Outbreak of extended-spectrum beta-lactamase producing Serratia marcescens in an intensive care unit

First Italian outbreak of VIM-producing Serratia marcescens in an adult polyvalent intensive care unit, August-October 2018: A case report and literature review

BACKGROUND

Carbapenem-resistant Enterobacteriaceae has become a significant public health concern as hospital outbreaks are now being frequently reported and these organisms are becoming difficult to treat with the available antibiotics.

CASE SUMMARY

An outbreak of VIM-producing Serratia marcescens occurred over a period of 11 wk (August, 1 to October, 18) in patients admitted to the adult polyvalent intensive care unit of the University of Campania “Luigi Vanvitelli” located in Naples. Four episodes occurred in three patients (two patients infected, and one patient colonized). All the strains revealed the production of VIM.

CONCLUSION

After three decades of carbapenem antibiotics use, the emergence of carbapenem-resistance in Enterobacteriaceae has become a significant concern and a stricter control to preserve its clinical application is mandatory. This is, to our knowledge, the first outbreak of VIM-producing Serratia marcescens in Europe. Surveillance policies must be implemented to avoid future outbreaks.

Detection of CTX-M-15 beta-lactamases in Enterobacteriaceae causing hospital- and community-acquired urinary tract infections as early as 2004, in Dar es Salaam, Tanzania

Background

The spread of Extended Spectrum β-lactamases (ESBLs) among Enterobacteriaceae and other Gram-Negative pathogens in the community and hospitals represents a major challenge to combat infections. We conducted a study to assess the prevalence and genetic makeup of ESBL-type resistance in bacterial isolates causing community- and hospital-acquired urinary tract infections.

Methods

A total of 172 isolates of Enterobacteriaceae were collected in Dar es Salaam, Tanzania, from patients who met criteria of community and hospital-acquired urinary tract infections. We used E-test ESBL strips to test for ESBL-phenotype and PCR and sequencing for detection of ESBL genes.

Results

Overall 23.8% (41/172) of all isolates were ESBL-producers. ESBL-producers were more frequently isolated from hospital-acquired infections (32%, 27/84 than from community-acquired infections (16%, 14/88, p < 0.05). ESBL-producers showed high rate of resistance to ciprofloxacin (85.5%), doxycycline (90.2%), gentamicin (80.5%), nalidixic acid (84.5%), and trimethoprim-sulfamethoxazole (85.4%). Furthermore, 95% of ESBL-producers were multi-drug resistant compared to 69% of non-ESBL-producers (p < 0.05). The distribution of ESBL genes were as follows: 29/32 (90.6%) bla_CTX-M-15, two bla_SHV-12, and one had both bla_CTX-M-15 and bla_SHV-12. Of 29 isolates carrying bla_CTX-M-15, 69% (20/29) and 31% (9/29) were hospital and community, respectively. Bla_SHV-12 genotypes were only detected in hospital-acquired infections.

Conclusion

bla_CTX-M-15 is a predominant gene conferring ESBL-production in Enterobacteriaceae causing both hospital- and community-acquired infections in Tanzania.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2395-8) contains supplementary material, which is available to authorized users.

Spread in an Italian hospital of a clonal Acinetobacter baumannii strain producing the TEM-92 extended-spectrum beta-lactamase

Clinical isolates of Acinetobacter baumannii (n = 470) were collected during a 7-year period and investigated for the genetic determinants of resistance to expanded-spectrum beta-lactams. Thirty-one isolates produced the TEM-92 extended-spectrum beta-lactamase (ESBL) and were clonally related. This is the first report of A. baumannii producing a TEM-type ESBL.

Three-year follow-up of an outbreak of Serratia marcescens bacteriuria in a neurosurgical intensive care unit

We report on the investigations and interventions conducted to contain an extended outbreak of Serratia marcescens bacteriuria that lasted for years in a neurosurgical intensive care unit (NSICU). A case-control study was performed to identify the risk factors for S. marcescens acquisition in urine. In case patients, urine sampling for tests and central venous catheterization were performed more frequently before the isolation of S. marcescens. Case patients were more frequently prescribed third-generation cephalosporins. Adherence to hand antisepsis was encouraged through in-service educational meetings and infection control measures, especially concerning the manipulation of indwelling urinary catheters, were intensified. The outbreak persisted despite the reinforcement of infection control measures. However, no patient has newly acquired the organism in the NSICU since December 2004. Multiple factors, including inadequate infection control practices and inappropriate antimicrobial usage, possibly contributed to the persistence of this S. marcescens outbreak. Healthcare workers should consistently follow infection control policies to ensure quality care.

Dissemination of CTX-M-type extended-spectrum beta-lactamase genes to unusual hosts

A Citrobacter amalonaticus and a Morganella morganii producing the CTX-M-1 extended-spectrum beta-lactamase (ESBL) were isolated from an area where this enzyme is now widespread in Escherichia coli. This is the first report of CTX-M-1 in the former species. In both cases the ESBL determinant was possibly acquired by these unusual hosts in vivo, after coinfection with E. coli strains carrying conjugative plasmids encoding CTX-M-1.

Multifocal detection of multidrug-resistant Pseudomonas aeruginosa producing the PER-1 extended-spectrum beta-lactamase in Northern Italy

Forty-four nonreplicate clinical isolates of Pseudomonas aeruginosa that were resistant to extended-spectrum cephalosporins (ceftazidime and cefepime) and aztreonam, that putatively produced an acquired extended- spectrum beta-lactamase (ESBL), according to the results of a double-disk synergy test, and that had been involved in nosocomial outbreaks were obtained from six different hospitals in northern Italy and screened for the presence of bla(PER) ESBL determinants. Twenty isolates, associated with nine independent outbreaks that occurred in five hospitals in the Milan area and its surroundings during 1995-2000, were found to carry an acquired bla(PER-1) gene. PER-1 producers representative of the nine outbreaks exhibited a multidrug resistance (MDR) phenotype, including resistance to extended-spectrum cephalosporins, aztreonam, meropenem, aminoglycosides, and in most cases, imipenem and ciprofloxacin. An analysis of macrorestriction profiles of their genomic DNAs by pulsed-field gel electrophoresis revealed an overall clonal diversity of the PER-1 producers, although interhospital clonal spread was also observed. The bla(PER-1) gene was not transferable and appeared to be chromosomally located. An analysis of the EcoRI and EcoRV restriction fragment length polymorphisms of the bla(PER-1) locus revealed identical patterns for all isolates, and the characterization of a 1.9-kb region containing bla(PER-1) revealed a conserved structure in representatives of the various clonal lineages. The present findings indicate that MDR P. aeruginosa clones producing the PER-1 ESBL are endemic to this area of northern Italy, where they have been circulating since the mid-1990s and have been associated with several nosocomial outbreaks.

Extended epidemic of nosocomial urinary tract infections caused by Serratia marcescens

In recent years a significant increase in the incidence of Serratia marcescens infections was noted at the Chang Gung Memorial Hospital, Taoyuan, Taiwan. A review of laboratory (1991 to 2002) and infection control (1995 to 2002) records showed the possibility of an extended epidemic of nosocomial urinary tract infections (UTIs) caused by S. marcescens. Therefore, in 1998 and 1999, 87 isolates were collected from patients with such infections and examined and another 51 isolates were collected in 2001 and 2002. The patients were mostly elderly or the infections were associated with the use of several invasive devices. S. marcescens was usually the only pathogen found in urine cultures in our study. Neither prior infections nor disseminated infections with the organism were observed in these patients. Resistance to most antibiotics except imipenem was noted. Two genotyping methods, pulsed-field gel electrophoresis and infrequent-restriction-site PCR, were used to examine the isolates. A total of 12 genotypes were identified, and 2 predominant genotypes were found in 72 (82.8%) of the 87 isolates derived from all over the hospital. However, 63.9% of the isolates of the two genotypes were from neurology wards. A subsequent intervention by infection control personnel reduced the infection rate greatly. The number and proportion of the two predominant genotypes were significantly reduced among the 51 isolates collected in 2001 and 2002. Thus, a chronic and long-lasting epidemic of nosocomial UTIs caused by S. marcescens was identified and a successful intervention was carried out. Both a cautious review of laboratory and infection control data and an efficient genotyping system are necessary to identify such a cryptic epidemic and further contribute to the quality of patient care.

Multiple CTX-M-type extended-spectrum beta-lactamases in nosocomial isolates of Enterobacteriaceae from a hospital in northern Italy

Twelve isolates of Enterobacteriaceae (1 of Klebsiella pneumoniae, 8 of Escherichia coli, 1 of Proteus mirabilis, and 2 of Proteus vulgaris) classified as extended-spectrum beta-lactamase (ESBL) producers according to the ESBL screen flow application of the BD-Phoenix automatic system and for which the cefotaxime MICs were higher than those of ceftazidime were collected between January 2001 and July 2002 at the Laboratory of Clinical Microbiology of the San Matteo University Hospital of Pavia (northern Italy). By PCR and sequencing, a CTX-M-type determinant was detected in six isolates, including three of E. coli (carrying bla(CTX-M-1)), two of P. vulgaris (carrying bla(CTX-M-2)), and one of K. pneumoniae (carrying bla(CTX-M-15)). The three CTX-M-1-producing E. coli isolates were from different wards, and genotyping by pulsed-field gel electrophoresis (PFGE) revealed that they were clonally unrelated to each other. The two CTX-M-2-producing P. vulgaris isolates were from the same ward (although isolated several months apart), and PFGE analysis revealed probable clonal relatedness. The bla(CTX-M-1) and bla(CTX-M-2) determinants were transferable to E. coli by conjugation, while conjugative transfer of the bla(CTX-M-15) determinant from K. pneumoniae was not detectable. Present findings indicate that CTX-M enzymes of various types are present also in Italy and underscore that different CTX-M determinants can be found in a single hospital and can show different dissemination patterns. This is also the first report of CTX-M-2 in P. vulgaris.

Emerging extended-spectrum beta-lactamases in Proteus mirabilis

Beta-lactamase production was detected in 147 (52%) of 282 consecutive nonduplicate Proteus mirabilis isolates obtained over a 1-year period from the S. Matteo Hospital of Pavia (northern Italy). Seventy isolates (48% of the beta-lactamase producers) were found to produce extended-spectrum beta-lactamases (ESBLs), identified as PER-1 (first report in this species) and TEM-52 in 52 and 18 isolates, respectively. Analysis of clonal diversity of the ESBL producers suggested different spreading patterns for the two ESBL determinants.

Building communication networks: international network for the study and prevention of emerging antimicrobial resistance

The global nature of antimicrobial resistance and the failure to control the emergence of resistant organisms demand the implementation of a global surveillance program involving both developed and developing countries. Because of the urgent need for infection control interventions and for rapid distribution of information about emerging organisms, we initiated the International Network for the Study and Prevention of Emerging Antimicrobial Resistance (INSPEAR). Its main objectives are to serve as an early warning system for emerging antimicrobial-drug resistant pathogens, to facilitate rapid distribution of information about emerging multidrug-resistant pathogens to hospitals and public health authorities worldwide, and to serve as a model for the development and implementation of infection control interventions.

Repeated epidemics caused by extended-spectrum beta-lactamase-producing Serratia marcescens strains

An outbreak of Serratia marcescens involving 42 patients admitted to the general intensive care unit of the Hospital of Varese, Italy, occurred from March 1994 to August 1995. The causative strains were resistant to oxyimino-cephalosporins and monobactams due to their production of an extended-spectrum beta-lactamase. Another outbreak caused by Serratia marcescens strains had occurred in the same unit a few months earlier, from February to October 1993, with the strains involved producing a novel TEM-derived extended-spectrum beta-lactamase. In order to verify whether there were any relationships between isolates from the two epidemics, the strains and their enzymes were characterized. Biochemical data and gene amplification experiments showed that the isolates of the second outbreak harbored a non-conjugative plasmid of approximately 48 kb, codifying for the production of an SHV-derived extended-spectrum beta-lactamase with pI 8.2. Restriction fragment length polymorphism analysis of total genomic DNA by pulsed-field gel electrophoresis of Serratia marcescens isolates unambiguously identified two different bacterial clones responsible for the two epidemics. Epidemiological and microbiological investigations demonstrated the long persistence of Serratia marcescens strains and their circulation in other hospital wards, thus suggesting their possible role as a long-term reservoir for further epidemic spread.

Characterization of a new TEM-derived beta-lactamase produced in a Serratia marcescens strain

A natural TEM variant beta-lactamase was isolated from an epidemic strain of Serratia marcescens. Nucleotide gene sequencing revealed multiple point mutations located in the 42-to-44 tripeptide and positions 145 to 146, 178, and 238. In addition, a glutamic acid 212 deletion was also found. The purified enzyme was studied from a kinetic point of view, revealing the highest catalytic efficiency (k[cat]/Km) values for ceftazidime and aztreonam compared with the TEM-1 prototype enzyme. The in vitro resistance correlated with kinetic parameters, and the enzyme also mediated resistance to some penicillins and an ampicillin-clavulanic acid combination. The mutational and kinetic changes are discussed in relation to the three-dimensional crystallographic structure of the wild-type TEM-1 enzyme.

Detection of SHV-5 extended-spectrum beta-lactamase in Klebsiella pneumoniae strains isolated in Italy

Thirty-five Klebsiella pneumoniae strains isolated during 1993-1994 in intensive care units of a large Italian hospital were examined for the presence of extended-spectrum beta-lactamases. Five strains showed a high level of simultaneous resistance to beta-lactam agents, including ceftazidime and aztreonam, conferred by a large (130 kb) self-transferable plasmid (in 4 of 5 strains). Isoelectrofocusing and hybridisation studies suggest that these enzymes can be identified as SHV-5 extended-spectrum beta-lactamases. Pulsed-field get electrophoresis analysis showed three different genomic fingerprinting profiles, while plasmid restriction enzyme digestion revealed three different patterns, demonstrating that the diffusion of SHV-5 beta-lactamase is not the result of a single strain or plasmid dissemination.

Superlytic hemolysin mutants of Serratia marcescens

Hemolysis by Serratia marcescens is caused by two proteins, ShlA and ShlB. ShlA is the hemolysin proper, and ShlB transports ShlA through the outer membrane, whereby ShlA is converted into a hemolysin. Superhemolytic ShlA derivatives that displayed 7- to 20-fold higher activities than wild-type ShlA were isolated. ShlA80 carried the single amino acid replacement of G to D at position 326 (G326D), ShlA87 carried S386N, and ShlA80III carried G326D and N236D. Superhemolysis was attributed to the greater stability of the mutant ShlA derivatives because they aggregated less than the wild-type hemolysin, which lost activity within 3 min at 20 degrees C. In contrast to the highly hemolytic wild-type ShlA at 0 degrees C, the hyperlytic hemolysins were nonhemolytic at 0 degrees C, suggesting that the hyperlytic derivatives differed from wild-type ShlA in adsorption to and insertion into the erythrocyte membrane. However, the size of the pores formed at 20 degrees C by superhemolytic hemolysins could not be distinguished from that of wild-type ShlA. In addition to the N-terminal sequence up to residue 238, previously identified to be important for activation and secretion, sites 326 and 386 contribute to hemolysin activity since they are contained in regions that participate in hemolysin inactivation through aggregation.