EXCEED EXPECTATIONS: “Pathology that Adds Value” Emergence of carbapenem resistant Enterobacteriaceae in South Africa Introduction Treatment
A recent article in the Lancet highlighted the emergence of
Many NDM-1 producers remain susceptible only to colistin and
Enterobacteriaceae with resistance to carbapenems, conferred by
tigecycline. A few isolates, mostly E. coli, retain a degree of
New Delhi metallo-β-lactamase 1 (NDM-1). NDM-1 refers to a
susceptibility to antibiotics such as chloramphenicol, tetracycline,
transmissible genetic element encoding multiple resistance genes
fosfomycin, aminoglycosides and aztreonam. Combination
that was initially isolated from a strain of Klebsiella obtained from a
therapy is associated with improved outcome.
patient who acquired the organism in New Delhi, India.
Early identification of cases of NDM-1-related infections and of the
The authors identified numerous isolates with NDM-1 in India,
carriers is essential. NDM-1 susceptibility to carbapenems varies
Pakistan and the UK. Except for central and South America this
and ertapenem may be the most appropriate for detecting NDM-1
mechanism of resistance has now been identified worldwide.
NDM-1 was mostly found among Escherichia coli and Klebsiella
producers with low-level resistance to this group of antimicrobials. pneumoniae, which were highly resistant to all antibiotics except to
Laboratory diagnosis
tigecycline and colistin. These organisms also carry numerous
other antibiotic resistance genes including those mediating
Phenotypic identification is difficult and molecular-based
resistance to aminoglycosides, macrolides, sulphamethoxazole,
techniques such as PCR are the gold standard for identification of
quinolones and other beta-lactams. Accordingly, most strains
NDM-1 producers. PathCare will automatically screen all
present with a multi-drug resistant (MDR) phenotype and some
Enterobacteriaceae resistant to any of the carbapenems, for the
may even present with a pan-drug resistant (PDR) phenotype.
This mechanism of resistance has now also been confirmed in
Infection control and screening
South Africa and will present a significant therapeutic challenge to
Isolation precautions should be applied for all patients colonized or
infected with a NDM-1 organism. These patients should also be
Risk factors
cohorted and preferably treated by dedicated staff.
Active screening policies might have to be implemented via stool or
The type of infections associated with NDM-1 producers are mostly
rectal swab cultures. Current guidelines suggest screening of
hospital-acquired infections, however, indirect fecal-oral
patients who received medical care in India or Pakistan during the
transmission may be likely to play a major role in community
last 6 months, but prolonged hospitalization, patients who are
settings, via contaminated hands, food and water.
critically ill and exposed to invasive devices (e.g., ventilators or
central venous catheters) are also at risk and might have to be
Previous antimicrobial exposure, prolonged hospitalization,
included in screening procedures to detect NDM-1.
presence of invasive devices, and immunosuppression are all
Hospitals should also perform active surveillance cultures of
associated with the selection of NDM-1 resistance.
patients with epidemiologic links to persons from whom
Infections associated with NDM-1
carbapenem resistant Enterobacteriaceae have been recovered.
In such instances, infection prevention measures should be
Isolates of Enterobacteriaceae producing NDM-1 have caused a
vigorously reinforced, and surveillance cultures repeated weekly
range of infections, most commonly urinary tract infections, but also
septicaemia, pulmonary infections, peritonitis, soft tissue infections
LABORATORY UPDATE www.pathcare.co.za November 2011
atologie wat WaardeToevoeg” Verskyning van karbapenem-weerstandige Enterobacteriaceae in Suid-Afrika Inleiding Behandeling
'n Onlangse artikel in die Lancet vestig aandag op die verskyning
Talle NDM-1-produseerders bly vatbaar net vir kolistien en
van Enterobacteriaceae met weerstand teen karbapenems,
tigesiklien. Enkele isolate, veral E.coli, behou 'n mate van
verleen deur die Nieu-Delhi metallo-β-laktamase 1 (NDM-1).
gevoeligheid vir antibiotika soos chlooramfenikol, tetrasiklien,
NDM-1 verwys na 'n oordraagbare genetiese element wat vir
fosfomisien, aminoglikosiede en aztreonam. Kombinasieterapie
veelvuldige weerstandgenes kodeer en wat aanvanklik vanaf 'n
stam van Klebsiella van 'n pasiënt wat die organisme in Nieu-Delhi,
Vroeë identifikasie van NDM-1-verwante infeksies en van draers is
noodsaaklik. NDM-1-vatbaarheid vir karbapenems varieer en
Die skrywers het talle isolate met NDM-1 in Indië, Pakistan en die
ertapenem is moontlik die mees toepaslike vir die opsporing van
VK geïsoleer. Met die uitsondering van Sentraal- en Suid-Amerika
NDM-1-produseerders met laevlak weerstand teenoor hierdie
is hierdie meganisme van weerstand reeds wêreldwyd
geïdentifiseer. NDM-1 is meestal in Eschericia coli en Klebsiella pneumoniae gevind wat hoogs weerstandig teenoor alle
Laboratoriumdiagnose
antibiotika, met die uitsondering van tigesiklien en kolistien, was.
Identifikasie van fenotipe is moeilik en molekulêre tegnieke soos
Hierdie organisme dra ook vele ander weerstandsgenes teenoor
PKR is die goue standaard vir identifikasie van NDM-1-
antibiotika, insluitende dié wat weerstand teen aminoglikosiede,
produseerders. PathCare sal outomaties alle Enterobacteriaceae
makroliede, sulfametoksasool, kinoliene en ander beta-laktame
weerstandig teen enige van die karbapenems vir NDM-1 sif.
kodeer. Ooreenstemmend doen die stamme voor met 'n multi-
middelweerstandige (MDR) fenotipe en sommige mag selfs met 'n
Infeksiebeheer en sifting
panweerstandige (PDR) fenotipe voordoen.
Voorkomende isolering van alle gekoloniseerde of geïnfekteerde
Hierdie meganisme van weerstand is nou ook in Suid-Afrika
pasiënte met 'n NDM-1-organisme behoort plaas te vind. Hierdie
bevestig en sal 'n betekenisvolle terapeutiese uitdaging aan klinici
pasiënte behoort ook saam en verkieslik deur toegewyde
personeel behandel te word. Dit mag nodig wees om aktiewe sifting
via stoelgang- en rektale depper-kwekings te implimenteer.
Risikofaktore
Huidige riglyne stel sifting voor van pasiënte wat mediese sorg in
Die soort infeksies wat met NDM-1-produseerders geassosieer
Indië of Pakistan gedurende die voorafgaande 6 maande ontvang
word is meesal hospitaalverworwe infeksies, hoewel indirekte
het, maar verlengde hospitalisering, kritieke siek en pasiënte aan
fekale tot mondoordrag moontlik 'n belangrike rol in die
indringende toestelle blootgestel (bv. ventilators of sentrale
gemeenskapsomgewing via besmette hande, kos en water mag
veneuse kateters) is ook onderhewig aan risiko en mag moontlik by
siftingsprodures om NDM-1 op te spoor, ingesluit word.
Vorige antimikrobiese blootstelling, verlengde hospitalisering,
Hospitale behoort ook aktiewe oorsigskwekings van pasiënte te
inblywende toestelle, en immuun- onderdrukking hou almal met die
doen wat epidemiologiese kontak gehad het met persone van wie
seleksie van NDM-1-weerstand verband.
karbapenem-weerstandige Enterobacteriaceae geïsoleer is. In
sulke gevalle moet infeksievoorkomende maatreëls energiek
Infeksies met NDM-1 geassosieer
toegepas word, en oorsigskwekings weekliks gedoen word totdat
geen nuwe gevalle meer opgespoor word nie.
Isolate van Enterobacteriaceae wat NDM-1 produseer veroorsaak
'n verskeidenheid infeksies waarvan urineweginfeksies die mees
algemeen is, maar ook septisemie, longinfeksies, perotinitis, sagte
weefselinfeksies en toestelgeassosieerde infeksies word gesien. LABORATORIUM OPKNAPPER www.pathcare.co.za November 2011
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