Development of antimicrobial resistance has been assigned to excess and misuse
of antimicrobial agents. Staphylococci are part of the normal flora but are also
potential pathogens that have become essentially resistant to many known
antibiotics. Resistances in coagulase negative staphylococci (CoNS) are
suggested to evolve due to positive selective pressure following antibiotic
treatment. This study investigated the presence of the nine most commonly used
antimicrobial agents in human urine from outpatients in two hospitals in Ghana in
relation to CoNS resistance. Urine and CoNS were sampled (n5246 and n596
respectively) from patients in two hospitals in Ghana. CoNS were identified using
Gram staining, coagulase test, and MALDI-TOF/MS, and the antimicrobial
susceptibility to 12 commonly used antimicrobials was determined by disk diffusion.
Moreover an analytical method was developed for the determination of the nine
most commonly used antimicrobial agents in Ghana by using solid-phase
extraction in combination with HPLC-MS/MS using electron spray ionization. The
highest frequency of resistance to CoNS was observed for penicillin V (98%),
trimethoprim (67%), and tetracycline (63%). S. haemolyticus was the most common
isolate (75%), followed by S. epidermidis (13%) and S. hominis (6%). S. haemolyticus was also the species displaying the highest resistance prevalence
(82%). 69% of the isolated CoNS were multiple drug resistant (§4 antibiotics) and
45% of the CoNS were methicillin resistant. Antimicrobial agents were detected in
64% of the analysed urine samples (n5121) where the most frequently detected
antimicrobials were ciprofloxacin (30%), trimethoprim (27%), and metronidazole
(17%). The major findings of this study was that the prevalence of detected
antimicrobials in urine was more frequent than the use reported by the patients and the prevalence of resistant S. haemolyticus was more frequent than other resistant CoNS species when antimicrobial agents were detected in the urine.