quality in diagnostic pathology comprises quality assurance ( qa ) and quality control ( qc ) .
while qa mainly involves external activities that check the final specific results that may impact on patient outcomes , qc involves internal activities that insure diagnostic accuracy .
qa is associated with reduced turnaround time for diagnosis of infection , which in turn influences cost / length of stay of patient in the hospital as well as the clinician and patient satisfaction .
qa in clinical microbiology is expected to be comprehensive , covering all aspects of the preanalytical , analytical , and postanalytical phases .
for instance , any clerical errors at pre- or postanalytical phase can ultimately lead to the generation of a faulty report .
however , external qa may not decipher between personnel or standard operational procedure ( sop ) of a registered facility , but internal qc does .
qc is the bedrock of qa , because much of the timely reporting of accurate test results depends on the practice of rigorous qc .
the two major factors that influence qa and qc in the analytical phase of diagnostic microbiology are ( 1 ) personnel and ( 2 ) the process , materials , and methods used in the laboratory . the first refers to the competency or dexterity of individual scientific / technical staff and the second refers to the sops .
the author has been privileged to work in three microbiology laboratories from across three different countries and continents .
based on the hands - on experience and interaction with colleagues , it can be said with certainty that most laboratory facilities have sops for their tests .
indeed , a survey had reported that many laboratories neither have a qc program , nor an sop for the tests they performed .
this experiential technical note presents case reports on four different scenarios requiring internal qc . the objective is to provide evidence base to highlight the value of internal qc program in evaluating the effectiveness and efficiency of the processes , materials , and methods used in the laboratory and the individual scientific / technical staff .
the issue of microbiology turnaround time as part of quality with obvious benefits for clinicians and patients is not new .
this is hallmarked by the development of technologies such as ( i ) assorted chromogenic media to enable identification of candidiasis , escherichia coli , group - b streptococcus , mrsa , and vre , possibly within 24 hours ; ( ii ) automated flow cytometry system for urine culture ; and ( iii ) polymerase chain reaction methods for many organisms , including chlamydia trachomatis , mycobacterium tuberculosis , and neisseria gonorrhoea , among others .
as always , there are still some cases that could not be decided and reported within the turnaround time
. there are gram - negative rods ( gnrs ) or gram - positive cocci ( gpc ) cultures for identification that can be undecided within the turnaround time .
worthy of mention in this note on quality is a cursory observation of , albeit nondifficult , three cases that could not be reported within the turnaround time .
they include salmonella specie mimicking escherichia coli on chromogenic agar , false - positive methicillin - resistant staphylococcus aureus based on color development in the chromogenic agar plate , and gnr from ( aerobic and anaerobic ) blood culture bottles with inconsistent chromogenic plate presentation .
all three cases share one thing ( false - positive chromogenic culture growth ) in common , which was identified by the sop that requires all chromogenic cultures should be accompanied by other culture media , or a positive chromogenic culture be subcultured for verification .
six microbiology laboratory units of a large pathology facility performed internal laboratory qc activities between february 2009 and july 2010 .
a total of ten qc cases were performed , of which four has been discretionally selected for this technical note [ table 1a and b ] .
( a ) results of organism identification 33% inaccuracy ( b ) antimicrobial susceptibility result indicating disparities in advice on antibiotic qc 1/2009 was taken from the sputum culture of a 10-year - old girl with cystic fibrosis .
although with other characteristics , it appeared to be a mucoid pseudomonas aeruginosa , a 20ne was set up .
although it appears that the shewanella and burkholderia results produced by other laboratories came from wrong api results , it was pleasing to note complete agreement on antibiotic susceptibility testing on this isolate . based on the date of dispatch being monday , february 16 and the receipt of reports being between february 19 and march 2 ,
it was also noted that the turnaround times for this particular qc ranged from 2 to 13 days .
qc 2/2009 was atypical streptococcus pneumoniae taken from the eye swab of a 34-year - old woman with conjunctivitis .
this isolate presented with poor growth and was not producing the completely typical colonial morphology .
, all other laboratories correctly identified the isolate as having reduced susceptibility to penicillin and ampicillin .
also , the reports varied considerably on the antibiotics tested and/or reported . for instance , lab 1 tested cefotaxime as resistant but did not report it ; whereas labs 4 and 6 tested and reported it as susceptible .
qc 1/2010 was isolated at a count of > 10 /liter from mid - stream urine culture of an 81-year - old man with renal failure .
all laboratories correctly identified this isolate as enterococci as well as tested and unanimously reported vancomycin as resistant .
however , the results varied a bit in  specie level identification and in nitrofurantoin susceptibility [ table 1 ] .
if antibiotic treatment is required , nitrofurantoin is very much the first option with which to treat vre in a patient with a urinary tract infection .
therefore , the variation in results indicated obvious difference in effectiveness or quality regarding choice of nitrofurantoin with the strain of vancomycin - resistant enterococcus faecium .
internal lab qc reports from six microbiology units of a laboratory service showing differences in outcomes that indicate concern for quality control .
qc 2/2010 was a streptococcus pneumoniae isolate grown from the ear swab received from a 66-year - old man .
pneumoniae colony from a primary plate , but later realized there was s. aureus underneath the colony .
one of the reasons for performing antimicrobial susceptibility testing for patient care is to detect new antimicrobial resistance strains or trends .
bench has involved performing a direct susceptibility ( ds ) testing for any pure growth of gnr . at some point in 2010 , the method of calibrated dichotomous susceptibility ( cds ) was to be implemented . to determine quality
, the qa officer authorized that the pathology service must perform a comparative evaluation of cds results against the established ds protocol .
the report of this evaluation has been used to show proof of correlation and qc during the re - accreditation visit of nata in 2011 .
this report being included here is to highlight the need for such evaluation , with or without any pending accreditation agenda .
overall annular radius from the ds is statistically significantly greater than in cds ( p < 0.01 ) ; although with the exception of ciprofloxacin and norfloxacin , the differences observed in other antibiotics did not achieve statistical significance [ table 2 ] .
calibrated dichotomous susceptibility vs. direct susceptibility comparative testing on urinary e. coli measures of annular radius of various antibiotic discs moxifloxacin ( mxf ) is a third - generation synthetic fluoroquinolone chemotherapeutic agent developed by bayer ag ( initially called bay 12 - 8039 ) .
it is also available in parenteral form for intravenous infusion as well as in an ophthalmic solution ( eye drops ) under the brand name vigamox for the treatment of conjunctivitis .
of particular interest here is that it was marketed as the heir apparent to ciprofloxacin ( cip ) .
specifically , mxf is attributed to have a broad - spectrum antibiotic activity against gnr and gpc . due to the notion that it is bayer 's heir apparent to cip
, there is the attendant opinion that mxf is superior to cip both in susceptibility and in toxicity . in our laboratory at swps ,
mxf susceptibility neither has been tested nor has advice regarding it been sought by clinicians . on advice to start stocking mxf discs , permission to run a brief evaluation
, literature indicated that mxf could be more effective than cip against gram - positive bacteria , but less effective against gram - negative bacteria ; although meca - positive staphylococcus species could be equally resistant to cip and mxf . on this basis ,
qc cultures of e. coli , p. aeruginosa , s. aureus , and s. epidermidis were used for the evaluation .
wild strains ( patients isolates ) of klebsiella oxythoca , mr_cons , mrsa , and mrsaca were used as well [ figure 1 ] .
susceptibility cultures showing ciprofloxacin vs. moxifloxacin comparison on different staph species on average , the comparative annular radius of cip and mxf observed were mrsa  wild ( mxf 2.0 mm , cip 0.0 mm ) ; and mrsaca  wild ( mxf 12.3 mm , cip 9.9 mm ) .
others were qc s. aureus ( mxf 13.0 mm , cip 11.0 mm ) , qc s. epidermidis ( mxf 6.0 mm , cip < 6.0 mm ) , qc p. aeruginosa ( mxf 9.3 mm , cip 13.1 mm ) , qc e. coli ( mxf 11.7 mm , cip 13.5 mm ) , and wild k. oxythoca ( mxf 8.4 mm , cip 10.3 mm ) .
as always , there are still some cases that could not be decided and reported within the turnaround time
. there are gram - negative rods ( gnrs ) or gram - positive cocci ( gpc ) cultures for identification that can be undecided within the turnaround time .
worthy of mention in this note on quality is a cursory observation of , albeit nondifficult , three cases that could not be reported within the turnaround time .
they include salmonella specie mimicking escherichia coli on chromogenic agar , false - positive methicillin - resistant staphylococcus aureus based on color development in the chromogenic agar plate , and gnr from ( aerobic and anaerobic ) blood culture bottles with inconsistent chromogenic plate presentation .
all three cases share one thing ( false - positive chromogenic culture growth ) in common , which was identified by the sop that requires all chromogenic cultures should be accompanied by other culture media , or a positive chromogenic culture be subcultured for verification .
six microbiology laboratory units of a large pathology facility performed internal laboratory qc activities between february 2009 and july 2010 . a senior microbiology scientist in - charge coordinated the program in an 
a total of ten qc cases were performed , of which four has been discretionally selected for this technical note [ table 1a and b ] .
( a ) results of organism identification 33% inaccuracy ( b ) antimicrobial susceptibility result indicating disparities in advice on antibiotic qc 1/2009 was taken from the sputum culture of a 10-year - old girl with cystic fibrosis .
although with other characteristics , it appeared to be a mucoid pseudomonas aeruginosa , a 20ne was set up .
although it appears that the shewanella and burkholderia results produced by other laboratories came from wrong api results , it was pleasing to note complete agreement on antibiotic susceptibility testing on this isolate .
based on the date of dispatch being monday , february 16 and the receipt of reports being between february 19 and march 2 , it was also noted that the turnaround times for this particular qc ranged from 2 to 13 days .
qc 2/2009 was atypical streptococcus pneumoniae taken from the eye swab of a 34-year - old woman with conjunctivitis .
this isolate presented with poor growth and was not producing the completely typical colonial morphology .
, all other laboratories correctly identified the isolate as having reduced susceptibility to penicillin and ampicillin .
also , the reports varied considerably on the antibiotics tested and/or reported . for instance , lab 1 tested cefotaxime as resistant but did not report it ; whereas labs 4 and 6 tested and reported it as susceptible .
qc 1/2010 was isolated at a count of > 10 /liter from mid - stream urine culture of an 81-year - old man with renal failure .
all laboratories correctly identified this isolate as enterococci as well as tested and unanimously reported vancomycin as resistant .
if antibiotic treatment is required , nitrofurantoin is very much the first option with which to treat vre in a patient with a urinary tract infection .
therefore , the variation in results indicated obvious difference in effectiveness or quality regarding choice of nitrofurantoin with the strain of vancomycin - resistant enterococcus faecium .
internal lab qc reports from six microbiology units of a laboratory service showing differences in outcomes that indicate concern for quality control .
qc 2/2010 was a streptococcus pneumoniae isolate grown from the ear swab received from a 66-year - old man .
pneumoniae were accurate . however , there was considerable variation in the identification report [ table 1 ] .
pneumoniae colony from a primary plate , but later realized there was s. aureus underneath the colony .
qc 1/2009 was taken from the sputum culture of a 10-year - old girl with cystic fibrosis .
although with other characteristics , it appeared to be a mucoid pseudomonas aeruginosa , a 20ne was set up .
although it appears that the shewanella and burkholderia results produced by other laboratories came from wrong api results , it was pleasing to note complete agreement on antibiotic susceptibility testing on this isolate .
based on the date of dispatch being monday , february 16 and the receipt of reports being between february 19 and march 2 , it was also noted that the turnaround times for this particular qc ranged from 2 to 13 days .
qc 2/2009 was atypical streptococcus pneumoniae taken from the eye swab of a 34-year - old woman with conjunctivitis .
this isolate presented with poor growth and was not producing the completely typical colonial morphology .
, all other laboratories correctly identified the isolate as having reduced susceptibility to penicillin and ampicillin .
also , the reports varied considerably on the antibiotics tested and/or reported . for instance , lab 1 tested cefotaxime as resistant but did not report it ; whereas labs 4 and 6 tested and reported it as susceptible .
qc 1/2010 was isolated at a count of > 10 /liter from mid - stream urine culture of an 81-year - old man with renal failure .
all laboratories correctly identified this isolate as enterococci as well as tested and unanimously reported vancomycin as resistant .
however , the results varied a bit in  specie level identification and in nitrofurantoin susceptibility [ table 1 ] .
if antibiotic treatment is required , nitrofurantoin is very much the first option with which to treat vre in a patient with a urinary tract infection .
therefore , the variation in results indicated obvious difference in effectiveness or quality regarding choice of nitrofurantoin with the strain of vancomycin - resistant enterococcus faecium .
internal lab qc reports from six microbiology units of a laboratory service showing differences in outcomes that indicate concern for quality control .
qc 2/2010 was a streptococcus pneumoniae isolate grown from the ear swab received from a 66-year - old man .
pneumoniae were accurate . however , there was considerable variation in the identification report [ table 1 ] .
pneumoniae colony from a primary plate , but later realized there was s. aureus underneath the colony .
one of the reasons for performing antimicrobial susceptibility testing for patient care is to detect new antimicrobial resistance strains or trends .
 bench has involved performing a direct susceptibility ( ds ) testing for any pure growth of gnr . at some point in 2010 , the method of calibrated dichotomous susceptibility ( cds ) was to be implemented . to determine quality
, the qa officer authorized that the pathology service must perform a comparative evaluation of cds results against the established ds protocol .
the report of this evaluation has been used to show proof of correlation and qc during the re - accreditation visit of nata in 2011 .
this report being included here is to highlight the need for such evaluation , with or without any pending accreditation agenda .
overall annular radius from the ds is statistically significantly greater than in cds ( p < 0.01 ) ; although with the exception of ciprofloxacin and norfloxacin , the differences observed in other antibiotics did not achieve statistical significance [ table 2 ] .
calibrated dichotomous susceptibility vs. direct susceptibility comparative testing on urinary e. coli measures of annular radius of various antibiotic discs
moxifloxacin ( mxf ) is a third - generation synthetic fluoroquinolone chemotherapeutic agent developed by bayer ag ( initially called bay 12 - 8039 ) .
it is also available in parenteral form for intravenous infusion as well as in an ophthalmic solution ( eye drops ) under the brand name vigamox for the treatment of conjunctivitis .
of particular interest here is that it was marketed as the heir apparent to ciprofloxacin ( cip ) .
specifically , mxf is attributed to have a broad - spectrum antibiotic activity against gnr and gpc . due to the notion that it is bayer 's heir apparent to cip
, there is the attendant opinion that mxf is superior to cip both in susceptibility and in toxicity . in our laboratory at swps , mxf susceptibility neither has been tested nor has advice regarding it been sought by clinicians . on advice to start stocking mxf discs , permission to run a brief evaluation
, literature indicated that mxf could be more effective than cip against gram - positive bacteria , but less effective against gram - negative bacteria ; although meca - positive staphylococcus species could be equally resistant to cip and mxf . on this basis
, qc cultures of e. coli , p. aeruginosa , s. aureus , and s. epidermidis were used for the evaluation .
wild strains ( patients isolates ) of klebsiella oxythoca , mr_cons , mrsa , and mrsaca were used as well [ figure 1 ] .
susceptibility cultures showing ciprofloxacin vs. moxifloxacin comparison on different staph species on average , the comparative annular radius of cip and mxf observed were mrsa  wild ( mxf 2.0 mm , cip 0.0 mm ) ; and mrsaca  wild ( mxf 12.3 mm , cip 9.9 mm ) .
others were qc s. aureus ( mxf 13.0 mm , cip 11.0 mm ) , qc s. epidermidis ( mxf 6.0 mm , cip < 6.0 mm ) , qc p. aeruginosa ( mxf 9.3 mm , cip 13.1 mm ) , qc e. coli ( mxf 11.7 mm , cip 13.5 mm ) , and wild k. oxythoca ( mxf 8.4 mm , cip 10.3 mm ) .
some pathology management may argue that participation in external qa program ( qap ) is sufficient to measure the quality of performance of the laboratory 's facility , especially considering costs ; but it has been opposed as untrue .
for instance , one of the counter - arguments that quickly comes to mind is that qap is a form of proficiency survey that  merely provides a snapshot in time and should not be used as a substitute for a daily qc  with an internal laboratory qc program . in the context of effectiveness and efficiency , it is common knowledge that accurate clinical microbiology report that reaches the gp late may be effective but not efficient .
it was pleasing to note accuracy on antibiotic susceptibility testing , but the differences in turnaround times ranged from 2 to 13 days .
it was determined that some labs do put qap cases on the back burner to attend to urgent patients cases .
thus , it must be acknowledged that external qap report quite often shows a turnaround time that is not representative of standard sop ; and especially , the administrators of the external qap are not evaluating turnaround time .
this goes on to reaffirm that external qap should not be used as a substitute for a daily qc whereby a laboratory can perform a self - evaluation of its effectiveness regarding turnaround times . further , it is pertinent to note that excessive consciousness of turnaround time without qc could be counterproductive . in this report , three albeit nondifficult cases that could not be reported within the turnaround time are mentioned .
all three cases presented with false - positive chromogenic reactions based on which inaccurate reports could have been made within the turnaround time if there were no qc measures in the sops . besides cases requiring microscopic examination , these cases of cultures had  preliminary reports  such as ( 1 ) gram - negative rods ( gnrs ) or gram - positive cocci ( gpc ) isolated  identification and susceptibility to follow .
cases 2 - 4 of the internal lab qc provide opportunities that require improvement in the analytical sop . of particular relevance to customer / patient outcome , for instance , conjunctivitis is often treated topically and the antibiotic used most commonly is chloramphenicol eye drops .
hence a viable alternative recommendation is good practice . considering the internal lab qc for  case 3
, there was a real difference in the sops , whereby some laboratory units read < 6.0 mm annular radius for nitrofurantoin as resistant , whereas some others use 4.0 mm as cut - off .
bearing in mind that whether the specimen is urine , in which there are large amounts of the antibiotic , or swabs ( respiratory , skin , vaginal , etc .
, ) in which certain normal flora could be considered as significant pathogen ; there needs to be consistency in reports from different laboratory units going to a gp within a community .
thus , there is a need for internal lab or interlab qc program to monitor accuracy or proficiency of the sops . from the observation of statistically significant difference in annular radius between ds and cds ( p < 0.01 ) ,
the qc evaluation has at least informed the laboratory that there could be discrepancy in susceptibility test results depending on whether cds or ds method is used .
for instance , a critical evaluation of the results presented show that where 6.00 mm is the cut - off , the lower limits of trimethoprim ( tmp ) is susceptible by cds ( 6.22 mm ) , but resistant or intermediate by ds ( 5.47 mm ) .
similarly , the lower limits of gentamicin ( gm ) is susceptible by cds ( 6.86 mm ) , but resistant or intermediate by ds ( 5.95 mm ) [ table 2 ] . in the comparison of cip vs. mxf
, it is observed that multiresistant methicillin staph aureus ( mrsa ) were resistant to both cip and mxf , while nonmultiresistant methicillin staph aureus ( mrsaca ) and the tested gnrs were susceptible .
further difference was observed in the susceptibility of staphylococcus epidermidis , which was resistant to cip but susceptible to mxf [ figure 1 ] .
the observations are quite in agreement with those of duggirala et al . ; that mxf could be more effective against gram - positive bacteria and less effective against gram - negative bacteria relative to cip .
this experiential note emphasizes the need for laboratory 's self - evaluation to checkmate relative complacency and to ensure evidence - based confidence in everyday quality . it is a reminder to those microbiology laboratories that have neither internal qc programs , nor sop for the tests they performed to rethink quality in their diagnostic practice .
 background : quality control ( qc ) in diagnostic microbiology is a matter of effective , efficient , accurate reporting in the expected turnaround time . 
 major stages of the analytical  standard operational procedures  where qc could be easily affected include organism identification and antibacterial susceptibility testing.aim:the objective of this experiential technical note is to provide an evidence base to highlight the value of internal qc program in evaluating the effectiveness and efficiency of a laboratory 's standard operational procedures ; and the competences of individual scientific / technical staff.materials and methods : this report is based on four different scenarios requiring internal qc , including cases that are not reported within the turnaround time of standard operational procedures . 
 small - scale evaluations of ( i ) internal qc program , ( ii ) ciprofloxacin vs. moxifloxacin susceptibilities , and ( iii ) calibrated dichotomous susceptibility vs. directed susceptibility testing were performed.results:the internal qc program identified sources of discrepancies in laboratory results . 
 evidence base for decision on new methodology and antibiotic testing were developed . 
 for instance , it is observed that calibrated dichotomous susceptibility gives greater annular radius than directed susceptibility ( p < 0.01).conclusions : internal qc program continues to be valuable means of identifying discrepancies , and vetting new ideas . 
 this report presents evidence base to reaffirm that the need for internal qc is ever present . 
Introduction
Case Reports and QC Scenarios
Some cases not reported within turnaround time
Internal lab QC
Case 1
Case 2
Case 3
Case 4
CDS vs. CD comparison
Ciprofloxacin vs. Moxifloxacin comparison
Discussion
Conclusion