Isolates of PFGE profile A were isolated during an epidemic in 1996, while isolates of PFGE profiles B and C were sequentially isolated from September 2002 to December 2004, when 233 colonizations and 19 infections by K. pneumoniae occurred. All K. pneumoniae strains of different PFGE types were identified as ESBL producers. DNA sequencing of amplified beta-lactamase genes identified a novel bla(TEM) ESBL (bla(TEM-136)) along with bla(SHV-1) in chromosomal and plasmid DNA from K. pneumoniae of PFGE type A, respectively, and bla(TEM-1) and bla(SHV-12) in plasmid DNA from K. pneumoniae of PFGE types B and C. Conjugation experiments demonstrated that resistance to third-generation cephalosporins, along with an approximately 80 kb plasmid containing bla(SHV-12) and bla(TEM-1), was transferred from K. pneumoniae epidemic strains of PFGE types B and C to a susceptible Escherichia coli host at a frequency of 4 x 10(-6) and 1 x 10(-6) cfu/recipient cell, respectively.

CONCLUSIONS

The selection of ESBL-producing clones and the transfer of the bla(SHV-12) ESBL gene between different clones were responsible for the spread of K. pneumoniae in the neonatal intensive care unit.

Molecular epidemiology of high-level aminoglycoside-resistant enterococci isolated from patients in a university hospital in southern Italy

OBJECTIVES

We evaluated the genetic and molecular basis of high-level resistance to gentamicin and amikacin in 91 clinical isolates of Enterococcus faecalis and Enterococcus faecium in a university hospital in southern Italy from 1987 to 2003.

METHODS

Antibiotic susceptibility was evaluated by disc diffusion and microdilution methods. Genotyping was performed by PFGE and dendrogram analysis. Aminoglycoside resistance genes were analysed by multiplex PCR. Aminoglycoside resistance gene transfer was performed by filter mating.

RESULTS

In our strain collection, 44% of E. faecalis and 52% of E. faecium were high-level-resistant to gentamicin. Fifty-two PFGE profiles were identified for E. faecalis and 15 for E. faecium. Although the majority of PFGE patterns were single isolates, four patterns (two for E. faecalis and two for E. faecium) were isolated each in 8 and 4, and 6 and 4 different patients, respectively. The aac(6')-Ie-aph(2'')-Ia gene was responsible for high-level resistance to gentamicin and amikacin in E. faecalis and E. faecium; the aph(2'')-Id gene responsible for resistance to gentamicin was also isolated in E. faecium; the aph(3')-IIIa and ant(4')-Ia genes responsible for resistance to amikacin were also isolated in E. faecalis and E. faecium. High-level resistance to gentamicin, along with the aac(6')-Ie-aph(2'')-Ia gene, was transferred at a frequency of about 10(-5) to 10(-8) per recipient cell in 14 of 17 E. faecalis and 3 of 4 E. faecium different genotypes.

CONCLUSIONS

The spread of the aac(6')-Ie-aph(2'')-Ia gene was responsible for high-level resistance to gentamicin and amikacin among enterococci isolated from patients in our geographical area.

Molecular epidemiology of sequential outbreaks of Acinetobacter baumannii in an intensive care unit shows the emergence of carbapenem resistance

The molecular epidemiology of multidrug-resistant Acinetobacter baumannii was investigated in the medical-surgical intensive care unit (ICU) of a university hospital in Italy during two window periods in which two sequential A. baumannii epidemics occurred. Genotype analysis by pulsed-field gel electrophoresis (PFGE) of A. baumannii isolates from 131 patients identified nine distinct PFGE patterns. Of these, PFGE clones B and I predominated and occurred sequentially during the two epidemics. A. baumannii epidemic clones showed a multidrug-resistant antibiotype, being clone B resistant to all antimicrobials tested except the carbapenems and clone I resistant to all antimicrobials except ampicillin-sulbactam and gentamicin. Type 1 integrons of 2.5 and 2.2 kb were amplified from the chromosomal DNA of epidemic PFGE clones B and I, respectively, but not from the chromosomal DNA of the nonepidemic clones. Nucleotide analysis of clone B integron identified four gene cassettes: aacC1, which confers resistance to gentamicin; two open reading frames (ORFs) coding for unknown products; and aadA1a, which confers resistance to spectinomycin and streptomycin. The integron of clone I contained three gene cassettes: aacA4, which confers resistance to amikacin, netilmicin, and tobramycin; an unknown ORF; and bla(OXA-20), which codes for a class D beta-lactamase that confers resistance to amoxicillin, ticarcillin, oxacillin, and cloxacillin. Also, the bla(IMP) allele was amplified from chromosomal DNA of A. baumannii strains of PFGE type I. Class 1 integrons carrying antimicrobial resistance genes and bla(IMP) allele in A. baumannii epidemic strains correlated with the high use rates of broad-spectrum cephalosporins, carbapenems, and aminoglycosides in the ICU during the study period.

A nosocomial outbreak of Serratia marcescens producing inducible Amp C-type beta-lactamase enzyme and carrying antimicrobial resistance genes within a class 1 integron

We investigated an outbreak of Serratia marcescens in the adult intensive care unit of the University Hospital of Napoli. The outbreak involved 13 cases of infection by S. marcescens over a nine-month period and was caused by a single pulsed-field gel electrophoresis clone. The epidemic strain was multiply antibiotic resistant, producing an inducible Amp C-type beta-lactamase enzyme and carrying the trimethoprim-resistance gene and the adenyltransferase gene, which confers resistance to streptomycin and spectinomycin, within a class 1 integron. Antimicrobial therapy with beta-lactams was associated with S. marcescens acquisition in the intensive care unit.

Molecular epidemiology of Stenotrophomonas maltophilia in a university hospital

The aim of this investigation was to study the molecular epidemiology of Stenotrophomonas maltophilia in a university hospital in Italy. Sixty-one clinical isolates were collected from 43 patients during a two-year period. The majority of specimens were from the respiratory tract (41 of 43) of patients in the adult intensive care unit (ICU) (19 of 43) or cystic fibrosis (CF) patients (13 of 43). Genotypic analysis by pulsed-field gel electrophoresis (PFGE) of clinical isolates identified 31 different PFGE patterns. Although most patients were infected or colonized by different S. maltophilia clones, clones with identical genotype were isolated in patients from ICU, where two separate outbreaks were identified. Antimicrobial susceptibility identified a multi-resistant phenotype in all S. maltophilia PFGE clones. The majority of PFGE clones identified (six of seven clones from patients in the ICU) were susceptible to fluoroquinolones. Mechanical ventilation was associated with S. maltophilia acquisition in the ICU.

High-dose intravenous corticosteroid therapy for Graves' ophthalmopathy

In order to compare oral and high-dose iv corticosteroid therapy for Graves' disease, 25 patients with Graves' ophthalmopathy were treated with two weekly iv injections of 1 g of methylprednisolone diluted in 250-500 ml of physiological solution for 6 weeks, and were compared to a group of 26 patients treated with oral prednisone at a dose of 60-80 mg/day progressively reduced every 2 weeks for a total duration of 4-6 months. The efficacy of treatment was evaluated using the ophthalmopathy index score. Patients were followed at 3, 6, 12 months, and afterwards yearly. All patients showed a significant improvement in signs and symptoms of orbital inflammation and a slight improvement in proptosis and diplopia. Relevant side-effects were reported from patients receiving oral therapy, but no significant side-effects were observed in patients treated with high iv doses; a few cases presented with gastric pain (highly sensitive to aluminium oxide or ranitidine), while most of the patients referred to cutaneous rashes and a metal taste that disappeared some hours after the infusion. Improvements observed after treatment have been stable in both groups. In conclusion, in addition to a lower incidence of side-effects compared to the classic oral therapy, the high-dose iv steroid therapy provides efficient and stable improvement in Graves' ophthalmopathy.