On-line version ISSN 2078-5135
SAMJ, S. Afr. med. j. vol.101 n.2 Cape Town Feb. 2011
Bacteria isolated from bloodstream infections at a tertiary care hospital in Dar es Salaam, Tanzania - antimicrobial resistance of isolates
To the Editor: Retrospective antimicrobial susceptibility profiles from bloodstream infection isolates in Tanzania indicated increasing antimicrobial resistance to the first-line and inexpensive antimicrobial agents.1 Prospective methicillin-resistant Staphylococcus aureus (MRSA) or extended-spectrum beta-lactamase (ESBL) screening should be accompanied by watching multidrug-resistant (MDR) isolates and their susceptibility to first-line antibiotics. MDR isolates in local circulation might still turn out to be susceptible to such drugs, as was found at Sant Parmanand Hospital, a 140-bed private, tertiary care, multidisciplinary hospital in Delhi. From January to November 2010, 5 MDR bacteria were isolated from patients with serious infections.
Isolates were identified by their phenotypic and biochemical characterisation. The antibiotic susceptibility was tested by disk diffusion methods following the Clinical and Laboratory Standards Institute (CLSI) criteria. MDR Gram-negative strains were defined to be resistant to meropenem, piperacillin-tazobactam, cefepime, amoxicillin-clavulanic acid and amikacin. The 5 MDR Klebsiella pneumoniae from 1 133 isolates were isolated from urine in 3 patients and from purulent material in 2. Isolates identified included K. pneumoniae (468), Escherichia coli (413), Salmonella typhi/paratyphi A, B group (32), S. aureus (110), S. citreus (2), Pseudomonas aeruginosa (106) and Proteus spp. (2). All 3 MDR isolates from urine were susceptible to tigecycline, 2 to ciprofloxacin and 1 each to ofloxacin or rifampicin. Both MDR isolates from purulent materials were susceptible to tigecycline, ofloxacin and chloramphenicol, while 1 each was susceptible to aztroenam or rifampicin.
An annual rather than a 5-year update1 on local antibiotic susceptibility profiles would be useful for clinicians, who would be able to refer to the previous local antimicrobial susceptibility pattern during pilot antibiotic prescription for their patients. This would be useful before results of in vitro susceptibility of isolates are available. For example, the first-line, inexpensive antimicrobials1 that were developed in the 1940s and 1950s would not be the initial choice among clinicians managing patients with severe MDR. However, they might be the only option available in some cases, even if the in vitro susceptibility profiles are dismal.1
The technical assistance of Ms Umanga Chattri is acknowledged.
Subhash C Arya
Sant Parmanand Hospital
1. Moyo S, Aboud S, Kasubi M, Maselle SY. Bacteria isolated from bloodstream infections at a tertiary care hospital in Dar es Salaam, Tanzania - antimicrobial resistance of isolates. S Afr Med J 2010;100:835-838. [ Links ]
Dr S Moyo replies: Our 5-year retrospective analysis was aimed at establishing the aetiological agents and their antimicrobial resistance patterns. We established that MRSA and ESBL were also of public health importance in our settings. Since it was a retrospective analysis we could not investigate for MDR. We have recently shown a high prevalence of ESBL-producing E. coli and Klebsiella spp. strains from urine samples, and most of the ESBL-producing isolates were MDR, limiting available therapeutic choices.1 We are currently conducting another prospective study to monitor the trends of MRSA and to determine the presence of MDR. These results, together with the previous ones, will guide antimicrobial prescribing practice by our clinicians. MDR bacteria may be susceptible to the first-line antibiotics, but this was not apparent in our study. In vitro susceptibility results may not necessarily reflect what would happen in vivo. Our view is that when managing patients with severe infections due to MDR organisms, the first-line antibiotics should not be used in order to reduce morbidity and mortality that could be associated with life-threatening infections. In tertiary hospitals like ours or the authors', first-line antibiotics might not be the only option available for management of such cases, as suggested.
1. Moyo SJ, Aboud S, Kasubi M, Lyamuya EF, Maselle SY. Antimicrobial resistance among producers and non-producers of extended spectrum beta-lactamases in urinary isolates at a tertiary hospital in Tanzania. BMC Research Notes 2010;3:348 (24 December 2010). [ Links ]