Multidrug-Resistant Coagulase-Negative Staphylococci Isolated from Bloodstream in the uMgungundlovu District of KwaZulu-Natal Province in South Africa: Emerging Pathogens.

Jonathan Asante,Akebe Luther King Abia,Bakoena A Hetsa,Daniel G Amoako,Sabiha Y Essack,Linda A Bester

doi:10.3390/antibiotics10020198

Abstract

Coagulase-negative staphylococci (CoNS) are increasingly associated with nosocomial infections, especially among the immunocompromised and those with invasive medical devices, posing a significant concern. We report on clinical multidrug-resistant CoNS from the uMgungundlovu District, KwaZulu-Natal Province, South Africa, as emerging pathogens. One hundred and thirty presumptive CoNS were obtained from blood cultures. Culture, biochemical tests, and the Staphaurex™ Latex Agglutination Test were used for the initial identification of CoNS isolates; confirmation and speciation were undertaken by the VITEK 2 system. Susceptibilities of isolates against a panel of 20 antibiotics were determined using the Kirby-Bauer disk diffusion method, and the multiple antibiotic resistance (MAR) indices of the isolates were determined. The polymerase chain reaction (PCR) was used to amplify the mecA gene to confirm methicillin resistance. Overall, 89/130 presumptive CoNS isolates were confirmed as CoNS by the VITEK 2 system. Of these, 68 (76.4%) isolates were putatively methicillin-resistant by the phenotypic cefoxitin screen test and 63 (92.6%) were mecA positive. Staphylococcus epidermidis (19.1%), S. hominis ssp. hominis (15.7%), and S. haemolyticus (16.9%) were the most common CoNS species. Isolates showed high percentage resistance against penicillin (100.0%), erythromycin (74.2%), and azithromycin (74.2%) while displaying high susceptibilities to linezolid (95.5%), gentamicin (95.5%), and tigecycline (94.4%). Multidrug resistance (MDR) was observed in 76.4% of isolates. MAR index calculation revealed 71.9% of isolates with MAR index >0.2 and 20.2% >0.5. Isolates with the highest MAR indices (0.7 and 0.8) were recovered from the neonatal intensive care unit. Fifty-one MDR antibiograms were observed. The high prevalence of methicillin resistance and multidrug resistance in several species of CoNS necessitates surveillance of this emerging pathogen, currently considered a contaminant of microbial cultures.

Highlights

Staphylococci are classified as either coagulase-positive or coagulase-negative, depending on their ability to clot plasma that is facilitated by the enzyme coagulase [1].Coagulase-negative staphylococci (CoNS) are the most frequent colonizers of the skin and mucous membranes and the most frequently isolated organisms in microbiology laboratories [2]
This study describes the incidence of Multidrug resistance (MDR) CoNS from three hospitals in the uMgungundlovu District in the KwaZulu-Natal Province in South Africa
Eighty-nine (89) out of the 130 presumptive isolates were confirmed as CoNS by the automated VITEK 2 system and used for further analysis

Summary

Introduction

Coagulase-negative staphylococci (CoNS) are the most frequent colonizers of the skin and mucous membranes and the most frequently isolated organisms in microbiology laboratories [2]. The skin and mucous membranes of the host, which are home to an abundance of CoNS species, are significant sources of endogenous CoNS infections, facilitated by transmission through medical procedures [3]. CoNS are the most common pathogens implicated in nosocomial bloodstream infections, responsible for 30–40% of these infections [4]. A study found a CoNS prevalence of 6–68% in suspected human infections in Africa within the last decade [2]. Of the CoNS, Staphylococcus epidermidis is the most common cause of human infection, culpable for about 24–80% of these infections [3]

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